[Dentinopulpar organ: biological basis of clinical response to Ca(OH)2 application].

PubMed

Gani, O; Crosa, M E

1989-01-01

We have studied the changes presented by mediate and immediate roentgenographic images of indirect pulp capping and pulpotomies. In the cases of indirect pulp capping it was observed an increase of radiolucidity in the places occupied by Ca(OH)2, and sclerotic dentin was present. In pulpotomies, it was found the dentin bridge, which thickness increases with time. The radiolucidity of pulp chamber occupied by Ca(OH)2 was greater in the long time treatment. The radiopacity of non-vital dentin of walls and floor chamber was increased too. It has suggested that Ca++ ion would have migrated from its place and probably would take part in the synthesis of sclerotic dentin, independently of the vitality of the tissue.

Controlled release of lovastatin from poly(lactic-co-glycolic acid) nanoparticles for direct pulp capping in rat teeth.

PubMed

Lin, Hung-Pin; Tu, Han-Ping; Hsieh, Yu-Ping; Lee, Bor-Shiunn

2017-01-01

Statin at appropriate concentrations has been shown to induce odontoblastic differentiation, dentinogenesis, and angiogenesis. However, using a carrier to control statin release might reduce toxicity and enhance its therapeutic effects. The aim of this study was to prepare poly(d,l-lactide- co -glycolide acid) (PLGA) nanoparticles that contain lovastatin for application in direct pulp capping. The PLGA-lovastatin particle size was determined using dynamic light scattering measurements and transmission electron microscopy. In addition, the release of lovastatin was quantified using a UV-Vis spectrophotometer. The cytotoxicity and alkaline phosphatase (ALP) activity of PLGA-lovastatin nanoparticles on human dental pulp cells were investigated. Moreover, a real-time polymerase chain reaction (PCR) assay, Western blot analysis, and an enzyme-linked immunosorbent assay (ELISA) were used to examine the osteogenesis gene and protein expression of dentin sialophosphoprotein (DSPP), dentin matrix acidic phosphoprotein 1 (DMP1), and osteocalcin (OCN). Finally, PLGA-lovastatin nanoparticles and mineral trioxide aggregate (MTA) were compared as direct pulp capping materials in Wistar rat teeth. The results showed that the median diameter of PLGA-lovastatin nanoparticles was 174.8 nm and the cumulative lovastatin release was 92% at the 44th day. PLGA-lovastatin nanoparticles demonstrated considerably a lower cytotoxicity than free lovastatin at 5, 9, and 13 days of culture. For ALP activity, the ALP amount of PLGA-lovastatin (100 μg/mL) was significantly higher than that of the other groups for 9 and 13 days of culture. The real-time PCR assay, Western blot analysis, and ELISA assay showed that PLGA-lovastatin (100 μg/mL) induced the highest mRNA and protein expression of DSPP, DMP1, and OCN in pulp cells. Histological evaluation of the animal studies revealed that MTA was superior to the PLGA-lovastatin in stimulating the formation of tubular dentin in an observation period of 2 weeks. However, in an observation period of 4 weeks, it was evident that the PLGA-lovastatin and MTA were competitive in the formation of tubular reparative dentin and a complete dentinal bridge.

A Histopathological Comparison of Pulpal Response to Chitra-CPC and Formocresol used as Pulpotomy Agents in Primary Teeth: A Clinical Trial

PubMed Central

Thomas, Bijimol

2012-01-01

ABSTRACT Preventive measures have helped to minimize the occurrence of dental caries. However, premature loss of primary teeth on account of dental caries still remains a common problem among children. The pulpotomy technique has been the choice for treating vital primary and young permanent teeth with carious, mechanical and traumatic pulp exposures. The ideal pulpotomy medicament should be bioinductive or at least biocompatible, bactericidal and harmless to the pulp and surrounding structures. It should also promote healing of the radicular pulp and prevent bacterial microleakage with the least interference in the physiological process of root resorption. Since the best criteria for judging the effectiveness of a medicament when used for vital pulp therapy is the response that it produces in the pulp. The purpose of the present study was to evaluate and compare the response of human pulp tissue to recently developed Indian material, Sree Chitra-Calcium Phosphate Cement (Chitra-CPC) and formocresol, used as pulpotomy agent in deciduous teeth. Chitra-CPC has been compared with formocresol, taking into account that formocresol is still considered the gold standard in primary tooth pulpotomy. The study was conducted among 10 children in the age group of 8 to 12 years focusing on 20 noncarious primary canines indicated for serial extraction. Each patient received two different pulpotomy procedures—one in each of the primary canines using formocresol and the other with Chitra-CPC as pulpotomy agents. After 70 days, the teeth were extracted and subjected to histological examination. The results did not reveal statistically significant difference between the two groups. But Chitra-CPC gave more favorable results, in respect of pulpal inflammation, dentin bridge formation, quality of dentin bridge and connective tissue in dentin bridge. How to cite this article: Ratnakumari N, Thomas B. A Histopathological Comparison of Pulpal Response to Chitra- CPC and Formocresol used as Pulpotomy Agents in Primary Teeth: A Clinical Trial. Int J Clin Pediatr Dent 2012;5(1):6-13. PMID:25206127

Bioactive glass for dentin remineralization: A systematic review.

PubMed

Fernando, Delihta; Attik, Nina; Pradelle-Plasse, Nelly; Jackson, Phil; Grosgogeat, Brigitte; Colon, Pierre

2017-07-01

Strategies to achieve dentin remineralization is at present an important target of restorative dentistry. Remineralization of dentin by a bioactive material is complete only when the tissue regains its functionality. This is achieved when there is adequate apatite formation which most importantly translates into improved mechanical properties of dentin as a result of intrafibrillar mineralization. Bioactive glass (BAG) is a well-known implant material for bone regeneration and is proven to have excellent ability of apatite formation. Hence, recent studies have proposed BAGs as one of the most desired materials for remineralization of dentin. Therefore the aim of this systematic review was to scope the evidence of bioactive glass to remineralize dentin. The following research question was formulated: "Is there strong evidence for bioactive glass to remineralize dentin?" Three databases (Web of science, PubMed and Science direct) were scanned independently following PRISMA guidelines. Inclusion and exclusion criteria were set to identify relevant articles based on title and abstract screening. Finally, potentially relevant articles were downloaded and the full text was scrutinized to select the articles included in this review. The first phase of search returned 303 articles. A total of 19 papers with full text were scrutinized for inclusion, of which 3 papers were chosen for the final synthesis. All three studies confirm that BAG treatment leads to enhanced apatite formation in dentin. Only 1 of the 3 studies has reported the mechanical properties of dentin after BAG treatment and it revealed that the Young's modulus and flexural bend strength of BAG treated dentin were much lower than natural dentin even though they had similar apatite content. This review highlights the importance of assessing the mechanical properties of dentin alongside to the newly formed apatite content in order to prove BAGs efficiency to remineralize this tissue. Though studies have confirmed that BAGs stimulate excellent apatite formation in dentin, it should be concluded that there isn't sufficient evidence for bioactive glass to effectively remineralize this tissue as the mechanical properties of the BAG treated dentin haven't been well explored. Copyright © 2017 Elsevier B.V. All rights reserved.

Relationship between water status in dentin and interfacial morphology in all-in-one adhesives.

PubMed

Yoshida, Eiji; Uno, Sigeru; Nodasaka, Yoshinobu; Kaga, Msayuki; Hirano, Susumu

2007-05-01

All-in-one adhesive systems have been recently developed to simplify bonding procedures. The adhesives containing acidic resin monomers generate a relatively thin bonding zone between dentin and composite. This zone may be left acidic and permeable when polymerization is poor. In this study, the effect of water contained in dentin on the quality of the bonding interface was morphologically investigated for all-in-one adhesives. Intact coronal dentin (hydrated dentin), desiccated coronal dentin (dehydrated dentin), caries-affected dentin (CAD) and resin composites were used for adherends to assess the effects of water contained in dentin on the ultra-structures of bonding interfaces created with two all-in-one adhesives and a resin composite. The bonding interfaces were observed under TEM without demineralization. Voids of various sizes were found at the bottom of the adhesive resin layers along the bonding interface of hydrated dentin, while dehydrated dentin, CAD and resin composites did not generate voids. The results showed that the voids were possibly formed by water that had penetrated from the underlying dentin. When the adherend contains little water, the formation of voids will not occur. It was verified that a phenomenon of void formation would not occur in a clinical situation in which caries-affected dentin is mainly subjected to adhesive practices.

Conservative approach of a symptomatic carious immature permanent tooth using a tricalcium silicate cement (Biodentine): a case report

PubMed Central

Grosgogeat, Brigitte; Seux, Dominique; Farge, Pierre

2013-01-01

The restorative management of deep carious lesions and the preservation of pulp vitality of immature teeth present real challenges for dental practitioners. New tricalcium silicate cements are of interest in the treatment of such cases. This case describes the immediate management and the follow-up of an extensive carious lesion on an immature second right mandibular premolar. Following anesthesia and rubber dam isolation, the carious lesion was removed and a partial pulpotomy was performed. After obtaining hemostasis, the exposed pulp was covered with a tricalcium silicate cement (Biodentine, Septodont) and a glass ionomer cement (Fuji IX extra, GC Corp.) restoration was placed over the tricalcium silicate cement. A review appointment was arranged after seven days, where the tooth was asymptomatic with the patient reporting no pain during the intervening period. At both 3 and 6 mon follow up, it was noted that the tooth was vital, with normal responses to thermal tests. Radiographic examination of the tooth indicated dentin-bridge formation in the pulp chamber and the continuous root formation. This case report demonstrates a fast tissue response both at the pulpal and root dentin level. The use of tricalcium silicate cement should be considered as a conservative intervention in the treatment of symptomatic immature teeth. PMID:24303363

Mineral Apposition Rates in Coronal Dentine of Mandibular First Molars in Soay Sheep: Results of a Fluorochrome Labeling Study.

PubMed

Kahle, Patricia; Witzel, Carsten; Kierdorf, Uwe; Frölich, Kai; Kierdorf, Horst

2018-05-01

We studied the spatio-temporal variation of mineral apposition rate (MAR) in postnatally formed coronal dentine of mandibular first molars from Soay sheep repeatedly injected with different fluorochromes. MAR declined along the cuspal to cervical crown axis, and from early to late formed dentine, that is, from the dentine at the enamel-dentine-junction (EDJ) to the dentine adjacent to the dentine-pulp-interface (DPI). Highest mean MARs (about 21 µm/day) were recorded in cuspal dentine formed in the period of 28-42 days after birth. Lowest values (<2 µm/day) were recorded in late-formed (secondary) dentine close to the DPI. The high MARs recorded in the dentine of the cuspal crown portions enable the formation of a large tooth crown within a relatively short period of less than one year. The established MARs in the dentine of the different crown portions of sheep molars will allow a precise determination of the timing of stress events affecting dentine formation. They are also helpful for devising sampling protocols in studies of trace element or stable isotope distributions in sheep dentine aimed at assessing temporal variation of incorporation into forming dentine. Such data are useful in a variety of contexts, including, for example, the exposure to pollutants and the reconstruction of husbandry practices or feeding regimes. Anat Rec, 301:902-912, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Effect of nano-hydroxyapatite on bone morphogenetic protein-2-induced hard tissue formation and dentin resorption on a dentin surface

NASA Astrophysics Data System (ADS)

Tamagawa, Hiroki; Tenkumo, Taichi; Sugaya, Tsutomu; Kawanami, Masamitsu

2012-12-01

AimThe purpose of this study was to evaluate the effects of the addition of nano-hydroxyapatite to a collagen membrane-carrier of recombinant human bone morphogenetic protein-2 (rhBMP-2) on hard tissue formation and dentin resorption on dentin surfaces in vivo. Materials and methodsNano-hydroxyapatite collagen composite (nHAC) membranes or collagen (C) membranes were each immersed in either 100 or 400 μg/ml rhBMP-2 and placed on dentin chips that were implanted into rat thigh muscle. The implants were analyzed at 2 or 4 weeks after surgery by histological observation and histomorphometric analysis. ResultsThe percentage of the hard tissue formed by each nHAC group was significantly higher than that formed by any of the C groups, except for that formed by the group loaded with 400 μg/ml rhBMP-2 at 4 weeks after implantation. No significant differences were observed in the percentage of dentin resorption between the nHAC groups and C groups at any stage or at any rhBMP-2 concentration. ConclusionThese findings showed that addition of nano-hydroxyapatite to a collagen membrane accelerated the formation of hard tissue induced by a low dose of rhBMP-2 on dentin surfaces at an early stage after implantation into rat thigh muscle, without increasing dentin resorption.

Effect of white mineral trioxide aggregate compared with biomimetic carbonated apatite on dentine bridge formation and inflammatory response in a dental pulp model.

PubMed

Danesh, F; Vahid, A; Jahanbani, J; Mashhadiabbas, F; Arman, E

2012-01-01

  To evaluate the effects of apatite precipitation on the biocompatibility and hard tissue induction properties of white mineral trioxide aggregate (WMTA) in a dental pulp model.   Pulp exposures were created on the axial walls of 32 sound canine teeth of eight dogs. Four additional sound teeth served as controls. The pulps were capped either with WMTA or apatite derivatives [biomimetic carbonated apatite (BCAp)] in the interaction of WMTA with a synthetic tissue fluid and restored with zinc oxide-eugenol cement. After 7 and 70 days, the animals were killed, and the histological specimens taken from the teeth were stained with haematoxylin and eosin for histomorphological evaluation. The Brown and Brenn technique was employed to stain bacteria. The data were subjected to nonparametric Kruskall-Wallis analysis and Mann-Whitney U_tests.   Biomimetic carbonated apatite did not induce hard tissue bridge formation. WMTA performed significantly better than BCAp in this respect at both periods (P < 0.05). BCAp was associated with a significantly greater inflammatory response as compared with WMTA after 7 days (P < 0.05). Both materials were associated with similar reactions after 70 days (P >0.05).   White mineral trioxide aggregate induced hard tissue formation via a mechanism other than that postulated via apatite formation. © 2011 International Endodontic Journal.

Evaluation of Dentin Defect Formation during Retreatment with Hand and Rotary Instruments: A Micro-CT Study.

PubMed

Yilmaz, Ayca; Helvacioglu-Yigit, Dilek; Gur, Cansu; Ersev, Handan; Kiziltas Sendur, Gullu; Avcu, Egemen; Baydemir, Canan; Abbott, Paul Vincent

2017-01-01

The purpose of this study was to compare the incidence and longitudinal propagation of dentin defects after gutta-percha removal with hand and rotary instruments using microcomputed tomography. Twenty mandibular incisors were prepared using the balanced-force technique and scanned in a 19.9  μ m resolution. Following filling with the lateral compaction technique, gutta-percha was removed with ProTaper Universal Retreatment (PTUR) or hand instruments. After rescanning, a total of 24,120 cross-sectional images were analyzed. The numbers, types, and longitudinal length changes of defects were recorded. Defects were observed in 36.90% of the cross sections. A total of 73 defects were comprised of 87.67% craze lines, 2.73% partial cracks, and 9.58% fractures. No significant difference in terms of new defect formation was detected between the retreatment groups. The apical and middle portions of the roots had more dentin defects than the coronal portions. Defects in three roots of the PTUR instrument group increased in length. Under the conditions of this in vitro study, gutta-percha removal seemed to not increase the incidence of dentin defect formation, but the longitudinal defect propagation finding suggests possible cumulative dentinal damage due to additional endodontic procedures. Hand and rotary instrumentation techniques caused similar dentin defect formation during root canal retreatment.

The dentin-enamel junction and the fracture of human teeth.

PubMed

Imbeni, V; Kruzic, J J; Marshall, G W; Marshall, S J; Ritchie, R O

2005-03-01

The dentin-enamel junction (DEJ), which is the interfacial region between the dentin and outer enamel coating in teeth, is known for its unique biomechanical properties that provide a crack-arrest barrier for flaws formed in the brittle enamel1. In this work, we re-examine how cracks propagate in the proximity of the DEJ, and specifically quantify, using interfacial fracture mechanics, the fracture toughness of the DEJ region. Careful observation of crack penetration through the interface and the new estimate of the DEJ toughness ( approximately 5 to 10 times higher than enamel but approximately 75% lower than dentin) shed new light on the mechanism of crack arrest. We conclude that the critical role of this region, in preventing cracks formed in enamel from traversing the interface and causing catastrophic tooth fractures, is not associated with the crack-arrest capabilities of the interface itself; rather, cracks tend to penetrate the (optical) DEJ and arrest when they enter the tougher mantle dentin adjacent to the interface due to the development of crack-tip shielding from uncracked-ligament bridging.

The dentin-enamel junction and the fracture of human teeth

NASA Astrophysics Data System (ADS)

Imbeni, V.; Kruzic, J. J.; Marshall, G. W.; Marshall, S. J.; Ritchie, R. O.

2005-03-01

The dentin-enamel junction (DEJ), which is the interfacial region between the dentin and outer enamel coating in teeth, is known for its unique biomechanical properties that provide a crack-arrest barrier for flaws formed in the brittle enamel1. In this work, we re-examine how cracks propagate in the proximity of the DEJ, and specifically quantify, using interfacial fracture mechanics, the fracture toughness of the DEJ region. Careful observation of crack penetration through the interface and the new estimate of the DEJ toughness (~5 to 10 times higher than enamel but ~75% lower than dentin) shed new light on the mechanism of crack arrest. We conclude that the critical role of this region, in preventing cracks formed in enamel from traversing the interface and causing catastrophic tooth fractures, is not associated with the crack-arrest capabilities of the interface itself; rather, cracks tend to penetrate the (optical) DEJ and arrest when they enter the tougher mantle dentin adjacent to the interface due to the development of crack-tip shielding from uncracked-ligament bridging.

THE IMPORTANCE OF MICROSTRUCTURAL VARIATIONS ON THE FRACTURE TOUGHNESS OF HUMAN DENTIN

PubMed Central

Ivancik, J.; Arola, D.

2012-01-01

The crack growth resistance of human dentin was characterized as a function of relative distance from the DEJ and the corresponding microstructure. Compact tension specimens were prepared from the coronal dentin of caries-free 3rd molars. The specimens were sectioned from either the outer, middle or inner dentin. Stable crack extension was achieved under Mode I quasi-static loading, with the crack oriented in-plane with the tubules, and the crack growth resistance was characterized in terms of the initiation (Ko), growth (Kg) and plateau (Kp) toughness. A hybrid approach was also used to quantify the contribution of dominant mechanisms to the overall toughness. Results showed that human dentin exhibits increasing crack growth resistance with crack extension in all regions, and that the fracture toughness of inner dentin (2.2±0.5 MPa•m0.5) was significantly lower than that of middle (2.7±0.2 MPa•m0.5) and outer regions (3.4±0.3 MPa•m0.5). Extrinsic toughening, composed mostly of crack bridging, was estimated to cause an average increase in the fracture energy of 26% in all three regions. Based on these findings, dental restorations extended into deep dentin are much more likely to cause tooth fracture due to the greater potential for introduction of flaws and decrease in fracture toughness with depth. PMID:23131531

Effect of gamma irradiation on the wear behavior of human tooth dentin.

PubMed

Qing, Ping; Huang, Shengbin; Gao, ShanShan; Qian, LinMao; Yu, HaiYang

2016-12-01

The objective of this study was to evaluate the effect of gamma irradiation on the wear behavior of human tooth dentin in terms of possible alterations in crystallinity, grain size, and composition. Human premolars (n = 19) were collected to obtain the perpendicular or parallel to the direction of the dentin tubule specimens. Each specimen was subjected to 60 Gy of gamma irradiation, in daily increments of 2 Gy. The nanoscratch tests were conducted. The scratch traces were observed via scanning electron microscope (SEM) and surface profilometer. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to investigate the alteration of crystallography and chemical composition of dentin after irradiation. The change of surface microhardness (SMH) was also evaluated. The nanoscratch results showed that the friction coefficient of dentin after irradiation became higher, and the depths and widths of scratch were greater than that of dentin before irradiation. Additionally, irradiation decreased the crystallinity of dentin and induced the formation of bigger crystals. The carbonate/mineral ratio was increased. Furthermore, a significant reduction in microhardness after irradiation was observed. The main damage mechanisms consisted of the formation of delamination and crack in both the specimens cut perpendicular and parallel to tubule dentin after irradiation. Irradiation affected directly the wear behavior of tooth dentin, accompanied by the alterations in crystallography, chemical composition, and surface microhardness of dentin. This would help extend understanding the influence of irradiation on dentin and provide suggestions for selecting more suitable materials for irradiated tooth.

Influence of irrigation regimens on the adherence of Enterococcus faecalis to root canal dentin.

PubMed

Kishen, Anil; Sum, Chee-Peng; Mathew, Shibi; Lim, Chwee-Teck

2008-07-01

Enterococcus faecalis is frequently associated with post-treatment endodontic infections. Because adherence of bacteria to a substrate is the earliest stage in biofilm formation, eliciting the factors that links adherence of this bacterium to dentin would help in understanding its association with treatment-failed root canals. This investigation aimed to study the effects of endodontic irrigants on the adherence of E. faecalis to dentin. The bacteria adherence assay was conducted by using fluorescence microscopy, and the adhesion force was measured by using atomic force microscopy. There were significant increases in adherence and adhesion force after irrigation of dentin with ethylenediaminetetraacetic acid (EDTA), whereas sodium hypochlorite (NaOCl) reduced it. With the use of chlorhexidine (CHX), the force of adhesion increased, but the adherence assay showed a reduction in the number of adhering bacteria. The irrigation regimen of EDTA, NaOCl, and CHX resulted in the least number of adhering E. faecalis cells. This study highlighted that chemicals that alter the physicochemical properties of dentin will influence the nature of adherence, adhesion force, and subsequent biofilm formation of E. faecalis to dentin.

Assessment of dentin remineralization with PS-OCT

NASA Astrophysics Data System (ADS)

Manesh, Saman K.; Darling, Cynthia L.; Fried, Daniel

2009-02-01

Previous studies have demonstrated that polarization sensitive optical coherence tomography (PS-OCT) can be used to image natural root caries lesions, measure non-destructively the severity of dentin demineralization and determine the efficacy of intervention with anti-caries agents including fluoride and lasers. The objective of this study was to determine if PS-OCT could be used to nondestructively measure the formation of a layer of remineralized dentin on the surface of dentin lesions after exposure to a remineralization solution. In this study images of artificial dentin lesions on extracted human teeth were acquired using PS-OCT after exposure to an artificial demineralizing solution at pH 4.9 for six days and after subsequent exposure to a remineralizing solution at pH 7.0 for 20 days. Polarized light microscopy and microradiography were used to examine histological thin sections from the samples for comparison. PS-OCT successfully measured the formation of a layer of increased mineral content near the lesion surface. PLM and TMR corroborated those results. This study demonstrates the potential use of PS-OCT for the nondestructive measurement of the remineralization of dentin surfaces.

Synthetic octacalcium phosphate-enhanced reparative dentine formation via induction of odontoblast differentiation.

PubMed

Wang, Xiaogu; Suzawa, Tetsuo; Miyauchi, Tomohiko; Zhao, Baohong; Yasuhara, Rika; Anada, Takahisa; Nakamura, Masanori; Suzuki, Osamu; Kamijo, Ryutaro

2015-11-01

Synthetic octacalcium phosphate (OCP) has been suggested to be a useful biomaterial for the regeneration of hard tissues, including bone. However, it remains unknown whether OCP induces dentine formation by dental pulp. We investigated biomineralization of dental pulp exposed to synthetic OCP in vitro and in vivo. When dental pulp was exposed directly to OCP, rapid formation of reparative dentine (RD) was induced and expression of dentine sialoprotein synthesis was observed in dental pulp adjacent to newly synthesized RD. OCP inhibited the proliferation of rat pulp cells and also promoted their odontoblastic differentiation in vitro, as alkaline phosphatase activity, mineralization of pulp cells and the expression level of dentine sialophosphoprotein were enhanced. Direct contact between OCP and pulp cells is required for OCP to exhibit its effects in vitro. The expression level of Runx2, a transcription factor whose downregulation is closely related to odontoblast differentiation, was downregulated in pulp cells cultured with OCP. Structural changes of OCP during culture were determined by Fourier transform infrared spectroscopy. OCP tended to be converted to carbonate hydroxyapatite after incubation with or without pulp cells, which may be analogous to biological apatite crystals. Taken together, our data suggest that synthetic OCP supports RD formation by dental pulp and downregulation of Runx2 may be involved in that stimulatory activity. Furthermore, OCP-apatite conversion is involved in this stimulatory capacity of OCP. Copyright © 2013 John Wiley & Sons, Ltd.

Dentin matrix protein 1 and phosphate homeostasis are critical for postnatal pulp, dentin and enamel formation

PubMed Central

Rangiani, Afsaneh; Cao, Zheng-Guo; Liu, Ying; Voisey Rodgers, Anika; Jiang, Yong; Qin, Chun-Lin; Feng, Jian-Quan

2012-01-01

Deletion or mutation of dentin matrix protein 1 (DMP1) leads to hypophosphatemic rickets and defects within the dentin. However, it is largely unknown if this pathological change is a direct role of DMP1 or an indirect role of phosphate (Pi) or both. It has also been previously shown that Klotho-deficient mice, which displayed a high Pi level due to a failure of Pi excretion, causes mild defects in the dentinal structure. This study was to address the distinct roles of DMP1 and Pi homeostasis in cell differentiation, apoptosis and mineralization of dentin and enamel. Our working hypothesis was that a stable Pi homeostasis is critical for postnatal tooth formation, and that DMP1 has an antiapoptotic role in both amelogenesis and dentinogenesis. To test this hypothesis, Dmp1-null (Dmp1−/−), Klotho-deficient (kl/kl), Dmp1/Klotho-double-deficient (Dmp1−/−/kl/kl) and wild-type (WT) mice were killed at the age of 6 weeks. Combinations of X-ray, microcomputed tomography (μCT), scanning electron microscopy (SEM), histology, apoptosis and immunohistochemical methods were used for characterization of dentin, enamel and pulp structures in these mutant mice. Our results showed that Dmp1−/− (a low Pi level) or kl/kl (a high Pi level) mice displayed mild dentin defects such as thin dentin and a reduction of dentin tubules. Neither deficient mouse line exhibited any apparent changes in enamel or pulp structure. However, the double-deficient mice (a high Pi level) displayed severe defects in dentin and enamel structures, including loss of dentinal tubules and enamel prisms, as well as unexpected ectopic ossification within the pulp root canal. TUNEL assay showed a sharp increase in apoptotic cells in ameloblasts and odontoblasts. Based on the above findings, we conclude that DMP1 has a protective role for odontoblasts and ameloblasts in a pro-apoptotic environment (a high Pi level). PMID:23258378

Dentin-cement Interfacial Interaction

PubMed Central

Atmeh, A.R.; Chong, E.Z.; Richard, G.; Festy, F.; Watson, T.F.

2012-01-01

The interfacial properties of a new calcium-silicate-based coronal restorative material (Biodentine™) and a glass-ionomer cement (GIC) with dentin have been studied by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), micro-Raman spectroscopy, and two-photon auto-fluorescence and second-harmonic-generation (SHG) imaging. Results indicate the formation of tag-like structures alongside an interfacial layer called the “mineral infiltration zone”, where the alkaline caustic effect of the calcium silicate cement’s hydration products degrades the collagenous component of the interfacial dentin. This degradation leads to the formation of a porous structure which facilitates the permeation of high concentrations of Ca2+, OH-, and CO32- ions, leading to increased mineralization in this region. Comparison of the dentin-restorative interfaces shows that there is a dentin-mineral infiltration with the Biodentine, whereas polyacrylic and tartaric acids and their salts characterize the penetration of the GIC. A new type of interfacial interaction, “the mineral infiltration zone”, is suggested for these calcium-silicate-based cements. PMID:22436906

Qualitative analysis of precipitate formation on the surface and in the tubules of dentin irrigated with sodium hypochlorite and a final rinse of chlorhexidine or QMiX.

PubMed

Kolosowski, Kamil P; Sodhi, Rana N S; Kishen, Anil; Basrani, Bettina R

2014-12-01

Interaction of sodium hypochlorite (NaOCl) mixed with chlorhexidine (CHX) produces a brown precipitate containing para-chloroaniline (PCA). When QMiX is mixed with NaOCl, no precipitate forms, but color change occurs. The aim of this study was to qualitatively assess the formation of precipitate and PCA on the surface and in the tubules of dentin irrigated with NaOCl, followed either by EDTA, NaOCl, and CHX or by saline and QMiX by using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Dentin blocks were obtained from human maxillary molars, embedded in resin, and cross-sectioned to expose dentin. Specimens in group 1 were immersed in 2.5% NaOCl, followed by 17% EDTA, 2.5% NaOCl, and 2% CHX. Specimens in group 2 were immersed in 2.5% NaOCl, followed by saline and QMiX. The dentin surfaces were subjected to TOF-SIMS spectra analysis. Longitudinal sections of dentin blocks were then exposed and subjected to TOF-SIMS analysis. All samples and analysis were performed in triplicate for confirmation. TOF-SIMS analysis of group 1 revealed an irregular precipitate, containing PCA and CHX breakdown products, on the dentin surfaces, occluding and extending into the tubules. In TOF-SIMS analysis of group 2, no precipitates, including PCA, were detected on the dentin surface or in the tubules. Within the limitations of this study, precipitate containing PCA was formed in the tubules of dentin irrigated with NaOCl followed by CHX. No precipitates or PCA were detected in the tubules of dentin irrigated with NaOCl followed by saline and QMiX. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

IDENTIFICATION OF A PROTEIN-CONTAINING ENAMEL MATRIX LAYER WHICH BRIDGES WITH THE DENTIN-ENAMEL JUNCTION OF ADULT HUMAN TEETH1

PubMed Central

Dusevich, Vladimir; Xu, Changqi; Wang, Yong; Walker, Mary P.; Gorski, Jeff P.

2012-01-01

Objective To investigate the ultrastructure and chemical composition of the dentin-enamel junction and adjacent enamel of minimally processed third molar tooth sections. Design Undecalcified human third molar erupted teeth were sectioned and etched with 4% EDTA or 37% phosphoric acid prior to visualization by scanning electron microscopy. Confocal Raman spectroscopy was carried out at 50 μm and more than 400 μm away from the dentin-enamel junction before and after mild etching. Results A novel organic protein-containing enamel matrix layer was identified for the first time using scanning electron microscopy of etched bucco-lingual sections of crowns. This layer resembles a three-dimensional fibrous meshwork that is visually distinct from enamel “tufts”. Previous studies have generally used harsher solvent conditions which likely removed this layer and precluded its prior characterization. The shape of the organic enamel layer generally reflected that of sheath regions of enamel rods and extended from the dentin-enamel junction about 100–400 μm into the cuspal enamel. This layer exhibited a Raman C—H stretching peak at ~2931 cm−1 characteristic of proteins and this signal correlated directly with the presence and location of the matrix layer as identified by scanning electron microscopy. Conclusions The enamel protein layer was most prominent close to the dentin-enamel junction and was largely absent in cuspal enamel >400 μm away from the dentin enamel junction. We hypothesize that this protein containing matrix layer could provide an important biomechanical linkage between the enamel and the dentin-enamel junction and by extension, with the dentin, of the adult tooth. PMID:22609172

TEM characterization of a silorane composite bonded to enamel/dentin.

PubMed

Mine, Atsushi; De Munck, Jan; Van Ende, Annelies; Cardoso, Marcio Vivan; Kuboki, Takuo; Yoshida, Yasuhiro; Van Meerbeek, Bart

2010-06-01

The low-shrinking composite composed of combined siloxane-oxirane technology (Filtek Silorane, 3M ESPE, Seefeld, Germany) required the development of a specific adhesive (Silorane System Adhesive, 3M ESPE), in particular because of the high hydrophobicity of the silorane composite. The purpose of this study was to characterize the interfacial ultra-structure at enamel and dentin using transmission electron microscopy (TEM). Non-demineralized/demineralized 70-90 nm sections were prepared following common TEM specimen processing procedures. TEM revealed a typical twofold build-up of the adhesive resin, resulting in a total adhesive layer thickness of 10-20 microm. At bur-cut enamel, a tight interface without distinct dissolution of hydroxyapatite was observed. At bur-cut dentin, a relatively thin hybrid layer of maximum a few hundreds of nanometer was formed without clear surface demineralization. No clear resin tags were formed. At fractured dentin, the interaction appeared very superficial (100-200 nm). Distinct resin tags were formed due to the absence of smear plugs. Silver-nitrate infiltration showed a varying pattern of both spot- and cluster-like appearance of nano-leakage. Traces of Ag were typically detected along some part of the enamel-adhesive interface and/or between the two adhesive resin layers. Substantially more Ag-infiltration was observed along the dentin-adhesive interface of bur-cut dentin, as compared to that of fractured dentin. The nano-interaction of Silorane System Adhesive should be attributed to its relatively high pH of 2.7. The obtained tight interface at both enamel and dentin indicates that the two-step self-etch adhesive effectively bridged the hydrophilic tooth substrate with the hydrophobic silorane composite. Copyright (c) 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

A Novel Role of Periostin in Postnatal Tooth Formation and Mineralization*

PubMed Central

Ma, Dedong; Zhang, Rong; Sun, Yao; Rios, Hector F.; Haruyama, Naoto; Han, Xianglong; Kulkarni, Ashok B.; Qin, Chunlin; Feng, Jian Q.

2011-01-01

Periostin plays multiple functions during development. Our previous work showed a critical role of this disulfide-linked cell adhesion protein in maintenance of periodontium integrity in response to occlusal load. In this study, we attempted to address whether this mechanical response molecule played a direct role in postnatal tooth development. Our key findings are 1) periostin is expressed in preodontoblasts, and odontoblasts; and the periostin-null incisor displayed a massive increase in dentin formation after mastication; 2) periostin is also expressed in the ameloblast cells, and an enamel defect is identified in both the adult-null incisor and molar; 3) deletion of periostin leads to changes in expression profiles of many non-collagenous protein such as DSPP, DMP1, BSP, and OPN in incisor dentin; 4) the removal of a biting force leads to reduction of mineralization, which is partially prevented in periostin-null mice; and 6) both in vitro and in vivo data revealed a direct regulation of periostin by TGF-β1 in dentin formation. In conclusion, periostin plays a novel direct role in controlling postnatal tooth formation, which is required for the integrity of both enamel and dentin. PMID:21131362

GaAlAs laser irradiation induces active tertiary dentin formation after pulpal apoptosis and cell proliferation in rat molars.

PubMed

Shigetani, Yoshimi; Sasa, Natsuki; Suzuki, Hironobu; Okiji, Takashi; Ohshima, Hayato

2011-08-01

This study aimed to clarify pulpal responses to gallium-aluminum-arsenide (GaAlAs) laser irradiation. Maxillary first molars of 8-week-old rats were irradiated at an output power of 0.5 or 1.5 W for 180 seconds, and the samples were collected at intervals of 0 to 14 days. The demineralized paraffin sections were processed for immunohistochemistry for heat-shock protein (HSP)-25 and nestin in addition to cell proliferation assay using bromodeoxyuridine (BrdU) labeling and apoptosis assay using deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling (TUNEL). Intense HSP-25 and nestin immunoreactivities in the odontoblast layer were weakened immediately after 0.5-W irradiation and recovered on day 1, resulting in slight tertiary dentin formation by day 14. On the contrary, 1.5-W irradiation immediately induced the loss of HSP-25 and nestin-immunoreactivities in the odontoblast layer. On day 1, numerous TUNEL-positive cells appeared in a degenerative zone that was surrounded by intense HSP-25 immunoreactivity. BrdU-positive cells occurred within the intensely HSP-25-immunopositive areas during days 2 through 5, whereas TUNEL-positive cells gradually decreased in number by day 5. HSP-25- and nestin-positive odontoblast-like cells were arranged along the pulp-dentin border by day 7, resulting in remarkable tertiary dentin formation on day 14. The output energy determined pulpal healing patterns after GaAlAs laser irradiation; the higher energy induced the apoptosis in the affected dental pulp including odontoblasts followed by active cell proliferation in the intense HSP-25-immunoreactive areas surrounding the degenerative tissue, resulting in abundant tertiary dentin formation. Thus, the optimal GaAlAs laser irradiation elicited intentional tertiary dentin formation in the dental pulp. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Contemporary research findings on dentine remineralization.

PubMed

Zhong, Bo; Peng, Ce; Wang, Guanhong; Tian, Lili; Cai, Qiang; Cui, Fuzhai

2015-09-01

Dentine remineralization is important for the treatment of dentine caries and the bonding durability of dentine and resin materials in clinical practice. Early studies of dentine remineralization were mostly based on the classical pathway of crystallization, which involves large-scale deposition of calcium phosphate crystals on collagen and is achieved in a liquid environment containing mineral ions. Results from these studies were unsatisfactory and not suitable for clinical application because they did not simulate the ordering of hydroxyapatite in the collagen fibres of natural teeth. As studies on collagen type I and non-collagenous proteins have advanced, dentine biomimetic remineralization has become a popular research topic and has shifted to processes involving intrafibrillar remineralization, which is more similar to natural tooth formation. The objective of this review was to summarize current theory and research progress as it relates to dentine remineralization. Copyright © 2013 John Wiley & Sons, Ltd.

Effect of fluoride on caries progression and dentin apposition in rats fed on a cariogenic or non-cariogenic diet.

PubMed

Kortelainen, S; Larmas, M

1993-02-01

The effect of fluoride in drinking water on the progression of dentinal caries and dentin apposition was studied in Wistar rats. The initiation of enamel caries lesions was first induced for 2 wk with S. sobrinus and a 43% sucrose diet after weaning. Thereafter the animals were fed on either a cariogenic or a non-cariogenic diet and distilled water supplemented with 0, 1, 7 or 19 ppm fluoride. The areas of dentinal caries and dentin apposition were quantified after tetracycline staining. Fluoride reduced dentinal caries progression after the initiation of lesions in the presence of a cariogenic diet at a concentration of 19 ppm F, and without sucrose at 1 ppm F. The effect of fluoride in reducing dentin apposition with a cariogenic diet was dose-dependent, whereas fluoride in non-cariogenic groups had practically no effect on dentin formation. These results suggest that fluoride together with a high concentration of sucrose in the diet might have an odontoblast-mediated effect on the regulation of the progression of dentinal caries.

Immunohistochemical localization of the NH(2)-terminal and COOH-terminal fragments of dentin sialoprotein in mouse teeth.

PubMed

Yuan, Guohua; Yang, Guobin; Song, Guangtai; Chen, Zhi; Chen, Shuo

2012-08-01

Dentin sialoprotein (DSP) is a major non-collagenous protein in dentin. Mutation studies in human, along with gene knockout and transgenic experiments in mice, have confirmed the critical role of DSP for dentin formation. Our previous study reported that DSP is processed into fragments in mouse odontoblast-like cells. In order to gain insights into the function of DSP fragments, we further evaluated the expression pattern of DSP in the mouse odontoblast-like cells using immunohistochemistry and western blot assay with antibodies against the NH(2)-terminal and COOH-terminal regions of DSP. Then, the distribution profiles of the DSP NH(2)-terminal and COOH-terminal fragments and osteopontin (OPN) were investigated in mouse teeth at different ages by immunohistochemistry. In the odontoblast-like cells, multiple low molecular weight DSP fragments were detected, suggesting that part of the DSP protein was processed in the odontoblast-like cells. In mouse first lower molars, immunoreactions for anti-DSP-NH(2) antibody were intense in the predentin matrix but weak in mineralized dentin; in contrast, for anti-DSP-COOH antibody, strong immunoreactions were found in mineralized dentin, in particular dentinal tubules but weak in predentin. Therefore, DSP NH(2)-terminal and COOH-terminal fragments from odontoblasts were secreted to different parts of teeth, suggesting that they may play distinct roles in dentinogenesis. Meanwhile, both DSP antibodies showed weak staining in reactionary dentin (RD), whereas osteopontin (OPN) was clearly positive in RD. Therefore, DSP may be less crucial for RD formation than OPN.

Immunohistochemical localization of the NH2-terminal and COOH-terminal fragments of dentin sialoprotein in mouse teeth

PubMed Central

Yuan, Guohua; Yang, Guobin; Song, Guangtai

2013-01-01

Dentin sialoprotein (DSP) is a major non-collagenous protein in dentin. Mutation studies in human, along with gene knockout and transgenic experiments in mice, have confirmed the critical role of DSP for dentin formation. Our previous study reported that DSP is processed into fragments in mouse odontoblast-like cells. In order to gain insights into the function of DSP fragments, we further evaluated the expression pattern of DSP in the mouse odontoblast-like cells using immunohistochemistry and western blot assay with antibodies against the NH2-terminal and COOH-terminal regions of DSP. Then, the distribution profiles of the DSP NH2-terminal and COOH-terminal fragments and osteopontin (OPN) were investigated in mouse teeth at different ages by immunohistochemistry. In the odontoblast-like cells, multiple low molecular weight DSP fragments were detected, suggesting that part of the DSP protein was processed in the odontoblast-like cells. In mouse first lower molars, immunoreactions for anti-DSP-NH2 antibody were intense in the predentin matrix but weak in mineralized dentin; in contrast, for anti-DSP-COOH antibody, strong immunoreactions were found in mineralized dentin, in particular dentinal tubules but weak in predentin. Therefore, DSP NH2-terminal and COOH-terminal fragments from odontoblasts were secreted to different parts of teeth, suggesting that they may play distinct roles in dentinogenesis. Meanwhile, both DSP antibodies showed weak staining in reactionary dentin (RD), whereas osteopontin (OPN) was clearly positive in RD. Therefore, DSP may be less crucial for RD formation than OPN. PMID:22581382

The narwhal (Monodon monoceros) cementum-dentin junction: a functionally graded biointerphase.

PubMed

Grandfield, Kathryn; Chattah, Netta Lev-Tov; Djomehri, Sabra; Eidelmann, Naomi; Eichmiller, Frederick C; Webb, Samuel; Schuck, P James; Nweeia, Martin; Ho, Sunita P

2014-08-01

In nature, an interface between dissimilar tissues is often bridged by a graded zone, and provides functional properties at a whole organ level. A perfect example is a "biological interphase" between stratified cementum and dentin of a narwhal tooth. This study highlights the graded structural, mechanical, and chemical natural characteristics of a biological interphase known as the cementum-dentin junction layer and their effect in resisting mechanical loads. From a structural perspective, light and electron microscopy techniques illustrated the layer as a wide 1000-2000 μm graded zone consisting of higher density continuous collagen fiber bundles from the surface of cementum to dentin, that parallels hygroscopic 50-100 μm wide collagenous region in human teeth. The role of collagen fibers was evident under compression testing during which the layer deformed more compared to cementum and dentin. This behavior is reflected through site-specific nanoindentation indicating a lower elastic modulus of 2.2 ± 0.5 GPa for collagen fiber bundle compared to 3 ± 0.4 GPa for mineralized regions in the layer. Similarly, microindentation technique illustrated lower hardness values of 0.36 ± 0.05 GPa, 0.33 ± 0.03 GPa, and 0.3 ± 0.07 GPa for cementum, dentin, and cementum-dentin layer, respectively. Biochemical analyses including Raman spectroscopy and synchrotron-source microprobe X-ray fluorescence demonstrated a graded composition across the interface, including a decrease in mineral-to-matrix and phosphate-to-carbonate ratios, as well as the presence of tidemark-like bands with Zn. Understanding the structure-function relationships of wider tissue interfaces can provide insights into natural tissue and organ function. © IMechE 2014.

Prevention of water-contamination of ethanol-saturated dentin and hydrophobic hybrid layers

PubMed Central

Sauro, Salvatore; Watson, Timothy F; Mannocci, Francesco; Tay, Franklin R; Pashley, David H

2013-01-01

SUMMARY Purpose This in vitro study evaluated the amount and the distribution of outward fluid flow that occurred when an experimental etch-and-rinse hydrophobic adhesive was applied to ethanol-saturated dentin before and after oxalate pretreatment. Materials and methods Measurements of dentin permeability were performed under a constant pulpal pressure of 20 cm H2O in deep and middle dentin. A lucifer yellow solution was placed in the pulp chamber to determine the distribution of the water contamination of the hybrid layers. Results The distribution of fluorescence in dentin specimens that were not pretreated with oxalate revealed that the dye permeated around the resin tags and filled the hybrid layer. Dentin specimens pretreated with oxalate prior to resin bonding, showed 80–83% less (p<0.05) water contamination compared to controls. The dentin permeability results obtained before and after oxalate pretreatment showed that oxalate decreased dentin permeability by 98% (p<0.05) compared to acid-etched controls. This prevented outward fluid movement during bonding resulting in better resin sealing of dentin due to the formation of a double seal of resin tags over calcium oxalate crystals in the tubules. Conclusion Outward dentinal fluid flow may contaminate hybrid layers during adhesive bonding procedures. Pretreatment of acid-etched dentin with 3% oxalic acid prior to bonding procedures can prevent outward fluid flow during bonding and water contamination of the hydrophobic hybrid layers. PMID:19701507

Dentine sialoprotein and collagen I expression after experimental pulp capping in humans using emdogain gel.

PubMed

Fransson, H; Petersson, K; Davies, J R

2011-03-01

To characterize the hard tissue formed in human teeth experimentally pulp capped either with calcium hydroxide or with Emdogain Gel (Biora AB, Malmö, Sweden) - a derivative of enamel matrix (EMD), using two markers for dentine; dentine sialoprotein (DSP) and type 1 collagen (Col I). Affinity-purified rabbit anti-Col I and anti-DSP polyclonal antibodies were used to stain histological sections from nine pairs of contra-lateral premolars that had been experimentally pulp amputated and randomly capped with EMDgel or calcium hydroxide. Twelve weeks after the teeth had been pulp capped, they were extracted, fixed, demineralized and serially sectioned prior to immunohistochemical staining. In the calcium hydroxide treated teeth DSP was seen in the new hard tissue which formed a bridge. DSP was also seen in the newly formed hard tissue in the EMDgel-treated teeth. Proliferated pulp tissue partly filled the space initially occupied by EMDgel and DSP-stained hard tissue was observed alongside exposed dentine surfaces as well as in isolated masses within the proliferated pulp tissue, although the new hard tissue did not cover the pulp exposure. DSP staining was also seen in the cells lining the hard tissue in both groups. Col I staining was seen in the newly formed hard tissue in both groups. The new hard tissue formed after pulp capping with EMDgel or calcium hydroxide contained DSP and Col I, considered to be markers for dentine. Thus, the newly formed hard tissue can be characterized as dentine rather than unspecific hard tissue. © 2010 International Endodontic Journal.

Clinical and radiographic comparison of indirect pulp treatment using light-cured calcium silicate and mineral trioxide aggregate in primary molars: A randomized clinical trial.

PubMed

Menon, Navya P; Varma, Balagopal R; Janardhanan, Sureshkumar; Kumaran, Parvathy; Xavier, Arun Mamachan; Govinda, Bhat Sangeetha

2016-01-01

To clinically and radiographically evaluate the reparative dentin formation in indirect pulp treatment (IPT) using mineral trioxide aggregate (MTA) and light cured calcium silicate (TheraCal) in primary molars over a period of 6 months. A clinical trial on IPT on 43 primary molars in 21 patients between the age of 4-7 years, divided into two groups: 22 teeth in MTA group and 21 in TheraCal group. Measurement of the variation in dentin thickness was done on the digitalized radiograph at baseline, 3 months and 6 months using CorelDRAW X3 software. Statistical analysis using an independent t -test for intragroup and intergroup comparison showed a significant increase in dentin thickness in both the MTA and TheraCal group (intragroup comparison [ P < 0.05]). However, intergroup comparison between MTA and TheraCal showed no statistical difference in reparative dentin formation ( P > 0.05). Clinically and radiographically, both MTA and TheraCal are good IPT materials. The better handling characteristics and comparable reparative dentin-forming ability of TheraCal make this material an alternative to MTA in pediatric restorative procedures.

Dental Pulp Defence and Repair Mechanisms in Dental Caries

PubMed Central

Farges, Jean-Christophe; Alliot-Licht, Brigitte; Renard, Emmanuelle; Ducret, Maxime; Gaudin, Alexis; Smith, Anthony J.; Cooper, Paul R.

2015-01-01

Dental caries is a chronic infectious disease resulting from the penetration of oral bacteria into the enamel and dentin. Microorganisms subsequently trigger inflammatory responses in the dental pulp. These events can lead to pulp healing if the infection is not too severe following the removal of diseased enamel and dentin tissues and clinical restoration of the tooth. However, chronic inflammation often persists in the pulp despite treatment, inducing permanent loss of normal tissue and reducing innate repair capacities. For complete tooth healing the formation of a reactionary/reparative dentin barrier to distance and protect the pulp from infectious agents and restorative materials is required. Clinical and in vitro experimental data clearly indicate that dentin barrier formation only occurs when pulp inflammation and infection are minimised, thus enabling reestablishment of tissue homeostasis and health. Therefore, promoting the resolution of pulp inflammation may provide a valuable therapeutic opportunity to ensure the sustainability of dental treatments. This paper focusses on key cellular and molecular mechanisms involved in pulp responses to bacteria and in the pulpal transition between caries-induced inflammation and dentinogenic-based repair. We report, using selected examples, different strategies potentially used by odontoblasts and specialized immune cells to combat dentin-invading bacteria in vivo. PMID:26538821

Dental Pulp Defence and Repair Mechanisms in Dental Caries.

PubMed

Farges, Jean-Christophe; Alliot-Licht, Brigitte; Renard, Emmanuelle; Ducret, Maxime; Gaudin, Alexis; Smith, Anthony J; Cooper, Paul R

2015-01-01

Dental caries is a chronic infectious disease resulting from the penetration of oral bacteria into the enamel and dentin. Microorganisms subsequently trigger inflammatory responses in the dental pulp. These events can lead to pulp healing if the infection is not too severe following the removal of diseased enamel and dentin tissues and clinical restoration of the tooth. However, chronic inflammation often persists in the pulp despite treatment, inducing permanent loss of normal tissue and reducing innate repair capacities. For complete tooth healing the formation of a reactionary/reparative dentin barrier to distance and protect the pulp from infectious agents and restorative materials is required. Clinical and in vitro experimental data clearly indicate that dentin barrier formation only occurs when pulp inflammation and infection are minimised, thus enabling reestablishment of tissue homeostasis and health. Therefore, promoting the resolution of pulp inflammation may provide a valuable therapeutic opportunity to ensure the sustainability of dental treatments. This paper focusses on key cellular and molecular mechanisms involved in pulp responses to bacteria and in the pulpal transition between caries-induced inflammation and dentinogenic-based repair. We report, using selected examples, different strategies potentially used by odontoblasts and specialized immune cells to combat dentin-invading bacteria in vivo.

Mechanical characterization of proanthocyanidin-dentin matrix interaction

PubMed Central

Castellan, Carina Strano; Pereira, Patricia Nobrega; Grande, Rosa Helena Miranda; Bedran-Russo, Ana Karina

2010-01-01

Objectives To characterize the properties of dentin matrix treated with two proanthocyanidin rich cross-linking agents and their effect on dentin bonded interfaces. Methods Sound human molars were cut into 0.5 mm thick dentin slabs, demineralized and either treated with one of two cross-linking agents (grape seed - GSE and cocoa seed - COE extracts) or left untreated. The modulus of elasticity of demineralized dentin was assessed after 10 or 60 min and the swelling ratio after 60 min treatment. Bacterial collagenase was also used to assess resistance to enzymatic degradation of samples subjected to ultimate tensile strength. The effect of GSE or COE on the resin-dentin bond strength was evaluated after 10 or 60 min of exposure time. Data were statistically analyzed at a 95% confidence interval. Results Both cross-linkers increased the elastic modulus of demineralized dentin as exposure time increased. Swelling ratio was lower for treated samples when compared to control groups. No statistically significant changes to the UTS indicate that collagenase had no effect on dentin matrix treated with either GSE or COE. Dentin-resin bonds significantly increased following treatment with GSE regardless of the application time or adhesive system used. Significance Increased mechanical properties and stability of dentin matrix can be achieved by the use of PA-rich collagen cross-linkers most likely due to the formation of a PA-collagen complex. The short term dentin-resin bonds can be improved after 10 minutes dentin treatment. PMID:20650510

Biomimetic remineralization of dentin

PubMed Central

Niu, Li-na; Zhang, Wei; Pashley, David H.; Breschi, Lorenzo; Mao, Jing; Chen, Ji-hua; Tay, Franklin R.

2013-01-01

Objectives Remineralization of demineralized dentin is important for improving dentin bonding stability and controlling primary and secondary caries. Nevertheless, conventional dentin remineralization strategy is not suitable for remineralizing completely-demineralized dentin within hybrid layers created by etch-and-rinse and moderately aggressive self-etch adhesive systems, or the superficial part of a caries-affected dentin lesion left behind after minimally invasive caries removal. Biomimetic remineralization represents a different approach to this problem by attempting to backfill the demineralized dentin collagen with liquid-like amorphous calcium phosphate nanoprecursor particles that are stabilized by biomimetic analogs of noncollagenous proteins. Methods This paper reviewed the changing concepts in calcium phosphate mineralization of fibrillar collagen, including the recently discovered, non-classical particle-based crystallization concept, formation of polymer-induced liquid- precursors (PILP), experimental collagen models for mineralization, and the need for using phosphate-containing biomimetic analogs for biomimetic mineralization of collagen. Published work on the remineralization of resin-dentin bonds and artificial caries-like lesions by various research groups was then reviewed. Finally, the problems and progress associated with the translation of a scientifically-sound concept into a clinically-applicable approach are discussed. Results and Significance The particle-based biomimetic remineralization strategy based on the PILP process demonstrates great potential in remineralizing faulty hybrid layers or caries-like dentin. Based on this concept, research in the development of more clinically feasible dentin remineralization strategy, such as incorporating poly(anionic) acid-stabilized amorphous calcium phosphate nanoprecursor-containing mesoporous silica nanofillers in dentin adhesives, may provide a promising strategy for increasing of the durability of resin-dentin bonding and remineralizing caries-affected dentin. PMID:23927881

Colocalization of dentin matrix protein 1 and dentin sialoprotein at late stages of rat molar development.

PubMed

Baba, Otto; Qin, Chunlin; Brunn, Jan C; Wygant, James N; McIntyre, Bradley W; Butler, William T

2004-10-01

Dentin matrix protein 1 (DMP1) and dentin sialophosphoprotein (DSPP) are acidic proteins found in the extracellular matrices of bones and teeth. Recent data from gene knockouts, along with those of gene mutations, indicate that these two phosphoproteins are critical for bone and tooth development and/or maintenance. However, the precise functions of the two proteins have not been elucidated. In order to gain insights into their functions in tooth formation, we performed systematic, comparative investigations on the immunolocalization of DMP1 and dentin sialoprotein (DSP, a cleaved fragment of DSPP), using the rat first molar at different developmental stages as a model. Immunohistochemistry (IHC) was performed with specific, monoclonal antibodies against the COOH-terminal fragments of DMP1 and against DSP. In 1-day- and 1-week-old rats, weak immunoreactions for DMP1 were observed in dentinal tubules while stronger reactions for DSP were seen in the tubules and predentin. In rats older than 2 weeks, immunoreactions for DMP1 were found in dentinal tubules, predentin and odontoblasts. In 5-week- and 8-week-old rats, strong immunoreactions for DMP1 were widely distributed in odontoblasts and predentin. The distribution pattern of DSP was strikingly similar to that of DMP1 after 2 weeks and the localization of each was distinctly different from that of bone sialoprotein (BSP). The unique colocalization of DMP1 and DSPP in tooth development suggests that the two proteins play complementary and/or synergistic roles in formation and maintenance of healthy teeth.

A new procedure for processing extracted teeth for immediate grafting in post-extraction sockets. An experimental study in American Fox Hound dogs.

PubMed

Calvo-Guirado, José Luis; Cegarra Del Pino, Pilar; Sapoznikov, Lari; Delgado Ruiz, Rafael Arcesio; Fernández-Domínguez, Manuel; Gehrke, Sérgio Alexandre

2018-05-01

To investigate freshly extracted dental particulate used to graft post-extraction sockets in dogs, comparing new bone formation at experimental and control sites. Bilateral premolars P2, P3, P4 and first mandibular molars were extracted atraumatically from six American Fox Hound dogs. The teeth were ground immediately using a 'Smart Dentin Grinder'. The dentin particulate was sieved to ensure a grain size of 300-1200μm and immersed in an alcohol cleanser to dissolve organic debris and bacteria, followed by washing in sterile saline buffer solution. The animals were divided into two groups randomly: group 'A' (control) samples were left to heal without any extraction socket grafting procedure; group 'B' (experimental) sockets were filled with the autogenous dentin particulate graft. The rate of tissue healing and the quantity of bone formation were evaluated using histological and histomorphometric analyses at 60 and 90 days post-grafting. The type of bone generated was categorized as woven (immature bone) or lamellar bone (mature bone). Substantially more bone formation was found in Group B (experimental) than Group A (control) at 60 and 90 days (p<0.05). Less immature bone was identified in the dentin grafted group (25.7%) than the control group (5.9%). Similar differences were also observed at 90 days post grafting. Autogenous dentin particulate grafted immediately after extractions may be considered a useful biomaterial for socket preservation, protecting both buccal and lingual plates, generating large amounts of new woven bone formation after 60 days, and small amounts of lamellar bone after 90 days healing. Copyright © 2018 Elsevier GmbH. All rights reserved.

Comparative morphology, histology and growth of the dental plates of the Devonian dipnoan Chirodipterus.

PubMed

Smith, M M; Campbell, K S

1987-10-14

The dental plates of the Devonian lungfish Chirodipterus australis Miles (Osteichthyes; Dipnoi) are shown to have achieved their characteristic morphology by a growth process different from that assumed for the plates of genera such as Dipterus. Each plate was thickened by the addition of layers of bone that also extended the plate labially, thus providing the base on which and into which dentine grew. Distinctive features of the dentition are: (a) labial increase of the dentine mass by the addition of blister-like denticles of simple enamel-covered dentine, which is initially ingrown by pleromic dentine and subsequently resorbed and replaced by petrodentine; (b) increase in the midline by a similar process that results in the addition of one (or possibly two) new ridges; (c) resorption of the posterior edge of the pterygoid plates and the posterior and posteromedial edges of the prearticular plates, with subsequent development over the resorbed surfaces of several generations of simple regenerative dentine; (d) resorption and redeposition of pleromic dentine and bone in a triangular region posteromedially on the pterygoid plates; (e) the formation of tuberosities that simulate teeth at a short distance in from the labial edge, by four processes: formation of an undulating plate margin, differential growth of petrodentine (hard compact dentine) within the pulp cavity, differential wear of the petrodentine and the adjacent bone plus pleromic dentine, and slightly greater growth of the petrodentine towards the occlusal surface relative to the adjacent bone and dentine; (f) expansion of the large flat surfaces of the plates by gradual replacement of the bone and dentine at the proximal ends of the furrows and also by the development of linkages of petrodentine across the furrows; (g) development of isolated tuberosities on the flat posterolateral parts of the plates. The petrodentine of the ridges, tuberosities and plateaus of the plates is indistinguishable structurally and in its mode of growth from the petrodentine in extant species of dipnoans. Plates similar to those of C. australis have been observed in Stomiahykus, Archaeonectes, Conchodus, Palaedaphus and Sunwapta, as well as several species usually referred to as Dipterus. Sunwapta may be congeneric with C. australis.(ABSTRACT TRUNCATED AT 400 WORDS)

Influences of the cold atmospheric plasma jet treatment on the properties of the demineralized dentin surfaces

NASA Astrophysics Data System (ADS)

Xiaoming, ZHU; Heng, GUO; Jianfeng, ZHOU; Xiaofei, ZHANG; Jian, CHEN; Jing, LI; Heping, LI; Jianguo, TAN

2018-04-01

Improvement of the bonding strength and durability between the dentin surface and the composite resin is a challenging job in dentistry. In this paper, a radio-frequency atmospheric-pressure glow discharge (RF-APGD) plasma jet is employed for the treatment of the acid-etched dentin surfaces used for the composite restoration. The properties of the plasma treated dentin surfaces and the resin-dentin interfaces are analyzed using the x-ray photoemission spectroscopy, contact angle goniometer, scanning electron microscope and microtensile tester. The experimental results show that, due to the abundant chemically reactive species existing in the RF-APGD plasma jet under a stable and low energy input operating mode, the contact angle of the plasma-treated dentin surfaces decreases to a stable level with the increase of the atomic percentage of oxygen in the specimens; the formation of the long resin tags in the scattered clusters and the hybrid layers at the resin-dentin interfaces significantly improve the bonding strength and durability. These results indicate that the RF-APGD plasma jet is an effective tool for modifying the chemical properties of the dentin surfaces, and for improving the immediate bonding strength and the durability of the resin-dentin bonding in dentistry.

Glutaraldehyde-induced remineralization improves the mechanical properties and biostability of dentin collagen.

PubMed

Chen, Chaoqun; Mao, Caiyun; Sun, Jian; Chen, Yi; Wang, Wei; Pan, Haihua; Tang, Ruikang; Gu, Xinhua

2016-10-01

The purpose of this study was to induce a biomimetic remineralization process by using glutaraldehyde (GA) to reconstruct the mechanical properties and biostability of demineralized collagen. Demineralized dentin disks (35% phosphoric acid, 10s) were pretreated with a 5% GA solution for 3min and then cultivated in a calcium phosphate remineralization solution. The remineralization kinetics and superstructure of the remineralization layer were evaluated by Raman spectroscopy, transmission electron microscopy, scanning electron microscopy and nanoindentation tests. The biostability was examined by enzymatic degradation experiments. A significant difference was found in dentin remineralization process between dentin with and without GA pretreating. GA showed a specific affinity to dentin collagen resulting in the formation of a cross-linking superstructure. GA pretreating could remarkably shorten remineralization time from 7days to 2days. The GA-induced remineralized collagen fibrils were well encapsulated by newly formed hydroxyapatite mineral nanocrystals. With the nano-hydroxyapatite coating, both the mechanical properties (elastic modulus and hardness) and the biostability against enzymatic degradation of the collagen were significantly enhanced, matching those of natural dentin. The results indicated that GA cross-linking of dentin collagen could promote dentin biomimetic remineralization, resulting in an improved mechanical properties and biostability. It may provide a promising tissue-engineering technology for dentin repair. Copyright © 2016 Elsevier B.V. All rights reserved.

Shear bond strengths of self-etching adhesives to caries-affected dentin on the gingival wall.

PubMed

Koyuturk, Alp Erdin; Sengun, Abdulkadir; Ozer, Fusun; Sener, Yagmur; Gokalp, Alparslan

2006-03-01

The purpose of this study was to evaluate the bonding ability of five current self-etching adhesives to caries-affected dentin on the gingival wall. Seventy extracted human molars with approximal dentin caries were employed in this study. In order to obtain caries-affected dentin on the gingival wall, grinding was performed under running water. Following which, specimens mounted in acrylic blocks and composite resins of the bonding systems were bonded to dentin with plastic rings and then debonded by shear bond strength. With Clearfil SE Bond, bonding to caries-affected dentin showed the highest bond strength. With Optibond Solo Plus Self-Etch, bonding to caries-affected dentin showed higher shear bond strength than AQ Bond, Tyrian SPE & One-Step Plus, and Prompt-L-Pop (p<0.05). Further, the bond strengths of Clearfil SE Bond and Optibond Solo Plus Self-Etch to sound dentin were higher than those of Prompt-L-Pop, AQ Bond, and Tyrian SPE & One-Step Plus (p<0.05). In conclusion, besides micromechanical interlocking through hybrid layer formation, bond strength of self-etch adhesives to dentin may be increased from additional chemical interaction between the functional monomer and residual hydroxyapatite. The results of this study confirmed that differences in bond strength among self-etching adhesives to both caries-affected and sound dentin were due to chemical composition rather than acidity.

Fabrication and characterization of dendrimer-functionalized nano-hydroxyapatite and its application in dentin tubule occlusion.

PubMed

Lin, Xuandong; Xie, Fangfang; Ma, Xueling; Hao, Yuhong; Qin, Hejia; Long, Jindong

2017-06-01

The occlusion of dentinal tubules is an effective method to alleviate the symptoms of dentin hypersensitivity. In this paper, we successfully modified nano-hydroxyapatite (n-HAP) with carboxyl-terminated polyamidoamine dendrimers by an aqueous-based chemical method and verified by fourier transform infrared spectroscopy (FTIR) and transmission electron microscope (TEM). Then the demineralization dentin discs were randomly divided into 4 groups, corresponding to subsequent brushing experiments: deionized water and kept in artificial saliva (AS), dendrimer-functionalized n-HAP and stored in AS, n-HAP and saved in AS, dendrimer-functionalized n-HAP and stored in deionized water. After 7 days of simulated brushing, dentin discs followed the in vitro characterization using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy and microhardness test. These data suggested that dendrimer-functionalized n-HAP could crosslink with collagen fibers and resulted in effective dentinal tubule occlusion. Moreover, the new material can induce the HAP formation with the help of superficial carboxyl and fill the spaces in dentinal tubules furtherly. The microhardness of dendrimer-functionalized n-HAP-treated specimens was significantly higher than others. In summary, dendrimer-functionalized n-HAP can be a new therapeutic material for the treatment of dentin hypersensitivity.

Biomimetic remineralization of dentin.

PubMed

Niu, Li-Na; Zhang, Wei; Pashley, David H; Breschi, Lorenzo; Mao, Jing; Chen, Ji-Hua; Tay, Franklin R

2014-01-01

Remineralization of demineralized dentin is important for improving dentin bonding stability and controlling primary and secondary caries. Nevertheless, conventional dentin remineralization strategy is not suitable for remineralizing completely demineralized dentin within hybrid layers created by etch-and-rinse and moderately aggressive self-etch adhesive systems, or the superficial part of a caries-affected dentin lesion left behind after minimally invasive caries removal. Biomimetic remineralization represents a different approach to this problem by attempting to backfill the demineralized dentin collagen with liquid-like amorphous calcium phosphate nanoprecursor particles that are stabilized by biomimetic analogs of noncollagenous proteins. This paper reviewed the changing concepts in calcium phosphate mineralization of fibrillar collagen, including the recently discovered, non-classical particle-based crystallization concept, formation of polymer-induced liquid-precursors (PILP), experimental collagen models for mineralization, and the need for using phosphate-containing biomimetic analogs for biomimetic mineralization of collagen. Published work on the remineralization of resin-dentin bonds and artificial caries-like lesions by various research groups was then reviewed. Finally, the problems and progress associated with the translation of a scientifically sound concept into a clinically applicable approach are discussed. The particle-based biomimetic remineralization strategy based on the PILP process demonstrates great potential in remineralizing faulty hybrid layers or caries-like dentin. Based on this concept, research in the development of more clinically feasible dentin remineralization strategy, such as incorporating poly(anionic) acid-stabilized amorphous calcium phosphate nanoprecursor-containing mesoporous silica nanofillers in dentin adhesives, may provide a promising strategy for increasing of the durability of resin-dentin bonding and remineralizing caries-affected dentin. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Ultrastructural properties of laser-irradiated and heat-treated dentin.

PubMed

Rohanizadeh, R; LeGeros, R Z; Fan, D; Jean, A; Daculsi, G

1999-12-01

Previous studies using scanning electron microscopy and infrared absorption spectroscopy reported that laser irradiation causes compositional changes in enamel. The purpose of this study was to evaluate the ultrastructural and compositional changes in dentin caused by irradiation with a short-pulse laser (Q-switched Nd:YAG). The irradiated and non-irradiated areas of the lased dentin samples were investigated by scanning (SEM) and transmission electron microscopy (TEM), micro-micro electron diffraction, and electron microprobe analysis of dispersive energy (EDX). Heat-treated dentin was similarly investigated. This study demonstrated that laser irradiation resulted in the recrystallization of dentin apatite and in the formation of additional calcium phosphate phases consisting of magnesium-substituted beta-tricalcium phosphate, beta-TCMP, beta-(Ca,Mg)3(PO4)2, and tetracalcium phosphate, TetCP, Ca4(PO4)O. TEM analyses of the modified and unmodified zones of the irradiated areas showed two types of crystal populations: much larger crystals from the modified zone and crystals with size and morphology similar to those of dentin apatite in the unmodified zone. The morphology of crystals in the modified zones in the irradiated dentin resembled those of dentin sintered at 800 or 950 degrees C. In the irradiated areas (modified and unmodified zones), the Ca/P ratio was lower compared with that in the non-irradiated dentin. The Mg/Ca ratio in the modified zones was higher than that in the unmodified zones and in the non-irradiated dentin. In sintered dentin, the Mg/Ca ratio increased as a function of sintering temperature. The ultrastructural and compositional changes observed in laser-irradiated dentin may be attributed to high temperature and high pressure induced by microplasma during laser irradiation. These changes may alter the solubility of the irradiated dentin, making it less susceptible to acid dissolution or to the caries process.

Dentin and pulp sense cold stimulus.

PubMed

Tokuda, Masayuki; Tatsuyama, Shoko; Fujisawa, Mari; Morimoto-Yamashita, Yoko; Kawakami, Yoshiko; Shibukawa, Yoshiyuki; Torii, Mistuso

2015-05-01

Dentin hypersensitivity is a common symptom, and recent convergent evidences have reported transient receptor potential (TRP) channels in odontoblasts act as mechanical and thermal molecular sensor, which detect stimulation applied on the exposed dentin surface, to drive multiple odontoblastic cellular functions, such as sensory transduction and/or dentin formation. In the present study, we confirmed expression of TRP melastatin subfamily member-8 (TRPM8) channels in primary cultured cells derived from human dental pulp cells (HPCs) and mouse odontoblast-lineage cells (OLCs) as well as in dentin matrix protein-1 (DMP-1) and dentin sialoprotein (DSP) positive acutely isolated rat odontoblasts from dental pulp tissue slice culture by immunohistochemical analyses. In addition, we detected TRPM8 channel expression on HPCs and OLCs by RT-PCR and Western blotting analyses. These results indicated that both odontoblasts and dental pulp cells express TRPM8 channels in rat, mouse and human, and therefore we hypothesize they may contribute as cold sensor in tooth. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mixed-mode stress intensity factors for kink cracks with finite kink length loaded in tension and bending: application to dentin and enamel.

PubMed

Bechtle, Sabine; Fett, Theo; Rizzi, Gabriele; Habelitz, Stefan; Schneider, Gerold A

2010-05-01

Fracture toughness resistance curves describe a material's resistance against crack propagation. These curves are often used to characterize biomaterials like bone, nacre or dentin as these materials commonly exhibit a pronounced increase in fracture toughness with crack extension due to co-acting mechanisms such as crack bridging, crack deflection and microcracking. The knowledge of appropriate stress intensity factors which depend on the sample and crack geometry is essential for determining these curves. For the dental biomaterials enamel and dentin it was observed that, under bending and tensile loading, crack propagation occurs under certain constant angles to the initial notch direction during testing procedures used for fracture resistance curve determination. For this special crack geometry (a kink crack of finite length in a finite body) appropriate geometric function solutions are missing. Hence, we present in this study new mixed-mode stress intensity factors for kink cracks with finite kink length within samples of finite dimensions for two loading cases (tension and bending) which were derived from a combination of mixed-mode stress intensity factors of kink cracks with infinitely small kinks and of slant cracks. These results were further applied to determine the fracture resistance curves of enamel and dentin by testing single edge notched bending (SENB) specimens. It was found that kink cracks with finite kink length exhibit identical stress fields to slant cracks as soon as the kink length exceeds 0.15 times the initial straight crack or notch length. The use of stress intensity factor solutions for infinitely small kink cracks for the determination of dentin fracture resistance curves (as was done by other researchers) leads to an overestimation of dentin's fracture resistance of up to 30%. Copyright 2010 Elsevier Ltd. All rights reserved.

[Biocompatibility of crown and bridge materials. 1. Substances in contact with dentin].

PubMed

Klotzer, W T

1989-11-01

It is mandatory that the materials and drugs used in restorative dentistry be free from side effects resulting in potential tooth loss or irreversible damage to vital dental tissues. Up to now there have been no reliable in vitro methods available for the evaluation of pulp reactions. Since numerous different materials and drugs are successively applied to prepared dentine, pulp reactions are caused by cumulative action, and the causative factors, except for extremely toxic substances, cannot be revealed by clinical and/or posttreatment studies alone. At present, the evaluation of pulp reactions must still rely on histologic studies using human or animal teeth. Reports on pulp reactions to materials and drugs are reviewed. Few dependable figures have been reported on pulp reactions to dentinal medication, "sterilization", disinfectants and on the biologic response to and effectiveness of varnishes, liners, desensitizing agents, smear-layer removers, etc. Resins and composite materials seem to provoke acute reactions, mainly by the heat generated during setting, and chronic reactions due to the stimulation of bacterial growth. Except for glass ionomer cements, most of the publications show a high degree of agreement on the tissue reactions to luting agents. Regarding dentine bonding agents, however, it has not been possible to draw any conclusions, so far.

Effect of low-level laser therapy (λ780 nm) on the mechanically damaged dentin-pulp complex in a model of extrusive luxation in rat incisors.

PubMed

de Santana, Dandara Andrade; Fonseca, Gabriela Ferraz; Ramalho, Luciana Maria Pedreira; Rodriguez, Tânia Tavares; Aguiar, Marcio Cajazeira

2017-12-01

In order to regenerate the dental pulp, many strategies have been developed as phototherapy. In the pulp repair, we do not know if gallium-aluminum-arsenide (GaAlAs) laser preserves the primary odontoblasts or stimulates the formation of more dentin matrix when dental pulp is damaged. The aim of the present study was to examine the effect of laser phototherapy (λ780 nm) on vascularization, inflammation, density of the primary odontoblast layer, and formation of reactionary and reparative dentin in the dental pulp by provoking extrusion of the rat incisor. The upper incisors were extruded 3 mm and then repositioned into their original sockets followed by a laser irradiation of the palatal mucosa (λ = 780 nm; p = 70 mW; CW; 4.2 J/cm 2 ; 60 s) every 48 h. Non-traumatized and/or non-irradiated incisors were used as the controls. At 8 and 30 days after surgery, incisors were processed for histological and histomorphometric analysis. Morphological analysis revealed no differences in vascularization between groups, but showed discrete inflammation in some non-irradiated and injured specimens, which correlated with a more irregular reparative dentin. The density of primary odontoblasts in the groups treated with lasers was higher when compared to non-irradiated groups, but no statistically significant difference between groups (p > 0.05). The thickness of the tertiary dentin was increased in both traumatized groups with no statistically significant difference between non-irradiated and irradiated groups (p > 0.05).The present findings revealed that the GaAlAs laser induced small changes on dentin-pulp complex, with more regular dentin matrix in the irradiated dental pulps.

EDTA conditioning of dentine promotes adhesion, migration and differentiation of dental pulp stem cells.

PubMed

Galler, K M; Widbiller, M; Buchalla, W; Eidt, A; Hiller, K-A; Hoffer, P C; Schmalz, G

2016-06-01

To evaluate the effect of dentine conditioning on migration, adhesion and differentiation of dental pulp stem cells. Dentine discs prepared from extracted human molars were pre-treated with EDTA (10%), NaOCl (5.25%) or H2 O. Migration of dental pulp stem cells towards pre-treated dentine after 24 and 48 h was assessed in a modified Boyden chamber assay. Cell adhesion was evaluated indirectly by measuring cell viability. Expression of mineralization-associated genes (COL1A1, ALP, BSP, DSPP, RUNX2) in cells cultured on pre-treated dentine for 7 days was determined by RT-qPCR. Nonparametric statistical analysis was performed for cell migration and cell viability data to compare different groups and time-points (Mann-Whitney U-test, α = 0.05). Treatment of dentine with H2 O or EDTA allowed for cell attachment, which was prohibited by NaOCl with statistical significance (P = 0.000). Furthermore, EDTA conditioning induced cell migration towards dentine. The expression of mineralization-associated genes was increased in dental pulp cells cultured on dentine after EDTA conditioning compared to H2 O-pre-treated dentine discs. EDTA conditioning of dentine promoted the adhesion, migration and differentiation of dental pulp stem cells towards or onto dentine. A pre-treatment with EDTA as the final step of an irrigation protocol for regenerative endodontic procedures has the potential to act favourably on new tissue formation within the root canal. © 2015 International Endodontic Journal. Published by John Wiley & Sons Ltd.

In situ gold nanoparticles formation: contrast agent for dental optical coherence tomography

NASA Astrophysics Data System (ADS)

Braz, Ana K. S.; Araujo, Renato E. de; Ohulchanskyy, Tymish Y.; Shukla, Shoba; Bergey, Earl J.; Gomes, Anderson S. L.; Prasad, Paras N.

2012-06-01

In this work we demonstrate the potential use of gold nanoparticles as contrast agents for the optical coherence tomography (OCT) imaging technique in dentistry. Here, a new in situ photothermal reduction procedure was developed, producing spherical gold nanoparticles inside dentinal layers and tubules. Gold ions were dispersed in the primer of commercially available dental bonding systems. After the application and permeation in dentin by the modified adhesive systems, the dental bonding materials were photopolymerized concurrently with the formation of gold nanoparticles. The gold nanoparticles were visualized by scanning electron microscopy (SEM). The SEM images show the presence of gold nanospheres in the hybrid layer and dentinal tubules. The diameter of the gold nanoparticles was determined to be in the range of 40 to 120 nm. Optical coherence tomography images were obtained in two- and three-dimensions. The distribution of nanoparticles was analyzed and the extended depth of nanosphere production was determined. The results show that the OCT technique, using in situ formed gold nanoparticles as contrast enhancers, can be used to visualize dentin structures in a non-invasive and non-destructive way.

Implant-based oral rehabilitation of a variant model of type I dentinal dysplasia: A rare case report

PubMed Central

Nettem, Sowmya; Nettemu, Sunil Kumar; Basha, K.; Venkatachalapathi, S

2014-01-01

Dentin dysplasia is an exceptionally rare, autosomal-dominant, hereditary condition, primarily characterized by defective dentin formation affecting both the deciduous and permanent dentitions. The etiology remains imprecise to date, in spite of the numerous hypotheses put forward and the constant updates on this condition. This case report of type I dentin dysplasia exhibits radiographic findings that are unique and diverse from the classical findings of various subtypes of this disease reported to date. This article also depicts the implant-based oral rehabilitation of the young patient diagnosed with this variant model of dentin dysplasia type I. Early diagnosis and implementation of this preventive and curative therapy is vital for avoiding premature exfoliation of deciduous and permanent dentition and the associated residual ridge resorption, thereby overcoming functional and esthetic deficits and ensuring protection of the remaining dentition from further harm. PMID:25225567

The effects of spaceflight on the mineralization of rat incisor dentin

NASA Technical Reports Server (NTRS)

Simmons, D. J.; Rosenberg, G. D.

1984-01-01

Specific effects of space flight on dentin formation on the lower incisors of male rats were determined. Data were Fourier analyzed to determine the spectra of chemical growth rhythms. It was found that Calcium and P were more concentrated in the newly forming dentin of the Flight rats than in comparable regions of control tissues. There was no significant difference in the mean S-concentration between the two groups, but the pattern of S-distribution in the recently formed dentin from the Flight rats was different from that in the control group. Sulfur fluctuations in flight animals periodically peak above the irregular background fluctuations, but there are no comparable sulfur peaks across the dentin in the control. It is indicated that spaceflight has measurable effects on dentinogenesis, and may also bear on the problem of the regulatory role of proteoglycans in mineralization and the maturation of mineral and matrix moieties in skeletal tissue.

Optical changes of dentin in the near-IR as a function of mineral content

NASA Astrophysics Data System (ADS)

Berg, Rhett A.; Simon, Jacob C.; Fried, Daniel; Darling, Cynthia L.

2017-02-01

The optical properties of human dentin can change markedly due to aging, friction from opposing teeth, and acute trauma, resulting in the formation of transparent or sclerotic dentin with increased mineral density. The objective of this study was to determine the optical attenuation coefficient of human dentin tissues with different mineral densities in the near-infrared (NIR) spectral regions from 1300-2200 nm using NIR transillumination and optical coherence tomography (OCT). N=50 dentin samples of varying opacities were obtained by sectioning whole extracted teeth into 150 μm transverse sections at the cemento-enamel junction or the apical root. Transillumination images were acquired with a NIR camera and attenuation measurements were acquired at various NIR wavelengths using a NIR sensitive photodiode. Samples were imaged with transverse microradiography (gold standard) in order to determine the mineral density of each sample.

Osteoclasts on bone and dentin in vitro: mechanism of trail formation and comparison of resorption behavior.

PubMed

Rumpler, M; Würger, T; Roschger, P; Zwettler, E; Sturmlechner, I; Altmann, P; Fratzl, P; Rogers, M J; Klaushofer, K

2013-12-01

The main function of osteoclasts in vivo is the resorption of bone matrix, leaving behind typical resorption traces consisting of pits and trails. The mechanism of pit formation is well described, but less is known about trail formation. Pit-forming osteoclasts possess round actin rings. In this study we show that trail-forming osteoclasts have crescent-shaped actin rings and provide a model that describes the detailed mechanism. To generate a trail, the actin ring of the resorption organelle attaches with one side outside the existing trail margin. The other side of the ring attaches to the wall inside the trail, thus sealing that narrow part to be resorbed next (3–21 lm). This 3D configuration allows vertical resorption layer-by-layer from the surface to a depth in combination with horizontal cell movement. Thus, trails are not just traces of a horizontal translation of osteoclasts during resorption. Additionally, we compared osteoclastic resorption on bone and dentin since the latter is the most frequently used in vitro model and data are extrapolated to bone. Histomorphometric analyses revealed a material-dependent effect reflected by an 11-fold higher resorption area and a sevenfold higher number of pits per square centimeter on dentin compared to bone. An important material-independent aspect was reflected by comparable mean pit area (μm²) and podosome patterns. Hence, dentin promotes the generation of resorbing osteoclasts, but once resorption has started, it proceeds independently of material properties. Thus, dentin is a suitable model substrate for data acquisition as long as osteoclast generation is not part of the analyses.

Morphological effects of MMPs inhibitors on the dentin bonding

PubMed Central

Li, He; Li, Tianbo; Li, Xiuying; Zhang, Zhimin; Li, Penglian; Li, Zhenling

2015-01-01

Matrix metalloproteinases (MMPs) have been studied extensively, and MMP inhibitors have been used as dental pretreatment agents prior to dentin bonding because they reduce collagen fiber degradation and improve bonding strength. However, morphologic characteristics of the collagen network after etching and of the post-adhesive dentin hybrid layers (DHL) after MMP inhibitors pretreatment have not been evaluated. Thus, we investigated demineralized dentin pretreated with chlorhexidine (CHX) and minocycline (MI) in an etch- and -rinse adhesive system with field emission scanning electron microscopy (FESEM) and immuno-gold labeling markers to observe the collagen network and DHL. FESEM revealed after CHX and MI, a demineralized dentin surface and improved collagen network formation, reduced collagen degradation, and distinct gold-labeling signals. Applying adhesive after either MMP inhibitor created a better dentin interface as evidenced by immuno-gold staining, better adhesive penetration, and higher DHL quality. With microtensile bond strength tests (µTBS) we estimated bonding strength using µTBS data. Immediate µTBS was enhanced with MMP inhibitor application to the bonding surface, and the CHX group was significantly different than non-treated etched surfaces, but no significant change was detected in the MI group. Surface micromorphology of the fractured dentin resin restoration showed that the CHX group had a better resin and dentin tube combination. Both MMP inhibitors created uniform resin coverage. Thus, morphologic results and µTBS data suggest that CHX and MI can inhibit MMP activity, improve immediate bonding strength, and enhance dentin bonding stability with an etch- and -rinse adhesive system. PMID:26379873

Enhanced bioactive properties of BiodentineTM modified with bioactive glass nanoparticles.

PubMed

Corral Nuñez, Camila; Covarrubias, Cristian; Fernandez, Eduardo; Oliveira, Osmir Batista de

2017-01-01

To prepare nanocomposite cements based on the incorporation of bioactive glass nanoparticles (nBGs) into BiodentineTM (BD, Septodent, Saint-Maur-des-Fosses Cedex, France) and to assess their bioactive properties. nBGs were synthesised by the sol-gel method. BD nanocomposites (nBG/BD) were prepared with 1 and 2% nBGs by weight; unmodified BD and GC Fuji IX (GIC, GC Corporation, Tokyo, Japan) were used as references. The in vitro ability of the materials to induce apatite formation was assessed in SBF by X-ray diffraction (XRD), attenuated total reflectance with Fourier transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis. BD and nBG/BD were also applied to dentine discs for seven days; the morphology and elemental composition of the dentine-cement interface were analysed using SEM-EDX. One and two percent nBG/BD composites accelerated apatite formation on the disc surface after short-term immersion in SBF. Apatite was detected on the nBG/BD nanocomposites after three days, compared with seven days for unmodified BD. No apatite formation was detected on the GIC surface. nBG/BD formed a wider interfacial area with dentine than BD, showing blockage of dentine tubules and Si incorporation, suggesting intratubular precipitation. The incorporation of nBGs into BD improves its in vitro bioactivity, accelerating the formation of a crystalline apatite layer on its surface after immersion in SBF. Compared with unmodified BD, nBG/BD showed a wider interfacial area with greater Si incorporation and intratubular precipitation of deposits when immersed in SBF.

Dentin abnormalities in cheek teeth of wild red deer and roe deer from a fluoride-polluted area in Central Europe.

PubMed

Richter, Heiko; Kierdorf, Uwe; Richards, Alan; Kierdorf, Horst

2010-04-20

This study analyses the severity and distribution of mineralization defects in the dentin of red and roe deer teeth (mandibular fourth premolars, first and third molars) obtained from individuals that had lived in a fluoride-polluted area along the Czech-German border. Mineralization defects presented as hypomineralized or interglobular dentin. In the P(4)s and M(3)s the entire dentin exhibited areas of defective mineralization, whereas in the M(1)s only the central and inner dentin portions were affected. This suggests that the early periods of dentin formation in the first molar, occurring during the late fetal and early postnatal (milk-feeding) periods of life, are protected against exposure to excess fluoride levels. Our findings are consistent with the hypothesis that certain protective mechanisms (partial placental diffusion barrier and blood-milk barrier to fluoride, clearance of fluoride from plasma by the rapidly growing skeleton) operate during these ontogenetic periods. Studying fluoride-induced dentin abnormalities in addition to enamel fluorosis broadens the time window during which fluoride effects on the developing dental hard tissues can be recorded. Including dentin in the analysis of dental fluorosis allows a more detailed reconstruction of lifetime fluoride exposure than would be possible by studying enamel fluorosis only, thereby adding to the significance of free-ranging deer as bioindicators of fluoride pollution. Copyright 2010 Elsevier GmbH. All rights reserved.

Synthesis of Calcium Phosphate Composite Organogels by Using Emulsion Method for Dentine Occlusion Materials

NASA Astrophysics Data System (ADS)

Nopteeranupharp, C.; Akkarachaneeyakorn, K.; Songsasaen, A.

2018-03-01

Dentinal hypersensitivity (DH) is one of the most human’s problems caused by the erosion of enamel. There are many methods and materials to solve this problem. Calcium phosphate is an excellent alternative for curing this symptom because of its osteoconductivity, and biocompatibility properties. The low-cost and low-toxicity calcium phosphate nanogel was fabricated by using emulsion method and characterized by using TEM, EDX, and DLS techniques. The results showed that P123 (poly (ethylene oxide)19-block-Poly (propylene oxide)69-block-poly (ethylene oxide)19) has played a major role as template and gel formation, SDS was used as a surfactant to form water-in-oil emulsion nanodroplets with circle-like shape. Moreover, the ability of synthesised organogel to occlude the exposed dentine tubules was tested on the model of human’s dentine slices. The results showed that calcium phosphate composite organogel can be efficiently occluded on dentine slice, characterized by SEM technique, after 1 day.

Antibacterial Properties Associated with Chitosan Nanoparticle Treatment on Root Dentin and 2 Types of Endodontic Sealers.

PubMed

Del Carpio-Perochena, Aldo; Kishen, Anil; Shrestha, Annie; Bramante, Clovis Monteiro

2015-08-01

The aim of this study was to evaluate the efficacy of carboxymethyl chitosan (CMCS) and chitosan nanoparticles (CNps) to inactivate bacteria and prevent biofilm formation at sealer-dentin interfaces. The study was divided into 3 stages: first stage, the experiment was conducted to analyze the antibacterial properties of CMCS in different formulations against biofilms; second stage, direct-contact and membrane-restricted methods were used to evaluate the antibacterial properties of an epoxy resin (ThermaSeal Plus; Dentsply Tulsa Dental, Tulsa, OK) and calcium silicate (MTA Fillapex; Angelus SA, Londrina, PR, Brazil) based-sealers with or without CNps; and third stage, biofilm formation at the sealer dentin interfaces of root dentin treated with CMCS and filled with gutta-percha and CNp incorporated sealer were analyzed after 1- and 4-week aging periods. The samples were treated and filled as follows: (1) distilled water: unaltered sealer (control group), (2) CMCS: sealer+CNps (CMCS group), and (3) CMCS/rose bengal: sealer+CNps (CMCS/RB group). Enterococcus faecalis was used to infect all the samples. Microbiological and microscopic analyses were used to assess the antibacterial characteristics. CMCS-based treatments effectively killed bacteria adherent on root dentin (P < .05). The addition of CNps to ThermaSeal enhanced its antibacterial ability by direct-contact and membrane-restricted tests (P < .05). The CNp incorporation significantly increased the antibacterial efficacy of root canal sealers even after a 4-week aging time (P < .05). This study highlighted the ability of CMCS to disinfect root canal dentin and inhibit bacterial adhesion. CNps in root canal sealers are capable of maintaining their antibacterial activity even after prolonged aging. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

The Effect of Canal Preparation with Four Different Rotary Systems on Formation of Dentinal Cracks: An In Vitro Evaluation.

PubMed

Khoshbin, Elham; Donyavi, Zakiyeh; Abbasi Atibeh, Erfan; Roshanaei, Ghodratollah; Amani, Faranak

2018-01-01

Endodontic rotary systems may result in dentinal cracks. They may propagate to vertical root fracture that compromises the outcome of endodontic treatment. This study aimed to compare Neolix and Reciproc (single-file systems), Mtwo and ProTaper (conventional rotary systems) in terms of dentinal crack formation in root canal walls. This in vitro study was conducted on 110 extracted human single-rooted teeth. The teeth were randomly divided into four experimental groups ( n =25) for root canal preparation with Neolix, Reciproc, Mtwo and ProTaper systems and two control groups ( n =5). The first control group underwent root canal instrumentation with hand files while the second control group received no preparation and was only irrigated. After instrumentation, root canals were horizontally sectioned at 3, 6 and 9 mm from the apex and inspected under a stereomicroscope under 12× magnification for detection of cracks. The data were analyzed using Chi-square, GEE test and Bonferroni tests ( P <0.05). No crack was found in the control groups. All rotary systems caused dentinal cracks. ProTaper, Reciproc, Mtwo and Neolix caused cracks in 92%, 80%, 68% and 48% of samples. ProTaper caused significantly more cracks than Neolix and Mtwo ( P <0.05). No significant differences were noted between other groups ( P >0.05). All rotary systems cause dentinal cracks and it is significantly different in apical, middle and coronal third of the root. Neolix appears to be a suitable alternative to other rotary systems since use of this single-file system saves time and cost and minimizes trauma to dentinal walls.

