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Sample records for exposing dentinal tubules

  1. Comparative Morphologic Evaluation and Occluding Effectiveness of Nd: YAG, CO2 and Diode Lasers on Exposed Human Dentinal Tubules: An Invitro SEM Study

    PubMed Central

    Grover, Harpreet Singh; Choudhary, Pankaj

    2016-01-01

    Introduction Dentinal hypersensitivity is one of the most common problem, encountered in dental practice but has least predictable treatment outcome. The advent of lasers in dentistry has provided an additional therapeutic option for treating dentinal hypersensitivity. Although various lasers have been tried over a period of time to treat dentinal hypersensitivity, but still the doubt persist as to which laser leads to maximum dentinal tubular occlusion and is most suitable with minimal hazardous effects. Aim To compare the effects of Nd: YAG, CO2 and 810-nm diode lasers on width of exposed dentinal tubule orifices and to evaluate the morphologic changes on dentinal surface of human tooth after laser irradiation by scanning electron microscope (SEM). Materials and Methods Forty root specimens were obtained from ten freshly extracted human premolars, which were randomly divided into four groups of ten each. Group I: control group treated with only saline, Group II: Nd:YAG laser, Group III: CO2 laser and Group IV: 810-nm diode laser. The specimens were examined using SEM. After calculating mean tubular diameter for each group, the values were compared statistically using parametric one-way ANOVA test and Turkey’s post hoc multiple comparison test. Results All the three lased groups showed a highly statistical significant result with p-value of <0.001 as compared to non-lased group. On intergroup comparison within the lased groups, all the three groups showed statistically significant difference in the reduction of dentinal tubular diameter (p-value < 0.001). Conclusion Nd: YAG laser was found to be most effective, followed by the CO2 laser and 810-nm diode laser was found to be least effective. The morphologic changes like craters, cracks and charring effect of the dentine were seen maximum by the use of CO2 laser. PMID:27630957

  2. Dentin tubule numerical density variations below the CEJ

    PubMed Central

    Komabayashi, T.; Nonomura, G.; Watanabe, L.G.; Marshall, G.W.; Marshall, S.J.

    2008-01-01

    Aim To evaluate dentin tubule numerical density variations below the CEJ. Methodology Three human non-carious permanent canines were sectioned parallel to the CEJ to obtain dentin disks 1 mm thick whose surfaces were 1 mm and 2 mm below the CEJ. Each disk was sectioned into quarters resulting in four segment locations: facial, lingual, mesial, and distal. The outer (PDL side) and inner (pulp side) surfaces of the specimens were shaped to expose dentin with SiC papers and polished. Numerical tubule density was determined from SEM images. All data were statistically analyzed using a three-way ANOVA. Results The dentin tubule density (number/mm2) ranged from 13,700 to 32,300. Dentin tubule density was relatively uniform at 1 and 2 mm below the CEJ and increased by a factor of about two from the outer to the inner surface, which was significantly different (P<0.0001). Conclusions The tubule density variations at the cervical root did not present the marked changes. PMID:18786756

  3. In vivo model for microbial invasion of tooth root dentinal tubules

    PubMed Central

    BRITTAN, Jane L; SPRAGUE, Susan V; MACDONALD, Emma L; LOVE, Robert M; JENKINSON, Howard F; WEST, Nicola X

    2016-01-01

    ABSTRACT Objective Bacterial penetration of dentinal tubules via exposed dentine can lead to root caries and promote infections of the pulp and root canal system. The aim of this work was to develop a new experimental model for studying bacterial invasion of dentinal tubules within the human oral cavity. Material and Methods Sections of human root dentine were mounted into lower oral appliances that were worn by four human subjects for 15 d. Roots were then fixed, sectioned, stained and examined microscopically for evidence of bacterial invasion. Levels of invasion were expressed as Tubule Invasion Factor (TIF). DNA was extracted from root samples, subjected to polymerase chain reaction amplification of 16S rRNA genes, and invading bacteria were identified by comparison of sequences with GenBank database. Results All root dentine samples with patent tubules showed evidence of bacterial cell invasion (TIF value range from 5.7 to 9.0) to depths of 200 mm or more. A spectrum of Gram-positive and Gram-negative cell morphotypes were visualized, and molecular typing identified species of Granulicatella, Streptococcus, Klebsiella, Enterobacter, Acinetobacter, and Pseudomonas as dentinal tubule residents. Conclusion A novel in vivo model is described, which provides for human root dentine to be efficiently infected by oral microorganisms. A range of bacteria were able to initially invade dentinal tubules within exposed dentine. The model will be useful for testing the effectiveness of antiseptics, irrigants, and potential tubule occluding agents in preventing bacterial invasion of dentine. PMID:27119760

  4. Use of Poly (Amidoamine) Dendrimer for Dentinal Tubule Occlusion: A Preliminary Study

    PubMed Central

    Wang, Tianda; Yang, Sheng; Wang, Lei; Feng, Hailan

    2015-01-01

    The occlusion of dentinal tubules is an effective method to alleviate the symptoms caused by dentin hypersensitivity, a significant health problem in dentistry and daily life. The in situ mineralization within dentinal tubules is a promising treatment for dentin hypersensitivity as it induces the formation of mineral on the sensitive regions and occludes the dentinal tubules. This study was carried out to evaluate the in vitro effect of a whole generation poly(amidoamine) (PAMAM) dendrimer (G3.0) on dentinal tubule occlusion by inducing mineralization within dentinal tubules. Dentin discs were treated with PAMAM dendrimers using two methods, followed by the in vitro characterization using Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM) and Energy-Dispersive X-ray Spectroscopy (EDS). These results showed that G3.0 PAMAM dendrimers coated on dentin surface and infiltrated in dentinal tubules could induce hydroxyapatite formation and resulted in effective dentinal tubule occlusion. Moreover, crosslinked PAMAM dendrimers could induce the remineralization of demineralized dentin and thus had the potential in dentinal tubule occlusion. In this in vitro study, dentinal tubules occlusion could be achieved by using PAMAM dendrimers. This could lead to the development of a new therapeutic technique for the treatment of dentin hypersensitivity. PMID:25885090

  5. Effect of depth and tubule direction on ultimate tensile strength of human coronal dentin.

    PubMed

    Inoue, Satoshi; Pereira, Patricia N R; Kawamoto, Chiharu; Nakajima, Masatoshi; Koshiro, Kenichi; Tagami, Junji; Carvalho, Ricardo M; Pashley, David H; Sano, Hidehiko

    2003-03-01

    The purpose of this study was to evaluate the effect of dentin depth and tubule direction on the ultimate tensile strength (UTS) of human dentin. Dentin slabs of 0.5-mm thickness were trimmed either from the mesial and distal (for specimens with the tubules parallel to the tensile force; parallel group) or from the occlusal and pulpal surfaces (perpendicular group) to reduce the cross-sectional area of the superficial, middle, and deep regions to 0.25 mm2, and subjected to microtensile testing. From SEM photomicrographs of the fractured specimens of the parallel group, the tubule density was investigated. For both parallel and perpendicular groups, superficial dentin showed a significantly higher UTS than deep dentin. The tubule density of superficial dentin was significantly lower than that of middle and deep dentin. When performing the microtensile bond test to deep dentin, it is possible that cohesive failure of dentin can occur at relatively low tensile stresses.

  6. Antimicrobial effect of ozonated water on bacteria invading dentinal tubules.

    PubMed

    Nagayoshi, Masato; Kitamura, Chiaki; Fukuizumi, Takaki; Nishihara, Tatsuji; Terashita, Masamichi

    2004-11-01

    Ozone is known to act as a strong antimicrobial agent against bacteria, fungi, and viruses. In the present study, we examined the effect of ozonated water against Enterococcus faecalis and Streptcoccus mutans infections in vitro in bovine dentin. After irrigation with ozonated water, the viability of E. faecalis and S. mutans invading dentinal tubules significantly decreased. Notably, when the specimen was irrigated with sonication, ozonated water had nearly the same antimicrobial activity as 2.5% sodium hypochlorite (NaOCl). We also compared the cytotoxicity against L-929 mouse fibroblasts between ozonated water and NaOCl. The metabolic activity of fibroblasts was high when the cells were treated with ozonated water, whereas that of fibroblasts significantly decreased when the cells were treated with 2.5% NaOCl. These results suggest that ozonated water application may be useful for endodontic therapy.

  7. The effect of dentine location and tubule orientation on the bond strengths between resin and dentine.

    PubMed

    Phrukkanon, S; Burrow, M F; Tyas, M J

    1999-05-01

    This study determined the influence of dentine structure on the micro-tensile bond strengths between resin and dentine of two different dentine adhesive systems (Single Bond, 3M Dental Products, St Paul, MN; MF-102 (experimental self-etching primer), GC Corporation, Tokyo, Japan). The study was separated into two main parts: bond strength measurement and investigation of the bonding interface. Twenty-two human premolars were used for the bond strength measurement. Each tooth was cut vertically, separating the tooth into mesio-distal halves. One half of the tooth was used to bond to a surface perpendicular to the dentinal tubules and other half to bond to a surface parallel to the tubules. For each half, six locations of dentine were bonded. Each material was used in accordance to the manufacturer's directions. Cylindrical hourglass-shaped specimens of 1.2 mm diameter at the bonded interface were manufactured. The bonds were stressed in tension at a crosshead speed of 1 mm/min. Mean bond strengths were compared using LSD, one-way ANOVA, and Student's t-test. The fractured surfaces were examined under a scanning electron microscope, and the frequency of fracture modes was compared using the Kruskal-Wallis and Mann-Whitney U tests. For the investigation of the bonded interface, four teeth were prepared by the same procedure used for the bond test specimens. The bonded interfaces were observed after an acid-base treatment or fracturing across the bonded interface, prior to investigation with a field-emission scanning electron microscope. For Single Bond, the bond strengths for mid-root dentine were significantly lower than for other locations (p < 0.05). For MF-102, there was no significant difference for all locations (p > 0.05). MF-102 bonded well to all locations of dentine while Single Bond showed a porous zone at the base of the hybrid layer. The bonds were not influenced by tubule orientation. The results indicate that the bond for Single Bond may be affected by

  8. Treatment of dentinal tubules by Nd:YAG laser

    NASA Astrophysics Data System (ADS)

    Chmelíčkova, Hana; Zapletalova, Zdeňka; Peřina, Jan, Jr.; Novotný, Radko; Kubínek, Roman; Stranyánek, Martin

    2005-08-01

    Symptom of cervical dentine hypersensitivity attacks from 10% to 15% of population and causes an uncomfortable pain during contact with any matter. Sealing of open dentinal tubules is one of the methods to reach insensibility. Laser as a source of coherent radiation is used to melt dentine surface layers. Melted dentine turns to hard mass with a smooth, non-porous surface. Simulation of this therapy was made in vitro by means of LASAG Nd:YAG pulsed laser system KLS 246-102. Eighty human extracted teeth were cut horizontally to obtain samples from 2 mm to 3 mm thick. First experiments were done on cross section surfaces to find an optimal range of laser parameters. A wide range of energies from 30 mJ to 210 mJ embedded in 0,3 ms long pulse was tested. Motion in X and Y axes was ensured by a CNC driven table and the pulse frequency 15 Hz was chosen to have a suitable overlap of laser spots. Some color agents were examined with the aim to improve surface absorption. Scanning Electron Microscopy was used to evaluate all samples and provided optimal values of energies around 50 J.cm-2. Next experiments were done with the beam oriented perpendicularly to a root surface, close to the real situation. Optical fibers with the diameter of 0,6 mm and 0,2 mm were used to guide a laser beam to teeth surfaces. Laser processing heads with lens F = 100 mm and F = 50 mm were used. The best samples were investigated by means of the Atomic Force Microscopy.

  9. 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

  10. Optical properties of human radicular dentin: ATR-FTIR characterization and dentine tubule direction influence on radicular post adhesion

    NASA Astrophysics Data System (ADS)

    Quinto, Jose; Zamataro, Claudia B.; Benetti, Carolina; Dias, Derly A.; Blay, Alberto; Zezell, Denise Maria

    2015-06-01

    Knowledge of dental structures is essential for understanding of laser interaction and its consequences during adhesion processes. Tubule density in dentin ranges from 4.900 to 90.000 per mm2, for diameters from 1 to 3 μm. Light propagation inside the tubules is associated with tubules orientation. To the best of our knowledge, there is no previous work in literature characterizing physical-chemical alterations in dentin. The dentin samples were irradiated with a Er,Cr:YSGG Laser at wavelength 2.78 μm, with an energy density of 9.46 J/cm2 , above the ablation threshold. ATRFTIR at wavenumbers 2000 to 700 cm-1 was used to evaluate the differences among third root region and tubules orientation.

  11. Resin Adaptation of Radicular Dentin Tubules after Endodontic Instrumentation and Acid Etching.

    DTIC Science & Technology

    1983-02-01

    the manuscript. DISCLAIMERS The statements, opinions, and advertisements in the Journal of Endodontics are solely those of the individual authors...I RD-Ai26 872 RESIN ADAPTATION OF RADICULAR DENTIN TUBULES AFTER / I ENDODONTIC INSTRUMENTATION AND ACID ETCHING(U) WALTER I REED ARMY INST OF...Adaptation to Radicular Dentin Tubules SbisoofpeAfter Endodontic Instrumentation and Acid Etching 1982-1983 6. PERFORMING ORG. REPORTNUMBER -, AUTHOR(a) S

  12. Evaluation of the Diode laser (810nm,980nm) on dentin tubule diameter following internal bleaching

    PubMed Central

    Kiomarsi, Nazanin; Salim, Soheil; Sarraf, Pegah; Javad-Kharazifard, Mohammad

    2016-01-01

    Background The aim of this study was to evaluate the effect of diode laser irradiation and bleaching materials on the dentinal tubule diameter after laser bleaching. Material and Methods The dentin discs of 40 extracted third molar were used in this experiment. Each disc surface was divided into two halves by grooving. Half of samples were laser bleached at different wavelengths with two different concentrations of hydrogen peroxide. Other half of each disc with no laser bleaching remained as a negative control. Dentin discs were assigned randomly into four groups (n=10) with following hydrogen peroxide and diode laser wavelength specifications; Group 1 (30% - 810 nm), group 2 (30% - 980 nm), group 3 (46% - 810 nm) and group 4 (46% - 980 nm). All specimens were sent for scanning electron microscopic (SEM) analysis in order to measure tubular diameter in laser treated and control halves. Data were analyzed by ANOVA and Tukey test (p<0.05). Results A significant reduction in dentin tubule diameter was observed in groups 1, 2 and 4. There was no significant difference between groups 1 and 2 and between groups 3 and 4 after bleaching. Conclusions The SEM results showed that diode laser was able to reduce dentin tubule diameter and its effect on dentin was dependent on chemical action of bleaching material. Key words:Laser, diode, dentin, tubule, diameter. PMID:27398172

  13. 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

  14. Influence of the direction of tubules on bond strength to dentin.

    PubMed

    Ogata, M; Okuda, M; Nakajima, M; Pereira, P N; Sano, H; Tagami, J

    2001-01-01

    This study investigated the influence of the direction of dentinal tubules on resin-dentin tensile bond strength (mu TBS) using four commercially available bonding systems and observed the resin-dentin interfaces with an SEM. The dentin bonding systems used in this study were Clearfil Liner Bond II (LB, Kuraray), Imperva Fluoro Bond (FB, Shofu), Single Bond (SB, 3M) and One-Step (OS, BISCO). Thirty-six extracted caries-free human molars were used for micro tensile bond testing and eight additional teeth were used for scanning electron microscopy (SEM). The teeth were divided into two groups according to the direction of the dentinal tubules at the resin-dentin interface: a perpendicular group, in which the occlusal enamel was removed perpendicular to the long axis of the tooth, and a parallel group, in which the mesial half of the tooth was removed parallel to the long axis of the tooth, and the coronal dentin surface was used for bonding. After the flat dentin surfaces were polished with #600 silicon carbide paper, each surface was treated with one of the four adhesive systems according to the manufacturer's recommendation, then covered with resin composite (Clearfil AP-X, Kuraray) to provide sufficient bulk for micro-tensile bond testing. After 24 hours in 37 degrees C water, the resin-bonded teeth were serially sliced perpendicular to the adhesive surface, the adhesive interface trimmed to a cross sectional area of 1 mm2 and subjected to tensile forces at a crosshead speed of 1 mm/min. Statistical analysis of the tensile bond strengths were performed using two-way ANOVA and Fisher's PLSD test at 95% level of confidence. The tensile bond strength of the group with tubules parallel to the bonded interface was higher than that of tubules cut perpendicularly. This tendency reached statistical significance using SB and OS.

  15. Vitality of Enterococcus faecalis inside dentinal tubules after five root canal disinfection methods

    PubMed Central

    Vatkar, Niranjan Ashok; Hegde, Vivek; Sathe, Sucheta

    2016-01-01

    Aim: To compare the vitality of Enterococcus faecalis within dentinal tubules after subjected to five root canal disinfection methods. Materials and Methods: Dentin blocks (n = 60) were colonized with E. faecalis. After 4 weeks of incubation, the dentin blocks were divided into one control and five test groups (n = 10 each). The root canals of test groups were subjected to one of the disinfection methods, namely, normal saline (NS), sodium hypochlorite (NaOCl), chlorhexidine digluconate (CHX), neodymium-doped yttrium aluminum garnet (Nd: YAG) laser, and diode laser. The effect of disinfection methods was assessed by LIVE/DEAD BacLight stain under the confocal laser scanning microscopy to determine the “zone of dead bacteria” (ZDB). Mean values were calculated for ZDB and the difference between groups was established. Results: Penetration of E. faecalis was seen to a depth of >1000 μm. Viable bacteria were detected with NS irrigation. NaOCl and CHX showed partial ZDB. When the root canals were disinfected with Nd: YAG and diode lasers, no viable bacteria were found. Conclusion: E. faecalis has the ability to colonize inside dentinal tubules to a depth of >1000 μm. In contrast to conventional irrigants, both Nd: YAG and diode lasers were effective in eliminating the vitality of E. faecalis. NS, NaOCl, and CHX showed viable bacteria remaining in dentinal tubules. PMID:27656064

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

    PubMed Central

    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. PMID:26797297

  17. 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.

  18. Piecewise-Constant-Model-Based Interior Tomography Applied to Dentin Tubules

    DOE PAGES

    He, Peng; Wei, Biao; Wang, Steve; ...

    2013-01-01

    Dentin is a hierarchically structured biomineralized composite material, and dentin’s tubules are difficult to study in situ. Nano-CT provides the requisite resolution, but the field of view typically contains only a few tubules. Using a plate-like specimen allows reconstruction of a volume containing specific tubules from a number of truncated projections typically collected over an angular range of about 140°, which is practically accessible. Classical computed tomography (CT) theory cannot exactly reconstruct an object only from truncated projections, needless to say a limited angular range. Recently, interior tomography was developed to reconstruct a region-of-interest (ROI) from truncated data in amore » theoretically exact fashion via the total variation (TV) minimization under the condition that the ROI is piecewise constant. In this paper, we employ a TV minimization interior tomography algorithm to reconstruct interior microstructures in dentin from truncated projections over a limited angular range. Compared to the filtered backprojection (FBP) reconstruction, our reconstruction method reduces noise and suppresses artifacts. Volume rendering confirms the merits of our method in terms of preserving the interior microstructure of the dentin specimen.« less

  19. Ability of three desensitizing agents in dentinal tubule obliteration and durability: An in vitro study

    PubMed Central

    Pathan, Azher Banu; Bolla, Nagesh; Kavuri, Sarath Raj; Sunil, Chukka Ram; Damaraju, Bhargavi; Pattan, Sadhiq Khan

    2016-01-01

    Aim: The purpose of this study was to evaluate the effectiveness of three desensitizing agents on dentinal tubule obliteration and their durability in use on the dentinal tubules. Materials and Methods: Sixty specimens were obtained from 30 extracted sound human maxillary first premolars. Each tooth was mesiodistally sectioned to obtain 30 buccal and 30 lingual surfaces, and enamel was removed in order to simulate hypersensitive dentin. Specimens were divided into four groups with 15 specimens each. Group 1 samples were immersed in artificial saliva, Group 2 samples were coated with Vivasens, Group 3 samples were coated with VOCO Admira Protect, and Group 4 samples were coated with Neo Active Apatite suspension. These specimens were examined under scanning electron microscope (SEM) to find out the occluding ability of the respective products. The specimens were brushed to find out their durability for 1 week and 1 month and were examined under SEM. Statistical Analysis: The results were statistically analyzed by analysis of variance (ANOVA) and Tukey's test. Results: Group 1 differed significantly from the Vivasens, Admira, and Neo Active Apatite groups at 5% level of significance (P < 0.05). The Vivasens group differed significantly from the Admira and Neo Active Apatite groups at 5% level of significance (P < 0.05). Conclusion: The Ormocer-based Admira Protect showed the best results. PMID:26957790

  20. Comparative evaluation of NovaMin desensitizer and Gluma desensitizer on dentinal tubule occlusion: a scanning electron microscopic study

    PubMed Central

    Joshi, Surabhi; Gowda, Ashwini Shivananje

    2013-01-01

    Purpose In this study, the effect of calcium sodium phosphosilicate (NovaMin) desensitizing agent, which is a powder-based system, and hydroxyethyl methacrylate and glutaraldehyde (Gluma desensitizer), which is liquid-based system, on dentinal tubule occlusion was analyzed by scanning electron microscope. The effects of the above two along with one control group were compared to determine the more effective method of sealing the dentinal tubules after initial application. Methods Twenty specimens were allocated to each of 3 groups: Control, Gluma desensitizer, and NovaMin. Two additional samples were also prepared and treated with Gluma and NovaMin; these samples were longitudinally fractured. The specimens were prepared from extracted sound human premolars and were stored in 10% formalin at room temperature. The teeth were cleaned of gross debris and then sectioned to provide one to two dentin specimens. The dentin specimens were etched with 6% citric acid for 2 minutes and rinsed in distilled water. Control discs were dried, and the test discs were treated with the desensitizing agents as per the manufacturer's instructions. The discs as well as longitudinal sections were later analyzed under the scanning electron microscope. The proportions of completely occluded, partially occluded, and open tubules within each group were calculated. The ratios of completely and partially occluded tubules to the total tubules for all the groups was determined, and the data was statistically analyzed using nonparametric tests and statistical significance was calculated. Results NovaMin showed more completely occluded tubules (0.545±0.051) while Gluma desensitizer showed more partially occluded tubules (0.532±0.075). The differences among all the groups were statistically significant (P≤ 0.05). Conclusion Both materials were effective in occluding dentinal tubules but NovaMin appeared more promising in occluding tubules completely after initial application. PMID:24455439

  1. 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

    2017-03-31

    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.

  2. The effects of Pain-Free Desensitizer on dentine permeability and tubule occlusion over time, in vitro.

    PubMed

    Zhang, Y; Agee, K; Pashley, D H; Pashley, E L

    1998-11-01

    The purpose of this in vitro study was to evaluate the efficacy of a new resin emulsion (Pain-Free Desensitizer) treatment for dentine hypersensitivity, for its ability to decrease dentine permeability. Crown segments were prepared from extracted, unerupted human 3rd molars by horizontal sectioning to remove occlusal enamel and the roots. The specimens were allocated in one of two groups: In group 1, the dentine surface was acid-etched to simulate the patent tubules of hypersensitive dentine. In group 2, the mineralized dentine surface was polished free of smear layer using a hydroxyapatite paste and ultrasonication. The hydraulic conductance of each specimen was then measured to obtain a pretreatment of control value. After a single treatment with resin desensitizer, the permeability was remeasured at 5 min, 1 day, 1 week and 1 month. Between measurements, the specimens were stored in buffer solution to simulate the solubilizing effects of saliva. Parallel specimens were followed by SEM examination. The results showed that a single treatment with resin desensitizer produced large, immediate, reductions in dentine permeability in both acid-etched and mineralized surfaces. In the acid-etched (group 1) specimens, the permeability returned to control values within 7 days, while the permeability of the group 2 specimens remained low even after 30 days of soaking. This simple treatment for occluding dentinal tubules may provide sufficient temporary reduction in dentine permeability to permit the development of natural desensitization.

  3. 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

  4. Di-Calcium Phosphate and Phytosphingosine as an Innovative Acid-Resistant Treatment to Occlude Dentine Tubules.

    PubMed

    Sauro, Salvatore; Lin, Ching-Yang; Bikker, Floris J; Cama, Giuseppe; Dubruel, Peter; Soria, José M; D''Onofrio, Alessia; Gillam, David

    The present investigation evaluated the ability of an experimental di-calcium phosphate (DCP) desensitising agent used alone or combined with phytosphingosine (PHS) to occlude dentine tubules and resist a citric acid (CA) or artificial saliva (AS) challenge. Three groups of human dentine specimens (DS) were treated with the following: (1) PHS alone, (2) DCP or (3) a combination of PHS and DCP. Dentine hydraulic conductance of DS was evaluated using a digital flow sensor at 6.9 kPa. The average fluid volume for each of the treated DS was used to calculate the total dentine permeability reduction (%P) prior to and following CA immersion for 1 min or AS immersion for 4 weeks. The treated DS were subjected to both scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy analysis. Statistically significant differences (%P) were identified between the groups by ANOVA and Fisher's multiple comparison test (p < 0.05), respectively. Interestingly, both PHS and DCP appeared to work synergistically. DS treated with DCP or PHS/DCP demonstrated a significant reduction (%P) prior to and following CA or AS challenge (p < 0.05). Both the SEM and FTIR analyses showed consistent brushite crystals occluding the dentine tubules. Conversely, the application of PHS alone failed to demonstrate any significant reduction of dentine permeability (p > 0.05) or show any evidence of occlusion of the dentine tubules. DCP can be used alone or combined with PHS to decrease the dentine permeability as well as to resist a CA and AS challenge. These results would, therefore, suggest that DCP may be a suitable treatment option for dentine hypersensitivity.

  5. The Ability of Triple Antibiotic Paste and Calcium Hydroxide in Disinfection of Dentinal Tubules

    PubMed Central

    Adl, Alireza; Hamedi, Sabie; Sedigh Shams, Mahdi; Motamedifar, Mohamad; Sobhnamayan, Fereshte

    2014-01-01

    Introduction: The purpose of this in vitro study was to compare the ability of triple antibiotic paste (TAP) to calcium hydroxide (CH) in disinfecting dentinal tubules. Material and Methods: Sixty root blocks were obtained from extracted single-rooted human teeth. The root canals were enlarged with Gates-Glidden drills up to size 3 and were contaminated with Enterococcus. faecalis (E. faecalis), and then left for 21 days. The contaminated blocks were treated with saline (as negative control), CH or TAP. Dentin debris was obtained at the end of first and 7th days, using Gates-Glidden drills sizes 4 and 5 from two different depths of 100 and 200 µm. The vital bacterial load was assessed by counting the number of colony forming units (CFUs). The data was analyzed with the Kruskal-Wallis H and Dunn Post-Hoc tests. The Wilcoxon Signed Ranks test was used to check for differences in bacterial growth at both depths (P<0.05). Results: In comparison with CH, the TAP significantly decreased the number of CFUs in both depths and time intervals (P<0.001), while the CH group showed a moderate antibacterial effect. Conclusion: TAP is more effective in disinfecting the canal against E. faecalis compared to CH. PMID:24688581

  6. Effects of Dentifrice Containing Hydroxyapatite on Dentinal Tubule Occlusion and Aqueous Hexavalent Chromium Cations Sorption: A Preliminary Study

    PubMed Central

    Liu, Jing; Hou, Yarong; Zhu, Manqun; Huang, Jiansheng; Xu, Pingping

    2012-01-01

    In order to endow environmental protection features to dentifrice, hydroxyapatite (HA) was added to ordinary dentifrice. The effects on dentinal tubule occlusion and surface mineralization were compared after brushing dentine discs with dentifrice with or without HA. The two types of dentifrice were then added to 100 µg/ml of hexavalent chromium cation (Cr6+) solution in order to evaluate their capacities of adsorbing Cr6+ from water. Our results showed that the dentifrice containing HA was significantly better than the ordinary dentifrice in occluding the dentinal tubules with a plugging rate greater than 90%. Moreover, the effect of the HA dentifrice was persistent and energy-dispersive spectrometer (EDS) revealed that the atomic percentages of calcium and phosphorus on the surface of dentine discs increased significantly. Adding HA to ordinary dentifrice significantly enhanced the ability of dentifrice to adsorb Cr6+ from water with the removal rate up to 52.36%. In addition, the sorption was stable. Our study suggests that HA can be added to ordinary dentifrice to obtain dentifrice that has both relieving dentin hypersensitivity benefits and also helps to control environmental pollution. PMID:23300511

  7. Influence of Ultrasonic Irrigation and Chloroform on Cleanliness of Dentinal Tubules During Endodontic Retreatment-An Invitro SEM Study

    PubMed Central

    Singhal, Anurag; Gurtu, Anuraag; Vinayak, Vineet

    2015-01-01

    Background Ultrasonic irrigation has been proved for its remarkable cleaning efficiency in the field of endodontics. But its role in endodontic re-treatment has been understated. There is not much data available to understand the effect of ultrasonic irrigation for the evaluation of cleanliness of dentinal tubules when it is used with or without chloroform, a gutta percha solvent during endodontic retreatment. Aim To compare the influence of ultrasonic irrigation with syringe irrigation on cleanliness of dentinal tubules after gutta perch removal for endodontic retreatment with or without the use of chloroform a gutta percha solvent using scanning electron microscope (SEM). Materials and Methods Freshly extracted 45 human mandibular premolar teeth for periodontal and orthodontic reasons were taken and were occlusally adjusted to a working length of 19 mm. The root canals of all teeth were prepared chemo mechanically to a master apical file size 40 and were divided in various groups. In Group 1 (n = 5; control group), the canals remained unfilled. In Groups 2 and 3 (n = 20 each), the canals were filled using lateral compaction with gutta-percha and AH plus sealer, removal of root fillings was undertaken after 2 weeks using Gates Glidden drills and H files without chloroform in Group 2 and with chloroform in group 3. The specimen of Group 2 and 3 were further divided into two subgroups I and II (n=10). In subgroup I, irrigation was done using side vented needles and sodium hypochlorite. In subgroup II irrigation was done using passive ultrasonic irrigation with sodium hypochlorite. Thereafter, the roots were split and the sections were observed under SEM. The number of occluded dentinal tubules /total number of dentinal tubules were calculated for the coronal, middle and apical third of each root half. Statistical analysis was performed using one-way ANOVA followed by Tukey’s test using standardized technique. Result Results indicated that the cleanest dentinal

  8. Effect of desensitizing toothpastes on dentin.

    PubMed

    Pinto, Shelon Cristina Souza; Silveira, Camila Maggi Maia; Pochapski, Márcia Thaís; Pilatt, Gibson Luiz; Santos, Fábio André

    2012-01-01

    The objective of this study was to analyze the effects of toothbrushing with desensitizing toothpastes on dentin permeability and dentinal tubule occlusion. Fifty rats provided two hundred incisor teeth divided into five groups: DW, brushed with distilled water (control); FT, brushed with fluoride toothpaste; SCT, brushed with strontium chloride toothpaste; PCT, brushed with potassium citrate toothpaste; and PNT, brushed with potassium nitrate toothpaste. Cavities were prepared to expose the dentinal tubules, and the incisor teeth were brushed using the experimental agents. After each treatment, Evans blue dye solution was applied to the teeth. Dentin permeability was analyzed using scanning electron microscopy and energy-dispersive X-rays (EDX). There were significant differences (p < 0.0001, ANOVA) among the groups regarding dentin permeability, number of dentinal tubules, diameter of dentinal tubules, and opened tubular area. In the SCT, PCT and PNT groups, opened and partially occluded tubules, deposits, and a few smear layers were observed. In the DW and FT groups, most of the dentinal tubules were open, with no deposits or smear layers on the dentin. EDX revealed peaks of calcium and phosphorus in all of the groups, as well as traces of strontium in the SCT group and of potassium in the PCT and PNT groups. Desensitizing toothpaste decreased dentin permeability, although it produced only partial dentin tubule occlusion.

  9. The Effects of CO2 Laser with or without Nanohydroxyapatite Paste in the Occlusion of Dentinal Tubules

    PubMed Central

    Al-maliky, Mohammed Abbood; Mahmood, Ali Shukur; Al-karadaghi, Tamara Sardar; Kurzmann, Christoph; Laky, Markus; Franz, Alexander; Moritz, Andreas

    2014-01-01

    The aim of this study was to evaluate a new treatment modality for the occlusion of dentinal tubules (DTs) via the combination of 10.6 µm carbon dioxide (CO2) laser and nanoparticle hydroxyapatite paste (n-HAp). Forty-six sound human molars were used in the current experiment. Ten of the molars were used to assess the temperature elevation during lasing. Thirty were evaluated for dentinal permeability test, subdivided into 3 groups: the control group (C), laser only (L−), and laser plus n-HAp (L+). Six samples, two per group, were used for surface and cross section morphology, evaluated through scanning electron microscope (SEM). The temperature measurement results showed that the maximum temperature increase was 3.2°C. Morphologically groups (L−) and (L+) presented narrower DTs, and almost a complete occlusion of the dentinal tubules for group (L+) was found. The Kruskal-Wallis nonparametric test for permeability test data showed statistical differences between the groups (P < 0.05). For intergroup comparison all groups were statistically different from each other, with group (L+) showing significant less dye penetration than the control group. We concluded that CO2 laser in moderate power density combined with n-HAp seems to be a good treatment modality for reducing the permeability of dentin. PMID:25386616

  10. Push-out bond strength and dentinal tubule penetration of different root canal sealers used with coated core materials

    PubMed Central

    Purali, Nuhan; Coşgun, Erdal; Calt, Semra

    2016-01-01

    Objectives The aim of this study was to compare the push-out bond strength and dentinal tubule penetration of root canal sealers used with coated core materials and conventional gutta-percha. Materials and Methods A total of 72 single-rooted human mandibular incisors were instrumented with NiTi rotary files with irrigation of 2.5% NaOCl. The smear layer was removed with 17% ethylenediaminetetraacetic acid (EDTA). Specimens were assigned into four groups according to the obturation system: Group 1, EndoRez (Ultradent Product Inc.); Group 2, Activ GP (Brasseler); Group 3, SmartSeal (DFRP Ltd. Villa Farm); Group 4, AH 26 (Dentsply de Trey)/gutta-percha (GP). For push-out bond strength measurement, two horizontal slices were obtained from each specimen (n = 20). To compare dentinal tubule penetration, remaining 32 roots assigned to 4 groups as above were obturated with 0.1% Rhodamine B labeled sealers. One horizontal slice was obtained from the middle third of each specimen (n = 8) and scanned under confocal laser scanning electron microscope. Tubule penetration area, depth, and percentage were measured. Kruskall-Wallis test was used for statistical analysis. Results EndoRez showed significantly lower push-out bond strength than the others (p < 0.05). No significant difference was found amongst the groups in terms of percentage of sealer penetration. SmartSeal showed the least penetration than the others (p < 0.05). Conclusions The bond strength and sealer penetration of resin-and glass ionomer-based sealers used with coated core was not superior to resin-based sealer used with conventional GP. Dentinal tubule penetration has limited effect on bond strength. The use of conventional GP with sealer seems to be sufficient in terms of push-out bond strength. PMID:27200279

  11. Assessment of Photodynamic Therapy (PDT) in Disinfection of Deeper Dentinal Tubules in a Root Canal System: An In Vitro Study

    PubMed Central

    Bhaskar, Dara John; Agali, Chandan R; Punia, Himanshu; Gupta, Vipul; Singh, Vikas; Kadtane, Safalya; Chandra, Sneha

    2014-01-01

    Context: The success of endodontic treatment therapy depends on how well we eliminate pathogenic microflora from the root canal system as micro organism as the major cause of root canal infection. Conventional root canal treatment can fail if microorganisms cannot be removed sufficiently by thorough cleaning, shaping of root canal. Newer modalities such as photodynamic therapy are being tried now a days for disinfection of root canals. Aim & Objectives: The basic aim of this study was assessment of the antimicrobial efficacy of Photodynamic Therapy in deeper dentinal tubules for effective disinfection of root canals using microbiological and scanning electron microscopic examination in vitro. Materials and Methods: The study was conducted at Teerthanker Mahaveer Dental College & Research Centre. The teeth required for study was collected from Department of Oral and Maxillofacial Surgery. Only freshly extracted 20 intact, non carious single rooted teeth which were indicated for orthodontic treatment were taken for this study. Statistical analysis was done using Student’s Unpaired t-test were at (p<0.001) was found to be highly significant. Microbiological examination of samples were done and colony forming units were counted to assess the disinfection potential of photodynamic therapy. Scanning electron microscopic examination of samples was done to check penetration of bacteria’s into deeper dentinal tubules. Results: On examination, there was a marked reduction in microbial growth after use of photodynamic therapy. On scanning electron microscopic examination, it was observed that there were less number of bacteria’s in deeper dentinal tubules in case of PDT group as compared to control group. Conclusion: The results of the present study indicate that PDT can be effectively used during antimicrobial procedures along with conventional disinfection procedure for sterilization of root canals. PMID:25584321

  12. Influence of powder composition and morphology on penetration of gray and white ProRoot mineral trioxide aggregate and calcium hydroxide into dentin tubules

    PubMed Central

    Komabayashi, Takashi; Long, Leann; Ahn, Chul; Spears, Robert; Zhu, Qiang; Eberhart, Robert C.

    2015-01-01

    This study examined the influence of powder composition and morphology on the penetration of Gray and White ProRoot mineral trioxide aggregate (GMTA, WMTA) and calcium hydroxide (CH) into open dentin tubules. GMTA, WMTA, and CH particle dimensions were analyzed by flow particle image analysis (FPIA). Penetration of open dentin tubules into dentin discs was studied by scanning electron microscopy. Five samples of each material were randomly selected and prepared for this study. The GMTA averages for length (μm), width (μm), perimeter (μm), and aspect ratio were 1.94 ± 1.65, 1.43 ± 1.19, 5.61 ± 4.27, and 0.76 ± 0.14, respectively. Corresponding averages for WMTA were 2.04 ± 1.87, 1.49 ± 1.33, 5.88 ± 4.81, and 0.76 ± 0.14, and for CH were 2.26 ± 1.99, 1.62 ± 1.46, 6.70 ± 5.60, and 0.74 ± 0.15, respectively. The rank order of the averages for particle length, width and perimeter from the largest to the smallest material was CH > WMTA > GMTA. The rank order of the averaged aspect ratios was GMTA > WMTA > CH. SEM showed that all three materials, when deposited and agitated on dentin discs, penetrated the open dentin tubules. Tubule occlusion occurred as particle surface concentrations increased. Significant differences in particle length, width, perimeter, and aspect ratio were observed for GMTA, WMTA, and CH (P < 0.0001 in all cases). All particle types penetrated into open tubules when agitated on dentin discs; all tubules were eventually occluded as particle concentrations grew. PMID:25500926

  13. Influence of powder composition and morphology on penetration of Gray and White ProRoot mineral trioxide aggregate and calcium hydroxide into dentin tubules.

    PubMed

    Komabayashi, Takashi; Long, Leann; Ahn, Chul; Spears, Robert; Zhu, Qiang; C Eberhart, Robert

    2014-12-01

    This study examined the influence of powder composition and morphology on the penetration of Gray and White ProRoot mineral trioxide aggregate (GMTA, WMTA) and calcium hydroxide (CH) into open dentin tubules. GMTA, WMTA, and CH particle dimensions were analyzed by flow particle image analysis (FPIA). Penetration of open dentin tubules into dentin discs was studied by scanning electron microscopy. Five samples of each material were randomly selected and prepared for this study. The GMTA averages for length (μm), width (μm), perimeter (μm), and aspect ratio were 1.94 ± 1.65, 1.43 ± 1.19, 5.61 ± 4.27, and 0.76 ± 0.14, respectively. Corresponding averages for WMTA were 2.04 ± 1.87, 1.49 ± 1.33, 5.88 ± 4.81, and 0.76 ± 0.14, and for CH were 2.26 ± 1.99, 1.62 ± 1.46, 6.70 ± 5.60, and 0.74 ± 0.15, respectively. The rank order of the averages for particle length, width and perimeter from the largest to the smallest material was CH > WMTA > GMTA. The rank order of the averaged aspect ratios was GMTA > WMTA > CH. SEM showed that all three materials, when deposited and agitated on dentin discs, penetrated the open dentin tubules. Tubule occlusion occurred as particle surface concentrations increased. Significant differences in particle length, width, perimeter, and aspect ratio were observed for GMTA, WMTA, and CH (P < 0.0001 in all cases). All particle types penetrated into open tubules when agitated on dentin discs; all tubules were eventually occluded as particle concentrations grew. (J Oral Sci 56, 287-293, 2014).