The Effect of Canal Preparation with Four Different Rotary Systems on Formation of Dentinal Cracks: An In Vitro Evaluation

PubMed Central

Khoshbin, Elham; Donyavi, Zakiyeh; Abbasi Atibeh, Erfan; Roshanaei, Ghodratollah; Amani, Faranak

2018-01-01

Introduction: Endodontic rotary systems may result in dentinal cracks. They may propagate to vertical root fracture that compromises the outcome of endodontic treatment. This study aimed to compare Neolix and Reciproc (single-file systems), Mtwo and ProTaper (conventional rotary systems) in terms of dentinal crack formation in root canal walls. Methods and Materials: This in vitro study was conducted on 110 extracted human single-rooted teeth. The teeth were randomly divided into four experimental groups (n=25) for root canal preparation with Neolix, Reciproc, Mtwo and ProTaper systems and two control groups (n=5). The first control group underwent root canal instrumentation with hand files while the second control group received no preparation and was only irrigated. After instrumentation, root canals were horizontally sectioned at 3, 6 and 9 mm from the apex and inspected under a stereomicroscope under 12× magnification for detection of cracks. The data were analyzed using Chi-square, GEE test and Bonferroni tests (P<0.05). Results: No crack was found in the control groups. All rotary systems caused dentinal cracks. ProTaper, Reciproc, Mtwo and Neolix caused cracks in 92%, 80%, 68% and 48% of samples. ProTaper caused significantly more cracks than Neolix and Mtwo (P<0.05). No significant differences were noted between other groups (P>0.05). Conclusion: All rotary systems cause dentinal cracks and it is significantly different in apical, middle and coronal third of the root. Neolix appears to be a suitable alternative to other rotary systems since use of this single-file system saves time and cost and minimizes trauma to dentinal walls. PMID:29707009

Transcriptional Repression of the Dspp Gene Leads to Dentinogenesis Imperfecta Phenotype in Col1a1-Trps1 Transgenic Mice

PubMed Central

Napierala, Dobrawa; Sun, Yao; Maciejewska, Izabela; Bertin, Terry K; Dawson, Brian; D'Souza, Rena; Qin, Chunlin; Lee, Brendan

2012-01-01

Dentinogenesis imperfecta (DGI) is a hereditary defect of dentin, a calcified tissue that is the most abundant component of teeth. Most commonly, DGI is manifested as a part of osteogenesis imperfecta (OI) or the phenotype is restricted to dental findings only. In the latter case, DGI is caused by mutations in the DSPP gene, which codes for dentin sialoprotein (DSP) and dentin phosphoprotein (DPP). Although these two proteins together constitute the majority of noncollagenous proteins of the dentin, little is known about their transcriptional regulation. Here we demonstrate that mice overexpressing the Trps1 transcription factor (Col1a1-Trps1 mice) in dentin-producing cells, odontoblasts, present with severe defects of dentin formation that resemble DGI. Combined micro–computed tomography (µCT) and histological analyses revealed tooth fragility due to severe hypomineralization of dentin and a diminished dentin layer with irregular mineralization in Col1a1-Trps1 mice. Biochemical analyses of noncollagenous dentin matrix proteins demonstrated decreased levels of both DSP and DPP proteins in Col1a1-Trps1 mice. On the molecular level, we demonstrated that sustained high levels of Trps1 in odontoblasts lead to dramatic decrease of Dspp expression as a result of direct inhibition of the Dspp promoter by Trps1. During tooth development Trps1 is highly expressed in preodontoblasts, but in mature odontoblasts secreting matrix its expression significantly decreases, which suggests a Trps1 role in odontoblast development. In these studies we identified Trps1 as a potent inhibitor of Dspp expression and the subsequent mineralization of dentin. Thus, we provide novel insights into mechanisms of transcriptional dysregulation that leads to DGI. © 2012 American Society for Bone and Mineral Research. PMID:22508542

Fourier transform infrared photoacoustic spectroscopy study of physicochemical interaction between human dentin and etch-&-rinse adhesives in a simulated moist bond technique.

PubMed

Ubaldini, Adriana L M; Baesso, Mauro L; Sehn, Elizandra; Sato, Francielle; Benetti, Ana R; Pascotto, Renata C

2012-06-01

The purpose of this study was to provide the physicochemical interactions at the interfaces between two commercial etch-&-rinse adhesives and human dentin in a simulated moist bond technique. Six dentin specimens were divided into two groups (n=3) according to the use of two different adhesive systems: (a) 2-hydroxyethylmethacrylate (HEMA) and 4-methacryloxyethyl trimellitate anhydrate (4-META), and (b) HEMA. The Fourier transform infrared photoacoustic spectroscopy was performed before and after dentin treatment with 37% phosphoric acid, with adhesive systems and also for the adhesive systems alone. Acid-conditioning resulted in a decalcification pattern. Adhesive treated spectra subtraction suggested the occurrence of chemical bonding to dentin expressed through modifications of the OH stretching peak (3340 cm(-1)) and symmetric CH stretching (2900 cm(-1)) for both adhesives spectra; a decrease of orthophosphate absorption band (1040 to 970 cm(-1)) for adhesive A and a better resolved complex band formation (1270 to 970 cm(-1)) for adhesive B were observed. These results suggested the occurrence of chemical bonding between sound human dentin and etch-&-rinse adhesives through a clinical typical condition.

Dentin extracellular matrix (ECM) proteins: comparison to bone ECM and contribution to dynamics of dentinogenesis.

PubMed

Butler, William T; Brunn, Jan C; Qin, Chunlin

2003-01-01

Dentinogenesis involves the initial odontoblastic synthesis of a collagen-rich extracellular matrix (ECM) and predentin that is converted to dentin when the collagen fibrils become mineralized. Since the width of predentin is rather uniform, we postulate that extracellular events regulate dentinogenesis. Similarly, osteogenesis involves an initial unmineralized osteoid that is mineralized and converted to bone. To gain insights into these two processes, we compared ECM proteins in bone with those in dentin, focusing upon the sialic acid (SA)-rich proteins. We observed qualitative similarities between the SA-rich proteins, but distinct differences in the amounts of osteopontin (OPN) and dentin sialoprotein (DSP). OPN, a predominant protein in bone, was found in much smaller amounts in dentin. Conversely, DSP was abundant in dentin ECM, but found sparingly in bone. Molecular cloning experiments indicate that coding sequences for DSP and dentin phosphoprotein (DPP) are found on the same mRNA. We believe that the initial form of the precursor protein DSPP is inactive in influencing the mineralization process and that it must be activated by cleavage of peptide bonds in conserved regions. Thus, unknown proteinases would act on DSPP, possibly at the mineralization front, and liberate active DPP, which plays an initiation and regulatory role in the formation of apatite crystals. This post-translational processing reaction would represent an important control point in dentinogenesis. Recently, we identified uncleaved DSPP in dentin extracts, which should allow us to test portions of our hypothesis.

Enhanced bioactive properties of BiodentineTM modified with bioactive glass nanoparticles

PubMed Central

CORRAL NUÑEZ, Camila; COVARRUBIAS, Cristian; FERNANDEZ, Eduardo; de OLIVEIRA, Osmir Batista

2017-01-01

Abstract Objective To prepare nanocomposite cements based on the incorporation of bioactive glass nanoparticles (nBGs) into BiodentineTM (BD, Septodent, Saint-Maur-des-Fosses Cedex, France) and to assess their bioactive properties. Material and Methods nBGs were synthesised by the sol-gel method. BD nanocomposites (nBG/BD) were prepared with 1 and 2% nBGs by weight; unmodified BD and GC Fuji IX (GIC, GC Corporation, Tokyo, Japan) were used as references. The in vitro ability of the materials to induce apatite formation was assessed in SBF by X-ray diffraction (XRD), attenuated total reflectance with Fourier transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis. BD and nBG/BD were also applied to dentine discs for seven days; the morphology and elemental composition of the dentine-cement interface were analysed using SEM-EDX. Results One and two percent nBG/BD composites accelerated apatite formation on the disc surface after short-term immersion in SBF. Apatite was detected on the nBG/BD nanocomposites after three days, compared with seven days for unmodified BD. No apatite formation was detected on the GIC surface. nBG/BD formed a wider interfacial area with dentine than BD, showing blockage of dentine tubules and Si incorporation, suggesting intratubular precipitation. Conclusions The incorporation of nBGs into BD improves its in vitro bioactivity, accelerating the formation of a crystalline apatite layer on its surface after immersion in SBF. Compared with unmodified BD, nBG/BD showed a wider interfacial area with greater Si incorporation and intratubular precipitation of deposits when immersed in SBF. PMID:28403358

Periodontal ligament stem/progenitor cells with protein-releasing scaffolds for cementum formation and integration on dentin surface.

PubMed

Cho, Hankyu; Tarafder, Solaiman; Fogge, Michael; Kao, Kristy; Lee, Chang H

2016-11-01

Purpose/Aim: Cementogenesis is a critical step in periodontal tissue regeneration given the essential role of cementum in anchoring teeth to the alveolar bone. This study is designed to achieve integrated cementum formation on the root surfaces of human teeth using growth factor-releasing scaffolds with periodontal ligament stem/progenitor cells (PDLSCs). Human PDLSCs were sorted by CD146 expression, and characterized using CFU-F assay and induced multi-lineage differentiation. Polycaprolactone scaffolds were fabricated using 3D printing, embedded with poly(lactic-co-glycolic acids) (PLGA) microspheres encapsulating connective tissue growth factor (CTGF), bone morphogenetic protein-2 (BMP-2), or bone morphogenetic protein-7 (BMP-7). After removing cementum on human tooth roots, PDLSC-seeded scaffolds were placed on the exposed dentin surface. After 6-week culture with cementogenic/osteogenic medium, cementum formation and integration were evaluated by histomorphometric analysis, immunofluorescence, and qRT-PCR. Periodontal ligament (PDL) cells sorted by CD146 and single-cell clones show a superior clonogenecity and multipotency as compared with heterogeneous populations. After 6 weeks, all the growth factor-delivered groups showed resurfacing of dentin with a newly formed cementum-like layer as compared with control. BMP-2 and BMP-7 showed de novo formation of tissue layers significantly thicker than all the other groups, whereas CTGF and BMP-7 resulted in significantly improved integration on the dentin surface. The de novo mineralized tissue layer seen in BMP-7-treated samples expressed cementum matrix protein 1 (CEMP1). Consistently, BMP-7 showed a significant increase in CEMP1 mRNA expression. Our findings represent important progress in stem cell-based cementum regeneration as an essential part of periodontium regeneration.

Modeling micromechanical measurements of depth-varying properties with scanning acoustic microscopy

NASA Astrophysics Data System (ADS)

Marangos, Orestes; Misra, Anil

2018-02-01

Scanning acoustic microscopy (SAM) has been applied to measure the near-surface elastic properties of materials. For many substrates, the near-surface property is not constant but varies with depth. In this paper, we aim to interpret the SAM data from such substrates by modeling the interaction of the focused ultrasonic field with a substrate having a near-surface graded layer. The focused ultrasonic field solutions were represented as spherical harmonic expansions while the substrate solutions were represented as plane wave expansions. The bridging of the two solutions was achieved through the decomposition of the ultrasonic pressure fields in their angular spectra. Parametric studies were performed, which showed that near-surface graded layers exhibit distinctive frequency dependence of their reflectance functions. This behavior is characteristic to the material property gradation profile as well as the extent of the property gradation. The developed model was used to explain the frequency-dependent reflection coefficients measured from an acid-etched dentin substrate. Based on the model calculations, the elastic property variations of the acid-etched dentin near-surface indicate that the topmost part of the etched layer is very soft (3-6 GPa) and transitions to the native dentin through a depth of 27 and 36 microns.

Liquid nitrogen-treated autogenous dentin as bone substitute: an experimental study in a rabbit model.

PubMed

Atiya, Basim K; Shanmuhasuntharam, Palasuntharam; Huat, Siar; Abdulrazzak, Shurooq; Oon, Ha

2014-01-01

Different forms of dentin, including untreated, undemineralized, demineralized, boiled, or mixed with other materials, have been evaluated for efficacy as bone substitutes. However, the effects of application of liquid nitrogen-treated dentin for bone grafting remain unknown. The objective of this study was to chronologically evaluate bone healing following grafting with liquid nitrogen-treated dentin in a rabbit model. Autogenous dentin treated with liquid nitrogen at -196°C for 20 minutes was used. In 16 New Zealand White rabbits, a bone defect (5 mm in diameter) was created in each femur and randomly grafted with either autogenous dentin (experimental group) or autogenous bone grafts (positive control). In another four rabbits (negative control), a similar defect in each femur was left empty. The rabbits were sacrificed at 2, 4, 8, and 12 weeks. Explants of grafted sites were harvested for histologic and histomorphometric analysis. At 2 and 4 weeks in both the experimental and positive control groups, accelerated formation of new bone was observed, which was undergoing remodeling at 8 and 12 weeks. The mean new bone score was higher in the experimental than in the negative control groups, but this was not statistically significant. The present results demonstrated that liquid nitrogen-treated autogenous dentin has both osteoconductive and osteoinductive properties and therefore has potential as a bone substitute.

Residual Microstrain in Root Dentin after Canal Instrumentation Measured with Digital Moiré Interferometry.

PubMed

Lim, Helena; Li, Fang-Chi; Friedman, Shimon; Kishen, Anil

2016-09-01

Residual microstrain influences the resistance to crack propagation in a biomaterial. This study evaluated the residual microstrain and microdefects formed in dentin after canal instrumentation in teeth maintained in hydrated and nonhydrated environments. Canals of 18 extracted human premolars with single-root canals were instrumented in accordance with 3 groups: the ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) group: ProTaper Universal (S1, S2, F1, and F2) used in rotation, the WaveOne Primary (Dentsply Maillefer) group: the WaveOne (Primary) used in reciprocal motion, and the control group: hand files. Half the specimens (3/group) were maintained in deionized water (hydrated) and half in ambient relative humidity conditions (22°C, 55% RH) for 72 hours (nonhydrated). Customized high-sensitivity digital moiré interferometry was used to qualitatively evaluate pre- and postinstrumentation dentinal microstrain. Subsequently, specimens were examined for dentinal microdefects with micro-computed tomographic imaging and polarized light microscopy. Digital moiré interferometry showed only minor changes in postinstrumentation microstrain in hydrated dentin in all groups, suggestive of a stress relaxation behavior. Nonhydrated dentin in all groups showed localized concentration of postinstrumentation microstrain, which appeared higher in the WaveOne group than in the other groups. No dentinal microdefects were detected by micro-computed tomographic imaging and polarized light microscopy in hydrated and nonhydrated specimens in all groups. This study suggested that the biomechanical response of root dentin to instrumentation was influenced by hydration. Reciprocating, rotary, and hand instrumentation of well-hydrated roots did not cause an increase in residual microstrain or the formation of microdefects in root dentin. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Incidence of Dentinal Crack after Root Canal Preparation by ProTaper Universal, Neolix and SafeSider Systems

PubMed Central

Harandi, Azadeh; Mirzaeerad, Sina; Mehrabani, Mahgol; Mahmoudi, Elham; Bijani, Ali

2017-01-01

Introduction: This study aimed to compare the incidence of dentinal crack formation by instrumentation with ProTaper Universal system (rotary, multi-file system), SafeSider (reciprocation movement, multi-file system) and Neolix (rotary, single-file system). Methods and Materials: In this in vitro study, 60 freshly extracted mandibular first molars were randomly divided into three experimental groups (n=15) and a control group containing unprepared teeth (n=15). Instrumentation in different groups was accomplished using either ProTaper, Neolix or SafeSider systems up to 25/0.08. The teeth were then sectioned at 3, 6 and 9 mm from the apex, and observed under a stereomicroscope for presence of dentinal cracks. Data were analyzed with Chi square test, Fisher’s exact test and Bonferroni correction. Results: Micro cracks were seen in all experimental groups (13.3% in ProTaper, 26.7% in SafeSider and 40% in Neolix). There was a significant difference between Neolix and the control groups in microcrack formation (P=0.042). Micro cracks mainly occurred in the coronal section (9 mm). No microcrack occurred in the control group. Conclusion: Neolix rotary single-file system caused more dentinal cracks compared to the unprepared roots. All the instrumentation systems increased the number of micro cracks compared to unprepared teeth. PMID:29225637

Ectopic expression of dentin sialoprotein during amelogenesis hardens bulk enamel.

PubMed

White, Shane N; Paine, Michael L; Ngan, Amanda Y W; Miklus, Vetea G; Luo, Wen; Wang, HongJun; Snead, Malcolm L

2007-02-23

Dentin sialophosphpoprotein (Dspp) is transiently expressed in the early stage of secretory ameloblasts. The secretion of ameloblast-derived Dspp is short-lived, correlates to the establishment of the dentinoenamel junction (DEJ), and is consistent with Dspp having a role in producing the specialized first-formed harder enamel adjacent to the DEJ. Crack diffusion by branching and dissipation within this specialized first-formed enamel close to the DEJ prevents catastrophic interfacial damage and tooth failure. Once Dspp is secreted, it is subjected to proteolytic cleavage that results in two distinct proteins referred to as dentin sialoprotein (Dsp) and dentin phosphoprotein (Dpp). The purpose of this study was to investigate the biological and mechanical contribution of Dsp and Dpp to enamel formation. Transgenic mice were engineered to overexpress either Dsp or Dpp in their enamel organs. The mechanical properties (hardness and toughness) of the mature enamel of transgenic mice were compared with genetically matched and age-matched nontransgenic animals. Dsp and Dpp contributions to enamel formation greatly differed. The inclusion of Dsp in bulk enamel significantly and uniformly increased enamel hardness (20%), whereas the inclusion of Dpp weakened the bulk enamel. Thus, Dsp appears to make a unique contribution to the physical properties of the DEJ. Dsp transgenic animals have been engineered with superior enamel mechanical properties.

MEPE Localization in the Craniofacial Complex and Function in Tooth Dentin Formation.

PubMed

Gullard, Angela; Gluhak-Heinrich, Jelica; Papagerakis, Silvana; Sohn, Philip; Unterbrink, Aaron; Chen, Shuo; MacDougall, Mary

2016-04-01

Matrix extracellular phosphoglycoprotein (MEPE) is an extracellular matrix protein found in dental and skeletal tissues. Although information regarding the role of MEPE in bone and disorders of phosphate metabolism is emerging, the role of MEPE in dental tissues remains unclear. We performed RNA in situ hybridization and immunohistochemistry analyses to delineate the expression pattern of MEPE during embryonic and postnatal development in craniofacial mineralizing tissues. Mepe RNA expression was seen within teeth from cap through root formation in association with odontoblasts and cellular cementoblasts. More intense expression was seen in the alveolar bone within the osteoblasts and osteocytes. MEPE immunohistochemistry showed biphasic dentin staining in incisors and more intense staining in alveolar bone matrix and in forming cartilage. Analysis of Mepe null mouse molars showed overall mineralized tooth volume and density of enamel and dentin comparable with that of wild-type samples. However, Mepe(-/-) molars exhibited increased thickness of predentin, dentin, and enamel over controls and decreased gene expression of Enam, Bsp, Dmp1, Dspp, and Opnby RT-PCR. In vitro Mepe overexpression in odontoblasts led to significant reductions in Dspp reporter activity. These data suggest MEPE may be instrumental in craniofacial and dental matrix maturation, potentially functioning in the maintenance of non-mineralized matrix. © 2016 The Histochemical Society.

Role of LIGHT in the pathogenesis of joint destruction in rheumatoid arthritis

PubMed Central

Sabokbar, Afsie; Afrough, Sara; Mahoney, David J; Uchihara, Yoshinobu; Swales, Catherine; Athanasou, Nicholas A

2017-01-01

AIM To characterise the role of substitutes for receptor-activator nuclear factor kappa-B ligand (RANKL) in rheumatoid arthritis (RA) joint destruction. METHODS Synovial fluid (SF) macrophages isolated from the knee joint of RA patients were incubated with 25 ng/mL macrophage-colony stimulating factor (M-CSF) and 50 ng/mL LIGHT (lymphotoxin-like, exhibits inducible expression and competes with herpes simplex virus glycoprotein D for herpes virus entry mediator, a receptor expressed by T lymphocytes) in the presence and absence of 25 ng/mL RANKL and 100 ng/mL osteoprotegerin (OPG) on glass coverslips and dentine slices. Osteoclastogenesis was assessed by the formation of multinucleated cells (MNCs) expressing tartrate-resistant acid phosphatase (TRAP) on coverslips and the extent of lacunar resorption pit formation on dentine slices. The concentration of LIGHT in RA and osteoarthritis (OA) synovial fluid was measured by an enzyme-linked immunosorbent assay (ELISA) and the expression of LIGHT in RA and OA synovium was determined by immunohistochemistry using an indirect immunoperoxidase technique. RESULTS In cultures of RA SF macrophages treated with LIGHT and M-CSF, there was significant formation of TRAP + MNCs on coverslips and extensive lacunar resorption pit formation on dentine slices. SF-macrophage-osteoclast differentiation was not inhibited by the addition of OPG, a decoy receptor for RANKL. Resorption pits were smaller and less confluent than in RANKL-treated cultures but the overall percentage area of the dentine slice resorbed was comparable in LIGHT- and RANKL-treated cultures. LIGHT significantly stimulated RANKL-induced lacunar resorption compared with RA SF macrophages treated with either RANKL or LIGHT alone. LIGHT was strongly expressed by synovial lining cells, subintimal macrophages and endothelial cells in RA synovium and the concentration of LIGHT was much higher in RA compared with OA SF. CONCLUSION LIGHT is highly expressed in RA synovium and SF, stimulates RANKL-independent/dependent osteoclastogenesis from SF macrophages and may contribute to marginal erosion formation. PMID:28589079

Effects of recombinant dentin sialoprotein in dental pulp cells.

PubMed

Lee, S-Y; Kim, S-Y; Park, S-H; Kim, J-J; Jang, J-H; Kim, E-C

2012-04-01

Dentin sialophosphoprotein (DSPP) is critical for dentin mineralization. However, the function of dentin sialoprotein (DSP), the cleaved product of DSPP, remains unclear. This study aimed to investigate the signal transduction pathways and effects of recombinant human DSP (rh-DSP) on proliferation, migration, and odontoblastic differentiation in human dental pulp cells (HDPCs). The exogenous addition of rh-DSP enhanced the proliferation and migration of HDPCs in dose- and time-dependent manners. rh-DSP markedly increased ALP activity, calcium nodule formation, and levels of odontoblastic marker mRNA. rh-DSP increased BMP-2 expression and Smad1/5/8 phosphorylation, which was blocked by the BMP antagonist, noggin. Furthermore, rh-DSP phosphorylated extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), Akt, and IκB-α, and induced the nuclear translocation of the NF-κB p65 subunit. Analysis of these data demonstrates a novel signaling function of rh-DSP for the promotion of growth, migration, and differentiation in HDPCS via the BMP/Smad, JNK, ERK, MAPK, and NF-κB signaling pathways, suggesting that rh-DSP may have therapeutic utility in dentin regeneration or dental pulp tissue engineering.

Dentinogenic Specificity in the Preclinical Evaluation of Vital Pulp Treatment Strategies: A Critical Review.

PubMed

Tziafas, Dimitrios; Kodonas, Konstantinos

2015-11-27

Reviews on the clinical performance of vital pulp treatment strategies and capping materials repeatedly showed an insufficient grade of evidence concerning their therapeutic validity. The biological mechanisms underlying the regenerative potential of pulp-dentin complex have attracted much attention during the last two decades, since new pulp treatment modalities have been designed and tested at the preclinical level. It has been recognized that evaluation should be based on the specific ability of therapeutic interventions to signal recruitment and differentiation of odontoblast-like cells forming a matrix in a predentin-like pattern, rather than uncontrolled hard tissue deposition in a scar-like form. The aim of the present article was to critically review data from histological experimental studies on pulp capping, published during the last 7 decades. A comprehensive literature search covering the period from 1949 to 2015 was done using the Medline/Pubmed database. Inclusion of a study was dependent on having sufficient data regarding the type of capping material used and the unit of observation (human permanent tooth in vivo or animal permanent dentition; primary teeth were excluded). The post-operatively deposited matrix was categorized into three types: unspecified, osteotypic, or dentin-like matrix. One hundred fifty-two studies were included in the final evaluation. Data from the present systematic review have shown that only 30.2% of the 152 experimental histological pulp capping studies described the heterogenic nature of the hard tissue bridge formation, including osteotypic and tubular mineralized tissue. Structural characteristics of the new matrix and the associated formative cells were not provided by the remaining 106 studies. Analysis showed that more careful preclinical evaluation with emphasis on the evidence regarding the dentinogenic specificity of pulp therapies is required. It seems that selection of appropriate vital pulp treatment strategies and pulp capping materials would be further facilitated in terms of their therapeutic validity if international consensus could be reached on a select number of mandatory criteria for tissue-specific dentinogenic events.

Dentinogenic Specificity in the Preclinical Evaluation of Vital Pulp Treatment Strategies: A Critical Review

PubMed Central

Tziafas, Dimitrios; Kodonas, Konstantinos

2015-01-01

Reviews on the clinical performance of vital pulp treatment strategies and capping materials repeatedly showed an insufficient grade of evidence concerning their therapeutic validity. The biological mechanisms underlying the regenerative potential of pulp-dentin complex have attracted much attention during the last two decades, since new pulp treatment modalities have been designed and tested at the preclinical level. It has been recognized that evaluation should be based on the specific ability of therapeutic interventions to signal recruitment and differentiation of odontoblast-like cells forming a matrix in a predentin-like pattern, rather than uncontrolled hard tissue deposition in a scar-like form. The aim of the present article was to critically review data from histological experimental studies on pulp capping, published during the last 7 decades. A comprehensive literature search covering the period from 1949 to 2015 was done using the Medline/Pubmed database. Inclusion of a study was dependent on having sufficient data regarding the type of capping material used and the unit of observation (human permanent tooth in vivo or animal permanent dentition; primary teeth were excluded). The post-operatively deposited matrix was categorized into three types: unspecified, osteotypic, or dentin-like matrix. One hundred fifty-two studies were included in the final evaluation. Data from the present systematic review have shown that only 30.2% of the 152 experimental histological pulp capping studies described the heterogenic nature of the hard tissue bridge formation, including osteotypic and tubular mineralized tissue. Structural characteristics of the new matrix and the associated formative cells were not provided by the remaining 106 studies. Analysis showed that more careful preclinical evaluation with emphasis on the evidence regarding the dentinogenic specificity of pulp therapies is required. It seems that selection of appropriate vital pulp treatment strategies and pulp capping materials would be further facilitated in terms of their therapeutic validity if international consensus could be reached on a select number of mandatory criteria for tissue-specific dentinogenic events. PMID:29567934

Bone Sialoproteins and Breast Cancer Detection

DTIC Science & Technology

2005-07-01

Fig. 8 shows (DSPP) gene within the critical dentinogenesis imperfecta type 11 and BSP with an intact RGD bridging MMP-2 to its cell-surface dentin...sialoprotein (BSP) and the pivotal transcriptional oebter Gasy seler I Freedma NcWe of BiselarMa.tMatix regulator of osteogenesis , Cbfal/Runx2, in malignant...potential the pathogenesis of dentinogenesis imperfecta type II. Genomics 1997; diagnostic biomarker for ovarian cancer. JAMA 2002;287:1671-9. 42:38-45

Zinc incorporation improves biological activity of beta-tricalcium silicate resin-based cement.

PubMed

Osorio, Raquel; Yamauti, Monica; Sauro, Salvatore; Watson, Tim F; Toledano, Manuel

2014-11-01

Matrix metalloproteinase (MMP) inhibition may improve endodontic treatment prognosis. The purpose of this study was to determine if zinc incorporation into experimental resin cements containing bioactive fillers may modulate MMP-mediated collagen degradation of dentin. Human dentin samples untreated and demineralized using 10% phosphoric acid or 0.5 mol/L EDTA were infiltrated with the following experimental resins: (1) unfilled resin, (2) resin with Bioglass 45S5 particles (OSspray, London, UK), (3) resin with beta-tricalcium silicate particles (βTCS), (4) resin with zinc-doped Bioglass 45S5, and (5) resin with zinc-doped βTCS particles. The specimens were stored in artificial saliva (for 24 hours, 1 week, and 4 weeks) and submitted to radioimmunoassay to quantify C-terminal telopeptide. Scanning electron microscopy analysis was also undertaken on dentin samples after 4 weeks of storage. Collagen degradation was prominent both in phosphoric acid and EDTA-treated dentin. Resin infiltration strongly reduced MMP activity in demineralized dentin. Resin containing Bioglass 45S5 particles exerted higher and stable protection of collagen. The presence of zinc in βTCS particles increases MMP inhibition. Different mineral precipitation was attained in dentin infiltrated with the resin cements containing bioactive fillers. MMP degradation of dentin collagen is strongly reduced after resin infiltration of dentin. Zinc incorporation in βTCS particles exerted an additional protection against MMP-mediated collagen degradation. However, it did not occur in resin containing Bioglass 45S5 particles, probably because of the formation of phosphate-zinc compounds. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Accelerated enamel mineralization in Dspp mutant mice

PubMed Central

Verdelis, Kostas; Szabo-Rogers, Heather L.; Xu, Yang; Chong, Rong; Kang, Ryan; Cusack, Brian J.; Jani, Priyam; Boskey, Adele L.; Qin, Chunlin; Beniash, Elia

2016-01-01

Dentin sialophosphoprotein (DSPP) is one of the major non-collagenous proteins present in dentin, cementum and alveolar bone; it is also transiently expressed by ameloblasts. In humans many mutations have been found in DSPP and are associated with two autosomal-dominant genetic diseases — dentinogenesis imperfecta II (DGI-II) and dentin dysplasia (DD). Both disorders result in the development of hypomineralized and mechanically compromised teeth. The erupted mature molars of Dspp–/– mice have a severe hypomineralized dentin phenotype. Since dentin and enamel formations are interdependent, we decided to investigate the process of enamel onset mineralization in young Dspp–/– animals. We focused our analysis on the constantly erupting mouse incisor, to capture all of the stages of odontogenesis in one tooth, and the unerupted first molars. Using high-resolution microCT, we revealed that the onset of enamel matrix deposition occurs closer to the cervical loop and both secretion and maturation of enamel are accelerated in Dspp–/– incisors compared to the Dspp+/– control. Importantly, these differences did not translate into major phenotypic differences in mature enamel in terms of the structural organization, mineral density or hardness. The only observable difference was the reduction in thickness of the outer enamel layer, while the total enamel thickness remained unchanged. We also observed a compromised dentin-enamel junction, leading to delamination between the dentin and enamel layers. The odontoblast processes were widened and lacked branching near the DEJ. Finally, for the first time we demonstrate expression of Dspp mRNA in secretory ameloblasts. In summary, our data show that DSPP is important for normal mineralization of both dentin and enamel. PMID:26780724

Efficacy of Modified Bioactive Glass for Dentin Remineralization and Obstruction of Dentinal Tubules.

PubMed

Saffarpour, Mahshid; Mohammadi, Maryam; Tahriri, Mohammadreza; Zakerzadeh, Azadeh

2017-07-01

This study assessed the efficacy of modified bioactive glass (MBG) for dentin remineralization and obstruction of dentinal tubules. Thirty-six dentin discs were made from 20 third molars and were stored in 12% lactic acid solution for two weeks to induce demineralization. The samples were divided into three groups (n=12): 1- BG, 2- BG modified with 5% strontium (Sr) and 3- BG modified with 10% Sr. After applying the BG, the samples were stored in artificial saliva for 7, 14 and 21 days. Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray (EDX) analysis were used to assess remineralization. Also, 6 dentin discs were divided into three groups of BG, BG modified with 5% Sr and BG modified with 10% Sr, to examine tubular occlusion. The discs were etched using 0.5M of EDTA for two minutes and were stored in artificial saliva for 7 days. Changes in dentin surface morphology were evaluated under SEM. Group 3 showed high rates of remineralization at days 7 and 14, although the rate decreased at day 21. Group 2 exhibited high rates of remineralization at days 7, 14 and 21. Dentinal tubules were partially occluded by BG and BG modified with 5% Sr, while they were almost completely obstructed after the use of BG modified with 10% Sr. Strontium increases remineralization. Addition of 10% Sr to BG enhances apatite formation; however, the apatite dissolves over time. Addition of 5% Sr to BG stabilizes the apatite lattice and increases the remineralization.

Clinical status of ten dentin adhesive systems.

PubMed

Van Meerbeek, B; Peumans, M; Verschueren, M; Gladys, S; Braem, M; Lambrechts, P; Vanherle, G

1994-11-01

Laboratory testing of dentin adhesive systems still requires corroboration by long-term clinical trials for their ultimate clinical effectiveness to be validated. The objective of this clinical investigation was to evaluate, retrospectively, the clinical effectiveness of earlier-investigated dentin adhesive systems (Scotchbond, Gluma, Clearfil New Bond, Scotchbond 2, Tenure, and Tripton), and to compare their clinical results with those obtained with four modern total-etch adhesive systems (Bayer exp. 1 and 2, Clearfil Liner Bond System, and Scotchbond Multi-Purpose). In total, 1177 Class V cervical lesions in the teeth of 346 patients were restored following two cavity designs: In Group A, enamel was neither beveled nor intentionally etched, as per ADA guidelines; in Group B, adjacent enamel was beveled and conditioned. Clinical retention rates definitely indicated the improved clinical efficacy of the newest dentin adhesives over the earlier systems. With regard to adhesion strategy, adhesive systems that removed the smear layer and concurrently demineralized the dentin surface layer performed clinically better than systems that modified the disorderly layer of smear debris without complete removal. Hybridization by resin interdiffusion into the exposed dentinal collagen layer, combined with attachment of resin tags into the opened dentin tubules, appeared to be essential for reliable dentin bonding but might be insufficient by itself. The additional formation of an elastic bonding area as a polymerization shrinkage absorber and the use of a microfine restorative composite apparently guaranteed an efficient clinical result. The perfect one-year retention recorded for Clearfil Liner Bond System and Scotchbond Multi-Purpose must be confirmed at later recalls.

Mechanisms Regulating the Degradation of Dentin Matrices by Endogenous Dentin Proteases and their Role in Dental Adhesion. A Review

PubMed Central

Sabatini, Camila; Pashley, David H.

2015-01-01

Purpose This systematic review provides an overview of the different mechanisms proposed to regulate the degradation of dentin matrices bye host-derived dentin proteases, particularly as it relates to their role in dental adhesion. Methods Significant developments have taken place over the last few years that have contributed to a better understanding of all the factors affecting the durability of adhesive resin restorations. The complexity of dentin-resin interfaces mandates a thorough understanding of all the mechanical, physical and biochemical aspects that play a role in the formation of hybrid layers. The ionic and hydrophilic nature of current dental adhesives yields permeable, unstable hybrid layers susceptible to water sorption, hydrolytic degradation and resin leaching. The hydrolytic activity of host-derived proteases also contributes to the degradation of the resin-dentin bonds. Preservation of the collagen matrix is critical to the improvement of resin-dentin bond durability. Approaches to regulate collagenolytic activity of dentin proteases have been the subject of extensive research in the last few years. A shift has occurred from the use of proteases inhibitors to the use of collagen cross-linking agents. Data provided by fifty-one studies published in peer-reviewed journals between January 1999 and December 2013 was compiled in this systematic review. Results Appraisal of the data provided by the studies included in the present review yielded a summary of the mechanisms which have already proven to be clinically successful and those which need further investigation before new clinical protocols can be adopted. PMID:25831604

Reconstructing temporal variation of fluoride uptake in eastern grey kangaroos (Macropus giganteus) from a high-fluoride area by analysis of fluoride distribution in dentine.

PubMed

Kierdorf, Horst; Rhede, Dieter; Death, Clare; Hufschmid, Jasmin; Kierdorf, Uwe

2016-04-01

Trace element profiling in the incrementally formed dentine of mammalian teeth can be applied to reconstruct temporal variation of incorporation of these elements into the tissue. Using an electron microprobe, this study analysed fluoride distribution in dentine of first and third mandibular molars of free-ranging eastern grey kangaroos inhabiting a high-fluoride area, to assess temporal variation in fluoride uptake of the animals. Fluoride content in the early-formed dentine of first molars was significantly lower than in the late-formed dentine of these teeth, and was also lower than in both, the early and the late-formed dentine of third molars. As early dentine formation in M1 takes place prior to weaning, this finding indicates a lower dentinal fluoride uptake during the pre-weaning compared to the post-weaning period. This is hypothetically attributed to the action of a partial barrier to fluoride transfer from blood to milk in lactating females and a low bioavailability of fluoride ingested together with milk. Another factor contributing to lower plasma fluoride levels in juveniles compared to adults is the rapid clearance of fluoride from blood plasma in the former due to their intense skeletal growth. The combined action of these mechanisms is considered to explain why in kangaroos from high-fluoride areas, the (early-formed) first molars are not affected by dental fluorosis while the (later-formed) third and fourth molars regularly exhibit marked to severe fluorotic lesions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evaluation of dentinal defect formation after root canal preparation with two reciprocating systems and hand instruments: an in vitro study

PubMed Central

Helvacioglu-Yigit, Dilek; Aydemir, Seda; Yilmaz, Ayca

2015-01-01

The purpose of this study was to evaluate the presence of dentinal defects after root canal preparation with hand instruments and two different reciprocating instruments. Sixty freshly extracted mandibular incisor teeth were selected for this in vitro study. On the basis of root length, mesiodistal and buccolingual dimensions, the teeth were allocated into three identical experimental groups (n = 15) and one control group (n = 15). The teeth in the control group were left unprepared. The other groups were: stainless steel hand instruments, WaveOne® Primary instruments and RECIPROC® R25 instruments. The reciprocating instruments were used with a reciprocating gentle in-and-out motion in a torque-limited electric motor at the appropriate preset mode. Horizontal sections were made 3, 6 and 9 mm from the apex. Samples were stained with methylene blue and viewed through a stereomicroscope. The presence of dentinal defects (fractures, incomplete cracks and craze lines) and their locations were investigated by two endodontists. These data were analysed statistically by Fisher's exact and chi-square tests. No defects were observed in the unprepared group. All instruments caused dentinal defects, with no significant differences between the instrument systems. All experimental groups demonstrated significantly more defects at the 3-mm level in comparison with the unprepared group (p = 0.032). At the other levels, there was no significant difference between the experimental groups and the control group. The use of hand or reciprocating instruments could induce the formation of dentinal defects during root canal preparation. PMID:26019654

Restorative therapy for erosive lesions.

PubMed

Lambrechts, P; Van Meerbeek, B; Perdigão, J; Gladys, S; Braem, M; Vanherle, G

1996-04-01

More needs to be learned about the etiology of erosion lesions before they can be accurately diagnosed, confidently treated and, more importantly, prevented. The treatment is dependent on the location and the degree of erosion. The decision to treat an erosion lesion should be based on careful consideration of the etiology and progression of the condition. Reasons for restoring noncarious enamel/dentin lesions are discussed and various therapeutic measures are provided. Preventive and restorative therapeutic measures for noncarious abrasive/ erosive lesions are proposed such as: a change of dietary or behavior patterns; application of desensitization products; intensive fluoride therapy with or without iontophoresis; brushing with desensitizing dentifrices; adhesive penetration with dentin bonding agents; glass ionomers and compomers; resin composites; composite or porcelain veneers; crown and bridge work; occlusal adjustments and nightguard fabrication if the abfraction factor coincides. The clinical durability of restorative therapy and important clinical factors related to the restoration of multifactorial defects are discussed.

Crack arrest within teeth at the dentinoenamel junction caused by elastic modulus mismatch.

PubMed

Bechtle, Sabine; Fett, Theo; Rizzi, Gabriele; Habelitz, Stefan; Klocke, Arndt; Schneider, Gerold A

2010-05-01

Enamel and dentin compose the crowns of human teeth. They are joined at the dentinoenamel junction (DEJ) which is a very strong and well-bonded interface unlikely to fail within healthy teeth despite the formation of multiple cracks within enamel during a lifetime of exposure to masticatory forces. These cracks commonly are arrested when reaching the DEJ. The phenomenon of crack arrest at the DEJ is described in many publications but there is little consensus on the underlying cause and mechanism. Explanations range from the DEJ having a larger toughness than both enamel and dentin up to the assumption that not the DEJ itself causes crack arrest but the so-called mantle dentin, a thin material layer close to the DEJ that is somewhat softer than the bulk dentin. In this study we conducted 3-point bending experiments with bending bars consisting of the DEJ and surrounding enamel and dentin to investigate crack propagation and arrest within the DEJ region. Calculated stress intensities around crack tips were found to be highly influenced by the elastic modulus mismatch between enamel and dentin and hence, the phenomenon of crack arrest at the DEJ could be explained accordingly via this elastic modulus mismatch. Copyright 2010 Elsevier Ltd. All rights reserved.

Davallialactone reduces inflammation and repairs dentinogenesis on glucose oxidase-induced stress in dental pulp cells.

PubMed

Lee, Young-Hee; Kim, Go-Eun; Song, Yong-Beom; Paudel, Usha; Lee, Nan-Hee; Yun, Bong-Sik; Yu, Mi-Kyung; Yi, Ho-Keun

2013-11-01

The chronic nature of diabetes mellitus (DM) raises the risk of oral complication diseases. In general, DM causes oxidative stress to organs. This study aimed to evaluate the cellular change of dental pulp cells against glucose oxidative stress by glucose oxidase with a high glucose state. The purpose of this study was to test the antioxidant character of davallialactone and to reduce the pathogenesis of dental pulp cells against glucose oxidative stress. The glucose oxidase with a high glucose concentration was tested for hydroxy peroxide (H2O2) production, cellular toxicity, reactive oxygen species (ROS) formation, induction of inflammatory molecules and disturbance of dentin mineralization in human dental pulp cells. The anti-oxidant effect of Davallilactone was investigated to restore dental pulp cells' vitality and dentin mineralization via reduction of H2O2 production, cellular toxicity, ROS formation and inflammatory molecules. The treatment of glucose oxidase with a high glucose concentration increased H2O2 production, cellular toxicity, and inflammatory molecules and disturbed dentin mineralization by reducing pulp cell activity. However, davallialactone reduced H2O2 production, cellular toxicity, ROS formation, inflammatory molecules, and dentin mineralization disturbances even with a long-term glucose oxidative stress state. The results of this study imply that the development of oral complications is related to the irreversible damage of dental pulp cells by DM-induced oxidative stress. Davallialactone, a natural antioxidant, may be useful to treat complicated oral disease, representing an improvement for pulp vital therapy. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Bond strength of different adhesives to normal and caries-affected dentins.

PubMed

Xuan, Wei; Hou, Ben-xiang; Lü, Ya-lin

2010-02-05

Currently, several systems of dentin substrate-reacting adhesives are available for use in the restorative treatment against caries. However, the bond effectiveness and property of different adhesive systems to caries-affected dentin are not fully understood. The objective of this study was to evaluate the bond strength of different adhesives to both normal dentin (ND) and caries-affected dentin (CAD) and to analyze the dentin/adhesive interfacial characteristics. Twenty eight extracted human molars with coronal medium carious lesions were randomly assigned to four groups according to adhesives used. ND and CAD were bonded with etch-and-rinse adhesive Adper Single Bond 2 (SB2) or self-etching adhesives Clearfil SE Bond (CSE), Clearfil S(3) Bond (CS3), iBond GI (IB). Rectangular sticks of resin-dentin bonded interfaces 0.9 mm(2) were obtained. The specimens were subjected to microtensile bond strength (microTBS) testing at a crosshead speed of 1 mm/min. Mean microTBS was statistically analyzed with analysis of variance (ANOVA) and Student-Newman-Keuls tests. Interfacial morphologies were analyzed by Scanning Electron Microscopy (SEM). Etch-and-rinse adhesive Adper(TM) Single Bond 2 yielded high bond strength when applied to both normal and caries-affected dentin. The two-step self-etching adhesive Clearfil SE Bond generated the highest bond strength to ND among all adhesives tested but a significantly reduced strength when applied to CAD. For the one-step self-etching adhesives, Clearfil S(3) Bond and iBond GI, the bond strength was relatively low regardless of the dentin type. SEM interfacial analysis revealed that hybrid layers were thicker with poorer resin tag formation and less resin-filled lateral branches in the CAD than in the ND for all the adhesives tested. The etch-and-rinse adhesive performed more effectively to caries-affected dentin than the self-etching adhesives.

Prospective in (Primate) Dental Analysis through Tooth 3D Topographical Quantification

PubMed Central

Guy, Franck; Gouvard, Florent; Boistel, Renaud; Euriat, Adelaïde; Lazzari, Vincent

2013-01-01

The occlusal morphology of the teeth is mostly determined by the enamel-dentine junction morphology; the enamel-dentine junction plays the role of a primer and conditions the formation of the occlusal enamel reliefs. However, the accretion of the enamel cap yields thickness variations that alter the morphology and the topography of the enamel–dentine junction (i.e., the differential deposition of enamel by the ameloblasts create an external surface that does not necessarily perfectly parallel the enamel–dentine junction). This self-reliant influence of the enamel on tooth morphology is poorly understood and still under-investigated. Studies considering the relationship between enamel and dentine morphologies are rare, and none of them tackled this relationship in a quantitative way. Major limitations arose from: (1) the difficulties to characterize the tooth morphology in its comprehensive tridimensional aspect and (2) practical issues in relating enamel and enamel–dentine junction quantitative traits. We present new aspects of form representation based exclusively on 3D analytical tools and procedures. Our method is applied to a set of 21 unworn upper second molars belonging to eight extant anthropoid genera. Using geometrical analysis of polygonal meshes representatives of the tooth form, we propose a 3D dataset that constitutes a detailed characterization of the enamel and of the enamel–dentine junction morphologies. Also, for the first time, to our knowledge, we intend to establish a quantitative method for comparing enamel and enamel–dentine junction surfaces descriptors (elevation, inclination, orientation, etc.). New indices that allow characterizing the occlusal morphology are proposed and discussed. In this note, we present technical aspects of our method with the example of anthropoid molars. First results show notable individual variations and taxonomic heterogeneities for the selected topographic parameters and for the pattern and strength of association between enamel–dentine junction and enamel, the enamel cap altering in different ways the “transcription” of the enamel–dentine junction morphology. PMID:23826088

Phase, compositional, and morphological changes of human dentin after Nd:YAG laser treatment.

PubMed

Lin, C P; Lee, B S; Lin, F H; Kok, S H; Lan, W H

2001-06-01

Although techniques for repairing root fracture have been proposed, the prognosis is generally poor. If the fusion of a root fracture by laser is possible, it will offer an alternative to extraction. Our group has attempted to use lasers to fuse a low melting-point bioactive glass to fractured dentin. This report is focused on the phase, compositional, and morphological changes observed by means of X-ray diffractometer, Fourier transforming infrared spectroscopy, and scanning electron microscopy-energy dispersive X-ray spectroscopy in human dentin after exposure to Nd:YAG laser. The irradiation energies were from 150 mJ/ pulse-10 pps-4 s to 150 mJ/pulse-30 pps-4 s. After exposure to Nd:YAG laser, dentin showed four peaks on the X-ray diffractometer that corresponding to a-tricalcium phosphate (TCP) and beta-TCP at 20 = 30.78 degrees/34.21 degrees and 32.47 degrees/33.05 degrees, respectively. The peaks of a-TCP and beta-TCP gradually increased in intensity with the elevation of irradiation energy. In Fourier transforming infrared analysis, two absorption bands at 2200 cm(-1) and 2015 cm(-1) could be traced on dentin treated by Nd:YAG laser with the irradiation energies beyond 150 mJ/pulse-10 pps-4 s. The energy dispersive X-ray results showed that the calcium/phosphorus ratios of the irradiated area proportionally increased with the elevation of irradiation energy. The laser energies of 150 mJ/ pulse-30 pps-4 s and 150 mJ/pulse-20 pps-4 s could result in the a-TCP formation and collagen breakdown. However, the formation of glass-like melted substances without a-TCP at the irradiated site was induced by the energy output of 150 mJ/ pulse-10 pps-4 s. Scanning electron micrographs also revealed that the laser energy of 150 mJ/ pulse-10 pps-4 s was sufficient to prompt melting and recrystallization of dentin crystals without cracking. Therefore, we suggest that the irradiation energy of Nd:YAG laser used to fuse a low melting-point bioactive glass to dentin is 150 mJ/ pulse-10 pps-4 s.

Electrostatic interactions lead to the formation of asymmetric collagen-phosphophoryn aggregates.

PubMed

Dahl, Thomas; Veis, Arthur

2003-01-01

In bone and dentin the formation and mineralization of the extra cellular matrix structure is a complex process highly dependent on intermolecular interactions. In dentin, the phosphophoryns (PP) and type I collagen (COL1) are the major constituents implicated in mineralization. Thus, as a first step in understanding the tissue organization, we have initiated a study of their interaction as a function of pH, ionic strength, and relative concentrations or mixing ratios. Complex formation has been analyzed by dynamic light scattering to detect aggregate formation and by rotary shadowing electron microscopy (EM) to determine aggregate shape. The EM data showed that at the pH values studied, the PP-COL1 interaction leads to the formation of large fibrillar aggregates in which the PP are present along the fibril surfaces. The quantitative phase distribution data showed a 1/1 molar equivalence at the maximum aggregation point, not at electrostatic PP-COL1 equivalence. As the ionic strength was raised, the PP-COL1 aggregates became smaller but the binding and asymmetric fibrillar aggregation persisted. In EM, the PP appear as dense spheres. Along the surfaces of the collagen aggregates, the PP are larger and more open or extended, suggesting that COL1-bound PP may undergo a conformational change, opening up so that a single PP molecule might interact with and electrostatically link several COL1 molecules. This might have important implications for dentin structure, stability, and mineralization.

A mathematical model for calculation of 90Sr absorbed dose in dental tissues: elaboration and comparison to EPR measurements.

PubMed

Shishkina, E A; Lyubashevskii, N M; Tolstykh, E I; Ignatiev, E A; Betenekova, T A; Nikiforov, S V

2001-09-01

A mathematical model for calculation of the 90Sr absorbed doses in dental tissues is presented. The results of the Monte-Carlo calculations are compared to the data obtained by EPR measurements of dental tissues. Radiometric measurements of the 90Sr concentrations. TLD and EPR dosimetry investigations were performed in animal (dog) study. The importance of the irregular 90Sr distribution in the dentine for absorbed dose formation has been shown. The dominant dose formation factors (main source-tissues) were identified for the crown dentine and enamel. The model has shown agreement with experimental data which allows to determine further directions of the human tooth model development.

Efficacy of Modified Bioactive Glass for Dentin Remineralization and Obstruction of Dentinal Tubules

PubMed Central

Saffarpour, Mahshid; Tahriri, Mohammadreza; Zakerzadeh, Azadeh

2017-01-01

Objectives: This study assessed the efficacy of modified bioactive glass (MBG) for dentin remineralization and obstruction of dentinal tubules. Materials and Methods: Thirty-six dentin discs were made from 20 third molars and were stored in 12% lactic acid solution for two weeks to induce demineralization. The samples were divided into three groups (n=12): 1- BG, 2- BG modified with 5% strontium (Sr) and 3- BG modified with 10% Sr. After applying the BG, the samples were stored in artificial saliva for 7, 14 and 21 days. Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray (EDX) analysis were used to assess remineralization. Also, 6 dentin discs were divided into three groups of BG, BG modified with 5% Sr and BG modified with 10% Sr, to examine tubular occlusion. The discs were etched using 0.5M of EDTA for two minutes and were stored in artificial saliva for 7 days. Changes in dentin surface morphology were evaluated under SEM. Results: Group 3 showed high rates of remineralization at days 7 and 14, although the rate decreased at day 21. Group 2 exhibited high rates of remineralization at days 7, 14 and 21. Dentinal tubules were partially occluded by BG and BG modified with 5% Sr, while they were almost completely obstructed after the use of BG modified with 10% Sr. Conclusions: Strontium increases remineralization. Addition of 10% Sr to BG enhances apatite formation; however, the apatite dissolves over time. Addition of 5% Sr to BG stabilizes the apatite lattice and increases the remineralization. PMID:29285031

Microscopic study of dental hard tissues in primary teeth with Dentinogenesis Imperfecta Type II: Correlation of 3D imaging using X-ray microtomography and polarising microscopy.

PubMed

Davis, Graham R; Fearne, Janice M; Sabel, Nina; Norén, Jörgen G

2015-07-01

The aim of this study was to examine the histological appearance of dental hard tissues in primary teeth from children with DI using conventional polarised light microscopy and correlate that with 3D imaging using X-ray microtomograpy (XMT) to gain a further understanding of the dentine structure of teeth diagnosed with dentinogenesis imperfecta. Undecalcified sections of primary teeth from patients diagnosed with Dentinogenesis Imperfecta Type II were examined using polarised light microscopy. XMT was employed for 3D-imaging and analysis of the dentine. The polarised light microscopy and XMT revealed tubular structures in the dentine seen as vacuoles coinciding with the path of normal dentinal tubules but not continuous tubules. The size of the tubules was close to that of capillaries. The largest tubular structures had a direction corresponding to where the pulp tissue would have been located during primary dentine formation. The dysfunctional mineralisation of the dentine and obliteration of the pulp evidently leaves blood vessels in the dentine which have in the main been tied off and, in the undecalcified sections, appear as vacuoles. Although from radiographs, the pulp in teeth affected by Dentinogenesis Imperfect type II appears to be completely obliterated, a network of interconnected vessels may remain. The presence of large dentinal tubules and blood vessels, or the remnants of blood vessels, could provide a pathway for bacteria from the oral cavity. This might account for why some of these teeth develop periapical abscesses in spite of apparently having no pulp. Copyright © 2015 Elsevier Ltd. All rights reserved.

Embryonic development of fin spines in Callorhinchus milii (Holocephali); implications for chondrichthyan fin spine evolution.

PubMed

Jerve, Anna; Johanson, Zerina; Ahlberg, Per; Boisvert, Catherine

2014-01-01

Fin spines are commonly known from fossil gnathostomes (jawed vertebrates) and are usually associated with paired and unpaired fins. They are less common among extant gnathostomes, being restricted to the median fins of certain chondrichthyans (cartilaginous fish), including chimaerids (elephant sharks) and neoselachians (sharks, skates, and rays). Fin spine growth is of great interest and relevance but few studies have considered their evolution and development. We investigated the development of the fin spine of the chimaerid Callorhinchus milii using stained histological sections from a series of larval, hatchling, and adult individuals. The lamellar trunk dentine of the Callorhinchus spine first condenses within the mesenchyme, rather than at the contact surface between mesenchyme and epithelium, in a manner more comparable to dermal bone formation than to normal odontode development. Trabecular dentine forms a small component of the spine under the keel; it is covered externally with a thin layer of lamellar trunk dentine, which is difficult to distinguish in sectioned adult spines. We suggest that the distinctive characteristics of the trunk dentine may reflect an origin through co-option of developmental processes involved in dermal bone formation. Comparison with extant Squalus and a range of fossil chondrichthyans shows that Callorhinchus is more representative than Squalus of generalized chondrichthyan fin-spine architecture, highlighting its value as a developmental model organism. © 2014 Wiley Periodicals, Inc.

Enamel Matrix Derivative Promote Primary Human Pulp Cell Differentiation and Mineralization

PubMed Central

Riksen, Elisabeth Aurstad; Landin, Maria A.; Reppe, Sjur; Nakamura, Yukio; Lyngstadaas, Ståle Petter; Reseland, Janne E.

2014-01-01

Enamel matrix derivative (EMD) has been found to induce reactive dentin formation; however the molecular mechanisms involved are unclear. The effect of EMD (5–50 μg/mL) on primary human pulp cells were compared to untreated cells and cells incubated with 10−8 M dexamethasone (DEX) for 1, 2, 3, 7, and 14 days in culture. Expression analysis using Affymetrix microchips demonstrated that 10 μg/mL EMD regulated several hundred genes and stimulated the gene expression of proteins involved in mesenchymal proliferation and differentiation. Both EMD and DEX enhanced the expression of amelogenin (amel), and the dentinogenic markers dentin sialophosphoprotein (DSSP) and dentin matrix acidic phosphoprotein 1 (DMP1), as well as the osteogenic markers osteocalcin (OC, BGLAP) and collagen type 1 (COL1A1). Whereas, only EMD had effect on alkaline phosphatase (ALP) mRNA expression, the stimulatory effect were verified by enhanced secretion of OC and COL1A from EMD treated cells, and increased ALP activity in cell culture medium after EMD treatment. Increased levels of interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemoattractant proteins (MCP-1) in the cell culture medium were also found. Consequently, the suggested effect of EMD is to promote differentiation of pulp cells and increases the potential for pulpal mineralization to favor reactive dentine formation. PMID:24857913

A study of cavity preparation by Er:YAG laser. Effects on the marginal leakage of composite resin restoration.

PubMed

Shigetani, Yoshimi; Tate, Yasuaki; Okamoto, Akira; Iwaku, Masaaki; Abu-Bakr, Neamat

2002-09-01

The purpose of this study was to evaluate marginal leakage of composite resin restoration from cavities prepared by Er:YAG laser. The observation of the dentin surface after the application of laser irradiation was performed by LSM, the cutting surface showed a rough surface similar to scales, and exposed dentinal tubules were observed without striations or a smeared layer formation that were observed when using a rotary cutting device. Leakage tests revealed no significant differences in the marginal seal for both enamel and dentin between cavities prepared by Er:YAG laser irradiation and when using an air-turbine. In this study, the usefulness of cavity preparation by Er:YAG laser irradiation in composite resin restoration was suggested.

An evaluation of smear layer with various desensitizing agents after tooth preparation.

PubMed

Zaimoglu, A; Aydin, A K

1992-09-01

According to hydrodynamics, any agent blocking the dentinal tubules reduces the flow of fluids and diminishes hypersensitivity. The properties of the desensitizing agents that sponsor tubular occlusion and the barrier efficiency resulting from the interaction of the smear layer with test materials were examined with the scanning electron microscope and energy-dispersive x-ray microanalysis. Selected dentinal desensitizing was accomplished with burnishing procedures, cavity varnish, calcium hydroxide, and topical fluoride. Subjective evaluations were also recorded clinically after tooth preparation. This investigation indicated that the smear layer did not protect against zinc phosphate cement, and that cavity varnish prevented the formation of the smear plugs. The smear layer and plugs were basically composed of calcium and phosphorus, the major ingredients of dentin.

Extracellular dextran and DNA affect the formation of Enterococcus faecalis biofilms and their susceptibility to 2% chlorhexidine.

PubMed

Li, Weilan; Liu, Hongyan; Xu, Qiong

2012-07-01

Enterococcus faecalis is frequently recovered from root-filled teeth with refractory apical periodontitis. The ability of E. faecalis to form a matrix-encased biofilm contributes to its pathogenicity; however, the role of extracellular dextran and DNA in biofilm formation and its effect on the susceptibility of the biofilm to chlorhexidine remains poorly understood. E. faecalis biofilms were incubated on dentin blocks. The effect of a dextran-degrading enzyme (dextranase) and DNase I on the adhesion of E. faecalis to dentin was measured using the colony-forming unit (CFU) counting method. CFU assays and confocal laser scanning microscopy were used to investigate the influence of dextranase and DNase I on the antimicrobial activity of 2% chlorhexidine. The CFU count assays indicated that the formation of biofilms by E. faecalis was reduced in cells treated with dextranase or DNase I compared with that in untreated cells (P < .05). In addition, we found that treating E. faecalis biofilms with dextranase or DNase I effectively sensitized the biofilms to 2% chlorhexidine (P < .05). Both dextranase and DNase I decrease the adhesion of E. faecalis to dentin and sensitized E. faecalis biofilms to 2% chlorhexidine. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Mineral density volume gradients in normal and diseased human tissues

DOE PAGES

Djomehri, Sabra I.; Candell, Susan; Case, Thomas; ...

2015-04-09

Clinical computed tomography provides a single mineral density (MD) value for heterogeneous calcified tissues containing early and late stage pathologic formations. The novel aspect of this study is that, it extends current quantitative methods of mapping mineral density gradients to three dimensions, discretizes early and late mineralized stages, identifies elemental distribution in discretized volumes, and correlates measured MD with respective calcium (Ca) to phosphorus (P) and Ca to zinc (Zn) elemental ratios. To accomplish this, MD variations identified using polychromatic radiation from a high resolution micro-computed tomography (micro-CT) benchtop unit were correlated with elemental mapping obtained from a microprobe X-raymore » fluorescence (XRF) using synchrotron monochromatic radiation. Digital segmentation of tomograms from normal and diseased tissues (N=5 per group; 40-60 year old males) contained significant mineral density variations (enamel: 2820-3095mg/cc, bone: 570-1415mg/cc, cementum: 1240-1340mg/cc, dentin: 1480-1590mg/cc, cementum affected by periodontitis: 1100-1220mg/cc, hypomineralized carious dentin: 345-1450mg/cc, hypermineralized carious dentin: 1815-2740mg/cc, and dental calculus: 1290-1770mg/cc). A plausible linear correlation between segmented MD volumes and elemental ratios within these volumes was established, and Ca/P ratios for dentin (1.49), hypomineralized dentin (0.32-0.46), cementum (1.51), and bone (1.68) were observed. Furthermore, varying Ca/Zn ratios were distinguished in adapted compared to normal tissues, such as in bone (855-2765) and in cementum (595-990), highlighting Zn as an influential element in prompting observed adaptive properties. Hence, results provide insights on mineral density gradients with elemental concentrations and elemental footprints that in turn could aid in elucidating mechanistic processes for pathologic formations.« less

Mineral density volume gradients in normal and diseased human tissues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Djomehri, Sabra I.; Candell, Susan; Case, Thomas

Clinical computed tomography provides a single mineral density (MD) value for heterogeneous calcified tissues containing early and late stage pathologic formations. The novel aspect of this study is that, it extends current quantitative methods of mapping mineral density gradients to three dimensions, discretizes early and late mineralized stages, identifies elemental distribution in discretized volumes, and correlates measured MD with respective calcium (Ca) to phosphorus (P) and Ca to zinc (Zn) elemental ratios. To accomplish this, MD variations identified using polychromatic radiation from a high resolution micro-computed tomography (micro-CT) benchtop unit were correlated with elemental mapping obtained from a microprobe X-raymore » fluorescence (XRF) using synchrotron monochromatic radiation. Digital segmentation of tomograms from normal and diseased tissues (N=5 per group; 40-60 year old males) contained significant mineral density variations (enamel: 2820-3095mg/cc, bone: 570-1415mg/cc, cementum: 1240-1340mg/cc, dentin: 1480-1590mg/cc, cementum affected by periodontitis: 1100-1220mg/cc, hypomineralized carious dentin: 345-1450mg/cc, hypermineralized carious dentin: 1815-2740mg/cc, and dental calculus: 1290-1770mg/cc). A plausible linear correlation between segmented MD volumes and elemental ratios within these volumes was established, and Ca/P ratios for dentin (1.49), hypomineralized dentin (0.32-0.46), cementum (1.51), and bone (1.68) were observed. Furthermore, varying Ca/Zn ratios were distinguished in adapted compared to normal tissues, such as in bone (855-2765) and in cementum (595-990), highlighting Zn as an influential element in prompting observed adaptive properties. Hence, results provide insights on mineral density gradients with elemental concentrations and elemental footprints that in turn could aid in elucidating mechanistic processes for pathologic formations.« less

Mineral density volume gradients in normal and diseased human tissues.

PubMed

Djomehri, Sabra I; Candell, Susan; Case, Thomas; Browning, Alyssa; Marshall, Grayson W; Yun, Wenbing; Lau, S H; Webb, Samuel; Ho, Sunita P

2015-01-01

Clinical computed tomography provides a single mineral density (MD) value for heterogeneous calcified tissues containing early and late stage pathologic formations. The novel aspect of this study is that, it extends current quantitative methods of mapping mineral density gradients to three dimensions, discretizes early and late mineralized stages, identifies elemental distribution in discretized volumes, and correlates measured MD with respective calcium (Ca) to phosphorus (P) and Ca to zinc (Zn) elemental ratios. To accomplish this, MD variations identified using polychromatic radiation from a high resolution micro-computed tomography (micro-CT) benchtop unit were correlated with elemental mapping obtained from a microprobe X-ray fluorescence (XRF) using synchrotron monochromatic radiation. Digital segmentation of tomograms from normal and diseased tissues (N=5 per group; 40-60 year old males) contained significant mineral density variations (enamel: 2820-3095 mg/cc, bone: 570-1415 mg/cc, cementum: 1240-1340 mg/cc, dentin: 1480-1590 mg/cc, cementum affected by periodontitis: 1100-1220 mg/cc, hypomineralized carious dentin: 345-1450 mg/cc, hypermineralized carious dentin: 1815-2740 mg/cc, and dental calculus: 1290-1770 mg/cc). A plausible linear correlation between segmented MD volumes and elemental ratios within these volumes was established, and Ca/P ratios for dentin (1.49), hypomineralized dentin (0.32-0.46), cementum (1.51), and bone (1.68) were observed. Furthermore, varying Ca/Zn ratios were distinguished in adapted compared to normal tissues, such as in bone (855-2765) and in cementum (595-990), highlighting Zn as an influential element in prompting observed adaptive properties. Hence, results provide insights on mineral density gradients with elemental concentrations and elemental footprints that in turn could aid in elucidating mechanistic processes for pathologic formations.

Effect of ProTaper Gold, Self-Adjusting File, and XP-endo Shaper Instruments on Dentinal Microcrack Formation: A Micro-computed Tomographic Study.

PubMed

Bayram, H Melike; Bayram, Emre; Ocak, Mert; Uygun, Ahmet Demirhan; Celik, Hakan Hamdi

2017-07-01

The aim of the present study was to evaluate the frequency of dentinal microcracks observed after root canal preparation with ProTaper Universal (PTU; Dentsply Tulsa Dental Specialties, Tulsa, OK), ProTaper Gold (PTG; Dentsply Tulsa Dental Specialties), Self-Adjusting File (SAF; ReDent Nova, Ra'anana, Israel), and XP-endo Shaper (XP; FKG Dentaire, La Chaux-de-Fonds, Switzerland) instruments using micro-computed tomographic (CT) analysis. Forty extracted human mandibular premolars having single-canal and straight root were randomly assigned to 4 experimental groups (n = 10) according to the different nickel-titanium systems used for root canal preparation: PTU, PTG, SAF, and XP. In the SAF and XP groups, the canals were first prepared with a K-file until #25 at the working length, and then the SAF or XP files were used. The specimens were scanned using high-resolution micro-computed tomographic imaging before and after root canal preparation. Afterward, preoperative and postoperative cross-sectional images of the teeth were screened to identify the presence of dentinal defects. For each group, the number of microcracks was determined as a percentage rate. The McNemar test was used to determine significant differences before and after instrumentation. The level of significance was set at P ≤ .05. The PTU system significantly increased the percentage rate of microcracks compared with preoperative specimens (P < .05). No new dentinal microcracks were observed in the PTG, SAF, or XP groups. Root canal preparations with the PTG, SAF, and XP systems did not induce the formation of new dentinal microcracks on straight root canals of mandibular premolars. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Mineral Density Volume Gradients in Normal and Diseased Human Tissues

PubMed Central

Djomehri, Sabra I.; Candell, Susan; Case, Thomas; Browning, Alyssa; Marshall, Grayson W.; Yun, Wenbing; Lau, S. H.; Webb, Samuel; Ho, Sunita P.

2015-01-01

Clinical computed tomography provides a single mineral density (MD) value for heterogeneous calcified tissues containing early and late stage pathologic formations. The novel aspect of this study is that, it extends current quantitative methods of mapping mineral density gradients to three dimensions, discretizes early and late mineralized stages, identifies elemental distribution in discretized volumes, and correlates measured MD with respective calcium (Ca) to phosphorus (P) and Ca to zinc (Zn) elemental ratios. To accomplish this, MD variations identified using polychromatic radiation from a high resolution micro-computed tomography (micro-CT) benchtop unit were correlated with elemental mapping obtained from a microprobe X-ray fluorescence (XRF) using synchrotron monochromatic radiation. Digital segmentation of tomograms from normal and diseased tissues (N=5 per group; 40-60 year old males) contained significant mineral density variations (enamel: 2820-3095mg/cc, bone: 570-1415mg/cc, cementum: 1240-1340mg/cc, dentin: 1480-1590mg/cc, cementum affected by periodontitis: 1100-1220mg/cc, hypomineralized carious dentin: 345-1450mg/cc, hypermineralized carious dentin: 1815-2740mg/cc, and dental calculus: 1290-1770mg/cc). A plausible linear correlation between segmented MD volumes and elemental ratios within these volumes was established, and Ca/P ratios for dentin (1.49), hypomineralized dentin (0.32-0.46), cementum (1.51), and bone (1.68) were observed. Furthermore, varying Ca/Zn ratios were distinguished in adapted compared to normal tissues, such as in bone (855-2765) and in cementum (595-990), highlighting Zn as an influential element in prompting observed adaptive properties. Hence, results provide insights on mineral density gradients with elemental concentrations and elemental footprints that in turn could aid in elucidating mechanistic processes for pathologic formations. PMID:25856386

The effects of different nickel-titanium instruments on dentinal microcrack formations during root canal preparation.

PubMed

Ustun, Yakup; Aslan, Tugrul; Sagsen, Burak; Kesim, Bertan

2015-01-01

The aim of the present study was to investigate the incidence of dentinal microcracks caused by different preparation techniques. 120 extracted human mandibular incisor teeth were divided into five experimental groups and one control group (n = 20): Group 1: Hand preparation with balanced force technique up to #25 K-file. Group 2: Preparation with only ProTaper F2 instrument in a reciprocating movement. Group 3: Preparation with Reciproc R25 instrument in a reciprocating movement. Group 4: Preparation with ProTaper instruments up to F2 instrument. Group 5: Preparation with ProTaper Next instruments up to X2 instrument. No procedure was applied to control group. The roots were sectioned horizontally at 3, 6 and 9 mm from the apex and examined. Absence or presence of dentinal microcracks was noted. The Chi-square test was performed to compare the appearance of cracked roots between all groups. There were no significant differences among the groups (P > 0.05). In conclusion, except the hand file and control group, all experimental groups showed microcrack formations.

Domain of dentine sialoprotein mediates proliferation and differentiation of human periodontal ligament stem cells.

PubMed

Ozer, Alkan; Yuan, Guohua; Yang, Guobin; Wang, Feng; Li, Wentong; Yang, Yuan; Guo, Feng; Gao, Qingping; Shoff, Lisa; Chen, Zhi; Gay, Isabel C; Donly, Kevin J; MacDougall, Mary; Chen, Shuo

2013-01-01

Classic embryological studies have documented the inductive role of root dentin on adjacent periodontal ligament differentiation.  The biochemical composition of root dentin includes collagens and cleavage products of dentin sialophosphoprotein (DSPP), such as dentin sialoprotein (DSP).  The high abundance of DSP in root dentin prompted us to ask the question whether DSP or peptides derived thereof would serve as potent biological matrix components to induce periodontal progenitors to further differentiate into periodontal ligament cells. Here, we test the hypothesis that domain of DSP influences cell fate. In situ hybridization and immunohistochemical analyses showed that the COOH-terminal DSP domain is expressed in mouse periodontium at various stages of root development. The recombinant COOH-terminal DSP fragment (rC-DSP) enhanced attachment and migration of human periodontal ligament stem cells (PDLSC), human primary PDL cells without cell toxicity. rC-DSP induced PDLSC cell proliferation as well as differentiation and mineralization of PDLSC and PDL cells by formation of mineralized tissue and ALPase activity. Effect of rC-DSP on cell proliferation and differentiation was to promote gene expression of tooth/bone-relate markers, transcription factors and growth factors. The results for the first time showed that rC-DSP may be one of the components of cell niche for stimulating stem/progenitor cell proliferation and differentiation and a natural scaffold for periodontal regeneration application.

Domain of Dentine Sialoprotein Mediates Proliferation and Differentiation of Human Periodontal Ligament Stem Cells

PubMed Central

Yang, Guobin; Wang, Feng; Li, Wentong; Yang, Yuan; Guo, Feng; Gao, Qingping; Shoff, Lisa; Chen, Zhi; Gay, Isabel C.; Donly, Kevin J.; MacDougall, Mary; Chen, Shuo

2013-01-01

Classic embryological studies have documented the inductive role of root dentin on adjacent periodontal ligament differentiation.  The biochemical composition of root dentin includes collagens and cleavage products of dentin sialophosphoprotein (DSPP), such as dentin sialoprotein (DSP).  The high abundance of DSP in root dentin prompted us to ask the question whether DSP or peptides derived thereof would serve as potent biological matrix components to induce periodontal progenitors to further differentiate into periodontal ligament cells. Here, we test the hypothesis that domain of DSP influences cell fate. In situ hybridization and immunohistochemical analyses showed that the COOH-terminal DSP domain is expressed in mouse periodontium at various stages of root development. The recombinant COOH-terminal DSP fragment (rC-DSP) enhanced attachment and migration of human periodontal ligament stem cells (PDLSC), human primary PDL cells without cell toxicity. rC-DSP induced PDLSC cell proliferation as well as differentiation and mineralization of PDLSC and PDL cells by formation of mineralized tissue and ALPase activity. Effect of rC-DSP on cell proliferation and differentiation was to promote gene expression of tooth/bone-relate markers, transcription factors and growth factors. The results for the first time showed that rC-DSP may be one of the components of cell niche for stimulating stem/progenitor cell proliferation and differentiation and a natural scaffold for periodontal regeneration application. PMID:24400037

Tributyltin impairs dentin mineralization and enamel formation in cultured mouse embryonic molar teeth.

PubMed

Salmela, Eija; Sahlberg, Carin; Alaluusua, Satu; Lukinmaa, Pirjo-Liisa

2008-11-01

Tributyltin (TBT), earlier used as an antifouling agent in marine paints, causes damage to the aquatic ecosystem, for example, impaired shell calcification in oysters. TBT affects hard tissue mineralization even in mammals: delayed bone mineralization has been observed in rodents exposed to TBT in utero. To see if TBT interferes with tooth development, especially dental hard tissue formation, we exposed mouse E18 mandibular first and second molars to 0.1, 0.5, 1.0, and 2.0 microM TBT chloride in organ culture for 7-12 days. The amount of enamel was assessed and the sizes of the first molars were measured from photographs taken after the culture. TBT concentration dependently impaired enamel formation (p < 0.001) and reduced tooth size (p < 0.001). Histological analysis showed slight arrest of dentin mineralization and enamel formation in first molars exposed to 0.1 microM TBT. At the concentration of 1.0 microM the effect was overt. The differentiation of ameloblasts in the mesial cusps was retarded but TBT had no effect on odontoblast morphology. The dental epithelium showed enhanced apoptosis. The failure of ameloblasts to form enamel was likely to be secondary to the effect of TBT on dentin mineralization. In the second molars, where predentin deposition had not started, ameloblasts and odontoblasts were nonpolarized and proliferative. The results showed that TBT concentration dependently impairs dental hard tissue formation and reduces tooth size in cultured mouse embryonic molars. The effects depend on the stage of tooth development at the start of exposure and may involve epithelial-mesenchymal interactions.

The effect of silver fluoride and potassium iodide on the bond strength of auto cure glass ionomer cement to dentine.

PubMed

Knight, G M; McIntyre, J M; Mulyani

2006-03-01

Diamine silver fluoride (Ag(NH3)2F), referred to as AgF, has been shown to reduce the incidence of caries in primary dentitions. The clinical application of this material has been limited by staining associated with both teeth and restorative materials. The application of potassium iodide (KI) after AgF eliminates stain formation. There is a lack of information as to how the addition of AgF followed by KI may affect the bond strength to dentine. The purpose of this study was to compare the bond strengths of auto cure glass ionomer cement to dentine surfaces that had been treated with AgF and KI and without treatment. Ten recently extracted human third molars were embedded into methyl methacrylate resin and sliced to form a square block of exposed dentine surfaces. Each of the four surfaces were treated by one of the following procedures: (a) etching with 37 per cent phosphoric acid; (b) applying GC dentine conditioner; (c) etching, followed by application of AgF/KI then washing off the precipitate and air drying; and (d) etching, applying AgF/KI and air drying the reaction products on the surface. Fuji VII auto cure glass ionomer cement was bonded onto each sample and fracture tested. The dentine samples treated with AgF/KI followed by washing away the precipitate and air drying had bond strengths (2.83 MPa) not significantly different from samples that had been conditioned (2.40 MPa). Samples where the AgF/KI precipitate had been air dried onto the dentine surface had significantly lower bond strengths (1.49 MPa) than the washed samples. Samples that were etched had significantly lower bond strengths (1.91MPa) than the conditioned samples. This study found that the application of AgF/KI to etched dentine samples followed by washing off the precipitate, created bond strengths that were not significantly different to conditioned samples. Leaving the AgF/KI precipitate on the dentine surface significantly reduced the bond strength of auto cured glass ionomer cement to dentine. Washing away the reaction products and air drying is recommended as the clinical protocol for using AgF and KI on dentine surfaces prior to application of an auto cure glass ionomer cement.

Variation on Molecular Structure, Crystallinity, and Optical Properties of Dentin Due to Nd:YAG Laser and Fluoride Aimed at Tooth Erosion Prevention

PubMed Central

Freitas, Anderson Z.; Bachmann, Luciano; Benetti, Carolina; Ana, Patricia A.

2018-01-01

This in vitro study evaluated the compositional, crystalline, and morphological effects promoted by Nd:YAG laser on root dentin, and verified the effects of laser and topical acidulated phosphate fluoride application (APF-gel) on dentin erosion. 180 bovine dentin slabs were randomized into 4 groups (n = 45): G1–untreated, G2–APF-gel (1.23% F−, 4 min), G3–Nd:YAG (1064 nm, 84.9 J/cm2, 10 Hz), and G4–APF-gel application followed by Nd:YAG laser irradiation. The compositional, crystalline, and morphological effects promoted by treatments were investigated on five samples of each experimental group. The other samples were submitted to a 5-day, 10-day, or 15-day erosive and abrasive demineralization and remineralization cycling in order to create erosion lesions. The area and depth of lesions, as well as the optical attenuation coefficient, were assessed, and all data were statistically analysed (p < 0.05). Nd:YAG laser promoted the reduction of carbonate, the formation of tetracalcium phosphate, as well as the melting and recrystallization of the dentin surface. Laser significantly decreased the area and depth of erosion lesions and altered the optical attenuation coefficient when compared to untreated and APF-gel groups, but the association of APF-gel and laser did not promote an additional effect. Nd:YAG laser irradiation can be a promissory treatment to prevent dentin erosion and the abrasion process. PMID:29389868

The rescue of dentin matrix protein 1 (DMP1)-deficient tooth defects by the transgenic expression of dentin sialophosphoprotein (DSPP) indicates that DSPP is a downstream effector molecule of DMP1 in dentinogenesis.

PubMed

Gibson, Monica Prasad; Zhu, Qinglin; Wang, Suzhen; Liu, Qilin; Liu, Ying; Wang, Xiaofang; Yuan, Baozhi; Ruest, L Bruno; Feng, Jian Q; D'Souza, Rena N; Qin, Chunlin; Lu, Yongbo

2013-03-08

Dentin matrix protein 1 (DMP1) and dentin sialophosphoprotein (DSPP) are essential for the formation of dentin. Previous in vitro studies have indicated that DMP1 might regulate the expression of DSPP during dentinogenesis. To examine whether DMP1 controls dentinogenesis through the regulation of DSPP in vivo, we cross-bred transgenic mice expressing normal DSPP driven by a 3.6-kb rat Col1a1 promoter with Dmp1 KO mice to generate mice expressing the DSPP transgene in the Dmp1 KO genetic background (referred to as "Dmp1 KO/DSPP Tg mice"). We used morphological, histological, and biochemical techniques to characterize the dentin and alveolar bone of Dmp1 KO/DSPP Tg mice compared with Dmp1 KO and wild-type mice. Our analyses showed that the expression of endogenous DSPP was remarkably reduced in the Dmp1 KO mice. Furthermore, the transgenic expression of DSPP rescued the tooth and alveolar bone defects of the Dmp1 KO mice. In addition, our in vitro analyses showed that DMP1 and its 57-kDa C-terminal fragment significantly up-regulated the Dspp promoter activities in a mesenchymal cell line. In contrast, the expression of DMP1 was not altered in the Dspp KO mice. These results provide strong evidence that DSPP is a downstream effector molecule that mediates the roles of DMP1 in dentinogenesis.

Adhesive/Dentin Interface: The Weak Link in the Composite Restoration

PubMed Central

Spencer, Paulette; Ye, Qiang; Park, Jonggu; Topp, Elizabeth M.; Misra, Anil; Marangos, Orestes; Wang, Yong; Bohaty, Brenda S.; Singh, Viraj; Sene, Fabio; Eslick, John; Camarda, Kyle; Katz, J. Lawrence

2010-01-01

Results from clinical studies suggest that more than half of the 166 million dental restorations that were placed in the United States in 2005 were replacements for failed restorations. This emphasis on replacement therapy is expected to grow as dentists use composite as opposed to dental amalgam to restore moderate to large posterior lesions. Composite restorations have higher failure rates, more recurrent caries, and increased frequency of replacement as compared to amalgam. Penetration of bacterial enzymes, oral fluids, and bacteria into the crevices between the tooth and composite undermines the restoration and leads to recurrent decay and premature failure. Under in vivo conditions the bond formed at the adhesive/dentin interface can be the first defense against these noxious, damaging substances. The intent of this article is to review structural aspects of the clinical substrate that impact bond formation at the adhesive/dentin interface; to examine physico-chemical factors that affect the integrity and durability of the adhesive/dentin interfacial bond; and to explore how these factors act synergistically with mechanical forces to undermine the composite restoration. The article will examine the various avenues that have been pursued to address these problems and it will explore how alterations in material chemistry could address the detrimental impact of physico-chemical stresses on the bond formed at the adhesive/dentin interface. PMID:20195761

In Vitro and In Vivo Dentinogenic Efficacy of Human Dental Pulp-Derived Cells Induced by Demineralized Dentin Matrix and HA-TCP

PubMed Central

Kang, Kyung-Jung; Lee, Min Suk; Moon, Chan-Woong; Lee, Jae-Hoon

2017-01-01

Human dental pulp cells have been known to have the stem cell features such as self-renewal and multipotency. These cells are differentiated into hard tissue by addition of proper cytokines and biomaterials. Hydroxyapatite-tricalcium phosphates (HA-TCPs) are essential components of hard tissue and generally used as a biocompatible material in tissue engineering of bone. Demineralized dentin matrix (DDM) has been reported to increase efficiency of bone induction. We compared the efficiencies of osteogenic differentiation and in vivo bone formation of HA-TCP and DDM on human dental pulp stem cells (hDPSCs). DDM contains inorganic components as with HA-TCP, and organic components such as collagen type-1. Due to these components, osteoinduction potential of DDM on hDPSCs was remarkably higher than that of HA-TCP. However, the efficiencies of in vivo bone formation are similar in HA-TCP and DDM. Although osteogenic gene expression and bone formation in immunocompromised nude mice were similar levels in both cases, dentinogenic gene expression level was slightly higher in DDM transplantation than in HA-TCP. All these results suggested that in vivo osteogenic potentials in hDPSCs are induced with both HA-TCP and DDM by osteoconduction and osteoinduction, respectively. In addition, transplantation of hDPSCs/DDM might be more effective for differentiation into dentin. PMID:28761445

In Vitro and In Vivo Dentinogenic Efficacy of Human Dental Pulp-Derived Cells Induced by Demineralized Dentin Matrix and HA-TCP.

PubMed

Kang, Kyung-Jung; Lee, Min Suk; Moon, Chan-Woong; Lee, Jae-Hoon; Yang, Hee Seok; Jang, Young-Joo

2017-01-01

Human dental pulp cells have been known to have the stem cell features such as self-renewal and multipotency. These cells are differentiated into hard tissue by addition of proper cytokines and biomaterials. Hydroxyapatite-tricalcium phosphates (HA-TCPs) are essential components of hard tissue and generally used as a biocompatible material in tissue engineering of bone. Demineralized dentin matrix (DDM) has been reported to increase efficiency of bone induction. We compared the efficiencies of osteogenic differentiation and in vivo bone formation of HA-TCP and DDM on human dental pulp stem cells (hDPSCs). DDM contains inorganic components as with HA-TCP, and organic components such as collagen type-1. Due to these components, osteoinduction potential of DDM on hDPSCs was remarkably higher than that of HA-TCP. However, the efficiencies of in vivo bone formation are similar in HA-TCP and DDM. Although osteogenic gene expression and bone formation in immunocompromised nude mice were similar levels in both cases, dentinogenic gene expression level was slightly higher in DDM transplantation than in HA-TCP. All these results suggested that in vivo osteogenic potentials in hDPSCs are induced with both HA-TCP and DDM by osteoconduction and osteoinduction, respectively. In addition, transplantation of hDPSCs/DDM might be more effective for differentiation into dentin.

Autophagy in SDF-1α-mediated DPSC migration and pulp regeneration.

PubMed

Yang, Jing-Wen; Zhang, Yu-Feng; Wan, Chun-Yan; Sun, Zhe-Yi; Nie, Shuai; Jian, Shu-Juan; Zhang, Lu; Song, Guang-Tai; Chen, Zhi

2015-03-01

Critical morphological requirements for pulp regeneration are tissues replete with vascularisation, neuron formation, and dentin deposition. Autophagy was recently shown to be related to angiogenesis, neural differentiation, and osteogenesis. The present study aimed to investigate the involvement of autophagy in stromal cell-derived factor-1α (SDF-1α)-mediated dental pulp stem cell (DPSC) migration and pulp regeneration, and identify its presence during pulp revascularisation of pulpectomised dog teeth with complete apical closure. In vitro studies showed that SDF-1α enhanced DPSCs migration and optimised focal adhesion formation and stress fibre assembly, which were accompanied by autophagy. Moreover, autophagy inhibitors significantly suppressed, whereas autophagy activator substantially augmented SDF-1α-stimulated DPSCs migration. Furthermore, after ectopic transplantation of tooth fragment/silk fibroin scaffold with DPSCs into nude mice, pulp-like tissues with vascularity, well-organised fibrous matrix formation, and new dentin deposition along the dentinal wall were generated in SDF-1α-loaded samples accompanied by autophagy. More importantly, in a pulp revascularisation model in situ, SDF-1α-loaded silk fibroin scaffolds improved the de novo ingrowth of pulp-like tissues in pulpectomised mature dog teeth, which correlated with the punctuated LC3 and Atg5 expressions, indicating autophagy. Our findings provide novel insights into the pulp regeneration mechanism, and SDF-1α shows promise for future clinical application in pulp revascularisation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Smear layer-deproteinizing improves bonding of one-step self-etch adhesives to dentin.

PubMed

Thanatvarakorn, Ornnicha; Prasansuttiporn, Taweesak; Thittaweerat, Suppason; Foxton, Richard M; Ichinose, Shizuko; Tagami, Junji; Hosaka, Keiichi; Nakajima, Masatoshi

2018-03-01

Smear layer deproteinizing was proved to reduce the organic phase of smear layer covered on dentin surface. It was shown to eliminate hybridized smear layer and nanoleakage expression in resin-dentin bonding interface of two-step self-etch adhesive. This study aimed to investigate those effects on various one-step self-etch adhesives. Four different one-step self-etch adhesives were used in this study; SE One (SE), Scotchbond™ Universal (SU), BeautiBond Multi (BB), and Bond Force (BF). Flat human dentin surfaces with standardized smear layer were prepared. Smear layer deproteinizing was carried out by the application of 50ppm hypochlorous acid (HOCl) on dentin surface for 15s followed by Accel ® (p-toluenesulfinic acid salt) for 5s prior to adhesive application. No surface pretreatment was used as control. Microtensile bond strength (μTBS) and nanoleakage under TEM observation were investigated. The data were analyzed by two-way ANOVA and Tukey's post-hoc test and t-test at the significant level of 0.05. Smear layer deproteinizing significantly improved μTBS of SE, SU, and BB (p<0.001). Hybridized smear layer observed in control groups of SE, BB, and BF, and reticular nanoleakage presented throughout the hybridized complex in control groups of BB and BF were eliminated upon the smear layer deproteinizing. Smear layer deproteinizing by HOCl and Accel ® application could enhance the quality of dentin for bonding to one-step self-etch adhesives, resulting in the improving μTBS, eliminating hybridized smear layer and preventing reticular nanoleakage formation in resin-dentin bonding interface. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

A Chemical Phosphorylation-inspired Design for Type I Collagen Biomimetic Remineralization

PubMed Central

Gu, Li-sha; Kim, Jongryul; Kim, Young Kyung; Liu, Yan; Dickens, Sabine H.; Pashley, David H.; Ling, Jun-qi; Tay, Franklin R.

2010-01-01

Objectives Type I collagen alone cannot initiate tissue mineralization. Sodium trimetaphosphate (STMP) is frequently employed as a chemical phosphorylating reagent in the food industry. This study examined the feasibility of using STMP as a functional analog of matrix phosphoproteins for biomimetic remineralization of resin-bonded dentin. Methods Equilibrium adsorption and desorption studies of STMP were performed using demineralized dentin powder (DDP). Interaction between STMP and DDP was examined using Fourier-transform infrared spectroscopy. Based on those results, a bio-inspired mineralization scheme was developed for chemical phosphorylation of acid-etched dentin with STMP, followed by infiltration of the STMP-treated collagen matrix with two etch-and-rinse adhesives. Resin-dentin interfaces were remineralized in a Portland cement-simulated body fluid system, with or without the use of polyacrylic acid (PAA) as a dual biomimetic analog. Remineralized resin-dentin interfaces were examined unstained using transmission electron microscopy. Results Analysis of saturation binding curves revealed the presence of irreversible phosphate group binding sites on the surface of the DDP. FT-IR provided additional evidence of chemical interaction between STMP and DDP, with increased in the peak intensities of the P=O and P–O–C stretching modes. Those peaks returned to their original intensities after alkaline phosphatase treatment. Evidence of intrafibrillar apatite formation could be seen in incompletely resin-infiltrated, STMP-phosphorylated collagen matrices only when PAA was present in the SBF. Significance These results reinforce the importance of PAA for sequestration of amorphous calcium phosphate nanoprecursors in the biomimetic remineralization scheme. They also highlight the role of STMP as a templating analog of dentin matrix phosphoproteins for inducing intrafibrillar remineralization of apatite nanocrystals within the collagen matrix of incompletely resin-infiltrated dentin. PMID:20688381

Immunohistochemical study of dental pulp applied with 4-META/MMA-TBB adhesive resin after pulpotomy.

PubMed

Nakamura, M; Inoue, T; Shimono, M

2000-08-01

The purpose of this study was to investigate nerve regeneration and proliferative activity in amputated pulp tissue after the application of 4-META/MMA-TBB adhesive resin (4-META resin). Calcium hydroxide was used as a control material. At 3 days, fibroblast-like cells were positive for proliferating cell nuclear antigen (PCNA) in both 4-META resin- and calcium hydroxide-treated groups and were located mainly within 0.5 mm from the cut surface. Only a few fragmented neurofilament protein (NFP)-positive nerve fibers were observed in this area. At 7 and 14 days, the number of PCNA-positive cells had gradually decreased and regenerated NFP-positive nerve fibers were observed close to the cut surface of the pulp in both groups. At 21 days in the experimental group, several PCNA-positive cells were still found in the area 0.5 mm from the cut surface, and NFP-positive nerve fibers were detected about 0.15-;0.2 mm from the cut surface. In contrast, a dentin bridge was produced under the necrotic layer at 21 days in the control group. PCNA-positive cells were not found underneath the dentin bridge, but NFP-positive nerve fibers had regenerated close to it. These results suggest that although cell differentiation and nerve regeneration are delayed, wound healing occurred even after the application of 4-META resin to exposed pulp surface the same as calcium hydroxide application. Copyright 2000 John Wiley & Sons, Inc.

Combined effect of fluoride and 2,3,7,8-tetrachlorodibenzo-p-dioxin on mouse dental hard tissue formation in vitro.

PubMed

Salmela, Eija; Lukinmaa, Pirjo-Liisa; Partanen, Anna-Maija; Sahlberg, Carin; Alaluusua, Satu

2011-08-01

Fluoride interferes with enamel matrix secretion and mineralization and dentin mineralization. The most toxic dioxin congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), also impairs dental hard tissue formation and mineralization in vitro and in vivo. Our aim was to investigate in vitro whether the combined effect of sodium fluoride (NaF) and TCDD on dental hard tissue formation is potentiative. For this purpose, mandibular first and second molar tooth germs of E18 mouse embryos were cultured for 5-12 days with NaF and TCDD alone at various concentrations (2.5, 5, 10, 12.5, 15, and 20 μM and 5, 10, 12.5, and 15 nM, respectively) to determine the highest concentrations, which alone cause no or negligible effects. Morphological changes were studied from the whole tooth photographs and histological tissue sections. The concentrations found were 15 μM for NaF and 10 nM for TCDD. While at these concentrations, the effects of NaF and TCDD alone were barely detectable, the effect of simultaneous exposure on dentin and enamel formation was overt; mineralization of predentin to dentin and enamel matrix secretion and mineralization were impaired. Immunohistochemical analysis revealed that the combined exposure modified amelogenin expression by odontoblasts. Morphology of ameloblasts and the expression of amelogenin indicated that ameloblasts were still secretory. The results show that NaF and TCDD have potentiative, harmful effects on the formation of dental hard tissues. Since children can be exposed to subclinical levels of fluoride and dioxins during early childhood, coincidently with mineralization of the first permanent teeth, this finding may have clinical significance.

Catechol-Functionalized Synthetic Polymer as a Dental Adhesive to Contaminated Dentin Surface for a Composite Restoration.

PubMed

Lee, Sang-Bae; González-Cabezas, Carlos; Kim, Kwang-Mahn; Kim, Kyoung-Nam; Kuroda, Kenichi

2015-08-10

This study reports a synthetic polymer functionalized with catechol groups as dental adhesives. We hypothesize that a catechol-functionalized polymer functions as a dental adhesive for wet dentin surfaces, potentially eliminating the complications associated with saliva contamination. We prepared a random copolymer containing catechol and methoxyethyl groups in the side chains. The mechanical and adhesive properties of the polymer to dentin surface in the presence of water and salivary components were determined. It was found that the new polymer combined with an Fe(3+) additive improved bond strength of a commercial dental adhesive to artificial saliva contaminated dentin surface as compared to a control sample without the polymer. Histological analysis of the bonding structures showed no leakage pattern, probably due to the formation of Fe-catechol complexes, which reinforce the bonding structures. Cytotoxicity test showed that the polymers did not inhibit human gingival fibroblast cells proliferation. Results from this study suggest a potential to reduce failure of dental restorations due to saliva contamination using catechol-functionalized polymers as dental adhesives.

Characterization of two types of osteoclasts from human peripheral blood monocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yuasa, Kimitaka; Mori, Kouki; Ishikawa, Hitoshi

2007-05-04

The two osteoclastogenesis pathways, receptor activator nuclear factor (NF)-{kappa}B ligand (RANKL)-mediated and fusion regulatory protein-1 (FRP-1)-mediated osteoclastogenesis, have recently been reported. There were significant differences in differentiation and activation mechanisms between the two pathways. When monocytes were cultured with FRP-1 without adding M-CSF, essential for the RANKL system, TRAP-positive polykaryocyte formation occurred. FRP-1-mediated osteoclasts formed larger pits on mineralized calcium phosphate plates than RANKL+M-CSF-mediated osteoclasts did. Lacunae on dentin surfaces induced by FRP-1-mediated osteoclasts were inclined to be single and isolated. However, osteoclasts induced by RANKL+M-CSF made many connected pits on dentin surfaces as if they crawled on there. Interestingly,more » FRP-1 osteoclastogenesis was enhanced by M-CSF/IL-1{alpha}, while chemotactic behavior to the dentin slices was not effected. There were differences in pH and concentration of HCO3- at culture endpoint and in adherent feature to dentin surfaces. Our findings indicate there are two types of osteoclasts with distinct properties.« less

Catechol-Functionalized Synthetic Polymer as a Dental Adhesive to Contaminated Dentin Surface for a Composite Restoration

PubMed Central

2015-01-01

This study reports a synthetic polymer functionalized with catechol groups as dental adhesives. We hypothesize that a catechol-functionalized polymer functions as a dental adhesive for wet dentin surfaces, potentially eliminating the complications associated with saliva contamination. We prepared a random copolymer containing catechol and methoxyethyl groups in the side chains. The mechanical and adhesive properties of the polymer to dentin surface in the presence of water and salivary components were determined. It was found that the new polymer combined with an Fe3+ additive improved bond strength of a commercial dental adhesive to artificial saliva contaminated dentin surface as compared to a control sample without the polymer. Histological analysis of the bonding structures showed no leakage pattern, probably due to the formation of Fe–catechol complexes, which reinforce the bonding structures. Cytotoxicity test showed that the polymers did not inhibit human gingival fibroblast cells proliferation. Results from this study suggest a potential to reduce failure of dental restorations due to saliva contamination using catechol-functionalized polymers as dental adhesives. PMID:26176305

The influence of the Q-switched and free-running Er:YAG laser beam characteristics on the ablation of root canal dentine

NASA Astrophysics Data System (ADS)

Papagiakoumou, Eirini; Papadopoulos, Dimitrios N.; Khabbaz, Marouan G.; Makropoulou, Mersini I.; Serafetinides, Alexander A.

2004-06-01

Laser based dental treatment is attractive to many researchers. Lasers in the 3 μm region, as the Er:YAG, are suitable especially for endodontic applications. In this study a pulsed free-running and Q-switched laser was used for the ablation experiments of root canal dentine. The laser beam was either directly focused on the dental tissue or delivered to it through an infrared fiber. For different spatial beam distributions, energies, number of pulses and both laser operations the quality characteristics (crater's shape formation, ablation efficiency and surface characteristics modification) were evaluated using scanning electron microscopy (SEM). The craters produced, generally, reflect the relevant beam profile. Inhomogeneous spatial beam profiles and short pulse duration result in cracks formation and lower tissue removal efficiency, while longer pulse durations cause hard dentine fusion. Any beam profile modification, due to laser characteristics variations and the specific delivering system properties, is directly reflected in the ablation crater shape and the tissue removal efficiency. Therefore, the laser parameters, as fluence, pulse repetition rate and number of pulses, have to be carefully adjusted in relation to the desirable result.

[The dentinal smear layer. Characteristics and interactions. 2].

PubMed

Negri, P L; Eramo, S; Lotito, M; De Pino, C

1991-03-15

The Authors, after the presentation (in the first part of the Dossier) of a large literature review about the physical, chemical and clinical characteristics of formation, interaction, remotion of "smear layer" during cavity preparation in hard tooth tissue, describe the results of a scanning microelectronic research about the action as cleanser (for the dentinal cavity wall) of the CK101 (Caridex) versus wather, Tubulicid and phosphoric acid. The experimental results obtained "in vitro" show that the substance has relative action, without removing the tubular portion of "smear layer".

Lasers in Apicoectomy: A Brief Review.

PubMed

Mohammadi, Zahed; Jafarzadeh, Hamid; Shalavi, Sousan; Kinoshita, Jun-Ichiro; Giardino, Luciano

2017-02-01

Since the invention of laser, various applications for lasers in endodontics have been proposed, such as disinfection of the root canal system, canal shaping, pulp diagnosis, and apico-ectomy. One of the major applications of laser in endodontics is apicoectomy. The aim of this article is to review the benefits and drawbacks of laser applications in apicoectomy, including effect on apical seal, effect on dentin permeability, effect on postsurgery pain, effect on crack formation, effect on root-end morphology, effect on treatment outcome, and connective tissue response to laser-treated dentin.

Bonding resin thixotropy and viscosity influence on dentine bond strength.

PubMed

Niem, Thomas; Schmidt, Alexander; Wöstmann, Bernd

2016-08-01

To investigate the influence of bonding resin thixotropy and viscosity on dentine tubule penetration, blister formation and consequently on dentine bond strength as a function of air-blowing pressure (air-bp) intensity. Two HEMA-free, acetone-based, one-bottle self-etch adhesives with similar composition except disparate silica filler contents and different bonding resin viscosities were investigated. The high-filler-containing adhesive (G-Bond) featured a lower viscous bonding resin with inherent thixotropic resin (TR) properties compared to the low-filler-containing adhesive (iBond) exhibiting a higher viscous bonding resin with non-thixotropic resin (NTR) properties. Shear bond strength tests for each adhesive with low (1.5bar; 0.15MPa; n=16) and high (3.0bar; 0.30MPa; n=16) air-bp application were performed after specimen storage in distilled water (24h; 37.0±1.0°C). Results were analysed using a Student's t-test to identify statistically significant differences (p<0.05). Fracture surfaces of TR adhesive specimens were morphologically characterised by SEM. Statistically significant bond strength differences were obtained for the thixotropic resin adhesive (high-pressure: 24.6MPa, low-pressure: 9.6MPa). While high air-bp specimens provided SEM images revealing resin-plugged dentine tubules, resin tags and only marginally blister structures, low air-bp left copious droplets and open dentine tubules. In contrast, the non-thixotropic resin adhesive showed no significant bond strength differences (high-pressure: 9.3MPa, low-pressure: 7.6MPa). A pressure-dependent distinct influence of bonding resin thixotropy and viscosity on dentine bond strength has been demonstrated. Stronger adhesion with high air-bp application is explained by improved resin fluidity and facilitated resin penetration into dentine tubules. Filler particles used in adhesive systems may induce thixotropic effects in bonding resin layers, accounting for improved free-flowing resin properties. In combination with high air-bp this effect allows an easy plugging of dentine tubules and elimination of blister structures, both resulting in superior dentine bond strength. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluation of Blood Cell Attachment on Er:Yag Laser Applied Root Surface Using Scanning Electron Microscopy

PubMed Central

CEKICI, Ali; MADEN, Ilay; YILDIZ, Sercan; SAN, Tangul; ISIK, Gulden

2013-01-01

Background: Periodontal regeneration is dependent on the uninterrupted adhesion, maturation and absorption of fibrin clots to a periodontally compromised root surface. The modification of the root surface with different agents has been used for better fibrin clot formation and blood cell attachment. It is known that Er:YAG laser application on dentin removes the smear layer succesfully. Aim: The aim of this study is to observe blood cell attachment and fibrin network formation following ER:YAG laser irradiation on periodontally compromised root surfaces in comparison to chemical root conditioning techniques in vitro. Materials and methods: 40 dentin blocks prepared from freshly extracted periodontally compromised hopeless teeth. Specimens were divided in 5 groups; those applied with PBS, EDTA, Citric acid and Er:YAG. They were further divided into two groups: those which had received these applications, and the control group. The specimens were evaluated with scanning electron microscope and micrographs were taken. Smear layer and blood cell attachment scoring was performed. Results: In the Er:YAG laser applied group, smear layer were totally removed. In the blood applied specimens, better fibrin clot formation and blood cell attachment were observed in the Er:YAG group. In the group that had been applied with citric acid, the smear layer was also removed. The smear layer could not be fully removed in the EDTA group. Conclusion: Er:YAG laser application on the root dentin seems to form a suitable surface for fibrin clot formation and blood cell attachment. Further clinical studies to support these results are necessitated. PMID:23533017

Inhibitory effects of acid water prepared by an electrolysis apparatus on early plaque formation on specimens of dentine.

PubMed

Ito, K; Nishida, T; Murai, S

1996-05-01

The aim of this study was to compare the effects of acid water prepared by an electrolysis apparatus with placebo treatment on the ultrastructure of early plaque formed on dentine specimens attached to retainers in the oral cavity. Dentine specimens were taken from 12 healthy extracted human 3rd molars. 4 dentine specimens were placed in the both the right and left buccal flanges of retainers fabricated from self-setting acrylic resin. The retainers were placed on both maxillary buccal sites in 6 subjects. The test solution was acid water (AW) prepared by an electrolysis apparatus with a pH of 2.7 and an oxidation-reduction potential of more than 1100 mV. As a positive control, 0.2% chlorhexidine digluconate (CHX) solution was used and normal saline solution as a negative control. 4 specimens placed in the right and left retainers were randomly allocated to 4 treatments as follows: treatment A, washing with AW; treatment B, washing with CHX solution; treatment C, washing with normal saline; treatment D, no washing. Washing was carried out in a plastic beaker containing 30 ml of each solution for 30s 2X daily over a 7-day period. The specimens were then carefully removed from the retainers, the morphology and thickness of the plaque formed examined by SEM, and the developmental condition of the plaque analyzed statistically. The plaque on the specimens in treatments A and B consisted mainly of coccoid forms. Mature plaque formation with complex flora was seen on the specimens in treatments C and D. The mean thickness of the plaque deposits on the dentin specimens as measured on SEM photographs magnified 2000 times was 8.80 mm for treatment. A, while in treatment B it was 3.90 mm. Plaque thickness for treatment C was 24.97 mm, and for treatment D 25.67 mm. The thickness of plaque formed on the sectioned specimens was significantly less for treatments A and B than for treatments C and D. However, there was no statistically significant difference between treatments A and B, and between treatments C and D (p < 0.0001). The results of this short-term study indicate that AW washing has almost the same potential for inhibition of plaque formation as CHX washing, and is more effective for inhibiting plaque formation than washing with sterile saline. It is therefore concluded that AW may be useful as an anti-plaque agent.

TiF(4) and NaF at pH 1.2 but not at pH 3.5 are able to reduce dentin erosion.

PubMed

Wiegand, Annette; Magalhães, Ana Carolina; Sener, Beatrice; Waldheim, Elena; Attin, Thomas

2009-08-01

This study aimed to analyse and compare the protective effect of buffered (pH 3.5) and native (pH 1.2) TiF(4) in comparison to NaF solutions of same pH on dentin erosion. Bovine samples were pretreated with 1.50% TiF(4) or 2.02% NaF (both 0.48M F) solutions, each with a pH of 1.2 and 3.5. The control group received no fluoride pretreatment. Ten samples in each group were eroded with HCl (pH 2.6) for 10x60s. Erosion was analysed by determination of calcium release into the acid. Additionally, the surface and the elemental surface composition were examined by scanning electron microscopy (two samples in each group) and X-ray energy-dispersive spectroscopy in fluoridated but not eroded samples (six samples in each group). Cumulative calcium release (nmol/mm(2)) was statistically analysed by repeated measures ANOVA and one-way ANOVA at t=10min. TiF(4) and NaF at pH 1.2 decreased calcium release significantly, while TiF(4) and NaF at pH 3.5 were not effective. Samples treated with TiF(4) at pH 1.2 showed a significant increase of Ti, while NaF pretreatment increased F concentration significantly. TiF(4) at pH 1.2 led to the formation of globular precipitates occluding dentinal tubules, which could not be observed on samples treated with TiF(4) at pH 3.5. NaF at pH 1.2 but not at pH 3.5 induced the formation of surface precipitates covering dentinal tubules. Dentin erosion can be significantly reduced by TiF(4) and NaF at pH 1.2, but not at pH 3.5.

Effect of the calcium silicate-based sealer removal protocols and time-point of acid etching on the dentin adhesive interface.

PubMed

Morais, Jéssika Mayhara Pereira; Victorino, Keli Regina; Escalante-Otárola, Wilfredo Gustavo; Jordão-Basso, Keren Cristina Fagundes; Palma-Dibb, Regina Guenka; Kuga, Milton Carlos

2018-06-15

The aim of the study was to evaluate the effects when acid etching on the dentin surface was immediately performed (I) or 7 days (D) after calcium silicate-based sealer (MTA Fillapex) removal, using 95% ethanol (E) or xylol (X). First study, 60 bovine incisor dentin specimens were impregnated with sealer and divided into six groups (n = 10): (EI), E + I; (XI), X + I; (ED), E + D; (XD), X + D, (UN), untreated and (MR), mechanical removal of sealer. Scanning electron microscopy (SEM) images (500×) were obtained from each specimen and scores assessed the sealer residues persistence. Second study, 60 specimens were similarly treated; however, the specimens were restored with composite resin after the removal protocols. Hybrid layer formation was evaluated using confocal laser microscopy (1,024×). Third study, 60 specimens were similarly obtained and subjected to micro-shear test to evaluate the effects of removal protocols on the bond strength of etch-and- rinse adhesive system to dentin. XI showed the highest persistence of sealer residues (p < .05), similar to MR (p > .05). EI showed the greatest hybrid layer extension, except in relation to UN (p < .05). XI and MR presented the lowest bond strength adhesive system to dentin (p < .05). Acid etching immediately after calcium silicate-based endodontic sealer removal using xylol presented the highest residues persistence and negatively affected the adhesive interface between dentin and etch-and-rinse adhesive system. © 2018 Wiley Periodicals, Inc.

In vitro effects of two silicate-based materials, Biodentine and BioRoot RCS, on dental pulp stem cells in models of reactionary and reparative dentinogenesis

PubMed Central

Loison-Robert, Ludwig Stanislas; Berbar, Tsouria; Isaac, Juliane; Berdal, Ariane; Simon, Stéphane

2018-01-01

Background Calcium silicate-based cements are biomaterials with calcium oxide and carbonate filler additives. Their properties are close to those of dentin, making them useful in restorative dentistry and endodontics. The aim of this study was to evaluate the in vitro biological effects of two such calcium silicate cements, Biodentine (BD) and Bioroot (BR), on dental stem cells in both direct and indirect contact models. The two models used aimed to mimic reparative dentin formation (direct contact) and reactionary dentin formation (indirect contact). An original aspect of this study is the use of an interposed thin agarose gel layer to assess the effects of diffusible components from the materials. Results The two biomaterials were compared and did not modify dental pulp stem cell (DPSC) proliferation. BD and BR showed no significant cytotoxicity, although some cell death occurred in direct contact. No apoptosis or inflammation induction was detected. A striking increase of mineralization induction was observed in the presence of BD and BR, and this effect was greater in direct contact. Surprisingly, biomineralization occurred even in the absence of mineralization medium. This differentiation was accompanied by expression of odontoblast-associated genes. Exposure by indirect contact did not stimulate the induction to such a level. Conclusion These two biomaterials both seem to be bioactive and biocompatible, preserving DPSC proliferation, migration and adhesion. The observed strong mineralization induction through direct contact highlights the potential of these biomaterials for clinical application in dentin-pulp complex regeneration. PMID:29370163

Effectiveness of Photogem® activated by LED on the decontamination of artificial carious bovine dentin

NASA Astrophysics Data System (ADS)

Giusti, J. S. M.; Santos-Pinto, L.; Pizzolitto, A. C.; Kurachi, C.; Bagnato, V. S.

2006-05-01

The aim of this study was the evaluation of the effectiveness of photodynamic therapy on the decontamination of artificially induced carious bovine dentin, using Photogem® as the photosensitizer agent and an LED device as a light source. Dentin samples obtained from bovine incisors were immersed in sterile broth supplemented by Lactobacillus acidophillus 108 colony formation units (CFU) and Streptococcus mutans 108 CFU. Different concentrations of photosensitizer, PA = 1 mg/ml, PB = 2 mg/ml, and PC = 3 mg/ml, and two fluences, D = 24 J/cm2 and D = 48 J/cm2, were investigated. After CFU counting per milligram of carious dentin and statistical analysis, we observed that the photodynamic therapy (PDT) parameters used were effective for bacterial reduction in the in vitro model under study. The best result was achieved with the application of Photogem® at 2 mg/ml and photoactivated under 24 J/cm2 showing a survival factor of 0.14. At higher photosensitizer concentrations, a higher dark toxicity was observed. We propose a simple mathematical expression for the determination of PDT parameters of photosensitizer concentration and light fluence for different survival factor values. Since LED devices are simpler and cheaper compared to laser systems, it would be interesting to verify their efficacy as a light source in photodynamic therapy for the decontamination of carious dentin.

Cyclophilin B Deficiency Causes Abnormal Dentin Collagen Matrix.

PubMed

Terajima, Masahiko; Taga, Yuki; Cabral, Wayne A; Nagasawa, Masako; Sumida, Noriko; Hattori, Shunji; Marini, Joan C; Yamauchi, Mitsuo

2017-08-04

Cyclophilin B (CypB) is an endoplasmic reticulum-resident protein that regulates collagen folding, and also contributes to prolyl 3-hydroxylation (P3H) and lysine (Lys) hydroxylation of collagen. In this study, we characterized dentin type I collagen in CypB null (KO) mice, a model of recessive osteogenesis imperfecta type IX, and compared to those of wild-type (WT) and heterozygous (Het) mice. Mass spectrometric analysis demonstrated that the extent of P3H in KO collagen was significantly diminished compared to WT/Het. Lys hydroxylation in KO was significantly diminished at the helical cross-linking sites, α1/α2(I) Lys-87 and α1(I) Lys-930, leading to a significant increase in the under-hydroxylated cross-links and a decrease in fully hydroxylated cross-links. The extent of glycosylation of hydroxylysine residues was, except α1(I) Lys-87, generally higher in KO than WT/Het. Some of these molecular phenotypes were distinct from other KO tissues reported previously, indicating the dentin-specific control mechanism through CypB. Histological analysis revealed that the width of predentin was greater and irregular, and collagen fibrils were sparse and significantly smaller in KO than WT/Het. These results indicate a critical role of CypB in dentin matrix formation, suggesting a possible association between recessive osteogenesis imperfecta and dentin defects that have not been clinically detected.

Nanofibrous spongy microspheres enhance odontogenic differentiation of human dental pulp stem cells.

PubMed

Kuang, Rong; Zhang, Zhanpeng; Jin, Xiaobing; Hu, Jiang; Gupte, Melanie J; Ni, Longxing; Ma, Peter X

2015-09-16

Dentin regeneration is challenging due to its complicated anatomical structure and the shortage of odontoblasts. In this study, a novel injectable cell carrier, nanofibrous spongy microspheres (NF-SMS), is developed for dentin regeneration. Biodegradable and biocompatible poly(l-lactic acid)-block-poly(l-lysine) are synthesized and fabricated into NF-SMS using self-assembly and thermally induced phase separation techniques. It is hypothesized that NF-SMS with interconnected pores and nanofibers can enhance the proliferation and odontogenic differentiation of human dental pulp stem cells (hDPSCs), compared to nanofibrous microspheres (NF-MS) without pore structure and conventional solid microspheres (S-MS) with neither nanofibers nor pore structure. During the first 9 d in culture, hDPSCs proliferate significantly faster on NF-SMS than on NF-MS or S-MS (p < 0.05). Following in vitro odontogenic induction, all the examined odontogenic genes (alkaline phosphatase content, osteocalcin, bone sialoprotein, collagen 1, dentin sialophosphoprotein (DSPP)), calcium content, and DSPP protein content are found significantly higher in the NF-SMS group than in the control groups. Furthermore, 6 weeks after subcutaneous injection of hDPSCs and microspheres into nude mice, histological analysis shows that NF-SMS support superior dentin-like tissue formation compared to NF-MS or S-MS. Taken together, NF-SMS have great potential as an injectable cell carrier for dentin regeneration. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mineral induction by immobilized phosphoproteins

NASA Technical Reports Server (NTRS)

Saito, T.; Arsenault, A. L.; Yamauchi, M.; Kuboki, Y.; Crenshaw, M. A.

1997-01-01

Dentin phosphoproteins are thought to have a primary role in the deposition of mineral on the collagen of dentin. In this study we determined the type of binding between collagen and phosphoproteins necessary for mineral formation onto collagen fibrils and whether the phosphate esters are required. Bovine dentin phosphophoryn or phosvitin from egg yolk were immobilized on reconstituted skin type I collagen fibrils by adsorption or by covalent cross-linking. In some samples the ester phosphate was removed from the covalently cross-linked phosphoproteins by treatment with acid phosphatase. All samples were incubated at 37 degrees C in metastable solutions that do not spontaneously precipitate. Reconstituted collagen fibrils alone did not induce mineral formation. The phosphoproteins adsorbed to the collagen fibrils desorbed when the mineralization medium was added, and mineral was not induced. The mineral induced by the cross-linked phosphoproteins was apatite, and the crystals were confined to the surface of the collagen fibrils. With decreasing medium saturation the time required for mineral induction increased. The interfacial tensions calculated for apatite formation by either phosphoprotein cross-linked to collagen were about the same as that for phosphatidic acid liposomes and hydroxyapatite. This similarity in values indicates that the nucleation potential of these highly phosphorylated surfaces is about the same. It is concluded that phosphoproteins must be irreversibly bound to collagen fibrils for the mineralization of the collagen network in solutions that do not spontaneously precipitate. The phosphate esters of phosphoproteins are required for mineral induction, and the carboxylate groups are not sufficient.

Marginal Gap Formation in Approximal "Bulk Fill" Resin Composite Restorations After Artificial Ageing.

PubMed

Peutzfeldt, A; Mühlebach, S; Lussi, A; Flury, S

The aim of this in vitro study was to investigate the marginal gap formation of a packable "regular" resin composite (Filtek Supreme XTE [3M ESPE]) and two flowable "bulk fill" resin composites (Filtek Bulk Fill [3M ESPE] and SDR [DENTSPLY DeTrey]) along the approximal margins of Class II restorations. In each of 39 extracted human molars (n=13 per resin composite), mesial and distal Class II cavities were prepared, placing the gingival margins below the cemento-enamel junction. The cavities were restored with the adhesive system OptiBond FL (Kerr) and one of the three resin composites. After restoration, each molar was cut in half in the oro-vestibular direction between the two restorations, resulting in two specimens per molar. Polyvinylsiloxane impressions were taken and "baseline" replicas were produced. The specimens were then divided into two groups: At the beginning of each month over the course of six months' tap water storage (37°C), one specimen per molar was subjected to mechanical toothbrushing, whereas the other was subjected to thermocycling. After artificial ageing, "final" replicas were produced. Baseline and final replicas were examined under the scanning electron microscope (SEM), and the SEM micrographs were used to determine the percentage of marginal gap formation in enamel or dentin. Paramarginal gaps were registered. The percentages of marginal gap formation were statistically analyzed with a nonparametric analysis of variance followed by Wilcoxon-Mann-Whitney tests and Wilcoxon signed rank tests, and all p-values were corrected with the Bonferroni-Holm adjustment for multiple testing (significance level: α=0.05). Paramarginal gaps were analyzed descriptively. In enamel, significantly lower marginal gap formation was found for Filtek Supreme XTE compared to Filtek Bulk Fill ( p=0.0052) and SDR ( p=0.0289), with no significant difference between Filtek Bulk Fill and SDR ( p=0.4072). In dentin, significantly lower marginal gap formation was found for SDR compared to Filtek Supreme XTE ( p<0.0001) and Filtek Bulk Fill ( p=0.0015), with no significant difference between Filtek Supreme XTE and Filtek Bulk Fill ( p=0.4919). Marginal gap formation in dentin was significantly lower than in enamel ( p<0.0001). The percentage of restorations with paramarginal gaps varied between 0% and 85%, and for all three resin composites the percentages were markedly higher after artificial ageing. The results from this study suggest that in terms of marginal gap formation in enamel, packable resin composites may be superior to flowable "bulk fill" resin composites, while in dentin some flowable "bulk fill" resin composites may be superior to packable ones.

The role of erosion, abrasion and attrition in tooth wear.

PubMed

Barbour, Michele E; Rees, Gareth D

2006-01-01

There is increasing clinical awareness of erosion of enamel and dentine by dietary acids and the consequent increased susceptibility to physical wear. Enamel erosion is characterized by acid-mediated surface softening that, if unchecked, will progress to irreversible loss of surface tissue, potentially exposing the underlying dentine. In comparison, dentine erosion is less well understood as the composition and microstructure are more heterogeneous. Factors which affect the erosive potential of a solution include pH, titratable acidity, common ion concentrations, and frequency and method of exposure. Abrasion and attrition are sources of physical wear and are commonly associated with tooth brushing and tooth-to-tooth contact, respectively. A combination of erosion and abrasion or attrition exacerbates wear; however, further research is required to understand the role of fluoride in protecting mineralized tissues from such processes. Abrasive wear may be seen in a wide range of patients, whereas attritive loss is usually seen in individuals with bruxism. Wear processes are implicated in the development of dentine hypersensitivity. Saliva confers the major protective function against wear due to its role in pellicle formation, buffering, acid clearance, and hard tissue remineralization. This review focuses on the physiochemical factors impacting tooth wear.

Hydrolytic degradation of the resin-dentine interface induced by the simulated pulpal pressure, direct and indirect water ageing.

PubMed

Feitosa, Victor P; Leme, Ariene A; Sauro, Salvatore; Correr-Sobrinho, Lourenço; Watson, Timothy F; Sinhoreti, Mário A; Correr, Américo B

2012-12-01

The aim of this study was to compare the hydrolytic effects induced by simulated pulpal pressure, direct or indirect water exposure within the resin-dentine interfaces created with three "simplified" resin bonding systems (RBSs). A two-step/self-etching (CSE: Clearfil SE Bond), one-step/self-etching (S3: Clearfil S3) and etch-and-rinse/self-priming (SB: Single-bond 2) adhesives were applied onto dentine and submitted to three different prolonged (6 or 12 months) ageing strategies: (i) Simulated Pulpal Pressure (SPP); (ii) Indirect Water Exposure (IWE: intact bonded-teeth); (iii) Direct Water Exposure (DWE: resin-dentine sticks). Control and aged specimens were submitted to microtensile bond strength (μTBS) and nanoleakage evaluation. Water sorption (WS) survey was also performed on resin disks. Results were analysed with two-way ANOVA and Tukey's test (p < 0.05). The μTBS of CS3 and SB dropped significantly (p < 0.05) after 6 months of SPP and DWE. CSE showed a significant μTBS reduction only after 12 months of DWE (p = 0.038). IWE promoted no statistical change in μTBS (p > 0.05) and no evident change in nanoleakage. Conversely, SPP induced a clear formation of "water-trees" in CS3 and SB. WS outcomes were CS3 > SB = CSE. The hydrolytic degradation of resin-dentine interfaces depend upon the type of the in vitro ageing strategy employed in the experimental design. Direct water exposure remains the quickest method to age the resin-dentine bonds. However, the use of SPP may better simulate the in vivo scenario. However, the application of a separate hydrophobic solvent-free adhesive layer may reduce the hydrolytic degradation and increase the longevity of resin-dentine interfaces created with simplified adhesives. Copyright © 2012 Elsevier Ltd. All rights reserved.

Bonding effectiveness and interfacial characterization of a nano-filled resin-modified glass-ionomer.

PubMed

Coutinho, E; Cardoso, M V; De Munck, J; Neves, A A; Van Landuyt, K L; Poitevin, A; Peumans, M; Lambrechts, P; Van Meerbeek, B

2009-11-01

Glass-ionomers (GIs) exhibit excellent clinical bonding effectiveness, but still have shortcomings such as polishability and general aesthetics. The aims of this study were (1) to determine the micro-tensile bond strength (microTBS) to enamel and dentin of a nano-filled resin-modified GI (nano-RMGI; Ketac N100, 3M-ESPE), and (2) to characterize its interfacial interaction with enamel and dentin using transmission electron microscopy (TEM). The nano-RMGI was used both with and without its primer, while a conventional RMGI restorative material (conv-RMGI; Fuji II LC, GC) and a packable conventional GI cement (conv-GI; Fuji IX GP, GC) were used as controls. After bonding to freshly extracted human third molars, microspecimens of the interfaces were machined into a cylindrical hourglass shape and tested to failure in tension. Non-demineralized TEM sections were prepared and examined from additional teeth. The microTBS to both enamel and dentin of nano-RMGI and conv-GI were not statistically different; the microTBS of non-primed nano-RMGI was significantly lower, while that of conv-RMGI was significantly higher than that of all other groups. TEM of nano-RMGI disclosed a tight interface at enamel and dentin without surface demineralization and hybrid-layer formation. A thin filler-free zone (<1 microm) was formed at dentin. A high filler loading and effective filler distribution were also evident, with localized areas exhibiting nano-filler clustering. The nano-RMGI bonded as effectively to enamel and dentin as conv-GI, but bonded less effectively than conv-RMGI. Its bonding mechanism should be attributed to micro-mechanical interlocking provided by the surface roughness, most likely combined with chemical interaction through its acrylic/itaconic acid copolymers.

Evaluation of antibacterial and remineralizing nanocomposite and adhesive in rat tooth cavity model

PubMed Central

Li, Fang; Wang, Ping; Weir, Michael D.; Fouad, Ashraf F.; Xu, Hockin H. K.

2014-01-01

Antibacterial and remineralizing dental composites and adhesives were recently developed to inhibit biofilm acids and combat secondary caries. It is not clear what effect these materials will have on dental pulps in vivo. The objectives of this study were to investigate the antibacterial and remineralizing restorations in a rat tooth cavity model, and determine pulpal inflammatory response and tertiary dentin formation. Nanoparticles of amorphous calcium phosphate (NACP) and antibacterial dimethylaminododecyl methacrylate (DMADDM) were synthesized and incorporated into a composite and an adhesive. Occlusal cavities were prepared in the first molars of rats and restored with four types of restoration: Control composite and adhesive; control plus DMADDM; control plus NACP; and control plus both DMADDM and NACP. At 8 or 30 days (d), rat molars were harvested for histological analysis. For inflammatory cell response, regardless of time periods, NACP group and DMADDM+NACP group showed lower scores (better biocompatibility) than control group (p = 0.014 for 8 d, p = 0.018 for 30 d). For tissue disorganization, NACP and DMADDM+NACP had better scores than control (p = 0.027) at 30 d. At 8 d, restorations containing NACP had tertiary dentin thickness (TDT) that was 5-6 fold that of control. At 30 d, restorations containing NACP had TDT that was 4-6 fold that of control. In conclusion, novel antibacterial and remineralizing restorations were tested in rat teeth in vivo for the first time. Composite and adhesive containing NACP and DMADDM exhibited milder pulpal inflammation and much greater tertiary dentin formation, than control adhesive and composite. Therefore, the novel composite and adhesive containing NACP and DMADDM are promising as a new therapeutic restorative system to not only combat oral pathogens and biofilm acids as shown previously, but also facilitate the healing of the dentin-pulp complex. PMID:24583320

Permanent molar pulpotomy with a new endodontic cement: A case series

PubMed Central

Asgary, Saeed; Ehsani, Sara

2009-01-01

The aim of this case series was to determine the clinical and radiographic success rate of pulpotomy, with new endodontic cement (NEC), in human mature permanent molar teeth. Twelve molars with established irreversible pulpitis were selected from patients 14 – 62 years old. The selection criteria included carious pulp exposure with a positive history of lingering pain. After isolation, caries removal, and pulp exposure, pulpotomy with NEC was performed and a permanent restoration was immediately placed. At the first recall (+1 day) no patients reported postoperative pain. One wisdom tooth had been extracted after two months because of failure in coronal restoration. Eleven patients were available for the second recall, with a mean time of 15.8 months. Clinical and radiographic examination revealed that all teeth were functional and free of signs and symptoms. Histological examination of the extracted teeth revealed complete dentin bridge formation and a normal pulp. Although the results favored the use of NEC, more studies with larger samples and a longer recall period were suggested, to justify the use of this novel material for treatment of irreversible pulpitis in human permanent molar teeth. PMID:20379438

Interfacial micromorphological differences in hybrid layer formation between water- and solvent-based dentin bonding systems.

PubMed

Gregoire, Geneviève L; Akon, Bernadette A; Millas, Arlette

2002-06-01

Many dentin bonding systems of different compositions, and in particular containing different solvents, have been introduced to the market. Their effect on the quality of the interface requires clarification by means of comparative trials. This study investigated micromorphological differences in hybrid layer formation with a variety of commercially available water- or solvent-based dentin bonding products and their recommended compomers. Five bonding systems were used on groups of 10 teeth each as follows: group I, acetone-based system used with 36% phosphoric acid; group II, a different acetone-based system containing nano-sized particles for filler loading and used with a non-rinsing conditioner containing maleic acid; group III, the acetone-based system of group II used with 36% phosphoric acid (the only difference in the treatment for groups II and III was the acid etching system); group IV, a mixed-solvent-based system (water/ethanol) used with 37% phosphoric acid; and group V, a water-based system used with 37% phosphoric acid. Each bonding system was covered with the recommended compomer. Class I occlusal preparations were made in extracted teeth and restored with one of the above systems. Five specimens of each group were studied with optical microscopy after staining. Scanning electron microscopy was used to examine the interface of the bonding system/dentin of the other 5 teeth in each group. The optical microscopy measurements were made with a 10 x 10 reticle. A micron mark with scale was used for the scanning electron microscope. All measurements were made in microm. The following criteria were used to define a good interface: absence of voids between the different parts of the interface, uniformity of the hybrid layer, good opening of the tubuli orifices, and tag adherence to the tubuli walls. Morphological differences were found at the interface depending on dentin treatment and adhesive composition. The acetone-containing systems were associated with a continuous, gap-free hybrid layer that was linked intimately with the dentin. The tags adhered well to the tubuli walls and were often joined by side branches. In the water-based solvent systems, a lack of contact was visible between the resin tags and the tubuli walls, with some incompletely filled tubuli and some gaps in the hybrid layer. The 2 observational methods used, optical and scanning electron microscopy, proved to be complementary. Within the limitations of this study, use of the acetone-based systems after phosphoric acid etching resulted in a continuous, thick hybrid layer with reverse-cone-shaped tags in close contact with the tubuli walls. Use of the water-based systems resulted in a thinner hybrid layer with some incompletely sealed dentinal tubules.

External cervical resorption: an analysis using cone beam and microfocus computed tomography and scanning electron microscopy.

PubMed

Gunst, V; Mavridou, A; Huybrechts, B; Van Gorp, G; Bergmans, L; Lambrechts, P

2013-09-01

To provide a three-dimensional representation of external cervical resorption (ECR) with microscopy, stereo microscopy, cone beam computed tomography (CT), microfocus CT and scanning electron microscopy (SEM). External cervical resorption is an aggressive form of root resorption, leading to a loss of dental hard tissues. This is due to clastic action, activated by a damage of the covering cementum and stimulated probably by infection. Clinically, it is a challenging situation as it is characterized by a late symptomatology. This is due to the pericanalar protection from a resorption-resistant sheet, composed of pre-dentine and surrounding dentine. The clastic activity is often associated with an attempt to repair, seen by the formation of osteoid tissue. Cone beam CT is extremely useful in the diagnoses and treatment planning of ECR. SEM analyses provide a better insight into the activity of osteoclasts. The root canal is surrounded by a layer of dentine that is resistant to resorption. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

A feasible method to eliminate nanoleakage in dentin hybrid layers.

PubMed

Chen, Ji-Hua; Liu, Yan; Niu, Li-Na; Lu, Shuai; Tay, Franklin R; Gao, Yu

2014-10-01

To determine whether high-pressure air blowing during adhesive application affects the infiltration of resin comonomers and nanoleakage manifestation in the resin/dentin interface under simulated pulpal pressure. Thirty mid-coronal dentin surfaces were bonded with an etch-and-rinse adhesive (Adper Single Bond 2) under simulated pulpal pressure. In the control group, the adhesive was thinned by ordinary air blowing with a pressure of 0.2 MPa, while in the experimental group, a high-pressure air blowing technique (pressure: 0.4 MPa) was used. All other procedures followed the manufacturer's instructions. Resin tag formation and nanoleakage in the bonding interface were evaluated with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). When adhesive was thinned with high pressure air blowing, longer and more homogeneous resin tags were formed. The bonding interface demonstrated good overall morphology and integrity. Almost perfect infiltration of resin and no obvious nanoleakage were observed. Thinning of adhesive with high-pressure air blowing provides a clinically feasible adjunctive procedure for better resin infiltration.

Crackling sound generation during the formation of liquid bridges: A lattice gas model

NASA Astrophysics Data System (ADS)

Almeida, Alexandre B.; Buldyrev, Sergey V.; Alencar, Adriano M.

2013-08-01

Due to abnormal mechanical instabilities, liquid bridges may form in the small airways blocking airflow. Liquid bridge ruptures during inhalation are the major cause of the crackling adventitious lung sound, which can be heard using a simple stethoscope. Recently, Vyshedskiy and colleagues (2009) [1] described and characterized a crackle sound originated during expiration. However, the mechanism and origin of the expiratory crackle are still controversial. Thus, in this paper, we propose a mechanism for expiratory crackles. We hypothesize that the expiratory crackle sound is a result of the energy released in the form of acoustic waves during the formation of the liquid bridge. The magnitude of the energy released is proportional to the difference in free energy prior and after the bridge formation. We use a lattice gas model to describe the liquid bridge formation between two parallel planes. Specifically, we determine the surface free energy and the conditions of the liquid bridge formation between two parallel planes separated by a distance 2h by a liquid droplet of volume Ω and contact angle Θ, using both Monte Carlo simulation of a lattice gas model and variational calculus based on minimization of the surface area with the volume and the contact angle constrained. We numerically and analytically determine the phase diagram of the system as a function of the dimensionless parameter hΩ and Θ. We can distinguish two different phases: one droplet and one liquid bridge. We observe a hysteresis curve for the energy changes between these two states, and a finite size effect in the bridge formation. We compute the release of free energy during the formation of the liquid bridge and discuss the results in terms of system size. We also calculate the force exerted from liquid bridge on the planes by studying the dependence of the free energy on the separation between the planes 2h. The simulation results are in agreement with the analytical solution.

Phosphorylation regulates the secondary structure and function of dentin phosphoprotein peptides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Villarreal-Ramirez, Eduardo; Eliezer, David; Garduño-Juarez, Ramon

Dentin phosphoprotein (DPP) is the most acidic protein in vertebrates and structurally is classified as an intrinsically disordered protein. Functionally, DPP is related to dentin and bone formation, however the specifics of such association remain unknown. Here, we used atomistic molecular dynamics simulations to screen selected binding domains of DPP onto hydroxyapatite (HA), which is one of its important interacting partners. From these results, we selected a functionally relevant peptide, Ace-SSDSSDSSDSSDSSD-NH2 (named P5) and its phosphorylated form (named P5P), for experimental characterization. SAXS experiments indicated that in solution P5 was disordered, possibly in an extended conformation while P5P displayed moremore » compact globular conformations. Circular dichroism and FTIR confirmed that, either in the presence or absence of Ca2 +/HA, P5 adopts a random coil structure, whereas its phosphorylated counterpart, P5P, has a more compact arrangement associated with conformations that display β-sheet and α-helix motifs when bound to HA. In solution, P5 inhibited HA crystal growth, whereas at similar concentrations, P5P stimulated it. These findings suggest that phosphorylation controls the transient formation of secondary and tertiary structure of DPP peptides, and, most likely of DPP itself, which in turn controls HA growth in solution and possibly HA growth in mineralized tissues.« less

Fibroblast growth factor-2 regulates the cell function of human dental pulp cells.

PubMed

Shimabukuro, Yoshio; Ueda, Maki; Ozasa, Masao; Anzai, Jun; Takedachi, Masahide; Yanagita, Manabu; Ito, Masako; Hashikawa, Tomoko; Yamada, Satoru; Murakami, Shinya

2009-11-01

Homeostasis and tissue repair of dentin-pulp complex are attributed to dental pulp tissue and several growth factors. Dental pulp cells play a pivotal role in homeostasis of dentin-pulp complex and tissue responses after tooth injury. Among these cytokines, fibroblast growth factor (FGF)-2 has multifunctional biologic activity and is known as a signaling molecule that induces tissue regeneration. In this study, we examined the effects of FGF-2 on growth, migration, and differentiation of human dental pulp cells (HDPC). HDPC were isolated from healthy dental pulp. Cellular response was investigated by [(3)H]-thymidine incorporation into DNA. Cytodifferentiation was examined by alkaline phosphatase (ALPase) assay and cytochemical staining of calcium by using alizarin red. Migratory activity was determined by counting the cells migrating into cleared area that had introduced with silicon block. FGF-2 activated HDPC growth and migration but suppressed ALPase activity and calcified nodule formation. Interestingly, HDPC, which had been pretreated with FGF-2, showed increased ALPase activity and calcified nodule formation when subsequently cultured without FGF-2. These results suggest that FGF-2 potentiates cell growth and accumulation of HDPC that notably did not disturb cytodifferentiation of the cells later. Thus, FGF-2 is a favorable candidate for pulp capping agent. These results provide new evidence for the possible involvement of FGF-2 not only in homeostasis but also in regeneration of dentin-pulp complex.

Heavy metals in human teeth dentine: A bio-indicator of metals exposure and environmental pollution.

PubMed

Asaduzzaman, Khandoker; Khandaker, Mayeen Uddin; Binti Baharudin, Nurul Atiqah; Amin, Yusoff Bin Mohd; Farook, Mohideen Salihu; Bradley, D A; Mahmoud, Okba

2017-06-01

With rapid urbanization and large-scale industrial activities, modern human populations are being increasingly subjected to chronic environmental heavy metal exposures. Elemental uptake in tooth dentine is a bioindicator, the uptake occurring during the formation and mineralization processes, stored to large extent over periods of many years. The uptake includes essential elements, most typically geogenic dietary sources, as well as non-essential elements arising through environmental insults. In this study, with the help of the Dental Faculty of the University of Malaya, a total of 50 separate human teeth were collected from dental patients of various ethnicity, age, gender, occupation, dietary habit, residency, etc. Analysis was conducted using inductively coupled plasma-mass spectrometry (ICP-MS), most samples indicating the presence of the following trace elements, placed in order of concentration, from least to greatest: As, Mn, Ba, Cu, Cr, Pb, Zn, Hg, Sb, Al, Sr, Sn. The concentrations have been observed to increase with age. Among the ethnic groups, the teeth of ethnic Chinese showed marginally greater metal concentrations than those of the Indians and Malays, the teeth dentine of females generally showing greater concentrations than that of males. Greater concentrations of Hg, Cu and Sn were found in molars while Pb, Sr, Sb and Zn were present in greater concentrations in incisors. With the elevated concentration levels of heavy metals in tooth dentine reflecting pollution from industrial emissions and urbanization, it is evident that human tooth dentine can provide chronological information on exposure, representing a reliable bio-indicator of environmental pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

Porcine dentin sialoprotein glycosylation and glycosaminoglycan attachments.

PubMed

Yamakoshi, Yasuo; Nagano, Takatoshi; Hu, Jan Cc; Yamakoshi, Fumiko; Simmer, James P

2011-02-03

Dentin sialophosphoprotein (Dspp) is a multidomain, secreted protein that is critical for the formation of tooth dentin. Mutations in DSPP cause inherited dentin defects categorized as dentin dysplasia type II and dentinogenesis imperfecta type II and type III. Dentin sialoprotein (Dsp), the N-terminal domain of dentin sialophosphoprotein (Dspp), is a highly glycosylated proteoglycan, but little is known about the number, character, and attachment sites of its carbohydrate moieties. To identify its carbohydrate attachment sites we isolated Dsp from developing porcine molars and digested it with endoproteinase Glu-C or pronase, fractionated the digestion products, identified fractions containing glycosylated peptides using a phenol sulfuric acid assay, and characterized the glycopeptides by N-terminal sequencing, amino acid analyses, or LC/MSMS. To determine the average number of sialic acid attachments per N-glycosylation, we digested Dsp with glycopeptidase A, labeled the released N-glycosylations with 2-aminobenzoic acid, and quantified the moles of released glycosylations by comparison to labeled standards of known concentration. Sialic acid was released by sialidase digestion and quantified by measuring β-NADH reduction of pyruvic acid, which was generated stoichiometrically from sialic acid by aldolase. To determine its forms, sialic acid released by sialidase digestion was labeled with 1,2-diamino-4,5-methyleneoxybenzene (DMB) and compared to a DMB-labeled sialic acid reference panel by RP-HPLC. To determine the composition of Dsp glycosaminoglycan (GAG) attachments, we digested Dsp with chondroitinase ABC and compared the chromotagraphic profiles of the released disaccharides to commercial standards. N-glycosylations were identified at Asn37, Asn77, Asn136, Asn155, Asn161, and Asn176. Dsp averages one sialic acid per N-glycosylation, which is always in the form of N-acetylneuraminic acid. O-glycosylations were tentatively assigned at Thr200, Thr216 and Thr316. Porcine Dsp GAG attachments were found at Ser238 and Ser250 and were comprised of chondroitin 6-sulfate and chondroitin 4-sulfate in a ratio of 7 to 3, respectively. The distribution of porcine Dsp posttranslational modifications indicate that porcine Dsp has an N-terminal domain with at least six N-glycosylations and a C-terminal domain with two GAG attachments and at least two O-glycosylations.

Ectopic Hard Tissue Formation by Odonto/Osteogenically In Vitro Differentiated Human Deciduous Teeth Pulp Stem Cells.

PubMed

Kim, Seunghye; Song, Je Seon; Jeon, Mijeong; Shin, Dong Min; Kim, Seong-Oh; Lee, Jae Ho

2015-07-01

There have been many attempts to use the pulp tissue from human deciduous teeth for dentin or bone regeneration. The objective of this study was to determine the effects of odonto/osteogenic in vitro differentiation of deciduous teeth pulp stem cells (DTSCs) on their in vivo hard tissue-forming potential. DTSCs were isolated from extracted deciduous teeth using the outgrowth method. These cells were exposed to odonto/osteogenic stimuli for 4 and 8 days (Day 4 and Day 8 groups, respectively), while cells in the control group were cultured in normal medium. The in vitro differentiated DTSCs and the control DTSCs were transplanted subcutaneously into immunocompromised mice with macroporous biphasic calcium phosphate and sacrificed at 8 weeks post-implantation. The effect of odonto/osteogenic in vitro differentiation was evaluated using alkaline phosphatase (ALP) staining and quantitative reverse transcription polymerase chain reaction (RT-PCR). The in vivo effect was evaluated by qualitative RT-PCR, assessment of ALP activity, histologic analysis, and immunohistochemical staining. The amount of hard tissue was greater in Day 4 group than Day 8 group (p = 0.014). However, Day 8 group generated lamellar bone-like structure, which was immunonegative to anti-human dentin sialoprotein with significantly low expression level of DSPP compared with the control group (p = 0.008). This study demonstrates that odonto/osteogenic in vitro differentiation of DTSCs enhances the formation of bone-like tissue, instead of dentin-like tissue, when transplanted subcutaneously using MBCP as a carrier. The odonto/osteogenic in vitro differentiation of DTSCs may be an effective modification that enhances in vivo bone formation by DTSCs.

CYTOTOXICITY AND BIOCOMPATIBILITY OF DIRECT AND INDIRECT PULP CAPPING MATERIALS

PubMed Central

Modena, Karin Cristina da Silva; Casas-Apayco, Leslie Caroll; Atta, Maria Teresa; Costa, Carlos Alberto de Souza; Hebling, Josimeri; Sipert, Carla Renata; Navarro, Maria Fidela de Lima; Santos, Carlos Ferreira

2009-01-01

There are several studies about the cytotoxic effects of dental materials in contact with the pulp tissue, such as calcium hydroxide (CH), adhesive systems, resin composite and glass ionomer cements. The aim of this review article was to summarize and discuss the cytotoxicity and biocompatibility of materials used for protection of the dentin-pulp complex, some components of resin composites and adhesive systems when placed in direct or indirect contact with the pulp tissue. A large number of dental materials present cytotoxic effects when applied close or directly to the pulp, and the only material that seems to stimulate early pulp repair and dentin hard tissue barrier formation is CH. PMID:20027424

Human treated dentin matrices combined with Zn-doped, Mg-based bioceramic scaffolds and human dental pulp stem cells towards targeted dentin regeneration.

PubMed

Bakopoulou, Athina; Papachristou, Eleni; Bousnaki, Maria; Hadjichristou, Christina; Kontonasaki, Eleana; Theocharidou, Anna; Papadopoulou, Lambrini; Kantiranis, Nikolaos; Zachariadis, George; Leyhausen, Gabriele; Geurtsen, Werner; Koidis, Petros

2016-08-01

This study aimed to investigate the potential of Mg-based bioceramic scaffolds combined with human treated-dentin matrices (hTDMs) and dentinogenesis-related morphogens to promote odontogenic differentiation and dentin-like tissue formation by Dental Pulp Stem Cells-DPSCs. DPSC cultures were established and characterized by flow cytometry. Experimental cavities were prepared inside crowns of extracted teeth and demineralized by EDTA (hTDMs). Zn-doped, Mg-based bioceramic scaffolds, synthesized by the sol-gel technique, were hosted inside the hTDMs. DPSCs were spotted inside the hTDMs/scaffold constructs with/without additional exposure to DMP-1 or BMP-2 (100ng/ml, 24h). Scanning Electron Microscopy-SEM, live/dead fluorescence staining and MTT assay were used to evaluate cell attachment and viability; Real time PCR for expression of osteo/odontogenic markers; Inductively Coupled Plasma-Atomic Emission Spectrometry-ICP/AES for scaffold elemental release analysis; ELISA for hTDM growth factor release analysis; SEM and X-ray Diffraction-XRD for structural/chemical characterization of the regenerated tissues. Scaffolds constantly released low concentrations of Mg(2+), Ca(2+), Zn(2+) and Si(4+), while hTDMs growth factors, like DMP-1, BMP-2 and TGFβ-1. hTDMs/scaffold constructs supported DPSC viability, inducing their rapid odontogenic shift, indicated by upregulation of DSPP, BMP-2, osteocalcin and osterix expression. Newly-formed Ca-P tissue overspread the scaffolds partially transforming into bioapatite. Exposure to DMP-1 or BMP-2 pronouncedly enhanced odontogenic differentiation phenomena. This is the first study to validate that combining the bioactivity and ion releasing properties of bioceramic materials with growth factor release by treated natural dentin further supported by exogenous addition of key dentinogenesis-related morphogens (DMP-1, BMP-2) can be a promising strategy for targeted dentin regeneration. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Chemical interaction of glycero-phosphate dimethacrylate (GPDM) with hydroxyapatite and dentin.

PubMed

Yoshihara, Kumiko; Nagaoka, Noriyuki; Hayakawa, Satoshi; Okihara, Takumi; Yoshida, Yasuhiro; Van Meerbeek, Bart

2018-04-28

Although the functional monomer glycero-phosphate dimethacrylate (GPDM) has since long been used in several dental adhesives and more recently in self-adhesive composite cements and restoratives, its mechanism of chemical adhesion to hydroxyapatite (HAp) is still unknown. We therefore investigated the chemical interaction of GPDM with HAp using diverse chemical analyzers and ultra-structurally characterized the interface of a GPDM-based primer formulation with dentin. HAp particles were added to a GPDM solution for various periods, upon which they were thoroughly washed with ethanol and water prior to being air-dried. As control, 10-methacryloyloxydecyl dihydrogen phosphate (MDP) was used. The molecular interaction of GPDM with HAp was analyzed using X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (NMR) spectroscopy. Crystal formation upon application of GPDM onto dentin was analyzed using thin-film XRD (TF-XRD). Its hydrophobicity was measured using contact-angle measurement. The interaction of GPDM with dentin was characterized using transmission electron microscopy (TEM). XRD revealed the deposition of dicalcium phosphate dihydrate (DCPD: CaHPO 4 ·2H 2 O) on HAp after 24h. NMR confirmed the adsorption of GPDM onto HAp. However, GPDM was easily removed after washing with water, unlike MDP that remained adhered to HAp. Dentin treated with GPDM appeared more hydrophilic compared to dentin treated with MDP. TEM disclosed exposed collagen in the hybrid layer produced by the GPDM-based primer formulation. Although GPDM adsorbed to HAp, it did not form a stable calcium salt. The bond between GPDM and HAp was weak, unlike the strong bond formed by MDP to HAp. Due to its high hydrophilicity, GPDM might be an adequate monomer for an etch-and-rinse adhesive, but appears less appropriate for a 'mild' self-etch adhesive that besides micro-retention ionically interacts with HAp, or for a self-adhesive restorative material. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

The role of protease inhibitors on the remineralization of demineralized dentin using the PILP method.

PubMed

Nurrohman, Hamid; Carneiro, Karina M M; Hellgeth, John; Saeki, Kuniko; Marshall, Sally J; Marshall, Grayson W; Habelitz, Stefan

2017-01-01

Mineralized and sound dentin matrices contain inactive preforms of proteolytic enzymes that may be activated during the demineralization cycle. In this study, we tested the hypothesis that protease inhibitors (PI) preserve demineralized collagen fibrils and other constituents of the dentin matrix and thereby affect the potential for remineralization. Artificial carious lesions with lesion depths of 140 μm were created with acetate buffer (pH = 5.0, 66 hours), and remineralized using a polymer-induced-liquid-precursor (PILP) process (pH = 7.4, 14 days) containing poly(aspartic acid) (pAsp) as the process-directing agent. De- and remineralizing procedures were performed in the presence or absence of PI. Ultrastructure and mechanical recovery of demineralized dentin following PILP remineralization were examined and measured in water with atomic force microscopy (AFM) and nanoindentation. Nanomechanical properties of hydrated artificial lesions had a low elastic modulus (ER <0.4 GPa) extending about 100 μm into the lesion, followed by a sloped region of about 140 μm depth where values reached those of normal dentin (18.0-20.0 GPa). Mapping of mineral content by both micro-FTIR and micro x-ray computed tomography correlated well with modulus profiles obtained by nanoindentation. Tissue demineralized in the presence of PI exhibited higher elastic moduli (average 2.8 GPa) across the lesion and comprised a narrow zone in the outer lesion with strongly increased modulus (up to 8 GPa; p < 0.05), which might be related to the preservation of non-collagenous proteins that appear to induce calcium phosphate mineral formation even under demineralizing physical-chemical conditions. However, mechanical aspects of remineralization through the elastic modulus change, and the micromorphological aspects with SEM and TEM observation were almost identical with PILP treatments being conducted in the presence or absence of PI. Thus, the application of the protease inhibitors (PI) seemed to be less effective in promoting the remineralization of demineralized dentin.

Antibacterial TAP-mimic electrospun polymer scaffold: effects on P. gingivalis-infected dentin biofilm.

PubMed

Albuquerque, Maria Tereza P; Evans, Joshua D; Gregory, Richard L; Valera, Marcia C; Bottino, Marco C

2016-03-01

This study sought to investigate, in vitro, the effects of a recently developed triple antibiotic paste (TAP)-mimic polymer nanofibrous scaffold against Porphyromonas gingivalis-infected dentin biofilm. Dentin specimens (4 × 4 × 1 mm(3)) were prepared from human canines. The specimens were sterilized, inoculated with P. gingivalis (ATCC 33277), and incubated for 1 week to allow for biofilm formation. Infected dentin specimens were exposed for 3 days to the following treatments: antibiotic-free polydioxanone scaffold (PDS, control), PDS + 25 wt% TAP [25 mg of each antibiotic (metronidazole, ciprofloxacin, and minocycline) per mL of the PDS polymer solution], or a saturated TAP-based solution (50 mg of each antibiotic per mL of saline solution). In order to serve as the negative control, infected dentin specimens were left untreated (bacteria only). To determine the antimicrobial efficacy of the TAP-mimic scaffold, a colony-forming unit (CFU) per milliliter (n = 10/group) measurement was performed. Furthermore, additional specimens (n = 2/group) were prepared to qualitatively study biofilm inhibition via scanning electron microscopy (SEM). Statistics were performed, and significance was set at the 5% level. Both the TAP-mimic scaffold and the positive control (TAP solution) led to complete bacterial elimination, differing statistically (p < 0.05) from the negative control group (bacteria only). No statistical differences were observed for CFU per milliliter data between antibiotic-free scaffolds (2.7 log10 CFU/mL) and the negative control (5.9 log10 CFU/mL). The obtained data revealed significant antimicrobial properties of the novel PDS-based TAP-mimic scaffold against an established P. gingivalis-infected dentin biofilm. Collectively, the data suggest that the proposed nanofibrous scaffold might be used as an alternative to the advocated clinical gold standard (i.e., TAP) for intracanal disinfection prior to regenerative endodontics.

Surface roughness and bacterial adhesion on root dentin treated with diode laser and conventional desensitizing agents.

PubMed

Cury, Maiza S; Silva, Camilla B; Nogueira, Ruchele D; Campos, Michelle G D; Palma-Dibb, Regina G; Geraldo-Martins, Vinicius R

2018-02-01

The treatments for dentin hypersensitivity (DH) may change the surface roughness of the root dentin, which can lead to biofilm accumulation, increasing the risk of root caries. The aim was to compare the surface roughness of root dentin after different treatments of DH and the biofilm formation on those surfaces. After initial surface roughness (Sa) assessment, 50 bovine root fragments received the following treatments (n = 10): G 1-no treatment; G2-5% sodium fluoride varnish; G3-professional application of a desensitizing dentifrice; G4-toothbrushing with a desensitizing dentifrice; and G5-diode laser application (908 nm; 1.5 W, 20 s). The Sa was reevaluated after treatments. Afterward, all samples were incubated in a suspension of Streptococcus mutans at 37 °C for 24 h. The colony-forming units (CFU) were counted using a stereoscope, and the results were expressed in CFU/mL. The one-way ANOVA and the Tukey's tests compared the roughness data and the results obtained on the bacterial adhesion test (α = 5%). G2 (2.3 ± 1.67%) showed similar Sa variation than G1 (0.25 ± 0.41%) and G5 (5.69 ± 0.99%), but different from group G3 (9.05 ± 2.39%). Group 4 showed the highest Sa variation (30.02 ± 3.83%; p < 0.05). Bacterial adhesion was higher in G4 (2208 ± 211.9), suggesting that bacterial growth is greater on rougher surfaces. The diode laser and the conventional treatments for DH may change the surface roughness of the root dentin, but only brushing with desensitizing dentifrice induced a higher bacteria accumulation on root dentin surface.

The role of protease inhibitors on the remineralization of demineralized dentin using the PILP method

PubMed Central

Nurrohman, Hamid; Carneiro, Karina M. M.; Hellgeth, John; Saeki, Kuniko; Marshall, Sally J.; Marshall, Grayson W.

2017-01-01

Mineralized and sound dentin matrices contain inactive preforms of proteolytic enzymes that may be activated during the demineralization cycle. In this study, we tested the hypothesis that protease inhibitors (PI) preserve demineralized collagen fibrils and other constituents of the dentin matrix and thereby affect the potential for remineralization. Artificial carious lesions with lesion depths of 140 μm were created with acetate buffer (pH = 5.0, 66 hours), and remineralized using a polymer-induced-liquid-precursor (PILP) process (pH = 7.4, 14 days) containing poly(aspartic acid) (pAsp) as the process-directing agent. De- and remineralizing procedures were performed in the presence or absence of PI. Ultrastructure and mechanical recovery of demineralized dentin following PILP remineralization were examined and measured in water with atomic force microscopy (AFM) and nanoindentation. Nanomechanical properties of hydrated artificial lesions had a low elastic modulus (ER <0.4 GPa) extending about 100 μm into the lesion, followed by a sloped region of about 140 μm depth where values reached those of normal dentin (18.0–20.0 GPa). Mapping of mineral content by both micro-FTIR and micro x-ray computed tomography correlated well with modulus profiles obtained by nanoindentation. Tissue demineralized in the presence of PI exhibited higher elastic moduli (average 2.8 GPa) across the lesion and comprised a narrow zone in the outer lesion with strongly increased modulus (up to 8 GPa; p < 0.05), which might be related to the preservation of non-collagenous proteins that appear to induce calcium phosphate mineral formation even under demineralizing physical-chemical conditions. However, mechanical aspects of remineralization through the elastic modulus change, and the micromorphological aspects with SEM and TEM observation were almost identical with PILP treatments being conducted in the presence or absence of PI. Thus, the application of the protease inhibitors (PI) seemed to be less effective in promoting the remineralization of demineralized dentin. PMID:29182665

Efficacy of different whitening modalities on bovine enamel and dentin.

PubMed

Wiegand, Annette; Vollmer, Doreen; Foitzik, Magdalena; Attin, Rengin; Attin, Thomas

2005-06-01

Previous studies have shown that bleaching treatment may be efficient in both enamel and dentin, but it is still unknown how much the subsurface dentin contributes to the color change of teeth. This in vitro study evaluated the whitening effect of different external bleaching agents on enamel-dentin slabs and subsurface dentin. Ninety bovine teeth were distributed among six groups (A, Opalescence 10%; B, Opalescence PF 15%; C, Opalescence Quick; D, Opalescence Extra Boost; E, Rapid White; F, Whitestrips). Two enamel-dentin specimens were prepared from the labial surface of each teeth. In one of the specimens enamel was removed, resulting in a dentin (CD) disc of 1 mm high. The labial and the pulpal sides of the second specimen were ground until the remaining enamel and dentin layers of the enamel-dentin sample (ED) were 1 mm each. Whitening treatment of the ED specimens was performed according to manufacturers' instructions. Pre- and posttreatment Lab values of ED samples were analyzed using CIE-Lab. Baseline Lab values of dentin were analyzed by evaluation of the CD specimen. Finally, enamel of the ED specimens was removed and color change of the exposed dentin (D) was recorded. For all treatment agents significant color changes (DeltaE) were observed for enamel-dentin samples and subsurface dentin specimens compared to controls. In groups A-D DeltaE was significantly higher in dentin than enamel-dentin. Furthermore, L and b values of bleached enamel-dentin and subsurface dentin samples differed significantly from baseline. Treatment with the tested external whitening bleaching agents resulted in color change of both enamel-dentin and subsurface dentin samples. The results indicate that color change of treated teeth might be highly influenced by color change of the subsurface dentin.

Comparative evaluation of dentinal crack formation after root canal preparation using ProTaper Next, OneShape, and Hyflex EDM

PubMed Central

Das, Sanjib; Pradhan, Prasanti Kumari; Lata, S.; Sinha, Sachidananda Prasad

2018-01-01

Introduction: The purpose of this study was to compare the incidence of dentinal crack formation after root canal preparation using ProTaper Next, OneShape, and Hyflex electrodischarge machining (HEDM). Materials and Methods: A total of 75 extracted mandibular premolars were selected. The root canals were instrumented using ProTaper Next, OneShape, and HEDM rotary files. All roots were horizontally sectioned at 3, 6, and 9 mm from apex with slow-speed saw under water cooling. The sections were observed under a stereomicroscope at ×25 to determine the absence or presence of crack. Data were analyzed using post hoc test and one-way ANOVA. Results: ProTaper Next and HEDM produced significantly less cracks than OneShape. Conclusion: Within the limitation of this in vitro study, it can be concluded that nickel–titanium instruments may cause cracks on the root surface. ProTaper Next and HEDM tend to produce less number of cracks as compared to OneShape. PMID:29674816

Improved reactive nanoparticles to treat dentin hypersensitivity.

PubMed

Toledano-Osorio, Manuel; Osorio, Estrella; Aguilera, Fátima S; Luis Medina-Castillo, Antonio; Toledano, Manuel; Osorio, Raquel

2018-05-01

The aim of this study was to evaluate the effectiveness of different nanoparticles-based solutions for dentin permeability reduction and to determine the viscoelastic performance of cervical dentin after their application. Four experimental nanoparticle solutions based on zinc, calcium or doxycycline-loaded polymeric nanoparticles (NPs) were applied on citric acid etched dentin, to facilitate the occlusion and the reduction of the fluid flow at the dentinal tubules. After 24 h and 7 d of storage, cervical dentin was evaluated for fluid filtration. Field emission scanning electron microscopy, energy dispersive analysis, AFM and Nano-DMA analysis were also performed. Complex, storage, loss modulus and tan delta (δ) were assessed. Doxycycline-loaded NPs impaired tubule occlusion and fluid flow reduction trough dentin. Tubules were 100% occluded in dentin treated with calcium-loaded NPs or zinc-loaded NPs, analyzed at 7 d. Dentin treated with both zinc-NPs and calcium-NPs attained the highest reduction of dentinal fluid flow. Moreover, when treating dentin with zinc-NPs, complex modulus values attained at intertubular and peritubular dentin were higher than those obtained after applying calcium-NPs. Zinc-NPs are then supposed to fasten active dentin remodeling, with increased maturity and high mechanical properties. Zinc-based nanoparticles are then proposed for effective dentin remineralization and tubular occlusion. Further research to finally prove for clinical benefits in patients with dentin hypersensitivity using Zn-doped nanoparticles is encouraged. Erosion from acids provokes dentin hypersensitivity (DH) which presents with intense pain of short duration. Open dentinal tubules and demineralization favor DH. Nanogels based on Ca-nanoparticles and Zn-nanoparticles produced an efficient reduction of fluid flow. Dentinal tubules were filled by precipitation of induced calcium-phosphate deposits. When treating dentin with Zn-nanoparticles, complex modulus values attained at intertubular and peritubular dentin were higher than those obtained after applying Ca-nanoparticles. Zn-nanoparticles are then supposed to fasten active dentin remodeling, with increased maturity and high mechanical properties. Zinc-based nanogels are, therefore, proposed for effective dentin remineralization and tubular occlusion. Further research to finally prove for clinical benefits in patients with dentin hypersensitivity using Zn-doped nanogels is encouraged. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effects of Chemical Cross-linkers on Caries-affected Dentin Bonding

PubMed Central

Macedo, G.V.; Yamauchi, M.; Bedran-Russo, A.K.

2009-01-01

The achievement of a strong and stable bond between composite resin and dentin remains a challenge in restorative dentistry. Over the past two decades, dental materials have been substantially improved, with better handling and bonding characteristics. However, little attention has been paid to the contribution of collagen structure/stability to bond strength. We hypothesized that the induction of cross-linking in dentin collagen improves dentin collagen stability and bond strength. This study investigated the effects of glutaraldehyde- and grape seed extract-induced cross-linking on the dentin bond strengths of sound and caries-affected dentin, and on the stability of dentin collagen. Our results demonstrated that the application of chemical cross-linking agents to etched dentin prior to bonding procedures significantly enhanced the dentin bond strengths of caries-affected and sound dentin. Glutaraldehyde and grape seed extract significantly increased dentin collagen stability in sound and caries-affected dentin, likely via distinct mechanisms. PMID:19892915

The effect of fluoride on enamel and dentin formation in the uremic rat incisor.

PubMed

Lyaruu, Donacian M; Bronckers, Antonius L J J; Santos, Fernando; Mathias, Robert; DenBesten, Pamela

2008-11-01

Renal impairment in children is associated with tooth defects that include enamel pitting and hypoplasia. However, the specific effects of uremia on tooth formation are not known. In this study, we used rat mandibular incisors, which continuously erupt and contain all stages of tooth formation, to characterize the effects of uremia on tooth formation. We also tested the hypothesis that uremia aggravates the fluoride (F)-induced changes in developing teeth. Rats were subjected to a two-stage 5/6 nephrectomy or sham operation and then exposed to 0 (control) or 50 ppm NaF in drinking water for 14 days. The effects of these treatments on food intake, body growth rate, and biochemical serum parameters for renal function and calcium metabolism were monitored. Nephrectomy reduced food intake and weight gain. Intake of F by nephrectomized rats increased plasma F levels twofold and further decreased food intake and body weight gain. Uremia affected formation of dentin and enamel and was more extensive than the effect of F alone. Uremia also significantly increased predentin width and induced deposition of large amounts of osteodentin-like matrix-containing cells in the pulp chamber. In enamel formation, the cells most sensitive to uremia were the transitional-stage ameloblasts. These data demonstrate that intake of F by rats with reduced renal function impairs F clearance from the plasma and aggravates the already negative effects of uremia on incisor tooth development.

Micro-computed Tomography versus the Cross-sectioning Method to Evaluate Dentin Defects Induced by Different Mechanized Instrumentation Techniques.

PubMed

Stringheta, Carolina Pessoa; Pelegrine, Rina Andréa; Kato, Augusto Shoji; Freire, Laila Gonzales; Iglecias, Elaine Faga; Gavini, Giulio; Bueno, Carlos Eduardo da Silveira

2017-12-01

The objective of this study was to compare the methods of micro-computed tomography (micro-CT) and cross-sectioning followed by stereomicroscopy in assessing dentinal defects after instrumentation with different mechanized systems. Forty mesial roots of mandibular molars were scanned and divided into 4 groups (n = 10): Group R, Reciproc; Group PTN, ProTaper Next; Group WOG, WaveOne Gold; Group PDL, ProDesign Logic. After instrumentation, the roots were once again submitted to a micro-CT scan, and then sectioned at 3, 6, and 9 mm from the apex, and assessed for the presence of complete and incomplete dentinal defects under a stereomicroscope. The nonparametric Kruskal-Wallis, Friedman, and Wilcoxon tests were used in the statistical analysis. The study used a significance level of 5%. The total number of defects observed by cross-sectioning followed by stereomicroscopy was significantly higher than that observed by micro-CT, in all of the experimental groups (P ≤ .05). All of the defects identified in the postoperative period were already present in the corresponding preoperative period. There was no significant difference among the instrumentation systems as to the median numbers of defects, for either cross-sectioning followed by stereomicroscopy or micro-CT, at all the root levels (P > .05). In the micro-CT analysis, no significant difference was found between the median numbers of pre- and postinstrumentation defects, regardless of the instrumentation system (P > .05). None of the evaluated instrumentation systems led to the formation of new dentin defects. All of the defects identified in the stereomicroscopic analysis were already present before instrumentation, or were absent at both time points in the micro-CT analysis, indicating that the formation of new defects resulted from the sectioning procedure performed before stereomicroscopy and not from instrumentation. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Fluoride-dependent formation of mineralized layers in bovine dentin during demineralization in vitro.

PubMed

Damen, J J; Buijs, M J; ten Cate, J M

1998-01-01

Demineralization of dentin in the presence of fluoride produces lesions with a mineralized surface layer which becomes thicker and more mineralized with higher fluoride concentrations whereas the lesion depth is hardly affected. The aim of this study was to investigate the effects of the time of fluoride treatment and the amount of fluoride taken up on the properties of the mineralized layer. Discs of bovine dentin embedded in methylmethacrylate with one surface exposed were demineralized in 50 mM acetic acid, 2.2 mM CaCl2, 2.2 mM KH2PO4, pH 5.0. At the start and/or later during the demineralization period, the specimens were incubated individually for 1 or 2 days in 10 ml of the same demineralization solution supplemented with 0.5, 2.0 or 5.0 ppm fluoride, which was then assessed for changes in calcium and fluoride concentrations. After 2, 5 and 8 days, specimens were sectioned for microradiographic analysis so as to follow development of the lesions and the mineralized layers. The results were the following: While demineralization with fluoride present at the first day led to the formation of a surface layer, fluoride present only at a later day produced a subsurface layer, not at the lesion front but closer to the surface. This layer resulted from (re)precipitation and not from preservation of the original mineral. The 'integrated mineral content' of the surface layer increased linearly with the uptake of fluoride, which resulted in an apparent fluorapatite content of about 20 vol%. The profiles of the surface layers remained unchanged during continued demineralization in the absence of fluoride. It was concluded that in the presence of fluoride mineral loss is reduced as a result of the reprecipitation of dissolved mineral ions as a layer of fluoride-enriched apatite. This layer does not offer protection of underlying dentin against continued demineralization.

Effect of curing modes of dual-curing core systems on microtensile bond strength to dentin and formation of an acid-base resistant zone.

PubMed

Li, Na; Takagaki, Tomohiro; Sadr, Alireza; Waidyasekera, Kanchana; Ikeda, Masaomi; Chen, Jihua; Nikaido, Toru; Tagami, Junji

2011-12-01

To evaluate the microtensile bond strength (μTBS) and acid-base resistant zone (ABRZ) of two dualcuring core systems to dentin using four curing modes. Sixty-four caries-free human molars were randomly divided into two groups according to two dual-curing resin core systems: (1) Clearfil DC Core Automix; (2) Estelite Core Quick. For each core system, four different curing modes were applied to the adhesive and core resin: (1) dual-cured and dual-cured (DD); (2) chemically cured and dual-cured (CD); (3) dual-cured and chemically cured (DC); (4) chemically cured and chemically cured (CC). The specimens were sectioned into sticks (n = 20 for each group) for the microtensile bond test. μTBS data were analyzed using two-way ANOVA and the Dunnett T3 test. Failure patterns were examined with scanning electron microscopy (SEM) to determine the proportion of each mode. Dentin sandwiches were produced and subjected to an acid-base challenge. After argon-ion etching, the ultrastructure of ABRZ was observed using SEM. For Clearfil DC Core Automix, the μTBS values in MPa were as follows: DD: 29.1 ± 5.4, CD: 21.6 ± 5.6, DC: 17.9 ± 2.8, CC: 11.5 ± 3.2. For Estelite Core Quick, they were: DD: 48.9 ±5.7, CD: 20.5 ± 4.7, DC: 41.4 ± 8.3, CC: 19.1 ± 6.0. The bond strength was affected by both material and curing mode, and the interaction of the two factors was significant (p < 0.001). Within both systems, there were significant differences among groups, and the DD group showed the highest μTBS (p < 0.05). ABRZ morphology was not affected by curing mode, but it was highly adhesive-material dependent. The curing mode of dual-curing core systems affects bond strength to dentin, but has no significant effect on the formation of ABRZ.

Divergent Resorbability and Effects on Osteoclast Formation of Commonly Used Bone Substitutes in a Human In Vitro-Assay

PubMed Central

Busse, Björn; Schilling, Arndt F.; Schinke, Thorsten; Amling, Michael; Lange, Tobias

2012-01-01

Bioactive bone substitute materials are a valuable alternative to autologous bone transplantations in the repair of skeletal defects. However, clinical studies have reported varying success rates for many commonly used biomaterials. While osteoblasts have traditionally been regarded as key players mediating osseointegration, increasing evidence suggests that bone-resorbing osteoclasts are of crucial importance for the longevity of applied biomaterials. As no standardized data on the resorbability of biomaterials exists, we applied an in vitro-assay to compare ten commonly used bone substitutes. Human peripheral blood mononuclear cells (PBMCs) were differentiated into osteoclasts in the co-presence of dentin chips and biomaterials or dentin alone (control) for a period of 28 days. Osteoclast maturation was monitored on day 0 and 14 by light microscopy, and material-dependent changes in extracellular pH were assessed twice weekly. Mature osteoclasts were quantified using TRAP stainings on day 28 and their resorptive activity was determined on dentin (toluidin blue staining) and biomaterials (scanning electron microscopy, SEM). The analyzed biomaterials caused specific changes in the pH, which were correlated with osteoclast multinuclearity (r = 0.942; p = 0.034) and activity on biomaterials (r = 0.594; p = 0.041). Perossal led to a significant reduction of pH, nuclei per osteoclast and dentin resorption, whereas Tutogen bovine and Tutobone human strikingly increased all three parameters. Furthermore, natural biomaterials were resorbed more rapidly than synthetic biomaterials leading to differential relative resorption coefficients, which indicate whether bone substitutes lead to a balanced resorption or preferential resorption of either the biomaterial or the surrounding bone. Taken together, this study for the first time compares the effects of widely used biomaterials on osteoclast formation and resorbability in an unbiased approach that may now aid in improving the preclinical evaluation of bone substitute materials. PMID:23071629

Effects of water-aging for 6 months on the durability of a novel antimicrobial and protein-repellent dental bonding agent.

PubMed

Zhang, Ning; Zhang, Ke; Weir, Michael D; Xu, David J; Reynolds, Mark A; Bai, Yuxing; Xu, Hockin H K

2018-06-21

Biofilms at the tooth-restoration bonded interface can produce acids and cause recurrent caries. Recurrent caries is a primary reason for restoration failures. The objectives of this study were to synthesize a novel bioactive dental bonding agent containing dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC) to inhibit biofilm formation at the tooth-restoration margin and to investigate the effects of water-aging for 6 months on the dentin bond strength and protein-repellent and antibacterial durability. A protein-repellent agent (MPC) and antibacterial agent (DMAHDM) were added to a Scotchbond multi-purpose (SBMP) primer and adhesive. Specimens were stored in water at 37 °C for 1, 30, 90, or 180 days (d). At the end of each time period, the dentin bond strength and protein-repellent and antibacterial properties were evaluated. Protein attachment onto resin specimens was measured by the micro-bicinchoninic acid approach. A dental plaque microcosm biofilm model was used to test the biofilm response. The SBMP + MPC + DMAHDM group showed no decline in dentin bond strength after water-aging for 6 months, which was significantly higher than that of the control (P < 0.05). The SBMP + MPC + DMAHDM group had protein adhesion that was only 1/20 of that of the SBMP control (P < 0.05). Incorporation of MPC and DMAHDM into SBMP provided a synergistic effect on biofilm reduction. The antibacterial effect and resistance to protein adsorption exhibited no decrease from 1 to 180 d (P > 0.1). In conclusion, a bonding agent with MPC and DMAHDM achieved a durable dentin bond strength and long-term resistance to proteins and oral bacteria. The novel dental bonding agent is promising for applications in preventive and restorative dentistry to reduce biofilm formation at the tooth-restoration margin.

A new Xenacanthiformes shark (Chondrichthyes, Elasmobranchii) from the Late Paleozoic Rio do Rasto Formation (Paraná Basin), Southern Brazil.

PubMed

Pauliv, Victor E; Dias, Eliseu V; Sedor, Fernando A; Ribeiro, Ana Maria

2014-03-01

The Brazilian records on Xenacanthiformes include teeth and cephalic spines from the Parnaíba, Amazonas and Paraná basins. This work describes a new species of Xenacanthidae, collected in an outcrop of Serrinha Member of Rio do Rasto Formation (Wordian to Wuchiapingian), Paraná Basin, municipality of Jacarezinho, State of Paraná. The teeth of the new species are two or three-cuspidated and the aboral surface show a smooth concavity and one rounded basal tubercle. The coronal surface presents one semi-spherical and subcircular coronal button, and also two lateral main cusps and one central (when present) with less than one fifth of the size of the lateral cusps in the labial portion. The lateral cusps are asymmetric or symmetric, rounded in transversal section, lanceolate in longitudinal section, devoid of lateral carinae and lateral serrations, and with few smooth cristae of enameloid. In optical microscope the teeth show a trabecular dentine (osteodentine) base, while the cusps are composed by orthodentine, and the pulp cavities are non-obliterated by trabecular dentine. The fossil assemblage in the same stratigraphical level and in the whole Rio do Rasto Formation indicates another freshwater record for xenacanthid sharks.

MicroCT analysis of a retrieved root restored with a bonded fiber-reinforced composite dowel: a pilot study.

PubMed

Lorenzoni, Fabio Cesar; Bonfante, Estevam A; Bonfante, Gerson; Martins, Leandro M; Witek, Lukasz; Silva, Nelson R F A

2013-08-01

This evaluation aimed to (1) validate micro-computed tomography (microCT) findings using scanning electron microscopy (SEM) imaging, and (2) quantify the volume of voids and the bonded surface area resulting from fiber-reinforced composite (FRC) dowel cementation technique using microCT scanning technology/3D reconstructing software. A fiberglass dowel was cemented in a condemned maxillary lateral incisor prior to its extraction. A microCT scan was performed of the extracted tooth creating a large volume of data in DICOM format. This set of images was imported to image-processing software to inspect the internal architecture of structures. The outer surface and the spatial relationship of dentin, FRC dowel, cement layer, and voids were reconstructed. Three-dimensional spatial architecture of structures and volumetric analysis revealed that 9.89% of the resin cement was composed of voids and that the bonded area between root dentin and cement was 60.63% larger than that between cement and FRC dowel. SEM imaging demonstrated the presence of voids similarly observed using microCT technology (aim 1). MicroCT technology was able to nondestructively measure the volume of voids within the cement layer and the bonded surface area at the root/cement/FRC interfaces (aim 2). The interfaces at the root dentin/cement/dowel represent a timely and relevant topic where several efforts have been conducted in the past few years to understand their inherent features. MicroCT technology combined with 3D reconstruction allows for not only inspecting the internal arrangement rendered by fiberglass adhesively bonded to root dentin, but also estimating the volume of voids and contacted bond area between the dentin and cement layer. © 2013 by the American College of Prosthodontists.

Combined effect of smear layer characteristics and hydrostatic pulpal pressure on dentine bond strength of HEMA-free and HEMA-containing adhesives.

PubMed

Mahdan, Mohd Haidil Akmal; Nakajima, Masatoshi; Foxton, Richard M; Tagami, Junji

2013-10-01

This study evaluated the combined effect of smear layer characteristics with hydrostatic pulpal pressure (PP) on bond strength and nanoleakage expression of HEMA-free and -containing self-etch adhesives. Flat dentine surfaces were obtained from extracted human molars. Smear layers were created by grinding with #180- or #600-SiC paper. Three HEMA-free adhesives (Xeno V, G Bond Plus, Beautibond Multi) and two HEMA-containing adhesives (Bond Force, Tri-S Bond) were applied to the dentine surfaces under hydrostatic PP or none. Dentine bond strengths were determined using the microtensile bond test (μTBS). Data were statistically analyzed using three- and two-way ANOVA with Tukey post hoc comparison test. Nanoleakage evaluation was carried out under a scanning electron microscope (SEM). Coarse smear layer preparation and hydrostatic PP negatively affected the μTBS of HEMA-free and -containing adhesives, but there were no significant differences. The combined experimental condition significantly reduced μTBS of the HEMA-free adhesives, while the HEMA-containing adhesives exhibited no significant differences. Two-way ANOVA indicated that for HEMA-free adhesives, there were significant interactions in μTBS between smear layer characteristics and pulpal pressure, while for HEMA-containing adhesives, there were no significant interactions between them. Nanoleakage formation within the adhesive layers of both adhesive systems distinctly increased in the combined experimental group. The combined effect of coarse smear layer preparation with hydrostatic PP significantly reduced the μTBS of HEMA-free adhesives, while in HEMA-containing adhesives, these effects were not obvious. Smear layer characteristics and hydrostatic PP would additively compromise dentine bonding of self-etch adhesives, especially HEMA-free adhesives. Copyright © 2013 Elsevier Ltd. All rights reserved.

CT evaluation of canal preparation using rotary and hand NI-TI instruments: An in vitro study

PubMed Central

Nagaraja, Shruthi; Sreenivasa Murthy, B V

2010-01-01

Background: Controlled, uniformly tapered radicular preparation is a great challenge in endodontics. Improper preparation can lead to procedural errors like transportation of foramen, uneven dentine thickness, stripping of root canal, formation of ledge, zip, and elbow in curved canals. These procedural errors and their sequel can adversely affect the prognosis of treatment. Aim/Objectives: The present in vitro study aims to evaluate canal preparation based on the following factors: canal transportation, remaining dentine thickness and comparing centering ability between hand Ni-Ti K files and ProTaper rotary Ni-Ti instruments using computed tomography (CT). Materials and Methods: For evaluation, 30 mesiobuccal roots of maxillary molars were selected. Of these, 15 roots were distributed into two groups where Group 1 included hand instrumentation with Ni-Ti K-files; and Group 2 comprised ProTaper NiTi rotary system. Pre instrumentation and post instrumentation three-dimensional CT images were obtained from root cross-sections that were 1 mm thick from apex to the canal orifice; scanned images were then superimposed and compared. Result: It was observed that the manual technique using hand Ni-Ti K-file produced lesser canal transportation and maintained greater dentine thickness than the rotary ProTaper technique at middle and coronal third and this difference was statistically significant. No significant difference was seen with regard to canal transportation and remaining root dentine at apical levels. With regard to centering ratio, no significant difference was seen between both the groups at all levels. Conclusion: ProTaper should be used judiciously, especially in curved canals, as it causes higher canal transportation and thinning of root dentine at middle and coronal levels. None of the groups showed optimal centering ability. PMID:20582214

The effect of root canal preparation on the development of dentin cracks.

PubMed

Milani, Amin Salem; Froughreyhani, Mohammad; Rahimi, Saeed; Jafarabadi, Mohammad Asghari; Paksefat, Sara

2012-01-01

Root fracture is not an instant phenomenon but a result of gradual development of tiny craze lines in tooth structure. Recent studies have shown that canal instrumentation has the potential to cause dentinal cracks. The purpose of this study was to evaluate and compare the formation of dentinal cracks caused by ProTaper rotary system to hand instrumentation. This in vitro study was carried out using 57 mandible incisor teeth. The teeth were decoronated. The roots were then examined to exclude cracked samples. A standard model for PDL simulation was used. The teeth were randomly divided into two experimental and one control group (n=19). The teeth in the experimental groups were prepared using hand or ProTaper Universal rotary instrumentation. The teeth in the control group were left unprepared. The teeth were then sectioned horizontally 3 and 6 mm from the apex, and the number of various dentinal defects was recorded using a dental operating microscope. The differences between groups were analyzed with Fisher's exact test. The hand group demonstrated significantly more defects than the control group (P=0.001). However, there was no significant difference between the rotary compared to the control and hand groups (P>0.05). There was no significant difference between groups with regards to fracture (P>0.05). Other defects including internal, external and surface cracks were more frequent in the hand than in the control or rotary groups (P=0.02), but the difference was not significant between the rotary and control groups (P>0.05). Canal preparation, whether hand or rotary, produces structural defects in dentin. The ProTaper rotary system when used according to the manufacturer's instructions, tends to produce fewer cracks and can be considered a safe preparation technique.

CT evaluation of canal preparation using rotary and hand NI-TI instruments: An in vitro study.

PubMed

Nagaraja, Shruthi; Sreenivasa Murthy, B V

2010-01-01

Controlled, uniformly tapered radicular preparation is a great challenge in endodontics. Improper preparation can lead to procedural errors like transportation of foramen, uneven dentine thickness, stripping of root canal, formation of ledge, zip, and elbow in curved canals. These procedural errors and their sequel can adversely affect the prognosis of treatment. The present in vitro study aims to evaluate canal preparation based on the following factors: canal transportation, remaining dentine thickness and comparing centering ability between hand Ni-Ti K files and ProTaper rotary Ni-Ti instruments using computed tomography (CT). For evaluation, 30 mesiobuccal roots of maxillary molars were selected. Of these, 15 roots were distributed into two groups where Group 1 included hand instrumentation with Ni-Ti K-files; and Group 2 comprised ProTaper NiTi rotary system. Pre instrumentation and post instrumentation three-dimensional CT images were obtained from root cross-sections that were 1 mm thick from apex to the canal orifice; scanned images were then superimposed and compared. It was observed that the manual technique using hand Ni-Ti K-file produced lesser canal transportation and maintained greater dentine thickness than the rotary ProTaper technique at middle and coronal third and this difference was statistically significant. No significant difference was seen with regard to canal transportation and remaining root dentine at apical levels. With regard to centering ratio, no significant difference was seen between both the groups at all levels. ProTaper should be used judiciously, especially in curved canals, as it causes higher canal transportation and thinning of root dentine at middle and coronal levels. None of the groups showed optimal centering ability.

Root length in the permanent teeth of women with an additional X chromosome (47,XXX females).

PubMed

Lähdesmäki, Raija E; Alvesalo, Lassi J

2010-07-01

Previous studies have demonstrated differential effects of the X and Y chromosomes on dental development. The expression of sexual dimorphism in terms of tooth size, shape, number and developmental timing has been explained especially by Y chromosome influence. The Y chromosome promotes enamel, crown and root dentin development. The X chromosome has an effect on enamel deposition. The aim of this research is to study the influence of the extra X chromosome on the development of permanent tooth root length. The study subjects (all of whom were from the Kvantti Dental Research Project) were seven 47,XXX females, five female relatives and 51 and 52 population control men and women, respectively. Measurements were made from panoramic radiographs on available permanent teeth by a digital calliper according to established procedures. The results showed that the maxillary root lengths of the 47,XXX females were of the same magnitude as those in normal women, but the mandibular root lengths were longer in 47,XXX females than in normal men or women. Increased enamel thickness in the teeth of 47,XXX females is apparently caused by the active enamel gene in all X chromosomes having no increased influence on crown dentin formation. These results in 47,XXX females indicate an increase in root dentin development, at least in the mandible, which together with the data on crown formation reflects a continuous long-lasting effect of the X chromosome on dental development.