  14. The effects of oxalate-containing products on the exposed dentine surface: an SEM investigation.

    PubMed

    Gillam, D G; Mordan, N J; Sinodinou, A D; Tang, J Y; Knowles, J C; Gibson, I R

    2001-11-01

    In-office products containing oxalates have been claimed to be clinically effective in reducing dentine sensitivity, although there has been limited supporting clinical data. The rationale for their use appears to be based on their potential to act as occluding and/or nerve desensitizing agents. Four commercially available oxalate-containing products were applied to etched dentine discs and the extent of tubule occlusion was observed by scanning electron microscopy. Tenure Quick (aluminium oxalate), Sensodyne Sealant (ferric oxalate) and MS Coat (oxalic acid) covered the dentine surface and occluded the tubules. However, Butler Protect (potassium oxalate) did not cover the surface to any great extent but provided some occlusion. The presence of oxalates after application to glass slides and dentine discs was examined using thin film X-ray diffraction. From samples on glass, only potassium oxalate could be clearly identified (JCPDS 14-0845). No oxalate was detected on dentine discs in either thin film geometry or standard theta two theta mode. We have demonstrated that professionally applied in-office products containing oxalate are capable of covering the dentine surface and/or occluding the tubules to varying degrees. However, X-ray diffraction analysis was unable to confirm the oxalate profile for all products as described in the available commercial literature.

  15. Effect of Nd:YAG Laser Irradiation on the Number of Open Dentinal Tubules and Their Diameter with and without Smear of Graphite: An in Vitro Study

    PubMed Central

    Maleki-pour, Mohammad Reza; Birang, Reza; Khoshayand, Maryam; Naghsh, Narges

    2015-01-01

    Introduction: Dentin hypersensitivity (DH) is characterized by tooth pain arising from exposure of dental roots. In this study the efficiency of neodymium yttrium-aluminum-garnet (Nd:YAG) laser in association with graphite on dentinal surface changes as the alternative to the treatment of DH was evaluated. Methods: Sixteen noncarious human third molars were collected and sectioned into 5 parts from cementoenamel junction (CEJ) to the furcation area. The prepared samples were randomly assigned into five groups (Gs) of each 16: Control (G1), treated by Nd:YAG laser at 0.5 W (G2), irradiation of Nd:YAG with a 0.25 W output power(G3), smeared with graphite and then using Nd:YAG laser at output powers of 0.5 W (G4) and 0.25 W (G5). For all groups the parameters were 15 Hz, 60 s, at two stages and with a right angle irradiation. The number and diameter of dentinal tubules (DT) were compared and analyzed by SPSS software, One way ANOVA and Post hoc LSD tests. Results:The number of open dentinal tubules varied significantly between all groups except among G1 with G3 and G2 with G5. Multiple comparison tests also exhibited significant differences regarding the diameter of tubules between the groups two by two except among G2 with G5. Conclusion: Nd:YAG laser used at 0.25 W and 0.5 W with application of graphite smear was able to reduce the number and diameter of dentinal tubules. PMID:25699166

  16. Dentinal Tubule Disinfection with Propolis & Two Extracts of Azadirachta indica Against Candida albicans Biofilm Formed on Tooth Substrate

    PubMed Central

    Joy Sinha, Dakshita; Garg, Paridhi; Verma, Anurag; Malik, Vibha; Maccune, Edgar Richard; Vasudeva, Agrima

    2015-01-01

    Aim: This study evaluates the disinfection of dentinal tubules using Propolis, Azadirachta indica (alcoholic and aqueous extracts), 2% chlorhexidine gel and calcium hydroxide against Candida albicans biofilm formed on tooth substrate. Materials & Method: One hundred and five human teeth were infected with Candida albicans for 2 days. Samples were divided into 7 groups. Group I- Propolis, Group II- Alcoholic extract of Azadirachta indica, Group III- Aqueous extract of Azadirachta indica, Group IV- 2% Chlorhexidine, Group V- Calcium hydroxide, Group VI- Ethanol and Group VII- Saline (negative control). At the end of 1,3 and 5 days, the antimicrobial efficacy of medicaments against Candida albicans was assessed at the depths of 200 µm and 400 µm. Results: The overall percentage inhibition of fungal growth (at 200 µm and 400 µm depth) was 99.2% with 2% chlorhexidine gel. There was no statistical difference between propolis, alcoholic extract of Azadirachta indica (neem) and 2% chlorhexidine. Conclusion: Propolis and alcoholic extract of Azadirachta indica performed equally well as that of 2% Chlorhexidine. PMID:26962368

  17. Penetration Depth of Sodium Hypochlorite in Dentinal Tubules after Conventional Irrigation, Passive Ultrasonic Agitation and Nd:YAG Laser Activated Irrigation

    PubMed Central

    Ghorbanzadeh, Abdollah; Aminsobhani, Mohsen; Sohrabi, Khosro; Chiniforush, Nasim; Ghafari, Sarvenaz; Shamshiri, Ahmad Reza; Noroozi, Niusha

    2016-01-01

    Introduction: The penetration depth of irrigating solutions in dentinal tubules is limited; consequently, bacteria can remain inside dentinal tubules after the cleaning and shaping of the root canal system. Therefore, new irrigation systems are required to increase the penetration depth of irrigating solutions in dentinal tubules. Methods: A comparative study regarding the penetration depth of sodium hypochlorite (NaOCl) solution in dentinal tubules using four methods, (1) conventional irrigation (CI), (2) smear layer removal plus conventional irrigation (gold standard), (3) passive ultrasonic agitation (PUA) and (4) Nd:YAG laser activated irrigation (LAI), took place on 144 extracted mandibular teeth with a single root canal. After decoronation with a diamond disc and working length determination, the apical foramen was sealed with wax. The canals were prepared up to #35 Mtwo rotary file and 5.25% NaOCl was used for irrigation during preparation. To study the penetration depth of NaOCl, smear layer was eliminated in all samples. Dentinal tubules were stained with crystal violet and after longitudinal sectioning of teeth, the two halves were reassembled and root canal preparation was performed up to #40 Mtwo rotary file. Then the samples were distributed into four experimental groups. Depth of the bleached zone was evaluated by stereomicroscope (20X). Data were analyzed by Kruskal-Wallis test. Results: The highest and lowest average for NaOCl penetration depth in all three coronal, middle and apical sections belonged to CI + smear layer removal and CI. A statistically significant difference was seen when comparing the penetration depth of CI + smear layer removal group to CI and PUA groups in coronal and middle third, in which the average NaOCl penetration depth of the gold standard group was higher (P < 0.05). A statistically significant difference was seen between CI + smear layer removal group and the other three groups including CI, PUA and LAI in apical third

  18. Micromorphological Evaluation of Dentin Treated with Different Desensitizing Agents

    PubMed Central

    Osmari, Deise; de Oliveira Ferreira, Ana Carolina; de Carlo Bello, Mariana; Henrique Susin, Alexandre; Cecília Correa Aranha, Ana; Marquezan, Marcela; Lopes da Silveira, Bruno

    2013-01-01

    Introduction: The purpose of a desensitizing agent is a permanent coating or filling of dentin surface. Morphological analysis in vitro of this treated surface is essential to understand the interaction between desensitizing agent and hypersensitive dentin. The aim was to evaluate the morphology of four dentin surface treated with desensitizing agents. Methods: This was an in vitro laboratory study, where fifteen specimens from extracted human premolars were obtained. The enamel was removed to expose the dentin surface, polished with silicon carbide abrasive papers and etched with 6% citric acid for 2 min.The specimens were randomly divided into 5 groups: G1 - without treatment (control) (C), G2 - fluoride varnish (FV), G3 - potassium oxalate (PO), G4 - 2-step self-etching adhesive system (AS), G5 - diode laser (DL). The specimens were cleaved in the lingual buccaldirection, prepared for analysis by Scanning Electron Microscope and the surface and interior of the dentinal tubules were observed at 1500× magnification. Results: In the control group, the dentin etching promoted smear layer removal and exposure of dentinal tubules. In the group of fluoride varnish, a film was observed on the surface, with plugs of varnish into tubules. In the group of oxalate, partial obliteration of the tubular entrances was observed. In the group of the adhesive system, the tubules were obstructed through the formation of hybrid layer and a physical barrier on the surface. In the group of the diode laser, dentin melting and solidification with partial occlusion of dentinal tubules were observed. Conclusions: All desensitizing agents evaluated demonstrated ability to modify the surface of dentin, with partial or total occlusion of dentinal tubules. Thus, it is suggested to do more clinical studies to verify the effectiveness of the findings. PMID:25606322

  19. Evaluation of dentinal tubule occlusion and depth of penetration of nano-hydroxyapatite derived from chicken eggshell powder with and without addition of sodium fluoride: An in vitro study

    PubMed Central

    Kunam, Divya; Manimaran, Sujatha; Sampath, Vidhya; Sekar, Mahalaxmi

    2016-01-01

    Aim: This in vitro study evaluated the degree of dentinal tubule occlusion and depth of penetration of nano-hydroxyapatite (nHAp) derived from chicken eggshell powder with and without the addition of 2% sodium fluoride (NaF) using scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM). Materials and Methods: nHAp was synthesized and characterized using X-ray diffraction and SEM-energy dispersive spectroscopy. Dentin discs were obtained from extracted teeth, pretreated with 17% ethylenediaminetetraacetic acid for 5 min and were divided into four groups based on the experimental agents as follows: Group 1: Untreated (control), Group 2: 2% NaF, Group 3: nHAp, Group 4: Combination of nHAp and 2% NaF. The treatment protocol was carried out for 7 days, after which the specimens were viewed under SEM and CLSM. Statistical Analysis Used: One-way ANOVA and Tukey's post hoc multiple comparison tests (P < 0.05). Results: All the experimental agents occluded the dentinal tubules, but to varying degrees and depths. Specimens treated with the combination of nHAp and 2% NaF showed complete dentinal tubular occlusion and significantly greater depth of penetration than those treated with nHAp and 2% NaF alone. Conclusion: The combination of nHAp and 2% NaF was the most effective in occluding dentinal tubules. PMID:27217637

  20. In vitro evaluation of dentinal hydraulic conductance and tubule sealing by a novel calcium-phosphate desensitizer.

    PubMed

    Thanatvarakorn, Ornnicha; Nakashima, Syozi; Sadr, Alireza; Prasansuttiporn, Taweesak; Ikeda, Masaomi; Tagami, Junji

    2013-02-01

    In the current trend of materials used for dentin hypersensitivity treatment, calcium-phosphate-containing desensitizers are expected to have advantages in oral environment. A newly formulated desensitizer containing tetracalcium phosphate and dicalcium phosphate anhydrous (CPD-100) was evaluated in comparison to oxalate containing desensitizer (SS) regarding permeability reduction (PR%) by measuring hydraulic conductance on the etched dentin discs in vitro. CPD-100 exhibited mean PR% of 91%, which significantly increased to 98% after immersion in artificial saliva (AS) for 4 weeks (p < 0.001), while SS showed a significant decrease from 99% to 93% (p < 0.01). SEM observation showed newly formed crystallites on CPD-100 treated dentin, which did not exist in SS treated dentin after AS immersion, suggesting that calcium oxalate inhibited formation of new calcium-phosphate minerals. Five-minute acid challenge did not significantly affect PR% of dentin treated by any of the desensitizers. The energy dispersive X-ray spectroscopy (EDS) analysis indicated that the formed layer of CPD-100 were minerals with similar Ca/P ratio to hydroxyapatite. In conclusion, the newly developed calcium-phosphate desensitizer has the potential to exhibit long-term stability in the oral environment, owing to its chemical properties that promote the crystal growth in salivary fluid.

  1. Dentinal tubule disinfection with 2% chlorhexidine, garlic extract, and calcium hydroxide against Enterococcus faecalis by using real-time polymerase chain reaction: In vitro study

    PubMed Central

    Eswar, Kandaswamy; Venkateshbabu, Nagendrababu; Rajeswari, Kalaiselvam; Kandaswamy, Deivanayagam

    2013-01-01

    Aim: To compare the efficacy of garlic extract with 2% chlorhexidine (CHX) and calcium hydroxide Ca(OH)2 in disinfection of dentinal tubules contaminated with Enterococcus faecalis by using real-time polymerase chain reaction (PCR). Materials and Methods: Agar diffusion test was done to evaluate the minimum inhibitory concentration of garlic extract against E. faecalis. Forty human extracted mandibular premolar teeth were selected for this study, access cavity was prepared and cleaning and shaping was done. Middle third of the root was cut using a rotary diamond disc. The teeth specimens were inoculated with E. faecalis for 21 days. Specimens were divided into four groups---Group 1: 2% CHX, Group 2: Garlic extract, Group 3: Ca(OH)2, and Group 4: Saline (negative control). The intracanal medicaments were packed inside the tooth specimens and incubated for 5 days. The dentinal chips were collected at 400 μm depth using a Gates-Glidden drill, following which DNA isolation was done. The specimens were analyzed using real-time PCR. The results were then statistically analyzed using one-way analysis of variance, followed by post hoc Tukey's honestly significant difference (HSD) multiple comparison of means. Results: Threshold cycle (Ct) values of 2% CHX was found to be 32.4, garlic extract to be 27.5, and Ca(OH)2 to be 25.6. Conclusion: A total of 2% CHX showed the maximum efficacy against E. faecalis, followed by garlic extract and Ca(OH)2. PMID:23833449

  2. In vitro antimicrobial activity of sodium hypochlorite, chlorhexidine gluconate and octenidine dihydrochloride in elimination of microorganisms within dentinal tubules of primary and permanent teeth.

    PubMed

    Tirali, Resmiye-Ebru; Bodur, Haluk; Ece, Gülden

    2012-05-01

    The aim of this study was to evaluate the effectiveness of different irrigation solutions at different time intervals for the elimination of E. faecalis and C. albicans penetrated into the dentine tubules of primary and permanent teeth in vitro. The 4 mm primary and permanent teeth sections were sterilized and contaminated with a mixture of E. faecalis and C. albicans strains. After the application of different irrigation solutions (Sodium hypochlorite, Chlorhexidine gluconate, Octenidine Dihydrochloride, saline) to the contaminated tooth sections according to study groups, neutralizers were applied for inactivation of the solutions after 30 sec, 1 min and 5 min. Dentine shavings were placed into TSB and 10 µL from each tube was inoculated on agar plates, followed by an incubation period of 24 h at 37°C. The colonies were counted macroscopically. The results were compared by using Kruskal-Wallis and Mann Whitney U tests, with a significance level at p<0.05. Among the irrigation solutions that were tested against E. faecalis on primary and permanent teeth, the most effective one was found as 5-minute application of 0.1% Octenidine Dihydrochloride. The antibacterial effects of the tested solutions on the same time periods against C. albicans revealed no significant difference. There were no statistically significant differences between primary and permanent teeth with respect to the antimicrobial activity of the tested solutions. Moreover, Octenidine Dihydrochloride may be used as an alternative endodontic irrigant.

  3. The role of toothpaste in the aetiology and treatment of dentine hypersensitivity.

    PubMed

    Addy, M; West, N X

    2013-01-01

    Dentine hypersensitivity (DH) is a common, painful dental condition with a multi-factorial aetiology. The hydrodynamic mechanism theory to explain dentine sensitivity also appears to fit DH: lesions exhibiting large numbers of open dentinal tubules at the surface and patent to the pulp. By definition, DH can only occur when dentine becomes exposed (lesion localisation) and tubules opened (lesion initiation), thus permitting increased fluid flow in tubules on stimulation. Erosion, particularly from dietary acids appears to play a dominant role in both processes. Toothbrushing with most toothpaste products alone cause clinically insignificant wear of enamel but are additive, even synergistic, to erosive enamel loss. Additionally, toothbrushing with toothpaste is implicated in 'healthy' gingival recession. Toothbrushing with most toothpastes removes the smear layer to expose tubules and again can exacerbate erosive loss of dentine. These findings thereby implicate toothbrushing with toothpaste in the aetiology of DH. Management of the condition should have secondary prevention at the core of treatment and therefore, must consider first and foremost the aetiology. Fluoride toothpaste at present appears to provide little primary or secondary preventive benefits to DH; additional ingredients can provide therapeutic benefits. Potassium-based products to block pulpal nerve response have caused much debate and are considered by many as unproven, which should not translate to ineffective. Several toothpaste technologies formulated to block tubules are from studies in vitro, in situ and controlled clinical trials considered proven for the treatment of DH.

  4. The effects of desensitizing agents on the hydraulic conductance of human dentin in vitro.

    PubMed

    Greenhill, J D; Pashley, D H

    1981-03-01

    The hydrodynamic theory of dentin sensitivity states that a stimulus applied at the orifice of exposed dentinal tubules causes movement of tubular fluid which stimulates nerve receptors. The fluid should obey principles of fluid movement through capillary tubes. Any decrease in the functional radius of the dentinal tubules should greatly reduce the rate of fluid flow, thus reducing dentinal sensitivity. The purpose of this study was to evaluate the ability of agents that have been used previously for clinical dentin desensitization to reduce the rate of fluid flow through dentin in vitro. Dentin discs prepared from extracted human third molars were treated with 50% citric acid to remove debris from tubular orifices. After placing the discs in a split chamber device, the rate at which buffer solution could filter across the dentin under 240 cm of water pressure was measured. The occlusal side of the disc was then treated with an agent thought to desensitize dentin to determine if it reduced fluid flow rate. Discs that had more than a 50% reduction in flow rate were examined by scanning electron microscopy to determine if those agents that decreased fluid flow also partially occluded tubular orifices. This in vitro model provided a useful quantitative method for screening a host of preparations that have been used in the past to decrease dentin sensitivity.

  5. Ternary phase diagram of model dentin adhesive exposed to over-wet environments.

    PubMed

    Ye, Q; Park, J; Laurence, J S; Parthasarathy, R; Misra, A; Spencer, P

    2011-12-01

    When adhesives and/or composites are bonded to the tooth, water in the environment can interfere with proper interface formation. Formation of water blisters and phase separation at the adhesive/dentin interface have appeared as new types of bond defects. To better understand this problem, we determined the near-equilibrium partition of the hydrophobic/hydrophilic components when exposed to over-wet environments. Model methacrylate-based adhesives were mixed with different amounts of water to yield well-separated aqueous and resin phases. It was found that less than 0.1% BisGMA but nearly one-third of the HEMA diffused into the aqueous phase, leaving the remaining resin phase relatively hydrophobic. A partial phase diagram was created for the ternary BisGMA/HEMA/water system. All the experimental phase partitioning data were plotted, and the points lay on a binodal curve that separated the single-phase region from the two-phase region. We obtained the 3 tie lines by connecting the 2 points of each conjugate pair of the phase partitioning data from the 3 sets of tripartite mixtures. Information about solubility, water miscibility, distribution ratio, and phase partitioning behavior could be obtained quantitatively. This type of phase diagram will provide a more thorough understanding of current adhesive performance and elucidate directions for further improvement.

  6. Permeability of dentin to adhesive agents.

    PubMed

    Pashley, D H; Ciucchi, B; Sano, H; Horner, J A

    1993-09-01

    The permeability of dentin to adhesive agents is of crucial importance in obtaining good dentinal bonding. In those systems that remove the smear layer, the opportunity exists for resin to infiltrate both tubules and intertubular dentin. Resin penetration into tubules can effectively seal the tubules and can contribute to bond strength if the resin bonds to the tubule wall. Resin infiltration into intertubular dentin can only occur if the mineral phase of dentin is removed by acidic conditioners or chelators. This is more easily accomplished in fractured dentin than in smear layer-covered dentin because of the residual collagen debris that remains on the surface following acid etching of smear layers. The channels for resin infiltration are the perifibrillar spaces created around the collagen fibers of dentin following removal of apatite mineral by acids. The diffusion of adhesive resins through these narrow, tortuous, long channels in 1 to 2 minutes offers a number of challenges that require further research.

  7. Dentin permeability: determinants of hydraulic conductance.

    PubMed

    Reeder, O W; Walton, R E; Livingston, M J; Pashley, D H

    1978-02-01

    A technique is described which permits measurements of the ease with which fluid permeates dentin. This value, the hydraulic conductance of dentin, increased as surface area increases and/or as dentin thickness decreases. It increased 32-fold when dentin was acid etched due to removal of surface debris occluding the tubules.

  8. 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.

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

    PubMed Central

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

    2017-01-01

    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. PMID:28167823

  10. Ultrastructural evaluation of radicular dentin after Nd:YAG laser irradiation combined with different chemical substances.

    PubMed

    Faria, Maria Isabel Anastacio; Souza-Gabriel, Aline Evangelista; Marchesan, Melissa Andreia; Sousa-Neto, Manoel Damiao; Silva-Sousa, Yara Teresinha Correa

    2008-01-01

    This aticle sought to evaluate the dentin morphology after irradiation by a Neodymium:Yttrium-Aluminum-Garnet (Nd:YAG) laser, using different chemical substances to irrigate radicular canals: distilled water, 17% ethylenediaminetetraacetic acid plus Cetavlon (EDTAC), 1% sodium hypochlorite, and 2% chlorhexidine. Groups were subdivided according to the protocol of laser application (n=9). The specimens were analyzed by scanning electron microscopy (SEM). No differences were found in dentin morphology when different root thirds were examined. Regardless of the chemical substance used, alterations were more evident in groups in which the surfaces were dried before laser irradiation. Fusion areas, craters, carbonization, and partially exposed tubules were verified. When the irradiation was performed in water, the smear layer was incorporated into the laser-modified surface. Among the specimens irrigated with EDTAC and laser-treated, partial obliteration of dentin tubules due to the laser action was verified; in addition, there was no remaining smear layer on the surfaces. Samples irrigated with sodium hypochlorite followed by laser irradiation demonstrated similar morphology to the samples in the chlorhexidine group, with some fusion areas present and no exposed dentin tubules or fissures. The irradiation from an Nd:YAG laser in the presence of EDTAC solution provided a more favorable surface pattern compared to the other experimental conditions, due to the removal of the contaminated layer and the posterior sealing of dentin tubules.

  11. Evaluation of the Morphological Characteristics of Laser-Irradiated Dentin

    PubMed Central

    Lilaj, Bledar; Franz, Alexander; Degendorfer, Daniela; Moritz, Andreas

    2015-01-01

    Abstract Objective: The aim of this study was to investigate the effect of different energy settings of Er:YAG laser irradiation on dentin surface morphology with respect to the number of opened dentinal tubules. Background data: An ideally prepared dentin surface with opened dentinal tubules is a prerequisite for adhesive fixation. No study, however, has yet compared the numbers of opened dentinal tubules with regard to statistical differences. Methods: Conventional preparations using a bur with or without additional acid etching acted as control groups. Dentin specimens were prepared from human third molars and randomly divided into eight groups according to the energy settings of the laser (1, 1.5, 4, 6, 7.5, and 8 W) and two controls (bur and bur plus acid etching). After surface preparation, dentin surfaces were analyzed with a scanning electron microscope, and the number of opened dentinal tubules in a defined area was counted. Results: The control groups showed smooth surfaces with (bur plus acid etching) and without opened dentinal tubules (bur), whereas all laser-irradiated surfaces showed rough surfaces. Using the energy setting of 4 W resulted in significantly more opened dentinal tubules than the conventional preparation technique using the bur with additional acid etching. In contrast, the energy setting of 8 W showed significantly fewer opened dentinal tubules, and also exhibited signs of thermal damage. Conclusions: The Er:YAG laser with an energy setting of 4 W generates a dentin surface with opened dentinal tubules, a prerequisite for adhesive fixation. PMID:26389986

  12. Cellular responses in the Malpighian tubules of Scaptotrigona postica (Latreille, 1807) exposed to low doses of fipronil and boric acid.

    PubMed

    Ferreira, Rafael Alexandre Costa; Silva Zacarin, Elaine Cristina Mathias; Malaspina, Osmar; Bueno, Odair Correa; Tomotake, Maria Eliza Miyoko; Pereira, Andrigo Monroe

    2013-03-01

    Studies of sub-lethal effects of pesticide residues on stingless bees are scarce and morphological analysis of organs would add information to toxicological analysis in order to clarify the continuous exposure of Scaptotrigona postica to insecticides. The aim of this study was to evaluate the morphology and histochemistry of the Malpighian tubules (excretory organ) of S. postica exposed to fipronil or boric acid to detect cellular responses that indicate toxicity or adaptative mechanisms to stress induced by exposure of worker bees to low doses of these chemical compounds. Newly emerged bees were submitted to toxicological bioassays and morphological analyses by optical microscopy and Transmission Electron Microscopy, as well as histochemical methods, were performed to detect proteins and glycoconjugates. Additionally, immunohistochemical detection of DNA fragmentation and HSP70 (70-kDa Heat shock protein) were performed to detect cell death and stress response, respectively. Statistical analysis, for the bioassays conducted with ingestion of contaminated diet with boric acid at 0.75% (w/w) or with fipronil at 0.1μg/kg of food, showed that the survival of bees that ingested the contaminated diets were significantly different to the survival rate presented by the control group (P<0.0001). Although some characteristics indicative of initiation of cell death were observed, the cells remained metabolically active in the processes of excretion and inactivation of chemical compounds. The data from this study reinforce the importance of research on sublethal effects of low doses of pesticides on bees in an attempt to assess a possible realistic dose and evaluate the risk assessment of stingless bee S. postica foraging in the vicinity of cultivated fields and/or in green urban areas.

  13. A Mechanistic study of Plasma Treatment Effects on Demineralized Dentin Surfaces for Improved Adhesive/Dentin Interface Bonding

    PubMed Central

    Dong, Xiaoqing; Chen, Meng; Wang, Yong; Yu, Qingsong

    2014-01-01

    Our previous work has shown that non-thermal plasma treatment of demineralized dentin significantly (p<0.05) improved adhesive/dentin bonding strength for dental composite restoration as compared with the untreated controls. This study is to achieve mechanistic understanding of the plasma treatment effects on dentin surface through investigating the plasma treated dentin surfaces and their interaction with adhesive monomer, 2-Hydroxyethyl methacrylate (HEMA). The plasma treated dentin surfaces from human third molars were evaluated by water contact angle measurements and scanning electron microscopy (SEM). It was found that plasma-treated dentin surface with subsequent HEMA immersion (Plasma/HEMA Treated) had much lower water contact angle compared with only plasma-treated (Plasma Treated) or only HEMA immersed (HEMA Treated) dentin surfaces. With prolong water droplet deposition time, water droplets spread out completely on the Plasma/HEMA Treated dentin surfaces. SEM images of Plasma/HEMA Treated dentin surfaces verified that dentin tubules were opened-up and filled with HEMA monomers. Extracted type I collagen fibrils, which was used as simulation of the exposed dentinal collagen fibrils after acid etching step, were plasma treated and analyzed with Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD) spectra. FT-IR spectra of the Plasma/HEMA Treated collage fibrils showed broadened amide I peak at 1660 cm−1 and amide II at 1550 cm−1, which indicate secondary structure changes of the collagen fibrils. CD spectra indicated that 67.4% collagen helix structures were denatured after plasma treatment. These experimental results demonstrate that non-thermal argon plasma treatment was very effective in loosing collagen structure and enhancing adhesive monomer penetration, which are beneficial to thicker hybrid layer and longer resin tag formation, and consequently enhance adhesive/dentin interface bonding. PMID:25267936

  14. A Mechanistic study of Plasma Treatment Effects on Demineralized Dentin Surfaces for Improved Adhesive/Dentin Interface Bonding.

    PubMed

    Dong, Xiaoqing; Chen, Meng; Wang, Yong; Yu, Qingsong

    2014-07-01

    Our previous work has shown that non-thermal plasma treatment of demineralized dentin significantly (p<0.05) improved adhesive/dentin bonding strength for dental composite restoration as compared with the untreated controls. This study is to achieve mechanistic understanding of the plasma treatment effects on dentin surface through investigating the plasma treated dentin surfaces and their interaction with adhesive monomer, 2-Hydroxyethyl methacrylate (HEMA). The plasma treated dentin surfaces from human third molars were evaluated by water contact angle measurements and scanning electron microscopy (SEM). It was found that plasma-treated dentin surface with subsequent HEMA immersion (Plasma/HEMA Treated) had much lower water contact angle compared with only plasma-treated (Plasma Treated) or only HEMA immersed (HEMA Treated) dentin surfaces. With prolong water droplet deposition time, water droplets spread out completely on the Plasma/HEMA Treated dentin surfaces. SEM images of Plasma/HEMA Treated dentin surfaces verified that dentin tubules were opened-up and filled with HEMA monomers. Extracted type I collagen fibrils, which was used as simulation of the exposed dentinal collagen fibrils after acid etching step, were plasma treated and analyzed with Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD) spectra. FT-IR spectra of the Plasma/HEMA Treated collage fibrils showed broadened amide I peak at 1660 cm(-1) and amide II at 1550 cm(-1), which indicate secondary structure changes of the collagen fibrils. CD spectra indicated that 67.4% collagen helix structures were denatured after plasma treatment. These experimental results demonstrate that non-thermal argon plasma treatment was very effective in loosing collagen structure and enhancing adhesive monomer penetration, which are beneficial to thicker hybrid layer and longer resin tag formation, and consequently enhance adhesive/dentin interface bonding.

  15. External Dentin Stimulation Induces ATP Release in Human Teeth.

    PubMed

    Liu, X; Wang, C; Fujita, T; Malmstrom, H S; Nedergaard, M; Ren, Y F; Dirksen, R T

    2015-09-01

    ATP is involved in neurosensory processing, including nociceptive transduction. Thus, ATP signaling may participate in dentin hypersensitivity and dental pain. In this study, we investigated whether pannexins, which can form mechanosensitive ATP-permeable channels, are present in human dental pulp. We also assessed the existence and functional activity of ecto-ATPase for extracellular ATP degradation. We further tested if ATP is released from dental pulp upon dentin mechanical or thermal stimulation that induces dentin hypersensitivity and dental pain and if pannexin or pannexin/gap junction channel blockers reduce stimulation-dependent ATP release. Using immunofluorescence staining, we demonstrated immunoreactivity of pannexin 1 and 2 in odontoblasts and their processes extending into the dentin tubules. Using enzymatic histochemistry staining, we also demonstrated functional ecto-ATPase activity within the odontoblast layer, subodontoblast layer, dental pulp nerve bundles, and blood vessels. Using an ATP bioluminescence assay, we found that mechanical or cold stimulation to the exposed dentin induced ATP release in an in vitro human tooth perfusion model. We further demonstrated that blocking pannexin/gap junction channels with probenecid or carbenoxolone significantly reduced external dentin stimulation-induced ATP release. Our results provide evidence for the existence of functional machinery required for ATP release and degradation in human dental pulp and that pannexin channels are involved in external dentin stimulation-induced ATP release. These findings support a plausible role for ATP signaling in dentin hypersensitivity and dental pain.

  16. Plasma treatment of dentin surfaces for improving self-etching adhesive/dentin interface bonding

    PubMed Central

    Dong, Xiaoqing; Li, Hao; Chen, Meng; Wang, Yong; Yu, Qingsong

    2015-01-01

    This study is to evaluate plasma treatment effects on dentin surfaces for improving self-etching adhesive and dentin interface bonding. Extracted unerupted human third molars were used after crown removal to expose dentin. One half of each dentin surface was treated with atmospheric non-thermal argon plasmas, while another half was untreated and used as the same tooth control. Self-etching adhesive and universal resin composite was applied to the dentin surfaces as directed. After restoration, the adhesive-dentin bonding strength was evaluated by micro-tensile bonding strength (μTBS) test. Bonding strength data was analyzed using histograms and Welch’s t-test based on unequal variances. μTBS test results showed that, with plasma treatment, the average μTBS value increased to 69.7±11.5 MPa as compared with the 57.1±17.5 MPa obtained from the untreated controls. After 2 months immersion of the restored teeth in 37 °C phosphate buffered saline (PBS), the adhesive-dentin bonding strengths of the plasma-treated specimens slightly decreased from 69.7±11.5 MPa to 63.9±14.4 MPa, while the strengths of the untreated specimens reduced from 57.1±17.5 MPa to 48.9±14.6 MPa. Water contact angle measurement and scanning electron microscopy (SEM) examination verified that plasma treatment followed by water rewetting could partially open dentin tubules, which could enhance adhesive penetration to form thicker hybrid layer and longer resin tags and consequently improve the adhesive/dentin interface quality. PMID:26273561

  17. How can sensitive dentine become hypersensitive and can it be reversed?

    PubMed Central

    Pashley, David H.

    2014-01-01

    This paper reviews a number of studies in oral biology and endodontics that deal with the reactivity of the pulpo-dentine complex in response to mechanical and immunological stimuli. It can be hypothesized that these reactions could also apply to changes in dentine sensitivity following periodontal procedures. Some of these changes involve neurogenic inflammation of the pulp under exposed open tubules; this increases the rate of outward fluid flow through the tubules, making the overlying exposed dentine more sensitive. Other changes may be due to inflammation-related nerve sprouting of pulpal nerves, which can lead to innervation ofmore tubules than normal. Changes may also involve upregulation of new, more sensitive ion channels in the membranes of these nerves. The goal of the paper is to increase awareness of the issues involved in dentine sensitivity, so that future investigators may develop agents or techniques to stimulate mechanisms that mitigate dentine sensitivity or to block mechanisms that aggravate the condition, for therapeutic effect. PMID:23929645

  18. The permeability of dentine from bovine incisors in vitro.

    PubMed

    Tagami, J; Tao, L; Pashley, D H; Horner, J A

    1989-01-01

    The permeability of coronal dentine was investigated by measuring the hydraulic conductance of dentine discs. Reductions in dentine thickness from the enamel side of disc resulted in a greater increase in permeability than reductions from the pulpal side. Scanning electron microscopy revealed fewer dentinal tubules with smaller diameters in superficial dentine than in deep dentine. The permeability of coronal incisor bovine dentine is six to eight times less than that of unerupted coronal human third molar dentine but similar to that of human root dentine.

  19. Tunicate-Inspired Gallic Acid/Metal Ion Complex for Instant and Efficient Treatment of Dentin Hypersensitivity.

    PubMed

    Prajatelistia, Ekavianty; Ju, Sung-Won; Sanandiya, Naresh D; Jun, Sang Ho; Ahn, Jin-Soo; Hwang, Dong Soo

    2016-04-20

    Dentin hypersensitivity is sharp and unpleasant pains caused by exposed dentinal tubules when enamel outside of the tooth wears away. The occlusion of dentinal tubules via in situ remineralization of hydroxyapatite is the best method to alleviate the symptoms caused by dentin hypersensitivity. Commercially available dental desensitizers are generally effective only on a specific area and are relatively toxic, and their performance usually depends on the skill of the clinician. Here, a facile and efficient dentin hypersensitivity treatment with remarkable aesthetic improvement inspired by the tunicate-self-healing process is reported. As pyrogallol groups in tunicate proteins conjugate with metal ions to heal the torn body armor of a tunicate, the ingenious mechanism by introducing gallic acid (GA) as a cheap, abundant, and edible alternative to the pyrogallol groups of the tunicate combined with a varied daily intake of metal ion sources is mimicked. In particular, the GA/Fe(3+) complex exhibits the most promising results, to the instant ≈52% blockage in tubules within 4 min and ≈87% after 7 d of immersion in artificial saliva. Overall, the GA/metal ion complex-mediated coating is facile, instant, and effective, and is suggested as an aesthetic solution for treating dentin hypersensitivity.

  20. Leeuwenhoek and the structure of dentine.

    PubMed

    O'Sullivan, R; Flannelly, M

    1990-01-01

    This short paper includes extracts from the original translations of Leeuwenhoek's descriptions of the histology of teeth, investigates his findings and demonstrates that in addition to describing dentinal tubules, he may have identified the presence of calcospherites within that tissue.

  1. Heat shock protein 27 expression in human proximal tubule cells exposed to lethal and sublethal concentrations of CdCl2.

    PubMed Central

    Somji, S; Sens, D A; Garrett, S H; Sens, M A; Todd, J H

    1999-01-01

    The expression of hsp 27 mRNA and protein was determined in cultured human proximal tubule (HPT) cells exposed to lethal and sublethal concentrations of Cd2+ under both acute and extended conditions. Initial procedures demonstrated that HPT cells display the classic stress response following physical and chemical stress. Heat stress (42.5 degrees C for 1 hr) caused an increase in both hsp 27 mRNA and protein as well as a shift in the protein to a more phosphorylated state. Results were similar when the cells were subjected to chemical stress (exposure to 100 microM sodium arsenite for 4 hr). Acute exposure to 53 microM CdCl2 for 4 hr also resulted in an increase in hsp 27 mRNA and protein and a shift to the more phosphorylated protein isoform. Extended Cd2+ exposure involved continuous treatment with Cd2+ at both lethal and sublethal levels over a 16-day time course. The results of this treatment showed that chronic exposure to Cd2+ failed to increase either hsp 27 mRNA or protein expression in HPT cells, even at lethal Cd2+ concentrations. In fact, hsp 27 protein levels decreased as compared to controls at both lethal and sub-lethal exposure to Cd2+. These findings imply that hsp 27 expression in human proximal tubule cells may have two distinct modes depending on the nature (acute vs. chronic) of the stress. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 PMID:10379001

  2. Structural modifications induced in dentin by femtosecond laser

    NASA Astrophysics Data System (ADS)

    Le, Quang-Tri; Bertrand, Caroline; Vilar, Rui

    2016-12-01

    The structural and chemical modifications induced in dentin by ultrafast laser ablation were studied. The laser experiments were performed with a Yb:KYW chirped-pulse-regenerative amplification laser system (560-fs pulse duration, 1030-nm radiation wavelength), fluences in the range 2 to 14 J/cm2, 1-kHz pulse repetition rate, and 5-mm/s scanning speed. The ablation surfaces were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The ablation surfaces produced with 2 J/cm2 presented an irregular morphology with exposed dentinal tubules and no evidence of thermal effects. For 7 and 14 J/cm2, the ablation surfaces were covered by a layer of redeposited ablation debris, consisting mainly of amorphous calcium phosphate. This layer is weakly adherent to the underlying tissue and can be easily removed by ultrasonication, revealing a surface with a morphology similar to the one obtained with 2 J/cm2. The constitution of the dentin ablation surfaces is similar to the constitution of pristine dentin, showing that, within this fluence range, the laser treatment does not significantly modify the structure and constitution of dentin. The results achieved suggest an ablation mechanism where collagen is preferentially decomposed by the laser radiation, reducing the tissue cohesive strength and leading, ultimately, to its ablation.

  3. Dentine hypersensitivity: a review of its aetiology, pathogenesis and management.

    PubMed

    Sykes, L M

    2007-03-01

    Dentine hypersensitivity (DH) is defined as pain arising from exposed dentine and represents a distinct clinical entity. Reported cases are increasing particularly among the younger age groups and are thought to be due to acidogenic diets, destructive habits, poor tooth brushing techniques, and the increased use of tooth whitening products. Dentine exposure may be due to a number of processes, both physical and chemical, that lead to either loss of enamel/ cementum or loss of gingival tissue. These causative factors seldom act in isolation and include erosion, abrasion, attrition, abfraction, bruxing, bleaching, medication, ageing, genetic conditions, gingival recession, and periodontal disease or procedures. There are diverse range of treatment products available, which aim at either occluding the dentinal tubules or blocking the neural transmission from the pulp. Most reversible options make use of chemical agents such as fluorides, oxalate, strontium or potassium salts, or dentine-bonding agents. Non-reversible options should only be employed after one or more of the reversible options have been attempted. These usually involve placement of permanent restorations, occlusal adjustments or periodontal flap surgery. Careful diagnosis, patient counseling and management strategies are crucial to the success of any intervention.

  4. Expression of the constitutive and inducible forms of heat shock protein 70 in human proximal tubule cells exposed to heat, sodium arsenite, and CdCl(2).