Comprehensive analyses of how tubule occlusion and advanced glycation end-products diminish strength of aged dentin

NASA Astrophysics Data System (ADS)

Shinno, Yuko; Ishimoto, Takuya; Saito, Mitsuru; Uemura, Reo; Arino, Masumi; Marumo, Keishi; Nakano, Takayoshi; Hayashi, Mikako

2016-01-01

In clinical dentistry, since fracture is a major cause of tooth loss, better understanding of mechanical properties of teeth structures is important. Dentin, the major hard tissue of teeth, has similar composition to bone. In this study, we investigated the mechanical properties of human dentin not only in terms of mineral density but also using structural and quality parameters as recently accepted in evaluating bone strength. Aged crown and root dentin (age ≥ 40) exhibited significantly lower flexural strength and toughness than young dentin (age < 40). Aged dentin, in which the dentinal tubules were occluded with calcified material, recorded the highest mineral density; but showed significantly lower flexural strength than young dentin. Dentin with strong alignment of the c-axis in hydroxyapatite exhibited high fracture strength, possibly because the aligned apatite along the collagen fibrils may reinforce the intertubular dentin. Aged dentin, showing a high advanced glycation end-products (AGEs) level in its collagen, recorded low flexural strength. We first comprehensively identified significant factors, which affected the inferior mechanical properties of aged dentin. The low mechanical strength of aged dentin is caused by the high mineral density resulting from occlusion of dentinal tubules and accumulation of AGEs in dentin collagen.

Longevity of bond strength of resin cements to root dentine after radiation therapy.

PubMed

Yamin, P A; Pereira, R D; Lopes, F C; Queiroz, A M; Oliveira, H F; Saquy, P C; Sousa-Neto, M D

2018-05-04

To evaluate the bond strength and adhesive interface between several resin cements and root dentine immediately and 6 months after radiotherapy. Sixty maxillary canines were selected and randomly assigned to two groups (n = 30): one group was not irradiated and the other one was subjected to a cumulative radiation dose of 60 Gy. The teeth were sectioned to obtain roots 16 mm long and the canals were prepared with the Reciproc system (R50) and filled using a lateral condensation technique with an epoxy resin sealer. Each group was divided into three subgroups (n = 10) according to the resin cement used for fibreglass fibre post cementation: RelyX-U200, Panavia-F2.0 and RelyX ARC. The posts were cemented in accordance with the manufacturer's recommendations. Three 1-mm-thick dentine slices were then obtained from each root third. The first two slices in the crown-apex direction of each third were selected for the push-out test. The failure mode after debonding was determined with a stereo microscope. The third slice from each root third was selected for scanning electron microscopy (SEM) analyses to examine the resin cement-dentine interface with 100, 1000, 2000 and 4000× magnification. Bond strength data were analysed by anova and Tukey's test (α = 0.05). Significantly lower bond strength (P < 0.0001) was obtained after irradiation compared to nonirradiated teeth. RelyX-U200 cemented fibre posts had the higher bond strength (15.17 ± 5.89) compared with RelyX ARC (P < 0.001) and Panavia-F2.0 (P < 0.001). The evaluation after 6 months revealed lower bond strength values compared to the immediate values (P < 0.001) for irradiated and nonirradiated teeth. Cohesive failures occurred in the irradiated dentine. SEM revealed fractures, microfractures and fewer collagen fibres in irradiated root dentine. RelyX-U200 and Panavia-F2.0 were associated with a juxtaposed interface of the cement with the radicular dentine in irradiated and nonirradiated teeth, and for RelyX ARC, hybrid layer formation and tags were observed in both irradiated and nonirradiated teeth. Radiation was associated with a decrease in the push-out bond strength and with lower resin cement/root dentine interface adaptation. Self-adhesive resin cement was a better alternative for fibre post cementation in teeth subjected to radiation therapy. The bond strength decreased after 6 months. © 2018 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Variations in collagen fibrils network structure and surface dehydration of acid demineralized intertubular dentin: effect of dentin depth and air-exposure time.

PubMed

Fawzy, Amr S

2010-01-01

The aim was to characterize the variations in the structure and surface dehydration of acid demineralized intertubular dentin collagen network with the variations in dentin depth and time of air-exposure (3, 6, 9 and 12 min). In addition, to study the effect of these variations on the tensile bond strength (TBS) to dentin. Phosphoric acid demineralized superficial and deep dentin specimens were prepared. The structure of the dentin collagen network was characterized by AFM. The surface dehydration was characterized by probing the nano-scale adhesion force (F(ad)) between AFM tip and intertubular dentin surface as a new experimental approach. The TBS to dentin was evaluated using an alcohol-based dentin self-priming adhesive. AFM images revealed a demineralized open collagen network structure in both of superficial and deep dentin at 3 and 6 min of air-exposure. However, at 9 min, superficial dentin showed more collapsed network structure compared to deep dentin that partially preserved the open network structure. Total collapsed structure was found at 12 min for both of superficial and deep dentin. The value of the F(ad) is decreased with increasing the time of air-exposure and is increased with dentin depth at the same time of air-exposure. The TBS was higher for superficial dentin at 3 and 6 min, however, no difference was found at 9 and 12 min. The ability of the demineralized dentin collagen network to resist air-dehydration and to preserve the integrity of open network structure with the increase in air-exposure time is increased with dentin depth. Although superficial dentin achieves higher bond strength values, the difference in the bond strength is decreased by increasing the time of air-exposure. The AFM probed F(ad) showed to be sensitive approach to characterize surface dehydration, however, further researches are recommended regarding the validity of such approach.

Concept and clinical application of the resin-coating technique for indirect restorations.

PubMed

Nikaido, Toru; Tagami, Junji; Yatani, Hirofumi; Ohkubo, Chikahiro; Nihei, Tomotaro; Koizumi, Hiroyasu; Maseki, Toshio; Nishiyama, Yuichiro; Takigawa, Tomoyoshi; Tsubota, Yuji

2018-03-30

The resin-coating technique is one of the successful bonding techniques used for the indirect restorations. The dentin surfaces exposed after cavity preparation are coated with a thin film of a coating material or a dentin bonding system combined with a flowable composite resin. Resin coating can minimize pulp irritation and improve the bond strength between a resin cement and tooth structures. The technique can also be applied to endodontically treated teeth, resulting in prevention of coronal leakage of the restorations. Application of a resin coating to root surface provides the additional benefit of preventing root caries in elderly patients. Therefore, the coating materials have the potential to reinforce sound tooth ("Super Tooth" formation), leading to preservation of maximum tooth structures.

Effectiveness of various toothpastes on dentine tubule occlusion.

PubMed

Arnold, W H; Prange, M; Naumova, E A

2015-04-01

Dentine hypersensitivity is an increasing problem in dentistry. Several products are available that claim to occlude open dentine tubules and to reduce dentine hypersensitivity. The aim of this study was to investigate the effectiveness of several different products on dentine tubule occlusion using qualitative and quantitative methods. Dentine discs were prepared from extracted human premolars and molars. The dentine discs were brushed with 6 different experimental toothpastes, 1 positive control toothpaste and 1 negative control without toothpaste; the brushing simulated a total brushing time of 1 year. Half of the discs were etched with lemon juice after toothpaste application. Standardized scanning electron microphotographs were taken and converted into binary black and white images. The black pixels, which represented the open dentine tubules, were counted and statistically evaluated. Then, half of the dentine discs were broken, and the occlusion of the dentine tubules was investigated using energy dispersive X-ray spectroscopy (EDS). The number of open dentine tubules decreased significantly after brushing with 5 of the 6 tested toothpastes. A significant effect was observed after acid erosion for 3 of the 6 tested toothpastes. EDS revealed partly closed dentine tubules after brushing with 3 toothpastes; however, no partly closed dentine tubules were observed after acid erosion. Some toothpastes are capable of partial dentine tubule occlusion. This occlusion is unstable and can be removed with acid erosion. Desensitizing toothpastes are the most common products that are used against dentine hypersensitivity, and these toothpastes affect dentine tubule occlusion. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Porcine dentin sialoprotein glycosylation and glycosaminoglycan attachments

PubMed Central

2011-01-01

Background Dentin sialophosphoprotein (Dspp) is a multidomain, secreted protein that is critical for the formation of tooth dentin. Mutations in DSPP cause inherited dentin defects categorized as dentin dysplasia type II and dentinogenesis imperfecta type II and type III. Dentin sialoprotein (Dsp), the N-terminal domain of dentin sialophosphoprotein (Dspp), is a highly glycosylated proteoglycan, but little is known about the number, character, and attachment sites of its carbohydrate moieties. Results To identify its carbohydrate attachment sites we isolated Dsp from developing porcine molars and digested it with endoproteinase Glu-C or pronase, fractionated the digestion products, identified fractions containing glycosylated peptides using a phenol sulfuric acid assay, and characterized the glycopeptides by N-terminal sequencing, amino acid analyses, or LC/MSMS. To determine the average number of sialic acid attachments per N-glycosylation, we digested Dsp with glycopeptidase A, labeled the released N-glycosylations with 2-aminobenzoic acid, and quantified the moles of released glycosylations by comparison to labeled standards of known concentration. Sialic acid was released by sialidase digestion and quantified by measuring β-NADH reduction of pyruvic acid, which was generated stoichiometrically from sialic acid by aldolase. To determine its forms, sialic acid released by sialidase digestion was labeled with 1,2-diamino-4,5-methyleneoxybenzene (DMB) and compared to a DMB-labeled sialic acid reference panel by RP-HPLC. To determine the composition of Dsp glycosaminoglycan (GAG) attachments, we digested Dsp with chondroitinase ABC and compared the chromotagraphic profiles of the released disaccharides to commercial standards. N-glycosylations were identified at Asn37, Asn77, Asn136, Asn155, Asn161, and Asn176. Dsp averages one sialic acid per N-glycosylation, which is always in the form of N-acetylneuraminic acid. O-glycosylations were tentatively assigned at Thr200, Thr216 and Thr316. Porcine Dsp GAG attachments were found at Ser238 and Ser250 and were comprised of chondroitin 6-sulfate and chondroitin 4-sulfate in a ratio of 7 to 3, respectively. Conclusions The distribution of porcine Dsp posttranslational modifications indicate that porcine Dsp has an N-terminal domain with at least six N-glycosylations and a C-terminal domain with two GAG attachments and at least two O-glycosylations. PMID:21291557

Morphological and chemical characterization of the dentin/resin cement interface produced with a self-etching primer.

PubMed

Walker, Mary P; Wang, Yong; Spencer, Paulette

2002-01-01

The purpose of this study was to analyze a resin cement/dentin interface by comparing the diffusion of a resin cement into dentin surfaces pretreated with a self-etching primer with or without pretreatment by conventional acid etching. Dentin surfaces of 8 unerupted human third molars were treated with a self-etch primer (Panavia 21) with or without conventional phosphoric acid pretreatment. Panavia 21 resin cement was applied according to manufacturer's instructions. Dentin/resin cement interface sections from each tooth were examined with scanning electron microscopy and micro-Raman spectroscopy. When the self-etch primer was used following conventional acid pretreatment, the resin cement did not penetrate to the depth of the zone of demineralized dentin, leaving a substantial area of exposed dentin matrix at the dentin/cement interface. In contrast, there was substantial resin cement diffusion throughout the demineralized dentin when the self-etch primer was used without acid etching pretreatment. The in vitro evaluation of resin cement penetration throughout the zone of demineralized dentin is an important step in identifying sites of exposed dentin matrix that may promote postoperative sensitivity and may leave the dentin/resin cement interface vulnerable to premature degradation under clinical conditions. In this study, the self-etch primer used alone produced substantial resin cement penetration and left no exposed dentin matrix at the dentin/resin cement interface.

Expression of transcripts for fibroblast growth factor 18 and its possible receptors during postnatal dentin formation in rat molars.

PubMed

Baba, Otto; Ota, Masato S; Terashima, Tatsuo; Tabata, Makoto J; Takano, Yoshiro

2015-05-01

Fibroblast growth factors (FGFs) regulate the proliferation and differentiation of various cells via their respective receptors (FGFRs). During the early stages of tooth development in fetal mice, FGFs and FGFRs have been shown to be expressed in dental epithelia and mesenchymal cells at the initial stages of odontogenesis and to regulate cell proliferation and differentiation. However, little is known about the expression patterns of FGFs in the advanced stages of tooth development. In the present study, we focused on FGF18 expression in the rat mandibular first molar (M1) during the postnatal crown and root formation stages. FGF18 signals by RT-PCR using cDNAs from M1 were very weak at postnatal day 5 and were significantly up-regulated at days 7, 9 and 15. Transcripts were undetectable by in situ hybridization (ISH) but could be detected by in situ RT-PCR in the differentiated odontoblasts and cells of the sub-odontoblastic layer in both crown and root portions of M1 at day 15. The transcripts of FGFR2c and FGFR3, possible candidate receptors of FGF18, were detected by RT-PCR and ISH in differentiated odontoblasts throughout postnatal development. These results suggest the continual involvement of FGF18 signaling in the regulation of odontoblasts during root formation where it may contribute to dentin matrix formation and/or mineralization.

Different methods of dentin processing for application in bone tissue engineering: A systematic review.

PubMed

Tabatabaei, Fahimeh Sadat; Tatari, Saeed; Samadi, Ramin; Moharamzadeh, Keyvan

2016-10-01

Dentin has become an interesting potential biomaterial for tissue engineering of oral hard tissues. It can be used as a scaffold or as a source of growth factors in bone tissue engineering. Different forms of dentin have been studied for their potential use as bone substitutes. Here, we systematically review different methods of dentin preparation and the efficacy of processed dentin in bone tissue engineering. An electronic search was carried out in PubMed and Scopus databases for articles published from 2000 to 2016. Studies on dentin preparation for application in bone tissue engineering were selected. The initial search yielded a total of 1045 articles, of which 37 were finally selected. Review of studies showed that demineralization was the most commonly used dentin preparation process for use in tissue engineering. Dentin extract, dentin particles (tooth ash), freeze-dried dentin, and denatured dentin are others method of dentin preparation. Based on our literature review, we can conclude that preparation procedure and the size and shape of dentin particles play an important role in its osteoinductive and osteoconductive properties. Standardization of these methods is important to draw a conclusion in this regard. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2616-2627, 2016. © 2016 Wiley Periodicals, Inc.

Anti-proteolytic capacity and bonding durability of proanthocyanidin-biomodified demineralized dentin matrix

PubMed Central

Liu, Rui-Rui; Fang, Ming; Zhang, Ling; Tang, Cheng-Fang; Dou, Qi; Chen, Ji-Hua

2014-01-01

Our previous studies showed that biomodification of demineralized dentin collagen with proanthocyanidin (PA) for a clinically practical duration improves the mechanical properties of the dentin matrix and the immediate resin–dentin bond strength. The present study sought to evaluate the ability of PA biomodification to reduce collagenase-induced biodegradation of demineralized dentin matrix and dentin/adhesive interfaces in a clinically relevant manner. The effects of collagenolytic and gelatinolytic activity on PA-biomodified demineralized dentin matrix were analysed by hydroxyproline assay and gelatin zymography. Then, resin-/dentin-bonded specimens were prepared and challenged with bacterial collagenases. Dentin treated with 2% chlorhexidine and untreated dentin were used as a positive and negative control, respectively. Collagen biodegradation, the microtensile bond strengths of bonded specimens and the micromorphologies of the fractured interfaces were assessed. The results revealed that both collagenolytic and gelatinolytic activity on demineralized dentin were notably inhibited in the PA-biomodified groups, irrespective of PA concentration and biomodification duration. When challenged with exogenous collagenases, PA-biomodified bonded specimens exhibited significantly less biodegradation and maintained higher bond strengths than the untreated control. These results suggest that PA biomodification was effective at inhibiting proteolytic activity on demineralized dentin matrix and at stabilizing the adhesive/dentin interface against enzymatic degradation, is a new concept that has the potential to improve bonding durability. PMID:24810807

Nanoleakage of dentin adhesive systems bonded to Carisolv-treated dentin.

PubMed

Kubo, Shisei; Li, Heping; Burrow, Michael F; Tyas, Martin J

2002-01-01

The hybrid layer created in caries-affected dentin has not been fully elucidated and may influence bond durability. This study investigated the nanoleakage patterns of caries-affected dentin after excavation with Carisolv or conventional instruments treated with one of three adhesive systems. Flat occlusal dentin surfaces, including carious lesions, were prepared from extracted human molars and finished with wet 600-grit silicon carbide paper. Carious dentin was removed with Carisolv or round steel burs in conjunction with Caries Detector. PermaQuik, Single Bond or One-Up Bond F was bonded to the excavated dentin surfaces and adjacent flat occlusal surfaces and it was covered with Silux Plus resin-based composite. After 24-hour storage in 37 degrees C water, the bonded interfaces were polished to remove flash, and the surrounding tooth surfaces were coated with nail varnish. Specimens were immersed in 50% (w/v) silver nitrate solution for 24 hours, exposed to photo developing solution for eight hours, then sectioned longitudinally through the bonded, excavated dentin or "normal" dentin surfaces. The sectioned surfaces were polished, carbon coated and observed in a Field Emission-SEM using back scattered electrons. Silver deposition occurred along the base of the hybrid layer for all specimens. However, Single Bond showed a greater density of silver deposition in the caries-affected dentin compared with normal dentin. PermaQuik had a thicker hybrid layer in caries-affected dentin than normal dentin. One-Up Bond F exhibited a thin hybrid layer in normal dentin, but the hybrid layer was often difficult to detect in caries-affected dentin.

Dentin hypersensitivity: from diagnosis to a breakthrough therapy for everyday sensitivity relief.

PubMed

Cummins, Diane

2009-01-01

This paper provides an overview of the current knowledge of diagnosis, epidemiology, etiology, and clinical management of dentin hypersensitivity. It summarizes technical approaches to relieve sensitivity in professional and home-use products, with emphasis on the clinical evidence for the efficacy of desensitizing toothpaste, and introduces a new innovative dentifrice technology containing 8% arginine, calcium carbonate, and 1450 ppm fluoride. Dentin hypersensitivity is characterized by short, sharp pain arising from exposed dentin in response to external stimuli which cannot be ascribed to any other form of dental defect or disease. The hydrodynamic theory proposes that pain-producing stimuli cause a change in dentin fluid flow that activates intra-dental nerve fibers, via a mechanoreceptor response, to cause pain. To be hypersensitive, dentin must be exposed and dentin tubules must be open to external stimuli and patent at the pulp. Gingival recession is the primary cause of dentin exposure, and a major predisposing factor for dentin hypersensitivity. Dentin hypersensitivity is a prevalent condition. It has been reported to afflict 15-20% of the adult population, typically 20 to 50-year-olds, with peak incidence between 30 and 39 years. Some studies have reported higher prevalence levels of up to 57%. The incidence of dentin hypersensitivity is expected to rise with changing diets, and as caries and periodontal disease prevention result in improved oral health status, and retention and functionality of the dentition. Treatments to relieve dentin hypersensitivity are based on interruption of the neural response to pain stimuli or occlusion of open tubules to block the hydrodynamic mechanism. Effective and robust dentin occlusion offers the greatest prospect for instant and lasting relief of dentin hypersensitivity. In particular, materials which can coat exposed dentin surfaces, in addition to plugging and sealing open dentin tubules, offer the intriguing prospect of strengthening dentin and rendering it less susceptible to predisposing factors, while concurrently reducing dentin hypersensitivity. Clinical studies have shown that a new toothpaste containing 8% arginine, calcium carbonate, and 1450 ppm fluoride as sodium monofluorophosphate offers significantly increased efficacy in reducing sensitivity, compared to a market-leading toothpaste containing 2% potassium ion. Mechanism of action studies have shown that this technology physically seals dentin tubules with a plug that contains arginine, calcium carbonate, and phosphate. This plug, which is resistant to normal pulpal pressures and to acid challenge, effectively reduces dentin fluid flow and, thereby, reduces sensitivity.

The threshold effects of Nd and Ho: YAG laser-induced surface modification on demineralization of dentin surfaces.

PubMed

Kinney, J H; Haupt, D L; Balooch, M; White, J M; Bell, W L; Marshall, S J; Marshall, G W

1996-06-01

Laser irradiation alters the structure of dentin and produces surface layers that give the appearance of being more enamel-like. The laser-modified surface may be more resistant to demineralization; hence, many investigators are proposing continued development of the laser as a possible preventive treatment for caries. The purpose of this study was to explore the morphological changes that occur in dentin when treated at threshold illuminance with two clinically interesting laser wavelengths, and to evaluate the effectiveness of the laser-treated surface at resisting demineralization in an acid-gel solution. The Nd: YAG laser (wavelength 1060 nm) produced significant recrystallization and grain growth of the apatite, without the formation of second phases such as beta-tricalcium phosphate. This recrystallized surface layer showed resistance to demineralization; however, the layer did not provide protection of the underlying dentin from demineralization because of cracks and macroscopic voids that allowed for penetration of the demineralizing gel. The Ho: YAG laser-treated surface (wavelength 2100 nm) did not show significant evidence of recrystallization and grain growth, and only a trace amount of an acid-resistant layer was observed with demineralization. It is speculated that the Ho:YAG laser is coupling with absorbed water, and that the heat transfer from the water to the mineral phase is inefficient. For the purposes of creating a demineralization-resistant layer, threshold illuminance with both Nd: YAG and Ho: YAG was ineffective.

Chlorhexidine binding to mineralized versus demineralized dentin powder

PubMed Central

Kim, Jongryul; Uchiyama, Toshikazu; Carrilho, Marcela; Agee, Kelli A.; Mazzoni, Annalisa; Breschi, Lorenzo; Carvalho, Ricardo M.; Tjäderhane, Leo; Looney, Stephen; Wimmer, Courtney; Tezvergil-Mutluay, Arzu; Tay, Franklin R.; Pashley, David H.

2010-01-01

Objectives The purposes of this work were to quantitate the affinity and binding capacity of chlorhexidine (CHX) digluconate to mineralized vs. demineralized dentin powder, and to determine how much debinding would result from rinsing with water, ethanol, hydroxyethylmethacrylate (HEMA) or 0.5 M NaCl in water. Methods Dentin powder was made from coronal dentin of extracted human third molars. Standard amounts of dentin powder were tumbled with increasing concentrations of CHX (0–30 mM) for 30 min at 37 C. After centrifuging the tubes, the supernatant was removed and the decrease in CHX concentration quantitated by UV-spectroscopy. CHX-treated dentin powder was resuspended in one of the four debinding solutions for 3 min. The amount of debound CHX in the solvents was also quantitated by UV-spectroscopy. Results As the CHX concentration in the medium increased, the CHX binding to mineralized dentin powder also increased up to 6.8 μmoles/g of dry dentin powder. Demineralized dentin powder took up significantly (p<0.01) more CHX, reaching 30.1 μmoles CHX/g of dry dentin powder. Debinding of CHX was in the order: HEMA < ethanol < 0.05 M NaCl < water. The highest CHX binding to demineralized dentin occurred at 30 mM (1.5 wt%). Significance As CHX is not debound by HEMA, it may remain bound to demineralized dentin during resin-dentin bonding. This may be responsible for the long-term efficacy of CHX as an MMP inhibitor in resin-dentin bonds. PMID:20472280

In vivo remineralization of dentin using an agarose hydrogel biomimetic mineralization system

NASA Astrophysics Data System (ADS)

Han, Min; Li, Quan-Li; Cao, Ying; Fang, Hui; Xia, Rong; Zhang, Zhi-Hong

2017-02-01

A novel agarose hydrogel biomimetic mineralization system loaded with calcium and phosphate was used to remineralize dentin and induce the oriented densely parallel packed HA layer on defective dentin surface in vivo in a rabbit model. Firstly, the enamel of the labial surface of rabbits’ incisor was removed and the dentin was exposed to oral environment. Secondly, the hydrogel biomimetic mineralization system was applied to the exposed dentin surface by using a custom tray. Finally, the teeth were extracted and evaluated by scanning electron microscopy, X-ray diffraction, and nanoindentation test after a certain time of mineralization intervals. The regenerated tissue on the dentin surface was composed of highly organised HA crystals. Densely packed along the c axis, these newly precipitated HA crystals were perpendicular to the underlying dental surface with a tight bond. The demineralized dentin was remineralized and dentinal tubules were occluded by the grown HA crystals. The nanohardness and elastic modulus of the regenerated tissue were similar to natural dentin. The results indicated a potential clinical use for repairing dentin-exposed related diseases, such as erosion, wear, and dentin hypersensitivity.

Effect of Dimethyl Sulfoxide on Bond Strength of a Self-Etch Primer and an Etch and Rinse Adhesive to Surface and Deep Dentin.

PubMed

Sharafeddin, Farahnaz; Salehi, Raha; Feizi, Negar

2016-09-01

Composite bond to dentin is crucial in many clinical conditions particularly in deep cavities without enamel margins due to insufficient penetration of adhesive into demineralized dentin. The aim of this study was to assess the shear bond strength (SBS) of a methacrylate-based and a silorane-based composite resin to surface and deep dentin after pretreatment with dimethyl sulfoxide (DMSO). Eighty extracted human premolars were randomly divided into two groups of flat occlusal dentin with different cuts as A: surface group (sections just below the dentinoenamel junction (DEJ) and B: deep group (2 mm below DEJ). Each group was randomly assigned to 4 subgroups and their samples were restored with Adper Single bond (ASB) and Filtek Z350 or Silorane system Adhesive (SA) and Filtek P90 composite resins, using a 3×3mm cylindrical plastic mold. following these steps , the subgroups were assigned as SubgroupA 1 : surface dentin+ Silorane System Primer (SSP)+ Silorane System Bonding (SSB)+ P90; Subgroup A 2 : surface dentin+ 37% etchant (E37%) + Adper Single Bond (ASB)+ Z350; Subgroup A 3 : surface dentin+ DMSO+ SSP+ SSB+ P90; Subgroup A 4 : surface dentin+ E37%+ DMSO+ ASB+ Z350; Subgroup B 1 : deep dentin+ SSP+ SSB+ P90; Subgroup B 2 : deep dentin+ E37%+ ASB+ Z350; Subgroup B 3 : deep dentin+ DMSO+ SSP+ SSB+ P90; Subgroup B 4 :dentin +E37% +DMSO +ASB +Z350. The specimens were thermocycled at 5± 2/55± 2°C for 1000 cycles and then tested for SBS. Using DMSO as dentin conditioner increased SBS of ASB to deep dentin (p< 0.001) and SBS of SA to surface dentin (p= 0.003) but had no effect on SBS of SA to deep dentin (p= 1.00). The ability of DMSO to increase SBS of ASB to deep dentin provides a basis for improving bonding of this composite resin in deep cavities.

Effect of reciprocating file motion on microcrack formation in root canals: an SEM study.

PubMed

Ashwinkumar, V; Krithikadatta, J; Surendran, S; Velmurugan, N

2014-07-01

To compare dentinal microcrack formation whilst using Ni-Ti hand K-files, ProTaper hand and rotary files and the WaveOne reciprocating file. One hundred and fifty mandibular first molars were selected. Thirty teeth were left unprepared and served as controls, and the remaining 120 teeth were divided into four groups. Ni-Ti hand K-files, ProTaper hand files, ProTaper rotary files and WaveOne Primary reciprocating files were used to prepare the mesial canals. Roots were then sectioned 3, 6 and 9 mm from the apex, and the cut surface was observed under scanning electron microscope (SEM) and checked for the presence of dentinal microcracks. The control and Ni-Ti hand K-files groups were not associated with microcracks. In roots prepared with ProTaper hand files, ProTaper rotary files and WaveOne Primary reciprocating files, dentinal microcracks were present. There was a significant difference between control/Ni-Ti hand K-files group and ProTaper hand files/ProTaper rotary files/WaveOne Primary reciprocating file group (P < 0.001) with ProTaper rotary files producing the most microcracks. No significant difference was observed between teeth prepared with ProTaper hand files and WaveOne Primary reciprocating files. ProTaper rotary files were associated with significantly more microcracks than ProTaper hand files and WaveOne Primary reciprocating files. Ni-Ti hand K-files did not produce microcracks at any levels inside the root canals. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Effect of Different Torque Settings on Crack Formation in Root Dentin.

PubMed

Dane, Asım; Capar, Ismail Davut; Arslan, Hakan; Akçay, Merve; Uysal, Banu

2016-02-01

The aim of the present study was to observe the incidence of cracks in root canal dentin using the ProTaper Universal system (Dentsply Maillefer, Ballaigues, Switzerland) at low- and high-torque settings. Sixty-nine mandibular premolar teeth that had been extracted for different reasons were selected. The teeth were divided into 3 groups: an unprepared control group, a low-torque settings group (SX = 3, S1 = 2, S2 = 1, F1 = 1.5, F2 = 2, F3 = 2, F4 = 2 N/cm), and a high-torque settings group (SX = 4, S1 = 4, S2 = 1.5, F1 = 2, F2 = 3, F3 = 3, F4 = 3 N/cm). After a root canal procedure, all the teeth were horizontally sectioned at 2, 4, 6, and 8 mm from the apex. Then, under a stereomicroscope, all the slices were examined to determine the presence of cracks. A chi-square test was used for data analysis. The significance level was set at P = .05. There were no cracks in the unprepared control group. Vertical root fractures were not observed in any of the groups. There were significantly fewer cracks (17.4% of the sections) in the low-torque group than in the high-torque group (29.4% of the sections) (P < .05). In this in vitro study, the instrumentation of root canals with the ProTaper Universal instrument caused more crack formation in root canal dentin at high-torque than at low-torque settings. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

An in vitro assessment of the effect of load and pH on wear between opposing enamel and dentine surfaces.

PubMed

Ranjitkar, Sarbin; Kaidonis, John A; Townsend, Grant C; Vu, Anh M; Richards, Lindsay C

2008-11-01

Previous in vitro studies have described the wear characteristics of specimens in which enamel has been opposed to enamel and dentine opposed to dentine. The aim of this study was to assess the characteristics of wear between specimens in which enamel was opposed to dentine at loads simulating attrition and at pH values simulating different erosive environments. It was hypothesized that enamel would wear more slowly than dentine under all conditions. Opposing enamel and dentine specimens from 57 human third molar teeth were worn in electromechanical machines with various loads (32, 62 and 100 N) and lubricants (pH 1.2, 3.0 and 6.1). Tooth wear was quantified by measuring reduction in dentine volume over time using a 3D profilometer. Qualitative assessment was also carried out using scanning electron microscopy. Dentine wear increased with increasing load, and dentine wear was faster at pH 1.2 than at pH 3.0 or 6.1 for all loads tested. Interestingly, enamel wore more rapidly than dentine at pH 1.2 under all loads. At pH values of 3.0 and 6.1, enamel wear rates were not measurably different from zero and they were less than wear rates for opposing dentine specimens at all loads. Micrographic assessment showed extensive surface destruction of dentine wear facets due to erosion at pH 1.2. Dentine wear facets were smoother at pH 3.0 that at pH 6.1. When enamel wears against dentine in an acidic environment enamel will wear more rapidly at very low pH, while under less acid conditions dentine will wear faster than enamel.

Effect of dimethyl sulfoxide on dentin collagen.

PubMed

Mehtälä, P; Pashley, D H; Tjäderhane, L

2017-08-01

Infiltration of adhesive on dentin matrix depends on interaction of surface and adhesive. Interaction depends on dentin wettability, which can be enhanced either by increasing dentin surface energy or lowering the surface energy of adhesive. The objective was to examine the effect of dimethyl sulfoxide (DMSO) on demineralized dentin wettability and dentin organic matrix expansion. Acid-etched human dentin was used for sessile drop contact angle measurement to test surface wetting on 1-5% DMSO-treated demineralized dentin surface, and linear variable differential transformer (LVDT) to measure expansion/shrinkage of dentinal matrix. DMSO-water binary liquids were examined for surface tension changes through concentrations from 0 to 100% DMSO. Kruskal-Wallis and Mann-Whitney tests were used to test the differences in dentin wettability, expansion and shrinkage, and Spearman test to test the correlation between DMSO concentration and water surface tension. The level of significance was p<0.05. Pretreatment with 1-5% DMSO caused statistically significant concentration-dependent increase in wetting: the immediate contact angles decreased by 11.8% and 46.6% and 60s contact angles by 9.5% and 47.4% with 1% and 5% DMSO, respectively. DMSO-water mixtures concentration-dependently expanded demineralized dentin samples less than pure water, except with high (≥80%) DMSO concentrations which expanded demineralized dentin more than water. Drying times of LVDT samples increased significantly with the use of DMSO. Increased dentin wettability may explain the previously demonstrated increase in adhesive penetration with DMSO-treated dentin, and together with the expansion of collagen matrix after drying may also explain previously observed increase in dentin adhesive bonding. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The durability of phosphoric acid promoted bioglass-dentin interaction layer.

PubMed

Bakry, A S; Takahashi, H; Otsuki, M; Tagami, J

2013-04-01

Phosphoric acid-Bioglass 45S5 paste can create an interaction layer formed of calcium-phosphate crystals on the dentin surface. In this study, the efficiency of decreasing the dentin permeability exerted by the interaction layer formed between bioglass and dentin was compared to a resin-containing oxalate desensitizing agent (MS Coat One) and a resin-free oxalate desensitizing agent (Super Seal). Dentin permeability was measured before/after a brushing abrasion challenge, followed by examining the top and the fractured dentin surfaces with a field emission scanning electron microscope. Moreover, the chemical nature of the compounds formed on top of the dentin surface was examined using the field emission scanning electron microscope (FE-SEM) equipped with an energy-dispersive X-ray spectroscope (EDS), and the crystalline structures of the dentinal surfaces were examined by X-ray diffraction (XRD). The results showed that application of 45S5 bioglass paste to dentin was able to occlude patent dentinal tubule orifices with a layer of calcium-phosphate crystals, while the oxalate containing agents were able to form small crystals which were found in dentinal tubule orifices and scattered along the superficial parts of the dentinal tubule lumen. The brushing-abrasion challenge significantly increased the permeability of dentin treated by Super Seal and MS Coat One, while these challenges had no significant effect on the dentin permeability of specimens treated with 45S5 bioglass paste. The new technique provided better durability than two products available on the market. Moreover, our previous research showed the biocompatibility of using this technique on dental pulp cells, suggesting that this technique can aid in treating dentin hypersensitivity cases. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Extracellular ultrathin fibers sensitive to intracellular reactive oxygen species: Formation of intercellular membrane bridges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jung, Se-Hui; Park, Jin-Young; Joo, Jung-Hoon

2011-07-15

Membrane bridges are key cellular structures involved in intercellular communication; however, dynamics for their formation are not well understood. We demonstrated the formation and regulation of novel extracellular ultrathin fibers in NIH3T3 cells using confocal and atomic force microscopy. At adjacent regions of neighboring cells, phorbol 12-myristate 13-acetate (PMA) and glucose oxidase induced ultrathin fiber formation, which was prevented by Trolox, a reactive oxygen species (ROS) scavenger. The height of ROS-sensitive ultrathin fibers ranged from 2 to 4 nm. PMA-induced formation of ultrathin fibers was inhibited by cytochalasin D, but not by Taxol or colchicine, indicating that ultrathin fibers mainlymore » comprise microfilaments. PMA-induced ultrathin fibers underwent dynamic structural changes, resulting in formation of intercellular membrane bridges. Thus, these fibers are formed by a mechanism(s) involving ROS and involved in formation of intercellular membrane bridges. Furthermore, ultrastructural imaging of ultrathin fibers may contribute to understanding the diverse mechanisms of cell-to-cell communication and the intercellular transfer of biomolecules, including proteins and cell organelles.« less

Oral Pathology in Forensic Investigation.

PubMed

Shamim, Thorakkal

2018-01-01

Forensic odontology is the subdiscipline of dentistry which analyses dental evidence in the interest of justice. Oral pathology is the subdiscipline of dentistry that deals with the pathology affecting the oral and maxillofacial regions. This subdiscipline is utilized for identification through oral and maxillofacial pathologies with associated syndromes, enamel rod patterns, sex determination using exfoliative cytology, identification from occlusal morphology of teeth, and deoxyribonucleic acid profiling from teeth. This subdiscipline is also utilized for age estimation studies which include Gustafson's method, incremental lines of Retzius, perikymata, natal line formation in teeth, neonatal line, racemization of collagen in dentin, cemental incremental lines, thickness of the cementum, and translucency of dentin. Even though the expertise of an oral pathologist is not taken in forensic investigations, this paper aims to discuss the role of oral pathology in forensic investigation.

Oral Pathology in Forensic Investigation

PubMed Central

Shamim, Thorakkal

2018-01-01

Forensic odontology is the subdiscipline of dentistry which analyses dental evidence in the interest of justice. Oral pathology is the subdiscipline of dentistry that deals with the pathology affecting the oral and maxillofacial regions. This subdiscipline is utilized for identification through oral and maxillofacial pathologies with associated syndromes, enamel rod patterns, sex determination using exfoliative cytology, identification from occlusal morphology of teeth, and deoxyribonucleic acid profiling from teeth. This subdiscipline is also utilized for age estimation studies which include Gustafson's method, incremental lines of Retzius, perikymata, natal line formation in teeth, neonatal line, racemization of collagen in dentin, cemental incremental lines, thickness of the cementum, and translucency of dentin. Even though the expertise of an oral pathologist is not taken in forensic investigations, this paper aims to discuss the role of oral pathology in forensic investigation. PMID:29629322

Dentinal tubules occluded by bioactive glass-containing toothpaste exhibit high resistance toward acidic soft drink challenge.

PubMed

Bakri, M M; Hossain, M Z; Razak, F A; Saqina, Z H; Misroni, A A; Ab-Murat, N; Kitagawa, J; Saub, R B

2017-06-01

Dentine hypersensitivity is a common problem attributed by patent dentinal tubules. Ingredients incorporated in toothpastes aim to occlude patent dentinal tubules to minimize the dentine hypersensitivity. However, frequent consumption of acidic soft drinks may reverse the dentinal tubules' occlusion. In this in vitro study, the efficacy of dentinal tubules occluded by commercially available toothpastes to withstand different durations of an acidic soft drink challenge was investigated. One hundred and twenty dentine discs were divided into three groups. The discs from each group were brushed with toothpaste containing bioactive glass, arginine and control toothpaste. Each group was then divided into four subgroups and exposed to acidic soft drink over four different time durations. The scoring and the percentage of occluded dentinal tubules by Novamin-containing toothpaste was significantly better compared with arginine or the control toothpaste. Acidic soft drink challenge reduced the extent of dentinal tubules occlusion along with time. Dentinal tubules occluded by Novamin-containing toothpaste withstand the acidic challenge comparatively for a longer period. The findings demonstrated that occlusion of dentinal tubules is more efficient by the bioactive glass-containing toothpaste and thus may contribute to its better resistance to acidic soft drink challenge. © 2016 Australian Dental Association.

Dentin surface treatment using a non-thermal argon plasma brush for interfacial bonding improvement in composite restoration

PubMed Central

Ritts, Andy Charles; Li, Hao; Yu, Qingsong; Xu, Changqi; Yao, Xiaomei; Hong, Liang; Wang, Yong

2010-01-01

The objective of this study is to investigate the treatment effects of non-thermal atmospheric gas plasmas on dentin surfaces for composite restoration. Extracted unerupted human third molars were used by removing the crowns and etching the exposed dentin surfaces with 35% phosphoric acid gel. The dentin surfaces were treated by using a non-thermal atmospheric argon plasma brush for various durations. The molecular changes of the dentin surfaces were analyzed using FTIR/ATR and an increase in carbonyl groups on dentin surfaces was detected with plasma treated dentin. Adper Single Bond Plus adhesive and Filtek Z250 dental composite were applied as directed. To evaluate the dentin/composite interfacial bonding, the teeth thus prepared were sectioned into micro-bars as the specimens for tensile test. Student Newman Keuls tests showed that the bonding strength of the composite restoration to peripheral dentin was significantly increased (by 64%) after 30 s plasma treatment. However, the bonding strength to plasma treated inner dentin did not show any improvement. It was found that plasma treatment of peripheral dentin surface up to 100 s gave an increase in interfacial bonding strength, while a prolong plasma treatment of dentin surfaces, e.g., 5 min treatments, showed a decrease in interfacial bonding strength. PMID:20831586

Combining Bioactive Multifunctional Dental Composite with PAMAM for Root Dentin Remineralization

PubMed Central

Xiao, Shimeng; Liang, Kunneng; Weir, Michael D.; Cheng, Lei; Liu, Huaibing; Zhou, Xuedong; Ding, Yi; Xu, Hockin H. K.

2017-01-01

Objectives. The objectives of this study were to: (1) develop a bioactive multifunctional composite (BMC) via nanoparticles of amorphous calcium phosphate (NACP), 2-methacryloyloxyethyl phosphorylcholine (MPC), dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of silver (NAg); and (2) investigate the effects of combined BMC + poly (amido amine) (PAMAM) on remineralization of demineralized root dentin in a cyclic artificial saliva/lactic acid environment for the first time. Methods. Root dentin specimens were prepared and demineralized with 37% phosphoric acid for 15 s. Four groups were prepared: (1) root dentin control; (2) root dentin with BMC; (3) root dentin with PAMAM; (4) root dentin with BMC + PAMAM. Specimens were treated with a cyclic artificial saliva/lactic acid regimen for 21 days. Calcium (Ca) and phosphate (P) ion concentrations and acid neutralization were determined. The remineralized root dentin specimens were examined via hardness testing and scanning electron microscopy (SEM). Results. Mechanical properties of BMC were similar to commercial control composites (p = 0.913). BMC had excellent Ca and P ion release and acid-neutralization capability. BMC or PAMAM alone each achieved slight mineral regeneration in demineralized root dentin. The combined BMC + PAMAM induced the greatest root dentin remineralization, and increased the hardness of pre-demineralized root dentin to match that of healthy root dentin (p = 0.521). Significance. The excellent root dentin remineralization effects of BMC + PAMAM were demonstrated for the first time. BMC + PAMAM induced effective and complete root dentin remineralization in an acid challenge environment. The novel BMC + PAMAM method is promising for Class V and other restorations to remineralize and protect tooth structures. PMID:28772450

Combining Bioactive Multifunctional Dental Composite with PAMAM for Root Dentin Remineralization.

PubMed

Xiao, Shimeng; Liang, Kunneng; Weir, Michael D; Cheng, Lei; Liu, Huaibing; Zhou, Xuedong; Ding, Yi; Xu, Hockin H K

2017-01-22

Objectives . The objectives of this study were to: (1) develop a bioactive multifunctional composite (BMC) via nanoparticles of amorphous calcium phosphate (NACP), 2-methacryloyloxyethyl phosphorylcholine (MPC), dimethylaminohexadecyl methacrylate (DMAHDM) and nanoparticles of silver (NAg); and (2) investigate the effects of combined BMC + poly (amido amine) (PAMAM) on remineralization of demineralized root dentin in a cyclic artificial saliva/lactic acid environment for the first time. Methods . Root dentin specimens were prepared and demineralized with 37% phosphoric acid for 15 s. Four groups were prepared: (1) root dentin control; (2) root dentin with BMC; (3) root dentin with PAMAM; (4) root dentin with BMC + PAMAM. Specimens were treated with a cyclic artificial saliva/lactic acid regimen for 21 days. Calcium (Ca) and phosphate (P) ion concentrations and acid neutralization were determined. The remineralized root dentin specimens were examined via hardness testing and scanning electron microscopy (SEM). Results . Mechanical properties of BMC were similar to commercial control composites ( p = 0.913). BMC had excellent Ca and P ion release and acid-neutralization capability. BMC or PAMAM alone each achieved slight mineral regeneration in demineralized root dentin. The combined BMC + PAMAM induced the greatest root dentin remineralization, and increased the hardness of pre-demineralized root dentin to match that of healthy root dentin ( p = 0.521). Significance . The excellent root dentin remineralization effects of BMC + PAMAM were demonstrated for the first time. BMC + PAMAM induced effective and complete root dentin remineralization in an acid challenge environment. The novel BMC + PAMAM method is promising for Class V and other restorations to remineralize and protect tooth structures.

Effects of desensitizing toothpastes on the permeability of dentin after different brushing times: An in vitro study.

PubMed

Yang, Meng; Lin, Hong; Jiang, Ruodan; Zheng, Gang

2016-12-01

To investigate the effects of three commercially available desensitizing toothpastes on dentin permeability, and compare the efficacy of each product for reducing dentin permeability in the short term according to the frequency and duration of usage. 100 dentin discs with no caries were prepared from freshly extracted human third molar teeth. The dentin discs were brushed with three desensitizing toothpastes or with a non-desensitizing toothpaste and distilled water, which served as control. The 100 dentin slices were randomly divided into two groups (n= 50): one group underwent continuous brushing (brushed for 3 minutes continuously), and the other group underwent discontinuous brushing (brushed three times, each time for 1 minute). Then, the two groups were divided into five subgroups (n = 10) for the five brushing applications. Dentin permeability was measured with a hydraulic permeability system before and after brushing. All desensitizing toothpastes reduced dentin permeability significantly after treatment. Sensodyne Repair and Protect (calcium sodium phosphosilicate) and discontinuous brushing reduced dentin permeability significantly compared with continuous brushing. Dentin permeability values showed no significant difference between the three toothpastes after 3 minutes of continuous brushing. When comparing the three toothpastes under discontinuous brushing conditions after 3 minutes, Sensodyne Repair and Protect (calcium sodium phosphosilicate) reduced dentin permeability significantly. Sensodyne Repair and Protect (calcium sodium phosphosilicate) and discontinuous brushing reduced dentin permeability significantly compared with continuous brushing. Moreover, brushing with Sensodyne Repair and Protect (calcium sodium phosphosilicate) resulted in the lowest dentin permeability compared with those of the other two toothpastes. These results indicated that Sensodyne Repair and Protect may relieve dentin hypersensitivity.

Porous zirconia ceramic as an alternative to dentin for in vitro dentin barriers cytotoxicity test.

PubMed

Hu, Meng-Long; Lin, Hong; Jiang, Ruo-Dan; Dong, Li-Min; Huang, Lin; Zheng, Gang

2018-06-01

This study assessed the potential of porous zirconia ceramic as an alternative to dentin via an in vitro dentin barrier cytotoxicity test. The permeability of dentin and porous zirconia ceramic was measured using a hydraulic-conductance system, and their permeability was divided into two groups: high and low. Using an in vitro dentin barrier test, the cytotoxicity of dental materials by dentin and porous zirconia ceramic was compared within the same permeability group. The L-929 cell viability was assessed by MTT assay. The mean (SD) permeability of the high and low group for dentin was 0.334 (0.0873) and 0.147 (0.0377) μl min -1  cm -2  cm H 2 O -1 and for zirconia porous ceramic was 0.336 (0.0609) and 0.146 (0.0340) μl min -1  cm -2  cm H 2 O -1 . The cell viability of experimental groups which are the low permeability group was higher than that of the high permeability group for both dentin and porous zirconia ceramic as a barrier except for Maxcem Elite ™ by porous zirconia ceramic. There was no significant difference between dentin and porous zirconia ceramic in cell viability, within either the high or low permeability group for all materials. The SD for cell viability of the porous zirconia ceramic was less than that of the dentin, across all materials within each permeability group, except for Maxcem Elite ™ in the high permeability group. Porous zirconia ceramic, having similar permeability to dentin at the same thickness, can be used as an alternative to dentin for in vitro dentin barrier cytotoxicity tests. In vitro dentin barrier cytotoxicity tests when a standardized porous zirconia ceramic was used as a barrier could be useful for assessing the potential toxicity of new dental materials applied to dentin before applying in clinical and may resolve the issue of procuring human teeth when testing proceeds.

Entropy Drives the Formation of Salt Bridges in the Protein GB3.

PubMed

Zhang, Ning; Wang, Yefei; An, Liaoyuan; Song, Xiangfei; Huang, Qingshan; Liu, Zhijun; Yao, Lishan

2017-06-19

Salt bridges are very common in proteins. But what drives the formation of protein salt bridges is not clear. In this work, we determined the strength of four salt bridges in the protein GB3 by measuring the ΔpK a values of the basic residues that constitute the salt bridges with a highly accurate NMR titration method at different temperatures. The results show that the ΔpK a values increase with temperature, thus indicating that the salt bridges are stronger at higher temperatures. Fitting of ΔpK a values to the van't Hoff equation yields positive ΔH and ΔS values, thus indicating that entropy drives salt-bridge formation. Molecular dynamics simulations show that the protein and solvent make opposite contributions to ΔH and ΔS. Specifically, the enthalpic gain contributed from the protein is more than offset by the enthalpic loss contributed from the solvent, whereas the entropic gain originates from the desolvation effect. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dentinal permeation modeling

NASA Astrophysics Data System (ADS)

Trunina, Natalia; Derbov, Vladimir; Tuchin, Valery; Altshuler, Gregory

2008-06-01

Dentinal permeation is of interest in a wide context of tooth care and treatment, in particular, tooth color improvement using combination of chemical whitening agents and light activation. A simple model of dentinal permeation accounting for the morphology of human tooth dentine and including dentinal tubules, more dense and homogeneous peritubular dentine, and less dense and less homogeneous intertubular dentin is proposed. Calculation of permeability of dentine layer is carried out for H IIO and H IIO II versus the tubule diameter and tubule density taken from the microphotograph analysis. This opens the possibility to calculate the distribution of permeability over the tooth surface taking into account the variations of tubule diameter and density as well as those of the diffusion coefficients and layer thickness

Micro-shear bond strengths of adhesive resins to coronal dentin versus the floor of the pulp chamber.

PubMed

Toba, Shigemitsu; Veerapravati, Weeraporn; Shimada, Yasushi; Nikaido, Toru; Tagami, Junji

2003-09-01

To evaluate the micro-shear bond strengths to superficial coronal dentin and the floor of the pulp chamber using two dentin bonding systems and to compare the ultrastructure of the resin-dentin interface of the two regions. 30 non-carious molars were used to obtain 2 mm thick slabs of coronal dentin and dentin at the pulp chamber. The specimens in each region were divided into three sub-groups to be bonded as follows; Clearfil SE Bond was used according to the manufacturer's instructions, Single Bond was applied to either wet dentin (Blot dry Group) or air-dried dentin (Dry Group) after phosphoric acid etching. A resin composite cylinder 0.5 mm high and 0.75 mm in diameter formed using a vinyl tube was bonded to the dentin. Specimens were stored at 37 degrees C for 24 hours in water and then stressed in shear at a crosshead speed of 1 mm/minute. The data were analyzed with one-way ANOVA and Fisher's PLSD test at the 5% level of significance. In addition, the ultrastructure of cross-sectioned dentin surfaces, the conditioned dentin surface and the resin dentin interfaces were observed by SEM. The bond strengths of Clearfil SE Bond and the Single Bond Blot dry group were approximately 40 MPa in coronal dentin and 30 MPa in the dentin at the floor of the pulp chamber respectively. However, the bond strengths of Single Bond were significantly lower in the Dry condition (MPa) (P < 0.05). SEM observations revealed the thickness of the hybrid layer created by Clearfil SE Bond in coronal dentin and at the floor of the pulp chamber were less than 1.0 microm thick. For Single Bond, a 3-4 microm hybrid layer was created in coronal dentin, while a thinner hybrid layer was observed in the floor of the pulp chamber. Morphological and structural variations in dentin may have influenced the bond strengths of the bonding systems to the floor of the pulp chamber.

Wind-Driven Formation of Ice Bridges in Straits.

PubMed

Rallabandi, Bhargav; Zheng, Zhong; Winton, Michael; Stone, Howard A

2017-03-24

Ice bridges are static structures composed of tightly packed sea ice that can form during the course of its flow through a narrow strait. Despite their important role in local ecology and climate, the formation and breakup of ice bridges is not well understood and has proved difficult to predict. Using long-wave approximations and a continuum description of sea ice dynamics, we develop a one-dimensional theory for the wind-driven formation of ice bridges in narrow straits, which is verified against direct numerical simulations. We show that for a given wind stress and minimum and maximum channel widths, a steady-state ice bridge can only form beyond a critical value of the thickness and the compactness of the ice field. The theory also makes quantitative predictions for ice fluxes, which are particularly useful to estimate the ice export associated with the breakup of ice bridges. We note that similar ideas are applicable to dense granular flows in confined geometries.

Mechanical properties and molecular structure analysis of subsurface dentin after Er:YAG laser irradiation.

PubMed

He, Zhengdi; Chen, Lingling; Hu, Xuejuan; Shimada, Yasushi; Otsuki, Masayuki; Tagami, Junji; Ruan, Shuangchen

2017-10-01

The purpose of this study was to evaluate the chemical and mechanical modifications in subsurface dentin layer after Er: YAG (Erbium-Yttrium Aluminium Garnet) laser irradiation, as the guidance of new dental restorative materials specific for laser irradiated dentin. Dentin disks obtained from extracted human molars were prepared and exposed to a single pulse Er:YAG laser irradiation at 80mJ/pulse. After laser irradiation the mechanical and chemical characteristics of intertubular dentin in subsurface layer were studied using nanoindentation tester and micro-Raman spectromy (μ-RS). The dentin 5-50µm depth beneath the lased surface was determined as testing area. Two-way analysis of variance (ANOVA) were used to compare the mechanical values between lased and untreated subsurface dentin (P = 0.05). A laser affected subsurface dentin layer after Er:YAG laser treatment is present. The laser irradiation is considered to decrease the mechanical properties in the superficial subsurface layer (<15µm deep). There was no significant difference in nanohardness and Young's modulus between lased subsurface dentin and untreated dentin (p > 0.05) under the depth of 15µm. However, the dentin at 5µm and 10µm depth beneath the lased surface exhibited significantly lower (~ 47.8% and ~ 33.6% respectively) hardness (p < 0.05). Er:YAG laser irradiation affected both mineral and organic components in subsurface dentin layer, a higher degree of crystallinity and reduced organic compounds occurred in the lased subsurface dentin. Under the tested laser parameters, Er:YAG laser irradiation causes lower mechanical values and reduction of organic components in subsurface dentin, which has deleterious effects on resin adhesion to this area. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

The influence of the energy density and other clinical parameters on bond strength of Er:YAG-conditioned dentin compared to conventional dentin adhesion.

PubMed

Gisler, Gottfried; Gutknecht, Norbert

2014-01-01

The aim of this in vitro study was to optimise clinical parameters and the energy density of Er:YAG laser-conditioned dentin for class V fillings. Shear tests in three test series were conducted with 24 freshly extracted human third molars as samples for each series. For every sample, two orofacial and two approximal dentin surfaces were prepared. The study design included different laser energies, a thin vs a thick bond layer, the influence of adhesives as well as one-time- vs two-time treatment. The best results with Er:YAG-conditioned dentin were obtained with fluences just above the ablation threshold (5.3 J/cm(2)) in combination with a self-etch adhesive, a thin bond layer and when bond and composite were two-time cured. Dentin conditioned this way reached an averaged bond strength of 23.32 MPa (SD 5.3) and 24.37 MPa (SD 6.06) for two independent test surfaces while showing no statistical significance to conventional dentin adhesion and two-time treatment with averaged bond strength of 24.93 MPa (SD 11.51). Significant reduction of bond strength with Er:YAG-conditioned dentin was obtained when using either a thick bond layer, twice the laser energy (fluence 10.6 J/cm(2)) or with no dentin adhesive. The discussion showed clearly that in altered (sclerotic) dentin, e.g. for class V fillings of elderly patients, bond strengths in conventional dentin adhesion are constantly reduced due to the change of the responsibles, bond giving dentin structures, whereas for Er:YAG-conditioned dentin, the only way to get an optimal microretentive bond pattern is a laser fluence just above the ablation threshold of sclerotic dentin.

The effect of Er:YAG laser irradiation on the bond stability of self-etch adhesives at different dentin depths.

PubMed

Karadas, Muhammet; Çağlar, İpek

2017-07-01

The aim of this study was to evaluate the effect of Er:YAG laser irradiation on the micro-shear bond strength of self-etch adhesives to the superficial dentin and the deep dentin before and after thermocycling. Superficial dentin and deep dentin surfaces were prepared by flattening of the occlusal surfaces of extracted human third molars. The deep or superficial dentin specimens were randomized into three groups according to the following surface treatments: group I (control group), group II (Er:YAG laser; 1.2 W), and group III (Er:YAG laser; 0.5 W). Clearfil SE Bond or Clearfil S 3 Bond was applied to each group's dentin surfaces. After construction of the composite blocks on the dentin surface, the micro-shear bond testing of each adhesive was performed at 24 h or after 15,000 thermal cycles. The data were analyzed using a univariate analysis of variance and Tukey's test (p < 0.05). Laser irradiation in superficial dentin did not significantly affect bond strength after thermocycling (p > 0.05). However, deep-dentin specimens irradiated with laser showed significantly higher bond strengths than did control specimens after thermocycling (p < 0.05). Thermocycling led to significant deterioration in the bond strengths of all deep-dentin groups. The stable bond strength after thermocycling was measured for all of the superficial-dentin groups. No significant difference was found between the 0.5 and 1.2 W output power settings. In conclusion, the effect of laser irradiation on the bond strength of self-etch adhesives may be altered by the dentin depth. Regardless of the applied surface treatment, deep dentin showed significant bond degradation.

Morphology and chemical composition of dentin in permanent first molars with the diagnose MIH.

PubMed

Heijs, Suzanne C B; Dietz, Wolfram; Norén, Jörgen G; Blanksma, Nynke G; Jälevik, Birgitta

2007-01-01

The purpose of this investigation was to study the morphology and distribution of some inorganic elements in dentin in first permanent molars from children with Molar-Incisor Hypomineralization (MIH). Sixty four tooth sections from thirty two children were examined in polarized light. Fifteen representative sections were selected for SEM/XRMA analysis; 5 were used for SEM analysis and 10 for XRMA analysis. No morphological changes in the dentin were revealed in polarized light microscopy (PLM). However, in all but two sections interglobular dentin was found. The SEM analyzes confirmed the findings of the PLM with no structural changes to be found in the dentin. The XRMA results showed a difference in the concentration of elements between dentin below normal and dentin below carious or hypomineralized enamel. Elements related to organic matter appeared with higher values in dentin below hypomineralized and carious enamel. The morphological and chemical findings in dentin below hypomineralized enamel imply that the odontoblasts are not affected in cases of MIH, but may be affected by hypocalcemia, reflected by the presence of interglobular dentin.

Evaluation Of The Shear Bond Strength Between Dentin And Dental Luting Cement Following Dentin Surface Treatment By 980 Nm Diode Laser And Desensitizing Agent

NASA Astrophysics Data System (ADS)

Ibrahim, T.; Gheith, M.

2011-09-01

Dentin hypersensitivity is described clinically as an exaggerated response to non-noxious sensory stimuli. Current treatment is concentrating on two approaches; to occlude the dentinal tubules or to block neural transmission. This is achieved through using dentin desensitizers and low power lasers. Forty eight freshly extracted human molar teeth were used in this study and divided equally into three groups. Group 1) control group, group 2) laser treated dentin surface group, and group 3) desensitizing agent dentin surface group. Scanning electron microscopic analysis of laser treated group showed melted globules, no carbonization, recrystalization and crystal growth of the apatite in some areas. In diode laser dentin surface treated group showed the highest shear bond strength mean value.

Effect and Stability of Poly(Amido Amine)-Induced Biomineralization on Dentinal Tubule Occlusion

PubMed Central

Gao, Yuan; Liang, Kunneng; Li, Jianshu; Yuan, He; Liu, Hongling; Duan, Xiaolei; Li, Jiyao

2017-01-01

In recent years, scientists have developed various biomaterials to remineralize human teeth to treat dentine hypersensitivity. Poly(amido amine) (PAMAM) dendrimers have become a research focus in this field. It has been demonstrated that PAMAM is able to create precipitates both on the surface of and within the dentinal tubules, however, there is little information about its effect on reducing dentine permeability in vitro. This study aimed to evaluate the in vitro effectiveness and stability of the fourth generation amine-terminated PAMAM on dentinal tubule occlusion, especially on dentine permeability. Sodium fluoride (NaF), which has been widely used as a desensitizing agent, is regarded as positive control. Demineralized sensitive dentine samples were coated with PAMAM or sodium fluoride solutions and soaked in artificial saliva (AS) at 37 °C for different periods. Four weeks later, samples in each group were then equally split into two subgroups for testing using a brushing challenge and an acid challenge. Dentine permeability of each specimen was measured before and after each challenge using a fluid filtration system. Dentine morphology and surface deposits were characterized by scanning electron microscope (SEM) and analyzed with Image-Pro Plus software. Data were evaluated through multifactorial ANOVA with repeated measures and pair-wise comparisons at a level of 5%. The results showed that PAMAM and NaF significantly reduced dentine permeability to 25.1% and 20.7%. Both of them created precipitates on dentine surfaces after AS immersion for 28 days. PAMAM-induced biomineralization not only on dentine surfaces, but also deeper in dentinal tubules, significantly reduced dentine permeability. Moreover, PAMAM-induced biomineralization elicited excellent stable occlusion effects after acid challenge. In conclusion, PAMAM demonstrated a strong ability to resist acid and showed great potential to be used in the treatment of dentine hypersensitivity in future. PMID:28772744

Dental wear, wear rate, and dental disease in the African apes.

PubMed

Elgart, Alison A

2010-06-01

The African apes possess thinner enamel than do other hominoids, and a certain amount of dentin exposure may be advantageous in the processing of tough diets eaten by Gorilla. Dental wear (attrition plus abrasion) that erodes the enamel exposes the underlying dentin and creates additional cutting edges at the dentin-enamel junction. Hypothetically, efficiency of food processing increases with junction formation until an optimal amount is reached, but excessive wear hinders efficient food processing and may lead to sickness, reduced fecundity, and death. Occlusal surfaces of molars and incisors in three populations each of Gorilla and Pan were videotaped and digitized. The quantity of incisal and molar occlusal dental wear and the lengths of dentin-enamel junctions were measured in 220 adult and 31 juvenile gorilla and chimpanzee skulls. Rates of dental wear were calculated in juveniles by scoring the degree of wear between adjacent molars M1 and M2. Differences were compared by principal (major) axis analysis. ANOVAs compared means of wear amounts. Pearson correlation coefficients were calculated to compare the relationship between molar wear and incidence of dental disease. Results indicate that quantities of wear are significantly greater in permanent incisors and molars and juvenile molars of gorillas compared to chimpanzees. The lengths of dentin-enamel junctions were predominantly suboptimal. Western lowland gorillas have the highest quantities of wear and the most molars with suboptimal wear. The highest rates of wear are seen in Pan paniscus and Pan t. troglodytes, and the lowest rates are found in P.t. schweinfurthii and G. g. graueri. Among gorillas, G. b. beringei have the highest rates but low amounts of wear. Coefficients between wear and dental disease were low, but significant when all teeth were combined. Gorilla teeth are durable, and wear does not lead to mechanical senescence in this sample.

Effect of quaternary ammonium and silver nanoparticle-containing adhesives on dentin bond strength and dental plaque microcosm biofilms

PubMed Central

Zhang, Ke; Melo, Mary Anne S.; Cheng, Lei; Weir, Michael D.; Bai, Yuxing; Xu, Hockin H. K.

2012-01-01

Objectives Antibacterial bonding agents are promising to hinder the residual and invading bacteria at the tooth-restoration interfaces. The objectives of this study were to develop an antibacterial bonding agent by incorporation of quaternary ammonium dimethacrylate (QADM) and nanoparticles of silver (NAg), and to investigate the effect of QADM-NAg adhesive and primer on dentin bond strength and plaque microcosm biofilm response for the first time. Methods Scotchbond Multi-Purpose adhesive and primer were used as control. Experimental adhesive and primer were made by adding QADM and NAg into control adhesive and primer. Human dentin shear bond strengths were measured (n = 10). A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate biofilm metabolic activity, colony-forming unit (CFU) counts, lactic acid production, and live/dead staining assay (n = 6). Results Adding QADM and NAg into adhesive and primer did not compromise the dentin shear bond strength which ranged from 30 to 35 MPa (p > 0.1). Scanning electron microscopy (SEM) examinations revealed numerous resin tags, which were similar for the control and the QADM and NAg groups. Adding QADM or NAg markedly reduced the biofilm viability, compared to adhesive control. QADM and NAg together in the adhesive had a much stronger antibacterial effect than using each agent alone (p < 0.05). Adding QADM and NAg in both adhesive and primer had the strongest antibacterial activity, reducing metabolic activity, CFU, and lactic acid by an order of magnitude, compared to control. Significance Without compromising dentin bond strength and resin tag formation, the QADM and NAg containing adhesive and primer achieved strong antibacterial effects against microcosm biofilms for the first time. QADM-NAg adhesive and primer are promising to combat residual bacteria in tooth cavity and invading bacteria at the margins, thereby to inhibit secondary caries. QADM and NAg incorporation may have a wide applicability to other dental bonding systems. PMID:22592165

Interaction between Octenidine-based Solution and Sodium Hypochlorite: A Mass Spectroscopy, Proton Nuclear Magnetic Resonance, and Scanning Electron Microscopy-based Observational Study.

PubMed

Thaha, Khaleel Ahamed; Varma, R Luxmi; Nair, Mali G; Sam Joseph, V G; Krishnan, Unni

2017-01-01

Octenisept (OCT; Schülke & Mayr, Nordersdedt, Germany), an antimicrobial, antibiofilm agent and a promising root canal irrigant, can be potentially combined with sodium hypochlorite (NaOCl) during endodontic treatment. The aim of this study was first to identify the precipitate formed on the interaction between OCT and NaOCl and secondly to compare its effect on dentinal tubules with that of precipitate formed on combining chlorhexidine (CHX) and NaOCl. This observational study was conducted in 3 stages. Initially, the color changes and precipitate formation were assessed when the test solution 0.1% OCT and 5.2% NaOCl were mixed. Color changes were compared with those observed when 2% CHX was mixed with 5.2% NaOCl. The residue obtained on combining OCT and NaOCl was subjected to proton nuclear magnetic resonance ( 1 H NMR) and mass spectrometric (MS) analysis. In the final stage, dentinal surfaces irrigated alternatively with OCT and NaOCl were compared using scanning electron microscopy (SEM) with the dentinal surface irrigated with CHX and NaOCl. The OCT-NaOCl mixture changed in color from initial milky white to transparent over time, whereas the CHX-NaOCl mixture showed an immediate peach-brown discoloration. 1 H NMR and MS analysis established that the whitish precipitate obtained on combining OCT and NaOCl solutions correlated with the structure of phenoxyethanol (PE). SEM revealed dense precipitate occluding the dentinal tubules with the CHX and NaOCl group, whereas the precipitate was sparse and partially occluded in the OCT and NaOCl group. The whitish precipitate formed with the OCT-NaOCl mixture was identified as PE, a compound already present in OCT, and it partly occluded the dentinal tubules. Copyright © 2016 American Association of Endodontists. All rights reserved.

Effect of quaternary ammonium and silver nanoparticle-containing adhesives on dentin bond strength and dental plaque microcosm biofilms.

PubMed

Zhang, Ke; Melo, Mary Anne S; Cheng, Lei; Weir, Michael D; Bai, Yuxing; Xu, Hockin H K

2012-08-01

Antibacterial bonding agents are promising to hinder the residual and invading bacteria at the tooth-restoration interfaces. The objectives of this study were to develop an antibacterial bonding agent by incorporation of quaternary ammonium dimethacrylate (QADM) and nanoparticles of silver (NAg), and to investigate the effect of QADM-NAg adhesive and primer on dentin bond strength and plaque microcosm biofilm response for the first time. Scotchbond Multi-Purpose adhesive and primer were used as control. Experimental adhesive and primer were made by adding QADM and NAg into control adhesive and primer. Human dentin shear bond strengths were measured (n = 10). A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate biofilm metabolic activity, colony-forming unit (CFU) counts, lactic acid production, and live/dead staining assay (n = 6). Adding QADM and NAg into adhesive and primer did not compromise the dentin shear bond strength which ranged from 30 to 35MPa (p>0.1). Scanning electron microscopy (SEM) examinations revealed numerous resin tags, which were similar for the control and the QADM and NAg groups. Adding QADM or NAg markedly reduced the biofilm viability, compared to adhesive control. QADM and NAg together in the adhesive had a much stronger antibacterial effect than using each agent alone (p<0.05). Adding QADM and NAg in both adhesive and primer had the strongest antibacterial activity, reducing metabolic activity, CFU, and lactic acid by an order of magnitude, compared to control. Without compromising dentin bond strength and resin tag formation, the QADM and NAg containing adhesive and primer achieved strong antibacterial effects against microcosm biofilms for the first time. QADM-NAg adhesive and primer are promising to combat residual bacteria in tooth cavity and invading bacteria at the margins, thereby to inhibit secondary caries. QADM and NAg incorporation may have a wide applicability to other dental bonding systems. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Effect of Biomineralization Ability on Push-out Strength of Proroot Mineral Trioxide Aggregate, Mineral Trioxide Aggregate Branco, and Calcium Phosphate Cement on Dentin: An In vitro Evaluation.

PubMed

Revankar, Vanita D; Prathap, M S; Shetty, K Harish Kumar; Shahul, Azmin; Sahana, K

2017-11-01

Biomineralization is a process which leads to the formation of an interfacial layer with tag-like structures at the cement-dentin interface. It is due to interaction of mineral trioxide aggregate (MTA) and Portland cement with dentin in phosphate-buffered solution (PBS). This study is aimed to evaluate the effect of influence of biomineralization process on push-out bond strength of ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK, USA), MTA Branco (Angelus Soluc¸o˜es Odontolo´gicas, Londrina, PR, Brazil) and calcium phosphate cement (BioGraft CPC). The aim of this study was to evaluate the effect of biomineralization process on the push-out strength of ProRoot MTA, MTA Branco, and CPC after mixing with 0.2% chlorhexidine gluconate solution (0.2% CHX) and 2% lidocaine solution (2% LA) on the bond strength of MTA-dentin. Dentin discs with uniform cavities were restored with ProRoot MTA, MTA Branco, and calcium phosphate cement after mixing with 0.2% CHX solution and 2% lidocaine solution. The samples were uniformly distributed into two groups. Experimental group being immersed in PBS solution and control group being immersed in saline for 2 months. Instron testing machine (Model 4444; Instron Corp., Canton, MA, USA) was used to determine the bond strength. A two-way analysis of variance and post hoc analysis by Bonferroni test. All samples immersed in experimental group displayed a significantly greater resistance to displacement than that observed for the samples in control group ( P < 0.05). MTAs displayed a significantly greater resistance to displacement than calcium phosphate cements. The main conclusion of this study was that the push-out bond strength of the cements, mainly the MTA groups, was positively influenced by the biomineralization process.

Experimental resin cements containing bioactive fillers reduce matrix metalloproteinase-mediated dentin collagen degradation.

PubMed

Osorio, Raquel; Yamauti, Monica; Sauro, Salvatore; Watson, Thimoty F; Toledano, Manuel

2012-09-01

Collagen dentin matrix may represent a suitable scaffold to be remineralized in the presence of bioactive materials. The purpose of this study was to determine if experimental resin cements containing bioactive fillers may modulate matrix metalloproteinase-mediated collagen degradation of etched dentin. Human dentin beams demineralized using 10% phosphoric acid or 0.5 mol/L EDTA were infiltrated with the following experimental resins: (1) unfilled resin, (2) resin with Bioglass 45S5 particles (Sylc; OSspray Ltd, London, UK), and (3) resin with β-tricalcium phosphate-modified calcium silicate cement (HCAT-β) particles. The filler/resin ratio was 40/60 wt%. The specimens were stored in artificial saliva, and the determination of C-terminal telopeptide (ICTP) was performed by radioimmunoassay after 24 hours, 1 week, and 4 weeks. Scanning electron microscopic analysis of dentin surfaces after 4 weeks of storage was also executed. Collagen degradation was prominent both in phosphoric acid and EDTA-treated dentin. Resin infiltration strongly reduced the MMP activity in demineralized dentin. Resin-containing Bioglass 45S5 particles exerted higher and more stable protection of collagen at all tested dentin states and time points. HCAT-β induced collagen protection from MMPs only in EDTA-treated specimens. Dentin remineralization was achieved when dentin was infiltrated with the resin cements containing bioactive fillers. MMP degradation of dentin collagen is strongly reduced in resin-infiltrated dentin. The inclusion of Bioglass 45S5 particles exerted an additional protection of collagen during dentin remineralization. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Dentin remineralization in acid challenge environment via PAMAM and calcium phosphate composite.

PubMed

Liang, Kunneng; Weir, Michael D; Xie, Xianju; Wang, Lin; Reynolds, Mark A; Li, Jiyao; Xu, Hockin H K

2016-11-01

The objective of this study was to investigate the effects of poly (amido amine) (PAMAM), composite with nanoparticles of amorphous calcium phosphate (NACP), and the combined PAMAM+NACP nanocomposite treatment, on remineralization of demineralized dentin in a cyclic artificial saliva/lactic acid environment for the first time. Dentin specimens were prepared and demineralized with 37% phosphoric acid for 15s. Four groups were prepared: (1) dentin control, (2) dentin coated with PAMAM, (3) dentin with NACP composite, (4) dentin with PAMAM+NACP. Specimens were treated with a cyclic artificial saliva/lactic acid regimen for 21days. Acid neutralization and calcium (Ca) and phosphate (P) ion concentrations were measured. The remineralized dentin specimens were examined by scanning electron microscopy (SEM) and hardness testing. NACP nanocomposite had mechanical properties similar to commercial control composites (p>0.1). NACP composite had acid-neutralization and Ca and P ion release capability. PAMAM or NACP composite each alone achieved remineralization and increased the hardness of demineralized dentin (p<0.05). PAMAM+NACP nanocomposite achieved the greatest mineral regeneration in demineralized dentin and the greatest hardness increase in demineralized dentin, which approached the hardness of healthy dentin (p>0.1). The superior remineralization efficacy of PAMAM+NACP was demonstrated for the first time. PAMAM+NACP induced remineralization in demineralized dentin in an acid challenge environment, when conventional remineralization methods such as PAMAM did not work well. The novel PAMAM+NACP composite approach is promising for a wide range of dental applications to inhibit caries and protect tooth structures. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Tannic acid for smear layer removal: pilot study with scanning electron microscope.

PubMed

Bitter, N C

1989-04-01

The effects of a 25% tannic acid solution applied to the surface of prepared dentin was compared with untreated prepared dentin surfaces. The following results were demonstrated by electron microscope observation: (1) cavity preparations created an amorphous dentinal smear layer, (2) placement of a 25% tannic acid solution for 15 seconds removed the smear layer, (3) the contents of the dentinal tubules were not removed and no enlargement of dentinal tubules was found, and (3) a clean dentinal surface was observed.

The effect of 25% tannic acid on prepared dentin: a scanning electron microscope-methylene blue dye study.

PubMed

Bitter, N C

1990-07-01

The effect on the permeability of prepared dentin treated with 25% tannic acid and 6% citric acid was compared with the untreated dentinal surface. Methylene blue was applied to the dentin surface after treatment to evaluate penetration into dentinal tubules. The tannic acid solution reduced or prevented dye penetration of the dentinal tubules. Citric acid treatment permitted severe penetration. The 25% tannic acid solution removed the smear layer while inhibiting penetration of the dye.

Presence of matrix vesicles in the body of odontoblasts and in the inner third of dentinal tissue: a scanning electron microscopic study.

PubMed

Garcés-Ortíz, Maricela; Ledesma-Montes, Constantino; Reyes-Gasga, José

2013-05-01

The aim of this report is to present the results of a scanning electron microscopic study on the presence of matrix vesicles (MVs) found in human dentine. Dentin tissue from 20 human bicuspids was analyzed by means of scanning electron microscopy. MVs were found as outgrowths of the cellular membrane of the odontoblastic body, the more proximal portion of the odontoblastic process before entering the dentinal tubule and in the odontoblastic process within the inner third of the dentin. Size of MVs varied depending on location. In the inner third of dentin, they were seen in diverse positions; as membranal outgrowths, deriving from the odontoblastic process, lying free in the intratubular space and attached to the dentinal wall. Sometimes, they were seen organized forming groups of different sizes and shapes or as multivesicular chains running from the surface of the odontoblastic process to the tubular wall. MVs were present in places never considered: 1) the body of odontoblasts; 2) the most proximal part of the odontoblastic processes before entering the circumpulpal dentine and also: 3) in the inner third of dentinal tissue. According to our results, MVs not only participate during mantle dentin mineralization during early dentinogenesis, they also contribute during the mineralization process of the inner dentin.

The effect of MTA application on the affected dentine remineralization after partial caries excavation (in vivo)

NASA Astrophysics Data System (ADS)

Pratiwi, A. R.; Meidyawati, R.; Djauharie, N.

2017-08-01

On deep carious lesions, only thin dentine remains, causing a high risk of pulp exposure during the removal of all infected dentine. A minimally invasive technique is required, such as a partial caries excavation method in the infected dentine tissue and the use of bioactive material that can promote (Mineral Trioxide Aggregate) MTA remineralization. To compare the remineralization of deep carious lesion-affected dentine with the removal of some and all the infected dentine after the application of MTA. Subjects were divided into two groups: group I had only some parts of the infected dentine removed before MTA application, while group II had all the infected dentine removed before MTA application. Each group was measured on the pixel grey value before the treatment and again four weeks after the MTA application, and then the results were compared. Furthermore, the enhancement of both groups’ grey values were compared. Remineralization occurred in both groups after the MTA application. There was no significant difference in the remineralization level of the affected dentine in both groups I and II four weeks after the MTA application. Remineralization occurred in the affected dentine in both groups, either by removing only some parts or all the infected dentine in the deep carious lesion.

Treatment of collagenase-induced osteoarthritis with a viral vector encoding TSG-6 results in ectopic bone formation.

PubMed

Broeren, Mathijs G A; Di Ceglie, Irene; Bennink, Miranda B; van Lent, Peter L E M; van den Berg, Wim B; Koenders, Marije I; Blaney Davidson, Esmeralda N; van der Kraan, Peter M; van de Loo, Fons A J

2018-01-01

Tumor necrosis factor-inducible gene 6 (TSG-6) has anti-inflammatory and chondroprotective effects in mouse models of inflammatory arthritis. Because cartilage damage and inflammation are also observed in osteoarthritis (OA), we determined the effect of viral overexpression of TSG-6 in experimental osteoarthritis. Bone marrow-derived cells were differentiated to multinucleated osteoclasts in the presence of recombinant TSG-6 or after transduction with a lentiviral TSG-6 expression vector. Multi-nucleated osteoclasts were analyzed after tartrate resistant acid phosphatase staining and resorption activity was determined on dentin slices. Collagenase-induced osteoarthritis (CIOA) was induced in C57BL/6 mice after intra-articular injection of an adenoviral TSG-6 or control luciferase expression vector. Inflammation-related protease activity was measured using bioluminescent Prosense probes. After a second adenovirus injection, cartilage damage was assessed in histological sections stained with Safranin-O. Ectopic bone formation was scored in X-ray images of the affected knees. TSG-6 did not inhibit the formation of multi-nucleated osteoclasts, but caused a significant reduction in the resorption activity on dentin slices. Adenoviral TSG-6 gene therapy in CIOA could not reduce the cartilage damage compared to the luciferase control virus and no significant difference in inflammation-related protease activity was noted between the TSG-6 and control treated group. Instead, X-ray analysis and histological analysis revealed the presence of ectopic bone formation in the TSG-6 treated group. Gene therapy based on the expression of TSG-6 could not provide cartilage protection in experimental osteoarthritis, but instead resulted in increased ectopic bone formation.

The effect of dentin on the pulp tissue dissolution capacity of sodium hypochlorite and calcium hydroxide.

PubMed

Slutzky-Goldberg, Iris; Hanut, Aiham; Matalon, Shlomo; Baev, Valery; Slutzky, Hagay

2013-08-01

Sodium hypochlorite (NaOCl) and calcium hydroxide (Ca[OH]2) have tissue dissolution capacity. The aim of this study was to evaluate the potential effect of dentin on their tissue dissolution capacity in a novel dentin model. Dentin models were prepared from 25 freshly extracted human molar teeth; the crowns were separated from the roots, and a rectangular inner shape was prepared. Pulp tissue samples adjusted to similar weights of 6.5 ± 0.2 mg were randomly divided into 6 groups: NaOCl groups in test tubes or dentin models for 1 hour, Ca(OH)2 groups in test tubes or dentin models for 1 week, and control groups saline in test tubes or dentin models for 1 week. The final weights after the experimental period were checked and compared with the initial weights. The differences were statistically analyzed. The tissue dissolution capacity of Ca(OH)2 was affected by the presence of dentin. Similarly, NaOCl lost its effect on the pulp tissue after incubation in dentin. Comparison between all test groups showed highly significant differences (P < .001). Dentin has a detrimental effect on the ability of NaOCl and Ca(OH)2 to dissolve pulp tissue. The dentin model appears to be an efficient tool for the study of interactions between local endodontic medicaments, dentin, and pulp tissue. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Dentin hypersensitivity treatment by CO2 laser: the influence of the density of dentin tubules and laser-beam incidence

NASA Astrophysics Data System (ADS)

Colojoara, Carmen; Gabay, Shimon; van der Meulen, Freerk W.; van Gemert, Martin J. C.; Miron, Mariana I.; Mavrantoni, Androniki

1997-12-01

Dentin hypersensitivity is considered to be a consequence of the presence of open dentin tubules on the exposed dentin surface. Various methods and materials used in the treatment of this disease are directed to achieve a tubule's occlusion. The purpose of this study was to evaluate under scanning electron microscopy and clinical method the sealing effects of CO2 laser on dentin tubules of human teeth without any damages of the surrounding tissues. Samples of freshly extracted noncarious 3rd molars were used. The teeth were randomly divided in to two groups A and B. The samples of group A were exposed to laser beam in cervical area, directed parallel to their dentin tubules. The teeth of group B were sectioned through a hypothetical carious lesion and lased perpendicularly or obliquely of the dentin tubules. The CO2 laser, at 10.6 micrometers wavelength, was operated only in pulse mode and provided 6.25 - 350 mJ in a burst of 25 pulses each of 250 microsecond(s) time duration with a 2 ms time interval between successive pulses (repetition rate up to 500 mH). Melting of dentin surface and partial closure of exposed dentin tubules were found for all specimens at 6.25 to 31.25 mJ energy. Our results indicated that using CO2 laser in a parallel orientation of laser beam with dentin tubules, the dentin sensitivity can be reduced without any damages of pulp vitality.

Angiogenic mechanisms of human dental pulp and their relationship with substance P expression in response to occlusal trauma.

PubMed

Caviedes-Bucheli, J; Gomez-Sosa, J F; Azuero-Holguin, M M; Ormeño-Gomez, M; Pinto-Pascual, V; Munoz, H R

2017-04-01

Angiogenesis is the formation of new blood vessels based on a pre-existing vasculature. It comprises two processes, sprouting of endothelial cells and the division of vessels due to abnormal growth of the microvasculature. It has been demonstrated that substance P (SP) can induce angiogenesis either by modulating endothelial cell growth (direct mechanism) or by attracting cells with angiogenic potential to the injury site (indirect mechanism). Therefore, the purpose of this article is to review the angiogenic mechanisms that regulate mineralized tissue formation in human dental pulp tissue and their relationship with SP expression as a defence response to stimuli such as the masticatory function and occlusal trauma. Articles included in this review were searched in PubMed, Scopus and ISI Web of Science databases, combining the following keywords: human dentine pulp, angiogenesis, angiogenic growth factors, neuropeptides, substance P, neurogenic inflammation, dentine matrix, dentinogenesis, occlusal trauma and dental occlusion. It is concluded that human dental pulp tissue responds to occlusal trauma and masticatory function with a neurogenic inflammatory phenomenon in which SP plays an important role in the direct and indirect mechanisms of angiogenesis by the action evoked via NK1 receptors at different cells, such as fibroblasts, endothelial and inflammatory cells, leading to new blood vessel formation which are needed to stimulate mineralized tissue formation as a defence mechanism. © 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Water permeability, hybrid layer long-term integrity and reaction mechanism of a two-step adhesive system.

PubMed

Grégoire, Geneviève; Dabsie, Firas; Delannée, Mathieu; Akon, Bernadette; Sharrock, Patrick

2010-07-01

Our aim was to investigate the reaction mechanism of formation of the hybrid layer by a HEMA-containing self-etch adhesive and to study fluid filtration, contact angle and interfacial ultrastructure by SEM following a 1 year ageing period. Acidic behaviour and chemical interactions between Silorane System Adhesive and dentine were studied by potentiometric titrations, atomic absorption spectroscopy and infrared spectroscopy. The hydrophilicity of the adhesive was evaluated using the sessile drop method and dentine permeability by hydraulic conductance. The morphological study of the dentine/adhesive system interface was conducted using SEM. The Silorane System Adhesive behaved as a multi-acid with several different pK(a) values. When the adhesive was in contact with dentine, the acid was progressively consumed and calcium ions were released. The acrylate substituted phosphonate bound strongly to apatite crystals. The polyacrylic acid copolymer reacted with calcium ions and formed an interpenetrating polymer network (IPN). Water contact angle measurements showed rapid spreading on primer (angles reached 15 degrees at 30s) and larger contact angles when the Silorane bonding layer was added (from over 60 degrees to 44 degrees ). A thick, homogeneous hybrid layer was observed both initially and after 1 year of ageing, with a corresponding hydraulic conductance of -48.50% initially and -52.07% at 12 months. The Silorane System Adhesive is capable of both dissolving calcium ions and binding to apatite surfaces. The results showed the hydrophilicity of the adhesive, which formed an IPN-like hybrid layer that conserved adequate impermeability over a 1-year period. Copyright 2010 Elsevier Ltd. All rights reserved.

Insulin-like growth factor 1 can promote the osteogenic differentiation and osteogenesis of stem cells from apical papilla.

PubMed

Wang, Sainan; Mu, Jinquan; Fan, Zhipeng; Yu, Yan; Yan, Ming; Lei, Gang; Tang, Chunbo; Wang, Zilu; Zheng, Yangyu; Yu, Jinhua; Zhang, Guangdong

2012-05-01

Insulin-like growth factor 1 (IGF-1) plays an important role in the regulation of tooth root development, and stem cells from apical papilla (SCAPs) are responsible for the formation of root pulp and dentin. To date, it remains unclear whether IGF-1 can regulate the function of SCAPs. In this study, SCAPs were isolated and purified from human immature root apex, and stimulated by 100 ng/mL exogenous IGF-1. The effects of IGF-1 on the proliferation and differentiation of SCAPs were subsequently investigated. IGF-1 treated SCAPs presented the morphological and ultrastructural changes. Cell proliferation, alkaline phosphatase (ALP) activity and mineralization capacity of SCAPs were increased by IGF-1. Western blot and quantitative RT-PCR analyses further demonstrated that the expression of osteogenic-related proteins and genes (e.g., alkaline phosphatase, runt-related transcription factor 2, osterix, and osteocalcin) was significantly up-regulated in IGF-1 treated SCAPs, whereas the expression of odontoblast-specific markers (e.g., dentin sialoprotein and dentin sialophosphoprotein) was down-regulated by IGF-1. In vivo results revealed that IGF-1 treated SCAPs mostly gave birth to bone-like tissues while untreated SCAPs mainly generated dentin-pulp complex-like structures after transplantation. The present study revealed that IGF-1 can promote the osteogenic differentiation and osteogenesis capacity of SCAPs, but weaken their odontogenic differentiation and dentinogenesis capability, indicating that IGF-1 treated SCAPs can be used as a potential candidate for bone tissue engineering. Copyright © 2011 Elsevier B.V. All rights reserved.

Laboratory testing of precast paving notch system.

DOT National Transportation Integrated Search

2008-02-01

Bridge approach pavement settlement and the resulting formation of bumps at the end : of bridges is a recurring problem on a number of Iowa bridges. One of the contributing : factors in this settlement is failure of the bridge paving notch. A p...

Prostate Cancer Progression and Serum SIBLING (Small Integrin Binding N-Linked Glycoprotein)Levels

DTIC Science & Technology

2007-10-01

termed SIBLINGs (for small integrin binding ligand N-linked glycoproteins) whose members include bone sialoprotein (BSP), osteopontin (OPN), dentin...enzyme-linked immunosorbent assays (ELISAs) for quantitatively determining the levels of bone sialoprotein (BSP), osteopontin (OPN), dentin...synthesized as a chimeric protein, composed of three parts: dentin sialoprotein (DSP), dentin glycoprotein (DGP) and dentin phosphoprotein (DPP, also

Hierarchical structure and mechanical properties of remineralized dentin.

PubMed

Chen, Yi; Wang, Jianming; Sun, Jian; Mao, Caiyun; Wang, Wei; Pan, Haihua; Tang, Ruikang; Gu, Xinhua

2014-12-01

It is widely accepted that the mechanical properties of dentin are significantly determined by its hierarchical structure. The current correlation between the mechanical properties and the hierarchical structure was mainly established by studying altered forms of dentin, which limits the potential outcome of the research. In this study, dentins with three different hierarchical structures were obtained via two different remineralization procedures and at different remineralization stages: (1) a dentin structure with amorphous minerals incorporated into the collagen fibrils, (2) a dentin with crystallized nanominerals incorporated into the collagen fibrils, and (3) a dentin with an out-of-order mineral layer filling the collagen fibrils matrix. Nanoindentation tests were performed to investigate the mechanical behavior of the remineralized dentin slides. The results showed that the incorporation of the crystallized nanominerals into the acid-etched demineralized organic fibrils resulted in a remarkable improvement of the mechanical properties of the dentin. In contrast, for the other two structures, i.e. the amorphous minerals inside the collagen fibrils and the out-of-order mineral layer within the collagen fibrils matrix, the excellent mechanical properties of dentin could not be restored. Copyright © 2014 Elsevier Ltd. All rights reserved.

Co-distribution of cysteine cathepsins and matrix metalloproteases in human dentin.

PubMed

Scaffa, Polliana Mendes Candia; Breschi, Lorenzo; Mazzoni, Annalisa; Vidal, Cristina de Mattos Pimenta; Curci, Rosa; Apolonio, Fabianni; Gobbi, Pietro; Pashley, David; Tjäderhane, Leo; Tersariol, Ivarne Luis Dos Santos; Nascimento, Fábio Dupart; Carrilho, Marcela Rocha

2017-02-01

It has been hypothesized that cysteine cathepsins (CTs) along with matrix metalloproteases (MMPs) may work in conjunction in the proteolysis of mature dentin matrix. The aim of this study was to verify simultaneously the distribution and presence of cathepsins B (CT-B) and K (CT-K) in partially demineralized dentin; and further to evaluate the activity of CTs and MMPs in the same tissue. The distribution of CT-B and CT-K in sound human dentin was assessed by immunohistochemistry. A double-immunolabeling technique was used to identify, at once, the occurrence of those enzymes in dentin. Activities of CTs and MMPs in dentin extracts were evaluated spectrofluorometrically. In addition, in situ gelatinolytic activity of dentin was assayed by zymography. The results revealed the distribution of CT-B and CT-K along the dentin organic matrix and also indicated co-occurrence of MMPs and CTs in that tissue. The enzyme kinetics studies showed proteolytic activity in dentin extracts for both classes of proteases. Furthermore, it was observed that, at least for sound human dentin matrices, the activity of MMPs seems to be predominant over the CTs one. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microtensile bond strength of three simplified adhesive systems to caries-affected dentin.

PubMed

Scholtanus, J D; Purwanta, Kenny; Dogan, Nilgun; Kleverlaan, Cees J; Feilzer, Albert J

2010-08-01

The purpose of the study was to determine the microtensile bond strength of three different simplified adhesive systems to caries-affected dentin. Fifteen extracted human molars with primary carious lesions were ground flat until dentin was exposed. Soft caries-infected dentin was excavated with the help of caries detector dye. On the remaining hard dentin, a standardized smear layer was created by polishing with 600-grit SiC paper. Teeth were divided into three groups and treated with one of the three tested adhesives: Adper Scotchbond 1 XT (3M ESPE), a 2-step etch-andrinse adhesive, Clearfil S3 Bond (Kuraray), a 1-step self-etching or all-in-one adhesive, and Clearfil SE Bond (Kuraray), a 2-step self-etching adhesive. Five-mm-thick composite buildups (Z-250, 3M ESPE) were built and light cured. After water storage for 24 h at 37ºC, the bonded specimens were sectioned into bars (1.0 x 1.0 mm; n = 20 to 30). Microtensile bond strength of normal dentin specimens and caries-affected dentin specimens was measured in a universal testing machine (crosshead speed = 1 mm/min). Data were analyzed using two-way ANOVA and Tukey's post-hoc test (p < 0.05). No significant differences in bond strength values to normal dentin between the three adhesives were found. Adper Scotchbond 1 XT and Clearfil S3 Bond showed significantly lower bond strength values to caries-affected dentin. For Clearfil SE Bond, bond strength values to normal and caries-affected dentin were not significantly different. All the tested simplified adhesives showed similar bond strength values to normal dentin. For the tested 2-step etch-and-rinse adhesive and the all-in-one adhesive, the bond strength values to caries-affected dentin were lower than to normal dentin.

Grape seed extracts inhibit dentin matrix degradation by MMP-3

PubMed Central

Khaddam, Mayssam; Salmon, Benjamin; Le Denmat, Dominique; Tjaderhane, Leo; Menashi, Suzanne; Chaussain, Catherine; Rochefort, Gaël Y.; Boukpessi, Tchilalo

2014-01-01

Since Matrix metalloproteinases (MMPs) have been suggested to contribute to dentin caries progression, the hypothesis that MMP inhibition would affect the progression of dentin caries is clinically relevant. Grape seed extracts (GSE) have been previously reported to be natural inhibitors of MMPs. Objective: To evaluate the capacity of a GSE mouthrinse to prevent the degradation of demineralized dentin matrix by MMP-3 (stromelysin-1). Materials and Methods: Standardized blocks of dentin obtained from sound permanent teeth extracted for orthodontic reasons were demineralized with Ethylenediaminetetraacetic acid (EDTA) and pretreated either with (A) GSE (0.2% w/v), (B) amine fluoride (AmF) (20% w/v), (C) a mouthrinse which contains both, (D) placebo, (E) sodium fluoride (0.15 mg.ml−1), (F) PBS, (G) Chlorhexidine digluconate (CHX), or (H) zinc chloride (ZnCl2). The dentin blocks were then incubated with activated recombinant MMP-3. The supernatants were analyzed by Western Blot for several dentin matrix proteins known to be MMP-3 substrate. In parallel, scanning electron microscopy (SEM) was performed on resin replica of the dentin blocks. Results: Western blot analysis of the supernatants revealed that MMP-3 released from the dentin matrix small proteoglycans (decorin and biglycan) and dentin sialoprotein (DSP) in the AmF, sodium fluoride, PBS and placebo pretreated groups, but not in the GSE and mouthrinse pretreated groups. SEM examination of resin replica showed that the mouthrinse and its active components not only had an anti-MMP action but also modified the dentin surface accessibility. Conclusion: This study shows that GSE either alone or combined with AmF as in the evaluated mouthrinse limits dentin matrix degradation. This association may be promising to prevent the progression of caries within dentin. However, the procedure should be adapted to clinically relevant durations. PMID:25400590

Effect of a new desensitizing material on human dentin permeability.

PubMed

Rusin, Richard P; Agee, Kelli; Suchko, Michael; Pashley, David H

2010-06-01

Resin-modified glass ionomers (RMGI) have demonstrated clinical success providing immediate and long-term relief from root sensitivity. RMGIs have been recently introduced as paste-liquid systems for convenience of clinical usage. The objective of this study was to measure the ability of a new paste-liquid RMGI to reduce fluid flow through human dentin, compared to an established single-bottle nanofilled total etch resin adhesive indicated for root desensitization. Dentin permeability was measured on human crown sections on etched dentin, presenting a model for the exposed tubules typical of root sensitivity, and permitting measurement of the maximum permeability. In the first two groups, the etched dentin was coated with either the RMGI or adhesive, and permeability measured on the coated dentin. In a third group, a smear layer was created on the dentin with sandpaper, then the specimens were coated with the RMGI; permeability was measured on the smeared and coated dentin. Specimens from each group were sectioned and examined via scanning electron microscopy (SEM). Both the resin adhesive and the new paste-liquid RMGI protective material significantly reduced fluid flow through dentin, and exhibited excellent seal on dentin with either open tubules or smear-layer occluded tubules. The RMGI infiltrated the smear layer with resin during placement, penetrated dentin tubules, and formed resin tags. The RMGI was equivalent to the adhesive in its ability to reduce fluid flow and seal dentin. It is therefore concluded that the new RMGI and the adhesive show the potential to offer excellent sensitivity relief on exposed root dentin. Copyright (c) 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Influence of depositional environment in fossil teeth: a micro-XRF and XAFS study

NASA Astrophysics Data System (ADS)

Zougrou, I. M.; Katsikini, M.; Pinakidou, F.; Papadopoulou, L.; Tsoukala, E.; Paloura, E. C.

2014-04-01

The formation of metal-rich phases during the fossilization of vertebrate fossil teeth, recovered from various deposition environments in northern Greece, is studied by means of synchrotron radiation X-ray fluorescence (SR-XRF) as well as Fe and Mn K edge X-ray absorption fine structure (XAFS) spectroscopy. XRF line-scans from the samples' cross-sections revealed different contamination paths for Mn and Fe. The two-dimensional XRF maps illustrate the spatial distribution of P, Ca, Mn and Fe as well as the precipitation of Fe-rich phases in cementum, dentin and dentinal tubules. Goethite, lepidocrocite and ferrihydrite were detected in the samples' cross-section by means of Fe K edge EXAFS spectroscopy. Moreover the Fe and Mn K edge EXAFS revealed the presence of vivianite and birnessite (MnO2) on the external surface of two samples.

Influence of Immediate Dentin Sealing on the Shear Bond Strength of Pressed Ceramic Luted to Dentin with Self-Etch Resin Cement

PubMed Central

Dalby, Robert; Ellakwa, Ayman; Millar, Brian; Martin, F. Elizabeth

2012-01-01

Objectives. To examine the effect of immediate dentin sealing (IDS), with dentin bonding agents (DBAs) applied to freshly cut dentin, on the shear bond strength of etched pressed ceramic luted to dentin with RelyX Unicem (RXU) cement. Method. Eighty extracted noncarious third molars were ground flat to expose the occlusal dentin surfaces. The teeth were randomly allocated to five groups (A to E) of sixteen teeth each. Groups A to D were allocated a dentin bonding agent (Optibond FL, One Coat Bond, Single Bond, or Go!) that was applied to the dentin surface to mimic the clinical procedure of IDS. These specimen groups then had etched glass ceramic discs (Authentic) luted to the sealed dentin surface using RXU. Group E (control) had etched glass ceramic discs luted to the dentin surface (without a dentin bonding agent) using RXU following the manufacturer's instructions. All specimens were stored for one week in distilled water at room temperature and then shear stressed at a constant cross-head speed of 1 mm per minute until failure. Statistical analysis was performed by ANOVA followed by post hoc Tukey HSD method (P < 0.05) applied for multiple paired comparisons. Results. The shear bond strength results for group A to E ranged from 6.94 ± 1.53 to 10.03 ± 3.50 MPa. One-way ANOVA demonstrated a difference (P < 0.05) between the groups tested and the Tukey HSD demonstrated a significant (P < 0.05) difference between the shear bond strength (SBS) of Optibond FL (Group A) and Go! (Group D). There was no statistical difference (P > 0.05) in the SBS between the test groups (A–D) or the control (group E). Conclusion. IDS using the dentin bonding agents tested does not statistically (P > 0.05) affect the shear bond strength of etched pressed ceramic luted to dentin with RXU when compared to the control. PMID:22287963

Poly(amido amine) and calcium phosphate nanocomposite remineralization of dentin in acidic solution without calcium phosphate ions.

PubMed

Liang, Kunneng; Zhou, Han; Weir, Michael D; Bao, Chongyun; Reynolds, Mark A; Zhou, Xuedong; Li, Jiyao; Xu, Hockin H K

2017-07-01

Patients with dry mouth often have an acidic oral environment lacking saliva that provides calcium (Ca) and phosphate (P) ions. However, there has been no study on dentin remineralization by placing samples in an acidic solution without Ca and P ions. Previous studies used saliva-like solutions with neutral pH and Ca and P ions. Therefore, the objective of this study was to investigate a novel method of combining poly(amido amine) (PAMAM) with a composite of nanoparticles of amorphous calcium phosphate (NACP) on dentin remineralization in an acidic solution without Ca and P ions for the first time. Demineralized dentin specimens were tested into four groups: (1) dentin control, (2) dentin coated with PAMAM, (3) dentin with NACP nanocomposite, (4) dentin with PAMAM plus NACP composite. Specimens were treated with lactic acid at pH 4 without initial Ca and P ions for 21 days. Acid neutralization and Ca and P ion concentrations were measured. Dentin specimens were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and hardness testing vs. remineralization efficacy. NACP composite had mechanical properties similar to commercial control composites (p>0.1). NACP composite neutralized acid and released Ca and P ions. PAMAM alone failed to induce dentin remineralization. NACP alone achieved mild remineralization and slightly increased dentin hardness at 21days (p>0.1). In contrast, the PAMAM+NACP nanocomposite method in acid solution without initial Ca and P ions greatly remineralized the pre-demineralized dentin, restoring its hardness to approach that of healthy dentin (p>0.1). Dentin remineralization via PAMAM+NACP in pH 4 acid without initial Ca and P ions was demonstrated for the first time, when conventional methods such as PAMAM did not work. The novel PAMAM+NACP nanocomposite method is promising to protect tooth structures, especially for patients with reduced saliva to inhibit caries. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Morphological Analysis of Dentin Surface after Conditioning with Two Different methods: Chemical and Mechanical.

PubMed

Rafael, Caroline Freitas; Quinelato, Valquíria; Morsch, Carolina Schaffer; DeDeus, Gustavo; Reis, Claudia Mendonca

2016-01-01

Alternative pretreatment strategies of dentin and adhesionare constantly being developed and studied with the goal of improving the adhesion of resin restorative materials with this tissue. The objectives of the present study were to evaluate the ability of airborne-particle abrasion (APA) with aluminum oxide on dentin to remove the smear layer and the effects produced on the dentin microstructure. The phosphoric acid (PA) was used for a comparison. For that, 20 human third molars were randomly allocated into two experimental groups, according to the dentin pretreatment method used: G1 (N = 10) - PA, G2 (N = 10) -APA. For dentin surface analyses, an environmental scanning electron microscope (ESEM) was employed to observe dentin surfaces before and after the procedures. Before pretreatment, the specimens of both groups were smear covered. After pretreatment, the G1 images revealed dentin tubule orifices opened, enlarged and some erosive effects. (G2) exposed tubule orifices without enlargement, but crack-like alterations were observed on the surfaces. In this way, APA with aluminum oxide was able to remove the smear layer. The influences of the dentin roughness on adhesion and the consequences on dentin integrity and hardness need further investigations. A good conditioning of the dentin before cementation is necessary in order to obtain a satisfactory rehabilitation in adhesive dentistry. So, it is necessary to know all methods to do it.

Evaluating EDTA as a substitute for phosphoric acid-etching of enamel and dentin.

PubMed

Imbery, Terence A; Kennedy, Matthew; Janus, Charles; Moon, Peter C

2012-01-01

Matrix metalloproteinases (MMPs) are proteolytic enzymes released when dentin is acid-etched. The enzymes are capable of destroying unprotected collagen fibrils that are not encapsulated by the dentin adhesive. Chlorhexidine applied after etching inhibits the activation of released MMPs, whereas neutral ethylenediamine tetra-acetic acid (EDTA) prevents the release of MMPs. The purpose of this study was to determine if conditioning enamel and dentin with EDTA can be a substitute for treating acid-etching enamel and dentin with chlorhexidine. A column of composite resin was bonded to enamel and dentin after conditioning. Shear bond strengths were evaluated after 48 hours and after accelerated aging for three hours in 12% sodium hypochlorite. Shear bond strengths ranged from 15.6 MP a for accelerated aged EDTA enamel specimens to 26.8 MPa for dentin conditioned with EDTA and tested after 48 hours. A three-way ANOVA and a Tukey HSD test found statistically significant differences among the eight groups and the three independent variables (P < 0.05). EDTA was successfully substituted for phosphoric acid-etched enamel and dentin treated with chlorhexidine. Interactions of conditioning agent and aging were significant for dentin but not for enamel. In an effort to reduce the detrimental effects of MMPs, conditioning enamel and dentin with EDTA is an alternative to treating acid-etched dentin and enamel with chlorhexidine.

Zinc-Containing Restorations Create Amorphous Biogenic Apatite at the Carious Dentin Interface: A X-Ray Diffraction (XRD) Crystal Lattice Analysis.

PubMed

Toledano, Manuel; Aguilera, Fátima S; López-López, Modesto T; Osorio, Estrella; Toledano-Osorio, Manuel; Osorio, Raquel

2016-10-01

The aim of this research was to assess the ability of amalgam restorations to induce amorphous mineral precipitation at the caries-affected dentin substrate. Sound and caries-affected dentin surfaces were subjected to both Zn-free and Zn-containing dental amalgam restorations. Specimens were submitted to thermocycling (100,000 cycles/5°C-55°C, 3 months). Dentin surfaces were studied by atomic force microscopy (nanoroughness), X-ray diffraction, field emission scanning electron microscopy, and energy-dispersive analysis, for physical and morphological surface characterization. Zn-containing amalgam placement reduced crystallinity, crystallite size, and grain size of calcium phosphate crystallites at the dentin surface. Both microstrain and nanoroughness were augmented in caries-affected dentin restored with Zn-containing amalgams. Caries-affected dentin showed the shortest mineral crystallites (11.04 nm), when Zn-containing amalgams were used for restorations, probably leading to a decrease of mechanical properties which might favor crack propagation and deformation. Sound dentin restored with Zn-free amalgams exhibited a substantial increase in length of grain particles (12.44 nm) embedded into dentin crystallites. Zn-containing amalgam placement creates dentin mineralization and the resultant mineral was amorphous in nature. Amorphous calcium phosphate provides a local ion-rich environment, which is considered favorable for in situ generation of prenucleation clusters, promotong further dentin remineralization.

The effect of dentinal stimulation on pulp nerve function and pulp morphology in the dog.

PubMed

Hirvonen, T J; Närhi, M V

1986-11-01

The effect of dentinal stimulation on pulpal nerve responses and pulp morphology has been studied in the dog. Canine tooth (n = 25) dentin was stimulated by drilling, probing, and air-blasting for from two to five hours. Acid-etching was used to open dentinal tubules. All test teeth showed disruption of the odontoblast layer and its separation from the predentin; also, dislocation of odontoblast nuclei into dentinal tubules was found in most cases. Single-fiber (n = 14, conduction velocity = 24.3 +/- 7.4 (SD) m/s) recordings of the responses of canine tooth pulpal nerves to dentinal stimulation were made in ten of the stimulated teeth. No changes in the sensitivity of the nerves to dentinal stimulation could be detected. It is concluded that pulpal nerve function and morphological changes of the pulp are not clearly correlated. The condition of the dentin surface seems to be the important factor.

Deformation behavior of human dentin in liquid nitrogen: a diametral compression test.

PubMed

Zaytsev, Dmitry; Panfilov, Peter

2014-09-01

Contribution of the collagen fibers into the plasticity of human dentin is considered. Mechanical testing of dentin at low temperature allows excluding the plastic response of its organic matrix. Therefore, deformation and fracture behavior of the dentin samples under diametral compression at room temperature and liquid nitrogen temperature are compared. At 77K dentin behaves like almost brittle material: it is deformed exclusively in the elastic regime and it fails due to growth of the sole crack. On the contrary, dentin demonstrates the ductile response at 300K. There are both elastic and plastic contributions in the deformation of dentin samples. Multiple cracking and crack tip blunting precede the failure of samples. Organic phase plays an important role in fracture of dentin: plasticity of the collagen fibers could inhibit the crack growth. Copyright © 2014 Elsevier B.V. All rights reserved.

Evaluation of tartar control dentifrices in in vitro models of dentin sensitivity.

PubMed

Mason, S; Levan, A; Crawford, R; Fisher, S; Gaffar, A

1991-01-01

The effects of anticalculus dentifrices were compared with other commercially available dentifrices in in vitro models of dentin sensitivity. Changes in the hydraulic conductance of dentin discs were measured with and without a smear layer before and after treatment and also after a post-treatment acid etch. The capacity of dentifrices to occlude open dentinal tubules in vitro was also assessed by scanning electron microscopy (SEM). There was good correlation (R = 0.98) between our test and values reported in the literature. Tartar control dentifrices gave reductions in fluid flow rates through the dentin discs comparable to those obtained with Promise, Sensodyne, Thermodent and Denquel. Additionally, tartar control dentifrices did not remove microcrystalline debris (smear layers) from the surfaces of dentin in vitro. These results were confirmed by SEM. Thus, according to the hydrodynamic theory of dentin sensitivity, these in vitro results suggest that pyrophosphate-containing dentifrices should reduce dentinal sensitivity.

The early Pleistocene deciduous hominid molar FS-72 from the Sangiran Dome of Java, Indonesia: A taxonomic reappraisal based on its comparative endostructural characterization.

PubMed

Zanolli, Clément; Grine, Frederick E; Kullmer, Ottmar; Schrenk, Friedemann; Macchiarelli, Roberto

2015-08-01

Among the ten fossil hominid deciduous teeth reported so far from the Pleistocene sediments of the Sangiran Dome of Java are two isolated lower second molars: specimens PCG.2 from the Kabuh Formation and FS-72 from the Pucangan Formation. While PCG.2 appears to be certainly attributable to Homo erectus, FS-72 is somewhat more problematic, even though it is commonly listed within the Indonesian H. erectus hypodigm. Largely because of its large size, it was originally attributed to Meganthropus paleojavanicus. Subsequent study highlighted a set of metric and nonmetric crown features also found in Australopith and African early Homo (notably H. habilis) homologues. An additional problem with the taxonomic assignment of isolated teeth from the Pleistocene of Java is the presence of Pongo in these same deposits. To assess the taxonomic affinity of FS-72, we investigated its inner structure (tissue proportions and enamel-dentine junction morphology) by using techniques of 2-3D virtual imaging coupled with geometric morphometric analyses. The results show that FS-72 has thinner enamel compared to fossil and recent humans and that its topographic repartition more closely follows the pongine pattern. It also exhibits a Pongo-like elongated morphology of the enamel-dentine junction, with proportionally lower and mesiodistally spaced dentine horns. Given the morphological and metric similarities between fossil orangutan and H. erectus molars, we tested the hypothesis that its internal morphology more closely resembles the patterns evinced by PCG.2 and modern humans than Pongo. Accordingly, we consider that FS-72 more likely represents a dm2 of Pongo rather than Homo. © 2015 Wiley Periodicals, Inc.

Comparison of gray mineral trioxide aggregate and diluted formocresol in pulpotomized primary molars: a 6- to 24-month observation.

PubMed

Sushynski, John M; Zealand, Cameron M; Botero, Tatiana M; Boynton, James R; Majewski, Robert F; Shelburne, Charles E; Hu, Jan Chingchun

2012-01-01

The purpose of this multisite, multioperator, prospective, randomized, controlled clinical trial was to evaluate 2-year outcomes of diluted formocresol (DFC) compared to gray mineral trioxide aggregate (GMTA) as pulpotomy medicaments. Following the standard pulpotomy procedure, the pulp stumps of 252 primary molars in 168 healthy children were randomly covered with GMTA or DFC. Pulp chambers were filled with Intermediate Restorative Material (IRM(®)) and teeth were restored with stainless steel crowns. At each follow-up appointment, the clinical status of the treated tooth was assessed and radiographs were taken. A total of 694 clinical and radiographic evaluations were analyzed. Gender, study site, arch type, and tooth type did not influence treatment outcome. At the combined 6- to 24-month follow-up, clinical success in the DFC group was no different than for the GMTA group. Radiographically, a significantly lower success rate was found in the DFC group vs the MTA group at all time points (P<.01). Dentin bridge formation was observed at a significantly higher frequency among the GMTA group (P<.01), while internal root resorption was observed at a higher frequency in the DFC group (P<.01). At the combined 6- to 24-month follow-up, gray mineral trioxide aggregate demonstrated significantly better radiographic outcomes vs diluted formocresol as pulpotomy medicaments.

Caries-removal effectiveness of a papain-based chemo-mechanical agent: A quantitative micro-CT study.

PubMed

Neves, Aline A; Lourenço, Roseane A; Alves, Haimon D; Lopes, Ricardo T; Primo, Laura G

2015-01-01

The aim of this study was to access the effectiveness and specificity of a papain-based chemo-mechanical caries-removal agent in providing minimum residual caries after cavity preparation. In order to do it, extracted carious molars were selected and scanned in a micro-CT before and after caries-removal procedures with the papain-based gel. Similar parameters for acquisition and reconstruction of the image stacks were used between the scans. After classification of the dentin substrate based on mineral density intervals and establishment of a carious tissue threshold, volumetric parameters related to effectiveness (mineral density of removed dentin volume and residual dentin tissue) and specificity (relation between carious dentin in removed volume and initial caries) of this caries-removal agent were obtained. In general, removed dentin volume was similar or higher than the initial carious volume, indicating that the method was able to effectively remove dentin tissue. Samples with an almost perfect accuracy in carious dentin removal also showed an increased removal of caries-affected tissue. On the contrary, less or no affected dentin was removed in samples where some carious tissue was left in residual dentin. Mineral density values in residual dentin were always higher or similar to the threshold for mineral density values in carious dentin. In conclusion, the papain-based gel was effective in removing carious dentin up to a conservative in vitro threshold. Lesion characteristics, such as activity and morphology of enamel lesion, may also influence caries-removal properties of the method. © Wiley Periodicals, Inc.

The interrelationship of microstructure and hardness of human coronal dentin using reference point indentation technique and micro-Raman spectroscopy.

PubMed

Seyedmahmoud, Rasoul; McGuire, Jacob D; Wang, Yong; Thiagarajan, Ganesh; Walker, Mary P

2017-10-01

The aim of this paper is to determine the interrelationship between the microstructure - in terms of chemical composition and crystallinity - to the microhardness of coronal dentin. Dentin microhardness was tested by a novel reference point indenter and compared to the traditional Knoop hardness method. Micro-Raman spectroscopy was used to determine the chemical composition and crystallinity of dentin. From the occlusal groove to the border of the coronal pulp chamber, dentin hardness decreased from superficial dentin (SD) to deep dentin (DD). Mineral/organic matrix ratios (phosphate/CH and phosphate/amide I) also decreased from SD to DD; however, this change was significant (P<0.05) in the phosphate/amide I ratio only. The phosphate/carbonate ratio decreased significantly by varying position from SD to DD. The degree of the crystallinity, as measured by the full width at half maximum (FWHM) of the peak at 960cm -1 , decreased significantly going from superficial to deep dentin. For the first time, the interrelationship between the microstructure and the mechanical properties of coronal dentin was determined by using the novel reference point indentation technique and micro-Raman spectroscopy. We hypothesize that the decrease in hardness from superficial to deep dentin can potentially be explained by decreased mineral content and increased carbonate content, which is also associated with decreased crystallinity. Collectively, there is a positive association between dentin hardness and mineral content and a negative association between dentin hardness and carbonate content. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Nanomechanical properties of biochemically modified dentin bonded interfaces

PubMed Central

dos Santos, Paulo H; Karol, Sachin; Bedran-Russo, Ana Karina B

2014-01-01

Summary The effect of biomodification of dentin matrices using collagen cross-linkers, glutaraldehyde (GD) and grape seed extract (GSE), on the reduced modulus of elasticity (Er) and nanohardness (H) of the hybrid layer and underlying dentin was investigated at the dentin-resin bonded interface. The coronal dentin of nine molars were exposed and divided into groups: 5% GD, 6.5% GSE and control. Control samples were etched, bonded with Adper Single Bond Plus and Premise composite. GD and GSE were applied for 1 hour prior to bonding procedures. After 24 hours, samples were sectioned, and resin-dentin beams were either kept in distilled water or exposed to collagenase treatment for 24 hours. Nano-indentations were performed at the hybrid layer and underlying dentin. GD and GSE treatment increased the Er and H of resin-dentin interface structures when compared to the control group (p < 0.05), particularly the hybrid layer, and may be a promising novel approach to strengthen the dentin-resin bonded interface structures when using these adhesive system and resin-based composite. PMID:21058972

Prevalence of dentine hypersensitivity: A cross-sectional study in rural Punjabi Indians

PubMed Central

Dhaliwal, Jagjit Singh; Palwankar, Pooja; Khinda, Paramjit K.; Sodhi, Sachinjeet K.

2012-01-01

Aims and Objectives: To study the prevalence of dentine hypersensitivity and related risk factors in rural population of Punjab, India. Materials and Methods: A total of 650 subjects reporting dentine sensitivity were included in the study comprising of 270 males and 380 females. All the subjects completed an interview and the subjects reporting dentine hypersensitivity were examined further using air syringe to put a blast of air to confirm the diagnosis of dentine hypersensitivity. Periodontal attachment loss and gingival recession of all the sensitive teeth were examined and recorded. Results: The prevalence of dentine hypersensitivity was 25% in the oral test. The subjects receiving the treatment of hypersensitivity were only 15.1%. The older group in the 50-59 years had the highest number (98%) of subjects with dentine hypersensitivity. Most commonly affected teeth were mandibular incisors. The other factors related to dentine hypersensitivity were the socioeconomic status, lower education level, and access to dental care. The periodontal factors related to hypersensitivity were gingival recession and poor oral hygiene. Conclusions: The prevalence of dentine hypersensitivity was 25% in the rural population of Punjab. PMID:23162341

Unique behaviour of dinitrogen-bridged dimolybdenum complexes bearing pincer ligand towards catalytic formation of ammonia.

PubMed

Tanaka, Hiromasa; Arashiba, Kazuya; Kuriyama, Shogo; Sasada, Akira; Nakajima, Kazunari; Yoshizawa, Kazunari; Nishibayashi, Yoshiaki

2014-04-28

It is vital to design effective nitrogen fixation systems that operate under mild conditions, and to this end we recently reported an example of the catalytic formation of ammonia using a dinitrogen-bridged dimolybdenum complex bearing a pincer ligand, where up to twenty three equivalents of ammonia were produced based on the catalyst. Here we study the origin of the catalytic behaviour of the dinitrogen-bridged dimolybdenum complex bearing the pincer ligand with density functional theory calculations, based on stoichiometric and catalytic formation of ammonia from molecular dinitrogen under ambient conditions. Comparison of di- and mono-molybdenum systems shows that the dinitrogen-bridged dimolybdenum core structure plays a critical role in the protonation of the coordinated molecular dinitrogen in the catalytic cycle.

Long-Term Bond Strength of Two Benzalkonium Chloride-Modified Adhesive Systems to Eroded Dentin

PubMed Central

Lussi, Adrian; Peutzfeldt, Anne

2017-01-01

This study investigated the effect of benzalkonium chloride (BAC) modification of two adhesive systems on long-term bond strength to normal and artificially eroded dentin. A total of 128 extracted human molars were sectioned and the buccal and oral surfaces of each molar were ground until the dentin. One half was left untreated (normal dentin) while the other half underwent artificial erosion. Resin composite was bonded to the buccal or oral surface following treatment with Adper Scotchbond 1XT or OptiBond FL without or with 1% BAC incorporation. Shear bond strength (SBS) was measured after 24 h (100% humidity, 37°C) or 1 year (tap water, 37°C). SBS results were statistically analyzed (α = 0.05). SBS was significantly lower to artificially eroded dentin than to normal dentin (p < 0.001). Storage for 1 year had no effect on SBS to normal dentin but led to a significant decrease in SBS to artificially eroded dentin (p < 0.001). BAC incorporation decreased the 24 h SBS to normal dentin (p = 0.018), increased the 24 h SBS to eroded dentin (p = 0.001), and had no effect on the 1-year SBS for either substrate. Consequently, BAC incorporation did not improve bond durability. PMID:28875148

Effect of dentin etching and chlorhexidine application on metalloproteinase-mediated collagen degradation

PubMed Central

Raquel, Osorio; Mónica, Yamauti; Estrella, Osorio; Estrella, Ruiz-Requena María; David, Pashley; Franklin, Tay; Manuel, Toledano

2013-01-01

Dentin matrix metalloproteinases (MMPs) are involved in collagen degradation of resin-dentin interfaces. This study evaluated if collagen degradation can be prevented by chlorhexidine after different dentin demineralization procedures. Human dentin demineralization was performed with phosphoric acid (PA), EDTA, or acidic monomers (ClearfilSEBond and XENOV). Specimens were stored (24 h, 1 wk or 3 wk) in the presence or absence of chlorhexidine. In half of the groups, active MMP-2 was incorporated into the storing solution. C-terminal telopeptide determination (ICTP) was performed in the supernatants. Collagen degradation was higher in PA and EDTA-demineralized dentin. Chlorhexidine reduced collagen degradation in these groups only for 24 h. When dentin was demineralized with SEBond or Xeno, collagen degradation was reduced up to 30%, but addition of exogenous MMP-2 significantly increased collagen degradation. In self-etchant treated dentin the inhibitory effect of chlorhexidine on MMPs lasted up to 3 wk. Treating dentin with EDTA, PA or self-etching agents produces enough demineralization to permit cleavage of the exposed collagen. Monomers infiltration may exert protection on demineralized collagen, probably through immobilization of MMPs. The partial inhibitory action of CHX on MMP activity produced by self-etching adhesives was prolonged compared to the short-acting in PA or EDTA-treated dentin. PMID:21244516

Hydromechanics in dentine: role of dentinal tubules and hydrostatic pressure on mechanical stress-strain distribution.

PubMed

Kishen, A; Vedantam, S

2007-10-01

This investigation is to understand the role of free water in the dentinal tubules on the mechanical integrity of bulk dentine. Three different experiments were conducted in this study. In experiment 1, three-dimensional models of dentine with gradient elastic modulus, homogenous elastic modulus, and with and without hydrostatic pressure were simulated using the finite element method. Static compressive loads of 15, 50 and 100 N were applied and the distribution of the principal stresses, von Mises stresses, and strains in loading direction were determined. In experiment 2, experimental compression testing of fully hydrated and partially dehydrated dentine (21 degrees C for 72 h) was conducted using a Universal testing machine. In experiment 3, Fourier transform infrared spectroscopic analysis of hydrated and partially dehydrated dentine was carried out. The finite element analysis revealed that the dentine model with simulated hydrostatic pressure displayed residual tensile stresses and strains in the inner region adjacent to the root canal. When external compressive loads were applied to the model, the residual stresses and strains counteracted the applied loads. Similarly the hydrated specimens subjected to experimental compression loads showed greater toughness when compared to the partially dehydrated specimens. The stress at fracture was significantly higher in partially dehydrated specimens (p=0.014), while the strain at fracture was significantly higher in hydrated dentine specimens (p=0.037). These experiments highlighted the distinct role of free water in the dentinal tubules and hydrostatic pressure on the stress-strain distribution within the bulk dentine.

Demonstration of a focused ion-beam cross-sectioning technique for ultrastructural examination of resin-dentin interfaces.

PubMed

Van Meerbeek, B; Conn, L J; Duke, E S; Schraub, D; Ghafghaichi, F

1995-03-01

focused ion-beam (FIB) etching, commonly used as a cross-sectioning technique for failure analysis of semiconductor devices, has recently been applied to biological tissues to expose their ultrastructure for examination. It was the aim of this investigation to determine the practical utility of FIB to cross-section resin-dentin interfaces in order to morphologically evaluate the completeness of resin penetration into the exposed collagen scaffold at the resin-dentin bond interface. Two representative commercially available dentin adhesive systems were bonded to mid-coronal dentin. After appropriate fixation and dehydration of the resin-bonded dentin samples, a scanned focused ion-beam of a few tens of nano-meters in diameter was used to cross=section the resin-dentin interface. Examination of the interfacial ultrastructure was accomplished using a field-emission SEM. Results indicate possible artifact production at the cross-sectioned interface, hiding its actual ultrastructure, probably due to a heat-effect with possible recrystallization. Further studies of FIB are needed to optimize its usefulness for resin-dentin interface examinations and other biological tissue applications. Complete resin saturation of the demineralized dentin surface-layer has been claimed to be the key factor for a long-lasting resin-dentin bond. A "clean" artifact-free micro-cross-sectioning technique may provide indisputable ultra-structural information about the depth of resin penetration into the demineralized zone. Such a test would be useful in the development of dentin adhesive systems.

Efficacy of calcium oxide and calcium hydroxide nanoparticles on the elimination of Enterococcus faecalis in human root dentin.

PubMed

Louwakul, Phumisak; Saelo, Attapon; Khemaleelakul, Saengusa

2017-04-01

The objective of this study was to compare the antibacterial effect of calcium oxide nanoparticles (CONPs) and calcium hydroxide nanoparticles (CHNPs) against Enterococcus faecalis in a dentinal block model. E. faecalis strain JCM 7783 was introduced into dentinal tubules of semicylindrical dentin specimens by centrifugation and incubated for 1 week. Fifty microliters of CONPs or CHNPs was placed on the root canal side of the infected dentin specimens. The specimens were then incubated in aerobic condition at 37 °C and 100 % relative humidity for 1 week. The treated dentin specimens were subjected to fluorescent staining and confocal laser scanning microscopy (CLSM) to analyze the proportions of non-vital and vital bacterial cells inside the dentinal tubules. Scanning electron microscopy (SEM) was used to confirm the effect of the medicaments on the bacteria in the dentinal tubules. Calcium oxide (CO) and calcium hydroxide (CH) were used as controls. Based on the CLSM and SEM analyses, CHNPs were more efficient than CONPs in the elimination of the bacteria in the dentinal tubules. CONPs significantly killed more E. faecalis than CO and CH (P < .05). Neither CO nor CH was able to kill the bacteria. CHNPs were more effective than CONPs in the elimination of E. faecalis in dentinal tubules. CHNPs are effective nanoparticles in killing endodontic bacteria present in dentinal tubules. They have potential as an intracanal medicament, which may be beneficial in root canal therapy.

Review of methyl methacrylate (MMA)/tributylborane (TBB)-initiated resin adhesive to dentin.

PubMed

Taira, Yohsuke; Imai, Yohji

2014-01-01

This review, focusing mainly on research related to methyl methacrylate/tributylborane (MMA/TBB) resin, presents the early history of dentin bonding and MMA/TBB adhesive resin, followed by characteristics of resin bonding to dentin. Bond strengths of MMA/TBB adhesive resin to different adherends were discussed and compared with other bonding systems. Factors affecting bond strength (such as conditioners, primers, and medicaments used for dental treatment), bonding mechanism, and polymerization characteristics of MMA/TBB resin were also discussed. This review further reveals the unique adhesion features between MMA/TBB resin and dentin: in addition to monomer diffusion into the demineralized dentin surface, graft polymerization of MMA onto dentin collagen and interfacial initiation of polymerization at the resin-dentin interface provide the key bonding mechanisms.

Potential role of surface wettability on the long-term stability of dentin bonds after surface biomodification

PubMed Central

Leme, Ariene A.; Vidal, Cristina M. P.; Hassan, Lina Saleh; Bedran-Russo, Ana K.

2015-01-01

Degradation of the adhesive interface contributes to the failure of resin composite restorations. The hydrophilicity of the dentin matrix during and after bonding procedures may result in an adhesive interface that is more prone to degradation over time. This study assessed the effect of chemical modification of dentin matrix on the wettability and the long-term reduced modulus of elasticity (Er) of the adhesive interfaces. Human molars were divided into groups according to the priming solutions: distilled water (control), 6.5% Proanthocyanidin-rich grape seed extract (PACs), 5.75% 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride/1.4% n-hydroxysuccinimide (EDC/NHS) and 5% Glutaraldehyde (GA). The water-surface contact angle was verified before and after chemical modification of the dentin matrix. The demineralized dentin surface was treated with the priming solutions and restored with One Step Plus (OS) and Single Bond Plus (SB) and resin composite. The Er of the adhesive, hybrid layer and underlying dentin was evaluated after 24 h and 30 months in artificial saliva. The dentin hydrophilicity significantly decreased after application of the priming solutions. Aging significantly decreased the Er in the hybrid layer and underlying dentin of control groups. The Er of GA groups remained stable over time at the hybrid layer and underlying dentin. Significant higher Er was observed for PACs and EDC/NHS groups at the hybrid layer after 24 h. The decreased hydrophilicity of the modified dentin matrix likely influence the immediate mechanical properties of the hybrid layer. Dentin biomodification prevented substantial aging at the hybrid layer and underlying dentin after 30 months storage. PMID:25869721

Effect of Lesion Baseline Severity and Mineral Distribution on Remineralization and Progression of Human and Bovine Dentin Caries Lesions.

PubMed

Lippert, Frank; Churchley, David; Lynch, Richard J

2015-01-01

The aims of this laboratory study were to compare the effects of lesion baseline severity, mineral distribution and substrate on remineralization and progression of caries lesions created in root dentin. Lesions were formed in dentin specimens prepared from human and bovine dentin using three protocols, each utilizing three demineralization periods to create lesions of different mineral distributions (subsurface, moderate softening, extreme softening) and severity within each lesion type. Lesions were then either remineralized or demineralized further and analyzed using transverse microradiography. At lesion baseline, no differences were found between human and bovine dentin for integrated mineral loss (x0394;Z). Differences in mineral distribution between lesion types were apparent. Human dentin lesions were more prone to secondary demineralization (x0394;x0394;Z) than bovine dentin lesions, although there were no differences in x0394;L. Likewise, smaller lesions were more susceptible to secondary demineralization than larger ones. Subsurface lesions were more acid-resistant than moderately and extremely softened lesions. After remineralization, differences between human and bovine dentin lesions were not apparent for x0394;x0394;Z although bovine dentin lesions showed greater reduction in lesion depth L. For lesion types, responsiveness to remineralization (x0394;x0394;Z) was in the order extremely softened>moderately softened>subsurface. More demineralized lesions exhibited greater remineralization than shallower ones. In summary, some differences exist between human and bovine dentin and their relative responsiveness to de- and remineralization. These differences, however, were overshadowed by the effects of lesion baseline mineral distribution and severity. Thus, bovine dentin appears to be a suitable substitute for human dentin in mechanistic root caries studies. © 2015 S. Karger AG, Basel.

The effect of 8.25% sodium hypochlorite on dental pulp dissolution and dentin flexural strength and modulus.

PubMed

Cullen, James K T; Wealleans, James A; Kirkpatrick, Timothy C; Yaccino, John M

2015-06-01

The purpose of this study was to evaluate the effect of various concentrations of sodium hypochlorite (NaOCl), including 8.25%, on dental pulp dissolution and dentin flexural strength and modulus. Sixty dental pulp samples and 55 plane parallel dentin bars were retrieved from extracted human teeth. Five test groups (n = 10) were formed consisting of a pulp sample and dentin bar immersed in various NaOCl solutions. The negative control group (n = 5) consisted of pulp samples and dentin bars immersed in saline. The positive control group (n = 5) consisted of pulp samples immersed in 8.25% NaOCl without a dentin bar. Every 6 minutes for 1 hour, the solutions were refreshed. The dentin bars were tested for flexural strength and modulus with a 3-point bend test. The time until total pulp dissolution and any changes in dentin bar flexural strength and modulus for the different NaOCl solutions were statistically analyzed. An increase in NaOCl concentration showed a highly significant decrease in pulp dissolution time. The pulp dissolution property of 8.25% NaOCl was significantly faster than any other tested concentration of NaOCl. The presence of dentin did not have a significant effect on the dissolution capacity of NaOCl if the solutions were refreshed. NaOCl concentration did not have a statistically significant effect on dentin flexural strength or modulus. Dilution of NaOCl decreases its pulp dissolution capacity. Refreshing the solution is essential to counteract the effects of dentin. In this study, NaOCl did not have a significant effect on dentin flexural strength or modulus. Published by Elsevier Inc.

Biomechanical studies on the effect of iatrogenic dentin removal on vertical root fractures.

PubMed

Ossareh, A; Rosentritt, M; Kishen, A

2018-01-01

The aim of this study was to understand the mechanism by which iatrogenic root dentin removal influences radicular stress distribution and subsequently affects the resistance to vertical root fractures (VRF) in endodontically treated teeth. The experiments were conducted in two phases. Phase 1: freshly extracted premolar teeth maintained in phosphate-buffered saline were instrumented to simulate three different degrees of dentin removal, designated as low, medium, and extreme groups. Micro-Ct analyzes were performed to quantitatively determine: (a) the amount of dentin removed, (b) the remaining dentin volume, and (c) the moment of inertia of root dentin. The specimens were then subjected to thermomechanical cycling and continuous loading to determine (a) the mechanical load to fracture and (b) dentin microcracking (fractography) using scanning electron microscopy. Phase 2: Finite element analysis was used to evaluate the influence of dentin removal on the stress distribution pattern in root dentin. The data obtained were analyzed using one-way ANOVA and Tukey's post hoc test ( P < 0.05). Phase 1: A significantly greater volume of dentin was removed from teeth in extreme group when compared to low group ( P < 0.01). The mechanical analysis showed that the load to fracture was significantly lower in teeth from extreme group ( P < 0.05). A linear relationship was observed between the moment of inertia and load to fracture in all experimental groups ( R 2 = 0.52). Fractography showed that most microcracks were initiated from the root canal walls in extreme group. Phase 2: The numerical analysis showed that the radicular stress distribution increased apically and buccolingually with greater degree of root canal dentin removal. The combined experimental/numerical analyses highlighted the influence of remaining root dentin volume on the radicular bending resistance, stress distribution pattern, and subsequent propensity to VRF.

Effect of dentin powder on the antimicrobial properties of hyperpure chlorine-dioxide and its comparison to conventional endodontic disinfecting agents.

PubMed

Herczegh, Anna; Gyurkovics, Milán; Ghidan, Ágoston; Megyesi, Marianna; Lohinai, Zsolt

2014-06-01

Previously we found that the high purity chlorine-dioxide(ClO2) has a very potent disinfectant efficacy on oral pathogenic microorganisms and as a root canal irrigant it is able to eliminate the experimental Enterococcus faecalis(E. faecalis) infection from the root canal system. This study examines whether the presence of dentin powder influences the antibacterial efficacy of ClO 2. In an in vitro dentin powder model the following irrigants were tested against planktonic E. faecalis: 2% chlorhexidine (CHX), 2.5% sodium hypochlorite (NaOCl), 0.12%ClO2 (Solumium) and one local root canal medicament: saturated Ca(OH)2. Survival of bacteria exposed to agents without and with human dentin powder or preincubated with dentin powder was investigated. The effect of the dentin powder on ClO2 concentration was investigated by titrations. Without dentin powder ClO 2 killed all E. faecalis and delivered the best result already after 1 minute; however, after longer contact time with dentin the difference between the disinfectants disappeared. The presence of dentin powder decreased the concentration of ClO 2 and attenuated the antibacterial efficiency of ClO2 and Ca(OH)2, but did not decrease of CHX and NaOCl.Preincubation with dentin powder caused significant loss of antibacterial activity of all investigated agents, ClO2 and Ca(OH)2 having the highest reduction. As the presence of dentin powder had a negative effect on the efficacy of disinfectants, the importance of elimination of dentin scrapings and smear layer from the root canal system during endodontic treatments is highly recommended. ClO 2 can be effective for a final rinse.

"Dentinal microcracks after root canal preparation" a comparative evaluation with hand, rotary and reciprocating instrumentation.

PubMed

Priya, N Tulasi; Chandrasekhar, Veeramachaneni; Anita, S; Tummala, Muralidhar; Raj, T B Phanindhar; Badami, Vijetha; Kumar, Pradeep; Soujanya, E

2014-12-01

The purpose of this study was to compare the incidence of dentinal micro cracks after instrumentation with various types of NiTi files in rotary and reciprocating motion. One hundred human extracted mandibular central incisors were taken and divided into 10 groups (n=10 teeth per group). Group 1- No preparation, Group 2 - Hand instrumentation, Groups 3,4 - ProTaper files in rotary and reciprocating motion, Groups 5,6 - ProTaper Next files in rotary and reciprocating motion, Groups 7,8 - Oneshape files in rotary and reciprocating motion, Groups 9,10 - Reciproc files in rotary and reciprocating motion. Specimens were sectioned horizontally at 3,6 and 9 mm from the apex and dentinal micro cracks were observed under a stereomicroscope. There was a statistically significant difference between the groups (p<0.05). There were no significant differences in crack formation between the groups (Protaper Next - Rot, Protaper Next - Rec, Reciproc - Rec); (ProTaper - Rot, ProTaper - Rec, Oneshape - Rot), (Oneshape - Rot, Reciproc - Rot), (One shape Reciproc, Reciproc - Rec); (p >.05). Least cracks were seen in canals instrumented with Pro Taper Next files both in rotary and reciprocating motion. Full sequence rotary systems showed less cracks than single file systems and full sequence rotary systems showed less cracks in reciprocating motion than in rotary motion.

Association of Salivary Microbiota with Dental Caries Incidence with Dentine Involvement after 4 Years.

PubMed

Kim, Bong-Soo; Han, Dong-Hun; Lee, Ho; Oh, Bumjo

2018-03-28

Salivary microbiota alterations can correlate with dental caries development in children, and mechanisms mediating this association need to be studied in further detail. Our study explored salivary microbiota shifts in children and their association with the incidence of dental caries with dentine involvement. Salivary samples were collected from children with caries and their subsequently matched caries-free controls before and after caries development. The microbiota was analyzed by 16S rRNA gene-based high-throughput sequencing. The salivary microbiota was more diverse in caries-free subjects than in those with dental caries with dentine involvement (DC). Although both groups exhibited similar shifts in microbiota composition, an association with caries was found by function prediction. Analysis of potential microbiome functions revealed that Granulicatella, Streptococcus, Bulleidia , and Staphylococcus in the DC group could be associated with the bacterial invasion of epithelial cells, phosphotransferase system, and D -alanine metabolism, whereas Neisseria, Lautropia , and Leptotrichia in caries-free subjects could be associated with bacterial motility protein genes, linoleic acid metabolism, and flavonoid biosynthesis, suggesting that functional differences in the salivary microbiota may be associated with caries formation. These results expand the current understanding of the functional significance of the salivary microbiome in caries development, and may facilitate the identification of novel biomarkers and treatment targets.

Resin–dentin bonds to EDTA-treated vs. acid-etched dentin using ethanol wet-bonding

PubMed Central

Sauro, Salvatore; Toledano, Manuel; Aguilera, Fatima Sánchez; Mannocci, Francesco; Pashley, David H.; Tay, Franklin R.; Watson, Timothy F.; Osorio, Raquel

2013-01-01

Objective To compare resin–dentin bond strengths and the micropermeability of hydrophobic vs. hydrophilic resins bonded to acid-etched or EDTA-treated dentin, using the ethanol wet-bonding technique. Methods Flat dentin surfaces from extracted human third molars were conditioned before bonding with: 37% H3PO4 (15 s) or 0.1 M EDTA (60 s). Five experimental resin blends of different hydrophilicities and one commercial adhesive (SBMP: Scotchbond Multi-Purpose) were applied to ethanol wet-dentin (1 min) and light-cured (20 s). The solvated resins were used as primers (50% ethanol/50% comonomers) and their respective neat resins were used as the adhesive. The resin-bonded teeth were stored in distilled water (24 h) and sectioned in beams for microtensile bond strength testing. Modes of failure were examined by stereoscopic light microscopy and SEM. Confocal tandem scanning microscopy (TSM) interfacial characterization and micropermeability were also performed after filling the pulp chamber with 1 wt% aqueous rhodamine-B. Results The most hydrophobic resin 1 gave the lowest bond strength values to acid-etched dentin and all beams failed prematurely when the resin was applied to EDTA-treated dentin. Resins 2 and 3 gave intermediate bond strengths to both conditioned substrates. Resin 4, an acidic hydrophilic resin, gave the highest bond strengths to both EDTA-treated and acid-etched dentin. Resin 5 was the only hydrophilic resin showing poor resin infiltration when applied on acid-etched dentin. Significance The ethanol wet-bonding technique may improve the infiltration of most of the adhesives used in this study into dentin, especially when applied to EDTA-treated dentin. The chemical composition of the resin blends was a determining factor influencing the ability of adhesives to bond to EDTA-treated or 37% H3PO4 acid-etched dentin, when using the ethanol wet-bonding technique in a clinically relevant time period. PMID:20074787

Long-term dentin remineralization by poly(amido amine) and rechargeable calcium phosphate nanocomposite after fluid challenges.

PubMed

Liang, Kunneng; Xiao, Shimeng; Wu, Junling; Li, Jiyao; Weir, Michael D; Cheng, Lei; Reynolds, Mark A; Zhou, Xuedong; Xu, Hockin H K

2018-04-01

Previous studies investigated short-term dentin remineralization; studies on long-term dentin remineralization after fluid challenges mimicking fluids in oral environment are lacking. The objective of this study was to develop a long-term remineralization method to via poly(amido amine) (PAMAM) and rechargeable composite containing nanoparticles of amorphous calcium phosphate (NACP) after fluid challenges for the first time. NACP composite was immersed at pH 4 to exhaust its calcium (Ca) and phosphate (P) ions, and then recharged with Ca and P ions, to test the remineralization of the exhausted and recharged NACP composite. Dentin was acid-etched with 37% phosphoric acid. Four groups were prepared: (1) dentin control, (2) dentin with PAMAM, (3) dentin with the recharged NACP composite, and (4) dentin with PAMAM plus recharged NACP composite. PAMAM-coated dentin was immersed in phosphate-buffered saline with shaking for 72 days, because there is fluid flow in the mouth which could potentially detach the PAMAM from dentin. Specimens were treated with a cyclic artificial saliva/lactic acid regimen for 35 days. After 72days of immersion plus shaking, the PAMAM still successfully fulfilled its mineralization nucleation. The recharged NACP composite still provided acid-neutralization and ion re-release, which did not decrease with increasing the number of recharge cycles. The immersed-PAMAM plus NACP achieved complete dentin remineralization and restored the hardness to that of healthy dentin. In conclusion, superior long-term remineralization of the PAMAM plus NACP method was demonstrated for the first time. The immersed-PAMAM plus recharged NACP completely remineralized the pre-demineralized dentin, even after prolonged fluid-challenge similar to that in oral environment. The novel PAMAM plus NACP composite method is promising to provide long-term tooth protection and caries inhibition. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Qualitative Time-of-Flight Secondary Ion Mass Spectrometry Analysis of Root Dentin Irrigated with Sodium Hypochlorite, EDTA, or Chlorhexidine.

PubMed

Kolosowski, Kamil P; Sodhi, Rana N S; Kishen, Anil; Basrani, Bettina R

2015-10-01

Sodium hypochlorite (NaOCl), chelating agents, and chlorhexidine (CHX), which are commonly used irrigants during endodontic treatment, have the potential to alter the physical and chemical properties of the dentin structure. The aim of this study was to use time-of-flight secondary ion mass spectrometry to qualitatively evaluate the chemical characteristics of dentin surface and compare it with dentin exposed to NaOCl, EDTA, or CHX. Four blocks of dentin from a root of a human maxillary molar were embedded in resin and trimmed with a microtome to expose the dentin. Samples were randomly assigned to 4 treatment groups: (1) no irrigation treatment (sample A), (2) 2.5% NaOCl (sample B), (3) 17% EDTA (sample C), and (4) 2% CHX (sample D). Dentin surfaces were analyzed by time-of-flight secondary ion mass spectrometry, which allowed characterization of dentin surface chemistry by both imaging and mass spectroscopic analysis obtained in high mass and spatial resolution modes. Sample A revealed intense peaks characteristics of hydroxyapatite in addition to Na(+), K(+), CH4N(+), CN(-), CNO(-), Mg(+), F(-), and HCO2(-) peaks. Sample B showed severely decreased CH4N(+) and increased intensity of Cl(-). Sample C lacked Ca(+) and Mg(+) and showed decreased PO2(-) and PO3(-). Sample D exhibited a distinct presence of CHX. The spectral image of sample A displayed even distribution of Na(+) and Ca(+) on a smeared surface. The surfaces of samples B and D had patent dentinal tubules, whereas sample D showed an intense CHX signal. Sample C had some patent dentinal tubules and lacked Ca(+). NaOCl removed protein components from the dentin matrix, EDTA removed calcium and magnesium ions from the dentin, and CHX formed an adsorbed layer on the dentin surface. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Dental Pulp and Dentin Tissue Engineering and Regeneration – Advancement and Challenge

PubMed Central

Huang, George T.-J.

2012-01-01

Hard tissue is difficult to repair especially dental structures. Tooth enamel is incapable of self-repairing whereas dentin and cememtum can regenerate with limited capacity. Enamel and dentin are commonly under the attack by caries. Extensive forms of caries destroy enamel and dentin and can lead to dental pulp infection. Entire pulp amputation followed by the pulp space disinfection and filled with an artificial rubber-like material is employed to treat the infection --commonly known as root canal or endodontic therapy. Regeneration of dentin relies on having vital pulps; however, regeneration of pulp tissue has been difficult as the tissue is encased in dentin without collateral blood supply except from the root apical end. With the advent of modern tissue engineering concept and the discovery of dental stem cells, regeneration of pulp and dentin has been tested. This article will review the recent endeavor on pulp and dentin tissue engineering and regeneration. The prospective outcome of the current advancement and challenge in this line of research will be discussed. PMID:21196351

Changes in deciduous and permanent dentinal tubules diameter after several conditioning protocols: In vitro study.

PubMed

de Los Angeles Moyaho-Bernal, María; Contreras-Bulnes, Rosalía; Rodríguez-Vilchis, Laura Emma; Rubio-Rosas, Efraín

2018-05-08

Innovators conditioning protocols are emerged in permanent dentin, however for deciduous dentin the information is limited; the aim of this study was to evaluate in vitro diameter of deciduous and permanent dentinal tubules after several conditioning protocols. Eighty dentin samples were distributed in sixteen groups (n = 5 p/g) and dentin surface was conditioned as follow: G1D/G1P acid etching; G2D/G2P, self-etch adhesive; G3D/G3P, G4D/G4P, Er: YAG laser irradiation at 200 mJ-25.5 J/cm 2 and 300 mJ-38.2 J/cm 2 , at 10 Hz under water spray respectively; G5D/G5P, G6D/G6P, G7D/G7P, and G8D/G8P were irradiated under the same energy densities followed phosphoric acid or self-etch adhesive conditioning. The sample dentin of deciduous and permanent teeth was analyzed with scanning electron microscopy and tubule diameter was evaluated by Image Tools Scandium program. Data were subjected to one-way analysis ANOVA to compare among groups with a level of significance at p ≤ .05. For deciduous dentin, diameters were from 1.52 ± 0.32 µm in G3D to 3.88 ± 0.37 µm in G1D; narrowest and widest diameter, respectively (p < .000). While permanent dentin tubules exhibited diameters from 1.16 ± 0.16/1.19 ± 0.12 µm in G7P/G8P to 2.76 ± 0.28 µm in G6P; narrowest and widest diameter, respectively (p < .000). All dentin conditioning protocols produced more open dentin tubules (diameter size) in deciduous dentin than permanent, specific conditioning protocols are required for each tissue (deciduous or permanent dentin), since same protocol produced stronger effects on primary dentin, which is important for dental clinical success in children and adolescents. © 2018 Wiley Periodicals, Inc.

Effect of chlorhexidine disinfectant on bond strength of glass ionomer cement to dentin using atraumatic restorative treatment.

PubMed

Wadenya, Rose; Menon, Sandhya; Mante, Francis

2011-01-01

This study investigated the effect of 2% chlorhexidine gluconate (CHX) disinfectant on bond strength (BS) of high-density glass ionomer cement (HDGIC) to dentin following atraumatic restorative treatment (ART) and conventional preparations. Specimens were divided into four groups: Group 1--ART (control); Group 2--ART with CHX disinfection; Group 3--Conventional (control); Group 4--Conventional with CHX disinfection. HDGIC was packed in cylindrical molds placed over flat dentin surfaces; BS was measured after seven days. ART-prepared dentin surfaces disinfected with CHX provided bonding to HDGIC that was comparable to untreated dentin and to conventionally prepared dentin.

Analysis of the Color and Fluorescence Alterations of Enamel and Dentin Treated With Hydrogen Peroxide.

PubMed

Caneppele, Taciana Marco Ferraz; Rocha Gomes Torres, Carlos; Bresciani, Eduardo

2015-10-01

The aim of this study was to evaluate the effect of hydrogen peroxide whitening on fluorescence and color of bovine enamel and dentin. Twenty five dentin discs and 25 enamel discs, with 6 mm diameter and 1 mm thick, were obtained. Direct fluorescence (spectrofluorophotometry) and color (spectrophotometry) were assessed. After fluorescence and color baseline measurements, specimens were immersed in a 35% hydrogen peroxide (HP) solution for 1 h. This procedure was repeated after 7 days. Final fluorescence and color measurements were performed after the second immersion. Chemical characterization of 5 additional specimens was also performed. Data were submitted to repeated analysis of variance and Tukey's test for fluorescence and unpaired t-test for color and chemical components (p<0.05). Fluorescence decreased significantly in dentin specimens after whitening. Enamel presented lower fluorescence than dentin at baseline, but this parameter did not decrease after whitening. Color changes were observed for both substrates, with significantly greater whitening effect in dentin (ΔE=10.37) (p<0.001). Whitening by hydrogen peroxide induced significant decrease in fluorescence of tooth dentin and promoted significant color changes in dentin and enamel with more accentuated outcomes in dentin.

Tooth dentin defects reflect genetic disorders affecting bone mineralization

PubMed Central

Vital, S. Opsahl; Gaucher, C.; Bardet, C.; Rowe, P.S.; George, A.; Linglart, A.; Chaussain, C.

2012-01-01

Several genetic disorders affecting bone mineralization may manifest during dentin mineralization. Dentin and bone are similar in several aspects, especially pertaining to the composition of the extracellular matrix (ECM) which is secreted by well-differentiated odontoblasts and osteoblasts, respectively. However, unlike bone, dentin is not remodelled and is not involved in the regulation of calcium and phosphate metabolism. In contrast to bone, teeth are accessible tissues with the shedding of deciduous teeth and the extractions of premolars and third molars for orthodontic treatment. The feasibility of obtaining dentin makes this a good model to study biomineralization in physiological and pathological conditions. In this review, we focus on two genetic diseases that disrupt both bone and dentin mineralization. Hypophosphatemic rickets is related to abnormal secretory proteins involved in the ECM organization of both bone and dentin, as well as in the calcium and phosphate metabolism. Osteogenesis imperfecta affects proteins involved in the local organization of the ECM. In addition, dentin examination permits evaluation of the effects of the systemic treatment prescribed to hypophosphatemic patients during growth. In conclusion, dentin constitutes a valuable tool for better understanding of the pathological processes affecting biomineralization. PMID:22296718

[Effect of core: dentin thickness ratio on the flexure strength of IPS Empress II heat-pressed all-ceramic restorative material].

PubMed

Liu, Yi-hong; Feng, Hai-lan; Bao, Yi-wang; Qiu, Yan

2007-02-18

To evaluate the effect of core:dentin thickness ratio on the flexure strength, fracture mode and origin of bilayered IPS Empress II ceramic composite specimens. IPS Empress II core ceramic, dentin porcelain and bilayered composite specimens with core:dentin thickness ratio of 2:1 and 1:1 were tested in three-point flexure strength. Mean strengths and standard deviations were determined. The optical microscopy was employed for identification of the fracture mode and origin. The flexure strength of dentin porcelain was the smallest(62.7 MPa), and the strength of bilayered composite specimens was smaller than single-layered core ceramic(190.2 MPa). The core: dentin ratio did not influence the strength of bilayered composite specimens. The frequency of occurrence of bilayered specimen delaminations was higher in the group of core: dentin thickness ratio of 1:1 than in the group of 2:1. IPS Empress II core ceramic was significantly stronger than veneering dentin porcelain. Core:dentin thickness ratio could significantly influence the fracture mode and origin, and bilayered IPS Empress II ceramic composite specimens showed little influence in the fracture strength.

The importance of size-exclusion characteristics of type I collagen in bonding to dentin matrices

PubMed Central

M, Takahashi; M, Nakajima; J, Tagami; DLS, Scheffel; RM, Carvalho; A, Mazzoni; M, Carrilho; A, Tezvergil-Mutluay; L, Breschi; L, Tjäderhane; SS, Jang; FR, Tay; KA, Agee; DH, Pashley

2013-01-01

The mineral phase of dentin is located primarily within collagen fibrils. During development, bone or dentin collagen fibrils are formed first and then water within the fibril is replaced with apatite crystallites. Mineralized collagen contains very little water. During dentin bonding, acid-etching of mineralized dentin solubilizes the mineral crystallites and replaces them with water. During the infiltration phase of dentin bonding, adhesive comonomers are supposed to replace all of the collagen water with adhesive monomers that are then polymerized into copolymers. The authors of a recently published review suggested that dental monomers were too large to enter and displace water from collagen fibrils. If that were true, the endogenous proteases bound to dentin collagen could be responsible for unimpeded collagen degradation that is responsible for the poor durability of resin-dentin bonds. The current work studied the size-exclusion characteristics of dentin collagen, using a gel-filtration-like column chromatography technique, using dentin powder instead of Sephadex. The elution volumes of test molecules, including adhesive monomers, revealed that adhesive monomers smaller than about 1000 Da can freely diffuse into collagen water, while molecules of 10,000 Da begin to be excluded, and bovine serum albumin (66,000 Da) was fully excluded. These results validate the concept that dental monomers can permeate between collagen molecules during infiltration by etch-and-rinse adhesives. PMID:23928333

Effect of a novel bioactive glass-ceramic on dentinal tubule occlusion: an in vitro study.

PubMed

Zhong, Y; Liu, J; Li, X; Yin, W; He, T; Hu, D; Liao, Y; Yao, X; Wang, Y

2015-03-01

This in vitro study aimed to assess the ability and efficacy of HX-BGC, a novel bioactive glass-ceramic (SiO2-P2 O5-CaO-Na2 O-SrO), to reduce dentine tubule permeability. Dentine discs from human third molars were etched and randomly allocated into five groups: Group 1--distilled water; Group 2--Sensodyne Repair toothpaste (containing NovaMin®); Group 3--HX-BGC toothpaste (containing 7.5% HX-BGC); Group 4--control toothpaste (without HX-BGC); and Group 5--HX-BGC powder. Specimens were treated daily by brushing with an electric toothbrush for 20 seconds. Between daily treatments (7 days total), specimens were immersed in artificial saliva for 24 hours. Dentine permeability was measured at baseline, after the first treatment, after the first 24-hour immersion in artificial saliva and at the end of day 7. Dentine morphology and surface deposits were observed by scanning electron microscopy after one day and 7 days of treatment, respectively. Sensodyne Repair and bioactive glass-ceramic toothpaste significantly and immediately lowered dentine permeability. The HX-BGC powder group showed the highest reduction in dentine permeability after 7 days of treatment. The novel bioactive glass-ceramic material HX-BGC is effective in reducing dentine permeability by occluding open dentine tubules, indicating that HX-BGC may be a potential treatment for dentine hypersensitivity. © 2015 Australian Dental Association.

Whole-field macro- and micro-deformation characteristic of unbound water-loss in dentin hard tissue.

PubMed

Chen, Zhenning; Nadeau, Bobby; Yu, Kevin; Shao, Xinxing; He, Xiaoyuan; Goh, M Cynthia; Kishen, Anil

2018-04-06

High-resolution deformation measurements in a functionally graded hard tissue such as human dentin are essential to understand the unbound water-loss mediated changes and their role in its mechanical integrity. Yet a whole-field, 3-dimensional (3D) measurement and characterization of fully hydrated dentin in both macro- and micro-scales remain to be a challenge. This study was conducted in 2 stages. In stage-1, a stereo-digital image correlation approach was utilized to determine the water-loss and load-induced 3D deformations of teeth in a sagittal section over consecutively acquired frames, from a fully hydrated state to nonhydrated conditions for a period up to 2 hours. The macroscale analysis revealed concentrated residual deformations at the dentin-enamel-junction and the apical regions of root in the direction perpendicular to the dentinal tubules. Significant difference in the localized deformation characteristics was observed between the inner and outer aspects of the root dentin. During quasi-static loadings, further increase in the residual deformation was observed in the dentin. In stage-2, dentin microstructural variations induced by dynamic water-loss were assessed with environmental scanning electron microscopy and atomic force microscopy (AFM), showing that the dynamic water-loss induced distention of dentinal tubules with concave tubular edges, and concurrent contraction of intertubular dentin with convex profile. The findings from the current macro- and micro-scale analysis provided insight on the free-water-loss induced regional deformations and ultrastructural changes in human dentin. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Direct Electric Field-Aided Biomimetic Mineralization System for Inducing the Remineralization of Dentin Collagen Matrix

PubMed Central

Wu, Xiao-Ting; Mei, May Lei; Li, Quan-Li; Cao, Chris Ying; Chen, Jia-Long; Xia, Rong; Zhang, Zhi-Hong; Chu, Chun Hung

2015-01-01

This in vitro study aimed to accelerate the remineralization of a completely demineralized dentine collagen block in order to regenerate the dentinal microstructure of calcified collagen fibrils by a novel electric field-aided biomimetic mineralization system in the absence of non-collagenous proteins. Completely demineralized human dentine slices were prepared using ethylene diamine tetraacetic acid (EDTA) and treated with guanidine hydrochloride to extract the bound non-collagenous proteins. The completely demineralized dentine collagen blocks were then remineralized in a calcium chloride agarose hydrogel and a sodium hydrogen phosphate and fluoride agarose hydrogel. This process was accelerated by subjecting the hydrogels to electrophoresis at 20 mA for 4 and 12 h. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were used to evaluate the resultant calcification of the dentin collagen matrix. SEM indicated that mineral particles were precipitated on the intertubular dentin collagen matrix; these densely packed crystals mimicked the structure of the original mineralized dentin. However, the dentinal tubules were not occluded by the mineral crystals. XRD and EDX both confirmed that the deposited crystals were fluorinated hydroxyapatite. TEM revealed the existence of intrafibrillar and interfibrillar mineralization of the collagen fibrils. A novel electric field-aided biomimetic mineralization system was successfully developed to remineralize a completely demineralized dentine collagen matrix in the absence of non-collagenous proteins. This study developed an accelerated biomimetic mineralization system which can be a potential protocol for the biomineralization of dentinal defects. PMID:28793685

Comparison of two different forms of varnishes in the treatment of dentine hypersensitivity: a subject-blind randomised clinical study.

PubMed

Sethna, Gulnar Dara; Prabhuji, M L V; Karthikeyan, B V

2011-01-01

Dentine hypersensitivity is one of the most frequently recorded complaints of dental discomfort. Current evidence implicates patent dentinal tubules in hypersensitive dentine, and it follows that one effective way to reduce dentine sensitivity is to occlude the dentinal tubules. The purpose of this study was to compare the efficacy of two different desensitising agents, Cervitec varnish and Gluma varnish. Two hundred fifty patients self-reporting dentine hypersensitivity completed the paired split mouth randomised, subject-blind study. Each participant had a minimum of two sensitive teeth in at least two different quadrants and displaying a response of ≥3 cm to an evaporative stimulus. The hypersensitivity levels were measured with a tactile stimulus (scratchometer), thermal stimulus (cold water test), and an evaporative stimulus (air blast test) using a visual analogue scale. The teeth were evaluated immediately after treatment, and at 4 and 12 weeks after application of the chlorhexidine-containing varnish Cervitec and the glutaraldehyde-containing varnish, Gluma Desensitizer. Statistical analysis indicated that both the desensitising varnishes were effective in alleviating dentine hypersensitivity at all time intervals compared to baseline. There was a highly statistically significantly greater reduction in dentine hypersensitivity to evaporative stimulus, cold stimulus, and tactile stimulus after application of Cervitec than after Gluma Desensitizer (P < 0.001). Both the varnishes have a therapeutic potential to alleviate dentine hypersensitivity at all time intervals compared to baseline. However, Cervitec varnish is more efficacious in reducing dentine hypersensitivity than Gluma varnish at both 4 weeks and 12 weeks post-treatment.

Influence of ethanol on dentin roughness, surface free energy, and interaction between AH Plus and root dentin.

PubMed

Pantoja, Carlos Augusto de Morais Souto; Silva, Diogo Henrique da; Soares, Adriana de Jesus; Ferraz, Caio Cezar Randi; Gomes, Brenda Paula Figueiredo de Almeida; Zaia, Alexandre Augusto; Almeida, José Flávio Affonso de

2018-01-01

This study aimed to evaluate the influence of different ethanol concentrations on dentin roughness, surface free energy, and contact angle between AH Plus and the root canal dentin. One hundred human maxillary anterior teeth were split longitudinally and 200 dentin specimens were polished to make the surface flatter and smoother. An acrylic bar was positioned between two dentin specimens and impression material was added to create a block, simulating an instrumented root canal space. Specimens were removed from the mold and cleaned in an ultrasonic bath for 10 min. Thereafter, dentin specimens were divided into four groups (n = 50) according to the drying methods used: a) wet: vacuum only, b) paper points: vacuum + absorbent paper points, c) 70% alcohol: 70% alcohol (1 min) + vacuum + absorbent paper points, and d) 100% alcohol: 100% alcohol (1 min) + vacuum + absorbent paper points. A rugosimeter and a goniometer were used to verify the roughness (Ra) and to measure the surface free energy and the contact angle between the AH Plus sealer and the root canal dentin. ANOVA and Tukey tests (α = 0.05) were used for statistical analysis. The 70% and 100% ethanol groups showed significantly decreased roughness as well as increased surface free energy in the root canal dentin when compared to the wet and paper point groups. In addition, ethanol significantly reduced the contact angle between the AH Plus sealer and the root canal dentin. Ethanol solutions (70% and 100%) provide better wettability of AH Plus sealer on dentin surfaces.

A MODEL SYSTEM TO STUDY ANTIMICROBIAL STRATEGIES IN ENDODONTIC BIOFILMS

PubMed Central

Estrela, Carlos; Sydney, Gilson Blitzkow; Figueiredo, José Antonio Poli; Estrela, Cyntia Rodrigues de Araújo

2009-01-01

The purpose of this work was to develop a model system to study antimicrobial strategies in endodontic biofilms. Enterococcus faecalis suspension was colonized in 10 human root canals. Five milliliters of Brain Heart Infusion (BHI) were mixed with 5 mL of the bacterial inoculums (E. faecalis) and inoculated with sufficient volume to fill the root canal during 60 days. This procedure was repeated every 72 h, always using 24-h pure culture prepared and adjusted to No. 1 MacFarland turbidity standard. Biofilm formation was analyzed by scanning electron microscopy (SEM). E. faecalis consistently adhered to collagen structure, colonized dentin surface, progressed towards the dentinal tubules and formed a biofilm. The proposed biofilm model seems to be viable for studies on antimicrobial strategies, and allows for a satisfactory colonization time of selected bacterial species with virulence and adherence properties. PMID:19274391

Distinct compartmentalization of dentin matrix protein 1 fragments in mineralized tissues and cells.

PubMed

Maciejewska, Izabela; Qin, Disheng; Huang, Bingzhen; Sun, Yao; Mues, Gabrielle; Svoboda, Kathy; Bonewald, Lynda; Butler, William T; Feng, Jerry Q; Qin, Chunlin

2009-01-01

Dentin matrix protein 1 (DMP1) has been shown to be critical for the formation of dentin and bone. However, the precise pathway by which DMP1 participates in dentinogenesis and osteogenesis remains to be clarified. DMP1 is present in the extracellular matrix of dentin and bone as processed NH(2)- and COOH-terminal fragments. The NH(2)-terminal fragment occurs as a proteoglycan, whereas the COOH-terminal fragment is highly phosphorylated. The differences in biochemical properties suggest that these fragments may have different tissue and cell distribution in association with distinct functions. In this study, we analyzed the distribution of the NH(2)- and COOH-terminal fragments of DMP1 in tooth, bone, osteocytes as well as MC3T3-E1 and HEK-293 cells. Immunohistochemical analyses were performed using antibodies specific to the NH(2)- or COOH-terminal region of DMP1. Clear differences in the distribution of these fragments were observed. In the teeth and bone, the NH(2)-terminal fragment was primarily located in the nonmineralized predentin and cartilage of the growth plate, while the COOH-terminal fragment accumulated in the mineralized zones. In osteocytes, the NH(2)-terminal fragment appeared more abundant along cell membrane and processes of osteocytes, while the COOH-terminal fragment was often found in the nuclei. This pattern of distribution in cellular compartments was further confirmed by analyses on MC3T3-E1 and HEK-293 cells transfected with a construct containing DMP1 cDNA. In these cell lines, the COOH-terminal fragment accumulated in cell nuclei, while the NH(2)-terminal fragment was in the cytosol. The different distribution of DMP1 fragments indicates that these DMP1 variants must perform distinct functions. Copyright 2008 S. Karger AG, Basel.

[The effect of root canal re-wetting on push-out bond strength and durability of fiber post].

PubMed

Yao, Ke; Song, Jie-wen; Li, Yan

2011-02-01

To analyze the push-out bond strength of fiber post and the durability of interface between dentin and composite resin during over drying and re-wetting of root canal. Thirty-six extracted human maxillary central incisors were randomly divided into three groups: Group A for the process of over drying, Group B for re-wetting, Group C for control. All teeth were sliced into several thin discs with thickness of 1.0 mm for micro push-out test and scanning electron microscope(SEM) observation. Push-out shear strengths of fiber post immediately after bonding in group A, B and C were (5.97 ± 1.97), (7.67 ± 2.19) and (8.46 ± 2.35) MPa. Push-out strengths of fiber post two months after water storage were (2.08 ± 1.67), (2.99 ± 1.48) and (3.22 ± 1.43) MPa. There was significantly difference in push-out strength between Group A and Group B (P < 0.05). Significantly difference in push-out strength was also found between Group A and Group C. In the condition of immediate testing, there was also significantly difference between push-out strength of cervical slice and middle slice, and between cervical slice and apical slice (P < 0.05). The water storage time has significant effect on the push-out bond strength of fiber posts (P < 0.05). Inappropriate condensation air blowing operation can cause extracted teeth root canal dentin over dry. Dehydration can destroy the formation of general structure of interface between composite resin and dentin. The over dry dentin can be turned back to wetting stage by water pouring, which can help fiber-reinforced composite post regain its normal retention strength and original adhesive durability.

Combination of Mineral Trioxide Aggregate and Platelet-rich Fibrin Promotes the Odontoblastic Differentiation and Mineralization of Human Dental Pulp Cells via BMP/Smad Signaling Pathway.

PubMed

Woo, Su-Mi; Kim, Won-Jae; Lim, Hae-Soon; Choi, Nam-Ki; Kim, Sun-Hun; Kim, Seon-Mi; Jung, Ji-Yeon

2016-01-01

Recent reports have shown that the combined use of platelet-rich fibrin (PRF), an autologous fibrin matrix, and mineral trioxide aggregate (MTA) as root filling material is beneficial for the endodontic management of an open apex. However, the potential of the combination of MTA and PRF as an odontogenic inducer in human dental pulp cells (HDPCs) in vitro has not yet been studied. The purpose of this study was to evaluate the effect of the combination of MTA and PRF on odontoblastic maturation in HDPCs. HDPCs extracted from third molars were directly cultured with MTA and PRF extract (PRFe). Odontoblastic differentiation of HDPCs was evaluated by measuring the alkaline phosphatase (ALP) activity, and the expression of odontogenesis-related genes was detected using reverse-transcription polymerase chain reaction or Western blot. Mineralization formation was assessed by alizarin red staining. HDPCs treated with MTA and PRFe significantly up-regulated the expression of dentin sialoprotein and dentin matrix protein-1 and enhanced ALP activity and mineralization compared with those with MTA or PRFe treatment alone. In addition, the combination of MTA and PRFe induced the activation of bone morphogenic proteins (BMP)/Smad, whereas LDN193189, the bone morphogenic protein inhibitor, attenuated dentin sialophosphoprotein and dentin matrix protein-1 expression, ALP activity, and mineralization enhanced by MTA and PRFe treatment. This study shows that the combination of MTA and PRF has a synergistic effect on the stimulation of odontoblastic differentiation of HDPCs via the modulation of the BMP/Smad signaling pathway. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Vertical Root Fracture initiation in curved roots after root canal preparation: A dentinal micro-crack analysis with LED transillumination

PubMed Central

Martín-Biedma, Benjamín; Varela-Patiño, Purificación; Ruíz-Piñón, Manuel; Castelo-Baz, Pablo

2017-01-01

Background One of the causative factors of root defects is the increased friction produced by rotary instrumentation. A high canal curvature may increase stress, making the tooth more susceptible to dentinal cracks. The purpose of this study was to evaluate dentinal micro-crack formation with the ProTaper NEXT and ProTaper Universal systems using LED transillumination, and to analyze the micro-crack generated at the point of maximum canal curvature. Material and Methods 60 human mandibular premolars with curvatures between 30–49° and radii between 2–4 mm were used. The root canals were instrumented using the Protaper Universal® and Protaper NEXT® systems, with the aid of the Proglider® system. The obtained samples were sectioned transversely before subsequent analysis with LED transillumination at 2 mm and 8 mm from the apex and at the point of maximum canal curvature. Defects were scored: 0 for no defects; and 1 for micro-cracks. Results Root defects were not observed in the control group. The ProTaper NEXT system caused fewer defects (16.7%) than the ProTaper Universal system (40%) (P<0.05). The ProTaper Universal system caused significantly more micro-cracks at the point of maximum canal curvature than the ProTaper NEXT system (P<0.05). Conclusions Rotary instrumentation systems often generate root defects, but the ProTaper NEXT system generated fewer dentinal defects than the ProTaper Universal system. A higher prevalence of defects was found at the point of maximum curvature in the ProTaper Universal group. Key words:Curved root, Micro-crack, point of maximum canal curvature, ProTaper NEXT, ProTaper Universal, Vertical root fracture. PMID:29167712

Antimicrobial Effects of Novel Triple Antibiotic Paste-Mimic Scaffolds on Actinomyces naeslundii Biofilm.

PubMed

Albuquerque, Maria T P; Ryan, Stuart J; Münchow, Eliseu A; Kamocka, Maria M; Gregory, Richard L; Valera, Marcia C; Bottino, Marco C

2015-08-01

Actinomyces naeslundii has been recovered from traumatized permanent teeth diagnosed with necrotic pulps. In this work, a triple antibiotic paste (TAP)-mimic scaffold is proposed as a drug-delivery strategy to eliminate A. naeslundii dentin biofilm. Metronidazole, ciprofloxacin, and minocycline were added to a polydioxanone (PDS) polymer solution and spun into fibrous scaffolds. Fiber morphology, mechanical properties, and drug release were investigated by using scanning electron microscopy, microtensile testing, and high-performance liquid chromatography, respectively. Human dentin specimens (4 × 4 × 1 mm(3), n = 4/group) were inoculated with A. naeslundii (ATCC 43146) for 7 days for biofilm formation. The infected dentin specimens were exposed to TAP-mimic scaffolds, TAP solution (positive control), and pure PDS (drug-free scaffold). Dentin infected (7-day biofilm) specimens were used for comparison (negative control). Confocal laser scanning microscopy was done to determine bacterial viability. Scaffolds displayed a submicron mean fiber diameter (PDS = 689 ± 312 nm and TAP-mimic = 718 ± 125 nm). Overall, TAP-mimic scaffolds showed significantly (P ≤ .040) lower mechanical properties than PDS. Within the first 24 hours, a burst release for all drugs was seen. A sustained maintenance of metronidazole and ciprofloxacin was observed over 4 weeks, but not for minocycline. Confocal laser scanning microscopy demonstrated complete elimination of all viable bacteria exposed to the TAP solution. Meanwhile, TAP-mimic scaffolds led to a significant (P < .05) reduction in the percentage of viable bacteria compared with the negative control and PDS. Our findings suggest that TAP-mimic scaffolds hold significant potential in the eradication/elimination of bacterial biofilm, a critical step in regenerative endodontics. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Phototherapy up-regulates dentin matrix proteins expression and synthesis by stem cells from human-exfoliated deciduous teeth.

PubMed

Turrioni, Ana Paula S; Basso, Fernanda G; Montoro, Liege A; Almeida, Leopoldina de Fátima D de; Costa, Carlos A de Souza; Hebling, Josimeri

2014-10-01

The aim of this study was to evaluate the effects of infrared LED (850nm) irradiation on dentin matrix proteins expression and synthesis by cultured stem cells from human exfoliated deciduous teeth (SHED). Near-exfoliation primary teeth were extracted (n=3), and SHED cultures were characterized by immunofluorescence using STRO-1, CD44, CD146, Nanog and OCT3/4 antibodies, before experimental protocol. The SHEDs were seeded (3×10(4) cells/cm(2)) with DMEM containing 10% FBS. After 24-h incubation, the culture medium was replaced by osteogenic differentiation medium, and the cells were irradiated with LED light at energy densities (EDs) of 0 (control), 2, or 4J/cm(2) (n=8). The irradiated SHEDs were then evaluated for alkaline phosphatase (ALP) activity, total protein (TP) production, and collagen synthesis (SIRCOL™ Assay), as well as ALP, collagen type I (Col I), dentin sialophosphoprotein (DSPP), and dentin matrix acidic phosphoprotein (DMP-1) gene expression (qPCR). Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (α=0.05). Increased ALP activity and collagen synthesis, as well as gene expression of DSPP and ALP, were observed for both EDs compared with non-irradiated cells. The ED of 4J/cm(2) also increased gene expression of COL I and DMP-1. In conclusion, infrared LED irradiation was capable of biostimulating SHEDs by increasing the expression and synthesis of proteins related with mineralized tissue formation, with overall better results for the energy dose of 4J/cm(2). Phototherapy is an additional approach for the clinical application of LED in Restorative Dentistry. Infrared LED irradiation of the cavity's floor could biostimulate subjacent pulp cells, improving local tissue healing. Copyright © 2014 Elsevier Ltd. All rights reserved.

Cyclic mechanical loading promotes bacterial penetration along composite restoration marginal gaps

PubMed Central

Khvostenko, D.; Salehi, S.; Naleway, S. E.; Hilton, T. J.; Ferracane, J. L.; Mitchell, J. C.; Kruzic, J. J.

2015-01-01

Objectives Secondary caries is the most common reason for composite restoration replacement and usually forms between dentin and the filling. The objective of this study was to investigate the combined effect of cyclic loading and bacterial exposure on bacterial penetration into gaps at the interface between dentin and resin composite restorative material using a novel bioreactor system and test specimen design. Methods Human molars were machined into 3 mm thick disks with 2 mm deep × 5 mm diameter cavity preparations into which composite restorations were placed. A ∼15-30 micrometer (small) or ∼300 micrometer wide (large) dentin-restoration gap was introduced along half of the interface between the dentin and restoration. Streptococcus mutans UA 159 biofilms were grown on each sample prior to testing in a bioreactor both with and without cyclic loading. Both groups of samples were tested for 2 weeks and post-test biofilm viability was confirmed with a live-dead assay. Samples were fixed, mounted and cross-sectioned to reveal the gaps and observe the depth of bacterial penetration. Results It was shown that for large gap samples the bacteria easily penetrated to the full depth of the gap independent of loading or non-loading conditions. The results for all cyclically loaded small gap samples show a consistently deep bacterial penetration down 100% of the gap while the average penetration depth was only 67% for the non-loaded samples with only two of six samples reaching 100%. Significance A new bioreactor was developed that allows combining cyclic mechanical loading and bacterial exposure of restored teeth for bacterial biofilm and demineralization studies. Cyclic loading was shown to aid bacterial penetration into narrow marginal gaps, which could ultimately promote secondary caries formation. PMID:25900624

A Novel Combinatorial Therapy With Pulp Stem Cells and Granulocyte Colony-Stimulating Factor for Total Pulp Regeneration

PubMed Central

Iohara, Koichiro; Murakami, Masashi; Takeuchi, Norio; Osako, Yohei; Ito, Masataka; Ishizaka, Ryo; Utunomiya, Shinji; Nakamura, Hiroshi; Matsushita, Kenji

2013-01-01

Treatment of deep caries with pulpitis is a major challenge in dentistry. Stem cell therapy represents a potential strategy to regenerate the dentin-pulp complex, enabling conservation and restoration of teeth. The objective of this study was to assess the efficacy and safety of pulp stem cell transplantation as a prelude for the impending clinical trials. Clinical-grade pulp stem cells were isolated and expanded according to good manufacturing practice conditions. The absence of contamination, abnormalities/aberrations in karyotype, and tumor formation after transplantation in an immunodeficient mouse ensured excellent quality control. After autologous transplantation of pulp stem cells with granulocyte-colony stimulating factor (G-CSF) in a dog pulpectomized tooth, regenerated pulp tissue including vasculature and innervation completely filled in the root canal, and regenerated dentin was formed in the coronal part and prevented microleakage up to day 180. Transplantation of pulp stem cells with G-CSF yielded a significantly larger amount of regenerated dentin-pulp complex compared with transplantation of G-CSF or stem cells alone. Also noteworthy was the reduction in the number of inflammatory cells and apoptotic cells and the significant increase in neurite outgrowth compared with results without G-CSF. The transplanted stem cells expressed angiogenic/neurotrophic factors. It is significant that G-CSF together with conditioned medium of pulp stem cells stimulated cell migration and neurite outgrowth, prevented cell death, and promoted immunosuppression in vitro. Furthermore, there was no evidence of toxicity or adverse events. In conclusion, the combinatorial trophic effects of pulp stem cells and G-CSF are of immediate utility for pulp/dentin regeneration, demonstrating the prerequisites of safety and efficacy critical for clinical applications. PMID:23761108

[Mantle dentin as biomodel of materials for structural teeth restoration].

PubMed

Starodubova, A V; Vinnichenko, Yu A; Pourovskaya, I Ya; Rusanov, F S

The article describes a structural element of natural teeth - mantle dentin. It has been shown that the presence of this element in the structure of a natural tooth largely ensures its strength under the influence of repeated loads in a functional oral environment and arrests crack growth at the enamel/dentine interface. This later effect is explained by the influence of a thin layer of mantle dentine, which has physical and mechanical characteristics different from that of the main dentin.

Free energy landscape of a minimalist salt bridge model.

PubMed

Li, Xubin; Lv, Chao; Corbett, Karen M; Zheng, Lianqing; Wu, Dongsheng; Yang, Wei

2016-01-01

Salt bridges are essential to protein stability and dynamics. Despite the importance, there has been scarce of detailed discussion on how salt bridge partners interact with each other in distinct solvent exposed environments. In this study, employing a recent generalized orthogonal space tempering (gOST) method, we enabled efficient molecular dynamics simulation of repetitive breaking and reforming of salt bridge structures within a minimalist salt-bridge model, the Asp-Arg dipeptide and thereby were able to map its detailed free energy landscape in aqueous solution. Free energy surface analysis shows that although individually-solvated states are more favorable, salt-bridge states still occupy a noticeable portion of the overall population. Notably, the competing forces, e.g. intercharge attractions that drive the formation of salt bridges and solvation forces that pull the charged groups away from each other, are energetically comparable. As the result, the salt bridge stability is highly tunable by local environments; for instance when local water molecules are perturbed to interact more strongly with each other, the population of the salt-bridge states is likely to increase. Our results reveal the critical role of local solvent structures in modulating salt-bridge partner interactions and imply the importance of water fluctuations on conformational dynamics that involves solvent accessible salt bridge formations. © 2015 The Protein Society.

Incidence of apical crack formation and propagation during removal of root canal filling materials with different engine driven nickel-titanium instruments.

PubMed

Özyürek, Taha; Tek, Vildan; Yılmaz, Koray; Uslu, Gülşah

2017-11-01

To determine the incidence of crack formation and propagation in apical root dentin after retreatment procedures performed using ProTaper Universal Retreatment (PTR), Mtwo-R, ProTaper Next (PTN), and Twisted File Adaptive (TFA) systems. The study consisted of 120 extracted mandibular premolars. One millimeter from the apex of each tooth was ground perpendicular to the long axis of the tooth, and the apical surface was polished. Twenty teeth served as the negative control group. One hundred teeth were prepared, obturated, and then divided into 5 retreatment groups. The retreatment procedures were performed using the following files: PTR, Mtwo-R, PTN, TFA, and hand files. After filling material removal, apical enlargement was done using apical size 0.50 mm ProTaper Universal (PTU), Mtwo, PTN, TFA, and hand files. Digital images of the apical root surfaces were recorded before preparation, after preparation, after obturation, after filling removal, and after apical enlargement using a stereomicroscope. The images were then inspected for the presence of new apical cracks and crack propagation. Data were analyzed with χ 2 tests using SPSS 21.0 software. New cracks and crack propagation occurred in all the experimental groups during the retreatment process. Nickel-titanium rotary file systems caused significantly more apical crack formation and propagation than the hand files. The PTU system caused significantly more apical cracks than the other groups after the apical enlargement stage. This study showed that retreatment procedures and apical enlargement after the use of retreatment files can cause crack formation and propagation in apical dentin.

A comparison of the effects of Nd:YAG and Ho:YAG laser irradiation on dentine and enamel.

PubMed

Cernavin, I

1995-04-01

This preliminary study was undertaken to investigate the effects of Nd:YAG and Ho:YAG lasers on enamel and dentine of extracted teeth. The Ho:YAG laser (spot size 250 microns, energy density 4160 J/cm2) produced a cleaner puncture in dentine with less melting of the surrounding tissue than did the Nd:YAG laser (spot size 20 microns), energy density 50,000 J/cm2), which produced considerable melting and recrystallization of dentine and was more difficult to control. It was possible to cut enamel and dentine with both lasers, but considerable melted and recrystallized enamel was produced. From the limited observations of this study it appears that the Ho:YAG laser is more suitable for cutting both enamel and dentine than the Nd:YAG laser. More work needs to be done to ascertain the effect on enamel and dentine of modification of the parameters of both lasers.

Repair of dentin defects from DSPP knockout mice by PILP mineralization

PubMed Central

Nurrohman, H.; Saeki, K.; Carneiro, K.; Chien, Y.C.; Djomehri, S.; Ho, S.P.; Qin, C.; Marshall, S.J.; Gower, L.B.; Marshall, G.W.; Habelitz, S.

2016-01-01

Dentinogenesis imperfecta type II (DGI-II) lacks intrafibrillar mineral with severe compromise of dentin mechanical properties. A Dspp knockout (Dspp−/−) mouse, with a phenotype similar to that of human DGI-II, was used to determine if poly-L-aspartic acid [poly(ASP)] in the “polymer-induced liquid-precursor” (PILP) system can restore its mechanical properties. Dentin from six-week old Dspp−/− and wild-type mice was treated with CaP solution containing poly(ASP) for up to 14 days. Elastic modulus and hardness before and after treatment were correlated with mineralization from Micro x-ray computed tomography (Micro-XCT). Transmission electron microscopy (TEM)/Selected area electron diffraction (SAED) were used to compare matrix mineralization and crystallography. Mechanical properties of the Dspp−/− dentin were significantly less than wild-type dentin and recovered significantly (P < 0.05) after PILP-treatment, reaching values comparable to wild-type dentin. Micro-XCT showed mineral recovery similar to wild-type dentin after PILP-treatment. TEM/SAED showed repair of patchy mineralization and complete mineralization of defective dentin. This approach may lead to new strategies for hard tissue repair. PMID:27239097

The reduction in fatigue crack growth resistance of dentin with depth.