    PubMed Central

    Somji, S; Todd, J H; Sens, M A; Garrett, S H; Sens, D A

    1999-01-01

    We determined the expression of the constitutive (hsc 70) and inducible (hsp 70) forms of heat shock protein 70 mRNA and protein in human proximal tubule (HPT) cells exposed to lethal and sublethal concentrations of Cd(+2) under both acute and extended conditions of exposure. The HPT cells exhibited the classic heat shock response when subjected to a physical (heat) or chemical stress (sodium arsenite); hsc 70 mRNA and protein levels were constant or slightly increased, whereas hsp 70 mRNA and protein were greatly elevated. Acute exposure to 53.4 microM CdCl(2) for 4 hr failed to increase either hsc 70 mRNA or protein, a finding similar to that observed under classic conditions of stress. However, under identical conditions of acute exposure to Cd(2+), the expected increase in hsp 70 protein level was suppressed as compared to that found under classic conditions of physical or chemical stress. The decrease in hsp 70 protein level correlated to the reduced expression of mRNA from the hsp 70B gene. The expression of mRNA from the hsp 70A and hsp 70C genes was similar to that found when the cells were treated with heat shock or sodium arsenite. We modeled an extended exposure to Cd(2+) by treating the cells continuously with Cd(2+) at both lethal and sublethal levels over a 16-day time course. Chronic exposure to Cd(2+) failed to increase either hsc 70 mRNA or protein levels in the HPT cells at a nonlethal dosage level and decreased hsc 70 mRNA and protein levels late in the time course of lethal exposure. Under identical conditions, the expression of hsp 70 protein remained at basal levels that were only marginally detectable throughout the time course. Hsp 70A and hsp 70C mRNA levels were unaltered by extended exposure to Cd(2+), and hsp 70B mRNA was not detected during the 16-day time course. Cd(2+) is a poor inducer of hsc 70 and hsp 70 in the proximal tubule under both acute and long-term exposure. These results reinforce the fact that the expression of hsp 70

  5. Dentin hypersensitivity: Recent trends in management

    PubMed Central

    Miglani, Sanjay; Aggarwal, Vivek; Ahuja, Bhoomika

    2010-01-01

    Dentinal hypersensitivity (DH) is a common clinical condition usually associated with exposed dentinal surfaces. It can affect patients of any age group and most commonly affects the canines and premolars of both the arches. This article concisely reviews the patho-physiology, mechanism and clinical management of the DH. Treatment of DH should start with an accurate diagnosis. Differential diagnosis should be made and all other probable causes should be excluded. An often neglected phase of clinical management of DH is the identification and treatment of the causative factors of DH. By removing the etiological factors, the condition can be even prevented from occurring or recurring. There are various treatment modalities available which can be used at home or may be professionally applied. The “at home” desensitizing agents include toothpastes, mouthwashes or chewing gums and they act by either occluding the dentinal tubules or blocking the neural transmission. This article also discusses the recent treatment options like bioglass, Portland cement, lasers and casein phosphopeptide. PMID:21217949

  6. Effects of distance from the pulp and thickness on the hydraulic conductance of human radicular dentin.

    PubMed

    Fogel, H M; Marshall, F J; Pashley, D H

    1988-11-01

    The purposes of this study were: (1) to measure the effect of distance from the pulp on the hydraulic conductance of human radicular dentin; (2) to determine the influence of dentin thickness on the rates of fluid flow; and (3) to attempt to correlate dentinal tubule densities and diameters with root dentin hydraulic conductance. Dentin slabs prepared from extracted, unerupted, human third molar teeth were placed in a split-chamber device to permit quantitation of fluid filtration rate (hydraulic conductance). In the SEM portion of the study, dentinal tubule numbers and diameters were recorded. The results indicated that radicular dentin hydraulic conductance decreased with distance from the pulp and with increasing dentin thickness. Tubule density and diameter correlated well with the measured hydraulic conductances. The relatively low hydraulic conductance of outer root dentin makes it a significant barrier to fluid movement across root structure.

  7. Morphology of the dentin structure of sloths Bradypus tridactylus: a light and scanning electron microscopy investigation.

    PubMed

    Santana, L N S; Barbosa, L V M; Teixeira, F B; Costa, A M P; Fernandes, L M P; Lima, R R

    2013-12-01

    The aim of this study was to describe the dentine morphology of sloths (Bradypus tridactylus). The sloth teeth were removed and prepared for light microscopy (LM) and scanning electron microscopy analyses (SEM). LM revealed two patterns of tubular dentins: an outer with dentinary tubules over the all tooth length and one in the inner part with larger diameter and more spaced tubules, when compared to those present in the outer dentine. These findings were confirmed by SEM, which revealed a tubular pattern in the outer dentine like in humans. The inner dentine displayed pared grouped tubules that were characterized as vascular channels. It can be concluded that this sloth species present two types of dentins: an inner dentin (ortodentin) and an outer dentin characterized as a vascular dentin. This suggests a partial evolutive/adaptive process of this dental tissue, as compared to other mammalian species.

  8. Lack of formic acid production in rat hepatocytes and human renal proximal tubule cells exposed to chloral hydrate or trichloroacetic acid.

    PubMed

    Lock, Edward A; Reed, Celia J; McMillan, Joellyn M; Oatis, John E; Schnellmann, Rick G

    2007-02-12

    The industrial solvent trichloroethylene (TCE) and its major metabolites have been shown to cause formic aciduria in male rats. We have examined whether chloral hydrate (CH) and trichloroacetic acid (TCA), known metabolites of TCE, produce an increase in formic acid in vitro in cultures of rat hepatocytes or human renal proximal tubule cells (HRPTC). The metabolism and cytotoxicity of CH was also examined to establish that the cells were metabolically active and not compromised by toxicity. Rat hepatocytes and HRPTC were cultured in serum-free medium and then treated with 0.3-3mM CH for 3 days or 0.03-3mM CH for 10 days, respectively and formic acid production, metabolism to trichloroethanol (TCE-OH) and TCA and cytotoxicity determined. No increase in formic acid production in rat hepatocytes or HRPTC exposed to CH was observed over and above that due to chemical degradation, neither was formic acid production observed in rat hepatocytes exposed to TCA. HRPTC metabolized CH to TCE-OH and TCA with a 12-fold greater capacity to form TCE-OH versus TCA. Rat hepatocytes exhibited a 1.6-fold and three-fold greater capacity than HRPTC to form TCE-OH and TCA, respectively. CH and TCA were not cytotoxic to rat hepatocytes at concentrations up to 3mM/day for 3 days. With HRPTC, one sample showed no cytotoxicity to CH at concentrations up to 3mM/day for 10 days, while in another cytotoxicity was seen at 1mM/day for 3 days. In summary, increased formic acid production was not observed in rat hepatocytes or HRPTC exposed to TCE metabolites, suggesting that the in vivo response cannot be modelled in vitro. CH was toxic to HRPTC at millimolar concentrations/day over 10 days, while glutathione derived metabolites of TCE were toxic at micromolar concentrations/day over 10 days [Lock, E.A., Reed, C.J., 2006. Trichloroethylene: mechanisms of renal toxicity and renal cancer and relevance to risk assessment. Toxicol. Sci. 19, 313-331] supporting the view that glutathione derived

  9. The induction of dentin bridge-like structures by constructs of subcultured dental pulp-derived cells and porous HA/TCP in porcine teeth.

    PubMed

    Ando, Yusuke; Honda, Masaki J; Ohshima, Hayato; Tonomura, Akiko; Ohara, Takayuki; Itaya, Toshimitsu; Kagami, Hideaki; Ueda, Minoru

    2009-02-01

    The purpose of this study was to investigate dentin-bridge formation in teeth following the transplantation of dental pulp-derived cells seeded on hydroxyapatite/tricalcium phosphate (HA/TCP) scaffolds. The dental pulp tissues were removed from the extracted first molar teeth of miniature pigs and single cell populations were subcultured. Second-passage cells that had alkaline phosphatase activity were combined with scaffolds. Cell-scaffold constructs were placed in contact with the exposed pulp tissue. The dimensions of the exposed pulp site were approximately 1-2.5 mm in diameter and 2-3 mm in depth from the tooth surface. After placing the constructs, the tooth was restored with composite resin. Six weeks after transplantation, hard tissue formation was observed on the pulp tissue in histology. Dentinal tubule-like structures were observed in most of the hard tissue generated, and columnar cells, which showed positive immunoreactions with dentin sialoprotein (DSP) and heat shock protein (HSP)-25, were aligned beneath the hard tissues. When only scaffolds were placed on the pulp tissues, particles of hard tissue were formed, however dentinal tubule-like structures and odontoblasts were not observed despite the formation of hard tissue. In conclusion, the implantation of dental pulp constructs into pulp exposed stimulates the formation of calcified dentin-like structures.

  10. Exposed Dentin: Influence of Cleaning Procedures and Simulated Pulpal Pressure on Bond Strength of a Universal Adhesive System

    PubMed Central

    2017-01-01

    Purpose To compare various pre-treatments serving as cleaning procedures of dentin on the bond strength of resin composite promoted by a universal adhesive system applied either in the absence or presence of simulated pulpal pressure. Materials and Methods Prior to application of the adhesive system (Scotchbond Universal) and resin composite (Filtek Z250), ground dentin surfaces were given one of five pre-treatments either without or with simulated pulpal pressure: 1) no pre-treatment, adhesive system in “self-etch” mode, 2) phosphoric acid etching, adhesive system in “total-etch” mode, 3) polishing with pumice on prophylaxis cup, 4) air abrasion with AIR-FLOW PLUS powder, 5) air abrasion with AIR-FLOW PERIO powder; n = 20/group of pre-treatment. After storage (37°C, 100% humidity, 24 h), micro shear bond strength was measured and data analyzed with parametric ANOVA including Bonferroni-Holm correction for multiple testing followed by Student’s t tests (significance level: α = 0.05). Results The ANOVA found type of pre-treatment and simulated pulpal pressure to have no significant effect on dentin bond strength. The explorative post-hoc tests showed a negative effect of simulated pulpal pressure for phosphoric acid etching (adhesive system in “total-etch” mode; p = 0.020), but not for the other four pre-treatments (all p = 1.000). Conclusion Air abrasion with powders containing either erythritol and chlorhexidine (AIR-FLOW PLUS) or glycine (AIR-FLOW PERIO) yielded dentin bond strengths similar to no pre-treatment, phosphoric acid etching, or polishing with pumice. Simulated pulpal pressure reduced the bond strength only when the self-etch adhesive system was used in total-etch mode. PMID:28081572

  11. Effect of various laser irradiations on the mineral content of dentin

    PubMed Central

    Dilber, Erhan; Malkoc, Meral Arslan; Ozturk, A. Nilgun; Ozturk, Firat

    2013-01-01

    Objective: The aim of this study was to evaluate the mineral content of dentin irradiation with Erbium: yttrium-aliminum-garnet (Er:YAG), Neodmiyum:yttrium-aliminum garnet (Nd:YAG) and potassium titanium phosphate (KTP) laser used for in the treatment of dentin hypersensitivity. Methods: Six extracted wisdom, unerupted molar teeth were used in this study. The enamel of the teeth was removed with a conventional bur under water cooling to expose the dentin surface. The teeth were mounted in a slow-speed, diamond-saw, sectioning machine. Two dentin slabs were obtained from each tooth and each slab was sectioned so that 4 slabs were made from each teeth. Then dentin slabs were randomly divided into four groups. Group A: Control Group, Group B: Er:YAG laser, Group C: Nd:YAG laser, Group D: KTP laser. The levels of Ca, K, Mg, Na,P and Ca/P mineral ratio in each dentin slab were measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Data were analysed by one way analysis of variance (ANOVA) and Tukey HSD tests. One sample from each group was prepared for scanning electron microscopy (SEM). Results: There were no significant differences between the groups for Ca, K, Mg, Na,P and Ca/P mineral ratio (P>.05). SEM photographs indicated that there were melted areas around the exposed dentin tubules in groups treated with Er:YAG and KTP lasers. Conclusion: This study demonstrated that laser etching with the Er:YAG, Nd:YAG, KTP laser systems did not affect the compositional structure of the dentin surfaces. PMID:23407579

  12. Effects of industrial noise on circumpulpar dentin - a field emission scanning electron microscopy and energy dispersive spectroscopy analysis

    PubMed Central

    Cavacas, Maria Alzira; Tavares, Vitor; Oliveira, Maria João; Oliveira, Pedro; Sezinando, Ana; Martins dos Santos, José

    2013-01-01

    Chronic exposure to Industrial Noise (IN), rich in Low Frequency Noise (LFN), causes systemic fibrotic transformation and sustained stress. Dental wear, significantly increased with exposure to LFN, affects the teeth particularly through the circumpulpar dentin. Our goal is to understand the consequences of IN exposure on the circumpulpar dentin of Wistar rats. 10 Wistar rats were exposed to IN for 4 months, according to an occupationally simulated time schedule and 10 animals were used as age-matched controls. The first and the second upper and lower molars of each animal were processed for observation by Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive Spectroscopy (EDS) analysis was performed. In exposed animals FESEM showed a 2.0 to 6.0 μm-dense mineral band between dentin and the pulp with no regular continuity with the tubules. This structure had a few tubules where the odontoblasts processes could be observed embedded within the band and collagen fibers were trapped inside. EDS analysis revealed that it was hydroxyapatite similar to dentin, with a higher carbon content. FESEM results show that the band may be tertiary reparative dentin formed by odontoblast-like cells, but the increased amount of carbon (EDS) could mean that it is sclerotic dentin. IN should be acknowledge as a strong stimulus, able to cause an injury to odontoblasts and to the formation of reparative tertiary dentin, in a process that may accelerate the aging of the teeth, either by direct impact of acoustic pressure pulsations or by increased stress and dental wear. PMID:24294356

  13. Effects of air-drying in vitro on human dentine permeability.

    PubMed

    Pashley, D H; Stewart, F P; Galloway, S E

    1984-01-01

    The effects of evaporation produced by air blasts of 0, 0.5, 2 or 5 min to dentine in vitro were evaluated by measuring dentine hydraulic conductance before and after each trial. When the tubules were filled with water, even prolonged evaporation had no effect on dentine permeability. Tubules filled with physiological salt solution produced a time-dependent decrease in dentine permeability. Tubules filled with 1.5 per cent albumin in water gave the largest reductions in dentine permeability. These effects were more marked in unetched as opposed to acid-etched dentine. The results suggest that part of the reduction in dentine sensitivity produced clinically by prolonged air blasts may be due to precipitation of organic and inorganic constituents of dentinal fluid at the surface.

  14. Inelastic deformation and microcracking process in human dentin.

    PubMed

    Eltit, Felipe; Ebacher, Vincent; Wang, Rizhi

    2013-08-01

    Dentin is a mineralized collagen tissue with robust mechanical performance. Understanding the mechanical behavior of dentin and its relations to the dentinal structure can provides insight into the design strategies to achieve tooth functions. This study focuses on the inelastic deformation of human dentin and its underlying mechanisms. By combining four-point bending tests with fluorescent staining and laser scanning confocal microscopy, it was found that human dentin, especially root dentin, exhibited significant inelastic deformation and developed extensive microdamage in the form of microcracks prior to fracture. Dense and wavy microcracks spread uniformly across the tensile surface of root dentin, while compressive microcracks formed cross-hatched patterns. The presence of peritubular dentin in coronal dentin dramatically decreased the extent of microcracking, reducing inelasticity. Dentinal tubules were found to be initiation sites of both tensile and compressive microcracks. A unique crack propagation process was observed in root dentin under tension: numerous ring-shaped cracks formed at each dentinal tubule ahead of a growing crack tip. The advance of the tensile microcracks occurred by the merging of those ring-shaped cracks. The current findings on the microcracking process associated with inelastic deformation helps to understand the nature of strength and toughness in dentin, as well as the mechanical significance for structural variations across the whole tooth.

  15. Comparison of the Effect of Dentin Bonding, Dentin Sealing Agents on the Microleakage of Provisional Crowns Fabricated with Direct and Indirect Technique-An Invitro Study

    PubMed Central

    Muthukumar, B; Kumar, M Vasantha

    2015-01-01

    Background Postoperative sensitivity after temporization is a common complaint in Fixed Partial Denture patients. It is caused by weak and ill fitting temporary restorations which results in microleakage. This can be controlled by providing good temporary restorations and by coating the exposed dentinal tubules of the prepared tooth with dentin bonding agent or dental varnish. Aim The purpose of the study was to determine the effect of dentin-bonding, dentin sealing agents on the microleakage of temporary crowns made by tooth colored auto polymerizing resin fabricated with direct and indirect technique. Materials and Methods Thirty premolar and molar human teeth were collected which were extracted recently was used for the study. The teeth were marked and divided into 3 groups each containing 10 nos. They were individually mounted with self-cure acrylic resin. It was then mounted on a milling machine and crown preparations done. Temporary crowns were fabricated by direct and indirect method with two types of materials. In group A (Control group), the temporary crowns fabricated with both direct and indirect method were cemented directly with temporary luting cement. In group B dentine-bonding agent (solobond M) was applied once to the prepared surface of each tooth specimen before the cementation of temporary crowns where as in case of group C a single layer of dental varnish is applied prior to crown cementation. The entire specimens were immersed in 1% methylene blue and allowed to undergo thermal treatment. It was then sectioned in a hard tissue microtome. Each section was evaluated for dye penetration into the dentin tubules by comparing it with a visual scale. Statistical Analysis SPSS Version 13 software was used for non-parametric data analysis by a qualified statistician. P-values less than 0.05 (p-value<0.05) were considered to be statistically significant. Results Group B (Dentin Bonding Agent) specimens cemented with crowns fabricated in direct technique

  16. Cytotoxicity of DP-bioglass paste used for treatment of dentin hypersensitivity.

    PubMed

    Kuo, Tien-Chun; Lee, Bor-Shiunn; Kang, Shu-Han; Lin, Feng-Huei; Lin, Chun-Pin

    2007-04-01

    DP-bioglass mixed with 30% phosphoric acid has been suggested to treat dentin hypersensitivity because the material is able to produce homogeneous occlusion of exposed dentinal tubules and is able to provide a sealing depth of up to 60 microm. The purpose of this study was to investigate the relative cytotoxic effect of the DP-bioglass paste, intermediate restorative material (IRM; DeTrey, Dentsply, Germany), and commercial desensitizing agent (Abmindent; Abmin Technologies Ltd, Turku, Finland) on human dental pulp cells by using a transwell insert model and a dentin-disc model. Cell viability was measured by means of a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results of this study indicated that cell viability for the DP-bioglass paste did not differ significantly from those of the IRM or Abmindent in the transwell insert model. In addition, MTT results of DP-bioglass paste were similar to the control group in the dentin-disc model. The results indicated that DP-bioglass paste was a highly biocompatible material and could potentially serve as an effective material for treatment of dentin hypersensitivity.

  17. Micro energy-dispersive x-ray fluorescence spectrometry study of dentin coating with nanobiomaterials

    NASA Astrophysics Data System (ADS)

    Soares, Luís. Eduardo Silva; Nahorny, Sídnei; Marciano, Fernanda Roberta; Zanin, Hudson; Lobo, Anderson de Oliveira

    2015-06-01

    New biomaterials such as multi-walled carbon nanotubes oxide/graphene oxide (MWCNTO/GO), nanohydroxyapatite (nHAp) and combination of them together or not to acidulated phosphate fluoride gel (F) have been tested as protective coating before root dentin erosion. Fourteen bovine teeth were cleaned, polished, divided into two parts (n=28) and assigned to seven groups: (Control) - without previous surface treatment; F treatment; nHAp; MWCNTO/GO; F+nHAp; F+MWCNTO/GO and F+MWCNTO/GO/nHAp composites. Each sample had two sites of pre-treatments: acid etched area and an area without treatment. After the biomaterials application, the samples were submitted to six cycles (demineralization: orange juice, 10 min; remineralization: artificial saliva, 1 h). Micro energy-dispersive X-ray fluorescence spectrometry (μ-EDXRF) mapping area analyses were performed after erosive cycling on both sites (n=84). μ-EDXRF mappings showed that artificial saliva and MWCNTO/GO/nHAp/F composite treatments produced lower dentin demineralization than in the other groups. Exposed dentin tubules allowed better interaction of nanobiomaterials than in smear layer covered dentin. Association of fluoride with other biomaterials had a positive influence on acid etched dentin. MWCNTO/GO/nHAp/F composite treatment resulted in levels of demineralization similar to the control group.

  18. Biological effects of a root conditioning agent for dentin surface modification in vitro

    PubMed Central

    Lee, Jue-Yeon; Seol, Yang-Jo; Park, Jang-Ryul; Park, Yoon-Jeong

    2010-01-01

    Purpose Connective tissue reattachment to periodontally damaged root surfaces is one of the most important goals of periodontal therapy. The aim of this study was to develop a root conditioning agent that can demineralize and detoxify the infected root surface. Methods Dentin slices obtained from human teeth were treated with a novel root planing agent for 2 minutes and then washed with phosphate-buffered saline. Smear layer removal and type I collagen exposure were observed by scanning electron microscopy (SEM) and type I collagen immunostaining, respectively. Cell attachment and lipopolysaccharides (LPS) removal demonstrated the efficiency of the root conditioning agent. Results SEM revealed that the smear layer was entirely removed and the dentinal tubules were opened by the experimental gel. Type I collagen was exposed on the surfaces of the dentin slices treated by the experimental gel, which were compared with dentin treated with other root planing agents. Dentin slices treated with the experimental gel showed the highest number of attached fibroblasts and flattened cell morphology. The agar diffusion assay demonstrated that the experimental gel also has effective antimicrobial activity. Escherichia coli LPS were effectively removed from well plates by the experimental gel. Conclusions These results demonstrated that this experimental gel is a useful tool for root conditioning of infected root surfaces and can also be applied for detoxification of ailing implant surface threads. PMID:21246015

  19. Effects of chloramines and sodium hypochlorite on carious dentin.

    PubMed

    Tonami, Ken-ichi; Araki, Kouji; Mataki, Shiro; Kurosaki, Norimasa

    2003-06-01

    In chemo-mechanical caries removal procedures, chloramines are typically used for chemical softening of carious dentin. However, the specific effect of chloramines to be compared to sodium hypochlorite has not been sufficiently clarified. In present study, the effect of chloramines used in the Carisolv-system on carious dentin mechanical properties and morphology were investigated, using Vickers hardness test and scanning electron microscopy (SEM). Sections of permanent teeth with dentin caries were treated with chloramines, prepared by mixing amino acids (glutamic acid, lysine, and leucine) with sodium hypochlorite or with sodium hypochlorite alone or with purified water. There was a tendency that the application of the sodium hypochlorite solution softened the sound dentin and/or inner layer of carious dentin more than the application of the chloramines solution did. In SEM observations, the application of chloramines resulted in opening dentinal tubules in the outer layer of carious dentin: Occluded dentinal tubules were seen after sodium hypochlorite application. There is a possibility that the amino acids in the Carisolv-system decrease the aggressive effect of sodium hypochlorite on sound dentin and/or inner layer of carious dentin and also would enhance the disrupting effect on degenerated collagen in carious dentin outer layer.

  20. Bovine and equine peritubular and intertubular dentin.

    PubMed

    Stock, S R; Deymier-Black, A C; Veis, A; Telser, A; Lux, E; Cai, Z

    2014-09-01

    Dentin contains 1-2μm diameter tubules extending from the pulp cavity to near the junction with enamel. Peritubular dentin (PTD) borders the tubule lumens and is surrounded by intertubular dentin (ITD). Differences in PTD and ITD composition and microstructure remain poorly understood. Here, a (∼200nm)(2), 10.1keV synchrotron X-ray beam maps X-ray fluorescence and X-ray diffraction simultaneously around tubules in 15-30μm thick bovine and equine specimens. Increased Ca fluorescence surrounding tubule lumens confirms that PTD is present, and the relative intensities in PTD and ITD correspond to carbonated apatite (cAp) volume fraction of ∼0.8 in PTD vs. 0.65 assumed for ITD. In the PTD near the lumen edges, Zn intensity is strongly peaked, corresponding to a Zn content of ∼0.9mgg(-1) for an assumed concentration of ∼0.4mgg(-1) for ITD. In the equine specimen, the Zn K-edge position indicates that Zn(2+) is present, similar to bovine dentin (Deymier-Black et al., 2013), and the above edge structure is consistent with spectra from macromolecules related to biomineralization. Transmission X-ray diffraction shows only cAp, and the 00.2 diffraction peak (Miller-Bravais indices) width is constant from ITD to the lumen edge. The cAp 00.2 average preferred orientation is axisymmetric (about the tubule axis) in both bovine and equine dentin, and the axisymmetric preferred orientation continues from ITD through the PTD to the tubule lumen. These data indicate that cAp structure does not vary from PTD to ITD.

  1. In vitro photodynamic antimicrobial chemotherapy in dentine contaminated by cariogenic bacteria

    NASA Astrophysics Data System (ADS)

    Melo, M. A. S.; de-Paula, D. M.; Lima, J. P. M.; Borges, F. M. C.; Steiner-Oliveira, C.; Nobre-Dos-Santos, M.; Zanin, I. C. J.; Barros, E. B.; Rodrigues, L. K. A.

    2010-06-01

    The development of a method to ensure bacterial-free substrates without extensive cavity preparation would be highly useful to dentistry, since there is no currently available effective method for killing residual bacteria in dentinal tissue. This randomized in vitro study determined parameters for using toluidine blue O (TBO) with a light-emitting diode (LED) for dentine caries disinfection and monitored intrapulpal/periodontal temperatures during irradiation. Occlusal human dentine slabs were immersed in Streptococcus mutans culture for demineralization induction. Slabs were allocated to 10 groups ( n = 15), which were treated with 0.1 mg ml-1 TBO with 5 min of incubation time or 0.9% NaCl solution for 5, 10 or 15 min, and submitted or not to irradiation for 5, 10 or 15 min (47, 94, and 144 J/cm2). Before and after treatments, dentine samples were analyzed with regard to S. mutans counts. In whole teeth, temperature in pulp and periodontium was measured by thermocouples during irradiation. Kruskal-Wallis/Student-Newman-Keuls, and ANOVA/Tukey test were respectively utilized to compare log reductions and temperature rises between groups. Bacterial reduction was observed when dentine was exposed to both TBO and LED at all irradiation times, as well as to LED alone for 10 and 15 min. Temperature increases lower than 2°C were observed for either pulp or periodontium. Concluding, LED combined with TBO is a safe and effective approach for dentine caries disinfection. Nevertheless, additional studies should be conducted to determine the influence of the irradiation in S. mutans viability in dentinal surface/tubules.

  2. Transmission of Curing Light through Moist, Air-Dried, and EDTA Treated Dentine and Enamel

    PubMed Central

    Uusitalo, E.; Varrela, J.; Lassila, L.; Vallittu, P. K.

    2016-01-01

    Objective. This study measured light transmission through enamel and dentin and the effect of exposed dentinal tubules to light propagation. Methods. Light attenuation through enamel and dentin layers of various thicknesses (1 mm, 2 mm, 3 mm, and 4 mm) was measured using specimens that were (1) moist and (2) air-dried (n = 5). Measurements were repeated after the specimens were treated with EDTA. Specimens were transilluminated with a light curing unit (maximum power output 1869 mW/cm2), and the mean irradiance power of transmitting light was measured. The transmission of light through teeth was studied using 10 extracted intact human incisors and premolars. Results. Transmitted light irradiance through 1 mm thick moist discs was 500 mW/cm2 for enamel and 398 mW/cm2 for dentin (p < 0.05). The increase of the specimen thickness decreased light transmission in all groups (p < 0.005), and moist specimens attenuated light less than air-dried specimens in all thicknesses (p < 0.05). EDTA treatment increased light transmission from 398 mW/cm2 to 439 mW/cm2 (1 mm dentin specimen thickness) (p < 0.05). Light transmission through intact premolar was 6.2 mW/cm2 (average thickness 8.2 mm) and through incisor was 37.6 mW/cm2 (average thickness 5.6 mm). Conclusion. Light transmission through enamel is greater than that through dentin, probably reflecting differences in refractive indices and extinction coefficients. Light transmission through enamel, dentin, and extracted teeth seemed to follow Beer-Lambert's law. PMID:27446954

  3. Changes in gene expression in human renal proximal tubule cells exposed to low concentrations of S-(1,2-dichlorovinyl)-L-cysteine, a metabolite of trichloroethylene

    SciTech Connect

    Lock, Edward A. . E-mail: e.lock@ljmu.ac.uk; Barth, Jeremy L.; Argraves, Scott W.; Schnellmann, Rick G.

    2006-10-15

    Epidemiology studies suggest that there may be a weak association between high level exposure to trichloroethylene (TCE) and renal tubule cell carcinoma. Laboratory animal studies have shown an increased incidence of renal tubule carcinoma in male rats but not mice. TCE can undergo metabolism via glutathione (GSH) conjugation to form metabolites that are known to be nephrotoxic. The GSH conjugate, S-(1,2-dichlorovinyl)glutathione (DCVG), is processed further to the cysteine conjugate, S-(1,2-dichlorovinyl)-L-cysteine (DCVC), which is the penultimate nephrotoxic species. We have cultured human renal tubule cells (HRPTC) in serum-free medium under a variety of different culture conditions and observed growth, respiratory control and glucose transport over a 20 day period in medium containing low glucose. Cell death was time- and concentration-dependent, with the EC{sub 5} for DCVG being about 3 {mu}M and for DCVC about 7.5 {mu}M over 10 days. Exposure of HRPTC to sub-cytotoxic doses of DCVC (0.1 {mu}M and 1 {mu}M for 10 days) led to a small number of changes in gene expression, as determined by transcript profiling with Affymetrix human genome chips. Using the criterion of a mean 2-fold change over control for the four samples examined, 3 genes at 0.1 {mu}M DCVC increased, namely, adenosine kinase, zinc finger protein X-linked and an enzyme with lyase activity. At 1 {mu}M DCVC, two genes showed a >2-fold decrease, N-acetyltransferase 8 and complement factor H. At a lower stringency (1.5-fold change), a total of 63 probe sets were altered at 0.1 {mu}M DCVC and 45 at 1 {mu}M DCVC. Genes associated with stress, apoptosis, cell proliferation and repair and DCVC metabolism were altered, as were a small number of genes that did not appear to be associated with the known mode of action of DCVC. Some of these genes may serve as molecular markers of TCE exposure and effects in the human kidney.

  4. Effects of CO2 laser energy on dentin permeability.

    PubMed

    Pashley, E L; Horner, J A; Liu, M; Kim, S; Pashley, D H

    1992-06-01

    The effect of a CO2 laser on the structure and permeability of smear layer-covered human dentin was evaluated in vitro. Three different energy levels were used (11, 113, and 566 J/cm2). The lowest exposure to the laser energy increased dentin permeability, measured as a hydraulic conductance, due to partial measured as a hydraulic conductance, due to partial loss of the superficial smear layer and smear plugs. The intermediate energy level also increased dentin permeability by crater formation, making the dentin thinner. The lack of uniform glazing of the surface of the crater, leaving its surface porous and in communication with the underlying dentinal tubules also contributed to the increase in dentin permeability seen with the intermediate laser energy. The highest laser energy produced complete glazing of the crater surfaces and sealed the dentinal tubules beneath the crater. However, it also completely removed the smear layer in a halo zone about 100-microns wide around each crater which increased the permeability of the pericrater dentin at the same time it decreased the permeability of the dentin within the crater. The combined use of scanning electron microscopy and permeability measurements provides important complementary information that is essential in evaluating the effects of lasers on dentin.

  5. Evaluation of plasma treatment effects on improving adhesive/dentin bonding by using the same tooth controls and varying cross-sectional surface areas

    PubMed Central

    Dong, Xiaoqing; Ritts, Andy Charles; Staller, Corey; Yu, Qingsong; Chen, Meng; Wang, Yong

    2013-01-01

    The objective of this study is to evaluate and verify the effectiveness of plasma treatment for improving adhesive/dentin interfacial bonding by performing micro-tensile bond strength (μTBS) test using the same-tooth controls and varying cross-sectional surface areas. Extracted unerupted human third molars were used by removing the crowns to expose the dentin surface. For each dentin surface, one half of it was treated with a non-thermal argon plasma brush, while another half was shielded with glass slide and used as untreated control. Adper Single Bond Plus adhesive and Filtek Z250 dental composite were then applied as directed. The teeth thus prepared were further cut into micro-bar specimens with cross-sectional size of 1×1 mm2, 1×2 mm2 and 1×3 mm2 for μTBS test. The test results showed that plasma treated specimens gave substantially stronger adhesive/dentin bonding than their corresponding same tooth controls. As compared with their untreated controls, plasma treatment gave statistically significant higher bonding strength for specimens having cross-sectional area of 1×1 mm2 and 1×2 mm2, with mean increases of 30.8% and 45.1%, respectively. Interface examination using optical and electron microscopy verified that plasma treatment improved the quality of the adhesive/dentin interface by reducing defects/voids and increasing the resin tag length in dentin tubules. PMID:23841788

  6. 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.

  7. 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

  8. Ultrastructural examination of one-step self-etch adhesive bonded primary sound and caries-affected dentin

    PubMed Central

    HOSOYA, YUMIKO; TAY, FRANKLIN R.; GARCÍA-GODOY, FRANKLIN; PASHLEY, DAVID H.

    2013-01-01

    Purpose This study examined the ultrastructure and silver nanoleakage of the resin-dentin interfaces in sound and caries-affected primary tooth dentin bonded with a 4-META one-step self-etch adhesive. Materials and Methods Each of five sound and carious primary molars was bonded with Hybrid Bond. Resin-dentin interfaces were observed with TEM micrographs obtained from silver-impregnated, unstained and undemineralized sections of bonded sound and caries-affected primary dentin, and stained and demineralized sections of bonded sound primary dentin with silver impregnation. Results For sound dentin, silver nanoleakage was observed extensively in the patent dentinal tubules, within the dentin beneath the hybrid layer, within the hybrid layer in some specimens, and as water trees that partially protruded into the overlying adhesive layer. The hybrid layer was about 1 μm thick. Smear plugs in the dentinal tubules and smear on the ground dentin protruded in the hybrid layer. Remnants of demineralized smear were observed overlying adhesive layer. For caries-affected dentin, the hybrid layer was obscure. Dentinal tubules were occluded with mineral deposits. There were no water trees or nanoleakage in the adhesive layer or hybrid layer. However, smear remnants were observed in adhesive layer and heavily silver deposits were observed in the highly porous underlying caries-affected dentin. PMID:19146129

  9. Effects of simplified ethanol-wet bonding technique on immediate bond strength with normal versus caries-affected dentin

    PubMed Central

    Aggarwal, Vivek; Singla, Mamta; Sharma, Ritu; Miglani, Sanjay; Bhasin, Saranjit Singh

    2016-01-01

    Aim: The aim of the present study was to evaluate whether the use of simplified ethanol-wet bonding (EWB) technique improved the immediate microtensile bond strength (μTBS) between resin composite and caries-affected dentin (CAD). Materials and Methods: Twenty-four extracted carious human permanent molars were sectioned to expose the carious lesion. The carious dentin was excavated until CAD was exposed. The samples were divided into two groups: water-wet bonding with Adper Scotchbond Multi-Purpose and a simplified EWB (three 100% ethanol applications for 30 s each), followed by application of an experimental hydrophobic primer and restoration. The samples were vertically sectioned to produce 1 mm × 1 mm thick slabs. The normal dentin (ND) slabs and CAD slabs were identified and were subjected to μTBS evaluation. Slabs from four teeth (two from each group) were evaluated under microscope. Data were analyzed using two-way ANOVA and post hoc Holm–Sidak test at P < 0.05. Results: EWB improved the μTBS in ND but not in CAD group. The dentinal tubules in CAD group showed sclerotic activity with minimal or no hybrid layer. Conclusions: Simplified ethanol bonding does not improve the bond strength in CAD. PMID:27656059

  10. Near tubule and intertubular bovine detin mapped at the 250 nm level.

    SciTech Connect

    Stock, S.R.; Veis, A.; Telser, A.; Cai, Z.

    2011-11-01

    In this study, simultaneous diffraction and fluorescence mapping with a (250 nm){sup 2}, 10.1 keV synchrotron X-ray beam investigated the spatial distribution of carbonated apatite (cAp) mineral and elemental Ca (and other cations including Zn) around dentin tubules. In 1 {mu}m thick sections of near-pulp root dentin, where peritubular dentin (PTD) is newly forming, high concentrations of Zn, relative to those in intertubular dentin (ITD), were observed adjacent to and surrounding the tubule lumens. Some but not all tubules exhibited hypercalcified collars (high Ca signal relative to the surrounding ITD), and, when present, the zone of high Ca did not extend around the tubule. Diffraction rings from cAp 00.2 and 11.2 + 21.1 + 30.0 reflections were observed, and cAp was the only crystal phase detected. Profiles of Ca, Zn and cAp diffracted intensities showed the same transitions from solid to tubule lumen, indicating the same cAp content and organization in ITD far from the tubules and adjacent to them. Further, the matching Ca and diffraction profiles demonstrated that all of the Ca is in cAp or that any noncrystalline Ca was uniformly distributed throughout the dentin. Variation of 00.2 and 11.2 + 21.1 + 30.0 diffracted intensity was consistent with the expected biaxial crystallographic texture. Extension of X-ray mapping from near 1 {mu}m resolution to the 250 nm level, performed here for dentin and its tubules, will provide new understanding of other mineralized tissues.

  11. Comparative evaluation of the effect of different bonding agents on the ultramorphology of primary tooth dentin and the resin dentin interface

    PubMed Central

    Vashisth, Pallavi; Goswami, Mousumi; Mittal, Mudit; Chaudhary, Seema

    2012-01-01

    Aim: To analyze and compare the changes in the ultramorphology of dentin in primary teeth using different bonding agents and to study the resin/dentin interface produced by them. Materials and Methods: Occlusal surfaces of 50 extracted human deciduous teeth were grounded to expose the dentin. The teeth were divided into two groups (A) For viewing surface morphology- 18 teeth divided into four groups: (a) for viewing dentinal morphology (3 teeth), (b) Scotchbond multi-purpose (5 teeth), (c) Adhe SE (5 teeth), (d) Futurabond (5 teeth). (B) For viewing interfacial morphology- 32 teeth divided into four groups with 8 teeth each: (a) Scotch Bond Multipurpose (3M, ESPE),), (b) Adhe Se (Vivadent), (c) Optibond All-in-One (Kerr), (d) Futurabond NR (VOCO, Cuxhaven, Germany). The adhesives were applied to each group following the manufacturer's instruction. All the samples were then prepared for viewing under SEM. Results: The photographs were graded using a four-step (0-3) scale method proposed by Ferrari et al. For Scotchbond, 12 (75%) were graded as 2 Grade 3 was observed in only 1 observation in the entire lot of materials. The results obtained for Adhe SE and Optibond AIO were similar, i.e. in 5 (31.25%) observations each the scores were 0 and in 11 (68.75%) observations each the scores were 1. In case of Futurabond, 3 (18.75%) observations were graded as 0 and 13 (81.25%) were graded as 1, thus showing a mean score of 0.81±0.40. Conclusion: Three- step bonding agent results in the complete removal of smear layer. While the self- etch approach is not efficient in removing the smear layer and opening of the dentinal tubules. The longest resin tags with lateral branches were seen in two groups- Scotch bond multipurpose and Optibond FL. PMID:23112484

  12. A description of chloride cell and kidney tubule alterations in the flatfish Solea senegalensis exposed to moderately contaminated sediments from the Sado estuary (Portugal)

    NASA Astrophysics Data System (ADS)

    Costa, Pedro M.; Caeiro, Sandra; Diniz, Mário S.; Lobo, Jorge; Martins, Marta; Ferreira, Ana M.; Caetano, Miguel; Vale, Carlos; DelValls, T. Ángel; Costa, M. Helena

    2010-11-01

    The effects of sediment-bound contaminants on kidney and gill chloride cells were surveyed in juvenile Solea senegalensis exposed to fresh sediments collected from three distinct sites of the Sado Estuary (Portugal) in a 28-day laboratorial assay. Sediments were analyzed for metallic contaminants, polycyclic aromatic hydrocarbons and organochlorines as well as for total organic matter, redox potential and fine fraction. The potential for causing adverse biological effects of each surveyed sediment was assessed by comparison of contaminant levels to available guidelines for coastal sediments, namely the Threshold Effects Level ( TEL) and the Probable Effects Level ( PEL). The Sediment Quality Guideline Quotient indices ( SQGQ) were calculated to compare the overall contamination levels of the three stations. A qualitative approach was employed to analyze the histo/cytopathological traits in gill chloride cells and body kidney of fish exposed to each tested sediment for 0, 14 and 28 days. The results showed that sediment contamination can be considered low to moderate and that the least contaminated sediment (from a reference site, with the lowest SQGQ) caused lesser changes in the surveyed organs. However, the most contaminated sediment (by both metallic and organic xenobiotics, with highest SQGQ) was neither responsible for the highest mortality nor for the most pronounced lesions. Exposure to the sediment presenting an intermediate SQGQ, essentially contaminated by organic compounds, caused the highest mortality (48%) and the most severe damage to kidneys, up to full renal necrosis. Chloride cell alterations were similar in fish exposed to the two most contaminated sediments and consisted of a pronounced cellular hypertrophy, likely involving fluid retention and loss of mitochondria. It can be concluded that sediment contamination considered to be low or moderate may be responsible for severe injury to cells and parenchyma involved in the maintenance of osmotic

  13. Nanocapillarity in fullerene tubules

    NASA Astrophysics Data System (ADS)

    Pederson, Mark R.; Broughton, Jeremy Q.