PubMed

Ivancik, J; Neerchal, N K; Romberg, E; Arola, D

2011-08-01

The fatigue crack growth resistance of dentin was characterized as a function of depth from the dentino-enamel junction. Compact tension (CT) specimens were prepared from the crowns of third molars in the deep, middle, and peripheral dentin. The microstructure was quantified in terms of the average tubule dimensions and density. Fatigue cracks were grown in-plane with the tubules and characterized in terms of the initiation and growth responses. Deep dentin exhibited the lowest resistance to the initiation of fatigue crack growth, as indicated by the stress intensity threshold (ΔK(th) ≈ 0.8 MPa•m(0.5)) and the highest incremental fatigue crack growth rate (over 1000 times that in peripheral dentin). Cracks in deep dentin underwent incremental extension under cyclic stresses that were 40% lower than those required in peripheral dentin. The average fatigue crack growth rates increased significantly with tubule density, indicating the importance of microstructure on the potential for tooth fracture. Molars with deep restorations are more likely to suffer from the cracked-tooth syndrome, because of the lower fatigue crack growth resistance of deep dentin.

Effect of pulsed Nd:YAG on dentin morphological changes

NASA Astrophysics Data System (ADS)

Moriyama, Eduardo H.; Zangaro, Renato A.; Villaverde, Antonio G. J. B.; Watanabe-Sei, Ii; Munin, Egberto; Sasaki, Luis H.; Otsuka, Daniel K.; Lobo, Paulo D. d. C.; Pacheco, Marcos T. T.; Junior, Durval R.

2002-06-01

Infrared lasers have been used for several clinical applications in dentistry, including laser ablation, oral surgeries and dentin hypersensitivity treatment. Despite of dentin low absorption coefficient in the near infrared spectrum, Nd:YAG laser radiation ((lambda) = 1064 nm) is able to melt the human dentin surface resulting in dentin tubules closure that can suppress the symptoms of dentin hypersensitivity pathology. Objectives: This study aims to analyze, through SEM technique, the morphological changes in dentin surface after Nd:YAG laser irradiation using different parameters in energy distribution. Materials and Methods: In this study sixteen human dentin samples were submitted to Nd:YAG laser radiation using a total energy of 900mJ distributed in one, two, three or six laser pulses with energy for each pulse of 900, 450, 300 or 150 mJ respectively. All the samples were irradiated with laser pulse width of 90ms, pulse intervals of 300 ms and spot size area of 0,005 cm2. Results: SEM analysis suggests that differences in energy distribution results in morphological differences even though the same energy is used for all the samples.

Fractography and fracture toughness of human dentin.

PubMed

Yan, J; Taskonak, B; Mecholsky, J J

2009-10-01

Dentin, the mineralized tissue forming the bulk of the tooth, serves as an energy-absorbing cushion for the hard, wear-resistant enamel and protects the inner soft tissues. Several studies used fracture mechanics methods to study the fracture toughness of dentin. However, all of them utilized precracks and cannot be used to estimate the intrinsic critical flaw size of dentin. We applied quantitative fractography to study the fracture pattern and fracture toughness of human dentin. Sixteen specimens were prepared from the coronal dentin and fractured in three-point flexure. Fracture surfaces were examined using a scanning electron microscope and the fracture toughness was calculated using a fracture mechanics equation. It was found that human dentin has a fracture surface similar to those of brittle materials. Twist hackle markings were observed and were used to identify the fracture origins. Average fracture toughness of all specimens was found to be 2.3 MPa m(1/2) and the average critical flaw size was estimated to 120 mum. It is suggested that fractography is a promising technique in analyzing the fracture of dentin under catastrophic failure.

Phosphorus Effects of Mesoporous Bioactive Glass on Occlude Exposed Dentin

PubMed Central

Chen, Wen-Cheng; Chen, Cheng-Hwei; Kung, Jung-Chang; Hsiao, Yu-Cheng; Shih, Chi-Jen; Chien, Chi-Sheng

2013-01-01

In recent studies, sealing of exposed dentinal tubules is generally considered as one of the most effective strategies to treat dentin hypersensitivity. Mesoporous bioactive glass (MBG) is a potential material for treating dentin hypersensitivity due to its highly specific areas for dissolution and re-precipitated reaction for reduction in dentin permeability. The groups of commercial products of PerioGlas®, synthetic MBG and MBG without phosphorus (MBGNP) were compared. The MBG and MBGNP powders were prepared by the sol-gel method and mixed with different calculated ratios of phosphoric acid (PA) and then was brushed onto dentin surfaces. We used X-ray diffractometer (XRD), scanning electronic microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) to investigate the physiochemistry and the occlusion ability of dentinal tubules. The results showed that MBG paste mixed with PA solution has a better ability for occluding dentinal tubules than MBGNP; it has a short reaction time and good operability. The major crystallite phase of MBG agents was monocalcium phosphate monohydrate [Ca(H2PO4)2·H2O] in the early stages of the reactions. MBG pastes that were mixed with 30% and 40% PA had the ability to create excellent penetration depth greater than 80 μm. These agents have the potential to treat dentin hypersensitivity. PMID:28788393

Chlorhexidine stabilizes the adhesive interface: a 2 year in vitro study

PubMed Central

Breschi, Lorenzo; Mazzoni, Annalisa; Nato, Fernando; Carrilho, Marcela; Visintini, Erika; Tjäderhane, Leo; Ruggeri, Alessandra; Tay, Franklin R; De Stefano Dorigo, Elettra; Pashley, David H

2013-01-01

Objectives This study evaluated the role of endogenous dentin MMPs in auto-degradation of collagen fibrils within adhesive-bonded interfaces. The null hypotheses tested were that adhesive blends or chlorhexidine digluconate (CHX) application does not modify dentin MMPs activity and that CHX used as therapeutic primer does not improve the stability of adhesive interfaces over time. Methods Zymograms of protein extracts from human dentin powder incubated with Adper Scotchbond 1XT (SB1XT) on untreated or 0.2–2% CHX treated dentin were obtained to assay dentin MMPs activity. Microtensile bond strength and interfacial nanoleakage expression of SB1XT bonded interfaces (with or without CHX pre-treatment for 30s on the etched surface) were analyzed immediately and after 2 yr of storage in artificial saliva at 37°C. Results Zymograms showed that application of SB1XT to human dentin powder increases MMP-2 activity, while CHX pre-treatment inhibited all dentin gelatinolytic activity, irrespective from the tested concentration. CHX significantly lowered the loss of bond strength and nanoleakage seen in acid-etched resin-bonded dentin artificially aged for 2 yr. Significance The study demonstrates the active role of SB1XT in dentin MMP-2 activation and the efficacy of CHX inhibition of MMPs even if used at low concentration (0.2%). PMID:20045177

Bonding durability of a self-etching primer system to normal and caries-affected dentin under hydrostatic pulpal pressure in vitro.

PubMed

Nakajima, Masatoshi; Hosaka, Keiichi; Yamauti, Monica; Foxton, Richard M; Tagami, Junji

2006-06-01

To evaluate the bonding durability of a self-etching primer system to normal and caries-affected dentin under hydrostatic pulpal pressure. 18 extracted human molars with occlusal caries were used. Their occlusal dentin surfaces were ground flat to expose normal and caries-affected dentin using #600 SiC paper under running water. Clearfil SE Bond was placed on the dentin surface including the caries-affected dentin according to the manufacturer's instructions and then the crowns were built up with resin composite (Clearfil AP-X) under either a pulpal pressure of 15 cm H2O or none (control). The bonded specimens were stored in 100% humidity for 1 day (control) or for 1 week and 1 month with hydrostatic pulpal pressure. After storage, the specimens were serially sectioned into 0.7 mm-thick slabs and trimmed to an hour-glass shape with a 1 mm2 cross-section, isolated by normal or caries-affected dentin, and then subjected to the micro-tensile bond test. Data were analyzed by two-way ANOVA and Tukey's test (P< 0.05). Hydrostatic pulpal pressure significantly reduced the bond strength to normal dentin after 1-month storage (P< 0.05), but did not affect the bond strength to caries-affected dentin.

Evaluation of desensitizing agents on dentin permeability and dentinal tubule occlusion: an in vitro study.

PubMed

Oberg, Carolina; Pochapski, Marcia Thais; Farago, Paulo Vitor; Granado, Carlos Jose Fernandes; Pilatti, Gibson Luiz; Santos, Fabio Andre

2009-01-01

One hundred twelve specimens from bovine incisors were divided into eight groups: Group 1 (treated with 10% strontium chloride gel), Group 2 (treated with 2% sodium fluoride gel), Group 3 (treated with 2% stannous fluoride gel), Group 4 (treated with 5% potassium nitrate gel), Group 5 (treated with 10% potassium nitrate gel), Group 6 (treated with 3% potassium oxalate gel), Group 7 (treated with hydroxyethylcellulose gel), and Group 8 (which received no treatment). Dentinal tubules were exposed after 0.5 mm of deep abrasion using a carbide bur and EDTA gel application. After each treatment, dentin permeability, tubule occlusion, and chemical elements on dentin were analyzed. There was a significant difference among groups in dentin permeability (p < 0.05 ANOVA). Groups 4, 5, and 6 showed the lowest values, while Groups 1, 7, and 8 exhibited the highest. Groups 1, 2, 3, 7, and 8 showed open dentinal tubules, Groups 4 and 5 had partial tubule occlusion, and most of the tubules in Group 6 were obliterated. Energy-dispersive x-rays revealed similar chemical characteristics among the experimental agents used, with traces of strontium, fluoride, sodium, and potassium. Within the limits of the study, 3% potassium oxalate gel showed the best results in terms of dentin permeability and dentinal tubule occlusion.

In Vitro Ability of a Novel Nanohydroxyapatite Oral Rinse to Occlude Dentine Tubules

PubMed Central

Hill, Robert G.; Chen, Xiaohui; Gillam, David G.

2015-01-01

Objectives. The aim of the study was to investigate the ability of a novel nanohydroxyapatite (nHA) desensitizing oral rinse to occlude dentine tubules compared to selected commercially available desensitizing oral rinses. Methods. 25 caries-free extracted molars were sectioned into 1 mm thick dentine discs. The dentine discs (n = 25) were etched with 6% citric acid for 2 minutes and rinsed with distilled water, prior to a 30-second application of test and control oral rinses. Evaluation was by (1) Scanning Electron Microscopy (SEM) of the dentine surface and (2) fluid flow measurements through a dentine disc. Results. Most of the oral rinses failed to adequately cover the dentine surface apart from the nHa oral rinse. However the hydroxyapatite, 1.4% potassium oxalate, and arginine/PVM/MA copolymer oral rinses, appeared to be relatively more effective than the nHA test and negative control rinses (potassium nitrate) in relation to a reduction in fluid flow measurements. Conclusions. Although the novel nHA oral rinse demonstrated the ability to occlude the dentine tubules and reduce the fluid flow measurements, some of the other oral rinses appeared to demonstrate a statistically significant reduction in fluid flow through the dentine disc, in particular the arginine/PVM/MA copolymer oral rinse. PMID:26161093

Origins of bone repair in the armour of fossil fish: response to a deep wound by cells depositing dentine instead of dermal bone.

PubMed

Johanson, Zerina; Smith, Moya; Kearsley, Anton; Pilecki, Peter; Mark-Kurik, Elga; Howard, Charles

2013-10-23

The outer armour of fossil jawless fishes (Heterostraci) is, predominantly, a bone with a superficial ornament of dentine tubercles surrounded by pores leading to flask-shaped crypts (ampullae). However, despite the extensive bone present in these early dermal skeletons, damage was repaired almost exclusively with dentine. Consolidation of bone, by dentine invading and filling the vascular spaces, was previously recognized in Psammolepis and other heterostracans but was associated with ageing and dermal shield wear (reparative). Here, we describe wound repair by deposition of dentine directly onto a bony scaffold of fragmented bone. An extensive wound response occurred from massive deposition of dentine (reactionary), traced from tubercle pulp cavities and surrounding ampullae. These structures may provide the cells to make reparative and reactionary dentine, as in mammalian teeth today in response to stimuli (functional wear or damage). We suggest in Psammolepis, repair involved mobilization of these cells in response to a local stimulatory mechanism, for example, predator damage. By comparison, almost no new bone is detected in repair of the Psammolepis shield. Dentine infilling bone vascular tissue spaces of both abraded dentine and wounded bone suggests that recruitment of this process has been evolutionarily conserved over 380 Myr and precedes osteogenic skeletal repair.

Influence of matrix metalloproteinase synthetic inhibitors on dentin microtensile bond strength of resin cements.

PubMed

Stape, T H S; Menezes, M S; Barreto, B C F; Aguiar, F H B; Martins, L R; Quagliatto, P S

2012-01-01

This study evaluated the effect of dentin pretreatment with 2% chlorhexidine (CHX) or 24% ethylenediamine tetra-acetic acid gel (EDTA) on the dentin microtensile bond strength (μTBS) of resin cements. Composite blocks were luted to superficial noncarious human dentin (n=10) using two resin cements (RelyX ARC [ARC] and RelyX U100 [U100]) and three dentin pretreatments (without pretreatment-control, CHX, and EDTA). CHX was applied for 60 seconds on the acid-etched dentin in the ARC/CHX group, and for the same time on smear layer-covered dentin in the U100/CHX group. EDTA was applied for 45 seconds on smear-covered dentin in the U100/EDTA group, and it replaced phosphoric acid conditioning in the ARC/EDTA group for 60 seconds. After storage in water for 24 hours, specimens were prepared for microtensile bond strength testing. The results were submitted to two-way analysis of variance (ANOVA) followed by Tukey test. ARC produced significantly higher μTBS (p<0.05) compared to the U100, except when EDTA was used. For ARC, no pretreatment and CHX produced higher μTBS than EDTA. For U100, EDTA produced higher μTBS; no statistical difference occurred between CHX pretreatment and when no pretreatment was performed. While CHX did not affect immediate dentin bond strength of both cements, EDTA improved bond strength of U100, but it reduced dentin bond strength of ARC.

Mapping large extensions of flat dentin through digital microscopy: introduction to the method and possible applications.

PubMed

Reis, Claudia; De-Deus, Gustavo; Marins, Juliana; Fidel, Sandra; Fidel, Rivail; Paciornik, Sidnei

2012-08-01

To introduce a mapping method to characterize large dentin surfaces using digital microscopy and to discuss the advantages and possible applications of the method. Twenty unerupted third molars were sectioned transversally exposing coronal dentin surfaces. The microscopic mosaic method was used to generate a large field image with the resolution necessary to measure characteristics of dentin tubules. The AxioVision 4.7 software was used to control a motorized optical microscope and the process of acquiring approximately 400 small images to generate each dentin mosaic. An image analysis routine measured the number of tubules (NT) and the ratio between the total area of tubules and the area of the mosaic - the area fraction (AF) - of each mosaic. An automatic procedure transformed the mosaic image into a color map, providing a direct visual representation of tubule density through colors. The dentin maps were used for a comparative qualitative analysis of tubule density distribution of each sample. The results for NT (92450 to 196029 tubules/sample) and AF (4.12% to 11.10%) demonstrated a wide variation among dentin samples. The maps confirmed the microstructure variety, also revealing strong local variations in tubule density within each sample. The mapping method was able to perform dentin morphology characterization and is a valuable tool for producing a baseline for dentin adhesion studies. The method could be also useful in determining the real contribution of dentin structures to the final adhesion quality.

Stem/Progenitor Cell–Mediated De Novo Regeneration of Dental Pulp with Newly Deposited Continuous Layer of Dentin in an In Vivo Model

PubMed Central

Yamaza, Takayoshi; Shea, Lonnie D.; Djouad, Farida; Kuhn, Nastaran Z.; Tuan, Rocky S.; Shi, Songtao

2010-01-01

The ultimate goal of this study is to regenerate lost dental pulp and dentin via stem/progenitor cell–based approaches and tissue engineering technologies. In this study, we tested the possibility of regenerating vascularized human dental pulp in emptied root canal space and producing new dentin on existing dentinal walls using a stem/progenitor cell–mediated approach with a human root fragment and an immunocompromised mouse model. Stem/progenitor cells from apical papilla and dental pulp stem cells were isolated, characterized, seeded onto synthetic scaffolds consisting of poly-D,L-lactide/glycolide, inserted into the tooth fragments, and transplanted into mice. Our results showed that the root canal space was filled entirely by a pulp-like tissue with well-established vascularity. In addition, a continuous layer of dentin-like tissue was deposited onto the canal dentinal wall. This dentin-like structure appeared to be produced by a layer of newly formed odontoblast-like cells expressing dentin sialophosphoprotein, bone sialoprotein, alkaline phosphatase, and CD105. The cells in regenerated pulp-like tissue reacted positively to anti-human mitochondria antibodies, indicating their human origin. This study provides the first evidence showing that pulp-like tissue can be regenerated de novo in emptied root canal space by stem cells from apical papilla and dental pulp stem cells that give rise to odontoblast-like cells producing dentin-like tissue on existing dentinal walls. PMID:19737072

Comparative Analysis of Crack Propagation in Roots with Hand and Rotary Instrumentation of the Root Canal -An Ex-vivo Study.

PubMed

Kumari, Manju Raj; Krishnaswamy, Manjunath Mysore

2016-07-01

Success of any endodontic treatment depends on strict adherence to 'endodontic triad'. Preparation of root canal system is recognized as being one of the most important stages in root canal treatment. At times, we inevitably end up damaging root dentin which becomes a Gateway for infections like perforation, zipping, dentinal cracks and minute intricate fractures or even vertical root fractures, thereby resulting in failure of treatment. Several factors may be responsible for the formation of dentinal cracks like high concentration of sodium hypochlorite, compaction methods and various canal shaping methods. To compare and evaluate the effects of root canal preparation techniques and instrumentation length on the development of apical root cracks. Seventy extracted premolars with straight roots were mounted on resin blocks with simulated periodontal ligaments, exposing 1-2 mm of the apex followed by sectioning of 1mm of root tip for better visualization under stereomicroscope. The teeth were divided into seven groups of 10 teeth each - a control group and six experimental groups. Subgroup A & B were instrumented with: Stainless Steel hand files (SS) up to Root Canal Length (RCL) & (RCL -1 mm) respectively; sub group C & D were instrumented using ProTaper Universal (PTU) up to RCL and (RCL -1mm) respectively; subgroup E & F were instrumented using ProTaper Next (PTN) up to RCL & (RCL -1 mm) respectively. Stereomicroscopic images of the instrumentation sequence were compared for each tooth. The data was analyzed statistically using descriptive analysis by 'Phi' and 'Cramers' test to find out statistical significance between the groups. The level of significance was set at p< 0.05 using SPSS software. Stainless steel hand file group showed most cracks followed by ProTaper Universal & ProTaper Next though statistically not significant. Samples instrumented up to 1mm short of working length (RCL-1mm) showed lesser number of cracks. All groups showed cracks formation, the stainless steel group being the highest. Working 1mm short of apex reduces the incidence of crack formation.

Life history reconstruction of modern and fossil sockeye salmon ( Oncorhynchus nerka) by oxygen isotopic analysis of otoliths, vertebrae, and teeth: Implication for paleoenvironmental reconstructions

NASA Astrophysics Data System (ADS)

Zazzo, A.; Smith, G. R.; Patterson, W. P.; Dufour, E.

2006-09-01

We evaluate the use of oxygen isotope values of biogenic apatite for tracking freshwater to marine migration in modern and fossil Pacific sockeye salmon. Oxygen isotope analyses of otoliths, vertebrae, and teeth of three anadromous modern sockeye salmon from Alaska establish a basis for the interpretation of fossil vertebrae and tooth apatite from Pleistocene sockeye salmon of the Skokomish River Valley, Washington. High resolution δ18O profiles in salmon otoliths provide, at a monthly resolution, a detailed record of individual history including continental rearing, migration to sea, seasonal variation in sea surface temperatures during marine life, and spawning migration before capture. Pacific salmon teeth are constantly renewed with the last set of teeth forming under the influence of freshwater. Therefore, they do not allow inference concerning sea-run versus landlocked life history in fossil salmon. Salmon vertebrae are also ambiguous indicators of life history regarding fresh versus marine water because centra are minimally ossified in the freshwater stages of life and the outermost layer of vertebral bone might be resorbed to provide nutrients during the non-feeding phase of the spawning migration. Therefore, δ18O values of accretionary growth rings in sea-run salmon vertebrae are dominated by the marine signal only if they are not diagenetically altered in freshwater deposits. In Pleistocene sockeye reported here, neither the teeth nor vertebral apatite present clear marine δ18O values due to the combined effects of tooth replacement and diagenetic alteration of bone and dentine. δ18O(PO 4) values of fossil vertebrae are intermediate between δ18O(PO 4) values of enamel and basal tooth dentin. Assuming a similar rate of isotope exchange of vertebrae and dentine with freshwater during diagenesis, these results are interpreted to reflect formation of the teeth under the influence of freshwater, and formation of the vertebrae under the influence of oceanic water. Our approach demonstrates that when appropriate knowledge of tissue formation is available, isotopic differences between altered and unaltered tissue holds promise of distinguishing between marine and freshwater origin of the tissues.

In Vitro Study of Dentin Hypersensitivity Treated by 980-nm Diode Laser.

PubMed

Liu, Ying; Gao, Jie; Gao, Yan; Xu, Shuaimei; Zhan, Xueling; Wu, Buling

2013-01-01

To investigate the ultrastructural changes of dentin irradiated with 980-nm diode laser under different parameters and to observe the morphological alterations of odontoblasts and pulp tissue to determine the safety parameters of 980-nm diode laser in the treatment of dentin hypersensitivity (DH). Twenty extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into four areas and was irradiated by 980-nm diode laser under different parameters: Group A: control group, 0 J/cm(2); Group B: 2 W/CW (continuous mode), 166 J/cm(2); Group C: 3W/CW, 250 J/cm(2); and Group D: 4W/CW, 333 J/cm(2). Ten additional extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into two areas and was irradiated by 980-nm diode laser: Group E: control group, 0 J/cm(2); and Group F: 2.0 W/CW, 166 J/cm(2). The morphological alterations of the dentin surfaces and odontoblasts were examined with scanning electron microscopy (SEM), and the morphological alterations of the dental pulp tissue irradiated by laser were observed with an upright microscope. The study demonstrated that dentinal tubules can be entirely blocked after irradiation by 980-nm diode laser, regardless of the parameter setting. Diode laser with settings of 2.0 W and 980-nm sealed exposed dentin tubules effectively, and no significant morphological alterations of the pulp and odontoblasts were observed after irradiation. Irradiation with 980-nm diode laser could be effective for routine clinical treatment of DH, and 2.0W/CW (166 J/cm(2)) was a suitable energy parameter due to its rapid sealing of the exposed dentin tubules and its safety to the odontoblasts and pulp tissue.

Shear bond strength of composite to deep dentin after treatment with two different collagen cross-linking agents at varying time intervals.

PubMed

Srinivasulu, S; Vidhya, S; Sujatha, M; Mahalaxmi, S

2012-01-01

This in vitro study evaluated the shear bond strength of composite resin to deep dentin using a total etch adhesive after treatment with two collagen cross-linking agents at varying time intervals. Thirty freshly extracted human maxillary central incisors were sectioned longitudinally into equal mesial and distal halves (n=60). The proximal deep dentin was exposed, maintaining a remaining dentin thickness (RDT) of approximately 1 mm. The specimens were randomly divided into three groups based on the surface treatment of dentin prior to bonding as follows: group I (n=12, control): no prior dentin surface treatment; group II (n=24): dentin surface pretreated with 10% sodium ascorbate; and group III (n=24): dentin surface pretreated with 6.5% proanthocyanidin. Groups II and III were further subdivided into two subgroups of 12 specimens each, based on the pretreatment time of five minutes (subgroup A) and 10 minutes (subgroup B). Shear bond strength of the specimens was tested with a universal testing machine, and the data were statistically analyzed. Significantly higher shear bond strength to deep dentin was observed in teeth treated with 10% sodium ascorbate (group II) and 6.5% proanthocyanidin (group III) compared to the control group (group I). Among the collagen cross-linkers used, specimens treated with proanthocyanidin showed significantly higher shear bond strength values than those treated with sodium ascorbate. No significant difference was observed between the five-minute and 10-minute pretreatment times in groups II and III. It can be concluded that dentin surface pretreatment with both 10% sodium ascorbate and 6.5% proanthocyanidin resulted in significant improvement in bond strength of resin composite to deep dentin.

The effect of dentine surface preparation and reduced application time of adhesive on bonding strength.

PubMed

Saikaew, Pipop; Chowdhury, A F M Almas; Fukuyama, Mai; Kakuda, Shinichi; Carvalho, Ricardo M; Sano, Hidehiko

2016-04-01

This study evaluated the effects of surface preparation and the application time of adhesives on the resin-dentine bond strengths with universal adhesives. Sixty molars were cut to exposed mid-coronal dentine and divided into 12 groups (n=5) based on three factors; (1) adhesive: G-Premio Bond (GP, GC Corp., Tokyo, Japan), Clearfil Universal Bond (CU, Kuraray Noritake Dental Inc., Okayama, Japan) and Scotchbond Universal Adhesive (SB, 3M ESPE, St. Paul, MN, USA); (2) smear layer preparation: SiC paper ground dentine or bur-cut dentine; (3) application time: shortened time or as manufacturer's instruction. Fifteen resin-dentine sticks per group were processed for microtensile bond strength test (μTBS) according to non-trimming technique (1mm(2)) after storage in distilled water (37 °C) for 24h. Data were analyzed by three-way ANOVA and Dunnett T3 tests (α=0.05). Fractured surfaces were observed under scanning electron microscope (SEM). Another 12 teeth were prepared and cut into slices for SEM examination of bonded interfaces. μTBS were higher when bonded to SiC-ground dentine according to manufacturer's instruction. Bonding to bur-cut dentine resulted in significantly lower μTBS (p<0.000). Shortening the application time resulted in significantly lower bond strength for CU on SiC and GP on bur-cut dentine. SEM of fractured surfaces revealed areas with a large amount of porosities at the adhesive resin interface. This was more pronounced when adhesives were bonded with a reduced application time and on bur cut dentine. The performance of universal adhesives can be compromised on bur cut dentine and when applied with a reduced application time. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dicalcium phosphate (CaHPO4·2H2O) precipitation through ortho- or meta-phosphoric acid-etching: effects on the durability and nanoleakage/ultra-morphology of resin-dentine interfaces.

PubMed

Feitosa, Victor Pinheiro; Bazzocchi, Maria Giulia; Putignano, Angelo; Orsini, Giovanna; Luzi, Arlinda Luzi; Sinhoreti, Mário Alexandre Coelho; Watson, Timothy F; Sauro, Salvatore

2013-11-01

To compare the effects of two etching procedures using meta-phosphoric (MPA) or ortho-phosphoric acid (OPA) on dentine demineralisation, resin-dentine bonds durability and interface nanoleakage/ultra-morphology. Middle-dentine specimens were etched using 37% OPA (15s) or 40% MPA (60s) and submitted to infrared spectroscopy (FTIR) or ultra-morphology dye-assisted (calcium-staining) confocal microscopy (Ca-CLSM). A three-step etch-and-rinse adhesive was formulated, applied onto dentine and light-cured for 30s before composite build-up. After 24h, the dentine-bonded specimens were cut into 1mm(2) beams; half were immediately submitted to microtensile bond strength (μTBS) and half stored in DW for six months. The μTBS results were analysed with repeated-measures ANOVA and Tukey's test (p<0.05). Further teeth were bonded and prepared for interface nanoleakage/ultra-morphology confocal evaluation. FTIR and Ca-CLSM analyses showed dicalcium phosphate dihydrate (Brushite) precipitation in MPA-etched dentine and on the bottom (front of demineralisation) of the OPA-etched dentine. Statistical analysis showed similar μTBS for both etching procedures after 24h. The μTBS of specimens in OPA-group dropped significantly (p<0.05) after six month; the specimens in the MPA group showed no statistically difference (p>0.05). CLSM depicted no evident sign of nanoleakage within the resin-dentine interface of the MPA-treated specimens, while the specimens in OPA-group presented intense nanoleakage and interface degradation. The use of MPA (60s) as an alternative dentine conditioning agent in etch-and-rinse bonding procedures may be a suitable strategy to create more durable resin-dentine bonds. Copyright © 2013 Elsevier Ltd. All rights reserved.

In Vitro Study of Dentin Hypersensitivity Treated by 980-nm Diode Laser

PubMed Central

Liu, Ying; Gao, Jie; Gao, Yan; XU, Shuaimei; Zhan, Xueling; Wu, Buling

2013-01-01

Introduction: To investigate the ultrastructural changes of dentin irradiated with 980-nm diode laser under different parameters and to observe the morphological alterations of odontoblasts and pulp tissue to determine the safety parameters of 980-nm diode laser in the treatment of dentin hypersensitivity (DH). Methods: Twenty extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into four areas and was irradiated by 980-nm diode laser under different parameters: Group A: control group, 0 J/cm2; Group B: 2 W/CW (continuous mode), 166 J/cm2; Group C: 3W/CW, 250 J/cm2; and Group D: 4W/CW, 333 J/cm2. Ten additional extracted human third molars were selected to prepare dentin discs. Each dentin disc was divided into two areas and was irradiated by 980-nm diode laser: Group E: control group, 0 J/cm2; and Group F: 2.0 W/CW, 166 J/cm2. The morphological alterations of the dentin surfaces and odontoblasts were examined with scanning electron microscopy (SEM), and the morphological alterations of the dental pulp tissue irradiated by laser were observed with an upright microscope. Results: The study demonstrated that dentinal tubules can be entirely blocked after irradiation by 980-nm diode laser, regardless of the parameter setting. Diode laser with settings of 2.0 W and 980-nm sealed exposed dentin tubules effectively, and no significant morphological alterations of the pulp and odontoblasts were observed after irradiation. Conclusions: Irradiation with 980-nm diode laser could be effective for routine clinical treatment of DH, and 2.0W/CW (166 J/cm2) was a suitable energy parameter due to its rapid sealing of the exposed dentin tubules and its safety to the odontoblasts and pulp tissue. PMID:25606318

Inhibition of endogenous human dentin MMPs by Gluma

PubMed Central

Sabatini, Camila; Scheffel, Débora L.S.; Scheffel, Régis H.; Agee, Kelli A.; Rouch, Katelyn; Takahashi, Masahiro; Breschi, Lorenzo; Mazzoni, Annalisa; Tjäderhane, Leo; Tay, Franklin R.; Pashley, David H.

2014-01-01

Objective The objective of this study was to determine if Gluma dentin desensitizer (5.0% glutaraldehyde and 35% HEMA in water) can inhibit the endogenous MMPs of dentin matrices in 60 sec. and to evaluate its effect on dentin matrix stiffness and dry mass weight. Methods Dentin beams of 2×1×6 mm were obtained from extracted human third molars coronal dentin. To measure the influence of Gluma treatment time on total MMP activity of dentin, beams were dipped in 37% phosphoric acid (PA) for 15 sec. and rinsed in water. The acid-etched beams were then dipped in Gluma for 5, 15, 30 or 60 sec., rinsed in water and incubated into SensoLyte generic MMP substrate (AnaSpec, Inc.) for 60 min. Controls were dipped in water for 60 sec. Additional beams of 1×1×6 mm were completely demineralized in 37% PA for 18 h, rinsed and used to evaluate changes on the dry weight and modulus of elasticity (E) after 60 sec. of Gluma treatment followed by incubation in simulated body fluid buffer for zero, one or four weeks. E was measured by 3-pt flexure. Results Gluma treatment inhibited total MMP activity of acid-etched dentin by 44, 50, 84, 86 % after 5, 15, 30 or 60 sec. of exposure, respectively. All completely demineralized dentin beams lost stiffness after one and four weeks, with no significant differences between the control and Gluma-treated dentin. Gluma treatment for 60 sec. yielded significantly less dry mass loss than the control after four weeks. Significance The use of Gluma may contribute to the preservation of adhesive interfaces by its cross-linking and inhibitory properties of endogenous dentin MMPs. PMID:24846803

Effect of dentin biomodifiers on the immediate and long-term bond strengths of a simplified etch and rinse adhesive to dentin.

PubMed

Singh, Payal; Nagpal, Rajni; Singh, Udai Pratap

2017-08-01

This in vitro study evaluated the effect of dentin biomodifiers on the immediate and long-term bond strengths of a simplified etch and rinse adhesive to dentin. Flat coronal dentin surfaces were prepared in 120 extracted human molars. Teeth were randomly divided into 5 groups ( n = 24) according to 5 different surface pre-treatments: No pre-treatment (control); 1M carbodiimide (EDC); 0.1% epigallocatechin-3-gallate (EGCG); 2% minocycline (MI); 10% sodium ascorbate (SA). After surface pre-treatment, adhesive (Adper Single Bond 2 [SB], 3M ESPE) was applied. Composite was applied into transparent plastic tubes (2.5 mm in diameter), which was placed over the bonded dentin surface. From each group, 10 samples were subjected to shear bond strength (SBS) evaluation at 24 hours (immediate) and remaining 10 samples were tested after 6 months (delayed). Additionally, 4 samples per group were subjected to scanning electron microscopic analysis for observation of resin-dentin interface. The data were statistically analysed with Shaperio‑Wilk W test, 2-way analysis of variance (ANOVA), and post hoc Tukey's test. At 24 hours, SBS of all surface pre-treatment groups were comparable with the control group, with significant differences found between EDC and SA groups only ( p = 0.009). After 6 months storage, EDC, EGCG, and MI pre-treatments preserved the resin-dentin bond strength with no significant fall. Dentin pre-treatment with all the dentin biomodifiers except SA resulted in significant preservation of resin-dentin bond over 6 months storage period, without negatively affecting the immediate bond strength of the etch and rinse adhesive tested.

Effect of propolis gel on the in vitro reduction of dentin permeability

PubMed Central

SALES-PERES, Silvia Helena de Carvalho; de CARVALHO, Flávia Negreiros; MARSICANO, Juliane Avansini; MATTOS, Maria Cecília; PEREIRA, José Carlos; FORIM, Moacir Rossi; da SILVA, Maria Fatima das Graças Fernandes

2011-01-01

Objective The aim of this study was to evaluate the capacity of potassium oxalate, fluoride gel and two kinds of propolis gel to reduce the hydraulic conductance of dentin, in vitro. Material and Methods The methodology used for the measurement of hydraulic conductance of dentin in the present study was based on a model proposed in literature. Thirty-six 1-mm-thick dentin discs, obtained from extracted human third molars were divided into 4 groups (n=9). The groups corresponded to the following experimental materials: GI-10% propolis gel, pH 4.1; GII-30% propolis gel; GIII-3% potassium oxalate gel, pH 4,1; and GIV-1.23% fluoride gel, pH 4.1, applied to the dentin under the following surface conditions: after 37% phosphoric acid and before 6% citric acid application. The occluding capacity of the dentin tubules was evaluated using scanning electron microscopy (SEM) at ×500, ×1,000 and ×2,000 magnifications. Data were analyzed statistically by two-way ANOVA and Tukey's test at 5% significance level. Results Groups I, II, III, IV did not differ significantly from the others in any conditions by reducing in hydraulic conductance. The active agents reduced dentin permeability; however they produced the smallest reduction in hydraulic conductance when compared to the presence of smear layer (P<0.05). The effectiveness in reducing dentin permeability did not differ significantly from 10% or 30% propolis gels. SEM micrographs revealed that dentin tubules were partially occluded after treatment with propolis. Conclusions Under the conditions of this study, the application of 10% and 30% propolis gels did not seem to reduce the hydraulic conductance of dentin in vitro, but it showed capacity of partially obliterating the dentin tubules. Propolis is used in the treatment of different oral problems without causing significant great collateral effects, and can be a good option in the treatment of patients with dentin sensitivity. PMID:21956588

Penetration pattern of rhodamine dyes into enamel and dentin: confocal laser microscopy observation.

PubMed

Kwon, S R; Wertz, P W; Li, Y; Chan, D C N

2012-02-01

Enamel and dentin are susceptible to extrinsic and intrinsic stains. The purposes of this study were to determine the penetration pattern of Rhodamine B and dextran-conjugated Rhodamine B into the enamel and dentin as observed by confocal laser microscopy and to relate it to the penetration pattern of hydrogen peroxide commonly used as an active ingredient in tooth-whitening agents and high-molecular-weight staining molecules. Eighteen recently extracted human maxillary anterior teeth were used. Teeth were cleaned and painted with nail varnish except for the crown area above the cemento-enamel junction (CEJ). The painted teeth were then immersed in Rhodamine B and dextran-conjugated Rhodamine B (70 000 MW) for 4, 7, 10 and 15 days. Teeth were sliced to 3 mm thickness in transverse plane and mounted on a glass slide just prior to observation with confocal laser microscopy. Rhodamine B and dextran-conjugated Rhodamine B readily penetrated into the enamel and dentin when exposed for 4 and 7 days, respectively. Rhodamine B penetrated along the interprismatic spaces of the enamel into the dentin. The penetration was accentuated in sections with existing crack lines in the enamel. Rhodamine B was readily absorbed into the dentinal tubules at the dentino-enamel junction and continued to penetrate through the dentin via the dentinal tubules into the pre-dentin. Within the limitations of this study, it is concluded that Rhodamine B and dextran-conjugated Rhodamine B when applied to the external surface of the tooth readily penetrate into the enamel and dentin via the interprismatic spaces in the enamel and dentinal tubules in the dentin, suggesting that stain molecules and bleaching agents possibly exhibit similar penetration pathways. © 2011 The Authors. ICS © 2011 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

The use of acetone to enhance the infiltration of HA nanoparticles into a demineralized dentin collagen matrix.

PubMed

Besinis, Alexandros; van Noort, Richard; Martin, Nicolas

2016-03-01

This study investigates the role of acetone, as a carrier for nano-hydroxyapatite (nano-HA) in solution, to enhance the infiltration of fully demineralized dentin with HA nanoparticles (NPs). Dentin specimens were fully demineralized and subsequently infiltrated with two types of water-based nano-HA solutions (one containing acetone and one without). Characterization of the dentin surfaces and nano-HA particles was performed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The surface wettability and infiltration capacity of the nano-HA solutions were quantified by means of contact angle measurements and energy dispersive X-ray spectroscopy (EDS), respectively. Contact angle measurements were taken at baseline and repeated at regular intervals to assess the effect of acetone. The P and Ca levels of infiltrated dentin specimens were measured and compared to sound dentin and non-infiltrated controls. The presence of acetone resulted in an eight-fold decrease in the contact angles of the nano-HA solutions recorded on the surface of demineralized dentin compared to nano-HA solutions without acetone (one-way ANOVA, p<0.05). Perfect wetting of the demineralized dentin surface was achieved 5min after the application of the nano-HA solution containing acetone. Infiltration of demineralized dentin with the nano-HA solution containing acetone restored the lost mineral content by 50%, whereas the mean mineralization values for P and Ca in dentin treated with the acetone-free nano-HA solution were less than 6%. Acetone was shown to act as a vehicle to enhance the capacity to infiltrate demineralized dentin with HA NPs. The successful infiltration of dentin collagen with HA NPs provides a suitable scaffold, whereby the infiltrated HA NPs have the potential to act as seeds that may initiate heterogenous mineral growth when exposed to an appropriate mineral-rich environment. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Nanoindentation hardness of intertubular dentin in sound, demineralized and natural caries-affected dentin.

PubMed

Joves, Gerardo José; Inoue, Go; Sadr, Alireza; Nikaido, Toru; Tagami, Junji

2014-04-01

The purpose of this study was to investigate the mechanical properties of intertubular dentin in sound, natural caries-affected (NCAD) and artificial caries-affected dentin (ACAD) using nanoindentation. Non-caries molars and caries molars with International Caries Detection and Assessment System (ICDAS II) score 5 at the occlusal site were used and caries was excavated using a spoon excavator, a round bur at low speed without water and a dye solution as guidance to detect the infected tissue. Specimens with remaining dentin thickness (RDT) >2mm were selected. ACAD teeth were created from sound teeth over 7 days in a demineralizing solution. Specimens were embedded into plastic rings with acrylic resin and then sagittal mesial-distal sectioned from crown to the long axis of the root under cooling water using a low-speed diamond blade. The surface of interest was fine polished sequentially. Hardness measurement was performed within an axial depth of 1000μm with at least of 320 indentations on each sample. Mann-Whitney U Test was used to compare the hardness as the variable among different dentin types (SOUND, NCAD and ACAD) at each dentin depth level. There was no significant difference in nanohardness between NCAD and ACAD up to a depth of 130μm (p>0.05). NCAD consistently showed lower hardness. ACAD showed no significant difference in hardness with SOUND dentin beyond 190μm (p<0.05). The lesion front in ACAD was considered to be located around the depth of 180μm. Natural and artificial caries-affected dentin tissues were superficially comparable in intertubular nanohardness. There is a certain layer within the natural caries-affected dentin with higher hardness; however the long-term effects of caries beneath the lesion extend deeply through intertubular dentin. Sound dentin at deep areas (close to the pulp chamber) is considered to be soft. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biomechanical studies on the effect of iatrogenic dentin removal on vertical root fractures

PubMed Central

Ossareh, A.; Rosentritt, M.; Kishen, A.

2018-01-01

Introduction: The aim of this study was to understand the mechanism by which iatrogenic root dentin removal influences radicular stress distribution and subsequently affects the resistance to vertical root fractures (VRF) in endodontically treated teeth. Materials and Methods: The experiments were conducted in two phases. Phase 1: freshly extracted premolar teeth maintained in phosphate-buffered saline were instrumented to simulate three different degrees of dentin removal, designated as low, medium, and extreme groups. Micro-Ct analyzes were performed to quantitatively determine: (a) the amount of dentin removed, (b) the remaining dentin volume, and (c) the moment of inertia of root dentin. The specimens were then subjected to thermomechanical cycling and continuous loading to determine (a) the mechanical load to fracture and (b) dentin microcracking (fractography) using scanning electron microscopy. Phase 2: Finite element analysis was used to evaluate the influence of dentin removal on the stress distribution pattern in root dentin. The data obtained were analyzed using one-way ANOVA and Tukey's post hoc test (P < 0.05). Results: Phase 1: A significantly greater volume of dentin was removed from teeth in extreme group when compared to low group (P < 0.01). The mechanical analysis showed that the load to fracture was significantly lower in teeth from extreme group (P < 0.05). A linear relationship was observed between the moment of inertia and load to fracture in all experimental groups (R2 = 0.52). Fractography showed that most microcracks were initiated from the root canal walls in extreme group. Phase 2: The numerical analysis showed that the radicular stress distribution increased apically and buccolingually with greater degree of root canal dentin removal. Conclusions: The combined experimental/numerical analyses highlighted the influence of remaining root dentin volume on the radicular bending resistance, stress distribution pattern, and subsequent propensity to VRF. PMID:29899632

Effect of conditioning solutions containing ferric chloride on dentin bond strength and collagen degradation.

PubMed

Rodrigues, Raquel Viana; Giannini, Marcelo; Pascon, Fernanda Miori; Panwar, Preety; Brömme, Dieter; Manso, Adriana Pigozzo; Carvalho, Ricardo Marins

2017-10-01

To investigate the effects of conditioning solutions containing ferric chloride (FeCl 3 ) on resin-dentin bond strength; on protection of dentin collagen against enzymatic degradation and on cathepsin-K (CT-K) activity. Conditioning solutions were prepared combining citric acid (CA) and anhydrous ferric chloride (FeCl 3 ) in different concentrations. The solutions were applied to etch flat dentin surfaces followed by bonding with adhesive resin. Phosphoric acid (PA) gel etchant was used as control. The microtensile bond strength (μTBS) was tested after 24h of storage in water and after 9 months of storage in phosphate buffer saline. Dentin slabs were demineralized in 0.5M EDTA, pre-treated or not with FeCl 3 and incubated with CT-K. The collagenase activity on dentin collagen matrix was examined and characterized by SEM. Additional demineralized dentin slabs were treated with the conditioning solutions, and the amount of Fe bound to collagen was determined by EDX. The activity of CT-K in the presence of FeCl 3 was monitored fluorimetrically. Data were analyzed by ANOVA followed by post-hoc tests as required (α=5%). Slightly higher bond strengths were obtained when dentin was conditioned with 5% CA/0.6% FeCl 3 and 5% CA-1.8%FeCl 3 regardless of storage time. Bond strengths reduced significantly for all tested conditioners after 9 months of storage. Treating dentin with 1.8% FeCl 3 was effective to preserve the structure of collagen against CT-K. EDX analysis revealed binding of Fe-ions to dentin collagen after 15s immersion of demineralized dentin slabs into FeCl 3 solutions. FeCl 3 at concentration of 0.08% was able to suppress CT-K activity. This study shows that FeCl 3 binds to collagen and offers protection against Cat-K degradation. Mixed solutions of CA and FeCl 3 may be used as alternative to PA to etch dentin in resin-dentin bonding with the benefits of preventing collagen degradation. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Sealing properties of a self-etching primer system to normal caries-affected and caries-infected dentin.

PubMed

Lee, Kwang-Won; Son, H-H; Yoshiyama, Masatoshi; Tay, Franklin R; Carvalho, Ricardo M; Pashley, David H

2003-09-01

To compare the ability of an experimental antibacterial self-etching primer adhesive system to seal exposure sites in normal, caries-affected and caries-infected human dentin. 30 extracted human third molars were used within 1 month of extraction. 10 intact normal teeth comprised the normal group. 20 teeth with occlusal caries that radiographically extended halfway to the pulp were excavated using caries-detector solution (CDS) and a #4 round carbide bur in a slowspeed handpiece. Half of those teeth were fully excavated free of CDS-stained material without exposing the pulp, and were designated as the caries-affected dentin group. The remaining 10 teeth were excavated as close to the pulp as possible without obtaining an exposure, but whose dentin continued to stain red with CDS; this group was designated as the caries-infected dentin group. The remaining dentin thickness in all of the specimens in the other two groups was then reduced to the same extent as the caries-infected group. Direct exposures of the pulp chamber were made with a 1/4 round bur in the normal dentin or a 25 gauge needle in the other two groups. After measuring the fluid flow through the exposure, the sites were then sealed with an experimental antibacterial fluoride-containing self-etching primer adhesive systems (ABF). Fluid conductance was remeasured every week for 16 weeks. The fluid conductance through the exposure fell 99% in all groups following resin sealing. The seals of normal and caries-affected dentin remained relatively stable over the 16 weeks, while the seals of caries-infected dentin gradually deteriorated, reaching significance at 8 weeks. TEM examination revealed very thin (ca. 0.5 mm) hybrid layers in normal dentin, 3-4 microm thick hybrid layers in caries-affected dentin and 40 microm thick hybrid layers in caries-infected dentin. The tubules of caries-infected dentin were enlarged and filled with bacteria. Resin tags passed around these bacteria in the top 20-40 microm thereby encapsulating them in resin.

Fluorine analysis of human dentin surrounding resin composite after fluoride application by μ-PIGE/PIXE analysis

NASA Astrophysics Data System (ADS)

Okuyama, Katsushi; Komatsu, Hisanori; Yamamoto, Hiroko; Pereira, Patricia N. R.; Bedran-Russo, Ana K.; Nomachi, Masaharu; Sato, Takahiro; Sano, Hidehiko

2011-10-01

The use of fluoride for the prevention of caries is based on the transformation of hydroxylapatite to fluoroapatite in the presence of fluoride ions, thereby strengthening tooth structure. Adhesion of dentin and resin composite (tooth-colored restoration material) requires a dentin bonding system, since resin composite is not able to adhere to dentin directly. Demineralization of dentin by acid etching is an important step in the dentin bonding system, however, demineralization also introduces weaknesses in tooth structure. If the demineralized dentin could be strengthened by the application of fluoride, then the dentin-resin composite bond strength might also improve. To test this hypothesis, the present study evaluated the influence of fluoride applications on the strength of the dentin-resin composite bond by (1) tensile strength testing analyses, (2) SEM analyses of tooth structure, and (3) detection of calcium (Ca) and fluorine (F) distribution patterns by micro proton-induced X-ray emission (μ-PIXE) and micro proton-induced gamma-ray emission (μ-PIGE) analyses conducted at the Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) at the Takasaki Advanced Radiation Research Institute (TARRI). In this study, the dentin in extracted human molars was exposed by grinding and the dentin was etched with 35% phosphoric acid. Fluoride was applied at two concentrations, 0.022% (100 ppm F) and 2.21% (10,000 ppm F) NaF solution, for two time periods, 30 and 60 s, prior to bonding the resin composite with the treated dentin. Controls were prepared in the same manner, but without the fluoride application. Bond strength was measured with a micro-tensile testing unit, and the fluorine and calcium distributions at the interface between dentin and resin composite were detected by μ-PIGE and μ-PIXE analysis, respectively. Results indicate that the 10,000 ppm F applications resulted in higher bond strengths than observed in either the 100 ppm F applications or the control group. In addition, PIGE analyses showed high concentrations of fluorine in the hybrid bonding layer of the 10,000 ppm F samples, suggesting that the fluorine contributes to the strength of the dentin-resin composite bond. Detection of fluoroapatite within the hybrid bonding layer suggests that bond strength involves remineralization processes.

Dependence of cell adhesion on extracellular matrix materials formed on pore bridge boundaries by nanopore opening and closing geometry.

PubMed

Kim, Sueon; Han, Dong Yeol; Chen, Zhenzhong; Lee, Won Gu

2018-04-30

In this study, we report experimental results for characterization of the growth and formation of pore bridge materials that modified the adhesion structures of cells cultured on nanomembranes with opening and closing geometry. To perform the proof-of-concept experiments, we fabricated two types of anodized alumina oxide substrates with single-sided opening (i.e., one side open, but closed at the other side) and double-sided opening (i.e., both sides open). In our experiment, we compared the densities of pores formed and of bridge materials which differently act as connective proteins depending on the size of pores. The results show that the pore opening geometry can be used to promote the net contact force between pores, resulting in the growth and formation of pore bridge materials before and after cell culture. The results also imply that the bridge materials can be used to attract the structural protrusion of filopodia that can promote the adhesion of cell-to-cell and cell-to-pore bridge. It is observed that the shape and size of cellular structures of filopodia depend on the presence of pore bridge materials. Overall, this observation brought us a significant clue that cells cultured on nanopore substrates would change the adhesion property depending on not only the formation of nanopores formed on the surface of topological substrates, but also that of pore bridge materials by its morphological growth.

A comparative in vitro study investigating the occlusion and mineralization properties of commercial toothpastes in a four-day dentin disc model.

PubMed

Parkinson, Charles R; Willson, Richard J

2011-01-01

The objective of this study was to evaluate the relative level of dentin tubule occlusion and dentin mineralization conferred by a 5% w/w calcium sodium phosphosilicate (45S5)/1450 ppm fluoride toothpaste in comparison to a range of commercial toothpastes reported to occlude dentin tubules. Two separate experiments were employed to (i) determine the level of dentin tubule occlusion, and (ii) explore the change in dentin mineralization conferred by a number of marketed toothpastes and controls, following twice-daily brushing in a longitudinal, acid challenge-based, dentin disc model. In Study I, 192 bovine dentin discs, polished and etched in citric acid to provide a smooth dentin surface with patent tubules, were divided into eight treatment groups and subjected to brushing with one of seven test toothpastes or deionized water over four days. Prior to and between treatments, the dentin samples were stored in saliva. The test products were fluoridated toothpastes containing: calcium sodium phosphosilicate (45S5); strontium acetate; arginine/calcium carbonate; amine fluoride; calcium sulphate/diphosphate; stannous fluoride; casein stabilized amorphous calcium phosphate toothpaste; and a non-occluding negative control, deionized water. At the end of each treatment day (1 though 4), one group of samples was removed for scanning electron microscopy (SEM) analysis and graded on a categorical visual scale to assess the level of dentin tubule occlusion. A subset of samples from Study I was also cross-sectioned and examined using SEM. For the exploratory mineralization study (Study II), 120 dentin specimens were prepared as previously described and divided into four treatment groups consisting of A, C, F, and a tooth sealant varnish (I), and subjected to the treatment regimen described in Study I. The dentin samples were assessed for changes in surface microhardness using an indenter fitted with a Knoop probe and the level of dentin occlusion. In Study I, the 5% w/w calcium sodium phosphosilicate/1450 ppm fluoride-containing toothpaste (A), the stannous fluoride-containing toothpaste (F), and the strontium acetate-containing toothpaste (B) delivered the highest level of occlusion following four days of twice-daily brushing and a twice-daily acid challenge on days 3 and 4. Surface analysis of a subset of Study I samples, following four days of treatment, indicated that the 5% w/w calcium sodium phosphosilicate/1450 ppm fluoride-containing toothpaste formed a distinct layer at the surface of dentin. For Study II, surface microhardness analysis revealed that the 5% w/w calcium sodium phosphosilicate/1450 ppm fluoride-containing toothpaste (A) delivered significantly more surface hardening then the control or competitor toothpastes on days 2 and 4. Desensitizing toothpastes reported to operate by an occlusion mechanism have been observed to confer varying degrees of dentin tubule occlusion and dentin mineralization over four days in an acid challenge-based in vitro model. A 5% w/w calcium sodium phosphosilicate/1450 ppm fluoride-containing toothpaste was observed to impart a significant level of dentin tubule occlusion and surface hardening, and form durable occlusive deposits following four days of twice-daily brushing in vitro.

Multiple essential MT1-MMP functions in tooth root formation, dentinogenesis, and tooth eruption

PubMed Central

Wimer, H.F.; Yamada, S.S.; Yang, T.; Holmbeck, K.; Foster, B.L.

2016-01-01

Membrane-type matrix metalloproteinase 1 (MT1-MMP) is a transmembrane zinc-endopeptidase that breaks down extracellular matrix components, including several collagens, during tissue development and physiological remodeling. MT1-MMP-deficient mice (MT1-MMP−/−) feature severe defects in connective tissues, such as impaired growth, osteopenia, fibrosis, and conspicuous loss of molar tooth eruption and root formation. In order to define the functions of MT1-MMP during root formation and tooth eruption, we analyzed the development of teeth and surrounding tissues in the absence of MT1-MMP. In situ hybridization showed that MT1-MMP was widely expressed in cells associated with teeth and surrounding connective tissues during development. Multiple defects in dentoalveolar tissues were associated with loss of MT1-MMP. Root formation was inhibited by defective structure and function of Hertwig's epithelial root sheath (HERS). However, no defect was found in creation of the eruption pathway, suggesting that tooth eruption was hampered by lack of alveolar bone modeling/remodeling coincident with reduced periodontal ligament (PDL) formation and integration with the alveolar bone. Additionally, we identified a significant defect in dentin formation and mineralization associated with the loss of MT1-MMP. To segregate these multiple defects and trace their cellular origin, conditional ablation of MT1-MMP was performed in epithelia and mesenchyme. Mice featuring selective loss of MT1-MMP activity in the epithelium were indistinguishable from wild type mice, and importantly, featured a normal HERS structure and molar eruption. In contrast, selective knock-out of MT1-MMP in Osterix-expressing mesenchymal cells, including osteoblasts and odontoblasts, recapitulated major defects from the global knock-out including altered HERS structure, short roots, defective dentin formation and mineralization, and reduced alveolar bone formation, although molars were able to erupt. These data indicate that MT1-MMP activity in the dental mesenchyme, and not in epithelial-derived HERS, is essential for proper tooth root formation and eruption. In summary, our studies point to an indispensable role for MT1-MMP-mediated matrix remodeling in tooth eruption through effects on bone formation, soft tissue remodeling and organization of the follicle/PDL region. PMID:26780723

Magnesium-Containing Nanostructured Hybrid Scaffolds for Enhanced Dentin Regeneration

PubMed Central

Qu, Tiejun; Jing, Junjun; Jiang, Yong; Taylor, Robert J.; Feng, Jian Q.; Geiger, Benjamin

2014-01-01

Dental caries is one of the most prevalent chronic diseases in the United States, affecting 92% of adults aged 20–64 years. Scaffold-based tissue engineering represents a promising strategy to replace damaged dental structures and restore their biological functions. Current single-component scaffolding materials used for dental tissue regeneration, however, cannot provide the proper microenvironment for dental stem/progenitor cell adhesion, proliferation, and differentiation; new biomimetic hybrid scaffolds are needed to promote better dental tissue formation. In this work, we developed a biomimetic approach to prepare three-dimensional (3D) nanofibrous gelatin/magnesium phosphate (NF-gelatin/MgP) hybrid scaffolds. These scaffolds not only mimic the nanostructured architecture and the chemical composition of natural dentin matrices but also constantly present favorable chemical signals (Mg ions) to dental pulp stem cells (DPSCs), thus providing a desirable microenvironment to facilitate DPSC proliferation, differentiation, and biomineralization. Synthesized hybrid NF-gelatin/MgP possesses natural extracellular matrix (ECM)-like architecture, high porosity, high pore interconnectivity, well-defined pore size, and controlled Mg ion release from the scaffold. Adding MgP into NF-gelatin also increased the mechanical strength of the hybrid scaffold. The sustained release of Mg ions from the NF-gelatin/MgP (MgP=10% wt/wt) scaffold significantly enhanced the proliferation, differentiation, and biomineralization of human DPSCs in vitro. The alkaline phosphatase (ALP) activity and the gene expressions for odontogenic differentiation (collagen I [Col I], ALP, osteocalcin [OCN], dentin sialophosphoprotein [DSPP], and dentin matrix protein 1 [DMP1]) were all significantly higher (p<0.05) in the NF-gelatin/MgP group than in the NF-gelatin group. Those results were further confirmed by hematoxylin and eosin (H&E) and von Kossa staining, as shown by greater ECM secretion and mineral deposition in the hybrid scaffold. Consistent with the in vitro study, the DPSCs/NF-gelatin/MgP constructs produced greater ECM deposition, hard tissue formation, and expression of marker proteins (DSPP, DMP1, Col I) for odontogenic differentiation than did the DPSCs/NF-gelatin after 5 weeks of ectopic implantation in rude mice. The controlled release of metallic ions from biomimetic nanostructured hybrid scaffolds, therefore, is a promising approach to enhancing the biological capability of the scaffolds for dental tissue regeneration. PMID:24593189

Magnesium-containing nanostructured hybrid scaffolds for enhanced dentin regeneration.

PubMed

Qu, Tiejun; Jing, Junjun; Jiang, Yong; Taylor, Robert J; Feng, Jian Q; Geiger, Benjamin; Liu, Xiaohua

2014-09-01

Dental caries is one of the most prevalent chronic diseases in the United States, affecting 92% of adults aged 20-64 years. Scaffold-based tissue engineering represents a promising strategy to replace damaged dental structures and restore their biological functions. Current single-component scaffolding materials used for dental tissue regeneration, however, cannot provide the proper microenvironment for dental stem/progenitor cell adhesion, proliferation, and differentiation; new biomimetic hybrid scaffolds are needed to promote better dental tissue formation. In this work, we developed a biomimetic approach to prepare three-dimensional (3D) nanofibrous gelatin/magnesium phosphate (NF-gelatin/MgP) hybrid scaffolds. These scaffolds not only mimic the nanostructured architecture and the chemical composition of natural dentin matrices but also constantly present favorable chemical signals (Mg ions) to dental pulp stem cells (DPSCs), thus providing a desirable microenvironment to facilitate DPSC proliferation, differentiation, and biomineralization. Synthesized hybrid NF-gelatin/MgP possesses natural extracellular matrix (ECM)-like architecture, high porosity, high pore interconnectivity, well-defined pore size, and controlled Mg ion release from the scaffold. Adding MgP into NF-gelatin also increased the mechanical strength of the hybrid scaffold. The sustained release of Mg ions from the NF-gelatin/MgP (MgP=10% wt/wt) scaffold significantly enhanced the proliferation, differentiation, and biomineralization of human DPSCs in vitro. The alkaline phosphatase (ALP) activity and the gene expressions for odontogenic differentiation (collagen I [Col I], ALP, osteocalcin [OCN], dentin sialophosphoprotein [DSPP], and dentin matrix protein 1 [DMP1]) were all significantly higher (p<0.05) in the NF-gelatin/MgP group than in the NF-gelatin group. Those results were further confirmed by hematoxylin and eosin (H&E) and von Kossa staining, as shown by greater ECM secretion and mineral deposition in the hybrid scaffold. Consistent with the in vitro study, the DPSCs/NF-gelatin/MgP constructs produced greater ECM deposition, hard tissue formation, and expression of marker proteins (DSPP, DMP1, Col I) for odontogenic differentiation than did the DPSCs/NF-gelatin after 5 weeks of ectopic implantation in rude mice. The controlled release of metallic ions from biomimetic nanostructured hybrid scaffolds, therefore, is a promising approach to enhancing the biological capability of the scaffolds for dental tissue regeneration.

[Dentinal hypersensitivity in periodontal disease. Aetiology Aetiology--management].

PubMed

Andronikaki-Faldani, A; Kamma, I

1988-01-01

The exposure of dentine has a multifactoral aetiology and pain may frequently be elicited by a number of stimuli. Management of dentinal hypersensitivity tends to be empirical because of the lack of knowledge concerning the mechanism of pain transmission through dentine. Nevertheless, whichever theory proves to be correct, occlusion of dentinal tubules would appear an essential prerequisite for an effective desensitising agent. A large number of compounds as well as iontophoresis have been employed in the management of dentinal hypersensitivity. These desensitising agents are: sodium, fluoride, stannous fluoride, sodium monofluorophosphate, strontium chloride, calcium hydroxide, potassium nitrate, silver nitrate, formalin, corticosteroids, resins, varnishes and glass ionomers. The most effective of the compounds mentioned above, are fluorides used as gels, varnishes, mouthwashes or toothpastes, strontium chloride and potassium nitrate.

Automated recording of bridge inspection data in the Pontis format.

DOT National Transportation Integrated Search

1995-04-01

A large percentage of bridges in the state of Iowa are classified as structurally or fiinctionally : deficient. These bridges annually compete for a share of Iowa's limited transportation budget. To : avoid an increase in the number of deficient brid...

DNA double-strand breaks and Aurora B mislocalization induced by exposure of early mitotic cells to H2O2 appear to increase chromatin bridges and resultant cytokinesis failure.

PubMed

Cho, Min-Guk; Ahn, Ju-Hyun; Choi, Hee-Song; Lee, Jae-Ho

2017-07-01

Aneuploidy, an abnormal number of chromosomes that is a hallmark of cancer cells, can arise from tetraploid/binucleated cells through a failure of cytokinesis. Reactive oxygen species (ROS) have been implicated in various diseases, including cancer. However, the nature and role of ROS in cytokinesis progression and related mechanisms has not been clearly elucidated. Here, using time-lapse analysis of asynchronously growing cells and immunocytochemical analyses of synchronized cells, we found that hydrogen peroxide (H 2 O 2 ) treatment at early mitosis (primarily prometaphase) significantly induced cytokinesis failure. Cytokinesis failure and the resultant formation of binucleated cells containing nucleoplasmic bridges (NPBs) seemed to be caused by increases in DNA double-strand breaks (DSBs) and subsequent unresolved chromatin bridges. We further found that H 2 O 2 induced mislocalization of Aurora B during mitosis. All of these effects were attenuated by pretreatment with N-acetyl-L-cysteine (NAC) or overexpression of Catalase. Surprisingly, the PARP inhibitor PJ34 also reduced H 2 O 2 -induced Aurora B mislocalization and binucleated cell formation. Results of parallel experiments with etoposide, a topoisomerase IIα inhibitor that triggers DNA DSBs, suggested that both DNA DSBs and Aurora B mislocalization contribute to chromatin bridge formation. Aurora B mislocalization also appeared to weaken the "abscission checkpoint". Finally, we showed that KRAS-induced binucleated cell formation appeared to be also H 2 O 2 -dependent. In conclusion, we propose that a ROS, mainly H 2 O 2 increases binucleation through unresolved chromatin bridges caused by DNA damage and mislocalization of Aurora B, the latter of which appears to augment the effect of DNA damage on chromatin bridge formation. Copyright © 2017 Elsevier Inc. All rights reserved.

Structure and magnetic properties of an unprecedented syn-anti μ-nitrito-1κO:2κO' bridged Mn(III)-salen complex and its isoelectronic and isostructural formate analogue.

PubMed

Kar, Paramita; Biswas, Rituparna; Drew, Michael G B; Ida, Yumi; Ishida, Takayuki; Ghosh, Ashutosh

2011-04-07

The preparation, crystal structures and magnetic properties of two new isoelectronic and isomorphous formate- and nitrite-bridged 1D chains of Mn(III)-salen complexes, [Mn(salen)(HCOO)](n) (1) and [Mn(salen)(NO(2))](n) (2), where salen is the dianion of N,N'-bis(salicylidene)-1,2-diaminoethane, are presented. The structures show that the salen ligand coordinates to the four equatorial sites of the metal ion and the formate or nitrite ions coordinate to the axial positions to bridge the Mn(III)-salen units through a syn-antiμ-1κO:2κO' coordination mode. Such a bridging mode is unprecedented in Mn(III) for formate and in any transition metal ion for nitrite. Variable-temperature magnetic susceptibility measurements of complexes 1 and 2 indicate the presence of ferromagnetic exchange interactions with J values of 0.0607 cm(-1) (for 1) and 0.0883 cm(-1) (for 2). The ac measurements indicate negligible frequency dependence for 1 whereas compound 2 exhibits a decrease of χ(ac)' and a concomitant increase of χ(ac)'' on elevating frequency around 2 K. This finding is an indication of slow magnetization reversal characteristic of single-chain magnets or spin-glasses. The μ-nitrito-1κO:2κO' bridge seems to be a potentially superior magnetic coupler to the formate bridge for the construction of single-molecule/-chain magnets as its coupling constant is greater and the χ(ac)' and χ(ac)'' show frequency dependence. © The Royal Society of Chemistry 2011

Adhesive sealing of dentin surfaces in vitro: A review

PubMed Central

Abu-Nawareg, Manar M; Zidan, Ahmed Z; Zhou, Jianfeng; Agee, Kelli; Chiba, Ayaka; Tagami, Jungi; Pashley, David H

2016-01-01

Purpose The purpose of this review is to describe the evolution of the use of dental adhesives to form a tight seal of freshly prepared dentin to protect the pulp from bacterial products, during the time between crown preparation and final cementum of full crowns. The evolution of these “immediate dentin sealants” follows the evolution of dental adhesives, in general. That is, they began with multiple-step, etch-and-rinse adhesives, and then switched to the use of simplified adhesives. Methods Literature was reviewed for evidence that bacteria or bacterial products diffusing across dentin can irritate pulpal tissues before and after smear layer removal. Smear layers can be solubilized by plaque organisms within 7–10 days if they are directly exposed to oral fluids. It is likely that smear layers covered by temporary restorations may last more than one month. As long as smear layers remain in place, they can partially seal dentin. Thus, many in vitro studies evaluating the sealing ability of adhesive resins use smear layer-covered dentin as a reference condition. Surprisingly, many adhesives do not seal dentin as well as do smear layers. Results Both in vitro and in vivo studies show that resin-covered dentin allows dentinal fluid to cross polymerized resins. The use of simplified single bottle adhesives to seal dentin was a step backwards. Currently, most authorities use either 3-step adhesives such as Scotchbond Multi-Purposea or OptiBond FLb or two-step self-etching primer adhesives, such as Clearfil SEc, Unifil Bondd or AdheSEe, respectfully. PMID:26846037

Differences in the Microstructure and Fatigue Properties of Dentin Between Residents of North and South America

PubMed Central

Ivancik, J.; Naranjo, M.; Correa, S.; Ossa, A.; Tay, F.R.; Pashley, D.H.; Arola, D.

2014-01-01

Spatial variations in the microstructure of dentin contribute to its mechanical behavior. Objective The objective of this investigation was to compare the microstructure and fatigue behavior of dentin from donors of two different countries. Methods Caries-free third molars were obtained from dental practices in Colombia, South America and the US to assemble two age-matched samples. The microstructure of the coronal dentin was evaluated at three characteristic depths (i.e. deep, middle and superficial dentin) using scanning electron microscopy and image processing techniques. The mechanical behavior of dentin in these three regions was evaluated by the fatigue crack growth resistance. Cyclic crack growth was achieved in-plane with the dentin tubules and the fatigue crack growth behavior was characterized in terms of the stress intensity threshold and the Paris Law parameters. Results There was no difference in the tubule density between the dentin of patients from the two countries. However, there were significant differences (p≤0.05) in the tubule lumen diameters between the two groups in the deep and peripheral regions. In regards to the fatigue resistance, there was a significant increase (p≤0.05) in threshold stress intensity range, and a significant decrease in fatigue crack growth coefficient with increasing distance from the pulp in teeth from the US donors. In contrast, these properties were independent of location for the dentin of teeth from the Colombian donors. Conclusions The microstructure of dentin and its mechanical behavior appear to be a function of patient background, which may include environmental factors and/or ethnicity. PMID:24960115

The effect of propolis fluoride on caries dentine activity

NASA Astrophysics Data System (ADS)

Darwita, Risqa Rina; Soekanto, Sri Angky; Finisha, Andanali Rhukul; Wahyuni, Hardiati Nur; Andiani, Salsabila Ghina

2018-02-01

This research was conducted to analyze the effect of propolis fluoride on the occurrence of arrested caries dentine surface. The design of the study was a clinical trial experimental. The respondent were primary school students aged 6-8 years, from primary school in Kukusan, Depok, West Java, Indonesia. They were screened of dental examination and the total number of 296 children with an age range of 6-8 year old were included in the study. All students who had dentin caries were get dental treatment with propolis fluoride topical application in dentin caries surface. After one month, two months and four months all students who were got propolis fluoride topical application in dentin caries surface were controlled. All data were analyzed by Wilcoxon test. The total number of dentinal decay of 296 student was 1740 surfaces indicated to Flolis topical application. After one, two and three months of Flolis application, all arrested of dentinal decay was evaluated, the result of evaluation from the second month to the third month evaluation was found that the arrested dentinal caries surfaces were decreased significantly at 29.36% (p<0.01), while the evaluation of arrested dentinal caries surface from the first month to the third month was decreased significantly at 38.62% (p<0.001). Flolis was proven significantly to be able to arrest the activity of dental caries, and their ability to arrest dental caries was significantly different. Flolis was found to be effective in arresting dentinal caries surface until three months application, and should be repeated after 3 months of Flolis application.

Dentinal tubules revealed with X-ray tensor tomography.

PubMed

Jud, Christoph; Schaff, Florian; Zanette, Irene; Wolf, Johannes; Fehringer, Andreas; Pfeiffer, Franz

2016-09-01

Dentin is a mineralized material making up most of the tooth bulk. A system of microtubules, so called dentinal tubules, transverses it radially from the pulp chamber to the outside. This highly oriented structure leads to anisotropic mechanical properties directly connected to the tubules orientation and density: the ultimate tensile strength as well as the fracture toughness and the shear strength are largest perpendicular to dentinal tubules. Consequently, the fatigue strength depends on the direction of dentinal tubules, too. However, none of the existing techniques used to investigate teeth provide access to orientation and density of dentinal tubules for an entire specimen in a non-destructive way. In this paper, we measure a third molar human tooth both with conventional micro-CT and X-ray tensor tomography (XTT). While the achievable resolution in micro-CT is too low to directly resolve the dentinal tubules, we provide strong evidence that the direction and density of dentinal tubules can be indirectly measured by XTT, which exploits small-angle X-ray scattering to retrieve a 3D map of scattering tensors. We show that the mean directions of scattering structures correlate to the orientation of dentinal tubules and that the mean effective scattering strength provides an estimation of the relative density of dentinal tubules. Thus, this method could be applied to investigate the connection between tubule orientation and fatigue or tensile properties of teeth for a full sample without cutting one, non-representative peace of tooth out of the full sample. Copyright © 2016 The Academy of Dental Materials. All rights reserved.

Effect of surface protection on the permeability of eroded dentin

PubMed Central

Martins, Vivian Leite; da Costa Ramos, Rodrigo Vitoria; Pimenta Lima, Max José; Correia de Araújo, Roberto Paulo; Cavalcanti, Andrea Nóbrega

2018-01-01

Context: Eroded dentin might present the opening of dentinal tubules, increasing permeability, and consequently dentinal hypersensitivity. Aims: This study evaluated the permeability of dentin surfaces exposed to different levels of erosion and methods of surface protection. Materials and Methods: Dentine samples (3 mm × 3 mm × 1 mm) were prepared from bovine incisors (n = 90) and divided into three groups according to the method of controlling erosive challenge: Negative control, topical fluoride application, and glass ionomer sealant. Subsequently, they were randomly divided into three subgroups according to the exposure of simulated gastric acid solution (Demineralization – DES) (5% HCl, pH = 2.2), and remineralization (RE); negative control, 9 and 18 cycles DES-RE. The dentin permeability was measured by assessing the hydraulic conductance (μl/min.cmH2O.cm2). Statistical analysis was performed by two-way ANOVA and Tukey's test. Results and Conclusions: Greater permeability was observed after 18 erosive cycles, followed by exposure to 9 cycles and negative control (P < 0.0001). The application of glass ionomer sealant resulted in a major reduction of the hydraulic conductivity, regardless of the erosive challenge. Control groups and topical fluoride application showed similar results. In conclusion, the severity of erosive challenge contributed to the increase of dentin permeability. Besides, the glass ionomer sealant was the only protection agent that promoted significant effects in dentin permeability. PMID:29628641

The Effect of SnCl2/AmF Pretreatment on Short- and Long-Term Bond Strength to Eroded Dentin

PubMed Central

Zumstein, Katrin; Peutzfeldt, Anne; Lussi, Adrian

2018-01-01

This study investigated the effect of SnCl2/AmF pretreatment on short- and long-term bond strength of resin composite to eroded dentin mediated by two self-etch, MDP-containing adhesive systems. 184 dentin specimens were produced from extracted human molars. Half the specimens (n = 92) were artificially eroded, and half were left untreated. For both substrates, half the specimens were pretreated with SnCl2/AmF, and half were left untreated. The specimens were treated with Clearfil SE Bond or Scotchbond Universal prior to application of resin composite. Microtensile bond strength (μTBS) was measured after 24 h or 1 year. Failure mode was detected and EDX was performed. μTBS results were statistically analyzed (α = 0.05). μTBS was significantly influenced by the dentin substrate (eroded < noneroded dentin) and storage time (24 h > 1 year; p < 0.0001) but not by pretreatment with SnCl2/AmF or adhesive system. The predominant failure mode was adhesive failure at the dentin-adhesive interface. The content of Sn was generally below detection limit. Pretreatment with SnCl2/AmF did not influence short- and long-term bond strength to eroded dentin. Bond strength was reduced after storage for one year, was lower to eroded dentin than to noneroded dentin, and was similar for the two adhesive systems.

Preventive effect of a high fluoride toothpaste and arginine-carbonate toothpaste on dentinal tubules exposure followed by acid challenge: a dentine permeability evaluation

PubMed Central

2014-01-01

Background Considering the current high use of high fluoride toothpastes, the aim of the study was to quantify alterations in the root dentine permeability submitted to treatment with a high fluoride toothpaste and 8% arginine, calcium carbonate, sodium monofluorophosphate toothpaste as a preventive treatment for dentinal tubules exposure followed by acid challenge. Methods Thirty-third molars were sectioned below the cementoenamel. The root segments were connected to a hydraulic pressure apparatus to measure dentine permeability after the following sequential steps (n = 10 per group): I) Baseline; II) treatment with phosphoric acid for 30 s (maximum permeability); III) Toothbrushing (1 min) according to the experimental groups (G1- control; G2- 5000 ppm fluoride toothpaste; G3- 8% arginine-calcium carbonate toothpaste); IV) acid challenge for 5 min (orange juice). The data were converted into percentage, considering stage II as 100%. Results The results have shown a statistically significant decreasing on dentine permeability after treatment with toothpaste (Friedman test and Dunn’s post hoc test). Comparison among groups demonstrated a high increasing on dentine permeability when acid challenge was performed after toothbrushing with distilled water (control group) (Kruskal-Wallis and Dunn’s post hoc test). Conclusion The toothpaste treatment may provide sufficient resistance on dentine surface, preventing dentinal tubules exposure after acid challenge. PMID:24958423

Hardness and elasticity of caries-affected and sound primary tooth dentin bonded with 4-META one-step self-etch adhesives

PubMed Central

Hosoya, Yumiko; Tay, Franklin R.; Miyakoshi, Shoichi; Pashley, David H.

2013-01-01

Purpose This study evaluated the quality of the interface of sound and carious primary tooth dentin bonded with two 4-META one-step self-etch adhesives. Methods Twelve sound and twelve carious primary molars were bonded with AQ Bond Plus (AQBP; Sun Medical) or Hybrid Bond (HB; Sun Medical) and restored with Clearfil Protect Liner F (Kuraray Medical Inc.). After 24 hours of water immersion, the teeth were sectioned and polished. Resin-dentin interfaces were measured with a nano-indentation tester and hardness and Young’s modulus were calculated. Data were analyzed using one-way or two-ways ANOVA and Fisher’s PLSD test with α=0.05. Resin-dentin interfaces were also observed with SEM and TEM. Ammoniacal silver nitrate was used as a tracer for TEM observation. Results Hardness and Young’s modulus of the interfacial dentin were significantly lower than the underlying intact dentin except for the carious-AQBP group. However, there was no significant difference of hardness and Young's moduli of the interfacial dentin among all groups. TEM revealed extensive interfacial nanoleakage in sound dentin bonded with either AQBP or HB. For the carious teeth, nanoleakage was absent in the hybrid layers bonded with the two adhesives. However, extensive silver deposits were identified from the subsurface, porous caries-affected dentin. PMID:18795517

Differences between micro-hardness affected dentin after mechanical or chemo-mechanical infected dentin disposal (laboratory experiment)

NASA Astrophysics Data System (ADS)

Ihsani, V.; Nursasongko, B.; Djauharie, N.

2017-08-01

The concept of conserving healthy tooth structures during cavity preparation has gained popularity with chemo-mechanical caries removal. This study compared three methods of caries removal using: a chemo-mechanical caries removal papain gel; Papacarie® (these contain natural ingredients, mainly papain enzyme); and mechanical preparation with a bur rotary instrument. The purpose of this study was to compare affected dentin micro-hardness after removal of infected dentin with mechanical and chemo-mechanical techniques. Twenty-seven permanent molar teeth were randomly divided into three groups receiving removal of infected dentin. These were: Group 1: chemo-mechanical technique using papain gel; Group 2: chemo-mechanical technique using Papacarie® Group 3: mechanical technique using a bur rotary instrument. Each group was tested using Knoop Micro-hardness tester, and the data were submitted to one way ANOVA and Post-hoc Tukey test. There is a significant difference between Groups 1 and 3, and Groups 2 and 3, p = 0.000. However, there is no significant difference between Groups 1 and 2, p = 1.000. Affected dentin micro-hardness after removal of infected dentin with a bur rotary tool is higher than after use of the papain gel or Papacarie®. Affected dentin micro-hardness after removal of infected dentin with Papacarie® and papain gel give almost the same result.

Effect of etching on bonding of a self-etch adhesive to dentine affected by amelogenesis imperfecta.

PubMed

Epasinghe, Don Jeevanie; Yiu, Cynthia Kar Yung

2018-02-01

Dentine affected by amelogenesis imperfecta (AI) is histologically altered due to loss of hypoplastic enamel and becomes hypermineralized. In the present study, we examined the effect of additional acid etching on microtensile bond strength of a self-etch adhesive to AI-affected dentine. Flat coronal dentine obtained from extracted AI-affected and non-carious permanent molars were allocated to two groups: (a) Clearfil SE Bond (control); and (b) Clearfil SE Bond and additional etching with 34% phosphoric acid for 15 seconds. The bonded teeth were sectioned into .8-mm 2 beams for microtensile bond strength testing, and stressed to failure under tension. The bond strength data were analyzed using two-way analysis of variance (dentine type and etching step) and Student-Newman-Keuls multiple comparison test (P<.05). Representative fractured beams from each group were examined under scanning electron microscopy. Both factors, dentine substrate (P<.001) and etching step (P<.05), and their interactions (P<.001), were statistically significant. Additional etching had an adverse effect on the bond strength of Clearfil SE Bond to normal dentine (P<.005), and no significant improvement was found for AI-affected dentine (P=.479). Additional acid etching does not improve the bond strength of a self-etch adhesive to AI-affected dentine. © 2017 John Wiley & Sons Australia, Ltd.

Penetration of sub-micron particles into dentinal tubules using ultrasonic cavitation.

PubMed

Vyas, N; Sammons, R L; Pikramenou, Z; Palin, W M; Dehghani, H; Walmsley, A D

2017-01-01

Functionalised silica sub-micron particles are being investigated as a method of delivering antimicrobials and remineralisation agents into dentinal tubules. However, their methods of application are not optimised, resulting in shallow penetration and aggregation. The aim of this study is to investigate the impact of cavitation occurring around ultrasonic scalers for enhancing particle penetration into dentinal tubules. Dentine slices were prepared from premolar teeth. Silica sub-micron particles were prepared in water or acetone. Cavitation from an ultrasonic scaler (Satelec P5 Newtron, Acteon, France) was applied to dentine slices immersed inside the sub-micron particle solutions. Samples were imaged with scanning electron microscopy (SEM) to assess tubule occlusion and particle penetration. Qualitative observations of SEM images showed some tubule occlusion. The particles could penetrate inside the tubules up to 60μm when there was no cavitation and up to ∼180μm when there was cavitation. The cavitation bubbles produced from an ultrasonic scaler may be used to deliver sub-micron particles into dentine. This method has the potential to deliver such particles deeper into the dentinal tubules. Cavitation from a clinical ultrasonic scaler may enhance penetration of sub-micron particles into dentinal tubules. This can aid in the development of novel methods for delivering therapeutic clinical materials for hypersensitivity relief and treatment of dentinal caries. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimizing dentin bond durability: control of collagen degradation by matrix metalloproteinases and cysteine cathepsins

PubMed Central

Tjäderhane, Leo; Nascimento, Fabio D.; Breschi, Lorenzo; Mazzoni, Annalisa; Tersariol, Ivarne L.S.; Geraldeli, Saulo; Tezvergil-Mutluay, Arzu; Carrilho, Marcela R.; Carvalho, Ricardo M.; Tay, Franklin R.; Pashley, David H.

2012-01-01

Objectives Contemporary adhesives lose their bond strength to dentin regardless of the bonding system used. This loss relates to the hydrolysis of collagen matrix of the hybrid layers. The preservation of the collagen matrix integrity is a key issue in the attempts to improve the dentin bonding durability. Methods Dentin contains collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins, which are responsible for the hydrolytic degradation of collagen matrix in the bonded interface. Results The identities, roles and function of collagenolytic enzymes in mineralized dentin has been gathered only within last 15 years, but they have already been demonstrated to have an important role in dental hard tissue pathologies, including the degradation of the hybrid layer. Identifying responsible enzymes facilitates the development of new, more efficient methods to improve the stability of dentin-adhesive bond and durability of bond strength. Significance Understanding the nature and role of proteolytic degradation of dentin-adhesive interfaces has improved immensely and has practically grown to a scientific field of its own within only 10 years, holding excellent promise that stable resin-dentin bonds will be routinely available in a daily clinical setting already in a near future. PMID:22901826

Dietary adaptions in the ultrastructure of dinosaur dentine.

PubMed

Brink, Kirstin S; Chen, Yu-Cheng; Wu, Ya-Na; Liu, Wei-Min; Shieh, Dar-Bin; Huang, Timothy D; Sun, Chi-Kuang; Reisz, Robert R

2016-12-01

Teeth are key to understanding the feeding ecology of both extant and extinct vertebrates. Recent studies have highlighted the previously unrecognized complexity of dinosaur dentitions and how specific tooth tissues and tooth shapes differ between taxa with different diets. However, it is unknown how the ultrastructure of these tooth tissues contributes to the differences in feeding style between taxa. In this study, we use third harmonic generation microscopy and scanning electron microscopy to examine the ultrastructure of the dentine in herbivorous and carnivorous dinosaurs to understand how the structure of this tissue contributes to the overall utility of the tooth. Morphometric analyses of dentinal tubule diameter, density and branching rates reveal a strong signal for dietary preferences, with herbivorous saurischian and ornithischian dinosaurs consistently having higher dentinal tubule density than their carnivorous relatives. We hypothesize that this relates to the hardness of the dentine, where herbivorous taxa have dentine that is more resistant to breakage and wear at the dentine-enamel junction than carnivorous taxa. This study advocates the detailed study of dentine and the use of advanced microscopy techniques to understand the evolution of dentition and feeding ecology in extinct vertebrates. © 2016 The Author(s).

An experiment on the attrition of acid demineralized dentine in vitro.

PubMed

Li, H; Liu, M C; Deng, M; Moazzez, R; Bartlett, D W

2011-03-01

A laboratory investigation was designed to test the hypothesis that acids increase the rate of wear caused by attrition on dentine. Dentine sections from 10 teeth were polished, cleaned in an ultrasonic bath and divided into 8 equally sized areas. The occlusal tip of a tooth, placed vertically in a wear machine and loaded at 150 N, was moved against each dentine section for 5000 return strokes with artificial saliva acting as a lubricant. Each dentine section was divided into 8 sections and half randomly immersed in a 1% citric acid solution (pH 2.3) for 20 minutes. The wear regime produced 8 wear scars in total per dentine sample. The volume of each wear scar was measured using a contacting digitizing profilometer. A total of 80 wear scars were produced with 40 treated with acid and 40 acting as controls. The mean for wear volume of the dentine scars with acid was 4.84 μm(3) (1.38) and for the non-acid surface 2.95 μm(3) (0.86). This difference was statistically significant (p < 0.05). These results support the hypothesis that acids increase the rate of wear caused by attrition on dentine. © 2011 Australian Dental Association.

The effects of dentin and intaglio indirect ceramic optimized polymer restoration surface treatment on the shear bond strength of resin cement

NASA Astrophysics Data System (ADS)

Puspitarini, A.; Suprastiwi, E.; Usman, M.

2017-08-01

Ceramic optimized polymer (ceromer) bonds to the tooth substrate through resin cements. The bond strength between dentin, resin cement, and ceromer depends on the applied surface treatment. To analyze the effects of dentin and intaglio ceromer surface treatment on the shear bond strength self-adhesive resin cement. Forty-five dentin premolar and ceromer specimens were bonded with resin cement and divided into three groups as follows: in group 1, no treatment was applied; in group 2, dentin surface treatment was carried out with acid etching and a bonding agent; and in group 3, dentin surface treatment was carried out with acid etching, a bonding agent, and intaglio ceromer surface treatment with etching and silane. All specimens were incubated at 37 °C for 24 hours, and the shear bond strength was measured using a universal testing machine. Group 3 showed the highest shear bond strength, followed by group 2. The surface treatment of dentin and intaglio ceromer showed significantly improved shear bond strength in the group comparison. Dentin and intaglio ceromer surface treatment can improved the shear bond strength self-adhesive resin cement.

Simulation of bone resorption-repair coupling in vitro.

PubMed

Jones, S J; Gray, C; Boyde, A

1994-10-01

In the normal adult human skeleton, new bone formation by osteoblasts restores the contours of bone surfaces following osteoclastic bone resorption, but the evidence for resorption-repair coupling remains circumstantial. To investigate whether sites of prior resorption, more than the surrounding unresorbed surface, attract osteoblasts or stimulate them to proliferate or make new matrix, we developed a simple in vitro system in which resorption-repair coupling occurs. Resorption pits were produced in mammalian dentine or bone slabs by culturing chick bone-derived cells on them for 2-3 days. The chick cells were swept off and the substrata reseeded with rat calvarial osteoblastic cells, which make bone nodules in vitro, for periods of up to 8 weeks. Cell positions and new bone formation were investigated by ordinary light microscopy, fluorescence and reflection confocal laser microscopy, and SEM, in stained and unstained samples. There was no evidence that the osteoblasts were especially attracted to, or influenced by, the sites of resorption in dentine or bone before cell confluence was reached. Bone formation was identified by light microscopy by the accumulation of matrix, staining with alizarin and calcein and by von Kossa's method, and confirmed by scanning electron microscopy (SEM) by using backscattered electron (BSE) and transmitted electron imaging of unembedded samples and BSE imaging of micro-milled embedded material. These new bone patches were located initially in the resorption pits. The model in vitro system may throw new light on the factors that control resorption-repair coupling in the mineralised tissues in vivo.

Dentin barrier test with transfected bovine pulp-derived cells.

PubMed

Schmalz, G; Schuster, U; Thonemann, B; Barth, M; Esterbauer, S

2001-02-01

Growth kinetics of SV40 large T-antigen-transfected bovine pulp-derived cells on dentin were investigated. These cells were used in a dentin barrier test device, and the system was evaluated by testing a set of dental filling materials. Cells (120 cells/mm2) were seeded on dentin slices and incubated for up to 21 days. Cell proliferation was recorded using MTT assay. For cytotoxicity tests 3500 cells/mm2 were seeded on dentin discs, which were then incorporated into the dentin barrier test device. After 72 h preincubation test materials were applied. After a 24 h exposure with or without perfusion of the pulpal part of the test device, cell survival was evaluated using MTT assay. The cells revealed similar growth kinetics on dentin slices and on tissue culture plates. In cytotoxicity tests the cells were more sensitive toward the test materials than previously used three-dimensional cultures of human foreskin fibroblasts and as anticipated from clinical experience. Further improvement is expected by using three-dimensional cultures of pulp-derived cells.

Crack propagation in teeth: a comparison of perimortem and postmortem behavior of dental materials and cracks.

PubMed

Hughes, Cris E; White, Crystal A

2009-03-01

This study presents a new method for understanding postmortem heat-induced crack propagation patterns in teeth. The results demonstrate that patterns of postmortem heat-induced crack propagation differ from perimortem and antemortem trauma-induced crack propagation patterns. Dental material of the postmortem tooth undergoes dehydration leading to a shrinking and more brittle dentin material and a weaker dentin-enamel junction. Dentin intertubule tensile stresses are amplified by the presence of the pulp cavity, and initiates crack propagation from the internal dentin, through the dentin-enamel junction and lastly the enamel. In contrast, in vivo perimortem and antemortem trauma-induced crack propagation initiates cracking from the external surface of the enamel toward the dentin-enamel junction where the majority of the energy of the crack is dissipated, eliminating the crack's progress into the dentin. These unique patterns of crack propagation can be used to differentiate postmortem taphonomy-induced damage from antemortem and perimortem trauma in teeth.

Is diagnosing exposed dentine a suitable tool for grading erosive loss?

PubMed Central

Ganss, Carolina

2008-01-01

Quantifying tooth wear in general and erosion in particular mostly is made by distinguishing between lesions restricted to enamel and lesions reaching the underlying dentine. Various scores for grading have been used, but in all systems, higher scores are given in cases of exposed dentine, thus, indicating a more severe stage of the condition. Clinical diagnosis of exposed dentine is made by assessing changes in colour or optical properties of the hard tissues. This paper aims to review the literature and discuss critically problems arising form this approach. It appears that classifying the severity of erosion by the area or depth of exposed dentine is difficult and poorly reproducible, and taking into account the variation of enamel thickness, the amount of tissue lost often is not related simply to the area of exposed dentine. There has still been very little longitudinal investigation of the significance of exposed dentine as a prognostic indicator. Further work and discussion is needed to reevaluate the explanative power of current grading procedures. PMID:18228063

Technique sensitivity in bonding to enamel and dentin.