    1992-11-01

    Fullerene tubules are shown to be highly polarizable ``molecular straws'' capable of ingesting dipolar molecules. Local-density-functional calculations on HF molecules within a finite-length tubule, of size 144 atoms, demonstrate this effect. The energy of incarceration is several times the thermal ambient at room temperature. These calculations, now feasible on desktop workstations, open the way to the study of nanoscale capillarity and to, perhaps, precise control over shielding of specific ``guest'' compounds from external electric and magnetic fields.

  14. Mechanism of action of a desensitizing fluoride toothpaste delivering calcium and phosphate ingredients in the treatment of dental hypersensitivity. Part III: Prevention of dye penetration through dentin vs a calcium- and phosphate-free control.

    PubMed

    Winston, Anthony E; Charig, Andrew J; Thong, Stephen

    2010-01-01

    It is generally accepted that the pain of dental hypersensitivity resulting from gum recession is from the movement of fluid within the exposed tubules of dentin, causing changes in pressure on the nerve within the pulpal cavity. One method of treating hypersensitivity is to occlude the tubules, preventing fluid movement. This article discusses the use of a dye penetration technique, which establishes this mechanism of action for a desensitizing fluoride toothpaste containing calcium and phosphate. Two groups of intact teeth were perfectly sealed with enamel paint. Windows 100-micro to 200-micro deep were opened on opposite sides of each tooth at the dentin-enamel junction and briefly etched using 20% polyacrylic acid. One batch of teeth was treated eight times for 30 mins each with a 1:3 slurry of the desensitizing toothpaste and another set with a similar slurry prepared from a calcium- and phosphate-free control. A 0.85% aqueous solution of acid red fuchsin dye was applied to each window and allowed to dry. After a brief rinse, the teeth were sectioned across the windows. Almost no dye penetration was seen in teeth treated with the desensitizing toothpaste; however, extensive penetration through the dentin was visible in the control-treated teeth. The differences in dye penetration for the two sets of teeth were significant by both subjective (P < .001) and objective (P < .01) measures. Tubule occlusion because of calcium and phosphate ions from the desensitizing toothpaste accounts for its tooth desensitizing efficacy.

  15. Current status of dentin adhesive systems.

    PubMed

    Leinfelder, K F

    1998-12-01

    Undoubtedly, dentin bonding agents have undergone a major evolution during the last several years. The shear bond strength of composite resin to the surface of dentin is actually greater than the inherent strength of the dentin itself under well-controlled conditions. No longer must the clinician depend only upon the bonding to enamel as the sole bonding mechanism. Bonding to both types of dental structure permits even better reinforcement of the tooth itself. Perhaps even more important than the high level of bonding exhibited by the current dentin adhesives is their ability to seal the dentin. So effective is this sealing capability that it is now possible to protect the pulpal tissue from microbial invasion through the dentinal tubules. Further, by enclosing the odontoblastic processes and preventing fluid flow, the potential for postoperative sensitivity is diminished considerably. In fact, so evolutionary is the concept of bonding that the procedures associated with the restoration of teeth has changed dramatically. Undoubtedly, far greater improvements can be anticipated in the future.

  16. Effect of periodontal root planing on dentin permeability.

    PubMed

    Fogel, H M; Pashley, D H

    1993-10-01

    The purpose of this study was to quantitate the effects of root planing on the permeability of human root dentin in vitro. Unerupted 3rd molars were used. The crowns were removed and longitudinal slices made of the root. The hydraulic conductance of the root dentin was measured before and after root planing, acid etching and potassium oxalate application using a fluid filtration method. The results showed that root planing creates a smear layer that reduces the permeability of the underlying dentin. However, this smear layer is acid labile. Thus, root planing may ultimately cause increased dentin permeability and the associated sequelae of sensitive dentin, bacterial invasion of tubules, reduced periodontal reattachment and pulpal irritation.

  17. Effects of a Dicalcium and Tetracalcium Phosphate-Based Desensitizer on In Vitro Dentin Permeability.

    PubMed

    Zhou, Jianfeng; Chiba, Ayaka; Scheffel, Debora L S; Hebling, Josimeri; Agee, Kelli; Niu, Li-Na; Tay, Franklin R; Pashley, David H

    2016-01-01

    The present study evaluated the effectiveness of a dicalcium and tetracalcium phosphate-based desensitizer in reducing dentin permeability in vitro. Dentin fluid flow was measured before and after treatment of dentin with patent dentinal tubules using 1 or 3 applications of the dicalcium and tetracalcium phosphate containing agent TeethmateTM (TM) and comparing the results with two sodium fluoride varnishes VellaTM (VLA) and VanishTM (VAN), after storage in artificial saliva for 24 h, 48 h and 7 days. Significant differences were observed among the 4 methods employed for reducing dentin permeability (p < 0.001) and the 3 post-treatment times (p < 0.001). VLA and VAN never achieved 50% permeability reductions consistently in any of the 3 time periods. Only the calcium phosphate-based desensitizer applied for 3 times consistently reduced dentin permeability by 50% after 24 h. When applied once, the permeability reduction of TM increased progressively over the 3 time periods. After 7 days, only one and three applications of the calcium phosphate-based desensitizer consistently reduced dentin permeability by more than 50%. Permeability reductions corresponded well with scanning electron microscopy examination of dentinal tubule orifice occlusion in dentin specimens treated with the agents. Overall, the dicalcium and tetracalcium phosphate-based desensitizer is effective in reducing dentin permeability via a tubule occlusion mechanism. The ability of the agent to reduce dentin permeability renders it to be potentially useful as a clinical dentin desensitizing agent, which has to be confirmed in future clinical studies. By contrast, the two sodium fluoride varnishes are not effective in dentin permeability reduction and should be considered as topical fluoride delivering agents rather than tubular orifice-blocking agents.

  18. Effects of a Dicalcium and Tetracalcium Phosphate-Based Desensitizer on In Vitro Dentin Permeability

    PubMed Central

    Zhou, Jianfeng; Chiba, Ayaka; Scheffel, Debora L. S.; Hebling, Josimeri; Agee, Kelli; Niu, Li-na; Tay, Franklin R.; Pashley, David H.

    2016-01-01

    The present study evaluated the effectiveness of a dicalcium and tetracalcium phosphate-based desensitizer in reducing dentin permeability in vitro. Dentin fluid flow was measured before and after treatment of dentin with patent dentinal tubules using 1 or 3 applications of the dicalcium and tetracalcium phosphate containing agent TeethmateTM (TM) and comparing the results with two sodium fluoride varnishes VellaTM (VLA) and VanishTM (VAN), after storage in artificial saliva for 24 h, 48 h and 7 days. Significant differences were observed among the 4 methods employed for reducing dentin permeability (p < 0.001) and the 3 post-treatment times (p < 0.001). VLA and VAN never achieved 50% permeability reductions consistently in any of the 3 time periods. Only the calcium phosphate-based desensitizer applied for 3 times consistently reduced dentin permeability by 50% after 24 h. When applied once, the permeability reduction of TM increased progressively over the 3 time periods. After 7 days, only one and three applications of the calcium phosphate-based desensitizer consistently reduced dentin permeability by more than 50%. Permeability reductions corresponded well with scanning electron microscopy examination of dentinal tubule orifice occlusion in dentin specimens treated with the agents. Overall, the dicalcium and tetracalcium phosphate-based desensitizer is effective in reducing dentin permeability via a tubule occlusion mechanism. The ability of the agent to reduce dentin permeability renders it to be potentially useful as a clinical dentin desensitizing agent, which has to be confirmed in future clinical studies. By contrast, the two sodium fluoride varnishes are not effective in dentin permeability reduction and should be considered as topical fluoride delivering agents rather than tubular orifice-blocking agents. PMID:27359118

  19. 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

  20. 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 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.

  1. Contributions of Aging to the Fatigue Crack Growth Resistance of Human Dentin

    PubMed Central

    Ivancik, Juliana; Majd, Hessam; Bajaj, Devendra; Romberg, Elaine; Arola, Dwayne

    2012-01-01

    An evaluation of the fatigue crack resistance of human dentin was conducted to identify the degree of degradation that arises with aging and the dependency on tubule orientation. Fatigue crack growth was achieved in specimens of coronal dentin through application of Mode I cyclic loading and over clinically relevant lengths (0 ≤ a ≤ 2 mm). The study considered two directions of cyclic crack growth in which the crack was either in-plane (0°) or perpendicular (90°) to the dentin tubules. Results showed that regardless of tubule orientation, aging of dentin is accompanied by a significant reduction in the resistance to the initiation of fatigue crack growth, as well as a significant increase in the rate of incremental extension. Perpendicular to the tubules, the fatigue crack exponent increased significantly (from m=14.2±1.5 to 24.1±5.0), suggesting an increase in brittleness of the tissue with age. For cracks extending in plane with the tubules, the fatigue crack growth exponent does not change significantly with patient age (from m=25.4±3.03 to 22.9±5.3), but there is a significant increase in the incremental crack growth rate. Regardless of age, coronal dentin exhibits the lowest resistance to fatigue crack growth perpendicular to the tubules. While there are changes in the cyclic crack growth rate and mechanisms of cyclic extension with aging, this tissue maintains its anisotropy. PMID:22484693

  2. Sodium hypochlorite alterations of dentin and dentin collagen

    NASA Astrophysics Data System (ADS)

    Marshall, G. W.; Yücel, N.; Balooch, M.; Kinney, J. H.; Habelitz, S.; Marshall, S. J.

    2001-10-01

    NaOCl aq is used as a cleansing and non-specific deproteinizing agent in endodontic treatment, as a component of new chemomechanical caries treatment, and is under study for its alterations of dentin bonding characteristics. We sought to determine the microstructural and nanomechanical changes with such treatments and to test if NaOCl aq removed dentin collagen without microstructural or nanomechanical alteration of underlying mineralized dentin. Polished human dentin disks were prepared with a double reference technique that allowed changes to be determined following 10% citric acid etching for 15 s and subsequent treatment of the etched and unetched portions of the sample with 6.5% NaOCl aq, using atomic force microscopy (AFM) (Nanoscope III, Digital Instruments, Santa Barbara, CA). Images and measurements were made at intervals up to 1800 s. A Triboscope (Hysitron, Minneapolis, MN) on the AFM was used to measure nanohardness and the reduced elastic modulus. The double reference method allowed measurements immediately following etching and at intervals during deproteinization. Etching caused deep peritubular dentin removal and a small depth change of hydrated intertubular dentin as mineral was removed and left a remnant collagen matrix. NaOCl aq removed collagen over time, during which individual fibrils could be resolved; the underlying mineralized dentin was left with a unique porous surface containing numerous channels that are not normally observed in etched or fractured dentin. This could provide an attractive bonding substrate because of the increased surface area and high mineral content, if toughness is not reduced too much. Nanomechanical measurements showed that the reduced elastic modulus and hardness were 75% of original values after removal of the exposed collagen. Current dentin bonding systems rely on hybrid layer formation in which hydrophilic primers/polymers penetrate the opened collagen matrix exposed by etching. However some research suggests

  3. Dentin bonding-variables related to the clinical situation and the substrate treatment.

    PubMed

    Perdigão, Jorge

    2010-02-01

    The wetness of dentin surfaces, the presence of pulpal pressure, and the thickness of dentin are extremely important variables during bonding procedures, especially when testing bond strength of adhesive materials in vitro with the intention of simulating in vivo conditions. The ultimate goal of a bonded restoration is to attain an intimate adaptation of the restorative material with the dental substrate. This task is difficult to achieve as the bonding process is different for enamel and for dentin-dentin is more humid and more organic than enamel. While enamel is predominantly mineral, dentin contains a significant amount of water and organic material, mainly type I collagen. This humid and organic nature of dentin makes this hard tissue very challenging to bond to. Several other substrate-related variables may affect the clinical outcome of bonded restorations. Bonding to caries-affected dentin is hampered by its lower hardness and presence of mineral deposits in the tubules. Non-carious cervical areas contain hypermineralized dentin and denatured collagen, which is not the ideal combination for a bonding substrate. Physiological transparent root dentin forms without trauma or caries lesion as a natural part of aging. Similar to the transparent dentin observed underneath caries lesions, the tubule lumina become filled with mineral from passive chemical precipitation, making resin hybridization difficult. An increase in number of tubules with depth and, consequently, increase in dentin wetness, make bonding to deeper dentin more difficult than to superficial dentin. While the application of acidic agents open the pathway for the diffusion of monomers into the collagen network, it also facilitates the outward seepage of tubular fluid from the pulp to the dentin surface, deteriorating the bonding for some of the current adhesives. Some dentin desensitizers have shown some promise as they can block dentinal tubules to treat and prevent sensitivity and simultaneously

  4. Age-related ransparent root dentin: mineral concentration,crystallite size and mechanical properties

    SciTech Connect

    Kinney, John H.; Nalla, Ravi K.; Pople, John A.; Breunig, Tom M.; Ritchie, Robert O.

    2004-12-29

    Many fractures occur in teeth that have been altered, forexample restored or endodontically repaired. It is therefore essential toevaluate the structure and mechanical properties of these altereddentins. One such altered form of dentin is transparent (sometimes calledsclerotic) dentin, which forms gradually with aging. The present studyfocuses on differences in the structure and mechanical properties ofnormal versus transparent dentin. The mineral concentration, as measuredby X-ray computed microtomography, was signifcantly higher in transparentdentin, the elevated concentration being consistent with the closure ofthe tubule lumens. Crystallite size, as measured by small angle X-rayscattering, was slightly smaller in transparent dentin, although theimportance of this ending requires further study. The elastic propertieswere unchanged by transparency; however, transparent dentin, unlikenormal dentin, exhibited almost no yielding before failure. In addition,the fracture toughness was lowered by roughly 20 percent while thefatigue lifetime was deleteriously affected at high stress levels. Theseresults are discussed in terms of the altered microstructure oftransparent dentin.

  5. Essential role of Osterix for tooth root but not crown dentin formation

    PubMed Central

    Zhang, Hua; Jiang, Yong; Qin, Chunlin; Liu, Ying; Ho, Sunita P.; Feng, Jian Q.

    2015-01-01

    Tooth is made of crown and root. It is widely believed that dentin formation in crown and root uses the same regulatory mechanism. However, identification of NFIC’s unique function in determining root but not crown dentin formation challenges the old thought. In searching for the target molecules downstream of NFIC, we unexpectedly found a sharp reduction of OSX (osterix), the key transcription factor in skeleton formation, in the Nfic knockout (KO) tooth root. We then demonstrated a dose-dependent increase of Osx in the odontoblast cell line due to a transient transfection of Nfic expression plasmid. Studies of global and conditional Osx KO mice revealed no apparent changes in the crown dentin tubules and dentin matrix. However, the OSX conditional KO mice (crossed to the 2.3 kb Col 1-Cre) displayed an increase in cell proliferation but great decreases in expressions of root dentin matrix proteins (DMP1 and DSPP), leading to an inhibition in odontoblast differentiation, and short thin root dentin with few dentin tubules. Compared to the Nfic KO tooth, which contains essentially no dentin tubules and remains in a “root-less” status at adult stages, the Osx cKO root phenotype had partially improved at the late stage, indicating that other factors can compensate for OSX function. Thus, we conclude that OSX, one of the key downstream molecules of NFIC, plays a critical role in root, but not crown, formation. PMID:25349111

  6. Growth Factor Liberation and DPSC Response Following Dentine Conditioning.

    PubMed

    Sadaghiani, L; Gleeson, H B; Youde, S; Waddington, R J; Lynch, C D; Sloan, A J

    2016-10-01

    Liberation of the sequestrated bioactive molecules from dentine by the action of applied dental materials has been proposed as an important mechanism in inducing a dentinogenic response in teeth with viable pulps. Although adhesive restorations and dentine-bonding procedures are routinely practiced, clinical protocols to improve pulp protection and dentine regeneration are not currently driven by biological knowledge. This study investigated the effect of dentine (powder and slice) conditioning by etchants/conditioners relevant to adhesive restorative systems on growth factor solubilization and odontoblast-like cell differentiation of human dental pulp progenitor cells (DPSCs). The agents included ethylenediaminetetraacetic acid (EDTA; 10%, pH 7.2), phosphoric acid (37%, pH <1), citric acid (10%, pH 1.5), and polyacrylic acid (25%, pH 3.9). Growth factors were detected in dentine matrix extracts drawn by EDTA, phosphoric acid, and citric acid from powdered dentine. The dentine matrix extracts were shown to be bioactive, capable of stimulating odontogenic/osteogenic differentiation as observed by gene expression and phenotypic changes in DPSCs cultured in monolayer on plastic. Polyacrylic acid failed to solubilize proteins from powdered dentine and was therefore considered ineffective in triggering a growth factor-mediated response in cells. The study went on to investigate the effect of conditioning dentine slices on growth factor liberation and DPSC behavior. Conditioning by EDTA, phosphoric acid, and citric acid exposed growth factors on dentine and triggered an upregulation in genes associated with mineralized differentiation, osteopontin, and alkaline phosphatase in DPSCs cultured on dentine. The cells demonstrated odontoblast-like appearances with elongated bodies and long extracellular processes extending on dentine surface. However, phosphoric acid-treated dentine appeared strikingly less populated with cells, suggesting a detrimental impact on cell

  7. Interaction between bioactive glasses and human dentin.

    PubMed

    Efflandt, S E; Magne, P; Douglas, W H; Francis, L F

    2002-06-01

    This study explores the interaction between bioactive glasses and dentin from extracted human teeth in simulated oral conditions. Bioactive glasses in the Na(2)O-CaO-P(2)O(5)-SiO(2) and MgO-CaO-P(2)O(5)-SiO(2) systems were prepared as polished disks. Teeth were prepared by grinding to expose dentin and etching with phosphoric acid. A layer of saliva was placed between the two, and the pair was secured with an elastic band and immersed in saliva at 37 degrees C for 5, 21 or 42 days. The bioactive glasses adhered to dentin, while controls showed no such interaction. A continuous interface between the bioactive glass and dentin was imaged using cryogenic-scanning electron microscopy (SEM). However, after alcohol dehydration and critical point drying, fracture occurred due to stresses from dentin shrinkage. SEM investigations showed a microstructurally different material at the fractured interface. Chemical analyses revealed that ions from the glass penetrated into the dentin and that the surface of the glass in contact with the dentin was modified. Microdiffractometry showed the presence of apatite at the interface. Bonding appears to be due to an affinity of collagen for the glass surface and chemical interaction between the dentin and glass, leading to apatite formation at the interface.

  8. Effects of different desensitizing treatments on root dentin permeability.

    PubMed

    Rosa, Raydsa Raíssa Moura; Calazans, Francielle Karoline Santos; Nogueira, Ruchele Dias; Lancellotti, Ailla Carla Rocha Acosta; Gonçalves, Luciano de Sousa; Geraldo-Martins, Vinícius Rangel

    2016-10-10

    The objective of this study was to evaluate the effects of diode laser and a desensitizing dentifrice on dentin permeability. Fifty-two root dentin fragments were obtained (5 × 5mm) and treated with 24% EDTA gel. The samples were divided into 4 groups (n = 13): G1, control (no treatment); G2, diode laser (λ = 908 nm, 1.5 W, continuous mode, 20s); G3, application of abrasive dentifrice for 1 minute (Elmex Sensitive Professional (International Gaba); and G4, application of abrasive dentifrice for 1 minute followed by irradiation with diode laser. Ten samples per group were immersed in 2% methylene blue solution for 4h. The specimens were washed, longitudinally sectioned, observed under optical microscopy, photographed and assessed based on the degree of dye leakage. The remaining samples were observed under scanning electron microscopy (SEM). The leakage data were subjected to ANOVA test, followed by Tukey's t-test (α = 5%). Groups 2, 3 and 4 showed less dye penetration than the control group (p < 0.05), but were similar among each other. SEM images showed that dentinal tubules were open in G1, and fused and occluded in G2. Group 3 showed dentinal tubules that were occluded by the metal ions from the toothpaste. G4 presented similar characteristics to G3, and the presence of fused dentin. The diode laser and the dentifrice were effective in reducing dentinal permeability, and the combination of the two treatments did not show better results than either one used alone.

  9. 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.

  10. The Role of Host-derived Dentinal Matrix Metalloproteinases in Reducing Dentin Bonding of Resin Adhesives

    PubMed Central

    Zhang, Shan-chuan; Kern, Matthias

    2009-01-01

    Dentin matrix metalloproteinases (MMPs) are a family of host-derived proteolytic enzymes trapped within mineralized dentin matrix, which have the ability to hydrolyze the organic matrix of demineralized dentin. After bonding with resins to dentin there are usually some exposed collagen fibrils at the bottom of the hybrid layer owing to imperfect resin impregnation of the demineralized dentin matrix. Exposed collagen fibrils might be affected by MMPs inducing hydrolytic degradation, which might result in reduced bond strength. Most MMPs are synthesized and released from odontoblasts in the form of proenzymes, requiring activation to degrade extracellular matrix components. Unfortunately, they can be activated by modern self-etch and etch-and-rinse adhesives. The aim of this review is to summarize the current knowledge of the role of dentinal host-derived MMPs in dentin matrix degradation. We also discuss various available MMP inhibitors, especially chlorhexidine, and suggest that they could provide a potential pathway for inhibiting collagen degradation in bonding interfaces thereby increasing dentin bonding durability. PMID:20690420

  11. The role of host-derived dentinal matrix metalloproteinases in reducing dentin bonding of resin adhesives.

    PubMed

    Zhang, Shan-chuan; Kern, Matthias

    2009-12-01

    Dentin matrix metalloproteinases (MMPs) are a family of host-derived proteolytic enzymes trapped within mineralized dentin matrix, which have the ability to hydrolyze the organic matrix of demineralized dentin. After bonding with resins to dentin there are usually some exposed collagen fibrils at the bottom of the hybrid layer owing to imperfect resin impregnation of the demineralized dentin matrix. Exposed collagen fibrils might be affected by MMPs inducing hydrolytic degradation, which might result in reduced bond strength. Most MMPs are synthesized and released from odontoblasts in the form of proenzymes, requiring activation to degrade extracellular matrix components. Unfortunately, they can be activated by modem self-etch and etch-and-rinse adhesives. The aim of this review is to summarize the current knowledge of the role of dentinal host-derived MMPs in dentin matrix degradation. We also discuss various available MMP inhibitors, especially chlorhexidine, and suggest that they could provide a potential pathway for inhibiting collagen degradation in bonding interfaces thereby increasing dentin bonding durability.

  12. Crystallographic Texture and Elemental Composition Mapped in Bovine Root Dentin at the 200 nm Level

    PubMed Central

    Deymier-Black, A. C.; Veis, A.; Cai, Z.; Stock, S. R.

    2015-01-01

    Summary The relationship between the mineralization of peritubular dentin (PTD) and intertubular dentin (ITD) is not well understood. Tubules are quite small, diameter ~2 μm, and this makes the near-tubule region of dentin difficult to study. Here, advanced characterization techniques are applied in a novel way to examine what organic or nanostructural signatures may indicate the end of ITD or the beginning of PTD mineralization. X-ray fluorescence intensity (Ca, P, and Zn) and X-ray diffraction patterns from carbonated apatite (cAp) were mapped around dentintubules at resolutions ten times smaller than the feature size (200 nm pixels), representing a 36% increase in resolution over earlier work. In the near tubule volumes of near-pulp, root dentin, Zn intensity was higher than in ITD remote from the tubules. This increase in Zn2+, as determined by X-ray absorption near edge structure analysis, may indicate the presence of metalloenzymes or transcription factors important to ITD or PTD mineralization. The profiles of the cAp 00.2 X-ray diffraction rings were fitted with a pseudo-Voigt function, and the spatial and azimuthal distribution of these rings’ integrated intensities indicated that the cAp platelets were arranged with their c-axes aligned tangential to the edge of the tubule lumen. This texture was continuous throughout the dentin indicating a lack of structural difference between in the Zn rich near-tubular region and the remote ITD. PMID:23630059

  13. Chemical and morphological changes in human dentin after Er:YAGlaser irradiation: EDS and SEM analysis.

    PubMed

    Contreras-Arriaga, Belinda; Rodríguez-Vilchis, Laura Emma; Contreras-Bulnes, Rosalía; Olea-Mejìa, Oscar Fernando; Scougall-Vilchis, Rogelio José; Centeno-Pedraza, Claudia

    2015-11-01

    Sixty samples of human dentin were divided into six groups (n = 10) and were irradiated with Er:YAG laser at 100 mJ-19.9 J/cm(2), 150 mJ-29.8 J/cm(2), 100 mJ-35.3 J/cm(2), 150 mJ-53.0 J/cm(2), 200 mJ-70.7 J/cm(2), and 250 mJ-88.5 J/cm(2), respectively, at 7 Hz under a water spray. The atomic percentages of carbon, oxygen, magnesium, calcium, and phosphorus and the Ca-to-P molar ratio on the dentin were determined by energy dispersive X-ray spectroscopy. The morphological changes were observed using scanning electron microscopy. A paired t-test was used in statistical analysis before and after irradiation, and a one-way ANOVA was performed (P ≤ 0.05). The atomic percent of C tended to decrease in all of the groups after irradiation with statistically significant differences, O and Mg increased with significant differences in all of the groups, and the Ca-to-P molar ratio increased in groups IV, V, and VI, with statistically significant differences between groups II and VI. All the irradiated samples showed morphological changes. Major changes in the chemical composition of dentin were observed in trace elements. A significant increase in the Ca-to-P ratio was observed in the higher energy density groups. Morphological changes included loss of smear layer with exposed dentinal tubules. The changes produced by the different energy densities employed could have clinical implications, additional studies are required to clarify them.

  14. 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

  15. ON THE STIFFNESS OF DEMINERALIZED DENTIN MATRICES

    PubMed Central

    Ryou, Heonjune; Turco, Gianluca; Breschi, Lorenzo; Tay, Franklin R.; Pashley, David H.; Arola, Dwayne

    2015-01-01

    Resin bonding to dentin requires the use of self-etching primers or acid etching to decalcify the surface and expose a layer of collagen fibrils of the dentin matrix. Acid-etching reduces the stiffness of demineralized dentin from approximately 19 GPa to 1 MPa, requiring that it floats in water to prevent it from collapsing during bonding procedures. Several publications show that crosslinking agents like gluteraladehyde, carbodiimide or grape seed extract can stiffen collagen and improve resin-dentin bond strength. Objective The objective was to assess a new approach for evaluating the changes in stiffness of decalcified dentin by polar solvents and a collagen cross-linker. Methods Fully demineralized dentin beams and sections of etched coronal dentin were subjected to indentation loading using a cylindrical flat indenter in water, and after treatment with ethanol or ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC). The stiffness was measured as a function of strain and as a function of loading rate from 1 to 50 µm/sec. Results At a strain of 0.25% the elastic modulus of the fully demineralized dentin was approximately 0.20 MPa. It increased to over 0.90 MPa at strains of 1%. Exposure to ethanol caused an increase in elastic modulus of up to four times. Increasing the loading rate from 1 to 50 µm/sec caused an increase in the apparent modulus of up to three times in both water and ethanol. EDC treatment caused increases in the stiffness in fully demineralized samples and in acid-etched demineralized dentin surfaces in situ. Significance Changes in the mechanical behavior of demineralized collagen matrices can be measured effectively under hydration via indentation with cylindrical flat indenters. This approach can be used for quantifying the effects of bonding treatments on the properties of decalcified dentin after acid etching, as well as to follow the loss of stiffness over time due to enzymatic degradation. PMID:26747822

  16. Dentin Morphology of Root Canal Surface: A Quantitative Evaluation Based on a Scanning Electronic Microscopy Study

    PubMed Central

    Lo Giudice, Giuseppe; Cutroneo, Giuseppina; Centofanti, Antonio; Artemisia, Alessandro; Bramanti, Ennio; Militi, Angela; Rizzo, Giuseppina; Favaloro, Angelo; Irrera, Alessia; Lo Giudice, Roberto; Cicciù, Marco

    2015-01-01

    Dentin is a vital, hydrated composite tissue with structural components and properties that vary in the different topographic portions of the teeth. These variations have a significant implication for biomechanical teeth properties and for the adhesive systems utilized in conservative dentistry. The aim of this study is to analyse the root canal dentin going from coronal to apical zone to find the ratio between the intertubular dentin area and the surface occupied by dentin tubules varies. Observations were conducted on 30 healthy premolar teeth extracted for orthodontic reasons in patients aged between 10 and 14. A SEM analysis of the data obtained in different canal portions showed that, in the coronal zone, dentinal tubules had a greater diameter (4.32 μm) than the middle zone (3.74 μm) and the apical zone (1.73 μm). The average number of dentinal tubules (in an area of 1 mm2) was similar in coronal zone (46,798 ± 10,644) and apical zone (45,192 ± 10,888), while in the middle zone they were lower in number (30,940 ± 7,651). However, intertubular dentin area was bigger going from apical to coronal portion. The differences between the analysed areas must be considered for the choice of the adhesive system. PMID:26413504

  17. Effects of common dental materials used in preventive or operative dentistry on dentin permeability and remineralization.

    PubMed

    Sauro, Salvatore; Thompson, Ian; Watson, Timothy F

    2011-01-01

    The aim of this study was to evaluate the dentin remineralization induced by bioactive substances contained in common dental materials used in preventive and operative dentistry. Several materials were applied on human dentin segments. Dentin permeability was quantified using a fluid filtration system working at 20 cm H(2)O. Micro-Raman, SEM-EDX, and microhardness calculation were used to evaluate changes in the mineralization of dentin. Dentin treated with the prophylactic materials showed different dentin permeability values, in particular subsequent to immersion in remineralizing solutions (RSS). The bioactive glass (Sylc) was the only substance able to reduce dentin permeability after immersion in remineralizing solution and to show hydroxyapatite precipitation as a sign of dentin remineralization. The reduction in dentin permeability obtained after the application of the other prophylactic materials used in this study was due to the presence of the remnant material in the dentinal tubules, with no remineralization effect after storage in remineralizing solution. In conclusion, the results indicated that bioactive glass prophy powder may induce immediate remineralization of dentin.

  18. Permeability of Dentine

    PubMed Central

    Ghazali, Farid Bin Che

    2003-01-01

    This is an update on the present integrated knowledge regarding dentine permeability that assumed a role in dentine sensitivity and contribute clinically to the effective bonding properties of restorative dental materials. This paper will attempt to refer to in vivo and in vitro studies of dentine permeability and the various interrelated factors governing it. PMID:23365497

  19. Essential role of osterix for tooth root but not crown dentin formation.

    PubMed

    Zhang, Hua; Jiang, Yong; Qin, Chunlin; Liu, Ying; Ho, Sunita P; Feng, Jian Q

    2015-04-01

    Tooth is made of crown and root. It is widely believed that dentin formation in crown and root uses the same regulatory mechanism. However, identification of nuclear factor 1 C (NFIC)'s unique function in determining root but not crown dentin formation challenges the old thinking. In searching for the target molecules downstream of NFIC, we unexpectedly found a sharp reduction of osterix (OSX), the key transcription factor in skeleton formation, in the Nfic knockout (Nfic-KO) tooth root. We then demonstrated a dose-dependent increase of Osx in the odontoblast cell line due to a transient transfection of Nfic expression plasmid. Studies of global and conditional Osx-KO mice revealed no apparent changes in the crown dentin tubules and dentin matrix. However, the OSX conditional KO (cKO) mice (crossed to the 2.3-kb collagen type 1 [Col1]-Cre) displayed an increase in cell proliferation but great decreases in expressions of root dentin matrix proteins (dentin matrix protein 1 [DMP1] and dentin sialophosphoprotein [DSPP]), leading to an inhibition in odontoblast differentiation, and short, thin root dentin with few dentin tubules. Compared to the Nfic-KO tooth, which contains essentially no dentin tubules and remains in a "root-less" status at adult stages, the Osx-cKO root phenotype had partially improved at the late stage, indicating that other factors can compensate for OSX function. Thus, we conclude that OSX, one of the key downstream molecules of NFIC, plays a critical role in root, but not crown, formation.

  20. 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

  1. Influence of sodium chloride content in electrolyte solution on electrochemical impedance measurements of human dentin

    PubMed Central

    Eldarrat, Aziza; High, Alec; Kale, Girish

    2017-01-01

    Background: The aim of this study was to investigate the influence of sodium chloride (NaCl) content in electrolyte solution on electrochemical impedance measurements of human dentin by employing electrochemical impedance spectroscopy. Materials and Methods: Dentin samples were prepared from extracted molars. Electrochemical impedance measurements were carried out over a wide frequency range (0.01Hz-10MHz). After measurements, samples were characterized using scanning electron microscopy. Results: Electrochemical impedance measurements showed that the mean values of dentin electrical resistance were 4284, 2062, 1336, 53 and 48kΩ at different NaCl contents in electrolyte solution. One-way ANOVA test of mean values of dentin electrical resistance revealed a significant difference (P < 0.0001) as a function of NaCl content in electrolyte solution. Comparing electrical resistance values of dentin samples at 0.05% w/v and 0.9% w/v concentrations were found to be significantly different (P < 0.05 at 95% confidence level). Scanning electron microscopy revealed structure of dentin sample with intertubular dentin matrix and distribution of patent dentinal tubules. Conclusion: This in vitro study indicated, through electrochemical impedance spectroscopy measurements, that electrical resistance of dentin was affected by the concentration of NaCl in electrolyte solution. It is clear from the current study that NaCl concentration in electrolyte solution has a marked influence on dentin electrical resistance. Therefore, this baseline data need to be considered in any future study on dental samples. PMID:28348614

  2. 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

  3. Dentinal hypersensitivity: A comparative clinical evaluation of CPP-ACP F, sodium fluoride, propolis, and placebo

    PubMed Central

    Madhavan, Souparna; Nayak, Moksha; Shenoy, Amarnath; Shetty, Rajesh; Prasad, Krishna

    2012-01-01

    Background: Dentine hypersensitivity is a transient condition that often resolves with the natural sclerotic obturation of dentinal tubules. A potent topically applied in-office desensitizing treatment is indicated as the choice of treatment when dentine hypersensitivity is localized to one or two teeth. Aim: The present study aimed to evaluate and compare the clinical efficiency of CPP-ACP F, sodium fluoride, propolis, and distilled water that was used as placebo in treating dentinal hypersensitivity. Materials and Methods: 120 patients aged 20–40 years reporting with dentinal hypersensitivity in relation to canine, premolar and molars with erosion, abrasion, and gingival recession were randomly assigned to four groups of 30 patients each. Response to air jet and tactile stimuli were measured using visual analogue scale initially on 1st, 7th, 15th, 28th, 60th, and final assessment was done on the 90th day. Statistical Analysis: A statistical analysis was done using Anova test (Fischer's test) and Tukey HSD test for multicomparison. Results: The teeth treated with the test group showed decrease in the mean hypersensitivity values compared to control group, over a period of three months. The results showed propolis to be most efficient in treating dentinal hypersensitivity and CPP- ACPF showed to be the least efficient. Conclusion: All test groups were effective in reducing dentinal hypersensitivity, although they differed in rapidity of action over the period of 3 months. Further studies can be done using advanced materials and techniques. Multiple therapeutic modalities have been developed to treat dentinal hypersensitivity including products that impede nerve conduction of pain stimulus, products that mechanically occlude dentinal tubules, and calcium containing products designed to create plugs in the tubules utilizing a demineralization mechanism. PMID:23112475

  4. Crystallographic texture and elemental composition mapped in bovine root dentin at the 200 nm level.

    PubMed

    Deymier-Black, A C; Veis, A; Cai, Z; Stock, S R

    2014-01-01

    The relationship between the mineralization of peritubular dentin (PTD) and intertubular dentin (ITD) is not well understood. Tubules are quite small, diameter ∼2 µm, and this makes the near-tubule region of dentin difficult to study. Here, advanced characterization techniques are applied in a novel way to examine what organic or nanostructural signatures may indicate the end of ITD or the beginning of PTD mineralization. X-ray fluorescence intensity (Ca, P, and Zn) and X-ray diffraction patterns from carbonated apatite (cAp) were mapped around dentintubules at resolutions ten times smaller than the feature size (200 nm pixels), representing a 36% increase in resolution over earlier work. In the near tubule volumes of near-pulp, root dentin, Zn intensity was higher than in ITD remote from the tubules. This increase in Zn(2+), as determined by X-ray absorption near edge structure analysis, may indicate the presence of metalloenzymes or transcription factors important to ITD or PTD mineralization. The profiles of the cAp 00.2 X-ray diffraction rings were fitted with a pseudo-Voigt function, and the spatial and azimuthal distribution of these rings' integrated intensities indicated that the cAp platelets were arranged with their c-axes aligned tangential to the edge of the tubule lumen. This texture was continuous throughout the dentin indicating a lack of structural difference between in the Zn rich near-tubular region and the remote ITD.

  5. 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

  6. Effect of UVA-activated riboflavin on dentin bonding.

    PubMed

    Cova, A; Breschi, L; Nato, F; Ruggeri, A; Carrilho, M; Tjäderhane, L; Prati, C; Di Lenarda, R; Tay, F R; Pashley, D H; Mazzoni, A

    2011-12-01

    Recent studies have reported collagen cross-linking after exposure to riboflavin followed by ultraviolet-A (UVA) exposure. This study is the first to investigate the effect of a riboflavin-containing primer on adhesive interface stability and dentinal matrix metalloproteinase activity. Human dentin was etched with 35% phosphoric acid, treated with 0.1% riboflavin, exposed to UVA for 2 min, and bonded with a two-step etch-and-rinse adhesive. Adhesive was applied to control specimens without riboflavin/UVA. Specimens were subjected to microtensile bond strength tests and pulled to failure after storage for 24 hrs, 6 mos, or 1 yr. Interfacial nanoleakage was evaluated by light and transmission electron microscopy. To investigate dentinal matrix metalloproteinase activity, we performed correlative zymographic assays on protein extracts obtained from phosphoric-acid-etched dentin powder with or without riboflavin/UVA treatment and XP Bond. Ultraviolet-activated riboflavin treatment increased the immediate bond strength to dentin at all aging intervals (p < 0.05 vs. control) and decreased interfacial nanoleakage in aged specimens (1 yr; p < 0.05). Zymograms revealed that riboflavin/UVA pre-treatment inhibited dentinal matrix metalloproteinase activity (especially MMP-9). In conclusion, dentinal collagen cross-linking induced by riboflavin/UVA increased immediate bond strength, stabilized the adhesive interface, and inhibited dentin matrix metalloproteinases, thereby increasing the durability of resin-dentin bonds.

  7. Effect of UVA-activated Riboflavin on Dentin Bonding

    PubMed Central

    Cova, A.; Breschi, L.; Nato, F.; Ruggeri, A.; Carrilho, M.; Tjäderhane, L.; Prati, C.; Di Lenarda, R.; Tay, F.R.; Pashley, D.H.; Mazzoni, A.

    2011-01-01

    Recent studies have reported collagen cross-linking after exposure to riboflavin followed by ultraviolet-A (UVA) exposure. This study is the first to investigate the effect of a riboflavin-containing primer on adhesive interface stability and dentinal matrix metalloproteinase activity. Human dentin was etched with 35% phosphoric acid, treated with 0.1% riboflavin, exposed to UVA for 2 min, and bonded with a two-step etch-and-rinse adhesive. Adhesive was applied to control specimens without riboflavin/UVA. Specimens were subjected to microtensile bond strength tests and pulled to failure after storage for 24 hrs, 6 mos, or 1 yr. Interfacial nanoleakage was evaluated by light and transmission electron microscopy. To investigate dentinal matrix metalloproteinase activity, we performed correlative zymographic assays on protein extracts obtained from phosphoric-acid-etched dentin powder with or without riboflavin/UVA treatment and XP Bond. Ultraviolet-activated riboflavin treatment increased the immediate bond strength to dentin at all aging intervals (p < 0.05 vs. control) and decreased interfacial nanoleakage in aged specimens (1 yr; p < 0.05). Zymograms revealed that riboflavin/UVA pre-treatment inhibited dentinal matrix metalloproteinase activity (especially MMP-9). In conclusion, dentinal collagen cross-linking induced by riboflavin/UVA increased immediate bond strength, stabilized the adhesive interface, and inhibited dentin matrix metalloproteinases, thereby increasing the durability of resin-dentin bonds. PMID:21940521

  8. Visualization and quantification of healthy and carious dentin structure using confocal laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Kimura, Yuichi; Wilder-Smith, Petra B. B.; Krasieva, Tatiana B.; Arrastia-Jitosho, Anna-Marie A.; Liaw, Lih-Huei L.; Matsumoto, Koukichi; Berns, Michael W.