PubMed

Powers, John M; Farah, John W

2010-09-01

Bonding to enamel and dentin has been among the most significant advancements in dentistry in the last five decades; extensive research and product development have resulted in more adhesive options. However, bonding to enamel and dentin still proves to be challenging, and selecting the correct product for a clinical application can be confusing. An incorrect choice can lead to insufficient bond strength. Day-to-day clinical factors, such as the presence of enamel, superficial dentin, or carious dentin, as well as contamination by saliva, blood, or bleaching agents, can cause bonding agents to be technique sensitive-they may fail prematurely if steps are not followed meticulously. This article attempts to simplify the selection process for enamel and dentinal bonding and summarize clinically relevant bonding information that will help produce consistently successful results.

[Preventive dentistry 3. Prevalence, aetiology and diagnosis of dentine (hyper)sensitivity].

PubMed

van der Weijden, F N; van Loveren, C; Slot, D E; van der Weijden, G A

2017-02-01

Many people sometimes experience pain when they inhale breath across the cingula, or sensitivity and/or pain when they eat ice cream, for example. In some cases, however, this can become seriously unpleasant. In those cases, one can speak of dentine hypersensitivity. In Europe, an average of 27% of the population suffers from this. Dentine hypersensitivity is characterised by a short, sharp pain reaction after a warm or cold sensation. The external sensation causes an accelerated or converse flow of fluid in the dentinal tubules that excites the extremities of the nerve cells, which results in the sensation pain. For the external sensation, it is necessary that the cingula are exposed and the dentinal tubules are open. Dentine hypersensitivity is diagnosed after other possibilities have been eliminated.

Dentin matrix degradation by host matrix metalloproteinases: inhibition and clinical perspectives toward regeneration

PubMed Central

Chaussain, Catherine; Boukpessi, Tchilalo; Khaddam, Mayssam; Tjaderhane, Leo; George, Anne; Menashi, Suzanne

2013-01-01

Bacterial enzymes have long been considered solely accountable for the degradation of the dentin matrix during the carious process. However, the emerging literature suggests that host-derived enzymes, and in particular the matrix metalloproteinases (MMPs) contained in dentin and saliva can play a major role in this process by their ability to degrade the dentin matrix from within. These findings are important since they open new therapeutic options for caries prevention and treatment. The possibility of using MMP inhibitors to interfere with dentin caries progression is discussed. Furthermore, the potential release of bioactive peptides by the enzymatic cleavage of dentin matrix proteins by MMPs during the carious process is discussed. These peptides, once identified, may constitute promising therapeutical tools for tooth and bone regeneration. PMID:24198787

[Effect of phenolic resin fluid on the dentin resistance].

PubMed

Xu, J

1990-11-01

SEM observation was made in the experiment to analyze the ultrastructure of resinified dentin. Phenolic resin fluid permeates in to the dentinal-tubule and set in it. The permeability of this agent was also able to permeate into intercellular substance and changed the appearance of inter-weaved fibril to the condition of agent had set. According to the Fracture Mechanics, it was not beneficial to resist the fracture progress if the microspace had been fulfilled by the agent. The tensile stress of resinified dentin was 387 kg/cm2, which was 30 kg/cm2 lower than that of unresinified-dentin.

Intercellular signal communication among odontoblasts and trigeminal ganglion neurons via glutamate.

PubMed

Nishiyama, A; Sato, M; Kimura, M; Katakura, A; Tazaki, M; Shibukawa, Y

2016-11-01

Various stimuli to the exposed surface of dentin induce changes in the hydrodynamic force inside the dentinal tubules resulting in dentinal pain. Recent evidences indicate that mechano-sensor channels, such as the transient receptor potential channels, in odontoblasts receive these hydrodynamic forces and trigger the release of ATP to the pulpal neurons, to generate dentinal pain. A recent study, however, has shown that odontoblasts also express glutamate receptors (GluRs). This implies that cells in the dental pulp tissue have the ability to release glutamate, which acts as a functional intercellular mediator to establish inter-odontoblast and odontoblast-trigeminal ganglion (TG) neuron signal communication. To investigate the intercellular signal communication, we applied mechanical stimulation to odontoblasts and measured the intracellular free Ca 2+ concentration ([Ca 2+ ] i ). During mechanical stimulation in the presence of extracellular Ca 2+ , we observed a transient [Ca 2+ ] i increase not only in single stimulated odontoblasts, but also in adjacent odontoblasts. We could not observe these responses in the absence of extracellular Ca 2+ . [Ca 2+ ] i increases in the neighboring odontoblasts during mechanical stimulation of single odontoblasts were inhibited by antagonists of metabotropic glutamate receptors (mGluRs) as well as glutamate-permeable anion channels. In the odontoblast-TG neuron coculture, we observed an increase in [Ca 2+ ] i in the stimulated odontoblasts and TG neurons, in response to direct mechanical stimulation of single odontoblasts. These [Ca 2+ ] i increases in the neighboring TG neurons were inhibited by antagonists for mGluRs. The [Ca 2+ ] i increases in the stimulated odontoblasts were also inhibited by mGluRs antagonists. We further confirmed that the odontoblasts express group I, II, and III mGluRs. However, we could not record any currents evoked from odontoblasts near the mechanically stimulated odontoblast, with or without extracellular Mg 2+ , indicating that N-methyl-d-aspartic acid receptor does not contribute to inter-odontoblast signal communication. The results suggest that a mechanically stimulated odontoblast is capable of releasing glutamate into the extracellular space via glutamate-permeable anion channels. The released glutamate activates mGluRs on the odontoblasts in an autocrine/paracrine manner, forming an inter-odontoblasts communication, which drives dentin formation via odontoblast-odontoblast signal communication. Glutamate and mGluRs also mediate neurotransmission between the odontoblasts and neurons in the dental pulp to modulate sensory signal transmission for dentinal sensitivity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantitative analysis of aqueous phase composition of model dentin adhesives experiencing phase separation

PubMed Central

Ye, Qiang; Park, Jonggu; Parthasarathy, Ranganathan; Pamatmat, Francis; Misra, Anil; Laurence, Jennifer S.; Marangos, Orestes; Spencer, Paulette

2013-01-01

There have been reports of the sensitivity of our current dentin adhesives to excess moisture, for example, water-blisters in adhesives placed on over-wet surfaces, and phase separation with concomitant limited infiltration of the critical dimethacrylate component into the demineralized dentin matrix. To determine quantitatively the hydrophobic/hydrophilic components in the aqueous phase when exposed to over-wet environments, model adhesives were mixed with 16, 33, and 50 wt % water to yield well-separated phases. Based upon high-performance liquid chromatography coupled with photodiode array detection, it was found that the amounts of hydrophobic BisGMA and hydrophobic initiators are less than 0.1 wt % in the aqueous phase. The amount of these compounds decreased with an increase in the initial water content. The major components of the aqueous phase were hydroxyethyl methacrylate (HEMA) and water, and the HEMA content ranged from 18.3 to 14.7 wt %. Different BisGMA homologues and the relative content of these homologues in the aqueous phase have been identified; however, the amount of crosslinkable BisGMA was minimal and, thus, could not help in the formation of a crosslinked polymer network in the aqueous phase. Without the protection afforded by a strong crosslinked network, the poorly photoreactive compounds of this aqueous phase could be leached easily. These results suggest that adhesive formulations should be designed to include hydrophilic multimethacrylate monomers and water compatible initiators. PMID:22331596

In Vitro Adhesion of Streptococcus sanguinis to Dentine Root Surface After Treatment with Er:Yag Laser, Ultrasonic System, or Manual Curette

PubMed Central

Martins, Fernanda L.; Giorgetti, Ana Paula O.; de Freitas, Patrícia M.; Duarte, Poliana M.

2009-01-01

Abstract Objective: The purpose of this in vitro study was to evaluate the dentine root surface roughness and the adherence of Streptococcus sanguinis (ATCC 10556) after treatment with an ultrasonic system, Er:YAG laser, or manual curette. Background Data: Bacterial adhesion and formation of dental biofilm after scaling and root planing may be a challenge to the long-term stability of periodontal therapy. Materials and Methods: Forty flattened bovine roots were randomly assigned to one of the following groups: ultrasonic system (n = 10); Er:YAG laser (n = 10); manual curette (n = 10); or control untreated roots (n = 10). The mean surface roughness (Ra, μm) of the specimens before and after exposure to each treatment was determined using a surface profilometer. In addition, S. sanguinis was grown on the treated and untreated specimens and the amounts of retained bacteria on the surfaces were measured by culture method. Results: All treatments increased the Ra; however, the roughest surface was produced by the curettes. In addition, the specimens treated with curettes showed the highest S. sanguinis adhesion. There was a significant positive correlation between roughness values and bacterial cells counts. Conclusion: S. sanguinis adhesion was the highest on the curette-treated dentine root surfaces, which also presented the greatest surface roughness. PMID:19712018

Optimization of the etch-and-rinse technique: New perspectives to improve resin-dentin bonding and hybrid layer integrity by reducing residual water using dimethyl sulfoxide pretreatments.

PubMed

Stape, Thiago Henrique Scarabello; Tjäderhane, Leo; Abuna, Gabriel; Sinhoreti, Mário Alexandre Coelho; Martins, Luís Roberto Marcondes; Tezvergil-Mutluay, Arzu

2018-04-13

To determine whether bonding effectiveness and hybrid layer integrity on acid-etched dehydrated dentin would be comparable to the conventional wet-bonding technique through new dentin biomodification approaches using dimethyl sulfoxide (DMSO). Etched dentin surfaces from extracted sound molars were randomly bonded in wet or dry conditions (30s air drying) with DMSO/ethanol or DMSO/H 2 O as pretreatments using a simplified (Scotchbond Universal Adhesive, 3M ESPE: SU) and a multi-step (Adper Scotchbond Multi-Purpose, 3M ESPE: SBMP) etch-and-rinse adhesives. Untreated dentin surfaces served as control. Bonded teeth (n=8) were stored in distilled water for 24h and sectioned into resin-dentin beams (0.8mm 2 ) for microtensile bond strength test and quantitative interfacial nanoleakage analysis (n=8) under SEM. Additional teeth (n=2) were prepared for micropermeability assessment by CFLSM under simulated pulpar pressure (20cm H 2 O) using 5mM fluorescein as a tracer. Microtensile data was analyzed by 3-way ANOVA followed by Tukey Test and nanoleakage by Kruskal-Wallis and Dunn-Bonferroni multiple comparison test (α=0.05). While dry-bonding of SBMP produced significantly lower bond strengths than wet-bonding (p<0.05), DMSO/H 2 O and DMSO/ethanol produced significantly higher bond strengths for SBMP irrespective of dentin condition (p<0.05). SU presented significantly higher nanoleakage levels (p<0.05) and micropermeability than SBMP. Improvement in hybrid layer integrity occurred for SBMP and SU for both pretreatments, albeit most pronouncedly for DMSO/ethanol regardless of dentin moisture. DMSO pretreatments may be used as a new suitable strategy to improve bonding of water-based adhesives to demineralized air-dried dentin beyond conventional wet-bonding. Less porous resin-dentin interfaces with higher bond strengths on air-dried etched dentin were achieved; nonetheless, overall efficiency varied according to DMSO's co-solvent and adhesive type. DMSO pretreatments permit etched dentin to be air-dried before hybridization facilitating residual water removal and thus improving bonding effectiveness. This challenges the current paradigm of wet-bonding requirement for the etch-and-rinse approach creating new possibilities to enhance the clinical longevity of resin-dentin interfaces. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

Prostate Cancer Progression and Serum SIBLING (Small Integrin Binding N-linked Glycoprotein) Levels

DTIC Science & Technology

2006-10-01

members include bone sialoprotein (BSP), osteopontin (OPN), dentin matrix protein-1 (DMP1), dentin sialophosphoprotein (DSPP) and matrix extracellular...quantitatively determining the levels of bone sialoprotein (BSP), osteopontin (OPN), and dentin sialophosphoprotein (DSPP). In addition we have a...panels e and f). 6 Figure 1. Serum levels of SIBLINGs in prostate cancer sera. Serum levels of (a) bone sialoprotein (BSP), (c) dentin

A scanning electron microscopic evaluation of in vitro dentinal tubules penetration by selected anaerobic bacteria.

PubMed

Siqueira, J F; De Uzeda, M; Fonseca, M E

1996-06-01

In vitro root canal dentinal tubule invasion by selected anaerobic bacteria commonly isolated from endodontic infections was evaluated. Dentinal cylinders obtained from bovine incisors were inoculated with bacteria, and microbial penetration into tubules was demonstrated by scanning electron microscopy. The results indicated that all bacterial strains tested were able to penetrate into dentinal tubules, but to different extents.

A safety study in vitro for the effects of an in-office bleaching system on the integrity of enamel and dentine.

PubMed

Sulieman, M; Addy, M; Macdonald, E; Rees, J S

2004-09-01

The aim of this study was to investigate safety concerns with bleaching procedures by studying the effects of a high concentration hydrogen peroxide (HP) in-surgery bleaching product on enamel and dentine. Flat enamel and dentine samples embedded in epoxy resin were prepared from human third molar teeth. Erosion of enamel: groups of enamel samples were treated with 35% HP then citric acid (CA) or brushing with toothpaste or CA alone and water alone. Enamel Loss was measured using a profilometer. Abrasion/erosion of dentine: groups of dentine specimens were treated as follows: Group 1--brushed with water for 30 min. Group 2--brushed with 35% HP for 30 min. Group 3--power bleached for 30 min and then Group 4--brushed with toothpaste for 1 minute. Group 5--water soaked for 30 min followed by brushing with toothpaste for 1 min. Group 6--orange juice soaked for 30 min followed by brushing with toothpaste for 1 min. Treatment effects were measured using a profilometer. Hardness tests: enamel and dentine specimens were hardness tested using a Wallace indenter prior to and post bleaching. Scanning Electron Microscopy: enamel and dentine specimens were taped and the exposed tissue treated with 35% HP and then studied under scanning electronmicroscopy (SEM). Enamel erosion: bleaching enamel samples had no measurable effect on enamel. Pre-bleaching had no significant effect on subsequent CA erosion or brushing. Abrasion/erosion of dentine: no significant differences were found between treatments 1-5 with little change from baseline detected. Orange juice (Group 6) produced considerable and significantly more erosion than other treatments. Hardness tests: there were no significant changes in hardness values for enamel and dentine. SEM: there was no evidence of any topographical changes to either enamel or dentine. Using one of the highest concentrations of HP for tooth bleaching procedures and maximum likely peroxide exposure, there was no evidence of deleterious effects on enamel or dentine. It must be assumed that studies which reported adverse effects on enamel and or dentine of bleaches reflect not the bleach itself but the pH of the formulation used.

MMP20 Promotes a Smooth Enamel Surface, a Strong DEJ, and a Decussating Enamel Rod Pattern

PubMed Central

Bartlett, John D.; Skobe, Ziedonis; Nanci, Antonio; Smith, Charles E.

2012-01-01

Mutations of the Matrix metalloproteinase-20 (MMP20, enamelysin) gene cause autosomal recessive amelogenesis imperfecta and Mmp20 ablated mice also have malformed dental enamel. Here we show that Mmp20 null mouse secretory stage ameloblasts maintained a columnar shape and were present as a single layer of cells. However, the null maturation stage ameloblasts covered extraneous nodules of ectopic calcified material formed at the enamel surface. Remarkably, nodule formation occurs in null mouse enamel when MMP20 is normally no longer expressed. The malformed enamel in Mmp20 null teeth was loosely attached to the dentin and the entire enamel layer tended to separate from the dentin indicative of a faulty DEJ. The enamel rod pattern was also altered in Mmp20 null mice. Each enamel rod is formed by a single ameloblast and is a mineralized record of the migration path of the ameloblast that formed it. The Mmp20 null mouse enamel rods were grossly malformed or were absent indicating that the ameloblasts do not migrate properly when backing away from the DEJ. Thus, MMP20 is required for ameloblast cell movement necessary to form the decussating enamel rod patterns, for the prevention of ectopic mineral formation, and to maintain a functional DEJ. PMID:22243247

Regeneration of dental pulp by stem cells.

PubMed

Nakashima, M; Iohara, K

2011-07-01

Angiogenesis/vasculogenesis and neurogenesis are essential for pulp regeneration. Two subfractions of side-population (SP) cells, CD31(-)/CD146(-) SP cells and CD105(+) cells with angiogenic and neurogenic potential, were isolated by flow cytometry from canine dental pulp. In an experimental model of mouse hindlimb ischemia, transplantation of these cell populations resulted in an increase in blood flow, including high-density capillary formation. In a model of rat cerebral ischemia, stem cell transplantations enhanced neuronal regeneration and recovery from motor disability. Autologous transplantation of the CD31(-)/CD146(-) SP cells into an in vivo model of amputated pulp resulted in complete regeneration of pulp tissue with vascular and neuronal processes within 14 days. The transplanted cells expressed pro-angiogenic factors, implying trophic action on endothelial cells. Autologous transplantation of CD31(-)/CD146(-) SP cells or CD105(+) cells with stromal-cell-derived factor-1 (SDF-1) into root canals after whole pulp removal of mature teeth resulted in complete regeneration of pulp replete with nerves and vasculature by day 14, followed by dentin formation along the dentinal wall by day 35. Therefore, the potential utility of fractionated SP cells and CD105(+) cells in angiogenesis and neurogenesis was demonstrated by treatment of limb and cerebral ischemia following pulpotomy and pulpectomy.

In vitro dentin barrier cytotoxicity testing of some dental restorative materials.

PubMed

Jiang, R D; Lin, H; Zheng, G; Zhang, X M; Du, Q; Yang, M

2017-03-01

To investigate the cytotoxicity of four dental restorative materials in three-dimensional (3D) L929 cell cultures using a dentin barrier test. The cytotoxicities of light-cured glass ionomer cement (Vitrebond), total-etching adhesive (GLUMA Bond5), and two self-etching adhesives (GLUMA Self Etch and Single Bond Universal) were evaluated. The permeabilities of human dentin disks with thicknesses of 300, 500, and 1000μm were standardized using a hydraulic device. Test materials and controls were applied to the occlusal side of human dentin disks. The 3D-cell scaffolds were placed beneath the dentin disks. After a 24-h contact with the dentin barrier test device, cell viabilities were measured by performing MTT assays. Statistical analysis was performed using the Mann-Whitney U test. The mean (SD) permeabilities of the 300-μm, 500-μm, and 1000-μm dentin disks were 0.626 (0.214), 0.219 (0.0387) and 0.089 (0.028) μlmin -1 cm -2 cm H 2 O -1 . Vitrebond was severely cytotoxic, reducing the cell viability to 10% (300-μm disk), 17% (500μm), and 18% (1000μm). GLUMA Bond5 reduced the cell viability to 40% (300μm), 83% (500μm), and 86% (1000μm), showing moderate cytotoxicity (300-μm) and non-cytotoxicity (500-μm and 1000-μm). Single Bond Universal and GLUMA Self Etch did not significantly reduce cell viability, regardless of the dentin thicknesses, which characterized them as non-cytotoxic. Cytotoxicity varied with the materials tested and the thicknesses of the dentin disks. The tested cytotoxicity of materials applied on 300-, 500-, and 1000-μm dentin disks indicates that the clinical use of the test materials (excepting self-etching adhesives) in deep cavities poses a potential risk of damage to the pulp tissues to an extent, depending on the thickness of the remaining dentin. Copyright © 2017 Elsevier Ltd. All rights reserved.

Resin-dentin bonds to EDTA-treated vs. acid-etched dentin using ethanol wet-bonding. Part II: Effects of mechanical cycling load on microtensile bond strengths.

PubMed

Sauro, Salvatore; Toledano, Manuel; Aguilera, Fatima Sánchez; Mannocci, Francesco; Pashley, David H; Tay, Franklin R; Watson, Timothy F; Osorio, Raquel

2011-06-01

To compare microtensile bond strengths (MTBS) subsequent to load cycling of resin bonded acid-etched or EDTA-treated dentin using a modified ethanol wet-bonding technique. Flat dentin surfaces were obtained from extracted human molars and conditioned using 37% H(3)PO(4) (PA) (15s) or 0.1M EDTA (60s). Five experimental adhesives and one commercial bonding agent were applied to the dentin and light-cured. Solvated experimental resins (50% ethanol/50% comonomers) were used as primers and their respective neat resins were used as the adhesives. The resin-bonded teeth were stored in distilled water (24h) or submitted to 5000 loading cycles of 90N. The bonded teeth were then sectioned in beams for MTBS. Modes of failure were examined by scanning electron microscopy. The most hydrophobic resin 1 gave the lowest bond strength values to both acid and EDTA-treated dentin. The hydrophobic resin 2 applied to EDTA-treated dentin showed lower bond strengths after cycling load but this did not occur when it was bonded to PA-etched dentin. Resins 3 and 4, which contained hydrophilic monomers, gave higher bond strengths to both EDTA-treated or acid-etched dentin and showed no significant difference after load cycling. The most hydrophilic resin 5 showed no significant difference in bond strengths after cycling loading when bonded to EDTA or phosphoric acid treated dentin but exhibited low bond strengths. The presence of different functional monomers influences the MTBS of the adhesive systems when submitted to cyclic loads. Adhesives containing hydrophilic comonomers are not affected by cycling load challenge especially when applied on EDTA-treated dentin followed by ethanol wet bonding. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The effects of ethanol on the size-exclusion characteristics of type I dentin collagen to adhesive resin monomers.

PubMed

Chiba, A; Zhou, J; Nakajima, M; Tan, J; Tagami, J; Scheffel, D L S; Hebling, J; Agee, K A; Breschi, L; Grégoire, G; Jang, S S; Tay, F R; Pashley, D H

2016-03-01

During dentin bonding with etch-and-rinse adhesive systems, phosphoric acid etching of mineralized dentin solubilizes the mineral crystallites and replaces them with bound and unbound water. During the infiltration phase of dentin bonding, solvated adhesive resin comonomers are supposed to replace all of the unbound collagen water and polymerize into copolymers. A recently published review suggested that dental monomers are too large to enter and displace water from tightly-packed collagen molecules. Conversely, recent work from the authors' laboratory demonstrated that HEMA and TEGDMA freely equilibrate with water-saturated dentin matrices. However, because adhesive blends are solvated in organic solvents, those solvents may remove enough free water to allow collagen molecules to come close enough to exclude adhesive monomer permeation. The present study analyzed the size-exclusion characteristics of dentin collagen, using a gel permeation-like column chromatography technique, filled with dentin powder instead of Sephadex beads as the stationary phase. The elution volumes of different sized test molecules, including adhesive resin monomers, studied in both water-saturated dentin, and again in ethanol-dehydrated dentin powder, showed that adhesive resin monomers can freely diffuse into both hydrated and dehydrated collagen molecules. Under these in vitro conditions, all free and some of the loosely-bound water seems to have been removed by ethanol. These results validate the concept that adhesive resin monomers can permeate tightly-bound water in ethanol-saturated collagen molecules during infiltration by etch-and-rinse adhesives. It has been reported that collagen molecules in dentin matrices are packed too close together to allow permeation of adhesive monomers between them. Resin infiltration, in this view, would be limited to extrafibrillar spaces. Our work suggests that monomers equilibrate with collagen water in both water and ethanol-saturated dentin matrices. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effects of antibacterial primers with quaternary ammonium and nano-silver on S. mutans impregnated in human dentin blocks

PubMed Central

Cheng, Lei; Zhang, Ke; Weir, Michael D.; Liu, Huaibing; Zhou, Xuedong; Xu, Hockin H. K.

2013-01-01

Objectives Recent studies developed antibacterial bonding agents and composites containing a quaternary ammonium dimethacrylate (QADM) and nanoparticles of silver (NAg). The objectives of this study were to investigate: (1) the effect of antibacterial primers containing QADM and NAg on the inhibition of Streptococcus mutans (S. mutans) impregnated into dentin blocks for the first time, and (2) the effect of QADM or NAg alone or in combination, and the effect of NAg mass fraction, on S. mutans viability in dentin. Methods Scotchbond Multi-Purpose (SBMP) bonding agent was used. QADM and NAg were incorporated into SBMP primer. Six primers were tested: SBMP primer control, control + 10% QADM (mass %), control + 0.05% NAg, control + 10% QADM + 0.05% NAg, control + 0.1% NAg, and control + 10% QADM + 0.1% NAg. S. mutans were impregnated into dentin blocks, then a primer was applied. The viable colony-forming units (CFU) were then measured by harvesting the bacteria in dentin using a sonication method. Results Control + 10% QADM + 0.1% NAg had bacteria inhibition zone 8-fold that of control (p < 0.05). The sonication method successfully harvested bacteria from dentin blocks. Control + 10% QADM + 0.1% NAg inhibited S. mutans in dentin blocks, reducing the viable CFU in dentin by three orders of magnitude, compared to control dentin without primer. Using QADM+NAg was more effective than QADM alone. Higher NAg content increased the potency. Dentin shear bond strength was similar for all groups (p > 0.1). Significance Antibacterial primer with QADM and NAg were shown to inhibit the S. mutans impregnated into dentin blocks for the first time. Bonding agent containing QADM and NAg is promising to eradicate bacteria in tooth cavity and inhibit caries. The QADM and NAg may have applicability to other adhesives, cements, sealants and composites. PMID:23422420

Effect of application mode on interfacial morphology and chemistry between dentin and self-etch adhesives

PubMed Central

Zhang, Ying; Wang, Yong

2012-01-01

Objective To investigate the influence of application mode on the interfacial morphology and chemistry between dentin and self-etch adhesives with different aggressiveness. Methods The occlusal one-third of the crown was removed from un-erupted human third molars, followed by abrading with 600 grit SiC under water. Rectangular dentin slabs were prepared by sectioning the tooth specimens perpendicular to the abraded surfaces. The obtained dentin slabs were treated with one of the two one-step self-etch adhesives: Adper Easy Bond (AEB, PH~2.5) and Adper Prompt L-Pop (APLP, PH~0.8) with (15s, active application) or without (15s, inactive application) agitation. The dentin slabs were fractured and the exposed adhesive/dentin (A/D) interfaces were examined with micro-Raman spectroscopy and scanning electron microscopy (SEM). Results The interfacial morphology, degree of dentin demineralization (DD) and degree of conversion (DC) of the strong self-etch adhesive APLP showed more significant dependence on the application mode than the mild AEB. APLP exhibited inferior bonding at the A/D interface if applied without agitation, evidenced by debonding from the dentin substrate. The DDs and DCs of the APLP with agitation were higher than those of without agitation in the interface, in contrast to the comparable DD and DC values of two AEB specimen groups with different application modes. Raman spectral analysis revealed the important role of chemical interaction between acid monomers of self-etch adhesives and dentin in the above observations. Conclusion The chemical interaction with dentin is especially important for improving the DC of the strong self-etching adhesive at the A/D interface. Agitation could benefit polymerization efficacy of the strong self-etch adhesive through enhancing the chemical interaction with tooth substrate. PMID:23153573

Effect of additional etching and ethanol-wet bonding on the dentin bond strength of one-step self-etch adhesives

PubMed Central

Ahn, Joonghee; Jung, Kyoung-Hwa; Son, Sung-Ae; Hur, Bock; Kwon, Yong-Hoon

2015-01-01

Objectives This study examined the effects of additional acid etching on the dentin bond strength of one-step self-etch adhesives with different compositions and pH. The effect of ethanol wetting on etched dentin bond strength of self-etch adhesives was also evaluated. Materials and Methods Forty-two human permanent molars were classified into 21 groups according to the adhesive types (Clearfil SE Bond [SE, control]; G-aenial Bond [GB]; Xeno V [XV]; Beauti Bond [BB]; Adper Easy Bond [AE]; Single Bond Universal [SU]; All Bond Universal [AU]), and the dentin conditioning methods. Composite resins were placed on the dentin surfaces, and the teeth were sectioned. The microtensile bond strength was measured, and the failure mode of the fractured specimens was examined. The data were analyzed statistically using two-way ANOVA and Duncan's post hoc test. Results In GB, XV and SE (pH ≤ 2), the bond strength was decreased significantly when the dentin was etched (p < 0.05). In BB, AE and SU (pH 2.4 - 2.7), additional etching did not affect the bond strength (p > 0.05). In AU (pH = 3.2), additional etching increased the bond strength significantly (p < 0.05). When adhesives were applied to the acid etched dentin with ethanol-wet bonding, the bond strength was significantly higher than that of the no ethanol-wet bonding groups, and the incidence of cohesive failure was increased. Conclusions The effect of additional acid etching on the dentin bond strength was influenced by the pH of one-step self-etch adhesives. Ethanol wetting on etched dentin could create a stronger bonding performance of one-step self-etch adhesives for acid etched dentin. PMID:25671215

Microtensile bond strength of etch-and-rinse and self-etching adhesives to intrapulpal dentin after endodontic irrigation and setting of root canal sealer.

PubMed

Wattanawongpitak, Nipaporn; Nakajima, Masatoshi; Ikeda, Masaomi; Foxton, Richard M; Tagami, Junji

2009-02-01

To evaluate the effect of endodontic irrigation regimens and calcium hydroxide root canal sealer (Sealapex) on the microtensile bond strengths (muTBS) of dual-curing resin composite (Clearfil DC Core Automix) to the intrapulpal dentin. Forty standardized coronal-half root canal dentin specimens obtained from human premolars were divided into 4 groups: group A, no treatment (control); group B, Sealapex; group C, NaOCl/Sealapex; group D, EDTA/NaOCl/Sealapex. After 7 days of storage in 100% relative humidity, Sealapex was removed. Dentin surfaces were bonded with adhesives, either etch-and-rinse (Single Bond) or self-etching (Clearfil SE Bond), and built up with resin composite. The bonded specimens were trimmed into an hourglass shape with a 1-mm2 cross-sectional area for microtensile testing (n = 20). The muTBS to intrapulpal dentin was analyzed using two-way ANOVA and Dunnett's TC test. Two teeth of each group were prepared for micromorphological analysis of dentin surface. The root canal sealer with or without endodontic irrigation significantly affected the bond strengths of resin composite to intrapulpal dentin compared with the control group (p < 0.05). There were no significant differences in muTBS of each experimental group between etch-and-rinse and self-etching adhesives (p > 0.05). The dentin surface was covered with a mud-like material after sealer application for 7 days. The root canal sealer reduced the muTBS of dual-curing resin composite with etch-and-rinse and self-etching adhesive systems to intrapulpal dentin. Treatment with EDTA followed by NaOCI prior to obturation caused an additional reduction in muTBS of both adhesive systems to intrapulpal dentin.

Influence of the dentinal wall on the pH of sodium hypochlorite during root canal irrigation.

PubMed

Macedo, Ricardo Gomes; Herrero, Noemi Pascual; Wesselink, Paul; Versluis, Michel; van der Sluis, Luc

2014-07-01

The purpose of this study was to evaluate the influence of dentin on the pH levels of different concentrations of sodium hypochlorite (NaOCl) solutions over time and to evaluate if preconditioning of dentin with 17% EDTA or agitation of the NaOCl solution influences these pH levels. A novel clinically representative model that scales with the ratio of the irrigant volume to the dentin surface area of a human root canal was used. Three standardized bovine dentin bars (2 × 2 × 10 mm) were placed in a plastic test tube. A total of 150 tubes were distributed in 29 groups. In the first experiment, the pH of various NaOCl solutions, with different concentrations (3%, 6%, and 9%) and starting pH levels (5 and 12), was monitored during exposure to dentin between 10 and 300 seconds. In a second experiment, the effect of agitation (45 Hz) and pretreatment of dentin with 17% EDTA on the pH levels of various NaOCl solutions was studied after 30 seconds of exposure to dentin. The short-term chemical stability of the tested solutions was assessed for both the concentration and the pH. The exposure time (P < .001) and concentration of the NaOCl solution (P < .011) significantly influence the pH level after exposure to dentin. However, the change in pH is too small to induce a change in the irrigant antimicrobial/tissue dissolution capacity. Agitation of the irrigant and preconditioning of the dentin did not alter the pH (P > .05). Both the pH 5 and pH 12 solutions were chemically stable for 1 hour. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

The mechanical properties of human dentin for 3-D finite element modeling: Numerical and analytical evaluation.

PubMed

Grzebieluch, Wojciech; Będziński, Romuald; Czapliński, Tomasz; Kaczmarek, Urszula

2017-07-01

The FEM is often used in investigations of dentin loading conditions; however, its anisotropy is mostly neglected. The purpose of the study was to evaluate the anisotropy and the elastic properties of an equivalent homogenous material model of human dentin as well as to compare isotropic and anisotropic dentin FE-models. Analytical and numerical dentin homogenization according to Luciano and Barbero was performed and E-modulus (E), Poisson's ratios (v) G-modulus (G) were calculated. The E-modulus of the dentin matrix was 28.0 GPa, Poisson's ratio (v) was 0.3; finite element models of orthotropic and isotropic dentin were created, loaded and compared using Ansys® 14.5 and CodeAster® 11.2 software. Anisotropy of the dentin ranged from 6.9 to 35.2%. E-modulus and G-modulus were as follows: E1 = 22.0-26.0 GPa, E2/E3 = 15.7-23.0 GPa; G12/G13 = 6.96-9.35 GPa and G23 = 6.08-8.09 GPa (highest values in the superficial layer). In FEM analysis of the displacement values were higher in the isotropic than in the orthotropic model, reaching up to 16% by shear load, 37% by compression and 23% in the case of shear with bending. Strain values were higher in the isotropic model, up to 35% for the shear load, 31% for compression and 35% in the case of shear with bending. The decrease in the volumetric fraction and diameter of tubules increased the G and E values. Anisotropy of the dentin applied during FEM analysis decreased the displacements and strain values. The numerical and analytical homogenization of dentin showed similar results.

Effect of tooth substrate and porcelain thickness on porcelain veneer failure loads in vitro.

PubMed

Ge, Chunling; Green, Chad C; Sederstrom, Dalene A; McLaren, Edward A; Chalfant, James A; White, Shane N

2017-12-19

Bonded porcelain veneers are widely used esthetic restorations. High success and survival rates have been reported, but failures do occur. Fractures are the commonest failure mode. Minimally invasive or thin veneers have gained popularity. Increased enamel and porcelain thickness improve the strength of veneers bonded to enamel, but less is known about dentin or mixed substrates. The purpose of this in vitro study was to measure the influences of tooth substrate type (all-enamel, all-dentin, or half-dentin-half-enamel) and veneer thickness on the loads needed to cause initial and catastrophic porcelain veneer failure. Model discoid porcelain veneer specimens of varying thicknesses were bonded to the flattened facial surfaces of incisors with different enamel and dentin tooth substrates, artificially aged, and loaded to failure with a small sphere. Initial and catastrophic fracture events were identified and analyzed statistically and fractographically. Fracture events included initial Hertzian cracks, intermediate radial cracks, and catastrophic gross failure. All specimens retained some porcelain after catastrophic failure. Cement failure occurred at the cement-porcelain interface not at the cement-tooth interface. Porcelain veneers bonded to enamel were substantially stronger and more damage-tolerant than those bonded to dentin or mixed substrates. Increased porcelain thickness substantially raised the loads to catastrophic failure on enamel substrates but only moderately raised the loads to catastrophic failure on dentin or mixed substrates. The veneers bonded to half-dentin-half-enamel behaved remarkably like those bonded wholly to dentin. Porcelain veneers bonded to enamel were substantially stronger and more damage-tolerant than those bonded to dentin or half-enamel-half dentin. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Validation of a Cariogenic Biofilm Model to Evaluate the Effect of Fluoride on Enamel and Root Dentine Demineralization.

PubMed

Fernández, Constanza E; Tenuta, Livia M A; Cury, Jaime A

2016-01-01

Due to gingival recession both enamel and root dentine are at risk of developing caries. Both tissues are exposed to a similar environment, however there is not a validated model to evaluate the effect of fluoride on these dental substrates simultaneously. Hence, this study aimed to validate a caries model to evaluate the effect of fluoride to prevent demineralization on enamel and root-dentine. Streptococcus mutans UA159 biofilms were formed on saliva-coated bovine enamel and root dentine slabs (n = 12 per group) mounted in the same well of culture plates. The biofilms were exposed 8×/day to 10% sucrose and treated 2×/day with fluoridated solutions containing 0, 150, 450, or 1,350 ppm F; thus, simulating the use of low to high fluoride concentration toothpastes. The pH values of the culture medium was monitored 2×/day as a biofilm acidogenicity indicator. After 96 h, biofilms were collected for fluoride concentration analysis. The percentage of surface hardness loss (%SHL) was calculated for slabs. The fluoride uptake by the enamel and dentine was also determined. The model showed a dose-response because the biofilm and fluoride uptake increased and %SHL decreased at increasing fluoride concentrations (p < 0.05). Fluoride in the biofilm formed on dentine and fluoride uptake by dentine were higher than those for enamel. With the same fluoride concentration treatment, the percentage of reduction of demineralization was lower for dentine than for enamel. In conclusion, the model was validated in terms of a dose-response effect of fluoride on enamel and root dentine. Furthermore, the findings support the clinical data, suggesting that higher fluoride concentrations are necessary to control caries of root dentine than of enamel.

Bioinspired toughening mechanism: lesson from dentin.

PubMed

An, Bingbing; Zhang, Dongsheng

2015-07-09

Inspired by the unique microstructure of dentin, in which the hard peritubular dentin surrounding the dentin tubules is embedded in the soft intertubular dentin, we explore the crack propagation in the bioinspired materials with fracture process zone possessing a dentin-like microstructure, i.e. the composite structure consisting of a soft matrix and hard reinforcements with cylindrical voids. A micromechanical model under small-scale yielding conditions is developed, and numerical simulations are performed, showing that the rising resistant curve (R-curve) is observed for crack propagation caused by the plastic collapse of the intervoid ligaments in the fracture process zone. The dentin-like microstructure in the fracture process zone exhibits enhanced fracture toughness, compared with the case of voids embedded in the homogeneous soft matrix. Further computational simulations show that the dentin-like microstructure can retard void growth, thereby promoting fracture toughness. The typical fracture mechanism of the bioinspired materials with fracture process zone possessing the dentin-like structure is void by void growth, while it is the multiple void interaction in the case of voids in the homogeneous matrix. Based on the results, we propose a bioinspired material design principle, which is that the combination of a hard inner material encompassing voids and a soft outer material in the fracture process zone can give rise to exceptional fracture toughness, achieving damage tolerance. It is expected that the proposed design principle could shed new light on the development of novel man-made engineering materials.

Direct Tensile Strength and Characteristics of Dentin Restored with All-Ceramic, Resin-Composite, and Cast Metal Prostheses Cemented with Resin Adhesives

PubMed Central

Piemjai, Morakot; Nakabayashi, Nobuo

2015-01-01

A dentin-cement-prosthesis complex restored with either all-porcelain, cured resin-composite, or cast base metal alloy and cemented with either of the different resin cements was trimmed into a mini-dumbbell shape for tensile testing. The fractured surfaces and characterization of the dentin-cement interface of bonded specimens were investigated using a Scanning Electron Microscope. A significantly higher tensile strength of all-porcelain (12.5 ± 2.2 MPa) than that of cast metal (9.2 ± 3.5 MPa) restorations was revealed with cohesive failure in the cement and failure at the prosthesis-cement interface in Super-Bond C&B group. No significant difference in tensile strength was found among the types of restorations using the other three cements with adhesive failure on the dentin side and cohesive failure in the cured resin. SEM micrographs demonstrated the consistent hybridized dentin in Super-Bond C&B specimens that could resist degradation when immersed in hydrochloric acid followed by NaOCl solutions whereas a detached and degraded interfacial layer was found for the other cements. The results suggest that when complete hybridization of resin into dentin occurs tensile strength at the dentin-cement is higher than at the cement-prosthesis interfaces. The impermeable hybridized dentin can protect the underlying dentin and pulp from acid demineralization, even if detachment of the prosthesis has occurred. PMID:26539520

Hydroxyl Ion Diffusion through Radicular Dentine When Calcium Hydroxide Is Used under Different Conditions

PubMed Central

Cai, Michael; Castro Salgado, Jacqueline

2018-01-01

Calcium hydroxide’s anti-bacterial action relies on high pH. The aim here was to investigate hydroxyl ion diffusion through dentine under different conditions. Teeth were divided into control (n = 4) and four experimental groups (n = 10): Group 1—no medicament; Group 2—Calmix; Group 3—Calmix/Ledermix; Group 4—Calasept Plus/Ledermix; Group 5—Pulpdent/smear layer. Deep (inner dentine) and shallow (outer dentine) cavities were cut into each root. pH was measured in these cavities for 12 weeks. The inner and outer dentine pH in Group 2 was significantly higher than all groups. Inner dentine pH in Group 3 was slightly higher than that in Group 4 initially but subsequently comparable. After Day 2, Group 5 had significantly lower pH than Groups 3 and 4. The outer dentine pH in Group 3 started higher than that in Groups 4 and 5, but by Day 28 the difference was insignificant. The time for the inner dentine to reach maximum pH was one week for Group 2 and four weeks for Groups 3 and 4. The time for the outer dentine to reach maximum pH was eight weeks for all experimental groups. Mixing different Ca(OH)2 formulations with Ledermix gave similar hydroxyl ion release but pH and total diffusion was lower than Ca(OH)2 alone. The smear layer inhibited diffusion. PMID:29342093

[Attrition, dentin apposition and protein synthesis in the pulp and desmodont of young and old rats].

PubMed

Schroeder, H E; Münzel-Pedrazzoli, S

1994-01-01

Occlusal attrition and responsive adaptations in the pulp-dentinal unit are still problematic. In this study, up to 2 years-old rats were used to measure the amount of occlusal attrition, of dentin apposition and of the incorporation of 3H-proline into the pulpal and periodontal ligament tissues. Two to four SIV-rats each, 45, 365 and 730 days of age, were once injected with 3H-proline 2 hours or 5 days prior to exitus. After cardiac perfusion, the molar blocks of both jaws were decalcified in EDTA and divided into bucco-oral and mesio-distal slices. The latter were embedded in Epon. Semithin sections served to measure the amount of attrition and of tertiary dentin apposition, as well as for autoradiographic labelling and determination of the rate of dentin apposition and proline incorporation in pulpal and periodontal ligament tissues. The results show that (1) the molar cusps lost up to 40% of their initial height during the two years of life, (2) occlusal dentin apposition in the intercuspal region led to an increase in dentinal thickness by 50 to 70%, while in the pulp horn region dentinal apposition occurred early in life and later did not keep phase with attrition, and (3) protein synthesis in pulp and periodontal ligament essentially did not change within the two years of life. These findings are related to that of other authors and discussed in connection with dentinal innervation.

Characterization of transparent dentin in attrited teeth using optical coherence tomography.

PubMed

Mandurah, Mona M; Sadr, Alireza; Bakhsh, Turki A; Shimada, Yasushi; Sumi, Yasunori; Tagami, Junji

2015-05-01

Attrition and wear of tooth surface occur with aging and result in loss of enamel, with exposure and histological changes in dentin. Dealing with attrited teeth and restoration of the lost tissue are clinically challenging. The main objective of this study is to characterize the exposed transparent dentin in the occlusal surface of attrited teeth by optical coherence tomography (OCT). Naturally attrited, extracted human teeth with occlusal-transparent dentin were investigated in comparison to sound and carious teeth. The teeth were subjected to OCT imaging and then cross-sectioned and polished. OCT B-scans were compared to light microscopy images of the same cross section. In OCT images, some changes were evident at the transparent dentin in attrited teeth. An OCT attenuation coefficient parameter (μ t) was derived based on the Beer-Lambert law as a function of backscatter signal slope. The mean values of μ t were 1.05 ± 0.3, 2.23 ± 0.4, and 0.61 ± 0.27 mm(-1) for sound, carious, and transparent dentins, respectively. One-way ANOVA with Tukey's post-hoc showed a significant difference between groups (p < 0.05). Physiological changes in transparent dentin that involve deposition of mineral casts in the dentinal tubules lead to lower attenuation of OCT signal. OCT has a potential role to detect transparent dentin on the surface of attrited teeth and can be used in the future as a clinical adjunct tool.

Bacterial invasion into radicular dentine-an in vitro study.

PubMed

Stauffacher, Simone; Lussi, Adrian; Nietzsche, Sandor; Neuhaus, Klaus W; Eick, Sigrun

2017-06-01

We wanted to investigate differences in invasiveness into radicular dentinal tubules by monocultured and co-cultured bacteria frequently found in infected root canals. Fifty-one human roots were incubated for 8 weeks with monocultured Streptococcus gordonii ATCC 10558, Streptococcus sanguinis ATCC 10556, and with five capnophiles/anaerobes as well as with capnophiles/anaerobes co-cultured with a streptococcal species. Thereafter, bacterial samples were cultured from the inner, middle, and outer third of the root dentine of longitudinally broken teeth (n = 5). In addition, scanning electron microscopy (SEM) images were obtained. Single gram-positive species were able to penetrate into the middle and outer third of the root dentine. Fusobacterium nucleatum ATCC 25586 was not found in any of the dentine specimens. Prevotella intermedia ATCC 25611 and Porphyromonas gingivalis ATCC 33277 were found in the inner and middle third. The bacterial load of streptococci was higher in all thirds in co-cultures compared to single infections. In co-cultures with streptococci, Actinomyces oris ATCC 43146 was found in the outer third in 9/10 samples, whereas P. intermedia ATCC 25611 was not detectable inside dentine. Co-culture with S. sanguinis ATCC 10556 enabled F. nucleatum ATCC 25586 to invade dentine; SEM images showed that F. nucleatum ATCC 25586 had a swollen shape. Invasiveness of bacteria into dentinal tubules is species-specific and may change depending on culturing as a single species or co-culturing with other bacteria. Oral streptococci may promote or inhibit invasion of capnophiles/anaerobes into radicular dentine.

Influence of Er,Cr:YSGG laser treatment on the microtensile bond strength of adhesives to dentin.

PubMed

Cardoso, Marcio Vivan; Coutinho, Edurado; Ermis, R Banu; Poitevin, André; Van Landuyt, Kirsten; De Munck, Jan; Carvalho, Rubens C R; Lambrechts, Paul; Van Meerbeek, Bart

2008-02-01

In light of the concept of minimally invasive dentistry, erbium lasers have been considered as an alternative technique to the use of diamond burs for cavity preparation. The purpose of this study was to assess the bonding effectiveness of adhesives to Er,Cr:YSGG laser-irradiated dentin using irradiation settings specific for cavity preparation. Fifty-four midcoronal dentin surfaces, obtained from sound human molars, were irradiated with an Er,Cr:YSGG laser or prepared with a diamond bur using a high-speed turbine. One etch-and-rinse (Optibond FL/Kerr) and three self-etching adhesives (Adper Prompt L-Pop/3M ESPE, Clearfil SE Bond/Kuraray, and Clearfil S3 Bond/Kuraray) were used to bond the composite to dentin. The microtensile bond strength (microTBS) was determined after 24 h of storage in water at 37 degrees C. The Kruskal-Wallis test was used to determine pairwise statistical differences (p < 0.05). Prepared dentin surfaces, adhesive interfaces, and failure patterns were analyzed using a stereomicroscope and Field-emission gun Scanning Electron Microscopy (Feg-SEM). Significantly lower microTBS was observed to laser-irradiated than to bur-cut dentin (p < 0.05), irrespective of the adhesive employed. Feg-SEM photomicrographs of lased dentin revealed an imbricate patterned substrate and the presence of microcracks at the dentin surface. Morphological alterations produced by Er,Cr:YSGG laser-irradiation adversely influence the bonding effectiveness of adhesives to dentin.

In Vivo Effect of Calcium Hydroxide and Resin-modified Glass Ionomer Cement on Carious Dentin in Young Permanent Molars: An Ultrastructural and Macroscopic Study.

PubMed

Opal, Shireen; Garg, Shalini; Sharma, Deepak; Dhindsa, Abhishek; Jatana, Isha

2017-01-15

The purpose of this study was to evaluate macroscopically and ultrastructurally the effect of calcium hydroxide cement (CH) and resin-modified glass ionomer cement (RMGIC) compared with gutta percha (control) as a lining material on carious dentin after partial caries removal and sealing. Twenty-seven permanent molars with deep carious lesions underwent partial caries removal with the application of CH, RMGIC, or gutta percha (control) and were then sealed for three months. After a partial caries removal and sealing period, the dentin was macroscopically assessed (for color, consistency, and humidity) and further analyzed by scanning electron microscope to assess the ultrastructural changes in dentin (lumen size, mineralization of tubules, occlusion of tubules by cements, and bacterial ingress). The effect of treatment in each group was statistically analyzed. Dentin darkening and hardening were observed after the sealing period in all groups. However, there was no difference in the color after treatment among the three groups. It was observed that RMGIC showed a significant reduction in the size of the lumen compared to CH and the control. Partial caries removal and sealing resulted in dentin hardening, darkening, and dentin remineralization, irrespective of the dentin protection used.

Effect of Dentin Wetness on the Bond Strength of Universal Adhesives.

PubMed

Choi, An-Na; Lee, Ji-Hye; Son, Sung-Ae; Jung, Kyoung-Hwa; Kwon, Yong Hoon; Park, Jeong-Kil

2017-10-25

The effects of dentin wetness on the bond strength and adhesive interface morphology of universal adhesives have been investigated using micro-tensile bond strength (μTBS) testing and confocal laser scanning microscopy (CLSM). Seventy-two human third molars were wet ground to expose flat dentin surfaces. They were divided into three groups according to the air-drying time of the dentin surfaces: 0 (without air drying), 5, and 10 s. The dentin surfaces were then treated with three universal adhesives: G-Premio Bond, Single Bond Universal, and All-Bond Universal in self-etch or etch-and-rinse mode. After composite build up, a μTBS test was performed. One additional tooth was prepared for each group by staining the adhesives with 0.01 wt % of Rhodamine B fluorescent dye for CLSM analysis. The data were analyzed statistically using ANOVA and Tukey's post hoc tests (α = 0.05). Two-way ANOVA showed significant differences among the adhesive systems and dentin moisture conditions. An interaction effect was also observed ( p < 0.05). One-way ANOVA showed that All-Bond Universal was the only material influenced by the wetness of the dentin surfaces. Wetness of the dentin surface is a factor influencing the micro-tensile bond strength of universal adhesives.

Effect of Dentin Wetness on the Bond Strength of Universal Adhesives

PubMed Central

Lee, Ji-Hye; Son, Sung-Ae; Jung, Kyoung-Hwa; Kwon, Yong Hoon

2017-01-01

The effects of dentin wetness on the bond strength and adhesive interface morphology of universal adhesives have been investigated using micro-tensile bond strength (μTBS) testing and confocal laser scanning microscopy (CLSM). Seventy-two human third molars were wet ground to expose flat dentin surfaces. They were divided into three groups according to the air-drying time of the dentin surfaces: 0 (without air drying), 5, and 10 s. The dentin surfaces were then treated with three universal adhesives: G-Premio Bond, Single Bond Universal, and All-Bond Universal in self-etch or etch-and-rinse mode. After composite build up, a μTBS test was performed. One additional tooth was prepared for each group by staining the adhesives with 0.01 wt % of Rhodamine B fluorescent dye for CLSM analysis. The data were analyzed statistically using ANOVA and Tukey’s post hoc tests (α = 0.05). Two-way ANOVA showed significant differences among the adhesive systems and dentin moisture conditions. An interaction effect was also observed (p < 0.05). One-way ANOVA showed that All-Bond Universal was the only material influenced by the wetness of the dentin surfaces. Wetness of the dentin surface is a factor influencing the micro-tensile bond strength of universal adhesives. PMID:29068404

The measurement of enamel and dentine abrasion by tooth whitening products using an in situ model.

PubMed

Joiner, A; Collins, L Z; Cox, T F; Pickles, M J; Weader, E; Liscombe, C; Holt, J S

2005-01-01

To determine the enamel and dentine wear of two whitening toothpastes using an in situ model with ex vivo brushing. Human enamel/dentine (approximately 50:50) blocks (approximately 4 x 4mm) were placed in the upper buccal aspects of full or partial dentures of a group of 25 subjects. Subjects brushed the specimens ex vivo with either a calcium carbonate/perlite or silica containing whitening toothpaste under exaggerated conditions as compared to normal for 30 s, twice per day. Specimens were removed after 4, 8 and 12 weeks and the wear to the enamel and dentine was determined. Enamel wear was determined by change in Knoop indent length and dentine wear was determined from the enamel-dentine step height, measured using optical profilometry. The mean wear after 12 weeks was for enamel 0.27 and 0.19 microns, and for dentine 34.3 and 61.1 microns, for the calcium carbonate/perlite and silica toothpastes respectively. There were no significant differences between products after 12 weeks. The rate of wear was found to decrease throughout the duration of the study. There were no significant differences between the two whitening toothpastes in terms of enamel and dentine wear after 12 weeks brushing.

Carbodiimide Inactivation of MMPs and Effect on Dentin Bonding

PubMed Central

Mazzoni, A.; Apolonio, F.M.; Saboia, V.P.A.; Santi, S.; Angeloni, V.; Checchi, V.; Curci, R.; Di Lenarda, R.; Tay, F.R.; Pashley, D.H.; Breschi, L.

2014-01-01

The use of protein cross-linking agents during bonding procedures has been recently proposed to improve bond durability. This study aimed to use zymography and in situ zymography techniques to evaluate the ability of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) cross-linker to inhibit matrix metalloproteinase (MMP) activity. The hypotheses tested were that: (1) bonding procedures increase dentin gelatinolytic activity and (2) EDC pre-treatment prevents this enzymatic activity. The zymographic assay was performed on protein extracts obtained from dentin powder treated with Optibond FL or Scotchbond 1XT with or without 0.3M EDC pre-treatment. For in situ zymography, adhesive/dentin interfaces were created with the same adhesives applied to acid-etched dentin slabs pre-treated or not with EDC conditioner. Zymograms revealed increased expression of dentin endogenous MMP-2 and -9 after adhesive application, while the use of EDC as a primer inactivated dentin gelatinases. Results of in situ zymograpy showed that hybrid layers of tested adhesives exhibited intense collagenolytic activity, while almost no fluorescence signal was detected when specimens were pre-treated with EDC. The correlative analysis used in this study demonstrated that EDC could contribute to inactivate endogenous dentin MMPs within the hybrid layer created by etch-and-rinse adhesives. PMID:24334409

Remineralization of artificial dentinal caries lesions by biomimetically modified Mineral Trioxide Aggregate

PubMed Central

Qi, Yi-pin; Li, Nan; Niu, Li-na; Primus, Carolyn M.; Ling, Jun-Qi; Pashley, David H.; Tay, Franklin R.

2011-01-01

Fluoride-releasing restorative materials are available for remineralization of enamel and root caries. However, dentin remineralization is more difficult than enamel remineralization due to the paucity of apatite seed crystallites along the lesion surface for heterogeneous crystal growth. Extracellular matrix proteins play critical roles in controlling apatite nucleation/growth in collagenous tissues. This study examined the remineralization efficacy of mineral trioxide aggregate (MTA) in phosphate-containing simulated body fluid (SBF) by incorporating polyacrylic acid and sodium tripolyphosphate as biomimetic analogs of matrix proteins for remineralizing caries-like dentin. Artificial caries-like dentin lesions incubated in SBF were remineralized over a 6-week period using MTA or MTA containing biomimetic analogs in the absence or presence of dentin adhesive application. Lesion depths and integrated mineral loss were monitored with micro-computed tomography. Ultrastructure of baseline and remineralized lesions were examined by transmission electron microscopy. Dentin remineralization was best achieved using MTA containing biomimetic analogs regardless of whether an adhesive was applied; dentinal tubules within the remineralized dentin were occluded by apatite. It is concluded that the MTA version employed in the study may be doped with biomimetic analogs for remineralization of unbonded and bonded artificial caries-like lesions in the presence of SBF. PMID:22085925

Remineralization of artificial dentinal caries lesions by biomimetically modified mineral trioxide aggregate.

PubMed

Qi, Yi-pin; Li, Nan; Niu, Li-na; Primus, Carolyn M; Ling, Jun-Qi; Pashley, David H; Tay, Franklin R

2012-02-01

Fluoride-releasing restorative materials are available for remineralization of enamel and root caries. However, remineralization of dentin is more difficult than remineralization of enamel due to the paucity of apatite seed crystallites along the lesion surface for heterogeneous crystal growth. Extracellular matrix proteins play critical roles in controlling apatite nucleation/growth in collagenous tissues. This study examined the remineralization efficacy of mineral trioxide aggregate (MTA) in phosphate-containing simulated body fluid (SBF) by incorporating polyacrylic acid and sodium tripolyphosphate as biomimetic analogs of matrix proteins for remineralizing caries-like dentin. Artificial caries-like dentin lesions incubated in SBF were remineralized over a 6 week period using MTA alone or MTA containing biomimetic analogs in the absence or presence of dentin adhesive application. Lesion depths and integrated mineral loss were monitored with microcomputed tomography. The ultrastructure of baseline and remineralized lesions was examined by transmission electron microscopy. Dentin remineralization was best achieved using MTA containing biomimetic analogs regardless of whether an adhesive was applied; dentinal tubules within the remineralized dentin were occluded by apatite. It is concluded that the version of MTA employed in this study may be doped with biomimetic analogs for remineralization of unbonded and bonded artificial caries-like lesions in the presence of SBF. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

PLGA nanoparticles as chlorhexidine-delivery carrier to resin-dentin adhesive interface.

PubMed

Priyadarshini, Balasankar Meera; Mitali, Kakran; Lu, Thong Beng; Handral, Harish K; Dubey, Nileshkumar; Fawzy, Amr S

2017-07-01

To characterize and deliver fabricated CHX-loaded PLGA-nanoparticles inside micron-sized dentinal-tubules of demineralized dentin-substrates and resin-dentin interface. Nanoparticles fabricated by emulsion evaporation were assessed in-vitro by different techniques. Delivery of drug-loaded nanoparticles to demineralized dentin substrates, interaction with collagen matrix, and ex-vivo CHX-release profiles using extracted teeth connected to experimental setup simulating pulpal hydrostatic pressure were investigated. Furthermore, nanoparticles association/interaction with a commercial dentin-adhesive applied to demineralized dentin substrates were examined. The results showed that the formulated nanoparticles demonstrated attractive physicochemical properties, low cytotoxicity, potent antibacterial efficacy, and slow degradation and gradual CHX release profiles. Nanoparticles delivered efficiently inside dentinal-tubules structure to sufficient depth (>10μm) against the simulated upward pulpal hydrostatic-pressure, even after bonding-resins infiltration and were attached/retained on collagen-fibrils. These results verified the potential significance of this newly introduced drug-delivery therapeutic strategy for future clinical applications and promote for a new era of future dental research. This innovative drug-delivery strategy has proven to be a reliable method for delivering treatments that could be elaborated for other clinical applications in adhesive and restorative dentistry. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Biomimetic remineralization of demineralized dentine using scaffold of CMC/ACP nanocomplexes in an in vitro tooth model of deep caries.

PubMed

Chen, Zhen; Cao, Shansong; Wang, Haorong; Li, Yanqiu; Kishen, Anil; Deng, Xuliang; Yang, Xiaoping; Wang, Yinghui; Cong, Changhong; Wang, Huajun; Zhang, Xu

2015-01-01

Currently, it is still a tough task for dentists to remineralize dentine in deep caries. The aim of this study was to remineralize demineralized dentine in a tooth model of deep caries using nanocomplexes of carboxymethyl chitosan/amorphous calcium phosphate (CMC/ACP) based on mimicking the stabilizing effect of dentine matrix protein 1 (DMP1) on ACP in the biomineralization of dentine. The experimental results indicate that CMC can stabilize ACP to form nanocomplexes of CMC/ACP, which is able to be processed into scaffolds by lyophilization. In the single-layer collagen model, ACP nanoparticles are released from scaffolds of CMC/ACP nanocomplexes dissolved and then infiltrate into collagen fibrils via the gap zones (40 nm) to accomplish intrafibrillar mineralization of collagen. With this method, the completely demineralized dentine was partially remineralized in the tooth mode. This is a bottom-up remineralizing strategy based on non-classical crystallization theory. Since nanocomplexes of CMC/ACP show a promising effect of remineralization on demineralized dentine via biomimetic strategy, thereby preserving dentinal tissue to the maximum extent possible, it would be a potential indirect pulp capping (IPC) material for the management of deep caries during vital pulp therapy based on the concept of minimally invasive dentistry (MID).

Biomimetic Remineralization of Demineralized Dentine Using Scaffold of CMC/ACP Nanocomplexes in an In Vitro Tooth Model of Deep Caries

PubMed Central

Chen, Zhen; Cao, Shansong; Wang, Haorong; Li, Yanqiu; Kishen, Anil; Deng, Xuliang; Yang, Xiaoping; Wang, Yinghui; Cong, Changhong; Wang, Huajun; Zhang, Xu

2015-01-01

Currently, it is still a tough task for dentists to remineralize dentine in deep caries. The aim of this study was to remineralize demineralized dentine in a tooth model of deep caries using nanocomplexes of carboxymethyl chitosan/amorphous calcium phosphate (CMC/ACP) based on mimicking the stabilizing effect of dentine matrix protein 1 (DMP1) on ACP in the biomineralization of dentine. The experimental results indicate that CMC can stabilize ACP to form nanocomplexes of CMC/ACP, which is able to be processed into scaffolds by lyophilization. In the single-layer collagen model, ACP nanoparticles are released from scaffolds of CMC/ACP nanocomplexes dissolved and then infiltrate into collagen fibrils via the gap zones (40 nm) to accomplish intrafibrillar mineralization of collagen. With this method, the completely demineralized dentine was partially remineralized in the tooth mode. This is a bottom-up remineralizing strategy based on non-classical crystallization theory. Since nanocomplexes of CMC/ACP show a promising effect of remineralization on demineralized dentine via biomimetic strategy, thereby preserving dentinal tissue to the maximum extent possible, it would be a potential indirect pulp capping (IPC) material for the management of deep caries during vital pulp therapy based on the concept of minimally invasive dentistry (MID). PMID:25587986

Potential effects of tooth-brushing on human dentin wear following exposure to acidic soft drinks.

PubMed

Choi, S; Park, K-H; Cheong, Y; Moon, S W; Park, Y-G; Park, H-K

2012-08-01

This study used scanning electron microscopy and atomic force microscopy to examine the short-term potential effects of brushing time and the start-time of tooth-brushing after demineralization on primary dentin wear in vitro. Thirty-six noncarious primary central incisors were assigned to 12 experimental groups. Exposure to cola drinks was used to initiate the demineralization process. Three brushing times (5, 15 and 30 s) and four start-times of brushing (0, 30, 60 and 120 min) after an erosive attack were used for the abrasion process. Tooth-brushing the softened dentin surface led to increases in the open tubular fraction and microstructural changes on the dentin surface. Brushing immediately after exposure to cola resulted in the greatest irreversible dentin loss, whereas brushing 60 or 120 min after pretreatment resulted in the least irreversible dentin loss. However, brushing time had no effect on the irreversible loss of dentin wear. Based on these experimental results, tooth-brushing should be performed at least 60 min after consuming a cola drink to achieve the desired tooth cleaning and avoid the introduction of surface lesions on dentin. © 2012 The Authors Journal of Microscopy © 2012 Wadsworth Center, New York State Department of Health.

Comparison of nanoparticular hydroxyapatite pastes of different particle content and size in a novel scapula defect model

PubMed Central

Hruschka, Veronika; Tangl, Stefan; Ryabenkova, Yulia; Heimel, Patrick; Barnewitz, Dirk; Möbus, Günter; Keibl, Claudia; Ferguson, James; Quadros, Paulo; Miller, Cheryl; Goodchild, Rebecca; Austin, Wayne; Redl, Heinz; Nau, Thomas

2017-01-01

Nanocrystalline hydroxyapatite (HA) has good biocompatibility and the potential to support bone formation. It represents a promising alternative to autologous bone grafting, which is considered the current gold standard for the treatment of low weight bearing bone defects. The purpose of this study was to compare three bone substitute pastes of different HA content and particle size with autologous bone and empty defects, at two time points (6 and 12 months) in an ovine scapula drillhole model using micro-CT, histology and histomorphometry evaluation. The nHA-LC (38% HA content) paste supported bone formation with a high defect bridging-rate. Compared to nHA-LC, Ostim® (35% HA content) showed less and smaller particle agglomerates but also a reduced defect bridging-rate due to its fast degradation The highly concentrated nHA-HC paste (48% HA content) formed oversized particle agglomerates which supported the defect bridging but left little space for bone formation in the defect site. Interestingly, the gold standard treatment of the defect site with autologous bone tissue did not improve bone formation or defect bridging compared to the empty control. We concluded that the material resorption and bone formation was highly impacted by the particle-specific agglomeration behaviour in this study. PMID:28233833

Wind effects on long-span bridges: Probabilistic wind data format for buffeting and VIV load assessments

NASA Astrophysics Data System (ADS)

Hoffmann, K.; Srouji, R. G.; Hansen, S. O.

2017-12-01

The technology development within the structural design of long-span bridges in Norwegian fjords has created a need for reformulating the calculation format and the physical quantities used to describe the properties of wind and the associated wind-induced effects on bridge decks. Parts of a new probabilistic format describing the incoming, undisturbed wind is presented. It is expected that a fixed probabilistic format will facilitate a more physically consistent and precise description of the wind conditions, which in turn increase the accuracy and considerably reduce uncertainties in wind load assessments. Because the format is probabilistic, a quantification of the level of safety and uncertainty in predicted wind loads is readily accessible. A simple buffeting response calculation demonstrates the use of probabilistic wind data in the assessment of wind loads and responses. Furthermore, vortex-induced fatigue damage is discussed in relation to probabilistic wind turbulence data and response measurements from wind tunnel tests.

Histologic and SEM evaluation of caries removal and restoration in enamel and dentin using a pulsed fiber optic delivered Nd:YAG laser

NASA Astrophysics Data System (ADS)

White, Joel M.; Goodis, Harold E.; Kudler, Joel J.; Eakle, W. S.; Neev, Joseph

1994-09-01

The pulsed Nd:YAG laser has been proposed as an alternative to the dental handpiece for caries removal in enamel and dentin. The purpose of this study was to systematically evaluate, in vitro, the process of caries removal and restoration in enamel and dentin. The effectiveness of this device was investigated utilizing scanning electron microscopy to determine the behavior of dentin after laser treatment of artificially created carious lesions in dentin. Histologic sections of extracted teeth after laser treatment and restoration demonstrated successful caries removal and restoration using the pulsed fiber optic delivered Nd:YAG laser as compared to both high and low speed rotary instrumentation. The adjacent enamel and dentin were unaffected by the laser irradiation although slight carbonization was seen on the dentin surface. Thermocouples placed in the pulp chamber during caries removal confirmed previous studies that showed laser parameters up to 1 W and 10 Hz being the same as conventional caries removal in the amount of heat generated which reaches the pulp. The addition of air/water coolant decreased pulpal temperature.

On the R-curve behavior of human tooth enamel.

PubMed

Bajaj, Devendra; Arola, Dwayne D

2009-08-01

In this study the crack growth resistance behavior and fracture toughness of human tooth enamel were quantified using incremental crack growth measures and conventional fracture mechanics. Results showed that enamel undergoes an increase in crack growth resistance (i.e. rising R-curve) with crack extension from the outer to the inner enamel, and that the rise in toughness is a function of distance from the dentin enamel junction (DEJ). The outer enamel exhibited the lowest apparent toughness (0.67+/-0.12 MPam(0.5)), and the inner enamel exhibited a rise in the growth toughness from 1.13 MPam(0.5)/mm to 3.93 MPam(0.5)/mm. The maximum crack growth resistance at fracture (i.e. fracture toughness (K(c))) ranged from 1.79 to 2.37 MPam(0.5). Crack growth in the inner enamel was accompanied by a host of mechanisms operating from the micro- to the nano-scale. Decussation in the inner enamel promoted crack deflection and twist, resulting in a reduction of the local stress intensity at the crack tip. In addition, extrinsic mechanisms such as bridging by unbroken ligaments of the tissue and the organic matrix promoted crack closure. Microcracking due to loosening of prisms was also identified as an active source of energy dissipation. In summary, the unique microstructure of enamel in the decussated region promotes crack growth toughness that is approximately three times that of dentin and over ten times that of bone.

Disulfide Bridges: Bringing Together Frustrated Structure in a Bioactive Peptide.

PubMed

Zhang, Yi; Schulten, Klaus; Gruebele, Martin; Bansal, Paramjit S; Wilson, David; Daly, Norelle L

2016-04-26

Disulfide bridges are commonly found covalent bonds that are usually believed to maintain structural stability of proteins. Here, we investigate the influence of disulfide bridges on protein dynamics through molecular dynamics simulations on the cysteine-rich trypsin inhibitor MCoTI-II with three disulfide bridges. Correlation analysis of the reduced cyclic peptide shows that two of the three disulfide distances (Cys(11)-Cys(23) and Cys(17)-Cys(29)) are anticorrelated within ∼1 μs of bridge formation or dissolution: when the peptide is in nativelike structures and one of the distances shortens to allow bond formation, the other tends to lengthen. Simulations over longer timescales, when the denatured state is less structured, do not show the anticorrelation. We propose that the native state contains structural elements that frustrate one another's folding, and that the two bridges are critical for snapping the frustrated native structure into place. In contrast, the Cys(4)-Cys(21) bridge is predicted to form together with either of the other two bridges. Indeed, experimental chromatography and nuclear magnetic resonance data show that an engineered peptide with the Cys(4)-Cys(21) bridge deleted can still fold into its near-native structure even in its noncyclic form, confirming the lesser role of the Cys(4)-Cys(21) bridge. The results highlight the importance of disulfide bridges in a small bioactive peptide to bring together frustrated structure in addition to maintaining protein structural stability. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Evaluation of sub-surface penetration and bonding durability of self-etching primer systems to Er:YAG laser treated cervical dentin.

PubMed

He, Zhengdi; Chen, Lingling; Shimada, Yasushi; Tagami, Junji; Ruan, Shuangchen

2017-03-31

This study aimed to investigate self-etching bonding systems penetrating in sub-surface dentin layer after Er:YAG laser irradiation and micro-shear bonding durability over a period of 1 year. Dentin slices obtained from extracted human third molars were prepared. Two self-etching adhesive systems were evaluated: Clearfil SE Bond and Clearfil Tri-S Bond. Specimens were tested for micro-shear bond strength with one of the following treatments: Er:YAG laser irradiation and 600-grit silicon paper polishing at 24 h, 7 days, 6 months and 1 year. The adhesive interfaces between bonding agents and lased cervical dentin were studied. No hybrid layer could be observed for lased dentin. The slim resin tags could be seen penetrating through the lased subsurface layer. Bond strength to lased dentin after 6 months and 1 year were significantly decreased (p<0.05).

Cysteine Cathepsins in Human Carious Dentin

PubMed Central

Nascimento, F.D.; Minciotti, C.L.; Geraldeli, S.; Carrilho, M.R.; Pashley, D.H.; Tay, F.R.; Nader, H.B.; Salo, T.; Tjäderhane, L.; Tersariol, I.L.S.

2011-01-01

Matrix metalloproteinases (MMPs) are important in dentinal caries, and analysis of recent data demonstrates the presence of other collagen-degrading enzymes, cysteine cathepsins, in human dentin. This study aimed to examine the presence, source, and activity of cysteine cathepsins in human caries. Cathepsin B was detected with immunostaining. Saliva and dentin cysteine cathepsin and MMP activities on caries lesions were analyzed spectrofluorometrically. Immunostaining demonstrated stronger cathepsins B in carious than in healthy dentin. In carious dentin, cysteine cathepsin activity increased with increasing depth and age in chronic lesions, but decreased with age in active lesions. MMP activity decreased with age in both active and chronic lesions. Salivary MMP activities were higher in patients with active than chronic lesions and with increasing lesion depth, while cysteine cathepsin activities showed no differences. The results indicate that, along with MMPs, cysteine cathepsins are important, especially in active and deep caries. PMID:21248362

Comparison of effects of ProTaper, HeroShaper, and Gates Glidden Burs on cervical dentin thickness and root canal volume by using multislice computed tomography.

PubMed

Mahran, Abeer H; AboEl-Fotouh, Mona M

2008-10-01

The purpose of this study was to compare the effects of 3 different instruments used to prepare curved root canals on the remaining cervical dentin thickness and total amount of dentin removed from root canals during instrumentation by using multislice computed tomography. Mesiobuccal canals of 45 mandibular first molars with curvature between 30-40 degrees were divided into 3 equal groups: ProTaper, Hero Shaper, and Gates Glidden Bur with Flex-R hand file. Cervical dentin thickness and canal volume were measured before and after instrumentation by using multislice computed tomography and image analysis software. The results indicated that ProTaper removed significantly less cervical dentin from distal wall of the root (dangerous zone) than HeroShaper and Gates Glidden Bur (P < .05). The total dentin removed during canal instrumentation was significantly more with ProTaper system (P < .05).

Ex vivo fracture resistance of endodontically treated maxillary central incisors restored with fiber-reinforced composite posts and experimental dentin posts

PubMed Central

Kathuria, Ambica; Kavitha, M; Khetarpal, Suchit

2011-01-01

Aim: To compare the fracture resistance of teeth restored with fiber-reinforced composite (FRC) posts and experimental dentin posts milled from human root dentin. Materials and Methods: Thirty maxillary central incisors were divided into three groups of ten each. Twenty teeth were restored with FRC posts and solid dentin posts and numbered as Groups 2 and 3 respectively while Group 1 acted as the control, without any post. The teeth were loaded at 135° angle to their long axes after core build-up and the failure loads were recorded. Results: One-way Analysis of Variance (ANOVA) and Bonferroni multiple comparisons revealed a significant difference among test groups with the control group showing the highest fracture resistance, followed by the dentin post group and lastly the FRC post group. Conclusions: Teeth restored with dentin posts exhibited better fracture resistance than those restored with FRC posts. PMID:22144812

Effects of Er:YAG laser irradiation on human dentin: polarizing microscopic, light microscopic and microradiographic observations, and FT-IR analysis.

PubMed

Ishizaka, Yaeko; Eguro, Toru; Maeda, Toru; Tanaka, Hisayoshi

2002-01-01

The effects of Er:YAG laser irradiation on dentin have not been sufficiently investigated. The purpose of this study was to investigate the effects of Er:YAG laser irradiation on dentin. After cavities were prepared using Er:YAG laser irradiation or rotary cutting instruments, histological observations of cavity-floor dentin utilizing polarizing microscopy, microradiography and light microscopy, and analysis of composition of cavity-floor dentin using Fourier-transformed (FT-IR) spectrometry were conducted. In the laser-treated side, a deeply stained basophilic layer was observed. The number of odontoblastic processes present was obviously less in the laser-treated side than in the bur-treated side. FT-IR analysis revealed that compared to the bur-treated side, a broad background peak at around 1,600 cm(-1) was present. Er:YAG laser irradiation might have denatured the organic materials of dentin. Copyright 2002 Wiley-Liss, Inc.

Water evaporation from substrate tooth surface during dentin treatments.

PubMed

Kusunoki, Mizuho; Itoh, Kazuo; Gokan, Yuka; Nagai, Yoshitaka; Tani, Chihiro; Hisamitsu, Hisashi

2011-01-01

The purpose of this study was to evaluate changes in the quantity of water evaporation from tooth surfaces. The amount of water evaporation was measured using Multi probe adapter MPA5 and Tewameter TM300 (Courage+Khazaka Electric GmbH, Köln, Germany) after acid etching and GM priming of enamel; and after EDTA conditioning and GM priming of dentin. The results indicated that the amount of water evaporation from the enamel surface was significantly less than that from the dentin. Acid etching did not affect the water evaporation from enamel, though GM priming significantly decreased the evaporation (83.48 ± 15.14% of that before priming). The evaporation from dentin was significantly increased by EDTA conditioning (131.38 ± 42.08% of that before conditioning) and significantly reduced by GM priming (80.26 ± 7.43% of that before priming). It was concluded that dentin priming reduced water evaporation from the dentin surface.

23 CFR 650.407 - Application for bridge replacement or rehabilitation.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 23 Highways 1 2012-04-01 2012-04-01 false Application for bridge replacement or rehabilitation... Rehabilitation Program § 650.407 Application for bridge replacement or rehabilitation. (a) Agencies participate... agency for review and processing. The State is responsible for submitting the six computer card format or...

23 CFR 650.407 - Application for bridge replacement or rehabilitation.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 23 Highways 1 2013-04-01 2013-04-01 false Application for bridge replacement or rehabilitation... Rehabilitation Program § 650.407 Application for bridge replacement or rehabilitation. (a) Agencies participate... agency for review and processing. The State is responsible for submitting the six computer card format or...

23 CFR 650.407 - Application for bridge replacement or rehabilitation.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 23 Highways 1 2014-04-01 2014-04-01 false Application for bridge replacement or rehabilitation... Rehabilitation Program § 650.407 Application for bridge replacement or rehabilitation. (a) Agencies participate... agency for review and processing. The State is responsible for submitting the six computer card format or...

In-vitro Thermal Maps to Characterize Human Dental Enamel and Dentin.

PubMed

Lancaster, Paula; Brettle, David; Carmichael, Fiona; Clerehugh, Val

2017-01-01

The crown of a human tooth has an outer layer of highly-mineralized tissue called enamel, beneath which is dentin, a less-mineralized tissue which forms the bulk of the tooth-crown and root. The composition and structure of enamel and dentin are different, resulting in different thermal properties. This gives an opportunity to characterize enamel and dentin from their thermal properties and to visually present the findings as a thermal map. The thermal properties of demineralized enamel and dentin may also be sufficiently different from sound tissue to be seen on a thermal map, underpinning future thermal assessment of caries. The primary aim of this novel study was to produce a thermal map of a sound, human tooth-slice to visually characterize enamel and dentin. The secondary aim was to map a human tooth-slice with demineralized enamel and dentin to consider future diagnostic potential of thermal maps for caries-detection. Two human slices of teeth, one sound and one demineralized from a natural carious lesion, were cooled on ice, then transferred to a hotplate at 30°C where the rewarming-sequence was captured by an infra-red thermal camera. Calculation of thermal diffusivity and thermal conductivity was undertaken, and two methods of data-processing used customized software to produce thermal maps from the thermal characteristic-time-to-relaxation and heat-exchange. The two types of thermal maps characterized enamel and dentin. In addition, sound and demineralized enamel and dentin were distinguishable within both maps. This supports thermal assessment of caries and requires further investigation on a whole tooth.

Effect of smear layer deproteinization on bonding of self-etch adhesives to dentin: a systematic review and meta-analysis

PubMed Central

Alshaikh, Khaldoan H.; Mahmoud, Salah H.

2018-01-01

Objectives The aim of this systematic review was to critically analyze previously published studies of the effects of dentin surface pretreatment with deproteinizing agents on the bonding of self-etch (SE) adhesives to dentin. Additionally, a meta-analysis was conducted to quantify the effects of the above-mentioned surface pretreatment methods on the bonding of SE adhesives to dentin. Materials and Methods An electronic search was performed using the following databases: Scopus, PubMed and ScienceDirect. The online search was performed using the following keywords: ‘dentin’ or ‘hypochlorous acid’ or ‘sodium hypochlorite’ and ‘self-etch adhesive.’ The following categories were excluded during the assessment process: non-English articles, randomized clinical trials, case reports, animal studies, and review articles. The reviewed studies were subjected to meta-analysis to quantify the effect of the application time and concentration of sodium hypochlorite (NaOCl) and hypochlorous acid (HOCl) deproteinizing agents on bonding to dentin. Results Only 9 laboratory studies fit the inclusion criteria of this systematic review. The results of the meta-analysis revealed that the pooled average microtensile bond strength values to dentin pre-treated with deproteinizing agents (15.71 MPa) was significantly lower than those of the non-treated control group (20.94 MPa). Conclusions In light of the currently available scientific evidence, dentin surface pretreatment with deproteinizing agents does not enhance the bonding of SE adhesives to dentin. The HOCl deproteinizing agent exhibited minimal adverse effects on bonding to dentin in comparison with NaOCl solutions. PMID:29765895

Molecular detection of bacteria associated to caries activity in dentinal lesions.

PubMed

Neves, Beatriz Gonçalves; Stipp, Rafael Nóbrega; da Silva Bezerra, Daniela; de Figueiredo Guedes, Sarah Florindo; Rodrigues, Lidiany Karla Azevedo

2017-07-01

This study aimed at identifying and quantifying Actinomyces naeslundii, Bifidobacterium spp., Streptococcus mitis group, Lactobacillus acidophilus, Lactobacillus casei group, Streptococcus gordonii, and Streptococcus mutans in active and inactive carious dentine lesions of children with early childhood caries by using quantitative polymerase chain reaction. Fifty-six dentin lesion samples, classified as active (n = 39) or inactive (n = 17), were collected from children aged from 2 to 5 years old. Dentinal-cavitated lesions were evaluated by Nyvad criteria for the assessment of caries lesion activity. Relative quantification revealed that Bifidobacterium spp. and the L. casei group were significantly more abundant in active dentin lesions (p < 0.05). Concentrations of A. naeslundii, S. mitis group, and S. gordonii were not significantly different when comparing dentin lesion activity. The relative proportion of S. mutans was significantly greater in inactive than in active lesions (p < 0.05). Bifidobacterium spp. and L. casei group demonstrated a positive correlation (p = 0.001) in active lesions. The positive detection of L. acidophilus (odds ratio = 15.1) and S. gordonii (odds ratio = 7.7) was significantly associated to the active lesions. The data indicate that higher detection levels of Bifidobacterium spp. and the L. casei group may be linked to dentin lesion activity. Additionally, the presence of L. acidophilus and S. gordonii was associated with lesion activity. Considering that information about the oral microbiota related to dentin caries activity status is relevant, this study provides insights to better understand the differences in the microbiotas between active and arrested dentin cavities.

Functional remineralization of carious dentin

NASA Astrophysics Data System (ADS)

Pugach, Megan Kardon

A primary goal of dental tissue engineering is the biological reconstruction of tooth substrate destroyed by caries or other diseases affecting tooth mineralization. Traditionally, dentists treat caries by using invasive techniques to remove the diseased dental tissue and restore the lesion, ideally preventing further progression of decay. Success in strategies associated with remineralization of enamel and root caries have contributed to the less invasive prospect of remineralization of dentinal carious lesions. The central hypothesis of this dissertation is that carious dentin lesions can be remineralized if the lesions contain residual mineral. Caries Detector (CD) stained zones (pink, light pink, transparent and normal) of arrested carious dentin lesions were characterized according to microstructure by atomic force microscopy (AFM) imaging, mineral content by digital transverse microradiography, and nanomechanical properties by AFM-based nanoindentation. CD-stained and unstained zones had significantly different microstructure, mineral content and nanomechanical properties. Furthermore, the most demineralized carious zone contained residual mineral. To obtain reproducible, standardized dentin caries lesions, we characterized the lesions from an artificial carious dentin lesion model using a 0.05M acetate demineralization buffer. The artificial caries-like lesions produced by the buffer had similar mineral content and nanomechanical properties in the stained and unstained zones as natural dentin lesions. Both natural and artificial lesions had significant correlations between mineral content and nanomechanical properties. Mineral crystallite size and shape was examined by small angle x-ray scattering. Both natural and artificial carious dentin had different mineral sizes than normal dentin. Collagen in natural and artificial carious dentin lesions was examined by trichrome stain, AFM high-resolution imaging, and UV resonance Raman spectroscopy, to determine if fibrils were intact and mineralization levels. It appeared that the collagen in the most demineralized pink zones of the lesions was intact and contained intrafibrillar mineral. Natural and artificial carious dentin lesions were treated with remineralization solutions containing different amounts of Ca2+ and PO 43-, with and without CO32- and with and without 2 ppm fluoride. The hydrated nanomechanical properties of the lesions were partially restored. This suggests that the most CD-stained zones of arrested dentin caries lesions may be remineralizable. These results suggest that remineralization as an approach of minimally invasive dentistry using non-invasive treatments to restore dental tissues is possible.

ArrayBridge: Interweaving declarative array processing with high-performance computing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xing, Haoyuan; Floratos, Sofoklis; Blanas, Spyros

Scientists are increasingly turning to datacenter-scale computers to produce and analyze massive arrays. Despite decades of database research that extols the virtues of declarative query processing, scientists still write, debug and parallelize imperative HPC kernels even for the most mundane queries. This impedance mismatch has been partly attributed to the cumbersome data loading process; in response, the database community has proposed in situ mechanisms to access data in scientific file formats. Scientists, however, desire more than a passive access method that reads arrays from files. This paper describes ArrayBridge, a bi-directional array view mechanism for scientific file formats, that aimsmore » to make declarative array manipulations interoperable with imperative file-centric analyses. Our prototype implementation of ArrayBridge uses HDF5 as the underlying array storage library and seamlessly integrates into the SciDB open-source array database system. In addition to fast querying over external array objects, ArrayBridge produces arrays in the HDF5 file format just as easily as it can read from it. ArrayBridge also supports time travel queries from imperative kernels through the unmodified HDF5 API, and automatically deduplicates between array versions for space efficiency. Our extensive performance evaluation in NERSC, a large-scale scientific computing facility, shows that ArrayBridge exhibits statistically indistinguishable performance and I/O scalability to the native SciDB storage engine.« less

Biomechanical comparison of four double-row speed-bridging rotator cuff repair techniques with or without medial or lateral row enhancement.

PubMed

Pauly, Stephan; Fiebig, David; Kieser, Bettina; Albrecht, Bjoern; Schill, Alexander; Scheibel, Markus

2011-12-01

Biomechanical comparison of four different Speed-Bridge configurations with or without medial or lateral row reinforcement. Reinforcement of the knotless Speed-Bridge double-row repair technique with additional medial mattress- or lateral single-stitches was hypothesized to improve biomechanical repair stability at time zero. Controlled laboratory study: In 36 porcine fresh-frozen shoulders, the infraspinatus tendons were dissected and shoulders were randomized to four groups: (1) Speed-Bridge technique with single tendon perforation per anchor (STP); (2) Speed-Bridge technique with double tendon perforation per anchor (DTP); (3) Speed-Bridge technique with medial mattress-stitch reinforcement (MMS); (4) Speed-Bridge technique with lateral single-stitch reinforcement (LSS). All repairs were cyclically loaded from 10-60 N up to 10-200 N (20 N stepwise increase) using a material testing device. Forces at 3 and 5 mm gap formation, mode of failure and maximum load to failure were recorded. The MMS-technique with double tendon perforation showed significantly higher ultimate tensile strength (338.9 ± 90.0 N) than DTP (228.3 ± 99.9 N), LSS (188.9 ± 62.5 N) and STP-technique (122.2 ± 33.8 N). Furthermore, the MMS-technique provided increased maximal force resistance until 3 and 5 mm gap formation (3 mm: 77.8 ± 18.6 N; 5 mm: 113.3 ± 36.1 N) compared with LSS, DTP and STP (P < 0.05 for each 3 and 5 mm gap formation). Failure mode was medial row defect by tendon sawing first, then laterally. No anchor pullout occurred. Double tendon perforation per anchor and additional medial mattress stitches significantly enhance biomechanical construct stability at time zero in this ex vivo model when compared with the all-knotless Speed-Bridge rotator cuff repair.

Assessment of the amount of remaining coronal dentine in root-treated teeth.

PubMed

Bandlish, R B; McDonald, A V; Setchell, D J

2006-10-01

There is currently no standardised technique to measure the amount of coronal dentine remaining in a root-treated tooth after crown preparation. The aim of this study was to develop a method of measuring remaining coronal dentine in root-treated teeth and to propose an index for grading tooth restorability. The study recruited 20 patients who had completed molar endodontic treatment at the Eastman Dental Hospital and had been prescribed an amalgam coronal-radicular core with a full coverage cast restoration. Using a series of interlocking special trays and impressions, a method was devised to produce a cast of the amount of remaining dentine coronal to the finish line after crown preparation. This cast was scanned using a laser profilometer and the volume of remaining dentine was calculated. A tooth restorability index (TRI) was developed to assess the strategic value of the remaining dentine. The TRI allowed scores of 0-3 in each sextant with a maximum score of 18 per tooth. Twenty teeth were scored by three examiners and the TRI scores varied from 2 to 13. The volume of coronal dentine varied from 61.73 to 232.22 mm(3). A tooth restorability index has been devised to assess the strategic value of remaining dentine. A Kappa statistic was calculated to produce values of 0.584, 0.688 and 0.720, giving moderate-good agreement between the examiners.

Resin-dentin interface of Scotchbond Multi-Purpose dentin adhesive.

PubMed

Griffiths, B M; Watson, T F

1995-08-01

To evaluate the interface between dentin, Scotchbond Multi-Purpose (SMP), and resin composite (Z100) using confocal fluorescence microscopy. Novel techniques were employed to view and record at video rate the application of the SMP primer and adhesive onto the dentin surface. The subsurface morphology of the dentin/restorative interface was also studied. To facilitate this study, the components of the adhesive system were labeled with fluorescent dyes. In an ideal situation, the primer and adhesive penetrated the dentin tubules, a distinct hybrid zone was formed and a thin layer of adhesive was observed at the interfacial region. However, the primed dentin surface was sensitive to disruption by the adhesive application brush during its placement, so that parts of the primer layer could be incorporated into the adhesive. This disruption could only be seen using confocal microscopy and a fluorescence labeling technique. Delamination of the primer layer was not observed when the adhesive film was thinned by air blowing. The application of an air stream to the cavity surface increased the penetration of the primer and adhesive along the dentin tubules, but also increased the thickness of the adhesive within irregularities on the cavity surface and at the cavity line angle. The cause of the problems in the handling properties of SMP may be the difference in viscosity between the two components (primer and adhesive) at the adhesive interface.

Desensitizing Agent Reduces Dentin Hypersensitivity During Ultrasonic Scaling: A Pilot Study

PubMed Central

Suda, Tomonari; Akiyama, Toshiharu; Takano, Takuya; Gokyu, Misa; Sudo, Takeaki; Khemwong, Thatawee; Izumi, Yuichi

2015-01-01

Background Dentin hypersensitivity can interfere with optimal periodontal care by dentists and patients. The pain associated with dentin hypersensitivity during ultrasonic scaling is intolerable for patient and interferes with the procedure, particularly during supportive periodontal therapy (SPT) for patients with gingival recession. Aim This study proposed to evaluate the desensitizing effect of the oxalic acid agent on pain caused by dentin hypersensitivity during ultrasonic scaling. Materials and Methods This study involved 12 patients who were incorporated in SPT program and complained of dentin hypersensitivity during ultrasonic scaling. We examined the availability of the oxalic acid agent to compare the degree of pain during ultrasonic scaling with or without the application of the dentin hypersensitivity agent. Evaluation of effects on dentin hypersensitivity was determined by a questionnaire and visual analog scale (VAS) pain scores after ultrasonic scaling. The statistical analysis was performed using the paired Student t-test and Spearman rank correlation coefficient. Results The desensitizing agent reduced the mean VAS pain score from 69.33 ± 16.02 at baseline to 26.08 ± 27.99 after application. The questionnaire revealed that >80% patients were satisfied and requested the application of the desensitizing agent for future ultrasonic scaling sessions. Conclusion This study shows that the application of the oxalic acid agent considerably reduces pain associated with dentin hypersensitivity experienced during ultrasonic scaling. This pain control treatment may improve patient participation and treatment efficiency. PMID:26501012

Heat Transfer Behavior across the Dentino-Enamel Junction in the Human Tooth

PubMed Central

Niu, Lin; Dong, Shao-Jie; Kong, Ting-Ting; Wang, Rong; Zou, Rui; Liu, Qi-Da

2016-01-01

During eating, the teeth usually endure the sharply temperature changes because of different foods. It is of importance to investigate the heat transfer and heat dissipation behavior of the dentino–enamel junction (DEJ) of human tooth since dentine and enamel have different thermophysical properties. The spatial and temporal temperature distributions on the enamel, dentine, and pulpal chamber of both the human tooth and its discontinuous boundaries, were measured using infrared thermography using a stepped temperature increase on the outer boundary of enamel crowns. The thermal diffusivities for enamel and dentine were deduced from the time dependent temperature change at the enamel and dentine layers. The thermal conductivities for enamel and dentine were calculated to be 0.81 Wm-1K-1 and 0.48 Wm-1K-1 respectively. The observed temperature discontinuities across the interfaces between enamel, dentine and pulp-chamber layers were due to the difference of thermal conductivities at interfaces rather than to the phase transformation. The temperature gradient distributes continuously across the enamel and dentine layers and their junction below a temperature of 42°C, whilst a negative thermal resistance is observed at interfaces above 42°C. These results suggest that the microstructure of the dentin-enamel junction (DEJ) junction play an important role in tooth heat transfer and protects the pulp from heat damage. PMID:27662186

Microorganism penetration in dentinal tubules of instrumented and retreated root canal walls. In vitro SEM study.