    1996-04-01

    In this study, a fluorescence technique was developed for visualization of dentin using confocal laser scanning microscopy (CLSM). Eighteen extracted human teeth were used: 13 showing no clinical signs of caries and 5 with visually apparent decay. Preliminary study: All teeth were horizontally sectioned to approx. 200 micrometers thickness and pre-treated as follows: no pretreatment; vacuum only; ultrasonication only; sodium hypochlorite (NaOCl) only; vacuum and NaOCl; ultrasonication and NaOCl; or vacuum, ultrasonication and NaOCl. Samples were stained with Rhodamine 123 fluorescent dye at a concentration of 10-5 M in phosphate buffer saline for 1 to 24 hours. Caries study: Dentin surfaces, some with pre-existing caries, were visualized using CLSM. Most dentin tubules in sound dentin appeared open using CLSM, but most dentin tubules in carious dentin appeared closed or narrowed. Surface images obtained using CLSM were similar to those seen by SEM, but additional subsurface imaging was possible using CLSM at depth intervals of 1 micrometers to a depth of 30 - 50 micrometers . This technique shows good potential for non-invasive surface and subsurface imaging of dentin structures.

  9. 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

  10. Digital moiré interferometric analysis on the effect of nanoparticle conditioning on the mechanical deformation in dentin

    NASA Astrophysics Data System (ADS)

    Li, Fang Chi; Kishen, Anil

    2016-02-01

    Dentin is a biological composite that forms the major bulk of tooth structure. Understanding the biomechanical response of dentin structure to forces is essential to restore the loss of mechanical integrity associated with dentin loss during disease or treatment procedures. Moiré interferometry is an optical interferometry based method, which allows wholefield, real-time analysis of dental structures with high-sensitivity. The aim of this study was to investigate the deformation gradients in dentin during function and subsequent to surface conditioning with bioactive biopolymeric nanoparticle. Slab shaped dentin specimens were prepared and a customized loading jig was used to compressively load the specimens from 10 N to 50 N. Specific regions of interest was chosen on the dentin specimens for strain analysis. The digital moiré interferometry experiments showed a distinct deformation pattern in dentin in the direction perpendicular to the dentinal tubules, which increased with increase in dentin loss. The dentin conditioned with nanoparticles did not display marked increase in strain gradients with loads. The current photomechanical experiment highlighted the impact of nanoparticle treatment to improve the mechanical integrity of dentin.

  11. Presence of matrix vesicles in the body of odontoblasts and in the inner third of dentinal tissue: A scanning electron microscopyc study

    PubMed Central

    Garcés-Ortíz, Maricela; Reyes-Gasga, José

    2013-01-01

    Objectives: 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. Study Design: Dentin tissue from 20 human bicuspids was analyzed by means of scanning electron microscopy. Results: 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. Conclusions: 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. Key words:Dentin, microvesicles, secretory vesicles, dentin formation, dentin secretion. PMID:23385510

  12. Dentin sensitivity, odontoblasts and nerves under desiccated or infected experimental cavities. A clinical, light microscopic and ultrastructural investigation.

    PubMed

    Lilja, J; Nordenvall, K J; Bränström, M

    1982-01-01

    Cavities were prepared in 35 pairs of young human premolars. One tooth in each pair served as a control. In one Series the test cavity was desiccated with compressed air for one minute. LM and TEM examination of the dentin and the adjacent pulp revealed an extensive aspiration of odontoblasts. Nerve fibers had moved 0.1 to 0.2 mm outward in the tubules. It is suggested that a streching or disruption of the nerve had occurred during desiccation. In a second Series, the test cavity was infected for 1 to 2 weeks. No nerve fibers were seen in the dentinal tubules under the cavities, only cellular remnants and some microorganisms. Despite the absence of nerves the dentin in the bottom of the infected cavities was highly sensitive to stimulation. It was concluded that the nociceptive nerves present in the adjacent inflamed pulp may be terminals, mechanosensitive in nature and that they activated by rapid outward movements of the tubules fluid.

  13. Dentine microhardness after different methods for detection and removal of carious dentine tissue

    PubMed Central

    MOLLICA, Fernanda Brandão; TORRES, Carlos Rocha Gomes; GONÇALVES, Sergio Eduardo de Paiva; MANCINI, †Maria Nadir Gasparoto

    2012-01-01

    There are several methods for identifying carious dentinal tissue aiming to avoid removal of healthy dentinal tissue. Objectives The purpose of this study was to test different methods for the detection of carious dentinal tissue regarding the amount of carious tissue removed and the remaining dentin microhardness after caries removal. Material and methods The dentin surfaces of 20 bovine teeth were exposed and half of the surface was protected with nail polish. Cariogenic challenge was performed by immersion in a demineralizing solution for 14 days. After transverse cross-section of the crown, the specimens were divided into four groups (n=10), according to the method used to identify and remove the carious tissue: "Papacárie", Caries-detector dye, DIAGNOdent and Tactile method. After caries removal, the cross-sectional surface was included in acrylic resin and polished. In a microhardness tester, the removed dentin thickness and the Vickers microhardness of the following regions were evaluated: remaining dentin after caries removal and superficial and deep healthy dentin. Results ANOVA and Tukey's test (α=0.05) were performed, except for DIAGNOdent, which did not detect the presence of caries. Results for removed dentin thickness were: "Papacárie" (424.7±105.0; a), Caries-detector dye (370.5±78.3; ab), Tactile method (322.8±51.5; bc). Results for the remaining dentin microhardness were: "Papacárie" (42.2±10.5; bc), Caries-detector dye (44.6±11.8; abc), Tactile method (24.3±9.0; d). Conclusions DIAGNOdent did not detect the presence of carious tissue; Tactile method and "Papacárie" resulted in the least and the most dentinal thickness removal, respectively; Tactile method differed significantly from "Papacárie" and Caries-detector dye in terms of the remaining dentin microhardness, and Tactile method was the one which presented the lowest microhardness values. PMID:23032207

  14. Hereditary dentine disorders: dentinogenesis imperfecta and dentine dysplasia

    PubMed Central

    Barron, Martin J; McDonnell, Sinead T; MacKie, Iain; Dixon, Michael J

    2008-01-01

    The hereditary dentine disorders, dentinogenesis imperfecta (DGI) and dentine dysplasia (DD), comprise a group of autosomal dominant genetic conditions characterised by abnormal dentine structure affecting either the primary or both the primary and secondary dentitions. DGI is reported to have an incidence of 1 in 6,000 to 1 in 8,000, whereas that of DD type 1 is 1 in 100,000. Clinically, the teeth are discoloured and show structural defects such as bulbous crowns and small pulp chambers radiographically. The underlying defect of mineralisation often results in shearing of the overlying enamel leaving exposed weakened dentine which is prone to wear. Currently, three sub-types of DGI and two sub-types of DD are recognised but this categorisation may change when other causative mutations are found. DGI type I is inherited with osteogenesis imperfecta and recent genetic studies have shown that mutations in the genes encoding collagen type 1, COL1A1 and COL1A2, underlie this condition. All other forms of DGI and DD, except DD-1, appear to result from mutations in the gene encoding dentine sialophosphoprotein (DSPP), suggesting that these conditions are allelic. Diagnosis is based on family history, pedigree construction and detailed clinical examination, while genetic diagnosis may become useful in the future once sufficient disease-causing mutations have been discovered. Differential diagnoses include hypocalcified forms of amelogenesis imperfecta, congenital erythropoietic porphyria, conditions leading to early tooth loss (Kostmann's disease, cyclic neutropenia, Chediak-Hegashi syndrome, histiocytosis X, Papillon-Lefevre syndrome), permanent teeth discolouration due to tetracyclines, Vitamin D-dependent and vitamin D-resistant rickets. Treatment involves removal of sources of infection or pain, improvement of aesthetics and protection of the posterior teeth from wear. Beginning in infancy, treatment usually continues into adulthood with a number of options including

  15. Effects of endodontic tri-antibiotic paste on bond strengths of dentin adhesives to coronal dentin

    PubMed Central

    Mirzakoucheki, Parvin; Walter, Ricardo; Jahromi, Maryam Zare; Mirsattari, Sanaz; Akbarzadeh, Navid

    2015-01-01

    Objectives The aim of this study was to evaluate the effects of tri-antibiotic paste (TAP) on microtensile bond strengths (MTBS) of dental adhesives to dentin. Materials and Methods Sixty extracted molars had their occlusal surfaces flattened to expose dentin. They were divided into two groups, i.e., control group with no dentin treatment and experimental group with dentin treatment with TAP. After 10 days, specimens were bonded using self-etch (Filtek P90 adhesive) or etch-and-rinse (Adper Single Bond Plus) adhesives and restored with composite resin. Teeth were sectioned into beams, and the specimens were subjected to MTBS test. Data were analyzed using two-way ANOVA and post hoc Tukey tests. Results There was a statistically significant interaction between dentin treatment and adhesive on MTBS to coronal dentin (p = 0.003). Despite a trend towards worse MTBS being noticed in the experimental groups, TAP application showed no significant effect on MTBS (p = 0.064). Conclusions The etch-and-rinse adhesive Adper Single Bond Plus presented higher mean bond strengths than the self-etch adhesive Filtek P90, irrespective of the group. The superior bond performance for Adper Single Bond when compared to Filtek P90 adhesive was confirmed by a fewer number of adhesive failures. The influence of TAP in bond strength is insignificant. PMID:25984475

  16. Indirect pulp capping in young patients: immunohistological study of pulp-dentin complex.

    PubMed

    Ţuculină, Mihaela Jana; Răescu, Mihaela; Dascălu, Ionela Teodora; Popescu, Mihaela; Andreescu, Claudia Florina; Dăguci, C; Cumpătă, C N; Nimigean, Vanda Roxana; Baniţă, Ileana Monica

    2013-01-01

    Indirect capping is a complex therapy exclusively needed in deep cavities that provides, using biomaterials, a disinfection of the dentinary sore and seals the dentinary tubules, protects the pulp of physical mechanisms and chemical agents and stimulates the mechanisms that produce new dentin. Following this idea, we studied the histological changes in the dental pulp tissue and also the specific immunohistochemical response in various structures when an indirect capping technique was used. We used special histological techniques followed by classical staining or by immunohistochemical reaction in order to assess the odontoblastic, and the vascular reaction. The immunohistochemical study allows us to evaluate the changes in the pulp-dentin complex, as the result of the changes in the dentinal tubules permeability and the biological reactions at this level.

  17. Reduction in dentin permeability using a slurry containing dicalcium phosphate and calcium hydroxide.

    PubMed

    Cherng, Aishuan Maria; Takagi, Shozo; Chow, Laurence

    2006-08-01

    Treatments that obdurate dentin tubules have been used for reducing dentin hypersensitivity. The purpose of this study was to determine the effect of a treatment with a slurry of micron sized calcium phosphate on the hydraulic conductance (L(p)) of etched dentin discs in vitro. The treatment slurry was prepared by mixing a powder mixture of dicalcium phosphate anhydrous and calcium hydroxide with a solution that contained sodium fluoride and carboxymethyl cellulose. The mean baseline L(p) (in mL cm(-2) s(-1) H(2)O cm(-1)) was 2.07 +/- 1.45 (mean +/- SD; n = 13)). After one treatment and 2, 4, and 7 days of incubation in a protein-free saliva-like solution (SLS), the mean relative L(p), presented as % of baseline, were 65 +/- 16, 42 +/- 27, 36 +/- 26, and 33 +/- 27 (n = 13), respectively. The L(p) values of the baseline and treatment after incubation in the SLS were significantly (p < 0.05) different. Scanning electron microscopic examination showed partial obturation of dentin tubules in the treated dentin. X-ray diffraction and chemical analyses indicated the major product formed from the slurry was a fluoride-containing hydroxyapatite. Treatment appeared effective in further reducing L(p) of dentin discs after incubation in the SLS.

  18. Lipid tubule growth by osmotic pressure

    NASA Astrophysics Data System (ADS)

    Rangamani, Padmini; Zhang, Di; Orster, George; Shen, Amy

    2013-11-01

    We present here a procedure for growing lipid tubules in vitro. This method allows us to grow tubules of consistent shape and structure and thus can be a useful tool for nano-engineering applications. There are three stages during the tubule growth process: initiation, elongation and termination. Balancing the forces that act on the tubule head shows that the growth of tubules during the elongation phase depends on the balance between osmotic pressure and the viscous drag exerted on the membrane from the substrate and the external fluid. Using a combination of mathematical modeling and experiment, we identify the key forces that control tubule growth during the elongation phase.

  19. Characterization of biomodified dentin matrices for potential preventive and reparative therapies

    PubMed Central

    Bedran-Russo, Ana Karina B.; Castellan, Carina. S.; Shinohara, Mirela S.; Hassan, Lina; Antunes, Alberto

    2011-01-01

    Biomodification of existing hard tissue structures, specifically tooth dentin, is an innovative approach proposed to improve the biomechanical and biochemical properties of tissue for potential preventive or reparative/regenerative therapies. The objectives of the study were to systematically characterize dentin matrices biomodified by proanthocyanidin-rich grape seed extract (GSE) and glutaraldehyde (GD). Changes to the biochemistry and biomechanical properties were assessed by several assays to investigate the degree of interactions, biodegradation rates, proteoglycans interaction, and effect of collagen fibril orientation and environmental conditions on the tensile properties. The highest degree of agent-dentin interaction was observed with GSE which exhibited the highest denaturation temperature, regardless of the agent concentration. Biodegradation rates remarkably decreased following biomodification of dentin matrices after 24hs collagenase digestion. A significant decreased in the proteoglycans content of GSE treated samples was observed using a micro-assay for glycosaminoglycans and histological electron microscopy, while no changes were observed for GD and control. Tensile strength properties of GD biomodified dentin matrices were affected by dentin tubule orientation, most likely due to the orientation of the collagen fibrils. Higher and/or increased stability of the tensile properties of GD and GSE-treated samples were observed following exposure to collagenase and 8 month water storage. Biomodification of dentin matrices using chemical agents not only affects the collagen biochemistry; it also involves interaction with proteoglycans. Tissue biomodifiers interact differently with dentin matrices and may provide the tissue with enhanced preventive and restorative/reparative abilities. PMID:21167964

  20. Young's modulus of peritubular and intertubular human dentin by nano-indentation tests.

    PubMed

    Ziskind, Daniel; Hasday, Moran; Cohen, Sidney R; Wagner, H Daniel

    2011-04-01

    The local Young modulus of dry dentin viewed as a hierarchical composite was measured by nano-indentation using two types of experiments, both in a continuous stiffness measurement mode. First, tests were performed radially along straight lines running across highly mineralized peritubular dentin sections and through less mineralized intertubular dentin areas. These tests revealed a gradual decrease in Young's modulus from the bulk of the peritubular dentin region where modulus values of up to ∼40-42GPa were observed, down to approximately constant values of ∼17GPa in the intertubular dentin region. A second set of nano-indentation experiments was performed on the facets of an irregular polyhedron specimen cut from the intertubular dentin region, so as to probe the modulus of intertubular dentin specimens at different orientations relative to the tubular direction. The results demonstrated that the intertubular dentin region may be considered to be quasi-isotropic, with a slightly higher modulus value (∼22GPa) when the indenting tip axis is parallel to the tubular direction, compared to the values (∼18GPa) obtained when the indenting tip axis is perpendicular to the tubule direction.

  1. Inhibition of dentin demineralization by fluoride in vitro.

    PubMed

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

    1998-01-01

    Compared with the knowledge accumulated on enamel-fluoride interactions, relatively little data is available regarding fluoride effects on dentin. This applies to both laboratory and clinical studies into the efficacy of fluoride schemes for the prevention of root surface caries. This study aimed to determine the effects of fluoride and pH on the demineralization of dentin, such as to provide information necessary to develop preventive programmes. Bovine dentin blocks were subjected to undersaturated calcium- and phosphate-containing solutions in the pH range 4.0-6.0 with fluoride added at concentrations between 0.5 and 10 ppm. Non-fluoride solutions served as controls. Mineral loss was assessed chemically and by transversal microradiography. Comparisons were made with similar studies on enamel demineralization. The results showed that demineralization of dentin depends on both pH and fluoride concentration in the demineralizing solution. Inhibition of demineralization that could be relevant from a clinical point of view was found at fluoride values 5-10 times the corresponding values for enamel. Also rapid depletion of fluoride from the solutions was observed, indicating the high uptake capacity of dentin for fluoride. Lesion depth depended on pH of the solution while the fluoride levels were associated with the surface layer, both in mineral content and depth. For dentin we propose a demineralization mechanism where acid penetrates rapidly into the tissue, presumably through the tubules, after which the released calcium and phosphate is partly trapped by the inward diffusing fluoride. This leads to the formation of a surface layer, which may even be hypermineralized compared to sound dentin.

  2. Aging and the reduction in fracture toughness of human dentin.

    PubMed

    Nazari, A; Bajaj, D; Zhang, D; Romberg, E; Arola, D

    2009-10-01

    An evaluation of the crack growth resistance of human coronal dentin was performed on tissue obtained from patients between ages 18 and 83. Stable crack extension was achieved over clinically relevant lengths (0< or = a < or =1mm) under Mode I quasi-static loading and perpendicular to the nominal tubule direction. Results distinguished that human dentin exhibits an increase in crack growth resistance with extension (i.e. rising R-curve) and that there is a significant reduction in both the initiation (K(o)) and plateau (K(p)) components of toughness with patient age. In the young dentin (18< or =age< or =35) there was a 25% increase in the crack growth resistance from the onset of extension (K(o)=1.34 MPa m(0.5)) to the maximum or "plateau" toughness (K(p)=1.65 MPa m(0.5)). In comparison, the crack growth resistance of the old dentin (55< or =age) increased with extension by less than 10% from K(o)=1.08 MPa m(0.5) to K(p)=1.17 MPa m(0.5). In young dentin toughening was achieved by a combination of inelastic deformation of the mineralized collagen matrix and microcracking of the peritubular cuffs. These mechanisms facilitated further toughening via the development of unbroken ligaments of tissue and posterior crack-bridging. Microstructural changes with aging decreased the capacity for near-tip inelastic deformation and microcracking of the tubules, which in turn suppressed the formation of unbroken ligaments and the degree of extrinsic toughening.

  3. AGING AND THE REDUCTION IN FRACTURE TOUGHNESS OF HUMAN DENTIN

    PubMed Central

    Nazari, A.; Bajaj, D.; Zhang, D.; Romberg, E.; Arola, D.

    2009-01-01

    An evaluation of the crack growth resistance of human coronal dentin was performed on tissue obtained from patients between ages 18 and 83. Stable crack extension was achieved over clinically relevant lengths (0 ≤ a ≤1 mm) under Mode I quasi-static loading and perpendicular to the nominal tubule direction. Results distinguished that human dentin exhibits an increase in crack growth resistance with extension (i.e. rising R-curve) and that there is a significant reduction in both the initiation (Ko) and plateau (Kp) components of toughness with patient age. In the young dentin (18≤age≤35) there was a 25 % increase in the crack growth resistance from the onset of extension (Ko =1.34 MPa·m0.5) to the maximum or “plateau” toughness (Kp = 1.65 MPa·m0.5). In comparison, the crack growth resistance of the old dentin (55≤age) increased with extension by less than 10 % from Ko = 1.08 MPa·m0.5 to Kp = 1.17 MPa·m0.5. In young dentin toughening was achieved by a combination of inelastic deformation of the mineralized collagen matrix and microcracking of the peritubular cuffs. These mechanisms facilitated further toughening via the development of unbroken ligaments of tissue and posterior crack-bridging. Microstructural changes with aging decreased the capacity for near-tip inelastic deformation and microcracking of the tubules, which in turn suppressed the formation of unbroken ligaments and the degree of extrinsic toughening. PMID:19627862

  4. Cryopreserved dentin matrix as a scaffold material for dentin-pulp tissue regeneration.

    PubMed

    Jiao, Liang; Xie, Li; Yang, Bo; Yu, Mei; Jiang, Zongting; Feng, Lian; Guo, Weihua; Tian, Weidong

    2014-06-01

    Cryopreservation has been identified as an efficient approach to preserve tissue engineered products for a long term. Our prior studies have suggested that the treated dentin matrix (TDM) could be an ideal bioactive scaffold for dental tissue regeneration. In this study, we hypothesize that the cryopreservation could effectively maintain the survival and viability of dentinogenesis-related proteins of TDM and the cryopreserved dentin matrix (CDM) would provide the suitable biological scaffold and inductive microenvironment for the regeneration of dentin-pulp like tissue. CDM-3 and CDM-6 were prepared by cryopreserving TDM in liquid nitrogen (-196 °C) with cryoprotectant for 3 months and 6 months, respectively. Various biological characteristics of CDM, including mechanical properties, cell proliferation, and odontogenesis ability, were investigated. To further evaluate the inductive capacity of CDM, human dental follicle cells were encapsulated within CDM, and implanted the scaffold into a mouse model for 8 weeks, and the grafts were harvested and assessed histologically. The CDM showed superior mechanical properties than TDM. Compared to TDM, CDM can release more dentinogenesis-related proteins due to the larger pore diameter. Cell proliferation with the addition of CDM extract liquid was similar to that of TDM in the first five days. Human dental follicle cells, under the effect of CDM extract liquid, highly expressed bone sialoprotein, collagen-1, alkaline phosphatase, indicating that CDM, regarded as the inductive microenvironment, plays an important role in odontogenesis. Most importantly, in vivo, CDM could induce dental follicle cells to regenerate new dentin-pulp like tissues, such as dentinal tubules, predentin, collagen fibers, nerves, and blood vessels which were positive for dentin sialophosphoprotein, dental matrix protein-1, Tubulin, and collagen-1. In conclusion, CDM is an ideal biological scaffold material for human dentin-pulp like tissue

  5. Comparative evaluation of self-etching primers with fourth and fifth generation dentin-bonding systems on carious and normal dentin substrates: An in vitro shear bond strength analysis

    PubMed Central

    Giriyappa, Ramesh H; Chandra, B Suresh

    2008-01-01

    Aim: The aim of this study was to test the hypothesis that bonding to caries-affected dentin would yield strengths that are lower than bond strengths achievable when bonded to normal dentin. Dentin-bonding systems used in this study were fourth and fifth generation as well as self-etching primers. Materials and Methods: Forty-eight freshly extracted mandibular and maxillary molars were selected of which 24 were caries-affected teeth and the remaining were noncarious teeth. Random sampling was done with eight teeth in each group based on the bonding system used. In caries-affected teeth, the soft, stainable, caries-infected dentin was excavated using a caries detector dye whereas the hard, caries-affected, nonstainable dentin was retained. All the teeth were subsequently mounted in a suitable acrylic mould. Prepared teeth were restored with a single composite resin, using three different dentin bonding systems. These prepared specimens were transferred to a Hounsfield tensometer to measure the shear bond strength. The results obtained were analyzed using Anova, Student's unpaired t-test, and Student Neuman Keulis test. Results: The results showed that the self-etching primer required the highest mean shear load compared to the fifth and fourth generation dentin-bonding systems in both normal dentin and caries-affected dentin. Conclusion: Bond strength to dentin depends on whether the dentinal tubule is open or occluded. Within the limitations of this study, it was observed that bond strength to caries-affected dentin was low compared to normal dentin. PMID:20351973

  6. CO2 laser improves 45S5 bioglass interaction with dentin.

    PubMed

    Bakry, A S; Takahashi, H; Otsuki, M; Sadr, A; Yamashita, K; Tagami, J

    2011-02-01

    Bioglass 45S5 is a bioactive glass that can create a layer of calcium-phosphate crystals on mineralized hard tissues. In this study, 45S5 bioglass was mixed with phosphoric acid and irradiated with CO(2) laser and examined as a possible aid in the treatment of dentin hypersensitivity. The dentinal surface modified by the aforementioned technique was chemically and micro-morphologically examined with a field emission scanning electron microscope (FE-SEM) equipped with an energy-dispersive x-ray spectroscope (EDS), and the crystalline structures of the examined dentinal surfaces were examined by x-ray diffraction (XRD). Moreover, the mechanical properties of the newly formed layer were examined by nanoindentation. The results showed that 45S5 bioglass could occlude the dentinal tubule orifices with calcium-phosphate crystals. The application of CO(2) laser potentially improved the mechanical organization of these crystals.

  7. Elemental analysis of caries-affected root dentin and artificially demineralized dentin

    PubMed Central

    Sung, Young-Hye; Son, Ho-Hyun; Yi, Keewook

    2016-01-01

    Objectives This study aimed to analyze the mineral composition of naturally- and artificially-produced caries-affected root dentin and to determine the elemental incorporation of resin-modified glass ionomer (RMGI) into the demineralized dentin. Materials and Methods Box-formed cavities were prepared on buccal and lingual root surfaces of sound human premolars (n = 15). One cavity was exposed to a microbial caries model using a strain of Streptococcus mutans. The other cavity was subjected to a chemical model under pH cycling. Premolars and molars with root surface caries were used as a natural caries model (n = 15). Outer caries lesion was removed using a carbide bur and a hand excavator under a dyeing technique and restored with RMGI (FujiII LC, GC Corp.). The weight percentages of calcium (Ca), phosphate (P), and strontium (Sr) and the widths of demineralized dentin were determined by electron probe microanalysis and compared among the groups using ANOVA and Tukey test (p < 0.05). Results There was a pattern of demineralization in all models, as visualized with scanning electron microscopy. Artificial models induced greater losses of Ca and P and larger widths of demineralized dentin than did a natural caries model (p < 0.05). Sr was diffused into the demineralized dentin layer from RMGI. Conclusions Both microbial and chemical caries models produced similar patterns of mineral composition on the caries-affected dentin. However, the artificial lesions had a relatively larger extent of demineralization than did the natural lesions. RMGI was incorporated into the superficial layer of the caries-affected dentin. PMID:27847746

  8. Effect of Citric Acid and Ethylenediaminetetraacetic Acid on the Surface Morphology of Young and Old Root Dentin

    PubMed Central

    Scelza, Miriam Zaccaro; de Noronha, Fernando; da Silva, Licinio Esmeraldo; Maurício, Marcos; Gallito, Marco Antonio; Scelza, Pantaleo

    2016-01-01

    Introduction: The aim of this in vitro study was to evaluate the effect of 10% citric acid and 17% ethylenediaminetetraacetic acid (EDTA) irrigating solutions on the surface morphology of young and old root dentin by determining the number and diameter of dentinal tubules using scanning electron microscopy (SEM). Methods and Materials: Fifty healthy human teeth collected from young (≤30 years) and old (≥60 years) individuals (n=25) were first prepared with a Largo bur #2 to produce smear layer on the root canal surface. Subsequently, the crowns and the root middle and apical thirds were sectioned and removed, and the cervical thirds were sectioned vertically in the buccal-lingual direction into two equal halves. The obtained samples were then immersed in 2.5% sodium hypochlorite for 30 min and randomly separated into two treatment groups for each age group. In each age group, ten samples were selected as controls and did not receive any type of treatment. The rest of the specimens were then rinsed, dried and treated for 4 min with 10% citric acid or 17% EDTA. The samples were then assessed with SEM regarding the number and diameter of dentinal tubules. All data were assessed using Student’s t-test. The level of significance was set at 0.05. Results: Regardless of the type of treatment, no significant differences were observed in the number of open tubules between the young and old root dentin (P>0.05). Nonetheless, the diameter of the tubules in the old root dentin was larger when 17% EDTA was used (P<0.05). Both, young and old root dentin did not differ with the 10% citric acid treatment (P>0.05). Conclusion: The results showed that 17% EDTA treatment induced a significant demineralization in old root dentin. PMID:27471529

  9. Structural analysis of reactionary dentin formed in response to polymicrobial invasion

    PubMed Central

    Charadram, Nattida; Austin, Christine; Trimby, Patrick; Simonian, Mary; Swain, Michael V.; Hunter, Neil

    2013-01-01

    In response to microbial invasion of dentin odontoblasts secrete an altered calcified matrix termed reactionary dentin (Rd). 3D reconstruction of focused-ion-beam scanning electron microscopy (FIB-SEM) image slices revealed helical tubular structures in Rd that contrasted with regular cylindrical tubules characteristic of dentin from healthy teeth and affected so-called physiological dentin (Pd) lying exterior to Rd. This helical structure in Rd provided effective constriction of tubule lumen diameter that formed a barrier to bacterial advance towards the dental pulp. SEM of resin cast preparations revealed altered extension of odontoblast processes through Rd. The distribution of key mineral elements was studied by combination of 3D reconstruction of focused-ion-beam based X-ray microanalysis (FIB-EDS), laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). There was a marked redistribution of calcium and phosphorous in Rd together with an increase of diffusely deposited magnesium compatible with the mineral deposition phase of synthesis of this altered matrix. Changes in tubule structure and mineral content characteristic of Rd are consistent with reduced hardness and lower elastic modulus reported for this matrix. Findings provide insight into the unique structure of Rd synthesised as a primary response to infection. PMID:23261402

  10. Spectroscopic and morphologic characterization of the dentin/adhesive interface

    NASA Astrophysics Data System (ADS)

    Lemor, R. M.; Kruger, Michael B.; Wieliczka, David M.; Swafford, Jim R.; Spencer, Paulette

    1999-01-01

    The potential environmental risks associated with mercury release have forced many European countries to ban the use of dental amalgam. Alternative materials such as composite resins do not provide the clinical function for the length of time characteristically associated with dental amalgam. The weak link in the composite restoration is the dentin/adhesive bond. The purpose of this study was to correlate morphologic characterization of the dentin/adhesive bond with chemical analyses using micro- Fourier transform infrared and micro-Raman spectroscopy. A commercial dental adhesive was placed on dentin substrates cut from extracted, unerupted human third molars. Sections of the dentin/adhesive interface were investigated using infrared radiation produced at the Aladdin synchrotron source; visible radiation from a Kr+ laser was used for the micro-Raman spectroscopy. Sections of the dentin/adhesive interface, differentially stained to identify protein, mineral, and adhesive, were examined using light microscopy. Due to its limited spatial resolution and the unknown sample thickness the infrared results cannot be used quantitatively in determining the extent of diffusion. The results from the micro-Raman spectroscopy and light microscopy indicate exposed protein at the dentin/adhesive interface. Using a laser that reduces background fluorescence, the micro-Raman spectroscopy provides quantitative chemical and morphologic information on the dentin/adhesive interface. The staining procedure is sensitive to sites of pure protein and thus, complements the Raman results.

  11. Bonding of crown and bridge adhesive resins to dentine.

    PubMed

    Osman, Saad A; McCabe, John F; Walls, Angus W G

    2008-12-01

    The shear bond strength of three adhesives, Panavia 21, Superbond, All Bond C&B Cement, and Variolink (a dual cure resin) to various dentine depths were determined. Fifteen human fully erupted permanent first and second molars were wet ground using 500 and then 800 grit abrasive papers to expose the superficial, middle and the deep dentine, for each adhesive tested. Five samples were prepared for each dentine depth. The adhesives were bonded to the samples using gelatine capsules and were matured for 24 h in water at 37 degrees C. The samples were debonded in shear using tensile testing machine at a cross-head speed of 1 mm/min. The data were analysed using ANOVA and the Tukey test. The fracture surfaces were examined by optical microscopy. The bond strength of Superbond to dentine was significantly higher (P<0.05) than any of the materials tested. The bond strength of all materials tested was shown to be affected by dentine depth, except for Superbond. Fractured dentine specimens showed that the samples of Superbond are almost cohesive (>90%), and the samples of other adhesives are mostly adhesive (>70%). These results confirm that Superbond is capable of forming a bond at various dentine depths.

  12. The effect of stromelysin-1 (MMP-3) on non-collagenous extracellular matrix proteins of demineralized dentin and the adhesive properties of restorative resins.

    PubMed

    Boukpessi, T; Menashi, S; Camoin, L; Tencate, J M; Goldberg, M; Chaussain-Miller, C

    2008-11-01

    Dentin non-collagenous matrix components (NCPs) are structural proteins involved in the formation, the architecture and the mineralization of the extracellular matrix (ECM). We investigated here how recombinant metalloproteinase stromelysin-1, also termed MMP-3, initiates the release of ECM molecules from artificially demineralized human dentin. Analysis of the supernatants by Western blotting reveals that MMP-3 extracts PGs (decorin, biglycan), and also a series of phosphorylated proteins: dentin sialoprotein (DSP), osteopontin (OPN), bone sialoprotein (BSP) and MEPE, but neither dentin matrix protein-1 (DMP1), another member of the SIBLING family, nor osteocalcin (OC), a non-phosphorylated matrix molecule. After treatment of dentin surfaces by MMP-3, scanning electron microscope (SEM) examination of resin replica shows an increased penetration of the resin into the dentin tubules when compared to surfaces only treated by demineralizing solutions. This preclinical investigation suggests that MMP-3 may be used to improve the adhesive properties of restorative materials.

  13. Dentin Caries Zones

    PubMed Central

    Pugach, M.K.; Strother, J.; Darling, C.L.; Fried, D.; Gansky, S.A.; Marshall, S.J.; Marshall, G.W.

    2009-01-01

    Caries Detector staining reveals 4 zones in dentin containing caries lesions, but characteristics of each zone are not well-defined. We therefore investigated the physical and microstructural properties of carious dentin in the 4 different zones to determine important differences revealed by Caries Detector staining. Six arrested dentin caries lesions and 2 normal controls were Caries-Detector-stained, each zone (pink, light pink, transparent, apparently normal) being analyzed by atomic force microscopy (AFM) imaging for microstructure, by AFM nano-indentation for mechanical properties, and by transverse digital microradiography (TMR) for mineral content. Microstructure changes, and nanomechanical properties and mineral content significantly decreased across zones. Hydrated elastic modulus and mineral content from normal dentin to pink Caries-Detector-stained dentin ranged from 19.5 [10.6-25.3] GPa to 1.6 [0.0-5.0] GPa and from 42.9 [39.8-44.6] vol% to 12.4 [9.1-14.2] vol%, respectively. Even the most demineralized pink zone contained considerable residual mineral. PMID:19131321

  14. 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

  15. Mineral density, morphology and bond strength of natural versus artificial caries-affected dentin.

    PubMed

    Joves, Gerardo José; Inoue, Go; Nakashima, Syozi; Sadr, Alireza; Nikaido, Toru; Tagami, Junji

    2013-01-01

    This study aimed to investigate an artificial caries-affected dentin (ACAD) model for in vitro bonding studies in comparison to natural caries-affected dentin (NCAD) of human teeth. ACAD was created over 7 days in a demineralizing solution. Mineral density (MD) at different depth levels (0-150 µm) was compared between NCAD and ACAD by transverse microradiography. Micro-tensile bond strengths (µTBS) of two two-step self-etch adhesives to sound dentin, NCAD and ACAD were evaluated. Caries-affected dentin type was not a significant factor when comparing MD at different lesion levels (p>0.05). Under SEM, the dentinal tubules appeared occluded with crystal logs 1-2 µm in thickness in the NCAD; whereas they remained open in the ACAD. The µTBS to caries-affected dentin was lower than sound dentin, but was not affected by the type of caries (p>0.05). In spite of their different morphologies, the ACAD model showed similar MD and µTBS compared to NCAD.

  16. 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

  17. Matrix metalloproteinases and other matrix proteinases in relation to cariology: the era of 'dentin degradomics'.

    PubMed

    Tjäderhane, Leo; Buzalaf, Marília Afonso Rabelo; Carrilho, Marcela; Chaussain, Catherine

    2015-01-01

    Dentin organic matrix, with type I collagen as the main component, is exposed after demineralization in dentinal caries, erosion or acidic conditioning during adhesive composite restorative treatment. This exposed matrix is prone to slow hydrolytic degradation by host collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins. Here we review the recent findings demonstrating that inhibition of salivary or dentin endogenous collagenolytic enzymes may provide preventive means against progression of caries or erosion, just as they have been shown to retain the integrity and improve the longevity of resin composite filling bonding to dentin. This paper also presents the case that the organic matrix in caries-affected dentin may not be preserved as intact as previously considered. In partially demineralized dentin, MMPs and cysteine cathepsins with the ability to cleave off the terminal non-helical ends of collagen molecules (telopeptides) may lead to the gradual loss of intramolecular gap areas. This would seriously compromise the matrix ability for intrafibrillar remineralization, which is considered essential in restoring the dentin's mechanical properties. More detailed data of the enzymes responsible and their detailed function in dentin-destructive conditions may not only help to find new and better preventive means, but better preservation of demineralized dentin collagenous matrix may also facilitate true biological remineralization for the better restoration of tooth structural and mechanical integrity and mechanical properties.

  18. Immediate and delayed micro-tensile bond strength of different luting resin cements to different regional dentin.

    PubMed

    Ali, Abdelraheem Mohamed; Hamouda, Ibrahim Mohamed; Ghazy, Mohamed Hamed; Abo-Madina, Manal Mohamed

    2013-03-01

    We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multilink Sprint resin cement to superficial, deep and cervical dentin. Thirty-six freshly extracted non-carious human molars were sectioned in the mesiodistal direction to expose three different dentin regions including superficial dentin (1 mm below the dentine-enamel junction), deep dentin (1 mm above the highest pulp horn) and cervical dentin (0.5 mm above the cemento-enamel junction and 0.5 mm below the dentine-enamel junction). Resin cements were applied on dentin surfaces and composite blocks were luted under constant seating pressure. Each group was divided into three subgroups according to time intervals. Specimens were sectioned to obtain sticks of 1 mm(2) in diameter and subjected to microtensile bond strength testing at a cross head speed of 1 mm/min. Both resin cements showed higher micro-tensile bond strength to superficial dentin than that to deep or cervical dentin (P < 0.001). Micro-tensile bond strengths of Panavia F2.0 were higher than those of Multilink Sprint at different dentin regions (P < 0.001). Immediate micro-tensile bond strengths were higher than those of delayed micro-tensile bond strengths for both resin cements (P < 0.001). It was concluded that resin cements with different chemical formulations and applications yield significantly different micro-tensile bond strengths to different dentin regions.

  19. The effect of 30% ethanolic extract of Indian propolis on replica of human dentin compared against commercially available desensitizing agent: A methodological SEM study in vitro

    PubMed Central

    Hongal, Sudhir; Torwane, Nilesh Arjun; Goel, Pankaj; Chandrashekar, Byarakele

    2014-01-01

    Objective: This study evaluated the ability of 30% ethanolic extract of Indian propolis on dentinal tubule occlusion comparatively against CPP-ACP containing desensitizing agent GC tooth mousse. Methodology: The specimens were prepared from 30 freshly extracted sound human third molars stored in 10% formalin (pH 7.0) at a room temperature. From each specimen, a sectioned sample (5 mm length × 5 mm width × 3.5 mm depth) was obtained including the cervical area. Samples were smoothened and wet-polished with 1000- and 1200-grit aluminum oxide abrasive paper and diamond pastes, in order to stimulate the clinical aspect of hypersensitive dentin cervical surfaces. All the specimens were randomly assigned to three groups (n = 10), according to dentin surface treatments. Negative control: Untreated specimens (n = 4) and pretreated with 6% citric acid (n = 6); Test Group: 30% ethanolic extract of Indian propolis (n = 10); Positive Group: GC Tooth Mousse (n =10). All the specimens were prepared for SEM analysis. Results: GC tooth mousse promoted tubule occlusion by crystal-like deposits in the lumen of the tubules. While propolis created a thin, smooth layer over dentin surface. Conclusion: According to the SEM analysis, both desensitizing agent were able to occlude the dentinal tubules. PMID:24761114

  20. Influence of immediate dentin sealing on the shear bond strength of pressed ceramic luted to dentin with self-etch resin cement.

    PubMed

    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.

  1. Isolation of surface tubules of fowlpox virus.

    PubMed

    Carter, J K; Cheville, N F

    1981-01-01

    Surface tubules of fowlpox virus were isolated using chemical and physical methods. Suspensions of lipid cytoplasmic inclusion bodies were obtained by treating infected chorioallantoic membranes with 1% trypsin. Inclusions were treated with ultrasonic sound, detergents, and enzymes and were examined by electron microscopy. Although lipase treatment altered the morphology of lipid inclusions, no viral surface tubules were recovered. Treatment with the detergent Nonidet-P40 followed by 2-mercaptoethanol disrupted virions without allowing surface tubules to be recovered. Disruption of lipid inclusions by ultrasonic sound or manual grinding of chorioallantoic membranes produced free virions but only small numbers of tubules. These results indicate that surface tubules can be recovered, but that the lipid nature of cytoplasmic inclusions interferes with procedures commonly used in tubule purification.

  2. Primer containing dimethylaminododecyl methacrylate kills bacteria impregnated in human dentin blocks

    PubMed Central

    Chen, Chen; Cheng, Lei; Weir, Michael D; Lin, Nancy J; Lin-Gibson, Sheng; Zhou, Xue-Dong; Xu, Hockin HK

    2016-01-01

    Antibacterial dimethylaminododecyl methacrylate (DMADDM) was recently synthesized. The objectives of this study were to: (1) investigate antibacterial activity of DMADDM-containing primer on Streptococcus mutans impregnated into dentin blocks for the first time, and (2) compare the antibacterial efficacy of DMADDM with a previous quaternary ammonium dimethacrylate (QADM). Scotchbond Multi-Purpose (SBMP) bonding agent was used. DMADDM and QADM were mixed into SBMP primer. Six primers were tested: SBMP control primer P, P+2.5% DMADDM, P+5% DMADDM, P+7.5% DMADDM, P+10% DMADDM, and P+10% QADM. S. mutans were impregnated into human dentin blocks, and each primer was applied to dentin to test its ability to kill bacteria in dentinal tubules. Bacteria in dentin were collected via a sonication method, and the colony-forming units (CFU) and inhibition zones were measured. The bacterial inhibition zone of P+10% DMADDM was 10 times that of control primer (P<0.05). CFU in dentin with P+10% DMADDM was reduced by three orders of magnitude, compared with control. DMADDM had a much stronger antibacterial effect than QADM, and antibacterial efficacy increased with increasing DMADDM concentration. Dentin shear bond strengths were similar among all groups (P>0.1). In conclusion, antibacterial DMADDM-containing primer was validated to kill bacteria inside dentin blocks, possessing a much stronger antibacterial potency than the previous QADM. DMADDM-containing bonding agent was effective in eradicating bacteria in dentin, and its efficacy was directly proportional to DMADDM mass fraction. Therefore, DMADDM may be promising for use in bonding agents as well as in other restorative and preventive materials to inhibit bacteria. PMID:27811846

  3. Microstructure and wettability of root canal dentine and root canal filling materials after different chemical irrigation

    NASA Astrophysics Data System (ADS)

    Antonijevic, Djordje; Milovanovic, Petar; Brajkovic, Denis; Ilic, Dragan; Hahn, Michael; Amling, Michael; Rakocevic, Zlatko; Djuric, Marija; Busse, Björn

    2015-11-01

    The objective of this study was to determine the effects of various irrigation solutions on root canal dentine and gutta-percha surface properties. In addition, the effects of disinfectant chemicals on the wettability and surface morphological properties of the filling materials were evaluated. Ethylenediaminetetraacetic acid (EDTA), citric acid, and ozone were employed as irrigation solutions for dentine and gutta-percha treatment. Thereafter, the samples' microstructure, degree of mineralization, and mechanical properties were assessed by means of quantitative backscattered electron imaging (qBEI) and reference point indentation (RPI). A contact angle analyzer was used to measure adhesion on the tested materials. Here, EDTA had the most significant affect on both the mechanical properties and the adhesive behavior of dentine. Citric acid did not affect dentine wettability, whereas the indentation properties and the mineralization were reduced. Similar effects were observed when ozone was used. The dentinal tubules were significantly widened in citric acid compared to the ozone group. EDTA causes considerable micromechanical surface alteration of dentine and gutta-percha, but represents the best option in clinical cases where a high adhesiveness of the filling materials is desired.

  4. In vitro efficacy of a novel potassium oxalate hydrogel for dentin hypersensitivity.

    PubMed

    Varoni, Elena M; Zuccheri, Tommaso; Carletta, Andrea; Palazzo, Barbara; Cochis, Andrea; Colonna, Martino; Rimondini, Lia

    2017-04-01

    A novel potassium oxalate-based hydrogel is proposed for treating dentin hypersensitivity and this study evaluates its in vitro performance as a remineralizing, desensitizing agent. Etched disks of human dentin were treated for 10 or 20 min using the test hydrogel, to mimic a professional application with dental mouth guards. Dentin disks were evaluated in terms of permeability indexes in a fluid-filled system, the surface morphology was assessed by scanning electron microscopy, and the structural properties were studied using X-ray diffraction analysis. The potassium oxalate hydrogel significantly reduced dentin permeability, in a time-dependent manner, and occluded most of the patent dentinal tubules via crystal precipitation, forming a remineralized layer. After hydrogel treatments, an acid solution (pH 4.2) was applied to the disks for 30 s, or 1, 2, or 5 min, in order to reproduce a plaque-like oral acidity, and further analysis showed a good resistance of the remineralized layer to the acid challenge. The potassium oxalate-based hydrogel showed a better performance over commercially available products and artificial saliva, appearing a promising candidate for the treatment of dentin hypersensitivity.

  5. 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

  6. BOND STRENGTH OF RESIN MODIFIED GLASS IONOMER CEMENT TO PRIMARY DENTIN AFTER CUTTING WITH DIFFERENT BUR TYPES AND DENTIN CONDITIONING

    PubMed Central

    Nicoló, Rebeca Di; Shintome, Luciana Keiko; Myaki, Silvio Issáo; Nagayassu, Marcos Paulo

    2007-01-01

    The aim of this in vitro study was to evaluate the effect of different bur types and acid etching protocols on the shear bond strength (SBS) of a resin modified glass ionomer cement (RM-GIC) to primary dentin. Forty-eight clinically sound human primary molars were selected and randomly assigned to four groups (n=12). In G1, the lingual surface of the teeth was cut with a carbide bur until a 2.0-mm-diameter dentin area was exposed, followed by the application of RM-GIC (Vitremer – 3M/ESPE) prepared according to the manufacturer’s instructions. The specimens of G2, received the same treatment of G1, however the dentin was conditioned with phosphoric acid. In groups G3 and G4 the same procedures of G1 and G2 were conducted respectively, nevertheless dentin cutting was made with a diamond bur. The specimens were stored in distilled water at 37°C for 24h, and then tested in a universal testing machine. SBS. data were submitted to 2-way ANOVA (= 5%) and indicated that SBS values of RM-GIC bonded to primary dentin cut with different burs were not statistically different, but the specimens that were conditioned with phosphoric acid presented SBS values significantly higher that those without conditioning. To observe micromorphologic characteristics of the effects of dentin surface cut by diamond or carbide rotary instruments and conditioners treatment, some specimens were examined by scanning electron microscopy. Smear layer was present in all specimens regardless of the type of rotary instrument used for dentin cutting, and specimens etched with phosphoric acid presented more effective removal of smear layer. It was concluded that SBS of a RM-GIC to primary dentin was affected by the acid conditioning but the bur type had no influence. PMID:19089179

  7. Effects of dentin depth and cavity configuration on bond strength.

    PubMed

    Yoshikawa, T; Sano, H; Burrow, M F; Tagami, J; Pashley, D H

    1999-04-01

    During polymerization of resin composites, shrinkage stresses compete with resin-dentin bonds in a manner that can cause failure of the bond, depending upon the configuration of the cavity, its depth, and the restorative technique. The hypothesis tested in this study was that the effect of cavity configuration (C) and remaining dentin thickness (RDT) influence resin bond strength to the dentin of Class I cavity floors. The occlusal enamel was ground to expose a flat superficial dentin surface as a control (superficial dentin, C-factor = 1) in human extracted third molars. Cavities 3 mm long x 4 mm wide were prepared to a depth 2 mm below the ground dentin surfaces (deep dentin within cavity floor, C-factor = 3). To assess the relationship between C-factor and RDT, we removed the walls of cavities, making a deep flat surface for bonding (deep dentin, C-factor = 1). The teeth were restored with either Clearfil Liner Bond II (LB II), One-Step (OS), or Super-Bond D Liner (DL), followed by Clearfil Photo Posterior resin composite. After 24 hrs' storage in water, the teeth were sectioned vertically into 3 or 4 slabs (0.7 mm thick) and trimmed for the micro-tensile bond test so that we could determine the strength of the resin bonds to the pulpal floor. All groups gave high bond strengths to superficial dentin, but OS and DL gave significantly lower bond strengths to flat deep dentin when the C-factor was 1. When the C-factor was increased to 3 by the creation of a three-dimensional cavity preparation, the bond strengths of all materials fell (range, 21 to 35%), but the difference was significant (p < 0.05) only with DL. SEM observations of failure patterns showed that specimens with high bond strengths tended to exhibit cohesive failures within the hybrid layer, while specimens exhibiting low bond strengths showed failures at the top of the hybrid layer. Some adhesives do not bond well to deep dentin, making them more susceptible to polymerization shrinkage stress that

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

    PubMed

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

    2011-02-01

    Dentin matrix metalloproteinases (MMPs) are involved in the degradation of collagen in resin-dentin interfaces. This study evaluated whether collagen degradation can be prevented by chlorhexidine digluconate (CHX) after different dentin demineralization procedures. The demineralization of human dentin was performed with phosphoric acid (PA), EDTA or acidic monomers (Clearfil SE Bond and Xeno V). Specimens were stored (for 24 h, or for 1 or 3 wk) in the presence or absence of CHX. In half of the groups, active MMP-2 was incorporated into the storage solution. At the end of each storage period, the C-terminal telopeptide (ICTP) concentration (which indicates the amount of collagen degradation) was measured in the storage solution. Collagen degradation was higher in PA- and EDTA-demineralized dentin. Chlorhexidine digluconate reduced collagen degradation in these groups only for 24 h. When dentin was demineralized with Clearfil SE Bond or Xeno V, collagen degradation was reduced by up to 30%, but the addition of exogenous MMP-2 significantly increased collagen degradation. In self-etchant-treated dentin, the inhibitory effect of CHX on MMPs lasted for up to 3 wk. Treating dentin with EDTA, PA or self-etching agents produces enough demineralization to permit cleavage of the exposed collagen. Monomer 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 with the short-acting PA- or EDTA-treated dentin.

  9. 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

  10. Inhibition of matrix metalloproteinase activity in human dentin via novel antibacterial monomer

    PubMed Central

    Li, Fang; Majd, Hessam; Weir, Michael D.; Arola, Dwayne D.; Xu, Hockin H.K.

    2015-01-01

    Objectives Dentin-composite bond failure is caused by factors including hybrid layer degradation, which in turn can be caused by hydrolysis and enzymatic degradation of the exposed collagen in the dentin. The objectives of this study were to investigate a new antibacterial monomer (dimethylaminododecyl methacrylate, DMADDM) as an inhibitor for matrix metalloproteinases (MMPs), and to determine the effects of DMADDM on both soluble recombinant human MMPs (rhMMPs) and dentin matrix-bound endogenous MMPs. Methods Inhibitory effects of DMADDM at six mass% (0.1% to 10%) on soluble rhMMP-8 and rhMMP-9 were measured using a colorimetic assay. Matrix-bound endogenous MMP activity was evaluated in demineralized human dentin. Dentin beams were divided into four groups (n = 10) and incubated in calcium- and zinc-containing media (control medium); or control medium + 0.2% chlorhexidine (CHX); 5% 12-methacryloyloxydodecylpyridinium bromide (MDPB); or 5% DMADDM. Dissolution of dentin collagen peptides was evaluated by mechanical testing in three-point flexure, loss of dentin mass, and a hydroxyproline assay. Results Use of 0.1% to 10% DMADDM exhibited a strong concentration-dependent anti-MMP effect, reaching 90% of inhibition on rhMMP-8 and rhMMP-9 at 5% DMADDM concentration. Dentin beams in medium with 5% DMADDM showed 34% decrease in elastic modulus (vs. 73% decrease for control), 3% loss of dry dentin mass (vs. 28% loss for control), and significantly less solubilized hydroxyproline when compared with control (p < 0.05). Significance The new antibacterial monomer DMADDM was effective in inhibiting both soluble rhMMPs and matrix-bound human dentin MMPs. These results, together with previous studies showing that adhesives containing DMADDM inhibited biofilms without compromising dentin bond strength, suggest that DMADDM is promising for use in adhesives to prevent collagen degradation in hybrid layer and protect the resin-dentin bond. PMID:25595564

  11. Morphological evaluation of rat incisor enamel and dentin induced by pregnancy and lactation using a scanning electron microscope.

    PubMed

    Ozbek, Murat; Dural, Sema; Kanli, Aydan; Tuncel, Murvet; Orhan, Kaan

    2009-10-01

    This study assessed the effects of pregnancy and lactation on the morphology of the dentine tubules and external enamel surface of rat incisor teeth using a scanning electron microscope (SEM) equipped with an energy dispersive x-ray (EDX) system. Twenty-four female Wistar rats were divided into three groups; group A rats were at the end of pregnancy, group B rats were in the post-lactation period and group C rats, the control group, were unmated. The outer enamel surface and openings of the dentine tubules at the neck regions of the incisors were observed under the SEM and photographed. Examination of the incisor teeth of pregnant and post-lactation rats revealed scratches on the enamel surface. There were few eroded areas and slight changes and the dentine tubules of the pregnant group were fully or partially occluded on the entire surface of the enamel in the lactating rats. Almost all dentine tubules of the rats in this group were open. During the study, EDX analysis of calcium, phosphate and magnesium was also performed at 20 kV and 0 degree tilt. The results of EDX analyses of magnesium were significantly lower in the pregnant group compared with the lactation and control groups for the dentine in the neck region (p<0.05). The calcium values increased in the lactation group compared with those of the rats in the other two groups (p<0.05). These results might indicate that changes during pregnancy and lactation affect the content and morphology of mineralized dental hard tissue.

  12. Adhesion of different resin cements to enamel and dentin.

    PubMed

    Naumova, Ella A; Ernst, Saskia; Schaper, Katharina; Arnold, Wolfgang H; Piwowarczyk, Andree

    2016-01-01

    The purpose of this in vitro study was to compare the shear bond strength (SBS) of five different resin cements to human enamel and dentin under different storage conditions. Five resin cements and their dedicated systems were tested. Teeth were embedded, ground flat to expose enamel or dentin and polished with sandpaper. Adhesive systems were applied according to the manufacturers'instructions. V2A steel cylinders with were silicated, coated, and cemented onto the teeth. Specimens were stored at three different conditions and subsequently thermocycled. SBS was measured. Significant differences were observed between the tested resin cements depending on the tooth surface. Different storage conditions influenced the bond strength, independent of the tooth surface, in all test cements. The bond strength of all experimental materials to enamel is higher than that to dentin surfaces. Furthermore, the adhesiveness decreases after wetness (hydro-) and hydrothermal stress, regardless of the tooth surface.

  13. X-ray microanalysis of dentin: a review

    SciTech Connect

    Hals, E.; Tveit, A.B.; Totdal, B.

    1988-03-01

    The aim of this review was to present a condensed summary of the literature on X-ray microanalysis of dentin, including both energy-dispersive (EDS) and wavelength-dispersive (WDS) analysis. Estimations of concentrations by XMA of dentin should be regarded as semiquantitative values. The Ca level in rat odontoblasts was elevated in the secreting end of the cell body. In predentin Ca accumulated at a concentration of 2% that of mineralized dentin. In coronal dentin the peritubular areas were hypermineralized (Ca, P, Mg). Primary caries lesions showed a decrease of Ca, P, Mg and Cl, and usually an increase of S and Zn. The mineralized surface often present contained especially high concentrations of F and K. Considerable uptake of various ions in cavity walls exposed to filling materials was assessed: from silver amalgam, Zn and Sn, from silicate cement and glassionomer cement F, Al and Zn, and from zinc oxide-eugenol cement, Zn. The highest F concentrations following topical application were found with solutions of TiF4 and with the varnishes Duraphat and Fluor Protector. Dentin wall lesions adjacent to amalgam fillings exhibited considerably reduced Ca and P values, but concomitantly considerable amounts of Zn and Sn, that explained the increased radiopacity seen in some microradiographs. 84 references.

  14. Insights into the structure and composition of the peritubular dentin organic matrix and the lamina limitans.

    PubMed

    Bertassoni, Luiz Eduardo; Stankoska, Katerina; Swain, Michael Vincent

    2012-02-01

    Dentin is a mineralized dental tissue underlying the outer enamel that has a peculiar micro morphology. It is composed of micrometer sized tubules that are surrounded by a highly mineralized structure, called peritubular dentin (PTD), and embedded in a collagen-rich matrix, named intertubular dentin. The PTD has been thought to be composed of a highly mineralized collagen-free organic matrix with unknown composition. Here we tested the hypothesis that proteoglycans and glycosaminoglycans, two important organic structural features found in dentin, are key participants in the microstructure and composition of the PTD. To test this hypothesis dentin blocks were demineralized with 10 vol% citric acid for 2 min and either digested with 1mg/ml TPCK-treated trypsin with 0.2 ammonium bicarbonate at pH 7.9 (TRY) or 0.1 U/mL C-ABC with 50mM Tris, 60mM sodium acetate and 0.02% bovine serum albumin at pH 8.0 (C-ABC). TRY is known to cleave the protein core of dentin proteoglycans, whereas C-ABC is expected to selectively remove glycosaminoglycans. All specimens were digested for 48 h in 37°C, dehydrated in ascending grades of acetone, immersed in HMDS, platinum coated and imaged using an FE-SEM. Images of demineralized dentin revealed a meshwork of noncollagenous fibrils protruding towards the tubule lumen following removal of the peritubular mineral and confirmed the lack of collagen in the peritubular matrix. Further, images revealed that the peritubular organic network originates from a sheet-like membrane covering the entire visible length of tubule, called lamina limitans. Confirming our initial hypothesis, after the digestion with C-ABC the organic network appeared to vanish, while the lamina limitans was preserved. This suggests that glycosaminoglycans are the main component of the PTD organic network. Following digestion with TRY, both the organic network and the lamina limitans disappeared, thus suggesting that the lamina limitans may be primarily composed of

  15. Dentin Sialophosphoprotein (DSPP) in Biomineralization

    PubMed Central

    Prasad, Monica; Butler, William T.; Qin, Chunlin

    2010-01-01

    Two of the proteins found in significant quantity in the extracellular matrix (ECM) of dentin are dentin phosphoprotein (DPP) and dentin sialoprotein (DSP). DPP, the most abundant of the non-collagenous proteins in dentin is an unusually polyanionic protein, containing a large number of aspartic acids (Asp) and phosphoserines (Pse) in the repeating sequences of (Asp-Pse)n. and (Asp-Pse-Pse)n. The many negatively charged regions of DPP are thought to promote mineralization by binding calcium and presenting it to collagen fibers at the mineralization front during the formation of dentin. This purported role of DPP is supported by a sizeable pool of in vitro mineralization data showing that DPP is an important initiator and modulator for the formation and growth of hydroxyapatite crystals. Quite differently, DSP is a glycoprotein, with little or no phosphate. DPP and DSP are the cleavage products of dentin sialophosphoprotein (DSPP). Human and mouse genetic studies have demonstrated that mutations in, or knockout of, the Dspp gene result in mineralization defects in dentin and/or bone. The discoveries in the past 40 years with regard to DPP, DSP and DSPP have greatly enhanced our understanding of biomineralization and set a new stage for future studies. In this review, we summarize the important and new developments made in the past four decades regarding the structure and regulation of the DSPP gene, the biochemical characteristics of DSPP, DPP and DSP, as well as the cell/tissue localizations and functions of these molecules. PMID:20367116

  16. On the fracture of human dentin: Is it stress- orstrain-controlled?

    SciTech Connect

    Nalla, R.K.; Kinney, J.H.; Ritchie, R.O.

    2006-02-01

    Despite substantial clinical interest in the fractureresistance of human dentin, there is little mechanistic information inarchival literature that can be usefully used to model such fracture. Infact, although the fracture event indent in, akin to other mineralizedtissues like bone, is widely believed to be locally strain-controlled,there has never been any scientific proof to support this belief. Thepresent study seeks to address this issue through the use of a novel setof in vitro experiments in Hanks' balanced salt solution involving adouble-notched bend test geometry, which is designed to discern whetherthe critical failure events involved in the onset of fracture are locallystress- or strain-controlled. Such experiments are further used tocharacterize the notion of "plasticity" in dentin and the interaction ofcracks with the salient microstructural features. It is observed thatfracture in dentin is indeed locally strain-controlled and that thepresence of dentinal tubules does not substantially affect this processof crack initiation and growth. The results presented are believed to becritical steps in the development ofa micromechanical model for thefracture of human dentin that takes into consideration the influence ofboth the microstructure and the local failure mode.

  17. On the fracture of human dentin: Is it stress- orstrain-controlled?

    SciTech Connect

    Nalla, R.K.; Kinney, J.H.; Ritchie, R.O.

    2006-02-01

    Despite substantial clinical interest in the fracture resistance of human dentin, there is little mechanistic information in archival literature that can be usefully used to model such fracture. In fact, although the fracture event indent in, akin to other mineralized tissues like bone, is widely believed to be locally strain-controlled, there has never been any scientific proof to support this belief. The present study seeks to address this issue through the use of a novel set of in vitro experiments in Hanks' balanced salt solution involving a double-notched bend test geometry, which is designed to discern whether the critical failure events involved in the onset of fracture are locally stress- or strain-controlled. Such experiments are further used to characterize the notion of ''plasticity'' in dentin and the interaction of cracks with the salient microstructural features. It is observed that fracture in dentin is indeed locally strain-controlled and that the presence of dentinal tubules does not substantially affect this process of crack initiation and growth. The results presented are believed to be critical steps in the development of a micromechanical model for the fracture of human dentin that takes into consideration the influence of both the microstructure and the local failure mode.

  18. Collagen Orientation and Crystallite Size in Human Dentin: A Small Angle X-ray Scattering Study

    SciTech Connect

    Pople, John A.

    2001-03-29

    The mechanical properties of dentin are largely determined by the intertubular dentin matrix, which is a complex composite of type I collagen fibers and a carbonate-rich apatite mineral phase. The authors perform a small angle x-ray scattering (SAXS) study on fully mineralized human dentin to quantify this fiber/mineral composite architecture from the nanoscopic through continuum length scales. The SAXS results were consistent with nucleation and growth of the apatite phase within periodic gaps in the collagen fibers. These mineralized fibers were perpendicular to the dentinal tubules and parallel with the mineralization growth front. Within the plane of the mineralization front, the mineralized collagen fibers were isotropic near the pulp, but became mildly anisotropic in the mid-dentin. Analysis of the data also indicated that near the pulp the mineral crystallites were approximately needle-like, and progressed to a more plate-like shape near the dentino-enamel junction. The thickness of these crystallites, {approx} 5 nm, did not vary significantly with position in the tooth. These results were considered within the context of dentinogenesis and maturation.

  19. Calcium Oxalate Accumulation in Malpighian Tubules of Silkworm (Bombyx mori)

    NASA Astrophysics Data System (ADS)

    Wyman, Aaron J.; Webb, Mary Alice

    2007-04-01

    Silkworm provides an ideal model system for study of calcium oxalate crystallization in kidney-like organs, called Malpighian tubules. During their growth and development, silkworm larvae accumulate massive amounts of calcium oxalate crystals in their Malpighian tubules with no apparent harm to the organism. This manuscript reports studies of crystal structure in the tubules along with analyses identifying molecular constituents of tubule exudate.

  20. Polymer Nanocarriers for Dentin Adhesion

    PubMed Central

    Osorio, R.; Osorio, E.; Medina-Castillo, A.L.; Toledano, M.

    2014-01-01

    To obtain more durable adhesion to dentin, and to protect collagen fibrils of the dentin matrix from degradation, calcium- and phosphate-releasing particles have been incorporated into the dental adhesive procedure. The aim of the present study was to incorporate zinc-loaded polymeric nanocarriers into a dental adhesive system to facilitate inhibition of matrix metalloproteinases (MMPs)-mediated collagen degradation and to provide calcium ions for mineral deposition within the resin-dentin bonded interface. PolymP-nActive nanoparticles (nanoMyP) were zinc-loaded through 30-minute ZnCl2 immersion and tested for bioactivity by means of 7 days’ immersion in simulated body fluid solution (the Kokubo test). Zinc-loading and calcium phosphate depositions were examined by scanning and transmission electron microscopy, elemental analysis, and x-ray diffraction. Nanoparticles in ethanol solution infiltrated into phosphoric-acid-etched human dentin and Single Bond (3M/ESPE) were applied to determine whether the nanoparticles interfered with bonding. Debonded sticks were analyzed by scanning electron microscopy. A metalloproteinase collagen degradation assay was also performed in resin-infiltrated dentin with and without nanoparticles, measuring C-terminal telopeptide of type I collagen (ICTP) concentration in supernatants, after 4 wk of immersion in artificial saliva. Numerical data were analyzed by analysis of variance (ANOVA) and Student-Newman-Keuls multiple comparisons tests (p < .05). Nanoparticles were effectively zinc-loaded and were shown to have a chelating effect, retaining calcium regardless of zinc incorporation. Nanoparticles failed to infiltrate demineralized intertubular dentin and remained on top of the hybrid layer, without altering bond strength. Calcium and phosphorus were found covering nanoparticles at the hybrid layer, after 24 h. Nanoparticle application in etched dentin also reduced MMP-mediated collagen degradation. Tested nanoparticles may be

  1. Polymer nanocarriers for dentin adhesion.

    PubMed

    Osorio, R; Osorio, E; Medina-Castillo, A L; Toledano, M

    2014-12-01

    To obtain more durable adhesion to dentin, and to protect collagen fibrils of the dentin matrix from degradation, calcium- and phosphate-releasing particles have been incorporated into the dental adhesive procedure. The aim of the present study was to incorporate zinc-loaded polymeric nanocarriers into a dental adhesive system to facilitate inhibition of matrix metalloproteinases (MMPs)-mediated collagen degradation and to provide calcium ions for mineral deposition within the resin-dentin bonded interface. PolymP- N : Active nanoparticles (nanoMyP) were zinc-loaded through 30-minute ZnCl2 immersion and tested for bioactivity by means of 7 days' immersion in simulated body fluid solution (the Kokubo test). Zinc-loading and calcium phosphate depositions were examined by scanning and transmission electron microscopy, elemental analysis, and x-ray diffraction. Nanoparticles in ethanol solution infiltrated into phosphoric-acid-etched human dentin and Single Bond (3M/ESPE) were applied to determine whether the nanoparticles interfered with bonding. Debonded sticks were analyzed by scanning electron microscopy. A metalloproteinase collagen degradation assay was also performed in resin-infiltrated dentin with and without nanoparticles, measuring C-terminal telopeptide of type I collagen (ICTP) concentration in supernatants, after 4 wk of immersion in artificial saliva. Numerical data were analyzed by analysis of variance (ANOVA) and Student-Newman-Keuls multiple comparisons tests (p < .05). Nanoparticles were effectively zinc-loaded and were shown to have a chelating effect, retaining calcium regardless of zinc incorporation. Nanoparticles failed to infiltrate demineralized intertubular dentin and remained on top of the hybrid layer, without altering bond strength. Calcium and phosphorus were found covering nanoparticles at the hybrid layer, after 24 h. Nanoparticle application in etched dentin also reduced MMP-mediated collagen degradation. Tested nanoparticles may be

  2. Enamel and dentine demineralization by a combination of starch and sucrose in a biofilm - caries model.

    PubMed

    Botelho, Juliana Nunes; Villegas-Salinas, Mario; Troncoso-Gajardo, Pía; Giacaman, Rodrigo Andrés; Cury, Jaime Aparecido

    2016-05-20

    Sucrose is the most cariogenic dietary carbohydrate and starch is considered non-cariogenic for enamel and moderately cariogenic for dentine. However, the cariogenicity of the combination of starch and sucrose remains unclear. The aim of this study was to evaluate the effect of this combination on Streptococcus mutans biofilm composition and enamel and dentine demineralization. Biofilms of S. mutans UA159 were grown on saliva-coated enamel and dentine slabs in culture medium containing 10% saliva. They were exposed (8 times/day) to one of the following treatments: 0.9% NaCl (negative control), 1% starch, 10% sucrose, or 1% starch and 10% sucrose (starch + sucrose). To simulate the effect of human salivary amylase on the starch metabolization, the biofilms were pretreated with saliva before each treatment and saliva was also added to the culture medium. Acidogenicity of the biofilm was estimated by evaluating (2 times/day) the culture medium pH. After 4 (dentine) or 5 (enamel) days of growth, biofilms (n = 9) were individually collected, and the biomass, viable microorganism count, and polysaccharide content were quantified. Dentine and enamel demineralization was assessed by determining the percentage of surface hardness loss. Biofilms exposed to starch + sucrose were more acidogenic and caused higher demineralization (p < 0.0001) on either enamel or dentine than those exposed to each carbohydrate alone. The findings suggest that starch increases the cariogenic potential of sucrose.

  3. Anacardic acid from brazilian cashew nut trees reduces dentine erosion.

    PubMed

    Silveira, Cintia; Oliveira, Flávia; Dos Santos, Maria Lucilia; de Freitas, Thiago; Imparato, José Carlos; Magalhães, Ana Carolina

    2014-01-01

    The aim of this study was to analyze the effect of solutions containing saturated anacardic acid (AA) on dentine erosion in vitro. AA was chemically isolated from natural cashew nutshell liquid obtained by continuous extraction in a Soxhlet extractor and was fully saturated by catalytic hydrogenation. Matrix metalloproteinase 2 (MMP-2) activity, when exposed to buffers containing 100 µmol/l AA, was analyzed using zymography. Bovine root samples were subjected to erosive demineralization (Sprite Zero™, 4 × 90 s/day) and remineralization with artificial saliva between the erosive cycles for 5 days. The samples were treated as follows, after the first and the last acid exposure (1 min; n = 12/group): (1) 100 µmol/l epigallocatechin-3-gallate (EGCG) (positive control); (2) 0.05% NaF; (3) 100 µmol/l saturated AA; (4) saturated AA and EGCG; (5) saturated AA, EGCG and NaF; (6) untreated (negative control). Dentine erosion was measured using a contact profilometer. Two dentine samples from each group were analyzed using scanning electron microscopy. Saturated AA reduced the activity of MMP-2. ANOVA and Tukey's test revealed that all treatments significantly reduced dentine loss compared to the negative control (6.03 ± 0.98 µm). Solutions containing saturated AA (1.97 ± 1.02 µm) showed the greatest reduction in dentine erosion compared to the NaF (3.93 ± 1.54 µm) and EGCG (3.79 ± 0.83 µm) solutions. Therefore, it may be concluded that AA significantly reduces dentine erosion in vitro, possibly by acting as an MMP-2 inhibitor.

  4. An In Vitro Comparison of the Bond Strength of Composite to Superficial and Deep Dentin, Treated With Er:YAG Laser Irradiation or Acid-Etching.

    PubMed

    Alaghehmand, Homayoon; Nezhad Nasrollah, Fatemeh; Nokhbatolfoghahaei, Hanieh; Fekrazad, Reza

    2016-01-01

    Introduction: The aim of this study was to compare the micro-shear bond strength of composite resin on superficial and deep dentin after conditioning with phosphoric acid and Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser. Methods: Thirty human molars were selected, roots were removed and crowns were bisected to provide a total of 60 half-crowns. Specimens were ground to expose superficial and deep dentin. Samples were assigned to six groups: (1) AS (acid etching of superficial dentin); (2) AD (acid etching of deep dentin); (3) LS (Er:YAG laser irradiation on superficial dentin); (4) LD (Er:YAG laser irradiation on deep dentin); (5) LAS (Er:YAG laser irradiation on superficial dentin followed by acid etching); (6) LAD (Er:YAG laser irradiation on deep dentin followed by acid etching) The adhesive protocol was performed. Samples were thermocycled and micro-shear bond strength was tested to failure. The data were submitted to statistical analysis with one-way analysis of variance (ANOVA) and Tukey post hoc test. Results: The AS group, demonstrated the greatest amount of micro-shear bond strength. Statistical analysis showed a decrease in bond strength in laser-treated groups which was more significant for deep dentin. Conclusion: Preparation of dentin with laser did not improve bonding to superficial and deep dentin.

  5. An In Vitro Comparison of the Bond Strength of Composite to Superficial and Deep Dentin, Treated With Er:YAG Laser Irradiation or Acid-Etching

    PubMed Central

    Alaghehmand, Homayoon; Nezhad Nasrollah, Fatemeh; Nokhbatolfoghahaei, Hanieh; Fekrazad, Reza

    2016-01-01

    Introduction: The aim of this study was to compare the micro-shear bond strength of composite resin on superficial and deep dentin after conditioning with phosphoric acid and Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser. Methods: Thirty human molars were selected, roots were removed and crowns were bisected to provide a total of 60 half-crowns. Specimens were ground to expose superficial and deep dentin. Samples were assigned to six groups: (1) AS (acid etching of superficial dentin); (2) AD (acid etching of deep dentin); (3) LS (Er:YAG laser irradiation on superficial dentin); (4) LD (Er:YAG laser irradiation on deep dentin); (5) LAS (Er:YAG laser irradiation on superficial dentin followed by acid etching); (6) LAD (Er:YAG laser irradiation on deep dentin followed by acid etching) The adhesive protocol was performed. Samples were thermocycled and micro-shear bond strength was tested to failure. The data were submitted to statistical analysis with one-way analysis of variance (ANOVA) and Tukey post hoc test. Results: The AS group, demonstrated the greatest amount of micro-shear bond strength. Statistical analysis showed a decrease in bond strength in laser-treated groups which was more significant for deep dentin. Conclusion: Preparation of dentin with laser did not improve bonding to superficial and deep dentin. PMID:28144437

  6. The effect of antidiuretic hormone on solute flows in mammalian collecting tubules

    PubMed Central

    Schafer, James A.; Andreoli, Thomas E.

    1972-01-01

    These experiments were intended to evaluate the antidiuretic hormone (ADH)-dependent reflection coefficients of urea, sucrose, and NaCl in cortical and outer medullary collecting tubules isolated from mammalian kidney. In one group of experiments, the ADH-dependent osmotic water flows, when the perfusing solutions contained hypotonic NaCl solutions, were indistinguishable from control observations when either urea or sucrose replaced, in part, NaCl in isotonic bathing solutions (cortical collecting tubules). Similarly, both in cortical and outer medullary collecting tubules exposed to ADH, there was zero net osmotic volume flow when a portion of the NaCl in the bathing and/or perfusing solutions was replaced by either sucrose or urea, so long as the perfusing and bathing solutions were isosmolal. Taken together, these observations suggest that the ADH-dependent reflection coefficients of NaCl, urea, and sucrose, in these tubules, were identical. Since the effective hydrodynamic radii of urea and sucrose are, respectively, 1.8 and 5.2 A, it is likely that σi, for urea, sucrose, and NaCl, was unity. In support of this, the diffusion permeability coefficient (PDi cm sec-1) of urea was indistinguishable from zero. Since the limiting sites for urea penetration were the luminal interfaces of the tubules, these data are consistent with the view that ADH increases diffusional water flow across such interfaces. Images PMID:5057132

  7. Comparative assessment of hardening of demineralized dentin under lining materials using an ultramicroindentation system.

    PubMed

    Schmidlin, Patrick R; Zehnder, Matthias; Imfeld, Thomas; Swain, Michael V

    2007-10-01

    The aim of the current in vitro study was to evaluate the influence of three lining materials with a reported mineralizing capacity on hardness and elasticity of demineralized dentin. Four standardized microcavities were prepared in exposed dentin surfaces of 16 extracted human molars each. Dentin was demineralized in 0.5M EDTA for 2 h. One microcavity was left empty. The others were filled with a resin-modified glass ionomer cement (RMGIC), a bioactive glass S53P4 suspension, and a prototype Ca-PO(4) cement. Teeth were then immersed in deionized water or simulated oral fluid. After 3 weeks, hardness and composite elastic modulus of the dentin subjacent to the microcavities were assessed under wet conditions using the ultramicroindentation system (UMIS). After immersion in deionized water, there was no significant improvement of the mechanical properties of dentin irrespective of the material applied beforehand, indicating a lack of direct material effects. Exposure to simulated oral fluid resulted in significantly (p < 0.05) higher hardness and composite elastic modulus values of the dentin subjacent to empty microcavities and counterparts lined with bioactive glass compared to corresponding dentin under the RMGIC. UMIS profiles showed little variance.

  8. 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.

  9. Effectiveness of simplified dentin bonding systems.

    PubMed

    Imai, T; Itoh, K; Tani, C; Manabe, A; Yamashita, T; Hisamitsu, H; Wakumoto, S

    1998-03-01

    The effectiveness of newly developed commercial dentin bonding systems (SB, MB II and KB) was evaluated by measuring the contraction gap width of a resin composite restored into a cylindrical dentin cavity prepared in an extracted human molar and by measuring the tensile bond strength to the flat dentin surface. In addition, calcium loss during dentin conditioning was analyzed using electron microanalyses. An experimental dentin bonding system composed of EDTA conditioning, GM solution priming and a bonding agent containing 10-MDP was employed as a control in which it was presumed that contraction gap formation was prevented completely. However, gap formation was observed using the three commercial simplified dentin bonding systems. SEM observation showed that the gap was formed between the resin composite and the top surface of the dentin cavity wall indicating that the fracture occurred at the adhesive interface, but never inside the dentin nor inside the resin composite.

  10. Discerning the role of mechanosensors in regulating proximal tubule function.

    PubMed

    Raghavan, Venkatesan; Weisz, Ora A

    2016-01-01

    All cells in the body experience external mechanical forces such as shear stress and stretch. These forces are sensed by specialized structures in the cell known as mechanosensors. Cells lining the proximal tubule (PT) of the kidney are continuously exposed to variations in flow rates of the glomerular ultrafiltrate, which manifest as changes in axial shear stress and radial stretch. Studies suggest that these cells respond acutely to variations in flow by modulating their ion transport and endocytic functions to maintain glomerulotubular balance. Conceptually, changes in the axial shear stress in the PT could be sensed by three known structures, namely, the microvilli, the glycocalyx, and primary cilia. The orthogonal component of the force produced by flow exhibits as radial stretch and can cause expansion of the tubule. Forces of stretch are transduced by integrins, by stretch-activated channels, and by cell-cell contacts. This review summarizes our current understanding of flow sensing in PT epithelia, discusses challenges in dissecting the role of individual flow sensors in the mechanosensitive responses, and identifies potential areas of opportunity for new study.

  11. Bioengineered kidney tubules efficiently excrete uremic toxins

    PubMed Central

    Jansen, J.; Fedecostante, M.; Wilmer, M. J.; Peters, J. G.; Kreuser, U. M.; van den Broek, P. H.; Mensink, R. A.; Boltje, T. J.; Stamatialis, D.; Wetzels, J. F.; van den Heuvel, L. P.; Hoenderop, J. G.; Masereeuw, R.

    2016-01-01

    The development of a biotechnological platform for the removal of waste products (e.g. uremic toxins), often bound to proteins in plasma, is a prerequisite to improve current treatment modalities for patients suffering from end stage renal disease (ESRD). Here, we present a newly designed bioengineered renal tubule capable of active uremic toxin secretion through the concerted action of essential renal transporters, viz. organic anion transporter-1 (OAT1), breast cancer resistance protein (BCRP) and multidrug resistance protein-4 (MRP4). Three-dimensional cell monolayer formation of human conditionally immortalized proximal tubule epithelial cells (ciPTEC) on biofunctionalized hollow fibers with maintained barrier function was demonstrated. Using a tailor made flow system, the secretory clearance of human serum albumin-bound uremic toxins, indoxyl sulfate and kynurenic acid, as well as albumin reabsorption across the renal tubule was confirmed. These functional bioengineered renal tubules are promising entities in renal replacement therapies and regenerative medicine, as well as in drug development programs. PMID:27242131

  12. Comparative effects of the water accommodated fraction of three oils on mussels. 2. Quantitative alterations in the structure of the digestive tubules.

    PubMed

    Cajaraville, M P; Marigómez, J A; Díez, G; Angulo, E

    1992-05-01

    1. Mussels have been exposed to the water accommodated fraction (WAF) of Ural and Maya crude oils and of a lubricant oil for 91 days and the digestive gland structure has been studied (a) by planimetry, to calculate the mean epithelial thickness (MET), the mean diverticular radius (MDR) and the mean luminal radius (MLR) of the digestive tubules and (b) by subjective tubule grading, to determine the relative (%) occurrence of the different tubule types found in the digestive gland (holding, absorpting, disintegrating, reconstituting and necrotic tubules). 2. Exposure to the 3 types of WAF leads to lowered MET and MET/MDR values, and concomitant higher MLR/MET values. In the case of lubricant- and Ural-WAF exposures, MDR decreases significantly at increasing exposure-doses. 3. Exposure to oil WAFs leads to decreased percentages of holding and absorpting tubules. This decrease is concomitant with an increase of disintegrating tubules in lubricant- and Ural-WAF exposures, and with an increase of regenerating tubules in the Maya-WAF exposure. 4. The statistical significance of the differences found between control and exposed mussels is better at Day 21 than at any other further sampling day (35, 77 and 91). 5. Multiple correlation coefficients between all the percentages of tubule types and each planimetric parameter present an excellent statistical significance.