PubMed

Al-Nazhan, Saad; Al-Sulaiman, Alaa; Al-Rasheed, Fellwa; Alnajjar, Fatimah; Al-Abdulwahab, Bander; Al-Badah, Abdulhakeem

2014-11-01

This in vitro study aimed to investigate the ability of Candida albicans (C. albicans) and Enterococcus faecalis (E. faecalis) to penetrate dentinal tubules of instrumented and retreated root canal surface of split human teeth. Sixty intact extracted human single-rooted teeth were divided into 4 groups, negative control, positive control without canal instrumentation, instrumented, and retreated. Root canals in the instrumented group were enlarged with endodontic instruments, while root canals in the retreated group were enlarged, filled, and then removed the canal filling materials. The teeth were split longitudinally after canal preparation in 3 groups except the negative control group. The teeth were inoculated with both microorganisms separately and in combination. Teeth specimens were examined by scanning electron microscopy (SEM), and the depth of penetration into the dentinal tubules was assessed using the SMILE view software (JEOL Ltd). Penetration of C. albicans and E. faecalis into the dentinal tubules was observed in all 3 groups, although penetration was partially restricted by dentin debris of tubules in the instrumented group and remnants of canal filling materials in the retreated group. In all 3 groups, E. faecalis penetrated deeper into the dentinal tubules by way of cell division than C. albicans which built colonies and penetrated by means of hyphae. Microorganisms can easily penetrate dentinal tubules of root canals with different appearance based on the microorganism size and status of dentinal tubules.

Effect of acid fruit juices combined with electric or sonic toothbrushing on root dentin permeability--an in vitro study.

PubMed

Batitucci, Roberta Grasselli; Zandim, Daniela Leal; Rocha, Fernanda Regina Godoy; Pinheiro, Michele Carolina; Fontanari, Lucas Amaral; Sampaio, José Eduardo Cezar

2012-01-01

The purpose of this in vitro study was to quantify the alterations on human root dentin permeability after exposure to different acid fruit juices and to evaluate the effect of toothbrushing with electric or sonic toothbrush after acid exposure. The root dentin of 50 extracted third molars was exposed with a high speed bur. Crowns were sectioned above the cementoenamel junction and root fragments were used to prepare dentin specimens. Specimens were randomly assigned to 5 groups according to the fruit juice (kiwifruit, starfruit, green apple, pineapple and acerolla). Each specimen was connected to a hydraulic pressure apparatus to measure root dentin permeability using fluid filtration method after the following sequential steps: I) conditioning with 37% phosphoric acid for 30 s, II) root scaling, III) exposure to acid fruit juices for 5 min and IV) electric or sonic toothbrushing without dentifrice for 3 min. Data were analyzed statistically by the Wilcoxon and Mann-Whitney tests at 5% significance level. All fruit juices promoted a significant increase of dentin permeability while toothbrushing decreased it significantly (p<0.05). It may be concluded that all acid fruit juices increased root dentin permeability, while toothbrushing without dentifrice after acid exposure decreased the permeability. The toothbrush mechanism (electric or sonic) had no influence on the decrease of root dentin permeability.

Incomplete caries removal and indirect pulp capping in primary molars: a randomized controlled trial.

PubMed

Bressani, Ana Eliza Lemes; Mariath, Adriela Azevedo Souza; Haas, Alex Nogueira; Garcia-Godoy, Franklin; de Araujo, Fernando Borba

2013-08-01

To compare the effect of incomplete caries removal (ICR) and indirect pulp capping (IPC) with calcium hydroxide (CH) or an inert material (wax) on color, consistency and contamination of the remaining dentin of primary molars. This double-blind, parallel-design, randomized controlled trial included 30 children presenting one primary molar with deep caries lesion. Children were randomly assigned after ICR to receive IPC with CH or wax. All teeth were then restored with resin composite. Baseline dentin color and consistency were evaluated after ICR, and dentin samples were collected for contamination analyses using scanning electron microscopy. After 3 months, restorations were removed and the three parameters were re-evaluated. In both groups, dentin became significantly darker after 3 months. No cases of yellow dentin were observed after 3 months with CH compared to 33.3% of the wax cases (P < 0.05). A statistically significant difference over time was observed only for CH regarding consistency. CH stimulated a dentin hardening process in a statistically higher number of cases than wax (86.7% vs. 33.3%; P = 0.008). Contamination changed significantly over time in CH and wax without significant difference between groups. It was concluded that CH and wax arrested the carious process of the remaining carious dentin after indirect pulp capping, but CH showed superior dentin color and consistency after 3 months.

Mineral features of connective dental hard tissues in hypoplastic amelogenesis imperfecta.

PubMed

Kammoun, R; Behets, C; Mansour, L; Ghoul-Mazgar, S

2018-04-01

To explore the mineral features of dentin and cementum in hypoplastic Amelogenesis imperfecta AI teeth. Forty-four (44) teeth cleaned and free of caries were used: 20 control and 24 affected by hypoplastic amelogenesis imperfecta. Thirty-two teeth were studied by pQCT, cut in sections, and analyzed under microradiography, polarized light microscopy, and confocal Raman spectroscopy. Eight teeth were observed under scanning electron microscope. Four teeth were used for an X-ray diffraction. The mineral density data were analyzed statistically with the Mann-Whitney U test, using GraphPad InStat software. Both coronal dentin and radicular dentin were less mineralized in AI teeth when compared to control (respectively 6.2% and 6.8%; p < .001). Root dentinal walls were thin and irregular, while the cellular cementum layers were thick, reaching sometimes the cervical region of the tooth. Regular dentinal tubules and sclerotic dentin areas were noticed. Partially tubular or cellular dysplastic dentin and hyper-, normo-, or hypomineralized areas were noticed in the inter-radicular areas of hypoplastic AI teeth. The main mineral component was carbonate hydroxyapatite as explored by Raman spectroscopy and X-ray diffraction. Dentin and cementum in hypoplastic AI teeth are (i) hypomineralized, (ii) constituted of carbonate hydroxyapatite, and (iii) of non-homogenous structure. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. All rights reserved.

Heat Transfer Behavior across the Dentino-Enamel Junction in the Human Tooth.

PubMed

Niu, Lin; Dong, Shao-Jie; Kong, Ting-Ting; Wang, Rong; Zou, Rui; Liu, Qi-Da

During eating, the teeth usually endure the sharply temperature changes because of different foods. It is of importance to investigate the heat transfer and heat dissipation behavior of the dentino-enamel junction (DEJ) of human tooth since dentine and enamel have different thermophysical properties. The spatial and temporal temperature distributions on the enamel, dentine, and pulpal chamber of both the human tooth and its discontinuous boundaries, were measured using infrared thermography using a stepped temperature increase on the outer boundary of enamel crowns. The thermal diffusivities for enamel and dentine were deduced from the time dependent temperature change at the enamel and dentine layers. The thermal conductivities for enamel and dentine were calculated to be 0.81 Wm-1K-1 and 0.48 Wm-1K-1 respectively. The observed temperature discontinuities across the interfaces between enamel, dentine and pulp-chamber layers were due to the difference of thermal conductivities at interfaces rather than to the phase transformation. The temperature gradient distributes continuously across the enamel and dentine layers and their junction below a temperature of 42°C, whilst a negative thermal resistance is observed at interfaces above 42°C. These results suggest that the microstructure of the dentin-enamel junction (DEJ) junction play an important role in tooth heat transfer and protects the pulp from heat damage.

Mathematical simulation of the thermal diffusion in dentine irradiated with Nd:YAG laser using finite difference method

NASA Astrophysics Data System (ADS)

Moriyama, Eduardo H.; Zangaro, Renato A.; Lobo, Paulo D. d. C.; Villaverde, Antonio G. J. B.; Watanabe-Sei, Ii; Pacheco, Marcos T. T.; Otsuka, Daniel K.

2002-06-01

Thermal damage in dental pulp during Nd:YAG laser irradiation have been studied by several researchers; but due to dentin inhomogeneous structure, laser interaction with dentin in the hypersensitivity treatment are not fully understood. In this work, heat distribution profile on human dentine samples irradiated with Nd:YAG laser was simulated at surface and subjacent layers. Calculations were carried out using the Crank-Nicolson's finite difference method. Sixteen dentin samples with 1,5 mm of thickness were evenly distributed into four groups and irradiated with Nd:YAG laser pulses, according to the following scheme: (I) 1 pulse of 900 mJ, (II) 2 pulses of 450 mJ, (III) 3 pulses of 300 mJ, (IV) 6 pulses of 150 mJ; corresponding to a total laser energy of 900 mJ. The pulse interval was 300ms, the pulse duration of 900 ms and irradiated surface area of 0,005 mm2. Laser induced morphological changes in dentin were observed for all the irradiated samples. The heat distribution throughout the dentin layer, from the external dentin surface to the pulpal chamber wall, was calculated for each case, in order to obtain further information about the pulsed Nd:YAG laser-oral hard tissue interaction. The simulation showed significant differences in the final temperature at the pulpal chamber, depending on the exposition time and the energy contained in the laser pulse.

Effect of reducing acid etching time on bond strength to noncarious and caries-affected primary and permanent dentin.

PubMed

Scheffel, Débora Lopes Salles; Ricci, Hérica Adad; de Souza Costa, Carlos Alberto; Pashley, David Henry; Hebling, Josimeri

2013-01-01

The purpose was to evaluate the effect of acid etching time on the bond strength of a simplified etch-and-rinse adhesive system to noncarious and caries-affected dentin of primary and permanent teeth. Twenty-four extracted primary and permanent teeth were divided into three groups, according to the acid etching time. Four teeth from each group were exposed to a microbiological caries-inducing protocol. After caries removal, noncarious and caries-affected dentin surfaces were etched with 37 percent phosphoric acid for five, 10, or 15 seconds prior to the application of Prime & Bond NT adhesive. Crowns were restored with resin composite and prepared for microtensile testing. Data were submitted to Kruskal-Wallis and Mann-Whitney tests (α=0.05). Higher bond strengths were obtained for noncarious dentin vs. caries-affected dentin for both primary and permanent teeth. Reducing the acid etching time from 15 to five seconds did not affect the bond strength to caries-affected or noncarious dentin in primary teeth. For permanent teeth, lower bond strength values were observed when the noncarious dentin was etched for five seconds, while no difference was seen between 10 and 15 seconds. For Prime & Bond NT, the etching of dentin for five seconds could be recommended for primary teeth, while 10 seconds would be the minimum time for permanent teeth.

Influence of previous acid etching on bond strength of universal adhesives to enamel and dentin.

PubMed

Torres, Carlos Rocha Gomes; Zanatta, Rayssa Ferreira; Silva, Tatiane Josefa; Huhtala, Maria Filomena Rocha Lima; Borges, Alessandra Bühler

2017-01-01

The objective of this study was to evaluate the effect of acid pretreatment on the bond strength of composite resin bonded to enamel and dentin with 2 different universal self-etching adhesives. The null hypothesis was that the acid treatment performed prior to adhesive application would not significantly change the bond strength to enamel or dentin for either universal adhesive tested. A sample of 112 bovine incisors were selected and embedded in acrylic resin. Half were ground until a flat enamel surface was obtained, and the other half were polished until a 6 × 6-mm area of dentin was exposed, resulting into 2 groups (n = 56). The enamel and dentin groups were divided into 2 subgroups according to the adhesive system applied: Futurabond U or Scotchbond Universal. Each of these subgroups was divided into 2 additional subgroups (n = 14); 1 subgroup received phosphoric acid pretreatment, and 1 subgroup did not. The bond strength was assessed with a microtensile test. Data from enamel and dentin specimens were analyzed separately using 1-way analysis of variance. The acid pretreatment did not significantly change the bond strength of the adhesives tested, either to enamel (P = 0.4161) or to dentin (P = 0.4857). The acid etching pretreatment did not affect the bond strength to dentin and enamel when the tested universal multipurpose adhesive systems were used.

Toothbrushing before or after an acidic challenge to minimize tooth wear? An in situ/ex vivo study.

PubMed

Wiegand, Annette; Egert, Sebastian; Attin, Thomas

2008-02-01

To evaluate whether patients should be advised to perform toothbrushing before or after an acidic challenge to minimize enamel and dentin wear by brushing abrasion. The study was a two-period crossover design (A and B, each 14 days) in which three enamel and dentin specimens were fixed in intraoral appliances of 10 volunteers. The following regimens were performed three times a day with at least 4 hours in between: A: 20-second brushing treatment in an automatic brushing machine, 5 minutes intraoral exposure of the specimens, extraoral erosion of enamel and dentin specimens for 40 seconds or B: Extraoral erosion for 40 seconds, 5 minutes intraoral exposure of the specimens, 20-second brushing treatment in an automatic brushing machine. Enamel and dentin loss at the end of each 14-day regimen was assessed by profilometry and statistically analyzed by t-test. For all volunteers, mean enamel and dentin wear was significantly lower when brushing treatment was performed before erosion (A: enamel: 2.3 +/- 1.0 microm, dentin: 4.1 +/- 1.6 microm) than when brushing was applied after erosion (B: enamel: 6.4 +/- 3.0 microm, dentin: 15.3 +/- 6.8 microm). It was concluded that patients awaiting an erosive attack should perform toothbrushing prior to rather than after an acidic challenge to minimize enamel and dentin wear.

Comparison of propagation-based phase-contrast tomography approaches for the evaluation of dentin microstructure

NASA Astrophysics Data System (ADS)

Deyhle, Hans; Weitkamp, Timm; Lang, Sabrina; Schulz, Georg; Rack, Alexander; Zanette, Irene; Müller, Bert

2012-10-01

The complex hierarchical structure of human tooth hard tissues, enamel and dentin, guarantees function for decades. On the micrometer level the dentin morphology is dominated by the tubules, micrometer-narrow channels extending from the dentin-enamel junction to the pulp chamber. Their structure has been extensively studied, mainly with two-dimensional approaches. Dentin tubules are formed during tooth growth and their orientation is linked to the morphology of the nanometer-sized components, which is of interest for example for the development of bio-inspired dental fillings. Therefore, a method has to be identified that can access the three-dimensional organization of the tubules, e.g. density and orientation. Tomographic setups with pixel sizes in the sub-micrometer range allow for the three-dimensional visualization of tooth dentin tubules both in phase and absorption contrast modes. We compare high-resolution tomographic scans reconstructed with propagation based phase retrieval algorithms as well as reconstructions without phase retrieval concerning spatial and density resolution as well as rendering of the dentin microstructure to determine the approach best suited for dentin tubule imaging. Reasonable results were obtained with a single-distance phase retrieval algorithm and a propagation distance of about 75% of the critical distance of d2/λ, where d is the size of the smallest objects identifiable in the specimen and λ is the X-ray wavelength.

Dentin Biomodification: Strategies, Renewable Resources and Clinical Applications

PubMed Central

Bedran-Russo, Ana K.; Pauli, Guido F.; Chen, Shao-Nong; McAlpine, James; Castellan, Carina S.; Phansalkar, Rasika S; Aguiar, Thaiane R.; Vidal, Cristina M.P.; Napotilano, José; Nam, Joo-Won; Leme, Ariene A.

2014-01-01

Objectives The biomodification of dentin is a biomimetic approach, mediated by bioactive agents, to enhance and reinforce the dentin by locally altering the biochemistry and biomechanical properties. This review provides an overview of key dentin matrix components, targeting effects of biomodification strategies, the chemistry of renewable natural sources, and current research on their potential clinical applications. Methods The PubMed database and collected literature were used as a resource for peer-reviewed articles to highlight the topics of dentin hierarchical structure, biomodification agents, and laboratorial investigations of their clinical applications. In addition, new data is presented on laboratorial methods for the standardization of proanthocyanidin-rich preparations as a renewable source of plant-derived biomodification agents. Results Biomodification agents can be categorized as physical methods and chemical agents. Synthetic and naturally occurring chemical strategies present distinctive mechanism of interaction with the tissue. Initially thought to be driven only by inter- or intra-molecular collagen induced non-enzymatic collagen cross-linking, multiple interactions with other dentin components are fundamental for the long-term biomechanics and biostability of the tissue. Oligomeric proanthocyanidins show promising bioactivity, and their chemical complexity requires systematic evaluation of the active compounds to produce a fully standardized intervention material from renewable resource, prior to their detailed clinical evaluation. Significance Understanding the hierarchical structure of dentin and the targeting effect of the bioactive compounds will establish their use in both dentin-biomaterials interface and caries management. PMID:24309436

In vitro dentin permeability after application of Gluma® desensitizer as aqueous solution or aqueous fumed silica dispersion

PubMed Central

ISHIHATA, Hiroshi; FINGER, Werner J.; KANEHIRA, Masafumi; SHIMAUCHI, Hidetoshi; KOMATSU, Masashi

2011-01-01

Objectives To assess and to compare the effects of Gluma® Desensitizer (GDL) with an experimental glutaraldehyde and HEMA containing fumed silica dispersion (GDG) on dentin permeability using a chemiluminous tracer penetration test. Material and Methods Twenty disc-shaped dentin specimens were dissected from extracted human third molars. The dentin specimens were mounted in a split chamber device for determination of permeability under liquid pressure using a photochemical method. Ten specimens were randomly selected and allocated to the evaluation groups Gluma® Desensitizer as aqueous solution and glutaraldehyde/HEMA as fumed silica dispersion, respectively. Dentin disc permeability was determined at two pressure levels after removal of smear with EDTA, after albumin soaking, and after application of the desensitizing agents. Two desensitizer-treated and rinsed specimens of each group were examined by scanning electron microscopy (SEM) for surface remnants. Results Comparatively large standard deviations of the mean EDTA reference and albumin soaked samples permeability values reflected the differences of the dentin substrates. The mean chemiluminescence values of specimen treated with GDL and GDG, respectively, were significantly reduced after topical application of the desensitizing agents on albumin-soaked dentin. The effects of GDL and GDG on permeability were not significantly different. Treated specimens showed no surface remnants after rinsing. Conclusions The experimental desensitizer gel formulation reduced dentin permeability as effectively as the original Gluma® Desensitizer solution. PMID:21552716

Effect of an acid diet allied to sonic toothbrushing on root dentin permeability: an in vitro study.

PubMed

Pinto, Shelon Cristina Souza; Batitucci, Roberta Grasseli; Pinheiro, Michele Carolina; Zandim, Daniela Leal; Spin-Neto, Rubens; Sampaio, José Eduardo Cezar

2010-01-01

This study quantified alterations in root dentin permeability after exposure to different acid beverages. Twenty-five third molars were sectioned below the cementoenamel junction, the root segment was collected, and the pulp tissue was removed. The root segments were connected to a hydraulic pressure apparatus to measure the permeability of root dentin after the following sequential steps, with 5 specimens in each: 1) phosphoric acid etching for 30 s (maximum permeability), 2) root planning to create new smear layer, 3) exposure to different acid substances for 5 min (orange, cola drink, vinegar, white wine, lemon juice), 4) toothbrushing with sonic toothbrush for 3 min, 5) toothbrushing with sonic toothbrush plus dentifrice for 3 min. Considering step I as 100%, the data were converted into percentage and each specimen was its own control. Data were analyzed statistically by Kruskal-Wallis and Dunn's post test at 5% significance level. All acidic substances increased dentin permeability significantly after scraping (p< 0.05). Toothbrushing after exposure to acid substances decreased dentin permeability and the association with dentifrice accentuated the decrease (p< 0.05), except for the specimens treated with cola drink. Thus, it may be concluded that all tested acid fruit juices increased dentin permeability, and toothbrushing with or without dentifrice can decrease root dentin permeability after dentin exposure to acid diet.

Desensitizing Agent Reduces Dentin Hypersensitivity During Ultrasonic Scaling: A Pilot Study.

PubMed

Suda, Tomonari; Kobayashi, Hiroaki; Akiyama, Toshiharu; Takano, Takuya; Gokyu, Misa; Sudo, Takeaki; Khemwong, Thatawee; Izumi, Yuichi

2015-09-01

Dentin hypersensitivity can interfere with optimal periodontal care by dentists and patients. The pain associated with dentin hypersensitivity during ultrasonic scaling is intolerable for patient and interferes with the procedure, particularly during supportive periodontal therapy (SPT) for patients with gingival recession. This study proposed to evaluate the desensitizing effect of the oxalic acid agent on pain caused by dentin hypersensitivity during ultrasonic scaling. This study involved 12 patients who were incorporated in SPT program and complained of dentin hypersensitivity during ultrasonic scaling. We examined the availability of the oxalic acid agent to compare the degree of pain during ultrasonic scaling with or without the application of the dentin hypersensitivity agent. Evaluation of effects on dentin hypersensitivity was determined by a questionnaire and visual analog scale (VAS) pain scores after ultrasonic scaling. The statistical analysis was performed using the paired Student t-test and Spearman rank correlation coefficient. The desensitizing agent reduced the mean VAS pain score from 69.33 ± 16.02 at baseline to 26.08 ± 27.99 after application. The questionnaire revealed that >80% patients were satisfied and requested the application of the desensitizing agent for future ultrasonic scaling sessions. This study shows that the application of the oxalic acid agent considerably reduces pain associated with dentin hypersensitivity experienced during ultrasonic scaling. This pain control treatment may improve patient participation and treatment efficiency.

Effect of hyaluronic acid on morphological changes to dentin surfaces and subsequent effect on periodontal ligament cell survival, attachment, and spreading.

PubMed

Mueller, Andrea; Fujioka-Kobayashi, Masako; Mueller, Heinz-Dieter; Lussi, Adrian; Sculean, Anton; Schmidlin, Patrick R; Miron, Richard J

2017-05-01

Hyaluronic acid (HA) is a natural constituent of connective tissues and plays an important role in their development, maintenance, and regeneration. Recently, HA has been shown to improve wound healing. However, no basic in vitro study to date has investigated its mode of action. Therefore, the purpose of this study was to examine morphological changes of dentin surfaces following HA coating and thereafter investigate the influence of periodontal ligament (PDL) cell survival, attachment, and spreading to dentin discs. HA was coated onto dentin discs utilizing either non-cross-linked (HA) or cross-linked (HA cl) delivery systems. Morphological changes to dentin discs were then assessed using scanning electron microscopy (SEM). Thereafter, human PDL cells were seeded under three in vitro conditions including (1) dilution of HA (1:100), (2) dilution of HA (1:10), and (3) HA coated directly to dentin discs. Samples were then investigated for PDL cell survival, attachment, and spreading using a live/dead assay, cell adhesion assay, and SEM imaging, respectively. While control dentin discs demonstrated smooth surfaces both at low and high magnification, the coating of HA altered surface texture of dentin discs by increasing surface roughness. HA cl further revealed greater surface texture/roughness likely due to the cross-linking carrier system. Thereafter, PDL cells were seeded on control and HA coated dentin discs and demonstrated a near 100 % survival rate for all samples demonstrating high biocompatibility of HA at dilutions of both 1:100 and 1:10. Interestingly, non-cross-linked HA significantly increased cell numbers at 8 h, whereas cross-linked HA improved cell spreading as qualitatively assessed by SEM. The results from the present study demonstrate that both carrier systems for HA were extremely biocompatible and demonstrated either improved cell numbers or cell spreading onto dentin discs. Future in vitro and animal research is necessary to further characterize the optimal delivery system of HA for improved clinical use. HA is a highly biocompatible material that may improve PDL cell attachment or spreading on dentin.

The shear bond strength of self-adhesive resin cements to dentin and enamel: an in vitro study.

PubMed

Rodrigues, Raphaela F; Ramos, Carla M; Francisconi, Paulo A S; Borges, Ana Flávia S

2015-03-01

Clinicians continue to search for ways to simplify bonding procedures without compromising clinical efficacy. The purpose of this study was to evaluate the shear strength of self-adhesive cements RelyX U100 and RelyX U200, and conventional resin cement RelyX ARC to enamel and dentin after different surface treatments. The crowns of 120 bovine incisor teeth were separated from the roots and embedded in epoxy resin in polyvinyl chloride tubes. In each tooth, the area to be cemented was delimited with central holed adhesive tape. The teeth were distributed into 12 groups (n=10) according to the substrate; etched or not with 37% phosphoric acid; and cement type of enamel-U100, enamel-phosphoric acid-U100, enamel-U200, enamel-phosphoric acid-U200, enamel-ARC, enamel-phosphoric acid-ARC, dentin-U100, dentin-phosphoric acid-U100, dentin-U200, dentin-phosphoric acid-U200, dentin-ARC, and dentin-phosphoric acid-ARC. After 7 days of storage in artificial saliva, shear strength tests were performed by using a universal testing machine (0.5 mm/min). The data were analyzed with 3-way ANOVA and the Tukey test (α=.05). Fracture analysis was performed with a light microscope. Two specimens from each group were analyzed with a scanning electron microscope. In enamel, ARC (9.96 MPa) had higher shear strength (P=.038) than U100 (5.14 MPa); however, after surface etching, U100 (17.81 MPa) and U200 (17.52 MPa) had higher shear strength (P<.001). With dentin, no significant differences were observed (P=.999), except for dentin-ARC (0.34 MPa) (P=.001). Most fractures were of the adhesive type. U200 self-adhesive cement had similar bond strength to the ARC in enamel, but the combination with phosphoric acid had the best bond strength. For dentin, self-adhesive resin cements are equally effective alternatives to conventional resin cement. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Effect of different adhesion strategies on bond strength of resin composite to composite-dentin complex.

PubMed

Özcan, M; Pekkan, G

2013-01-01

Service life of discolored and abraded resin composite restorations could be prolonged by repair or relayering actions. Composite-composite adhesion can be achieved successfully using some surface conditioning methods, but the most effective adhesion protocol for relayering is not known when the composite restorations are surrounded with dentin. This study evaluated the effect of three adhesion strategies on the bond strength of resin composite to the composite-dentin complex. Intact maxillary central incisors (N=72, n=8 per subgroup) were collected and the coronal parts of the teeth were embedded in autopolymerized poly(methyl tfr54methacrylate) surrounded by a polyvinyl chloride cylinder. Cylindrical cavities (diameter: 2.6 mm; depth: 2 mm) were opened in the middle of the labial surfaces of the teeth using a standard diamond bur, and the specimens were randomly divided into three groups. Two types of resin composite, namely microhybrid (Quadrant Anterior Shine; AS) and nanohybrid (Grandio; G), were photo-polymerized incrementally in the cavities according to each manufacturer's recommendations. The composite-enamel surfaces were ground finished to 1200-grit silicone carbide paper until the dentin was exposed. The surfaces of the substrate composites and the surrounding dentin were conditioned according to one of the following adhesion protocols: protocol 1: acid-etching (dentin) + silica coating (composite) + silanization (composite) + primer (dentin) + bonding agent (dentin + composite); protocol 2: silica coating (composite) + acid-etching (dentin) + silanization (composite) + primer (dentin) + bonding agent (dentin + composite); and protocol 3: acid-etching (dentin) + primer (dentin) + silanization (composite) + bonding agent (dentin + composite). Applied primer and bonding agents were the corresponding materials of the composite manufacturer. Silica coating (CoJet sand, 30 μm) was achieved using a chairside air-abrasion device (distance: 10 mm; duration: four seconds in circular motion). After conditioning protocols, the repair resin was adhered to the substrate surfaces using transparent polyethylene molds (diameter: 3.6 mm) incrementally and photo-polymerized. The substrate-adherend combinations were as follows: AS-AS, G-G, AS-G. Shear force was applied to the adhesive interface in a Universal Testing Machine (crosshead speed: 1 mm/min). The types of failures were further evaluated and categorized as follows: 1) cohesive in the composite substrate and 2) adhesive at the interface. Bond strength values (MPa) were statistically analyzed using two-way analysis of variance and least significant difference post hoc tests (α=0.05). Significant effects of the adhesion strategy (p=0.006) and the composite type (p=0.000) were found. Interaction terms were not significant (p=0.292). Regardless of the substrate-adherend combination, protocol 1 (17-22 MPa) showed significantly higher results than did protocols 2 (15-17 MPa) and 3 (11-17 MPa) (p=0.028, p=0.002, respectively). The highest results were obtained from the G-G combination after all three protocols (17-22 MPa). The incidence of cohesive failures was more common when the substrate and the adherend were the same composite type (AS-AS: 87.5%, 87.5%, 75%; G-G: 100%, 75%, 50% for protocols 1, 2, and 3, respectively). When substrate and adherend were used interchangeably, adhesive failures were more frequent (25%, 50%, and 100% for protocol 1, 2, and 3, respectively). When the substrate and the adherend are of the same type, greater repair strength could be expected. In the repair of composites next to the dentin, depending on the composite type, conditioning the composite with silica coating and silanization after etching the dentin adds to the repair strength compared to the results obtained with silane application only.

Influence of temporary cement contamination on the surface free energy and dentine bond strength of self-adhesive cements.

PubMed

Takimoto, Masayuki; Ishii, Ryo; Iino, Masayoshi; Shimizu, Yusuke; Tsujimoto, Akimasa; Takamizawa, Toshiki; Ando, Susumu; Miyazaki, Masashi

2012-02-01

The surface free energy and dentine bond strength of self-adhesive cements were examined after the removal of temporary cements. The labial dentine surfaces of bovine mandibular incisors were wet ground with #600-grit SiC paper. Acrylic resin blocks were luted to the prepared dentine surfaces using HY Bond Temporary Cement Hard (HY), IP Temp Cement (IP), Fuji TEMP (FT) or Freegenol Temporary Cement (TC), and stored for 1 week. After removal of the temporary cements with an ultrasonic tip, the contact angle values of five specimens per test group were determined for the three test liquids, and the surface-energy parameters of the dentine surfaces were calculated. The dentine bond strengths of the self-adhesive cements were measured after removal of the temporary cements in a shear mode at a crosshead speed of 1.0mm/min. The data were subjected to one-way analysis of variance (ANOVA) followed by Tukey's HSD test. For all surfaces, the value of the estimated surface tension component γ(S)(d) (dispersion) was relatively constant at 41.7-43.3 mJm(-2). After removal of the temporary cements, the value of the γ(S)(h) (hydrogen-bonding) component decreased, particularly with FT and TC. The dentine bond strength of the self-adhesive cements was significantly higher for those without temporary cement contamination (8.2-10.6 MPa) than for those with temporary cement contamination (4.3-7.1 MPa). The γ(S) values decreased due to the decrease of γ(S)(h) values for the temporary cement-contaminated dentine. Contamination with temporary cements led to lower dentine bond strength. The presence of temporary cement interferes with the bonding performance of self-adhesive cements to dentine. Care should be taken in the methods of removal of temporary cement when using self-adhesive cements. Copyright © 2011 Elsevier Ltd. All rights reserved.

Expression patterns of nestin and dentin sialoprotein during dentinogenesis in mice.

PubMed

Quispe-Salcedo, Angela; Ida-Yonemochi, Hiroko; Nakatomi, Mitsushiro; Ohshima, Hayato

2012-04-01

Differentiated odontoblasts could not be identified by one unique phenotypic marker, but the combination of expression of dentin phosphoprotein (Dpp), dentin sialoprotein (Dsp), dentin matrix protein 1 (Dmp1), and nestin may be valuable for the assessment of these cells. However, the findings using these proteins remain controversial. This study aimed to compare two odontoblast differentiation markers: nestin and Dsp in the process of dentinogenesis in mice. We performed immunohistochemistry and/or in situ hybridization technique for nestin and Dsp using 3-week-old incisors as well as postnatal 1-day- to 8-week-old molars. Preodontoblasts began to express nestin and Dsp proteins and Dsp mRNA, which increased in their intensity according to the progress of odontoblast differentiation in both incisors and developing molars. Nestin was consistently expressed in the differentiated odontoblasts even after the completion of dentin matrix deposition. The expression of Dsp mRNA coincided with the odontoblast secretory activity for dentin matrix deposition. In contrast, other pulpal cells, predentin matrix and dentinal tubules also showed a positive reaction for Dsp protein in addition to differentiated odontoblasts. In conclusion, nestin is valuable as a differentiation marker for odontoblasts, whereas Dsp mRNA is a functional marker for their secretory activity.

In Vitro Evaluation of Dentin Tubule Occlusion for Novel Calcium Lactate Phosphate (CLP) Paste

PubMed Central

Yang, Jen-Chang; Hu, Hsin-Tai; Lee, Sheng-Yang; Hsieh, Sung-Chih; Huang, Pei-Chi; Ma, Chen-Feng; Ji, Dian-Yu; Chang, Liang-Yu; Teng, Nai-Chia

2017-01-01

Introduction: The objective of this in vitro study is to evaluate the effective and long-term occlusion of dentinal tubules using a novel calcium lactate phosphate (CLP) based desensitizing agent. Methods: Dentin disks (n = 9) were pre-etched using 1 M lactic acid for 30 s and individually treated with Colgate® Pro-Relief™ paste, CLP paste, and double distilled water (ddH2O) by a rubber-cupped handpiece. Dentin disks were analyzed under optical micrographs for pre-treatment, directly after treatment, and 14 days post-treatment. One-way ANOVA and post-hoc Tukey’s test were used to determine whether there were any statistically significant differences in dentinal tubule diameter. Results: A significant decrease occurred in the mean tubule diameter for dentin disks treated with CLP paste. A decrease was observed from 3.52 ± 0.83 µm to 2.62 ± 0.42 µm right after treatment, further decreasing to 1.71 ± 0.45 µm after immersion in artificial saliva for 14 days (p < 0.05). Conclusions: The results suggest that the CLP based desensitizing paste has remineralization properties and provides instant and lasting effectiveness in dentinal tubule occlusion. PMID:28772594

Deformation behavior of human enamel and dentin-enamel junction under compression.

PubMed

Zaytsev, Dmitry; Panfilov, Peter

2014-01-01

Deformation behavior under uniaxial compression of human enamel and dentin-enamel junction (DEJ) is considered in comparison with human dentin. This deformation scheme allows estimating the total response from all levels of the hierarchical composite material in contrast with the indentation, which are limited by the mesoscopic and microscopic scales. It was shown for the first time that dental enamel is the strength (up to 1850MPa) hard tissue, which is able to consider some elastic (up to 8%) and plastic (up to 5%) deformation under compression. In so doing, it is almost undeformable substance under the creep condition. Mechanical properties of human enamel depend on the geometry of sample. Human dentin exhibits the similar deformation behavior under compression, but the values of its elasticity (up to 40%) and plasticity (up to 18%) are much more, while its strength (up to 800MPa) is less in two times. Despite the difference in mechanical properties, human enamel is able to suppress the cracking alike dentin. Deformation behavior under the compression of the samples contained DEJ as the same to dentin. This feature allows a tooth to be elastic-plastic (as dentin) and wear resistible (as enamel), simultaneously. © 2013 Elsevier B.V. All rights reserved.

Antibacterial effects of Nd:YAG laser irradiation within root canal dentin.

PubMed

Klinke, T; Klimm, W; Gutknecht, N

1997-02-01

The microbial flora of the root canal dentin can cause failures in the conventional treatment of infected root canals if it cannot be sufficiently removed by preparation and chemical disinfection of the root canal. The aim of this study is to examine the bactericidal effects of neodymium:yttriumaluminum garnet (Nd:YAG) laser irradiation in the depth of the root canal dentin. Following sterilization, longitudinal section dentin slices of different thicknesses (100-1000 microns) were inoculated on one side with 4 microliters of a Streptococcus mutans suspension. The opposite sides of the dentin slices were then irradiated four times for 10-20 sec (according to the sample area) using the Nd:YAG laser at a setting of 1.5 W, 15 pps with a 200 microns glass fiber from an angle of about 5 degrees. The bacteria were then removed from the dentin using vibration and plated out on culture dishes that were selective for Streptococcus mutans. When compared with untreated control slices, counting of the colonies revealed a highly significant elimination of bacteria for all thicknesses following laser irradiation. Although the intensity of the laser irradiation decreased after penetration of a 1000-micron dentin slice, the bactericidal mode of action was still effective.

Multiscale characterization of partially demineralized superficial and deep dentin surfaces.

PubMed

Pelin, Irina M; Trunfio-Sfarghiu, Ana-Maria; Farge, Pierre; Piednoir, Agnes; Pirat, Christophe; Ramos, Stella M M

2013-08-01

The objective of this study was to address the following question: 'Which properties are modified in partially demineralized surfaces, compared with non-demineralized dentin surfaces, following orthophosphoric acid-etching as performed in clinical procedures?'. For this purpose, the complementary techniques atomic force microscopy/spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and contact angle measurements were used to provide a multiscale characterization of the dentin substrate undergoing the acidic preconditioning designed to enhance wetting. Special attention was given to the influence of the etching pretreatment on the nanomechanical properties at different levels of dentin surfaces, in both dry and hydrated conditions. The four-sided pyramid model (extended Hertz contact model) proved to be accurate for calculating the apparent Young's modulus, offering new information on the elasticity of dentin. The modulus value notably decreased following etching and surface hydration. This study underlines that after the acid etching pretreatment the contribution of the nanomechanical, morphological, and physicochemical modifications has a strong influence on the dentin adhesion properties and thus plays a significant role in the coupling of the adhesive-resin composite build-up material at the dentin surface. © 2013 Eur J Oral Sci.

Effect of Silver Nitrate and Sodium Fluoride with Tri-Calcium Phosphate on Streptococcus mutans and Demineralised Dentine.

PubMed

Yu, Ollie Yiru; Zhao, Irene Shuping; Mei, May Lei; Lo, Edward Chin-Man; Chu, Chun-Hung

2018-04-25

This study investigated the effect of 25% silver nitrate (AgNO₃) and 5% sodium fluoride (NaF) varnish with functionalized tri-calcium phosphate (fTCP) on a Streptococcus mutans ( S. mutans ) biofilm and dentine caries lesion. Demineralised dentine specimens were treated with 25% AgNO₃ and 5% NaF + fTCP (Group 1), 25% AgNO₃ and 5% NaF (Group 2), 25% AgNO₃ (Group 3), or water (Group 4). The specimens were subjected to a S. mutans biofilm challenge after treatment. The biofilm was then studied via scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and colony forming units (CFU). The specimens were assessed by micro-computed tomography, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). SEM and CLSM revealed less biofilm in Groups 1 to 3. The log 10 CFU of Groups 1 to 4 were 4.5 ± 0.7, 4.4 ± 0.9, 4.4 ± 0.9, and 6.7 ± 1.0, respectively (Groups 1, 2, 3 < 4, p < 0.001). The lesion depths of Groups 1 to 4 were 212.6 ± 20.1 µm, 280.8 ± 51.6 µm, 402.5 ± 61.7 µm, and 497.4 ± 67.2 µm, respectively (Groups 1 < 2 < 3 < 4, p < 0.001). XRD demonstrated silver chloride formation in Groups 1, 2, and 3. FTIR found the amide I: HPO₄ 2− values of the four groups were 0.22 ± 0.05, 0.25 ± 0.05, 0.41 ± 0.12, and 0.64 ± 0.14, respectively (Groups 1, 2 < 3 < 4; p < 0.001). In conclusion, this study revealed that AgNO₃ and NaF + fTCP reduced the damage of dentine caries by cariogenic biofilm.

Incidence of Dentinal Cracks after Root Canal Preparation with Twisted File Adaptive Instruments Using Different Kinematics.

PubMed

Karataş, Ertuğrul; Arslan, Hakan; Alsancak, Meltem; Kırıcı, Damla Özsu; Ersoy, İbrahim

2015-07-01

The purpose of the present study was to assess the effect of root canal instrumentation using Twisted File Adaptive instruments (Axis/SybronEndo, Orange, CA) with different kinematics (adaptive motion, 90° clockwise [CW]-30° counterclockwise [CCW], 150° CW-30° CCW, 210° CW-30° CCW, and continuous rotation) on crack formation. One hundred five mandibular central incisor teeth were selected. Fifteen teeth were left unprepared (control group), and the remaining 90 teeth were assigned to the 5 root canal shaping groups as follows (n = 15): adaptive motion, 90° CW-30° CCW, 150° CW-30° CCW, 210° CW-30° CCW, continuous rotation, and hand file. All the roots were sectioned horizontally at 3, 6, and 9 mm from the apex with a low-speed saw under water cooling, and the slices were then viewed through a stereomicroscope at 25× magnification. Digital images of each slice were captured using a camera to determine the presence of dentinal cracks. No cracks were observed in the control group, and the continuous rotation group had more cracks than the reciprocation groups (90° CW-30° CCW, 150° CW-30° CCW, and 210° CW-30° CCW) (P < .05). Both the continuous rotation and adaptive motion groups had significantly more dentinal cracks than the hand file group (P < .05). Regarding the different sections (3, 6, and 9 mm), there was a significant difference between the experimental groups at the 9-mm level (P < .05). The incidence of dentinal cracks is less with TF Adaptive instruments working in 210° CW-30° CCW reciprocating motion compared with working in continuous rotation and adaptive motion. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Enhanced Preliminary Assessment Report: Old Bridge Army Housing Units, Old Bridge, New Jersey

DTIC Science & Technology

1989-11-01

overlain by the Old Bridge (or Magothy ) aquifer. The basement rock in Middlesex County consists of basalt, sandstone, and shale of Triassic age. The...Woodbury Clay and Merchantville formations form a confining layer above the Magothy aquifer; the thickness of this confining layer is less than 100 feet

The synthetic human beta-defensin-3 C15 peptide exhibits antimicrobial activity against Streptococcus mutans, both alone and in combination with dental disinfectants.

PubMed

Ahn, Ki Bum; Kim, A Reum; Kum, Kee-Yeon; Yun, Cheol-Heui; Han, Seung Hyun

2017-10-01

Streptococcus mutans is a major etiologic agent of human dental caries that forms biofilms on hard tissues in the human oral cavity, such as tooth and dentinal surfaces. Human β-defensin-3 (HBD3) is a 45-amino-acid natural antimicrobial peptide that has broad spectrum antimicrobial activity against bacteria and fungi. A synthetic peptide consisting of the C-terminal 15 amino acids of HBD3 (HBD3-C15) was recently shown to be sufficient for its antimicrobial activity. Thus, clinical applications of this peptide have garnered attention. In this study, we investigated whether HBD3-C15 inhibits the growth of the representative cariogenic pathogen Streptococcus mutans and its biofilm formation. HBD3-C15 inhibited bacterial growth, exhibited bactericidal activity, and attenuated bacterial biofilm formation in a dose-dependent manner. HBD3-C15 potentiated the bactericidal and anti-biofilm activity of calcium hydroxide (CH) and chlorhexidine digluconate (CHX), which are representative disinfectants used in dental clinics, against S. mutans. Moreover, HBD3-C15 showed antimicrobial activity by inhibiting biofilm formation by S. mutans and other dentinophilic bacteria such as Enterococcus faecalis and Streptococcus gordonii, which are associated with dental caries and endodontic infection, on human dentin slices. These effects were observed for HBD3-C15 alone and for HBD3-C15 in combination with CH or CHX. Therefore, we suggest that HBD3-C15 is a potential alternative or additive disinfectant that can be used for the treatment of oral infectious diseases, including dental caries and endodontic infections.

Ions-modified nanoparticles affect functional remineralization and energy dissipation through the resin-dentin interface.

PubMed

Toledano, Manuel; Osorio, Raquel; Osorio, Estrella; Medina-Castillo, Antonio Luis; Toledano-Osorio, Manuel; Aguilera, Fátima S

2017-04-01

The aim of this study was to evaluate changes in the mechanical and chemical behavior, and bonding ability at dentin interfaces infiltrated with polymeric nanoparticlesstandard deviations and modes of failure are (NPs) prior to resin application. Dentin surfaces were treated with 37% phosphoric acid followed by application of an ethanol suspension of NPs, Zn-NPs or Ca-NPs followed by the application of an adhesive, Single Bond (SB). Bonded interfaces were stored for 24h, submitted to microtensile bond strength test, and evaluated by scanning electron microscopy. After 24h and 21 d of storage, the whole resin-dentin interface adhesive was evaluated using a Nano-DMA. Complex modulus, storage modulus and tan delta (δ) were assessed. AFM imaging and Raman analysis were performed. Bond strength was not affected by NPs infiltration. After 21 d of storage, tan δ generally decreased at Zn-NPs/resin-dentin interface, and augmented when Ca-NPs or non-doped NPs were used. When both Zn-NPs and Ca-NPs were employed, the storage modulus and complex modulus decreased, though both moduli increased at the adhesive and at peritubular dentin after Zn-NPs infiltration. The phosphate and the carbonate peaks, and carbonate substitution, augmented more at interfaces promoted with Ca-NPs than with Zn-NPs after 21 d of storage, but crystallinity did not differ at created interfaces with both ions-doped NPs. Crosslinking of collagen and the secondary structure of collagen improved with Zn-NPs resin-dentin infiltration. Ca-NPs-resin dentin infiltration produced a favorable dissipation of energy with minimal stress concentration trough the crystalline remineralized resin-dentin interface, causing minor damage at this structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dentin-Composite Bond Strength Measurement Using the Brazilian Disk Test

PubMed Central

Carrera, Carola A.; Chen, Yung-Chung; Li, Yuping; Rudney, Joel; Aparicio, Conrado; Fok, Alex

2016-01-01

Objectives This study presents a variant of the Brazilian disk test (BDT) for assessing the bond strength between composite resins and dentin. Methods Dentin-composite disks (φ 5 mm × 2 mm) were prepared using either Z100 or Z250 (3M ESPE) in combination with one of three adhesives, Adper Easy Bond (EB), Adper Scotchbond Multi-Purpose (MP) and Adper Single Bond (SB), and tested under diametral compression. Acoustic emission (AE) and digital image correlation (DIC) were used to monitor debonding of the composite from the dentin ring. A finite element (FE) model was created to calculate the bond strengths using the failure loads. Fracture modes were examined by scanning electron microscopy (SEM). Results Most specimens fractured along the dentin-resin composite interface. DIC and AE confirmed interfacial debonding immediately before fracture of the dentin ring. Results showed that the mean bond strength with EB (14.9±1.9 MPa) was significantly higher than with MP (13.2±2.4 MPa) or SB (12.9±3.0 MPa) (p<0.05); no significant difference was found between MP and SB (p>0.05). Z100 (14.5±2.3 MPa) showed higher bond strength than Z250 (12.7±2.5 MPa) (p<0.05). Majority of specimens (91.3%) showed an adhesive failure mode. EB failed mostly at the dentin-adhesive interface, whereas MP at the composite-adhesive interface; specimens with SB failed at the composite-adhesive interface and cohesively in the adhesive. Conclusions The BDT variant showed to be a suitable alternative for measuring the bond strength between dentin and composite, with zero premature failure, reduced variability in the measurements, and consistent failure at the dentin-composite interface. PMID:27395367

Influence of various bonding techniques on the fracture strength of thin CAD/CAM-fabricated occlusal glass-ceramic veneers.

PubMed

Yazigi, Christine; Kern, Matthias; Chaar, Mohamed Sad

2017-11-01

To evaluate the efficiency of immediate dentin sealing and the effects of different bonding protocols on the fracture strength of CAD/CAM occlusal veneers bonded to exposed dentin. Ninety-six extracted maxillary premolars were initially divided into three main groups with 32 specimens each: without immediate dentin sealing, immediate dentin sealing/total etching and immediate dentin sealing/selective etching. Teeth were identically prepared in the dentin to receive occlusal veneers of 0.8mm thickness, milled from lithium disilicate ceramic blocks (IPS e.max CAD). Each main group was later subdivided, according to the pre-cementation surface etching protocol (total/selective), into two subgroups with 16 specimens each. All restorations were adhesively bonded using a resin cement (Variolink Esthetic). Half of the specimens of each subgroup were subjected to thermo-dynamic loading in a chewing simulator with 1,200,000 cycles at 10kg load. The other half and the surviving specimens were subjected to quasi-static loading until failure. Statistical analysis was performed using three-way ANOVA and Tukey's post-hoc tests. All specimens except one survived the artificial aging. A significantly higher fracture strength of restorations (p ≤ 0.001) was obtained when immediate dentin sealing was followed regardless of the etching method with values ranging from a minimum of 1122 ± 336N to a maximum of 1853 ± 333N. Neither the pre-cementation treatment nor the artificial aging had a statistical significant effect on the fracture strength. Immediate dentin sealing protocol is recommended whenever dentin is exposed during the preparation for thin glass-ceramic occlusal veneers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Quantitative Evaluation of MDP-Ca Salt and DCPD after Application of an MDP-based One-step Self-etching Adhesive on Enamel and Dentin.

PubMed

Yokota, Yoko; Fujita, Kou Nakajima; Uchida, Ryoichiro; Aida, Etsuko; Aoki, Naoko Tabei; Aida, Masahiro; Nishiyama, Norihiro

To investigate the effects of an experimental 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based one-step self-etching adhesive (EX adhesive) applied to enamel and dentin on the production of calcium salt of MDP (MDP-Ca salt) and dicalcium phosphate dehydrate (DCPD) at various periods. The EX adhesive was prepared. Bovine enamel and dentin reactants were prepared by varying the application period of the EX adhesive: 0.5, 1, 5, 30, 60 and 1440 min. Enamel and dentin reactants were analyzed using x-ray diffraction and solid-state phosphorus-31 nuclear magnetic resonance (31P NMR). Curvefitting analyses of corresponding 31P NMR spectra were performed. Enamel and dentin developed several types of MDP-Ca salts and DCPDs with amorphous and crystalline phases throughout the application period. The predominant molecular species of MDP-Ca salt was determined as the monocalcium salt of the MDP monomer. Dentin showed a faster production rate and greater produced amounts of MDP-Ca salt than did enamel, since enamel showed a knee-point in the production rate of the MDP-Ca salt at the application period of 5 min. In contrast, enamel developed greater amounts of DCPD than did dentin and two types of DCPDs with different crystalline phases at application periods > 30 min. The amounts of MDP-Ca salt developed during the 30-s application of the EX adhesive on enamel and dentin were 7.3 times and 21.2 times greater than DCPD, respectively. The MDP-based one-step adhesive yielded several types of MDP-Ca salts and DCPD with an amorphous phase during the 30-s application period on enamel and dentin.

Dentin bond strength and nanoleakage of the adhesive interface after intracoronal bleaching.

PubMed

Cavalli, Vanessa; Sebold, Maicon; Shinohara, Mirela Sanae; Pereira, Patrícia Nóbrega Rodrigues; Giannini, Marcelo

2018-04-01

This study evaluated dentin bond strength (BS) and nanoleakage of non- and pre-etched dentin immediately (T 0 ,), 7 days (T 7 ), and 14 days (T 14 ) after bleaching. Bovine incisors (150) were selected and half of them submitted to intrapulpal dentin etching (e). Non- and pre-etched dentin were subjected to the following (n = 15): no bleaching/control (C); 35% carbamide peroxide (CP); 35% hydrogen peroxide (35% HP); 25% hydrogen peroxide (25% HP); and sodium perborate (SP). Bleaching agents were applied to the pulp chamber four times within a 72-h interval. Afterwards, pulp chamber dentin was prepared for the BS test at different evaluation times (n = 5): T 0 , T 7 , and T 14 . Composite blocks were built on pulp chamber and sectioned in slices. Slices were reduced to an hour-glass shape with a cross-sectional area of 0.8 mm 2 and submitted to microtensile BS test. Two additional specimens for each group were prepared for nanoleakage evaluation by transmission electron microscopy (TEM). Results were analyzed by ANOVA (two-way) and Dunnett's test (p < .05). BS decreased immediately after intracoronal bleaching for both sound and pre-etched dentin (p < .05). At T 14 , the BS of non-etched bleached dentin increased for all groups, whereas the pre-etched SPe group presented BS similar to the Ce. Nanoleakage within the hybrid layer was perceptible immediately after bleaching, although a decrease in nanoleakage was observed for all groups at T 14 . Adhesive restorations should be performed 7-14 days after bleaching, according to the bleaching agent used. Intracoronal bleaching should be performed preferably with sodium perborate if previous dentin etching is applied. © 2018 Wiley Periodicals, Inc.

Influence of Different Dentin Substrate (Caries-Affected, Caries-Infected, Sound) on Long-Term μTBS.

PubMed

Costa, Ana Rosa; Garcia-Godoy, Franklin; Correr-Sobrinho, Lourenço; Naves, Lucas Zago; Raposo, Luís Henrique Araújo; Carvalho, Fabíola Galbiatti de; Sinhoreti, Mário Alexandre Coelho; Puppin-Rontani, Regina Maria

2017-01-01

The aim of this study was to evaluate the μTBS in different dentin substrates and water-storage periods. Twenty-four dentin blocks obtained from sound third molars were randomly divided into 3 groups: Sound dentin (Sd), Caries-affected dentin (Ca) and Caries-infected dentin (Ci). Dentin blocks from Ca and Ci groups were subjected to artificial caries development (S. mutans biofilm). The softest carious tissue was removed using spherical drills under visual inspection with Caries Detector solution (Ca group). It was considered as Ci (softer and deeply red stained dentin) and Ca (harder and slightly red stained dentin). The Adper Single Bond 2 adhesive system was applied and Z350 composite blocks were built in all groups. Teeth were stored in deionized water for 24 h at 37 ºC and sectioned into beams (1.0 mm2 section area). The beams from each tooth were randomly divided into three storages periods: 24 h, 6 months or 1 year. Specimens were submitted to µTBS using EZ test machine at a crosshead speed of 1.0 mm/min. Failure mode was examined by SEM. Data from µTBS were submitted to split plot two-way ANOVA and Tukey's HSD tests (a=0.05). The µTBS (MPa) of Sd (41.2) was significantly higher than Ca (32.4) and Ci (27.2), regardless of storage. Ca and Ci after 6 months and 1 year, presented similar µTBS. Mixed and adhesive failures predominated in all groups. The highest µTBS values (48.1±9.1) were found for Sd at 24 h storage. Storage of specimens decreased the µTBS values for all conditions.

Combined Antibacterial Effect of Sodium Hypochlorite and Root Canal Sealers against Enterococcus faecalis Biofilms in Dentin Canals.

PubMed

Du, Tianfeng; Wang, Zhejun; Shen, Ya; Ma, Jingzhi; Cao, Yingguang; Haapasalo, Markus

2015-08-01

The present study aimed to evaluate the antibacterial effect of the combined use of sodium hypochlorite (NaOCl) and root canal sealers on Enterococcus faecalis biofilms using a dentin infection model. Cells of E. faecalis were introduced into the dentinal tubules by centrifugation and incubated in brain-heart infusion for 3 weeks. The biofilms in dentin were first subjected to 5% NaOCl or sterile water for 10 minutes followed by an equal thickness of AH Plus (Dentsply International Inc, York, PA), Endosequence BC Sealer (Brasseler USA, Savannah, GA), or MTA Fillapex (Angelus Indústria de Produtos Odontológicos S/A, Londrina, Brazil) placed on the root canal wall of the dentin specimens for 7, 30, and 60 days. Gutta-percha and water were used in a similar manner as controls. The proportions of dead and live bacteria inside the dentinal tubules were assessed by confocal laser scanning microscopy and viability staining. The combined use of NaOCl and sealers (30 and 60 days) killed significantly more bacteria than NaOCl or sealers alone (P < .05). NaOCl + MTA Fillapex was the most effective antibacterial combination by killing 83% bacteria in dentin tubules in 60 days. Thirty and 60 days of exposure to the sealers resulted in significantly more dead bacteria in dentin biofilms than 7-day exposures (P < .05). The placement of root canal sealer after NaOCl treatment enhanced antibacterial effects against E. faecalis in the dentinal tubules. Little additional effect was obtained after 30 days of exposure to sealers. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Effects of acid etching and adhesive treatments on host-derived cysteine cathepsin activity in dentin.

PubMed

Zhang, Wenhao; Yang, Weixiang; Wu, Shuyi; Zheng, Kaibin; Liao, Weili; Chen, Boli; Yao, Ke; Liang, Guobin; Li, Yan

2014-10-01

To analyze the effects of different processes during bonding on endogenous cysteine cathepsin activity in dentin. Dentin powder, prepared from extracted human third molars, was divided into 10 groups. Two lots of dentin powder were used to detect the effects of the procedure of protein extraction on endogenous cathepsin activity. The others were used to study effects of different acid-etching or adhesive treatments on enzyme activity. Concentrations of 37% phosphoric acid or 10% phosphoric acid, two etch-and-rinse adhesive systems, and two self-etching adhesive systems were used as dentin powder treatments. The untreated mineralized dentin powder was set as the control. After treatment, the proteins of each group were extracted. The total cathepsin activity in the extracts of each group was monitored with a fluorescence reader. In the control group, there were no significant differences in cathepsin activity between the protein extract before EDTA treatment and the protein extract after EDTA treatment (p > 0.05). The cathepsin activities of the three different extracts in the 37% phosphoric acid-treated group were different from each other (p < 0.05). The two acid-etching groups and two etch-and-rinse groups showed significant enzyme activity reduction vs the control group (p < 0.05). There were no significant differences between those four groups (p > 0.05). Treating the dentin powder with any of the two self-etching adhesives resulted in an increase in cathepsin activity (p < 0.05). The activity of cysteine cathepsins can be detected in dentin powder. Treatment with EDTA during protein extraction exerted an influence on cathepsin activity. Acid etching or etch-and-rinse adhesive systems may reduce the activity of endogenous cathepsins in dentin. Self-etching adhesive systems may increase the enzyme activity.

Bonding performance of experimental bioactive/biomimetic self-etch adhesives doped with calcium-phosphate fillers and biomimetic analogs of phosphoproteins.

PubMed

Abuna, Gabriel; Feitosa, Victor P; Correr, Americo Bortolazzo; Cama, Giuseppe; Giannini, Marcelo; Sinhoreti, Mario A; Pashley, David H; Sauro, Salvatore

2016-09-01

This study examined the bonding performance and dentin remineralization potential of an experimental adhesive containing calcium-phosphate (Ca/P) micro-fillers, and self-etching primers doped with phosphoprotein biomimetic analogs (polyacrylic acid-(PAA) and/or sodium trimetaphosphate-(TMP)). Experimental self-etching primers doped with biomimetic analogs (PAA and/or TMP), and an adhesive containing Ca(2+), PO4(-3)-releasing micro-fillers (Ca/P) were formulated. Sound human dentin specimens were bonded and cut into sticks after aging (24h or 6 months) under simulated pulpal pressure (20cm H2O), and tested for microtensile bond strength (μTBS). Results were analyzed using two-way ANOVA and Tukey's test (p<0.05). Interfacial silver nanoleakage was assessed using SEM. Remineralization of EDTA-demineralized dentin was assessed through FTIR and TEM ultrastructural analysis. Application of the Ca/P-doped adhesive with or without dentin pre-treatments with the primer containing both biomimetic analogs (PAA and TMP) promoted stable μTBS over 6 months. Conversely, μTBS of the control primer and filler-free adhesive significantly decreased after 6 months. Nanoleakage decreased within the resin-dentin interfaces created using the Ca/P-doped adhesives. EDTA-demineralized dentin specimens treated the Ca/P-doped adhesive and the primer containing PAA and TMP showed phosphate uptake (FTIR analysis), as well as deposition of needle-like crystallites at intrafibrillar level (TEM analysis). The use of Ca/P-doped self-etching adhesives applied in combination with analogs of phosphoproteins provides durable resin-dentin bonds. This approach may represent a suitable bonding strategy for remineralization of intrafibrillar dentin collagen within the resin-dentin interface. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparison of removed dentin thickness with hand and rotary instruments

PubMed Central

Shahriari, Shahriar; Abedi, Hasan; Hashemi, Mahdi; Jalalzadeh, Seyed Mohsen

2009-01-01

INTRODUCTION: The aim of this study was to evaluate the amount of dentine removed after canal preparation using stainless steel (SS) hand instruments or rotary ProFile instruments. MATERIALS AND METHODS: Thirty-six extracted human teeth with root canal curvatures less than 30º were embedded in clear polyester resin. The roots were cut horizontally at apical 2, 4 and 7 mm. Dentin thickness was measured at each section and the sections were accurately reassembled using a muffle. Root canals were randomly prepared by SS hand instruments or rotary ProFile instruments. Root sections were again separated, and the remaining dentin thickness was measured. Mann-Whitney U and t tests were performed for analytic comparison of the results. RESULTS: The thickness of removed dentin was significantly different between the two used methods (P<0.05). Significantly greater amounts of dentin was removed mesially in all sections in hand instrumentation group (P<0.001). CONCLUSION: ProFile rotary instrumentation prepares root canals with a greater conservation of tooth structure. PMID:23940489

Evaluation of the colour change in enamel and dentine promoted by the interaction between 2% chlorhexidine and auxiliary chemical solutions.

PubMed

Souza, Matheus; Cecchin, Doglas; Barbizam, Joao V B; Almeida, José F A; Zaia, Alexandre Augusto; Gomes, Brenda P F A; Ferraz, Caio C R

2013-12-01

To evaluate the colour change in enamel and dentine, promoted by interaction of 2% chlorhexidine gluconate (CHX) with 5.25% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA). Fragments containing enamel and dentine were obtained from the crowns of extracted bovine incisors. Before and after immersion of the samples in the substances, they were evaluated with reference to the colour of the enamel and dentine. The values obtained in numerical scores were subjected to statistical analysis using Wilcoxon test. A colour change in the enamel and dentine in groups treated with CHX gel + NaOCl and CHX gel + NaOCl + EDTA, and a change in colour only in the dentine in groups treated with CHX solution + NaOCl and CHX solution + NaOCl + EDTA. When used prior to NaOCl, CHX has the ability to induce a colour change in dental structures. © 2011 The Authors. Australian Endodontic Journal © 2011 Australian Society of Endodontology.

A Dentin Sialophosphoprotein Mutation That Partially Disrupts a Splice Acceptor Site Causes Type II Dentin Dysplasia

PubMed Central

Lee, Sook-Kyung; Hu, Jan C.-C.; Lee, Kyung-Eun; Simmer, James P.; Kim, Jung-Wook

2009-01-01

The dentin sialophosphoprotein (DSPP) gene on chromosome 4q21.3 encodes the major noncollagenous protein in tooth dentin. DSPP mutations are the principal cause of dentin dysplasia type II, dentinogenesis imperfecta type II, and dentinogenesis imperfecta type III. We have identified a DSPP splice junction mutation (IVS2-6T>G) in a family with dentin dysplasia type II. The primary dentition is discolored brown with severe attrition. The mildly discolored permanent dentition has thistle-shaped pulp chambers, pulp stones, and eventual pulp obliteration. The mutation is in the sixth nucleotide from the end of intron 2, perfectly segregates with the disease phenotype, and is absent in 200 normal control chromosomes. An in vitro splicing assay shows that pre-mRNA splicing of the mutant allele generates wild-type mRNA and mRNA lacking exon 3 in approximately equal amounts. Skipping exon 3 might interfere with signal peptide cleavage, causing endoplasmic reticulum stress, and also reduce DSPP secretion, leading to haploinsufficiency. PMID:19026876

Effects of the bisphosphonate alendronate on molars of young rats after lateral luxation.

PubMed

Rothbarth, Cláudia Pires; Bradaschia-Correa, Vivian; Ferreira, Lorraine Braga; Arana-Chavez, Victor Elias

2014-12-01

The bisphosphonate alendronate (ALN) was employed with the aim of investigating its effects on dental and periodontal tissues after lateral luxation of developing molars. Twenty-one-day-old Wistar rats had their second upper molars laterally luxated. Daily 2.5 mg kg(-1) ALN injections started at the day of the luxation; controls received sterile saline solution. The teeth were analyzed 7, 14, and 21 days after the procedure. On the days cited, the maxillae were fixed, decalcified, and embedded in paraffin or Spurr resin. The paraffin sections were stained with H&E, incubated for TRAP histochemistry or immunolabeled for osteopontin (OPN). Spurr ultrathin sections were examined in a transmission electron microscope. After 21 days, the root apex of luxated molars without ALN was wide open and disorganized and also covered by an irregular layer of cellular cementum, which was not observed in ALN-treated animals. Ankylosis sites were observed in ALN rats in both luxated and non-luxated teeth. The TRAP-positive osteoclasts were more numerous in ALN group, despite their latent ultrastructural appearance without the presence of resorption apparatus compared to controls. OPN immunolabeling revealed a thick immunopositive line in the dentin that must be resultant from the moment of the luxation, while ALN-treated specimens did not present alterations in dentin. The present findings indicate that alendronate inhibits some alterations in dentin and cementum formation induced by dental trauma. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A micro-computed tomographic evaluation of dentinal microcrack alterations during root canal preparation using single-file Ni-Ti systems.

PubMed

Li, Mei-Lin; Liao, Wei-Li; Cai, Hua-Xiong

2018-01-01

The aim of the present study was to evaluate the length of dentinal microcracks observed prior to and following root canal preparation with different single-file nickel-titanium (Ni-Ti) systems using micro-computed tomography (micro-CT) analysis. A total of 80 mesial roots of mandibular first molars presenting with type II Vertucci canal configurations were scanned at an isotropic resolution of 7.4 µm. The samples were randomly assigned into four groups (n=20 per group) according to the system used for root canal preparation, including the WaveOne (WO), OneShape (OS), Reciproc (RE) and control groups. A second micro-CT scan was conducted after the root canals were prepared with size 25 instruments. Pre- and postoperative cross-section images of the roots (n=237,760) were then screened to identify the lengths of the microcracks. The results indicated that the microcrack lengths were notably increased following root canal preparation (P<0.05). The alterations in microcrack length in the OS group were more significant compared with those in the WO, RE and control groups (P<0.05). In conclusion, the formation and development of dentinal microcracks may be associated with the movement caused by preparation rather than the taper of the files. Among the single-file Ni-Ti systems, WO and RE were not observed to cause notable microcracks, while the OS system resulted in evident microcracks.

The NH2-terminal and COOH-terminal fragments of dentin matrix protein 1 (DMP1) localize differently in the compartments of dentin and growth plate of bone.

PubMed

Maciejewska, Izabela; Cowan, Cameron; Svoboda, Kathy; Butler, William T; D'Souza, Rena; Qin, Chunlin

2009-02-01

Multiple studies have shown that dentin matrix protein 1 (DMP1) is essential for bone and dentin mineralization. After post-translational proteolytic cleavage, DMP1 exists within the extracellular matrix of bone and dentin as an NH2-terminal fragment, a COOH-terminal fragment, and the proteoglycan form of the NH2-terminal fragment (DMP1-PG). To begin to assess the biological function of each fragment, we evaluated the distribution of both fragments in the rat tooth and bone using antibodies specific to the NH2-terminal and COOH-terminal regions of DMP1 and confocal microscopy. In rat first molar organs, the NH2-terminal fragment localized to predentin, whereas the COOH-terminal fragment was mainly restricted to mineralized dentin. In the growth plate of bone, the NH2-terminal fragment appeared in the proliferation and hypertrophic zones, whereas the COOH-terminal fragment occupied the ossification zone. Forster resonance energy transfer analysis showed colocalization of both fragments of DMP1 in odontoblasts and predentin, as well as hypertrophic chondrocytes within the growth plates of bone. The biochemical analysis of bovine teeth showed that predentin is rich in DMP1-PG, whereas mineralized dentin primarily contains the COOH-terminal fragment. We conclude that the differential patterns of expression of NH2-terminal and COOH-terminal fragments of DMP1 reflect their potentially distinct roles in the biomineralization of dentin and bone matrices.

Adhesion of resin composite core materials to dentin.

PubMed

O'Keefe, K L; Powers, J M

2001-01-01

This study determined (1) the effect of polymerization mode of resin composite core materials and dental adhesives on the bond strength to dentin, and (2) if dental adhesives perform as well to dentin etched with phosphoric acid as to dentin etched with self-etching primer. Human third molars were sectioned 2 mm from the highest pulp horn and polished. Three core materials (Fluorocore [dual cured], Core Paste [self-cured], and Clearfil Photo Core [light cured]) and two adhesives (Prime & Bond NT Dual Cure and Clearfil SE Bond [light cured]) were bonded to dentin using two dentin etching conditions. After storage, specimens were debonded in microtension and bond strengths were calculated. Scanning electron micrographs of representative bonding interfaces were analyzed. Analysis showed differences among core materials, adhesives, and etching conditions. Among core materials, dual-cured Fluorocore had the highest bond strengths. There were incompatibilities between self-cured Core Paste and Prime & Bond NT in both etched (0 MPa) and nonetched (3.0 MPa) dentin. Among adhesives, in most cases Clearfil SE Bond had higher bond strengths than Prime & Bond NT and bond strengths were higher to self-etched than to phosphoric acid-etched dentin. Scanning electron micrographs did not show a relationship between resin tags and bond strengths. There were incompatibilities between a self-cured core material and a dual-cured adhesive. All other combinations of core materials and adhesives produced strong in vitro bond strengths both in the self-etched and phosphoric acid-etched conditions.

Effect of in vitro chewing and bruxism events on remineralization, at the resin-dentin interface.

PubMed

Toledano, Manuel; Cabello, Inmaculada; Aguilera, Fátima S; Osorio, Estrella; Osorio, Raquel

2015-01-02

The purpose of this study was to evaluate if different in vitro functional and parafunctional habits promote mineralization at the resin-dentin interface after bonding with three different adhesive approaches. Dentin surfaces were subjected to distinct treatments: demineralization by (1) 37% phosphoric acid (PA) followed by application of an etch-and-rinse dentin adhesive, Single Bond (SB) (PA+SB); (2) 0.5 M ethylenediaminetetraacetic acid (EDTA) followed by SB (EDTA+SB); (3) application of a self-etch dentin adhesive, Clearfil SE Bond (SEB). Different loading waveforms were applied: No cycling (I), cycled in sine (II) or square (III) waves, sustained loading hold for 24 h (IV) or sustained loading hold for 72 h (V). Remineralization at the bonded interfaces was assessed by AFM imaging/nano-indentation, Raman spectroscopy and Masson's trichrome staining. In general, in vitro chewing and parafunctional habits, promoted an increase of nano-mechanical properties at the resin-dentin interface. Raman spectroscopy through cluster analysis demonstrated an augmentation of the mineral-matrix ratio in loaded specimens. Trichrome staining reflected a narrow demineralized dentin matrix after loading in all groups except in PA+SB and EDTA+SB samples after sustained loading hold for 72 h, which exhibited a strong degree of mineralization. In vitro mechanical loading, produced during chewing and bruxism (square or hold 24 and 72 h waveforms), induced remineralization at the resin-dentin bonded interface. Copyright © 2014 Elsevier Ltd. All rights reserved.

Microorganism penetration in dentinal tubules of instrumented and retreated root canal walls. In vitro SEM study

PubMed Central

Al-Sulaiman, Alaa; Al-Rasheed, Fellwa; Alnajjar, Fatimah; Al-Abdulwahab, Bander; Al-Badah, Abdulhakeem

2014-01-01

Objectives This in vitro study aimed to investigate the ability of Candida albicans (C. albicans) and Enterococcus faecalis (E. faecalis) to penetrate dentinal tubules of instrumented and retreated root canal surface of split human teeth. Materials and Methods Sixty intact extracted human single-rooted teeth were divided into 4 groups, negative control, positive control without canal instrumentation, instrumented, and retreated. Root canals in the instrumented group were enlarged with endodontic instruments, while root canals in the retreated group were enlarged, filled, and then removed the canal filling materials. The teeth were split longitudinally after canal preparation in 3 groups except the negative control group. The teeth were inoculated with both microorganisms separately and in combination. Teeth specimens were examined by scanning electron microscopy (SEM), and the depth of penetration into the dentinal tubules was assessed using the SMILE view software (JEOL Ltd). Results Penetration of C. albicans and E. faecalis into the dentinal tubules was observed in all 3 groups, although penetration was partially restricted by dentin debris of tubules in the instrumented group and remnants of canal filling materials in the retreated group. In all 3 groups, E. faecalis penetrated deeper into the dentinal tubules by way of cell division than C. albicans which built colonies and penetrated by means of hyphae. Conclusions Microorganisms can easily penetrate dentinal tubules of root canals with different appearance based on the microorganism size and status of dentinal tubules. PMID:25383343

Effect of aging on the microstructure, hardness and chemical composition of dentin.

PubMed

Montoya, C; Arango-Santander, S; Peláez-Vargas, A; Arola, D; Ossa, E A

2015-12-01

Understanding the effects of biological aging on human tissues has been a topic of extensive research. With the increase in healthy seniors and quality of life that topic is becoming increasingly important. In this investigation the effects of aging on the microstructure, chemical composition and hardness of human coronal dentin was studied from a comparison of teeth within "young" and "old" age groups. The microstructure of dentin within three regions (i.e., inner, middle and outer) was analyzed using electron and optical microscopy. The mineral-to-collagen ratio in these three regions was estimated using Raman spectroscopy and the hardness was evaluated using microindentation. Results showed that there were significant differences in tubule density, tubule diameter and peritubular cuff diameter with depth. Although there was no difference in tubule density and diameter of the tubules between the age groups, there was a significant difference in the occlusion ratio. A significant increase in hardness between young and old patients was found for middle and outer dentin. An increase in mineral-to-collagen ratio from inner to outer dentin was also found for both groups. In old patients, an increase in mineral content was found in outer coronal dentin as a consequence of tubule occlusion. An increase in occlusion ratio, hardness, and mineral content was found in the dentin of adult patients with age. This increase is most evident in the outer coronal dentin. Copyright © 2015 Elsevier Ltd. All rights reserved.

The role of glass ionomer cement on the remineralization of infected dentin: an in vivo study.

PubMed

Kuhn, Eunice; Chibinski, Ana Claudia Rodrigues; Reis, Alessandra; Wambier, Denise Stadler

2014-01-01

This study's purpose was to investigate the effect of a glass ionomer cement as a liner over infected unexcavated dentin after 60 days and at 10 to 15 months. Forty-five permanent molars with deep carious lesions were selected. Fragments of carious dentin were removed prior to lining the cavity (baseline sample) with glass ionomer cement (G1) or an inert wax material (G2). Cavities were restored with composite resin and reopened 60 days later, when other fragments were removed (60-day sample). The dentin morphology (scanning electron microscopy) and mineral content of calcium, phosphorus, and fluorine were assessed. During the follow-up periods (60 days and 10 to 15 months), restorations were evaluated and standardized radiographs were taken. A postprocessing routine was used to identify changes in the radiographic density between periods. After 60 days, the dentin exhibited a better organization, fewer bacteria, and signs of remineralization. The weight percents of calcium and phosphorus were higher 60 days after the cavity sealing, regardless of the group. Higher gray levels of carious and sound dentin were seen on the 10- to 15-month radiographs, irrespective of the group. The success rates of G1 and G2 were 89 percent and 88 percent, respectively. The lining material isn't fundamental for caries arrestment. Early (60-day) and late (10 to 15 months) dentin changes occurred, indicating the remineralization of dentin carious tissue.

The Effect of Energy Densities on the Shear Bond Strength of Self-Adhering Flowable Composite to Er:YAG Pretreated Dentin.

PubMed

Nahas, Paul; Zeinoun, Toni; Majzoub, Zeina; Corbani, Karim; Nammour, Samir

2016-01-01

Objective . To investigate the shear bond strength of self-adhering flowable resin composite, to dentin, after exposing it to Er:YAG laser radiation, at different energy densities. Materials and Methods . Sixty freshly extracted human third molars were randomly divided into five groups ( n = 12). In the control group, dentin was left unirradiated, whereas, in the other four groups, dentin was irradiated with Er:YAG laser in noncontact mode (MSP mode = 100  µ s; 10 Hz; beam diameter: 1.3 mm; speed of 1 mm/second; air 6 mL/min; and water 4 mL/min), and respectively, with the following level of energy (50 mJ, 60 mJ, 80 mJ, and 100 mJ). Then, self-adhering flowable resin composite was bonded to all prepared dentin surfaces. Shear bond strength (SBS) was applied and fractured surfaces were examined using scanning electron microscopy. Results . SBS values showed significant differences in 60 mJ ( P < 0.05) compared to other groups. Morphological evaluation revealed tags or plugs in dentinal tubules, especially when 60 mJ and 80 mJ were used. All four groups tended to leave more residues on the dentin surface, than the control group. Conclusion . Er:YAG dentin irradiation may enhance SBS of the self-adhering flowable resin composite when it is used at the appropriate low level of energy density.

The Effect of Energy Densities on the Shear Bond Strength of Self-Adhering Flowable Composite to Er:YAG Pretreated Dentin

PubMed Central

Corbani, Karim

2016-01-01

Objective. To investigate the shear bond strength of self-adhering flowable resin composite, to dentin, after exposing it to Er:YAG laser radiation, at different energy densities. Materials and Methods. Sixty freshly extracted human third molars were randomly divided into five groups (n = 12). In the control group, dentin was left unirradiated, whereas, in the other four groups, dentin was irradiated with Er:YAG laser in noncontact mode (MSP mode = 100 µs; 10 Hz; beam diameter: 1.3 mm; speed of 1 mm/second; air 6 mL/min; and water 4 mL/min), and respectively, with the following level of energy (50 mJ, 60 mJ, 80 mJ, and 100 mJ). Then, self-adhering flowable resin composite was bonded to all prepared dentin surfaces. Shear bond strength (SBS) was applied and fractured surfaces were examined using scanning electron microscopy. Results. SBS values showed significant differences in 60 mJ (P < 0.05) compared to other groups. Morphological evaluation revealed tags or plugs in dentinal tubules, especially when 60 mJ and 80 mJ were used. All four groups tended to leave more residues on the dentin surface, than the control group. Conclusion. Er:YAG dentin irradiation may enhance SBS of the self-adhering flowable resin composite when it is used at the appropriate low level of energy density. PMID:27830151

Effects of different peracetic acid formulations on post space radicular dentin.

PubMed

Belizário, Lauriê Garcia; Kuga, Milton Carlos; Castro-Núñez, Gabriela Mariana; Escalante-Otárola, Wilfredo Gustavo; Só, Marcus Vinicius Reis; Pereira, Jefferson Ricardo

2018-01-05

The optimal irrigating solution with antimicrobial and dentin cleansing properties for post space preparation for fiber posts is unclear. Peracetic acid is one option but is available in various chemical formulations that require evaluation. The purpose of this in vitro study was to evaluate dentin surface cleanliness based on the presence of a smear layer and the number of open dentin tubules. It also investigates the chemical composition of residues after canal irrigation with a 1% peracetic acid solution (PA) at low or high concentration of hydrogen peroxide during the preparation of intracanal fiber posts. After filling the root canals of 40 mandibular incisors, a rotary instrument was used for intracanal preparation to place fiber posts. The teeth were divided into 4 groups (n=10) according to the post space irrigation protocol as follows: CG (control): distilled water; NA (NaOCl): 2.5% sodium hypochlorite; LH: PA with low concentration of hydrogen peroxide; and HH: PA with high concentrations of hydrogen peroxide. After irrigation, the teeth were sectioned, and the intracanal dentin surface was subjected to analysis using energy dispersive spectroscopy to evaluate chemical composition and to scanning electron microscopy (×500) to evaluate the presence of the smear layer. The number of open dentin tubules was measured by scanning electron microscopy analysis (×2000) using photo-editing software. ANOVA and the Tukey test (α=.05) were used to evaluate the data, except for the presence of a smear layer, for which the Kruskal-Wallis and Dunn tests were used (α=.05). The highest concentrations of oxygen in the dentin residues were detected in LH and HH (P<.05); CG and NA showed similar oxygen concentrations (P>.05). NA had a higher concentration of chlorine (P<.05), whereas LH had a lower amount of smear layer and a larger number of open dentin tubules than the other groups (P<.05). These were equivalent to each other (P>.05), except for HH, which also had a larger number of open dentin tubules than CG and NA (P<.05). PA 1% with a low concentration of hydrogen peroxide yielded a lower amount of smear layer and a larger number of open dentin tubules in the dentin of the post space when compared with PA 1% with a high concentration of hydrogen peroxide, despite maintaining a similar oxygen concentration in these dentin residues. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Structure and dynamics of a salt-bridge model system in water and DMSO

NASA Astrophysics Data System (ADS)

Lotze, S.; Bakker, H. J.

2015-06-01

We study the interaction between the ions methylguanidinium and trifluoroacetate dissolved in D2O and dimethylsulfoxide with linear infrared spectroscopy and femtosecond two-dimensional infrared spectroscopy. These ions constitute model systems for the side chains of arginine and glutamic and aspartic acid that are known to form salt bridges in proteins. We find that the salt-bridge formation of methylguanidinium and trifluoroacetate leads to a significant acceleration of the vibrational relaxation dynamics of the antisymmetric COO stretching vibration of the carboxyl moiety of trifluoroacetate. Salt-bridge formation has little effect on the rate of the spectral fluctuations of the CN stretching vibrations of methylguanidinium. The anisotropy of the cross peaks between the antisymmetric COO stretching vibration of trifluoroacetate and the CN stretching vibrations of methylguanidinium reveals that the salt-bridge is preferentially formed in a bidentate end-on configuration in which the two C=O groups of the carboxylate moiety form strong hydrogen bonds with the two -NH2 groups of methylguanidinium.

Tails and bridges in the parabolic restricted three-body problem

NASA Astrophysics Data System (ADS)

Barrabés, Esther; Cors, Josep M.; Garcia-Taberner, Laura; Ollé, Mercè

2017-12-01

After a close encounter of two galaxies, bridges and tails can be seen between or around them. A bridge would be a spiral arm between a galaxy and its companion, whereas a tail would correspond to a long and curving set of debris escaping from the galaxy. The goal of this paper is to present a mechanism, applying techniques of dynamical systems theory, that explains the formation of tails and bridges between galaxies in a simple model, the so-called parabolic restricted three-body problem, i.e. we study the motion of a particle under the gravitational influence of two primaries describing parabolic orbits. The equilibrium points and the final evolutions in this problem are recalled,and we show that the invariant manifolds of the collinear equilibrium points and the ones of the collision manifold explain the formation of bridges and tails. Massive numerical simulations are carried out and their application to recover previous results are also analysed.

Investigation into the Depth of Cure of Resin-Modified Glass-Ionomer Restorative Materials

DTIC Science & Technology

2006-08-01

al?2 studied the acid/base reaction of glass ionomer cements using Raman spectroscopy and confirmed the necessity of water availability for the acid...exchange layer." In the ion-exchange layer, Wilson et al.48 postulated the formation of an ionic bond between the polyacrylic acid and the hydroxyapatite ...investigators further detailed the interaction between the polyalkenoic acids and hydroxyapatite in a later report?’ The bonding of RMGI to dentin was

Two Distinct Processes of Bone-like Tissue Formation by Dental Pulp Cells after Tooth Transplantation

PubMed Central

Yukita, Akira; Yoshiba, Kunihiko; Yoshiba, Nagako; Takahashi, Masafumi; Nakamura, Hiroaki

2012-01-01

Dental pulp is involved in the formation of bone-like tissue in response to external stimuli. However, the origin of osteoblast-like cells constructing this tissue and the mechanism of their induction remain unknown. We therefore evaluated pulp mineralization induced by transplantation of a green fluorescent protein (GFP)–labeled tooth into a GFP-negative hypodermis of host rats. Five days after the transplantation, the upper pulp cavity became necrotic; however, cell-rich hard tissue was observed adjacent to dentin at the root apex. At 10 days, woven bone-like tissue was formed apart from the dentin in the upper pulp. After 20 days, these hard tissues expanded and became histologically similar to bone. GFP immunoreactivity was detected in the hard tissue-forming cells within the root apex as well as in the upper pulp. Furthermore, immunohistochemical observation of α–smooth muscle actin, a marker for undifferentiated cells, showed a positive reaction in cells surrounding this bone-like tissue within the upper pulp but not in those within the root apex. Immunoreactivities of Smad4, Runx2, and Osterix were detected in the hard tissue-forming cells within both areas. These results collectively suggest that the dental pulp contains various types of osteoblast progenitors and that these cells might thus induce bone-like tissue in severely injured pulp. PMID:22899860

Klf10 regulates odontoblast differentiation and mineralization via promoting expression of dentin matrix protein 1 and dentin sialophosphoprotein genes

PubMed Central

Chen, Zhuo; Li, Wentong; Wang, Han; Wan, Chunyan; Luo, Daoshu; Deng, Shuli

2016-01-01

Klf10, a member of the Krüppel-like family of transcription factors, is critical for osteoblast differentiation, bone formation and mineralization. However, whether Klf10 is involved in odontoblastic differentiation and tooth development has not been determined. In this study, we investigate the expression patterns of Klf10 during murine tooth development in vivo and its role in odontoblastic differentiation in vitro. Klf10 protein was expressed in the enamel organ and the underlying mesenchyme, ameloblasts and odontoblasts at early and later stages of murine molar formation. Furthermore, the expression of Klf10, Dmp1, Dspp and Runx2 was significantly elevated during the process of mouse dental papilla mesenchymal differentiation and mineralization. The overexpression of Klf10 induced dental papilla mesenchymal cell differentiation and mineralization as detected by alkaline phosphatase staining and alizarin red S assay. Klf10 additionally up-regulated the expression of odontoblastic differentiation marker genes Dmp1, Dspp and Runx2 in mouse dental papilla mesenchymal cells. The molecular mechanism of Klf10 in controlling Dmp1 and Dspp expression is thus to activate their regulatory regions in a dosage-dependent manner. Our results suggest that Klf10 is involved in tooth development and promotes odontoblastic differentiation via the up-regulation of Dmp1 and Dspp transcription. PMID:26310138

A Model System for Predicting Drug Penetration thru Decayed Dentin into Inflamed Pulps

DTIC Science & Technology

1991-01-09

Proceedings USA Science Conference. HALDI, J. and WYNN, W. (1963): Protein Fractions of the Blood Plasma and Dentinal Pulpal Fluid of the Dog , J Dent Res 42...PASHLEY, D.; KEHL, T.; PASHLEY, E.; and PALMER, P. (19 8 1b): Comparison of In Vitro and In Vivo Dog Dentin Permeability, 3 Dent Res 60(3):763-768. PASHLEY...KEPLER, E.; WILLIAMS and OKABE, A. (1983 ): The Effects of Acid Etching on The In Vivo Permeability of Dentin in the Dog , Archs Oral Biol 28(7):555

Effect of CO2 laser on Class V cavities of human molar teeth under a scanning electron microscope.

PubMed

Watanabe, I; Lopes, R A; Brugnera, A; Katayama, A Y; Gardini, A E

1996-01-01

The purpose of this study was to evaluate the effects of CO2 laser on dentin of class V cavities of extracted human molar teeth using a scanning electron microscope. SEM showed a smooth area with concentric lines formed by melting with subsequent recrystallization of dentin, areas of granulation, vitrified surface, numerous cracks, and irregular areas of descamative dentin. These data indicate that CO2 laser (4 and 6 watts) produces dentin alterations and limit its clinical applications.

Comparison of tensile bond strengths of four one-bottle self-etching adhesive systems with Er:YAG laser-irradiated dentin.

PubMed

Jiang, Qianzhou; Chen, Minle; Ding, Jiangfeng

2013-12-01

This study aimed to investigate the interaction of current one-bottle self-etching adhesives and Er:YAG laser with dentin using a tensile bond strength (TBS) test and scanning electron microscopy (SEM) in vitro. Two hundred and thirteen dentin discs were randomly distributed to the Control Group using bur cutting and to the Laser Group using an Er:YAG laser (200 mJ, VSP, 20 Hz). The following adhesives were investigated: one two-step total-etch adhesive [Prime & Bond NT (Dentsply)] and four one-step self-etch adhesives [G-Bond plus (GC), XENO V (Dentsply), iBond Self Etch (Heraeus) and Adper Easy One (3 M ESPE)]. Samples were restored with composite resin, and after 24-hour storage in distilled water, subjected to the TBS test. For morphological analysis, 12 dentin specimens were prepared for SEM. No significant differences were found between the control group and laser group (p = 0.899); dentin subjected to Prime & Bond NT, XENOV and Adper Easy One produced higher TBS. In conclusion, this study indicates that Er:YAG laser-prepared dentin can perform as well as bur on TBS, and some of the one-step one-bottle adhesives are comparable to the total-etch adhesives in TBS on dentin.

Characterization of Interfacial Chemistry of Adhesive/Dentin Bond Using FTIR Chemical Imaging With Univariate and Multivariate Data Processing

PubMed Central

Wang, Yong; Yao, Xiaomei; Parthasarathy, Ranganathan

2008-01-01

Fourier transform infrared (FTIR) chemical imaging can be used to investigate molecular chemical features of the adhesive/dentin interfaces. However, the information is not straightforward, and is not easily extracted. The objective of this study was to use multivariate analysis methods, principal component analysis and fuzzy c-means clustering, to analyze spectral data in comparison with univariate analysis. The spectral imaging data collected from both the adhesive/healthy dentin and adhesive/caries-affected dentin specimens were used and compared. The univariate statistical methods such as mapping of intensities of specific functional group do not always accurately identify functional group locations and concentrations due to more or less band overlapping in adhesive and dentin. Apart from the ease with which information can be extracted, multivariate methods highlight subtle and often important changes in the spectra that are difficult to observe using univariate methods. The results showed that the multivariate methods gave more satisfactory, interpretable results than univariate methods and were conclusive in showing that they can discriminate and classify differences between healthy dentin and caries-affected dentin within the interfacial regions. It is demonstrated that the multivariate FTIR imaging approaches can be used in the rapid characterization of heterogeneous, complex structure. PMID:18980198

Assessment of resin-dentin interfacial morphology of two ethanol-based universal adhesives: A scanning electron microscopy study

PubMed Central

Awad, Mohamed Moustafa

2017-01-01

Objective: The objective of this study was to assess the resin-dentin interfacial morphology created by two universal adhesives using scanning electron microscopy (SEM). Materials and Methods: The occlusal surfaces of ten (n = 5) molars were reduced to expose a flat surface of dentin. Two universal adhesives, Scotchbond Universal Adhesive and Tetric N-Bond Universal, were independently applied to air-dried dentin. Light-cured resin-based composite restorative materials were used to incrementally build a composite “buildup.” The specimen was sectioned mesiodistally to expose the resin-dentin interface. The inner surfaces of the specimens were polished. Samples were immersed in hydrochloric acid and then rinsed using distilled water. This was followed by immersion of the samples in 1% sodium hypochlorite solution. Then, samples were thoroughly rinsing with distilled water. Dehydration of samples was performed using ascending concentration of ethyl alcohol. Prepared samples were observed SEM at magnifications ×1500 and x4000. Results: Both universal adhesives could penetrate dentin-forming well-defined resin tags, lateral branches as well as a uniform hybrid layer. Conclusions: Two tested universal adhesives applied in self-etch mode can infiltrate into dentin-producing high-quality interfacial morphology. Similar interfacial morphology may be due to the similarity in composition and application mode. PMID:28729794