  13. Dentin-like tissue formation and biomineralization by multicellular human pulp cell spheres in vitro

    PubMed Central

    2014-01-01

    Introduction Maintaining or regenerating a vital pulp is a preferable goal in current endodontic research. In this study, human dental pulp cell aggregates (spheres) were applied onto bovine and human root canal models to evaluate their potential use as pre-differentiated tissue units for dental pulp tissue regeneration. Methods Human dental pulp cells (DPC) were derived from wisdom teeth, cultivated into three-dimensional cell spheres and seeded onto bovine and into human root canals. Sphere formation, tissue-like and mineralization properties as well as growth behavior of cells on dentin structure were evaluated by light microscopy (LM), confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Results Spheres and outgrown cells showed tissue-like properties, the ability to merge with other cell spheres and extra cellular matrix formation; CLSM investigation revealed a dense network of actin and focal adhesion contacts (FAC) inside the spheres and a pronounced actin structure of cells outgrown from the spheres. A dentin-structure-orientated migration of the cells was shown by SEM investigation. Besides the direct extension of the cells into dentinal tubules, the coverage of the tubular walls with cell matrix was detected. Moreover, an emulation of dentin-like structures with tubuli-like and biomineral formation was detected by SEM- and EDX-investigation. Conclusions The results of the present study show tissue-like behavior, the replication of tubular structures and the mineralization of human dental pulp spheres when colonized on root dentin. The application of cells in form of pulp spheres on root dentin reveals their beneficial potential for dental tissue regeneration. PMID:24946771

  14. Study on the potential inhibition of root dentine wear adjacent to fluoride-containing restorations.

    PubMed

    Turssi, Cecilia Pedroso; Hara, Anderson Takeo; Domiciano, Silvia Jorge; Serra, Mônica Campos

    2008-01-01

    The purpose of this in vitro study was to determine whether the vicinity of root dentine that had been restored with fluoride-releasing materials was at reduced risk for erosive/abrasive wear compared to root dentine restored with a non-fluoride-containing material. According to a randomized complete block design, standardized cavities prepared on the surface of 150 bovine root dentine slabs were restored with glass-ionomer cement, resin-modified glass ionomer, polyacid-modified resin composite, fluoride-containing or conventional composite. Specimens were coated with two layers of an acid-resistant nail varnish exposing half of the dentine surface and half of the restoration. Subsequently, specimens were either eroded in an acidic drink or left uneroded, then exposed to artificial saliva and abraded in a toothbrushing machine. Wear depth in the vicinity of restorations was quantified by a stylus profilometer, based on the nonabraded areas surrounding the erosion/abrasion region. Two-way ANOVA did not demonstrate significant interaction between restoratives and eroded-uneroded dentine (p=0.5549) nor significant difference among restorative materials (p=0.8639). Tukey's test ascertained that the wear depth was higher for eroded than for uneroded groups. Fluoride-releasing materials seemed to negligibly inhibit wear in the vicinity of restored root dentine subjected to erosive/abrasive challenges.

  15. Effect of Phosphoric Acid on the Degradation of Human Dentin Matrix

    PubMed Central

    Tezvergil-Mutluay, A.; Mutluay, M.; Seseogullari-Dirihan, R.; Agee, K.A.; Key, W.O.; Scheffel, D.L.S.; Breschi, L.; Mazzoni, A.; Tjäderhane, L.; Nishitani, Y.; Tay, F.R.; Pashley, D.H.

    2013-01-01

    This study determined if dentin proteases are denatured by phosphoric acid (PA) used in etch-and-rinse dentin adhesives. Dentin beams were completely demineralized with EDTA for 30 days. We “acid-etched” experimental groups by exposing the demineralized dentin beams to 1, 10, or 37 mass% PA for 15 sec or 15 min. Control beams were not exposed to PA but were incubated in simulated body fluid for 3 days to assay their total endogenous telopeptidase activity, by their ability to solubilize C-terminal crosslinked telopeptides ICTP and CTX from insoluble dentin collagen. Control beams released 6.1 ± 0.8 ng ICTP and 0.6 ± 0.1 ng CTX/mg dry-wt/3 days. Positive control beams pre-incubated in p-aminophenylmercuric acetate, a compound known to activate proMMPs, released about the same amount of ICTP peptides, but released significantly less CTX. Beams immersed in 1, 10, or 37 mass% PA for 15 sec or 15 min released amounts of ICTP and CTX similar to that released by the controls (p > 0.05). Beams incubated in galardin, an MMP inhibitor, or E-64, a cathepsin inhibitor, blocked most of the release of ICTP and CTX, respectively. It is concluded that PA does not denature endogenous MMP and cathepsin activities of dentin matrices. PMID:23103634

  16. Bonding efficacy of an acetone/based etch-and-rinse adhesive after dentin deproteinization

    PubMed Central

    Aguilera, Fátima S.; Osorio, Raquel; Osorio, Estrella; Moura, Pedro

    2012-01-01

    Objectives: to evaluate the effect of sodium hypochlorite (NaOCl) treatment on dentin bonding by means of shear bond strength (SBS) measurements when using Prime&Bond NT (PB NT) adhesive. Ultrastructure of the interfaces was examined by scanning electron microscopy (SEM). Study design: Extracted human third molars were sectioned and ground to expose flat surfaces of superficial or deep dentin. Specimens were randomly assigned to two equal groups, and bonded as follows: (1) according to the manufacturers’ directions, after 35% H3PO4 etching, (2) 5% NaOCl treated for 2 minutes, after 35% H3PO4 etching. Each sample was embedded in a Watanabe shear test assembly for a single plane lap shear. After PB NT bonding, specimens were stored in water for 24 h at 37ºC and thermocycled (500x). Samples were tested in shear to failure using a universal testing machine at 0.75 mm/min. Data were analyzed with ANOVA and Newman-Keuls multiple comparison test procedures. Two samples of each group were randomly selected to investigate the morphologic aspect of the resin/dentin interface with SEM. Results: After etching and after aqueous sodium hypochlorite (NaOClaq) application, SBS values were similar on superficial than deep dentin (p>0.05). SEM findings shows for H3PO4 etching conditioned samples a detectable hybrid layer and long resin tags; for NaOCl treated specimens, it may be observed a non apparent hybrid layer, and the adhesive contact directly with the neck of the cylindrical resin tags. Conclusions: The use of 5% NaOCl for 2 min after dentin demineralization when PB NT was employed did not improve the bond strength to dentin, probably due to nanofiller content and/or oxidative changes on collagen-depleted dentin. Key words:Sodium hypochlorite, shear bond strength, SEM, Prime&Bond NT, superficial dentin, deep dentin. PMID:22322501

  17. Influence of eugenol-containing temporary cement on efficacy of dentin-bonding systems.

    PubMed

    Peutzfeldt, A; Asmussen, E

    1999-02-01

    Zinc oxide-eugenol (ZOE) cements are widely used as temporary filling materials. However, eugenol has earlier been shown to have a detrimental effect on both resin composites and dentin-bonding systems. The aim of the present in vitro study was to examine whether ZOE cement would also reduce the efficacy of relatively new dentin-bonding systems. This was done by determination of gap formation around resin composite fillings in dentin cavities and of bond strength of resin composite to enamel and dentin. The tooth surfaces involved were either freshly cut, or had been exposed to a ZOE cement (IRM) or to a non-ZOE cement (Cavit) for 7 d before application of a dentin-bonding system (Gluma CPS or Scotchbond Multi-Purpose Plus) and a resin composite (Z100). Gap formation was assessed in a light microscope on 20-min-old fillings and expressed as wall-to-wall contraction (the width of the maximum marginal gap in % of the cavity diameter). Bond strength was measured in shear on 1-d-old specimens. The mean values of wall-to-wall contraction were 0.06-0.09% with Scotchbond Multi-Purpose Plus and 0.20-0.24% with Gluma CPS. The mean values of bond strength to enamel were 22-25 MPa for Scotchbond Multi-Purpose Plus and 20-23 MPa for Gluma CPS, and to dentin were 20-22 MPa for Scotchbond Multi-Purpose Plus and 13-14 MPa for Gluma CPS. The use of Scotchbond Multi-Purpose Plus resulted in higher bond strength to dentin and less wall-to-wall contraction than did Gluma CPS. No differences were found in either wall-to-wall contraction or in bond strength between the three groups for either dentin-bonding system. Thus, the ZOE cement did not influence the efficacy of two relatively new dentin-bonding systems.

  18. Tubules of plant reoviruses exploit tropomodulin to regulate actin-based tubule motility in insect vector

    PubMed Central

    Chen, Qian; Zhang, Linghua; Zhang, Yanshuang; Mao, Qianzhuo; Wei, Taiyun

    2017-01-01

    Plant reoviruses are known to exploit virion-packaging tubules formed by virus-encoding non-structural proteins for viral spread in insect vectors. Tubules are propelled by actin-based tubule motility (ABTM) to overcome membrane or tissue barriers in insect vectors. To further understand which insect factors mediate ABTM, we utilized yeast two-hybrid and bimolecular fluorescence complementation assays to test interactions between tubule protein Pns10 of rice dwarf virus (RDV), a plant reovirus, and proteins of its insect vector, the leafhopper Nephotettix cincticeps. Tropomodulin (Tmod), vitellogenin, and lipophorin precursor of N. cincticep displayed positive and strong interaction with Pns10, and actin-associated protein Tmod interacted with Pns10 in pull-down assay and the co-immunoprecipitation system. Further, we determined Pns10 tubules associated with Tmod in cultured cells and midgut of N. cincticep. The expression dynamic of Tmod was consistent with that of Pns10 and the fluctuation of RDV accumulation. Knockdown of Tmod inhibited the Pns10 expression and viral accumulation, thus decreasing the viruliferous rates of leafhopper. These results suggested that Tmod was involved in viral spread by directly interacting with Pns10 tubules, finally promoting RDV infection. This study provided direct evidence of plant reoviruses utilizing an actin-associated protein to manipulate ABTM in insect vectors, thus facilitating viral spread. PMID:28067229

  19. The effects of extracts of chewing sticks (Salvadora persica) on healthy and periodontally involved human dentine: a SEM study.

    PubMed

    Almas, K

    2001-01-01

    The popularity and availability of chewing sticks (Salvadora persica) in the Asia, Middle East and Africa make them a commonly used oral hygiene tool in those societies. Salvador persica chewing stick called miswak is frequently used in Saudi Arabia. The antimicrobial effects of miswak has been well documented. The aim of this study is to find our the effect of aqueous extracts of miswak on healthy and periodontally involved human dentine with Scanning Electron Microscopy (SEM) in vitro. 25% aqueous extract of freshly prepared miswak solution was used for the study. Twelve human premolars teeth (6 healthy and 6 with periodontal disease) recently extracted for orthodontic and periodontal reasons were used. 24 SEM specimens were prepared and treated with miswak extract with different conditions e.g. soaking and burnishing with miswak extract. Soaking the healthy and periodontally diseased root dentine in miswak extract resulted in partial removal of smear layer and occlusion of dentinal tubules was observed in dentine specimens burnished with miswak solution. Further research is needed to evaluate the effect of aqueous extract of miswak on etched human dentine at higher concentrations.

  20. The effect of IDS (immediate dentin sealing) on dentin bond strength under various thermocycling periods

    PubMed Central

    Leesungbok, Richard; Lee, Sang-Min; Park, Su-Jung; Lee, Suk-Won; Lee, Do Yun; Im, Byung-Jin

    2015-01-01

    PURPOSE The purpose of this study was to find out the effect of immediate dentin sealing (IDS) on bond strength of ceramic restoration under various thermocycling periods with DBA (dentin bonding agent system). MATERIALS AND METHODS Fifty freshly extracted human mandibular third molars were divided into 5 groups (1 control and 4 experimental groups) of 10 teeth. We removed enamel layer of sound teeth and embedded them which will proceed to be IDS, using All Bond II. A thermocycling was applied to experimental groups for 1, 2, 7, 14 days respectively and was not applied to control group. IPS Empress II for ceramic was acid-etched with ceramic etchant (9.5% HF) and silane was applied. Each ceramic disc was bonded to specimens with Duo-link, dual curable resin cement by means of light curing for 100 seconds. After the cementation procedures, shear bond strength measurement and SEM analysis of the fractured surface were done. The data were analyzed with a one-way ANOVA and Tukey multiple comparison test (α=.05). RESULTS There were no statistically significant differences between 4 experimental groups and control group, however the mean value started to decrease in group 7d, and group 14d showed the lowest mean bond strength in all groups. Also, group 7d and 14d showed distinct exposed dentin and collapsed hybrid layer was observed in SEM analysis. CONCLUSION In the present study, it can be concluded that ceramic restorations like a laminate veneer restoration should be bonded using resin cement within one week after IDS procedure. PMID:26140174

  1. Bond strength comparison of amalgam repair protocols using resin composite in situations with and without dentin exposure.

    PubMed

    Ozcan, Mutlu; Schoonbeek, Geert; Gökçe, Bülent; Cömlekoglu, Erhan; Dündar, Mine

    2010-01-01

    The replacement of defective amalgam restorations leads to loss of tooth material and weakens the tooth, creating an increased risk of cusp fracture. The repair of such defects is a minimal intervention technique. The current study compared the repair bond strengths of a resin composite to amalgam and an amalgam-dentin complex after various surface conditioning methods. The specimens (N = 50) consisted of sound human canines with cylindrical preparations (diameter: 2.3 mm, depth: 3 mm) with amalgam-dentin complex (N = 30, n = 10/per group) and two groups with amalgam only (N = 20, n = 10/per group). The teeth were embedded in auto-polymerized polymethylmethacrylate (PMMA). The preparations were filled with non-Gamma 2 amalgam. The enamel was removed to expose dentin. The specimens with the amalgam-dentin complex were randomly assigned to one of the following conditioning methods: Group 1: Silicacoating amalgam, etching dentin, silane application on amalgam, primer/bonding on dentin, opaquer on amalgam, resin composite on both; Group 2: Etching dentin, silicacoating amalgam, silane application on amalgam, primer/bonding on dentin, opaquer on amalgam, resin composite on both and Group 3: Etching dentin, primer/bonding on dentin, opaquer, resin composite. The specimens with only amalgam were assigned to one of the following conditioning methods: Group 4: Silicacoating, silane application, opaquer, resin composite and Group 5: Opaquer, resin composite. For the two control groups, where no dentin was involved (Groups 4 and 5), bonding was achieved only on amalgam and Group 5 had no conditioning. The specimens were kept in water at 37 degrees C for five weeks before bond strength (MPa +/- SD) testing (Universal Testing Machine). After debonding, the failure types were analyzed. The results were significantly affected by the surface conditioning method (ANOVA). Only dentin conditioning (Group 3) showed the highest bond strength (39.9 +/- 14). The unconditioned control

  2. Interpretation of male rat renal tubule tumors.

    PubMed Central

    Rodgers, I S; Baetcke, K P

    1993-01-01

    Based on an analysis of recent scientific studies, a Technical Panel of the U.S. Environmental Protection Agency's (EPA) Risk Assessment Forum recently advised EPA risk assessors against using information on certain male rat renal tubule tumors to assess human risk under conditions specified in a new Forum report. Risk assessment approaches generally assume that chemicals producing tumors in laboratory animals are a potential cancer hazard to humans. For most chemicals, including classical rodent kidney carcinogens such as N-ethyl-N-hydroxyethylnitrosamine, this extrapolation remains appropriate. Some chemicals, however, induce accumulation of alpha 2u-globulin (alpha 2u-g), a low molecular weight protein, in the male rat kidney. The alpha 2u-g accumulation initiates a sequence of events that appears to lead to renal tubule tumor formation. Female rats and other laboratory mammals administered the same chemicals do not accumulate low molecular weight protein in the kidney, and they do not develop renal tubule tumors. Because humans appear to be more like other laboratory animals than like the male rat, in this special situation, the male rat is not a good model for assessing human risk. The Forum report stresses the need for full scrutiny of a substantial set of data to determine when it is reasonable to presume that renal tumors in male rats are linked to a process involving alpha 2u-g accumulation and to select appropriate procedures for estimating human risks under such circumstances. PMID:7517352

  3. Role of proximal tubules in the pathogenesis of kidney disease.

    PubMed

    Nakhoul, Nazih; Batuman, Vecihi

    2011-01-01

    The proximal tubules make up a significant portion of the kidneys; proximal tubule epithelial cells are the most populous cell type in the kidney, and carry out diverse regulatory and endocrine functions where numerous transporters are located. Under normal circumstances, more than two thirds of filtered salt and water, and all filtered bicarbonate is reabsorbed in the proximal tubule. A number of inherited and acquired acid-base and tubule disorders are linked to impaired transporters in the proximal tubule cells. Equally important is the intrinsic immune characteristics of proximal tubule cells that give them the ability to also function as immune responders to a wide range of immunologic, ischemic or toxic injury. It is therefore not surprising that proximal tubule-related phenomena are closely related to the pathogenesis of a vast array of kidney diseases. Many kidney diseases, acute and chronic, first manifest with proximal tubule disorders. Recent insight into molecular characteristics of transport functions in the proximal tubules, and the recognition that proximal tubule cells possess intrinsic immune responses have contributed to an improved understanding of important areas in nephrology, such as Fanconi's syndrome, renal tubular acidosis, phosphate wasting syndromes, Dent's disease, cystinuria and other amino acid transport disorders, acute kidney injury, and the role of proximal tubules in progressive kidney disease. Megalin/ cubilin-mediated endocytosis by proximal tubule cells of increased quantities of filtered proteins (protein overloading) in glomerular diseases appears to evoke cell stress responses resulting in increased inflammatory cytokines leading to tubulointerstitial inflammation and fibrosis. Finally, the proximal tubule may be the site of both active vitamin D synthesis through the action of 1-α-hydroxylase, and the site where erythropoietin synthesis takes place. Thus, proximal tubule injury also contributes to two distressing

  4. NANOLEAKAGE PHENOMENON ON DEPROTEINIZED HUMAN DENTIN

    PubMed Central

    Duarte, Patrícia de Britto Pereira Garcia; da Silva, Eduardo Moreira

    2007-01-01

    Objective: The purpose of this study was to evaluate the influence of dentin deproteinization on the nanoleakage phenomenon. Material and Methods: Class V cavities were prepared in 12 human molars with cervical margins located in dentin. The cavities were assigned to 2 groups (n=6) according to dentin treatment: Group I - dentin treated in accordance with the manufacturer’s instructions and Group II - dentin treated following the manufacturer’s instructions + 10% NaOCl. Each group was sub-divided into three groups, according to the DBS (dentin bonding system) used: Scotchbond Multi Purpose (SBMP), Prime & Bond NT (PB) and Clearfil SE Bond (SE), which were applied according to manufacturer’s instructions. The cavities were restored with composite resin, and the specimens were immersed in a tracer agent (AgNO3 50%) for 24 h. The teeth were sectioned buccolingually through the center of the restorations, and nanoleakage pattern was evaluated by scanning electron microscopy (SEM) using the backscattered electron image mode. Results: SEM analysis showed different nanoleakage patterns for each DBS. Irrespective of dentin treatments, all SBMP specimens showed nanoleakage. SE did not show any nanoleakage with both dentin treatments used. PB showed nanoleakage within the hybrid layer only in Group I. Conclusions: The influence of dentin deproteinization on the nanoleakage phenomenon was dependent on dentin bonding system formulation and bonding strategies. PMID:19089146

  5. Comparison of dentin root canal permeability and morphology after irradiation with Nd:YAG, Er:YAG, and diode lasers.

    PubMed

    Esteves-Oliveira, Marcella; de Guglielmi, Camila A B; Ramalho, Karen Müller; Arana-Chavez, Victor E; de Eduardo, Carlos Paula

    2010-09-01

    The aim of this study was to compare the effects of Nd:YAG, Er:YAG, and diode lasers on the morphology and permeability of root canal walls. The three laser wavelengths mentioned interact differently with dentin and therefore it is possible that the permeability changes caused will determine different indications during endodontic treatment. Twenty-eight human single-rooted teeth were instrumented up to ISO 40 and divided into four groups: group C, control (GC), non-laser irradiated; group N (GN), irradiated with Nd:YAG laser; group E (GE), with Er:YAG laser and group D (GD) with diode laser. After that, the roots were filled with a 2% methylene blue dye, divided into two halves and then photographed. The images were analyzed using Image J software and the percentage of dye penetration in the cervical, middle, and apical root thirds were calculated. Additional scanning electron microscopy (SEM) analyses were also performed. The analysis of variance (ANOVA) showed significant permeability differences between all groups in the middle and cervical thirds (p < 0.05). The Tukey test showed that in the cervical third, GN presented means of dye penetration statistically significantly lower than all of the other groups. In the middle third, GE and GD showed statistically higher dye penetration means than GC and GN. SEM analysis showed melted surfaces for GN, clean wall surfaces with open dentinal tubules for GE, and mostly obliterated dentinal tubules for GD. Er:YAG (2,094 nm) laser and diode laser (808 nm) root canal irradiation increase dentinal permeability and Nd:YAG (1,064 nm) laser decreases dentin permeability, within the studied parameters.

  6. SGLT2 Inhibitors: Glucotoxicity and Tumorigenesis Downstream the Renal Proximal Tubule?

    PubMed

    Bertinat, Romina; Nualart, Francisco; Yáñez, Alejandro J

    2016-08-01

    At present, diabetes mellitus is the main cause of end-stage renal disease. Effective glycaemic management is the most powerful tool to delay the establishment of diabetic complications, such as diabetic kidney disease. Together with reducing blood glucose levels, new anti-diabetic agents are expected not only to control the progression but also to restore known defects of the diabetic kidney. Sodium-glucose co-transporter 2 (SGLT2) inhibitors are promising anti-diabetic agents that reduce hyperglycaemia by impairing glucose reabsorption in proximal tubule of the kidney and increasing glucosuria. SGLT2 inhibitors have shown to reduce glucotoxicity in isolated proximal tubule cells and also to attenuate expression of markers of overall kidney damage in experimental animal models of diabetes, but the actual renoprotective effect for downstream nephron segments is still unknown and deserves further attention. Here, we briefly discuss possible undesired effects of enhanced glucosuria and albuminuria in nephron segments beyond the proximal tubule after SGLT2 inhibitor treatment, offering new lines of research to further understand the renoprotective action of these anti-diabetic agents. Strategies blocking glucose reabsorption by renal proximal tubule epithelial cells (RPTEC) may be protective for RPTEC, but downstream nephron segments will still be exposed to high glucose and albumin levels through the luminal face. The actual effect of constant enhanced glucosuria over distal nephron segments remains to be established. J. Cell. Physiol. 231: 1635-1637, 2016. © 2015 Wiley Periodicals, Inc.

  7. A Fourier Transform Infrared Spectroscopy Analysis of Carious Dentin from Transparent Zone to Normal Zone

    PubMed Central

    Liu, Y.; Yao, X.; Liu, Y.W.; Wang, Y.

    2015-01-01

    It is well known that caries invasion leads to the differentiation of dentin into zones with altered composition, collagen integrity and mineral identity. However, understanding of these changes from the fundamental perspective of molecular structure has been lacking so far. In light of this, the present work aims to utilize Fourier transform infrared spectroscopy (FTIR) to directly extract molecular information regarding collagen's and hydroxyapatite's structural changes as dentin transitions from the transparent zone (TZ) into the normal zone (NZ). Unembedded ultrathin dentin films were sectioned from carious teeth, and an FTIR imaging system was used to obtain spatially resolved FTIR spectra. According to the mineral-to-matrix ratio image generated from large-area low-spectral-resolution scan, the TZ, the NZ and the intermediate subtransparent zone (STZ) were identified. High-spectral-resolution spectra were taken from each zone and subsequently examined with regard to mineral content, carbonate distribution, collagen denaturation and carbonate substitution patterns. The integrity of collagen's triple helical structure was also evaluated based on spectra collected from demineralized dentin films of selected teeth. The results support the argument that STZ is the real sclerotic layer, and they corroborate the established knowledge that collagen in TZ is hardly altered and therefore should be reserved for reparative purposes. Moreover, the close resemblance between the STZ and the NZ in terms of carbonate content, and that between the STZ and the TZ in terms of being A-type carbonate-rich, suggest that the mineral that initially occludes dentin tubules is hydroxyapatite newly generated from odontoblastic activities, which is then transformed into whitlockite in the demineralization/remineralization process as caries progresses. PMID:24556607

  8. Molecular and morphological surface analysis: effect of filling pastes and cleaning agents on root dentin

    PubMed Central

    DAINEZI, Vanessa Benetello; IWAMOTO, Alexsandra Shizue; MARTIN, Airton Abrahão; SOARES, Luís Eduardo Silva; HOSOYA, Yumiko; PASCON, Fernanda Miori; PUPPIN-RONTANI, Regina Maria

    2017-01-01

    Abstract The quality of the dentin root is the most important factor for restoration resin sealing and drives the outcome of endodontic treatment. Objective This study evaluated the effect of different filling pastes and cleaning agents on the root dentin of primary teeth using Fourier-transformed Raman spectroscopy (FT-Raman), micro energy-dispersive X-ray fluorescence (µ-EDXRF) and scanning electron microscopic (SEM) analysis. Material and Methods Eighty roots of primary teeth were endodontically prepared and distributed into 4 groups and filled according to the following filling pastes: Control-no filling (CP), Calen®+zinc oxide (CZ), Calcipex II® (CII), Vitapex® (V). After seven days, filling paste groups were distributed to 4 subgroups according to cleaning agents (n=5): Control-no cleaning (C), Ethanol (E), Tergenform® (T), 35% Phosphoric acid (PA). Then, the roots were sectioned and the dentin root sections were internally evaluated by FT-Raman, µ-EDXRF and SEM. Data was submitted to two-way ANOVA and Tukey tests (α=0.05). Results Regarding filling pastes, there was no significant difference in organic content. CP provided the lowest calcium values and, calcium/phosphoric ratio (Ca/P), and the highest phosphoric values. For cleaning agents there was no difference in organic content when compared to the C; however, T showed significantly higher calcium and Ca/P than PA. All groups showed similar results for phosphorus. The dentin smear layer was present after use of the cleaning agents, except PA. Conclusion The filling pastes changed the inorganic content, however they did not change the organic content. Cleaning agents did not alter the inorganic and organic content. PA cleaned and opened dentin tubules. PMID:28198982

  9. Detection and measurement of tubulitis in renal allograft rejection

    NASA Astrophysics Data System (ADS)

    Hiller, John B.; Chen, Qi; Jin, Jesse S.; Wang, Yung; Yong, James L. C.

    1997-04-01

    Tubulitis is one of the most reliable signs of acute renal allograft rejection. It occurs when mononuclear cells are localized between the lining tubular epithelial cells with or without disruption of the tubular basement membrane. It has been found that tubulitis takes place predominantly in the regions of the distal convoluted tubules and the cortical collecting system. The image processing tasks are to find the tubule boundaries and to find the relative location of the lymphocytes and epithelial cells and tubule boundaries. The requirement for accuracy applies to determining the relative locations of the lymphocytes and the tubule boundaries. This paper will show how the different sizes and grey values of the lymphocytes and epithelial cells simplify their identification and location. Difficulties in finding the tubule boundaries image processing will be illustrated. It will be shown how proximate location of epithelial cells and the tubule boundary leads to distortion in determination of the calculated boundary. However, in tubulitis the lymphocytes and the tubule boundaries are proximate.In these cases the tubule boundary is adequately resolved and the image processing is satisfactory to determining relativity in location. An adaptive non-linear anisotropic diffusion process is presented for image filtering and segmentation. Multi-layer analysis is used to extract lymphocytes and tubulitis from images. This paper will discuss grading of tissue using the Banff system. The ability to use computer to use computer processing will be argued as obviating problems of reproducability of values for this classification. This paper will also feature discussion of alternative approaches to image processing and provide an assessment of their capability for improving the identification of the tubule boundaries.

  10. Brushing abrasion of eroded dentin after application of sodium fluoride solutions.

    PubMed

    Attin, T; Zirkel, C; Hellwig, E

    1998-01-01

    The aim of the present in vitro study was to evaluate the influence of sodium fluoride solutions on brushing abrasion of eroded dentin. Dentin specimens were prepared from 60 bovine incisors. The specimens were embedded in acrylic resin, ground flat, polished and subsequently covered with tape exposing an area of 1.8 mm x 10.0 mm in the center of the exposed dentin. The samples were alternatingly stored in a demineralizing solution (5 min) and a remineralizing solution (1 min) for 5 times. The erosive soft drink Sprite light(R) served as a demineralizing solution and artificial saliva was used as a remineralizing solution. Prior to storage in artificial saliva 15 specimens were each treated for 1 min with 250 and 2,000 ppm fluoride solution, respectively. Fifteen specimens were treated with distilled water instead of the fluoride solution (= eroded controls). The remaining samples were neither eroded with the soft drink nor fluoridated (= uneroded controls). After each immersion in artificial saliva the specimens were submitted to abrasion in a toothbrushing machine. After 5 demineralization-remineralization brushing cycles the total amount of tooth wear due to erosion and subsequent abrasion was profilometrically evaluated. Statistical analysis revealed the significantly lowest wear in the uneroded controls and the highest amount of abrasion in the eroded controls. Application of the fluoride solutions increased the wear resistance of the eroded dentin specimens, showing significantly better protection by the high-concentration compared to the low-concentration solution. The susceptibility to abrasion of the eroded dentin specimens treated with the high-concentration fluoride solution did not differ significantly from the uneroded dentin samples. It is concluded that application of 2,000 ppm sodium fluoride solutions immediately before toothbrushing significantly reduces abrasion of eroded dentin in vitro.

  11. Influence of laser etching on enamel and dentin bond strength of Silorane System Adhesive.

    PubMed

    Ustunkol, Ildem; Yazici, A Ruya; Gorucu, Jale; Dayangac, Berrin

    2015-02-01

    The aim of this in vitro study was to evaluate the shear bond strength (SBS) of Silorane System Adhesive to enamel and dentin surfaces that had been etched with different procedures. Ninety freshly extracted human third molars were used for the study. After the teeth were embedded with buccal surfaces facing up, they were randomly divided into two groups. In group I, specimens were polished with a 600-grit silicon carbide (SiC) paper to obtain flat exposed enamel. In group II, the overlying enamel layer was removed and exposed dentin surfaces were polished with a 600-grit SiC paper. Then, the teeth in each group were randomly divided into three subgroups according to etching procedures: etched with erbium, chromium:yttrium-scandium-gallium-garnet laser (a), etched with 35% phosphoric acid (b), and non-etched (c, control). Silorane System Adhesive was used to bond silorane restorative to both enamel and dentin. After 24-h storage in distilled water at room temperature, a SBS test was performed using a universal testing machine at a crosshead speed of 1 mm/min. The data were analyzed using two-way ANOVA and Bonferroni tests (p < 0.05). The highest SBS was found after additional phosphoric acid treatment in dentin groups (p < 0.05). There were no statistically significant differences between the laser-etched and non-etched groups in enamel and dentin (p > 0.05). The SBS of self-etch adhesive to dentin was not statistically different from enamel (p > 0.05). Phosphoric acid treatment seems the most promising surface treatment for increasing the enamel and dentin bond strength of Silorane System Adhesive.

  12. Validation of a Cariogenic Biofilm Model to Evaluate the Effect of Fluoride on Enamel and Root Dentine Demineralization

    PubMed Central

    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. PMID:26731743

  13. Effect of ultrasonic streaming on intra-dentinal disinfection and penetration of calcium hydroxide paste in endodontic treatment

    PubMed Central

    ARIAS, Marcela Paola Castro; MALIZA, Amanda Garcia Alves; MIDENA, Raquel Zanin; GRAEFF, Márcia Sirlene Zardin; DUARTE, Marco Antonio Húngaro; de ANDRADE, Flaviana Bombarda

    2016-01-01

    ABSTRACT Objective The antimicrobial effect of ultrasonic agitation of calcium hydroxide (CH) pastes in infected bovine dentin and their penetrability were evaluated using confocal laser scanning microscopy (CLSM) and microbiological culture. Material and Methods Fifty-two bovine teeth were infected with Enterococcus faecalis using a new contamination protocol; then they received CH paste and were divided into groups with or without ultrasound. Ultrasonic agitation was conducted for 1 min with a plain point insert. After 15 d, the CLSM analyzed the viable and dead bacteria with Live and Dead assay. The dentinal wall debris was collected by burs, and the colony forming units (CFU/mL) were counted. The penetrability of the paste inside dentinal tubules was tested using the B-rodamine dye. Results The calcium hydroxide paste showed better results with the use of ultrasonic agitation (p<0.05). Conclusion The ultrasonic agitation of CH paste increased its antimicrobial action and was responsible for intradentinal penetration with the fulfilment of the tubules. PMID:28076462

  14. Comparative study of dentine permeability after apicectomy and surface treatment with 9.6 microm TEA CO2 and Er:YAG laser irradiation.

    PubMed

    Gouw-Soares, S; Stabholz, A; Lage-Marques, J L; Zezell, D M; Groth, E B; Eduardo, C P

    2004-04-01

    Failure of apicectomies is generally attributed to dentine surface permeability as well as to the lack of an adequate marginal sealing of the retrofilling material, which allows the percolation of microorganisms and their products from the root canal system to the periodontal region, thus compromising periapical healing. The purpose of this study was to evaluate dentine and the marginal permeability after apicectomy and surface treatment with 9.6 micro m TEA CO(2) or Er:YAG 2.94 micro m laser irradiation. Sixty-five single rooted human endodontically treated teeth were divided into five experimental groups: group I (control), apicectomy with high speed bur; group II, similar procedure to that of group I, followed by dentinal surface treatment with 9.6 micro m CO(2) laser; group III, similar procedure to group I followed by dentinal surface treatment with Er:YAG laser 2.94 micro m; group IV, apicectomy and surface treatment with CO(2) 9.6 micro m laser; and group V, apicectomy and surface treatment with Er:YAG laser 2.94 micro m. The analysis of methylene blue dye infiltration through the dentinal surface and the retrofilling material demonstrated that the samples from the groups that were irradiated with the lasers showed significantly lower infiltration indexes than the ones from the control group. These results were compatible with the structural morphological changes evidenced through SEM analysis. Samples from groups II and IV (9.6 micro m CO(2)) showed clean smooth surfaces, fusion, and recrystallized dentine distributed homogeneously throughout the irradiated area sealing the dentinal tubules. Samples from groups III and V (Er:YAG 2.94 micro m) also presented clean surfaces, without smear layer, but roughly compatible to the ablationed dentine and without evidence of dentinal tubules. Through the conditions of this study, the Er:YAG 2.94 micro m and the 9.6 micro m CO(2) laser used for root canal resection and dentine surface treatment showed a reduction of

  15. Inhibition of enzymatic degradation of adhesive-dentin interfaces.

    PubMed

    De Munck, J; Van den Steen, P E; Mine, A; Van Landuyt, K L; Poitevin, A; Opdenakker, G; Van Meerbeek, B

    2009-12-01

    Adhesive procedures activate dentin-associated matrix metalloproteinases (MMPs), and so iatrogenically initiate bond degradation. We hypothesized that adding MMP inhibitors to adhesive primers may prevent this endogenous enzymatic degradation, thereby improving bond durability. A non-specific MMP inhibitor (chlorhexidine) and a MMP-2/9-specific inhibitor (SB-3CT) were admixed to the primers of an etch & rinse and a self-etch adhesive, both considered as gold-standard adhesives within their respective categories. For dentin powder exposed to the adhesives under clinical application conditions, gelatin zymography revealed the release of MMP-2 (not of MMP-9) by the etch & rinse adhesive, while no release of enzymes could be detected for the mild self-etch adhesive, most likely because of its limited dentin demineralization effect. The built-in MMP inhibitors appeared effective in reducing bond degradation only for the etch & rinse adhesive, and not for the self-etch adhesive. Water sorption of adhesive interfaces most likely remains the principal mechanism of bond degradation, while endogenous enzymes appear to contribute to bond degradation of only etch & rinse adhesives.

  16. Modification of the dentin surface by using carbon nanotubes.

    PubMed

    Akasaka, Tsukasa; Nakata, Keiko; Uo, Motohiro; Watari, Fumio

    2009-01-01

    Recent studies have shown that carbon nanotubes (CNTs) can be used as biomedical materials because of their unique properties. CNTs effect nucleation of hydroxyapatite, because of which considerable interest has been generated regarding the use of CNTs in dentistry. However, there are only a few reports on the use of CNTs as dental materials. In this study, we investigated the changes induced in the surfaces of tooth slices by the application of a coating of CNTs by observing CNT-coated tooth slices both macroscopically as well as under a scanning electron microscope. Further, we investigated the effect of CNT coating on the tensile bond strength of dentin adhesives. CNTs adhered easily to the tooth surfaces when tooth slices were suspended in a CNT-dispersed solution. Interestingly, it was observed that CNTs selectively adhered to the surfaces of dentin and cementum, possibly by adhering to their exposed collagen fibers. In addition, the CNT coating did not affect the tensile bond strength of dentin adhesives. These results indicate that coating of the teeth with CNTs can be a possible application of CNTs as dental materials.

  17. Extracellular matrix proteins of dentine.

    PubMed

    Butler, W T; Ritchie, H H; Bronckers, A L

    1997-01-01

    Bone and dentine extracellular matrix proteins are similar, consisting primarily of type I collagen, acidic proteins and proteoglycans. Although collagen forms the lattice for deposition of calcium and phosphate for formation of carbonate apatite, the non-collagenous proteins are believed to control initiation and growth of the crystals. Despite this similarity, dentine contains three unique proteins apparently absent from bone and other tissue: dentine phosphophoryn (DPP), dentine matrix protein 1 (DMP1) and dentine sialoprotein (DSP). DPP and DMP1 are acidic phosphoproteins probably involved in the control of mineralization processes. DPP may localize in gap regions of collagen and initiate apatite crystal formation by binding large quantities of calcium in a conformation that promotes this process. Extensive studies have been conducted in our laboratory on the nature, biosynthesis, localization and gene structure of DSP. Immunolocalization studies showed that rat DSP, a 53 kDa sialic acid-rich glycoprotein, was synthesized by young and mature odontoblasts, and by dental pulp cells and pre-ameloblasts, but not by ameloblasts, osteoblasts, chondrocytes or other cell types. The cDNA sequence indicated that DSP was a 366-residue protein with several potential N-glycosylation sites, as well as phosphorylation sites, but that the amino acid sequence was dissimilar to that of other known proteins. Northern blot analysis detected several mRNA species near 4.6 and 1.5 kb, indicative of alternative splicing events. Evidence for two DSP genes was obtained, further complicating this picture. Recent in situ hybridization studies utilizing rat and mouse molars and incisors indicated that DSP mRNA was expressed by young odontoblasts and odontoblasts in animals of all ages. Transcripts were also observed in pre-ameloblasts. The expression of DSP mRNA ceased when these cells matured to become secretory ameloblasts. DSP transcripts were not detected in osteoblasts or other cell

  18. Excretion of alkaloids by malpighian tubules of insects.

    PubMed

    Maddrell, S H; Gardiner, B O

    1976-04-01

    Nicotine is transported at high rates by Malpighian tubules of larvae of Manduca sexta, Pieris brassicae and Rhodnius prolixus and the transport persists in the absence of alkaloid from the diet. In the fluid-secreting portion of Rhodnius tubules this transport is not coupled to ion transport, nor is it dependent on the physiological state of the animal. The transport, which can occur against a steep electrochemical gradient, shows saturation kinetics with a maximal rate of 700 pmol. min-1 per tubule and is half saturated at 2-3 mM. Nicotine transport independent of ion movements also occurs in the lower resorptive parts of Rhodnius tubules. Both portions of Rhodnius tubules can transport morphine and atropine. These alkaloids and nicotine compete with one naother and are presumed to be carried by the smae transport system. Nicotine transport in Rhodnius was unaffected by organic anions, such as amaranth and benzyl penicillin, or by the organic anion transport inhibitor, probenecid. Fluid secretion in 5-HT-stimulated tubules was reduced by atropine and nicotine, probably by blocking the 5-HT receptors. The Malpighian tubules of adult Calliphora erythrocephala and Musca domestica remove nicotine from bathing solutions, an unknown metabolic accumulating in the tubules. Adult P. brassicae and M. sexta do not exhibit transport of nicotine by their Malpighian tubules.

  19. Nonlinear analysis of lipid tubules by nonlocal beam model.

    PubMed

    Shen, Hui-Shen

    2011-05-07

    Postbuckling, nonlinear bending and nonlinear vibration analyses are presented for lipid tubules. The lipid tubule is modeled as a nonlocal micro/nano-beam which contains small scale effect. The material properties are assumed to be size-dependent. The governing equation is solved by a two-step perturbation technique. The numerical results reveal that the small scale parameter e₀a reduces the postbuckling equilibrium paths, the static large deflections and natural frequencies of lipid tubules. In contrast, it increases the nonlinear to linear frequency ratios slightly for the lipid tubule with immovable end conditions.

  20. Comparative evaluation of the effect of chlorhexidine and Aloe barbadensis Miller (Aloe vera) on dentin stabilization using shear bond testing

    PubMed Central

    Sinha, Dakshita Joy; Jaiswal, Natasha; Vasudeva, Agrima; Garg, Paridhi; Tyagi, Shashi Prabha; Chandra, Priyanka

    2016-01-01

    Introduction: The main objective of adhesive dentistry is to create an effective, durable union between the tooth structure and restorative material. However, degradation of adhesive dentine interface remains largely responsible for the relatively short lifetime of tooth colored resin restoration. Aim: The aim of the study is to compare the dentin collagen stabilization property of Chlorhexidine (CHX) and Aloe barbadensis Miller using shear bond strength testing. Materials and Methods: Occlusal reduction was done in sixty extracted human mandibular molars to expose the mid coronal dentin and divided into three groups n = 20. Following the surface pretreatment (Group 1 = control, Group 2 = CHX, Group 3 = Aloevera), dentine bonding agent and composite resin were applied and cured. The specimens were then subjected to shear bond strength testing. Results: From the results analyzed, it was noted that there was statistically significant difference between the groups Control and CHX and Control and A. barbadensis Miller (P < 0.05), specifically the values of Control < CHX and Control < A. barbadensis Miller (P < 0.05). However, there was no statistically significant difference between CHX and A. barbadensis Miller (P > 0.05). Hence, the following result for the shear bond strengths to dentin was obtained: Control < CHX ≈ A. barbadensis Miller. Conclusion: CHX and A. barbadensis Miller, as pretreatment agents of acid demineralized dentin collagen, has no adverse effect on the immediate shear bond strength of a two-step etch and rinse adhesive to dentin. PMID:27656056

  1. Application of Diode Laser in the Treatment of Dentine Hypersensitivity

    PubMed Central

    Gojkov-Vukelic, Mirjana; Hadzic, Sanja; Zukanovic, Amila; Pasic, Enes; Pavlic, Veriva

    2016-01-01

    Introduction: Dentine hypersensitivity is characterized by acute, sharp pain arising from the exposed dentine, most commonly in response to thermal, tactile, or chemical stimuli, and which cannot be linked to any other pathological changes in the tooth or the environment. Therapy uses various impregnating agents in the form of solutions or gels and, in more recent times, laser. Aim: The aim of this research was to examine the effects of treatment of hypersensitive dental cervix with diode laser. Materials and Methods: The study included 18 patients with 82 sensitive teeth. The degree of dentine hypersensitivity was evaluated by visual analogue scale (VAS), and the treatment was carried out by application of low-power diode laser over the span of three visits, which depended on the initial sensitivity. Results: There is a significant difference in VAS values measured at the onset of treatment (baseline) and immediately after the first laser treatment (t=9.275; p=0.000), after 7 days, after the second laser treatment (14 days) (t=7.085, p=0.000), as well as after 14 days and the third laser treatment (t=5.517, p=0.000), which confirms the effectiveness of this therapeutic procedure. The results showed a reduction of hypersensitivity in response to tactile stimulus with a probe after the third treatment, even with teeth whose value on the VAS was very high at the beginning of treatment (baseline). Conclusion: Within the scope of the conducted study, laser therapy has provided extremely safe and effective results in the treatment of cervical dentine hypersensitivity. PMID:28210023

  2. Cytotoxic effects of thiamethoxam in the midgut and malpighian tubules of Africanized Apis mellifera (Hymenoptera: Apidae).

    PubMed

    Catae, Aline Fernanda; Roat, Thaisa Cristina; De Oliveira, Regiane Alves; Nocelli, Roberta Cornélio Ferreira; Malaspina, Osmar

    2014-04-01

    Due to its expansion, agriculture has become increasingly dependent on the use of pesticides. However, the indiscriminate use of insecticides has had additional effects on the environment. These products have a broad spectrum of action, and therefore the insecticide affects not only the pests but also non-target insects such as bees, which are important pollinators of agricultural crops and natural environments. Among the most used pesticides, the neonicotinoids are particularly harmful. One of the neonicotinoids of specific concern is thiamethoxam, which is used on a wide variety of crops and is toxic to bees. Thus, this study aimed to analyze the effects of this insecticide in the midgut and Malpighian tubule cells of Africanized Apis mellifera. Newly emerged workers were exposed until 8 days to a diet containing a sublethal dose of thiamethoxam equal to 1/10 of LC₅₀ (0.0428 ng a.i./l L of diet). The bees were dissected and the organs were processed for transmission electron microscopy. The results showed that thiamethoxam is cytotoxic to midgut and Malpighian tubules. In the midgut, the damage was more evident in bees exposed to the insecticide on the first day. On the eighth day, the cells were ultrastructurally intact suggesting a recovery of this organ. The Malpighian tubules showed pronounced alterations on the eighth day of exposure of bees to the insecticide. This study demonstrates that the continuous exposure to a sublethal dose of thiamethoxam can impair organs that are used during the metabolism of the insecticide.

  3. A Comparative Study of Ion Diffusion from Calcium Hydroxide with Various Herbal Pastes through Dentin

    PubMed Central

    Dhirawani, Rajesh B; Marya, Jayant; Dhirawani, Vrinda; Kumar, Vijayendra

    2017-01-01

    Aim The aim of this study was to evaluate the diffusion ability of ions through dentinal tubules of different nonalcoholic calcium hydroxide-containing herbal pastes and compare it with the calcium hydroxide paste prepared with saline. Materials and methods A total of 36 single-rooted premolar teeth were used in this study. The tooth crowns were removed and the root canals were prepared. Depending on the vehicle to be used for preparing calcium hydroxide pastes, six groups were made: Group I: Ca(OH)2 saline paste (control group), group II: Ca(OH)2 papaya latex paste, group III: Ca(OH)2 coconut water paste, group IV: Ca(OH)2 Ashwagandha (Withania somnifera) paste, group V: Ca(OH)2 Tulsi (Ocimum tenuiflorum) paste, and group VI: Ca(OH)2 garlic (Allium sativum) paste. After biomechanical preparation, calcium hydroxide herbal paste dressings were applied and sealed with resin-based cement. The teeth were placed in containers with deionized water, and the pH of the water was measured at regular intervals over 3, 24, 72, and 168 hours. Results We observed that all herbal pastes allowed the diffusion of ions, but pastes prepared with Ashwagandha and papaya latex showed more ion diffusion after 168 hours and marked increase in pH, depicting better support for calcium hydroxide action. Conclusion We conclude that Ashwagandha and papaya latex allow better diffusion of calcium hydroxide through den-tinal tubules, thus enhancing its action, and advise its use as a vehicle for placing intracanal medicament. How to cite this article Dausage P, Dhirawani RB, Marya J, Dhirawani V, Kumar V. A Comparative Study of Ion Diffusion from Calcium Hydroxide with Various Herbal Pastes through Dentin. Int J Clin Pediatr Dent 2017;10(1):41-44. PMID:28377654

  4. Ptychographic X-ray nanotomography quantifies mineral distributions in human dentine

    NASA Astrophysics Data System (ADS)

    Zanette, I.; Enders, B.; Dierolf, M.; Thibault, P.; Gradl, R.; Diaz, A.; Guizar-Sicairos, M.; Menzel, A.; Pfeiffer, F.; Zaslansky, P.

    2015-03-01

    Bones are bio-composites with biologically tunable mechanical properties, where a polymer matrix of nanofibrillar collagen is reinforced by apatite mineral crystals. Some bones, such as antler, form and change rapidly, while other bone tissues, such as human tooth dentine, develop slowly and maintain constant composition and architecture for entire lifetimes. When studying apatite mineral microarchitecture, mineral distributions or mineralization activity of bone-forming cells, representative samples of tissue are best studied at submicrometre resolution while minimizing sample-preparation damage. Here, we demonstrate the power of ptychographic X-ray tomography to map variations in the mineral content distribution in three dimensions and at the nanometre scale. Using this non-destructive method, we observe nanostructures surrounding hollow tracts that exist in human dentine forming dentinal tubules. We reveal unprecedented quantitative details of the ultrastructure clearly revealing the spatially varying mineralization density. Such information is essential for understanding a variety of natural and therapeutic effects for example in bone tissue healing and ageing.

  5. The association between Nd:YAG laser and desensitizing dentifrices for the treatment of dentin hypersensitivity.

    PubMed

    Cunha, Sandra Ribeiro; Garófalo, Stephanie Assimakopoulos; Scaramucci, Taís; Zezell, Denise Maria; Aranha, Ana Cecilia Corrêa

    2017-03-14

    This study aims to evaluate the association between Nd:YAG laser (with and without a photoabsorber) and two desensitizing dentifrices containing 15% NovaMin or 8% arginine, as potential treatments for dentin hypersensitivity (DH). DH was simulated by EDTA application for 2 min. Specimens were then analyzed with an environmental scanning electron microscope (ESEM) to ensure open dentin tubules (ODT), counted by using ImageJ software. Specimens were randomized into eight groups (n = 10): Laser (L), Laser+Photoabsorber (LP), Arginine (A), Arginine+Laser (AL), Arginine+Laser+Photoabsorber (ALP), NovaMin (N), NovaMin+Laser (NL), and NovaMin+Laser+Photoabsorber (NLP). Laser irradiation was performed with 1 W, 100 mJ, 10 Hz, ≅85 J/cm(2); 4 irradiations of 10 s each, with 10 s intervals between them. After treatment, specimens were again analyzed by ESEM and submitted to erosive/abrasive cycling for 5 days. A final ESEM analysis was performed. Data were analyzed with two-way repeated measure ANOVA and Tukey tests (α = 0.05). After treatment, groups N, NL, and NLP presented the lower number of ODT, but they did not different from LP, ALP, and AL. Group A presented the highest number of ODT and it did not differ from group L. Groups L, AL, ALP, and LP presented intermediate results, without differing from each other. After cycling, group A presented the highest number of ODT and did not differ significantly from the other groups, except NLP. None of the associations tested presented better tubule occlusion than NovaMin by itself. Arginine was the only treatment that presented improved tubule occlusion when associated with Nd:YAG laser.

  6. Matricellular molecules and odontoblast progenitors as tools for dentin repair and regeneration

    PubMed Central

    Goldberg, M.; Lacerda-Pinheiro, S.; Priam, F.; Jegat, N.; Six, N.; Bonnefoix, M.; Septier, D.; Chaussain-Miller, C.; Veis, A.; Denbesten, P.; Poliard, A.

    2010-01-01

    This review summarizes the in vivo experiments carried out by our group after implantation of bioactive molecules (matricellular molecules) into the exposed pulp of the first maxillary molar of the rat or the mandibular incisor of rats and mice. We describe the cascade of recruitment, proliferation and terminal differentiation of cells involved in the formation of reparative dentin. Cloned immortalized odontoblast progenitors were also implanted in the incisors and in vitro studies aimed at revealing the signaling pathways leading from undifferentiated progenitors to fully differentiated polarized cells. Together, these experimental approaches pave the way for controlled dentin regenerative processes and repair. PMID:18157557

  7. 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

  8. Microtensile dentin bond strength of fifth with five seventh-generation dentin bonding agents after thermocycling: An in vitro study

    PubMed Central

    Poptani, Bruhvi; Gohil, K. S.; Ganjiwale, Jaishree; Shukla, Manisha

    2012-01-01

    Objectives: The objective of this in vitro study was to compare the microtensile dentin bond strength (μTBS) of five seventh-generation dentin bonding agents (DBA) with fifth-generation DBA before and after thermocycling. Materials and Methods: Ten extracted teeth were assigned to fifth generation control group (optibond solo) and each of the five experimental groups namely, Group I (G-Bond) ,Group II (S3 Clearfil), Group III (One Coat 7.0), Group IV (Xeno V), and Group V (Optibond all in one). The crown portions of the teeth were horizontally sectioned below the central groove to expose the dentin. The adhesive resins from all groups were bonded to the teeth with their respective composites. Specimens of sizes 1 × 1 × 6 mm3 were obtained. Fifty specimens that bonded to dentin from each group were selected. Twenty-five of the specimens were tested for debonding without thermocycling and the remaining were subjected to thermocycling followed by μTBS testing. The data were analyzed with one-way ANOVA and Dunnett's-test for comparison with the reference group(Vth Generation). Results: There was no significant difference (P > 0.05) between the fifth- and seventh-generation adhesives before and after thermocycling. The results of our study showed significantly higher value (P < 0.05) of μTBS of seventh-generation Group II (Clearfil S3) compared to the fifth-generation before and after thermocycling. Conclusion: The study demonstrated that the Clearfil S3 bond had the highest μTBS values. In addition, of the five tested seventh-generation adhesive resins were comparable to the fifth-generation DBA. PMID:23230355

  9. Hydration and dynamic fatigue of dentin.

    PubMed

    Arola, D; Zheng, W

    2006-04-01

    An experimental investigation on the dynamic fatigue response of dentin was conducted to examine the influence of stress rate on the strength and energy to fracture. Rectangular beams were prepared from the coronal dentin of bovine maxillary molars and subjected to four-point flexure to failure. The dentin beams were examined in the fully hydrated and dehydrated condition at stress rates (sigma) ranging from 0.01 to 100 MPa/s. Results for the hydrated dentin showed that the flexure strength, energy to fracture, and flexure modulus all increased with increasing stress rate; the flexure strength increased from 100 MPa ((sigma) = 0.01 MPa/s) to 250 MPa ((sigma) = 100 MPa/s). In contrast, the elastic modulus and strength of the dehydrated dentin decreased with increasing stress rate; the flexural strength of the dehydrated dentin deceased from 170 MPa ((sigma) = 0.01 MPa/s) to 100 MPa ((sigma) = 100 MPa/s). While the hydrated dentin behaved more like a brittle material at low stress rates, the strain to fracture was found to be nearly independent of (sigma). According to the experimental results, restorative conditions that cause development of static stresses within the tooth could promote a decrease in the damage tolerance of dentin.

  10. Dentinal innervation of impacted human third molars.

    PubMed

    Lilja, J; Fagerberg-Mohlin, B

    1984-12-01

    Five totally impacted third molars were studied in the transmission electron microscope for the presence of nervous structures in the dentin before eruption. In contradiction to earlier studies available, nervous structures were found in the predentin and the dentin of the impacted third molars in different parts of the crown and also in the predentin of the root.

  11. 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

  12. Effect of MTAD on the shear bond strength of self-etch adhesives to dentin

    PubMed Central

    Mortazavi, Vajihesadat; Khademi, Abbasali; Khosravi, Kazem; Fathi, Mohammadhossein; Ebrahimi–Chaharom, Mohammadesmaeil; Shahnaseri, Shirin; Khalighinejad, Navid; Badrian, Hamid

    2012-01-01

    Background: As the use of different irrigants to eliminate residual debris and smear layer in the field of endodontic is unavoidable, by considering the effect of irrigants on the bond strength of resin composite restorations, this study was designed to evaluate the effect of a mixture of a tetracycline isomer, an acid, and a detergent (MTAD) on the shear bond strength of two self-etch adhesives, Clearfil SE Bond and Adper Prompt L- Pop to dentin. Materials and Methods: The crowns of 80 extracted premolars were transversally sectioned to expose dentin. Flat dentin surfaces were wet abraded with 320-grit abrasive paper and randomly assigned to eight groups according to two self-etch adhesive and four dentin surface treatments: direct application over smear layer (no treatment), etching with 35% phosphoric acid for 15s, 1 min 5.25% NaOCl/1 min MTAD and 20min 1.3% NaOCl/5min MTAD. Shear bond strength was tested 24 h after storage in distilled water at 37°C in incubator. Data were analyzed using one-way ANOVA followed by duncan post-hoc (α=0.05). Results: Phosphoric acid etching prior to SE Bond application significantly decreased the shear bond strength to dentin (P<0.05). Application of MTAD clinical protocol (20min 1.3% NaOCl/5min MTAD) did not significantly decrease the shear bond strength of self-etch adhesives to dentin (P=0.745) Conclusions: Based on the results of present investigation, it seems that the use of clinical protocol of 1.3% NaOCl as a root canal irrigant and a 5-min application of MTAD as a final rinse to remove the smear layer has no adverse effect on the shear bond strength of self-etch adhesives to dentin. PMID:22363359

  13. Non-thermal atmospheric plasma brush induces HEMA grafting onto dentin collagen

    PubMed Central

    Chen, Mingsheng; Zhang, Ying; Dusevich, Vladimir; Liu, Yi; Yu, Qingsong; Wang, Yong

    2014-01-01

    Objective Non-thermal atmospheric plasma (NTAP) brush has been regarded as a promising technique to enhance dental interfacial bonding. However, the principal enhancement mechanisms have not been well identified. In this study, the effect of non-thermal plasmas on grafting of HEMA, a typical dental monomer, onto dentin collagen thin films was investigated. Methods Human dentin was sectioned into 10-um-thick films. After total demineralization in 0.5 M EDTA solution for 30 min, the dentin collagen films were water-rinsed, air-dried, treated with 35 wt% HEMA aqueous solution. The films were then subject to plasma-exposure under a NTAP brush with different time (1–8 min) / input power (5–15 w). For comparison, the dentin collagen films were also treated with the above HEMA solution containing photo-initiators, then subject to light-curing. After plasma-exposure or light-curing, the HEMA-collagen films were rinsed in deionized water, and then examined by FTIR spectroscopy and TEM. Results The FITR results indicated that plasma-exposure could induce significant HEMA grafting onto dentin collagen thin films. In contrast, light-curing led to no detectable interaction of HEMA with dentin collagen. Quantitative IR spectral analysis (i.e., 1720/3075 or 749/3075, HEMA/collagen ratios) further suggested that the grafting efficacy of HEMA onto the plasma-exposed collagen thin films strongly depended on the treatment time and input power of plasmas. TEM results indicated that plasma treatment did not alter collagen’s banding structure. Significance The current study provides deeper insight into the mechanism of dental adhesion enhancement induced by non-thermal plasmas treatment. The NTAP brush could be a promising method to create chemical bond between resin monomers and dentin collagen. PMID:25458523

  14. Effects of adsorbed and templated nanosilver in mesoporous calcium-silicate nanoparticles on inhibition of bacteria colonization of dentin.

    PubMed

    Fan, Wei; Wu, Daming; Tay, Franklin R; Ma, Tengjiao; Wu, Yujie; Fan, Bing

    2014-01-01

    Mesoporous calcium-silicate nanoparticles (MCSNs) are advanced biomaterials for controlled drug delivery and mineralization induction. Nanosilver-incorporated MCSNs (Ag-MCSNs) were prepared in the present study using both the adsorption and template methods. Both versions of Ag-MCSNs showed characteristic morphology of mesoporous materials and exhibited sustained release of ions over time. In antibacterial testing against planktonic Enterococcus faecalis, Ag-MCSNs showed significantly better antibacterial effects when compared with MCSNs (P<0.05). The Ag-MCSNs aggregated on the dentin surface of root canal walls and infiltrated into dentinal tubules after ultrasound activation, significantly inhibiting the adherence and colonization of E. faecalis on dentin (P<0.05). Despite this, Ag-MCSNs with templated nanosilver showed much lower cytotoxicity than Ag-MCSNs with adsorbed nanosilver (P<0.05). The results of the present study indicated that nanosilver could be incorporated into MCSNs using the template method. The templated nanosilver could release silver ions and inhibit the growth and colonization of E. faecalis both in the planktonic form and as biofilms on dentin surfaces as absorbed nanosilver. Templated Ag-MCSNs may be developed into a new intracanal disinfectant for root canal disinfection due to their antibacterial ability and low cytotoxicity, and as controlled release devices for other bioactive molecules to produce multifunctional biomaterials.

  15. Contact pulsed Nd:YAG ablation of human dentin: ablation rates and tissue effects

    NASA Astrophysics Data System (ADS)

    Harris, David M.; Yessik, Michael J.

    1994-09-01

    Dentin from freshly extracted human teeth was exposed to flashlamp pumped Nd:YAG pulses (100 microsecond(s) duration, 50 - 200 mJ/pulse) delivered through a flat cut fiberoptic in contact with the dentin surface. Ablation depth and volume were measured optically and confirmed with electron microscope morphometrics. Ablation depth increased with force applied at the fiber tip up to 5 - 10 g. Above this ablation depths were insensitive to applied force. Craters made in dental stone were deeper and narrower than those made in normal dentin. Ablation depths per pulse and volumes per pulse decrease as the number of pulses increase. This is more prominent for 200 mJ pulses. At 60 mJ the ablation depths are the same from 10 to 100 Hz repetition rates, although qualitative changes (collateral damage) are greater at higher repetition rates. A progressive increase in collateral damage is seen from the 1st through the 200th pulse.

  16. Malpighian Tubules as Novel Targets for Mosquito Control

    PubMed Central

    Piermarini, Peter M.; Esquivel, Carlos J.; Denton, Jerod S.

    2017-01-01

    The Malpighian tubules and hindgut are the renal excretory tissues of mosquitoes; they are essential to maintaining hemolymph water and solute homeostasis. Moreover, they make important contributions to detoxifying metabolic wastes and xenobiotics in the hemolymph. We have focused on elucidating the molecular mechanisms of Malpighian tubule function in adult female mosquitoes and developing chemical tools as prototypes for next-generation mosquitocides that would act via a novel mechanism of action (i.e., renal failure). To date, we have targeted inward rectifier potassium (Kir) channels expressed in the Malpighian tubules of the yellow fever mosquito Aedes aegypti and malaria mosquito Anopheles gambiae. Inhibition of these channels with small molecules inhibits transepithelial K+ and fluid secretion in Malpighian tubules, leading to a disruption of hemolymph K+ and fluid homeostasis in adult female mosquitoes. In addition, we have used next-generation sequencing to characterize the transcriptome of Malpighian tubules in the Asian tiger mosquito Aedes albopictus, before and after blood meals, to reveal new molecular targets for potentially disrupting Malpighian tubule function. Within 24 h after a blood meal, the Malpighian tubules enhance the mRNA expression of genes encoding mechanisms involved with the detoxification of metabolic wastes produced during blood digestion (e.g., heme, NH3, reactive oxygen species). The development of chemical tools targeting these molecular mechanisms in Malpighian tubules may offer a promising avenue for the development of mosquitocides that are highly-selective against hematophagous females, which are the only life stage that transmits pathogens. PMID:28125032

  17. Developmental Changes in Proximal Tubule Tight Junction Proteins

    PubMed Central

    HADDAD, MAHA; LIN, FANGMING; DWARAKANATH, VANGIPURAM; CORDES, KIMBERLY; BAUM, MICHEL

    2014-01-01

    We demonstrated previously that neonatal proximal tubules have a lower passive paracellular permeability to chloride ions and higher resistance than that of adult proximal tubules. In addition, administration of thyroid hormone to neonates, before the normal maturational increase in serum thyroid hormone levels, prematurely accelerates the developmental increase in chloride permeability to adult levels. To test the hypothesis that there is a maturational change in tight junction proteins and that thyroid hormone mediates these changes, we examined the two known tight junction proteins present in proximal tubules, occludin and claudin 2. Using immunoblot and immunohistochemistry, we demonstrated that claudin 2 has a 4-fold greater abundance in neonatal proximal tubules than in adult tubules. Occludin, however, has a 4-fold greater expression in adult tubules than in neonatal tubules. Administration of thyroid hormone to neonates did not affect claudin 2 expression, occludin expression, or the transepithelial resistance in rat proximal tubule cells in vitro. In conclusion, there are postnatal maturational changes in tight junction proteins. The factors that cause these maturational changes are unknown but unlikely to be due solely to the maturational increase in thyroid hormone. PMID:15585672

  18. Isosmotic volume reabsorption in rat proximal tubule

    PubMed Central

    1980-01-01

    A theoretical model incorporation both active and passive forces has been developed for fluid reabsorption from split oil droplets in rat intermediate and late proximal tubule. Of necessity, simplifying assumptions have been introduced; we have assumed that the epithelium can be treated as a single membrane and that the membrane "effective" HCO3 permeability is near zero. Based on this model with its underlying assumptions, the following conclusions are drawn. Regardless of the presence or absence of active NaCl transport, fluid reabsorption from the split oil droplet is isosmotic. The reabsorbate osmolarity can be affected by changes in tubular permeability parameters and applied forces but is not readily altered from an osmolarity essentially equal to that of plasma. In a split droplet, isosmotic flow need not be a special consequence of active Na transport, is not the result of a particular set of permeability properties, and is not merely a trivial consequence of a very high hydraulic conductivity; isosmotic flow can be obtained with hydraulic conductivity nearly an order of magnitude lower than that previously measured in the rat proximal convoluted tubule. Isosmotic reabsorption is, in part, the result of the interdependence of salt and water flows, their changing in parallel, and thus their ratio, the reabsorbate concentration being relatively invariant. Active NaCl transport can cause osmotic water flow by reducing the luminal fluid osmolarity. In the presence of passive forces the luminal fluid can be hypertonic to plasma, and active NaCl transport can still exert its osmotic effect on volume flow. There are two passive forces for volume flow: the Cl gradient and the difference in effective osmotic pressure; they have an approximately equivalent effect on volume flow. Experimentally, we have measured volume changes in a droplet made hyperosmotic by the addition of 50 mM NaCl; the experimental results are predicted reasonably well by our theoretical model

  19. Isosmotic volume reabsorption in rat proximal tubule.

    PubMed

    Warner, R R; Lechene, C

    1980-11-01

    A theoretical model incorporation both active and passive forces has been developed for fluid reabsorption from split oil droplets in rat intermediate and late proximal tubule. Of necessity, simplifying assumptions have been introduced; we have assumed that the epithelium can be treated as a single membrane and that the membrane "effective" HCO3 permeability is near zero. Based on this model with its underlying assumptions, the following conclusions are drawn. Regardless of the presence or absence of active NaCl transport, fluid reabsorption from the split oil droplet is isosmotic. The reabsorbate osmolarity can be affected by changes in tubular permeability parameters and applied forces but is not readily altered from an osmolarity essentially equal to that of plasma. In a split droplet, isosmotic flow need not be a special consequence of active Na transport, is not the result of a particular set of permeability properties, and is not merely a trivial consequence of a very high hydraulic conductivity; isosmotic flow can be obtained with hydraulic conductivity nearly an order of magnitude lower than that previously measured in the rat proximal convoluted tubule. Isosmotic reabsorption is, in part, the result of the interdependence of salt and water flows, their changing in parallel, and thus their ratio, the reabsorbate concentration being relatively invariant. Active NaCl transport can cause osmotic water flow by reducing the luminal fluid osmolarity. In the presence of passive forces the luminal fluid can be hypertonic to plasma, and active NaCl transport can still exert its osmotic effect on volume flow. There are two passive forces for volume flow: the Cl gradient and the difference in effective osmotic pressure; they have an approximately equivalent effect on volume flow. Experimentally, we have measured volume changes in a droplet made hyperosmotic by the addition of 50 mM NaCl; the experimental results are predicted reasonably well by our theoretical model.

  20. Three-dimensional architecture of virus-packed tubule.

    PubMed

    Katayama, Sumie; Wei, Taiyun; Omura, Toshihiro; Takagi, Junichi; Iwasaki, Kenji

    2007-06-01

    When rice dwarf virus (RDV), a member of the Reoviridae family, infects leafhopper cells, formation of protruding tubules composed of nonstructural viral protein Pns 10 can be observed. We examined the three-dimensional (3D) structure of these tubules containing RDV particles using electron tomography. The thin section of RDV-infected leafhopper vector cells in monolayers was subjected to double-tilt tomography. The tomographic 3D map provides a more reliable estimation of the real dimensions of the structure compared with the 2D image of the thin section. Docking of particle models made from atomic coordinates of RDV into the tomogram revealed that the inner diameter of the tubule was close to the outer diameter of the RDV particle. Fourier-transform of the reconstituted tubule image from the purified Pns 10 protein in vitro revealed a helical structure of the tubule.

  1. Chemical Profile of the Dentin Substrate in Non-Carious Cervical Lesions

    PubMed Central

    Karan, Kunal; Yao, Xiaomei; Xu, Changqi; Wang, Yong

    2009-01-01

    Objective The molecular structural nature of the dentin substrate in non-carious cervical lesions (NCCLs) is poorly understood. This investigation characterized the chemical structure including inhomogeneities, composition, mineral crystallinity, collagen organization of normal dentin and affected dentin substrates within NCCLs using Raman micro-spectroscopic mapping/imaging. Materials and Methods Three extracted human pre-molars affected with NCCLs were selected and cavities matching the natural lesion with respect to size and location were prepared on the lingual/palatal surface of each tooth to serve as controls. The specimens were sectioned to expose the gingival and occlusal margins of the NCCLs and the control cavities. Micro-Raman spectra and imaging acquired at 1.5 micrometer spatial resolution at positions perpendicular to the lesion surfaces. Results The Raman spectra and imaging comparisons showed the distinct compositional and structural alterations in mineral and matrix components of NCCL affected dentin. A heterogeneous hyper-mineralized layer, with characteristic features such as high phosphate/low carbonate content, high degree of crystallinity and partially denatured collagen were revealed in affected dentin substrate of NCCLs. Significance Generating Raman images based on different strategies from the same data set provides a powerful means to study the structural alterations within heterogeneous dental tissues. Direct overlay of the images indicated that the changes in chemical structure and composition are synchronized. Further studies are required to understand the role that these alterations play in response to acid etching and bonding to these clinically-relevant substrates. PMID:19464050

  2. Effect of cleaning methods on bond strength of self-etching adhesive to dentin

    PubMed Central

    Bronzato, Juliana Delatorre; Cecchin, Doglas; Miyagaki, Daniela Cristina; de Almeida, José Flávio Affonso; Ferraz, Caio Cezar Randi

    2016-01-01

    Aim: The aim of this study was to investigate the influence of cleaning methods to remove zinc oxide-eugenol-based root canal sealer (Endomethasone) on the bond strength of the self-etching adhesive to dentin. Materials and Methods: Twenty crowns of bovine incisors were cut to expose the pulp chamber. A zinc oxide- and eugenol-based sealer was placed for 10 min in contact with the pulp chamber dentin. Specimens were divided into four groups according to the cleaning method of dentin used: G1, no root canal sealer (control); G2, 0.9% sodium chlorite (NaCl); G3, ethanol; and G4, followed by diamond drill. After cleaning, the teeth were restored with composite resin and Clearfil SE Bond. All specimens were sectioned to produce rectangular sticks and dentin/resin interface was submitted to microtensile bond testing. The mean bond strengths were analyzed using ANOVA/Tukey (α = 0.05). Results: G3 and G4 showed bond strengths similar to the G1 (P > 0.05). A significant decrease in the bond strength in the G2 was observed (P < 0.05). G1, G3, and G4, the predominant failure mode was the mixed type. The prevalence of adhesive failure mode was verified in the G2. Conclusion: The cleaning methods affected the bond strength of the self-etching adhesive to dentin differently. PMID:26957789

  3. Effect of Chloroform, Eucalyptol and Orange Oil Solvents on the Microhardness of Human Root Dentin

    PubMed Central

    Khedmat, Sedigheh; Hashemi, Alaleh; Dibaji, Fatemeh; Kharrazifard, Mohammad Javad

    2015-01-01

    Objectives: This study aimed to assess the effect of chloroform, eucalyptol and orange oil solvents on the microhardness of human root dentin. Materials and Methods: Sixty-eight single-rooted single-canal extracted human premolar teeth were used. Tooth crowns were separated from the roots at the cementoenamel junction (CEJ). Roots were buccolingually sectioned into mesial and distal halves. Specimens were randomly divided into 5 groups, with 20 teeth in each solvent group and 4 teeth in each control group. Primary microhardness of specimens was measured using Vickers microhardness tester. Specimens were exposed to solvents for 15 minutes and were subjected to microhardness testing again. Data were recorded and analyzed using repeated measure ANOVA. Results: No significant difference was found in dentin microhardness before and after exposure to solvents in any of the orange oil, eucalyptol, chloroform or saline groups (P=0.727). None of the experimental groups showed any significant difference in terms of dentin microhardness reduction (P=0.99) and had no significant difference with the negative control group. Conclusion: This study showed that chloroform, eucalyptol and orange oil as gutta percha solvents did not decrease the microhardness of root dentin. Thus, none of the mentioned solvents has any superiority over the others in terms of affecting dentin properties. PMID:26005451

  4. LONG-TERM BOND STRENGTH OF ADHESIVE SYSTEMS APPLIED TO ETCHED AND DEPROTEINIZED DENTIN

    PubMed Central

    Uceda-Gómez, Ninoshka; Loguercio, Alessandro Dourado; Moura, Sandra Kiss; Grande, Rosa Helena Miranda; Oda, Margareth; Reis, Alessandra

    2007-01-01

    The aim of this study was to evaluate the early and 12-month bond strength of two adhesive systems (Single Bond-SB and One Step-OS) applied to demineralized dentin (WH) and demineralized/NaOCl-treated dentin (H). Twenty flat dentin surfaces were exposed, etched, rinsed and slightly dried. For the H groups, a solution of 10% NaOCl was applied for 60 s, rinsed (15 s) and slightly dried. The adhesives were applied according to the manufacturer's instructions and composite resin crowns were incrementally constructed. After 24 h (water-37°C), the specimens was sectioned in order to obtain resin-dentin sticks (0.8 mm2). The specimens were tested in microtensile (0.5 mm/min) immediately (IM) or after 12 months of water storage (12M). The data (MPa) were subjected to ANOVA and Tukey's test (α=0.05). Only the main factors adhesive and time were significant (p=0.004 and p=0.003, respectively). SB (42.3±9.1) showed higher bond strengths than OS (33.6±11.6). The mean bond strength for IM-group (42.5±8.7) was statistically superior to 12M (33.3±11.8). The use of 10% NaOCl, after acid etching, did not improve the immediate and the long-term resin-dentin bond strength. PMID:19089183

  5. Degradation in the fatigue crack growth resistance of human dentin by lactic acid.

    PubMed

    Orrego, Santiago; Xu, Huakun; Arola, Dwayne

    2017-04-01

    The oral cavity frequently undergoes localized changes in chemistry and level of acidity, which threatens the integrity of the restorative material and supporting hard tissue. The focus of this study was to evaluate the changes in fatigue crack growth resistance of dentin and toughening mechanisms caused by lactic acid exposure. Compact tension specimens of human dentin were prepared from unrestored molars and subjected to Mode I opening mode cyclic loads. Fatigue crack growth was achieved in samples from mid- and outer-coronal dentin immersed in either a lactic acid solution or neutral conditions. An additional evaluation of the influence of sealing the lumens by dental adhesive was also conducted. A hybrid analysis combining experimental results and finite element modeling quantified the contribution of the toughening mechanisms for both environments. The fatigue crack growth responses showed that exposure to lactic acid caused a significant reduction (p≤0.05) of the stress intensity threshold for cyclic crack extension, and a significant increase (p≤0.05) in the incremental fatigue crack growth rate for both regions of coronal dentin. Sealing the lumens had negligible influence on the fatigue resistance. The hybrid analysis showed that the acidic solution was most detrimental to the extrinsic toughening mechanisms, and the magnitude of crack closure stresses operating in the crack wake. Exposing dentin to acidic environments contributes to the development of caries, but it also increases the chance of tooth fractures via fatigue-related failure and at lower mastication forces.

  6. Capacity of a hydroxyapatite–lysozyme combination against Streptococcus mutans for the treatment of dentinal caries

    PubMed Central

    Pinheiro, Sérgio Luiz; da Rocha, Nathany Nunes; Peres, Mariane de Lourdes Hernandes Martins

    2016-01-01

    Background: One current strategy for the treatment of carious lesions is the use of biomaterials with antimicrobial activity. Aims: The aim of this study was to evaluate a combination of hydroxyapatite and lysozyme for the treatment of dentinal caries by measuring Streptococcus mutans counts before carious tissue sealing, and 24 h, 1 month, and 6 months after treatment. Materials and Methods: Forty permanent third molars were selected, and flat dentin surfaces were prepared. The teeth were exposed to a cariogenic challenge with S. mutans. After challenge, the dentinal caries were collected from five specimens. The remaining specimens were treated with a mixture of hydroxyapatite and lysozyme in sodium laureth sulfate and sealed with composite resin. S. mutans counts were obtained 24 h, 1 month, and 6 months after sealing. Statistical Analysis: The results were evaluated by descriptive statistics and Wilcoxon signed-rank test. Results: a significant reduction in S. mutans (CFU/mL) was observed in dentinal lesions 1 month after treatment with hydroxyapatite/lysozyme in sodium laureth sulfate (P = 0.0254). Comparison of S. mutans counts obtained 24 h, 1 month, and 6 months after treatment revealed reductions only at the 1-month time point (P = 0.0318). Conclusions: the combination of hydroxyapatite and lysozyme may be an alternative for reducing the S. mutans burden in dentinal caries. PMID:27656068

  7. Comparison of shear bond strength of amalgam bonded to primary and permanent dentin.

    PubMed

    Mahdi, S; Bahman, S; Arghavan, A B; Fatemeh, M

    2008-06-01

    Amalgam's non-adhesive characteristics necessitate cavity preparations incorporating retentive features, which often require the removal of non-carious tooth structure. Use of adhesives beneath amalgam restorations, would be helpful to overcome this disadvantage. This study was undertaken to compare the mean shear bond strength of amalgam bonded to primary and permanent dentin, to evaluate the efficacy of amalgam adhesives in pediatric dentistry.27 primary and 28 permanent posterior teeth with intact buccal or lingual surfaces were grounded to expose dentin and wet-polished with 400-grit silicone carbide paper. Scotchbond Multi Purpose Plus adhesive system was applied to the dentin surfaces and light cured. Amalgam was condensed onto the treated dentin through a plastic mold.shear bond strength testing was done using an Instron Universal testing machine, at a crosshead speed of 0.5 mm/min.The data were analyzed by independent samples t-test The difference among the two groups was not statistically significant (p>0.05) Bonded amalgam showed the same level of bond strength to primary and permanent dentin; so, application of amalgam bonding agents in pediatric dentistry can be recommended.

  8. Effects of Novel 3D Antibiotic-Containing Electrospun Scaffolds on Dentin Discoloration

    PubMed Central

    Porter, Margaret Louise A.; Münchow, Eliseu A.; Albuquerque, Maria T. P.; Spolnik, Kenneth J.; Hara, Anderson T.; Bottino, Marco C.

    2016-01-01

    Introduction Although intracanal application of the triple antibiotic paste (TAP) may offer advantages (e.g., disinfection), this practice has been associated with significant drawbacks, including tooth discoloration. In this study, the color change of dentin was monitored during treatment with distinct TAP pastes and novel tubular-shaped three-dimensional (3D) electrospun scaffolds containing minocycline-MINO or doxycycline-DOX. Methods Two TAP pastes (TAPMINO–MINO, metronidazole/MET, and ciprofloxacin/CIP; and TAPDOX–DOX, MET, and CIP), four scaffold-based groups containing MINO or DOX, at distinct concentrations; one antibiotic-free scaffold (Scaffold); and one untreated group (Control) were investigated. Human canines were sectioned at the cemento-enamel junction (CEJ) and tubular-shaped scaffolds or paste were placed into the root canals and sealed. Color measurements (CIEL*a*b* parameters) were performed at baseline and after 1, 3, 7, 14, 21, and 28 days. Color changes were expressed as ΔE* values. In addition, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were also performed on the specimens after treatment. Data were analyzed using Repeated-measures ANOVA (alpha=0.05). Results All antibiotic-containing groups led to greater discoloration than the antibiotic-free groups. A severe discoloration occurred after 1 day. At the end of the experiment, antibiotic-treated samples exhibited crusts/agglomerates over the dentin surface, which totally or partially obliterated the dentinal tubules. The presence of MINO resulted in greater color change than DOX. Conclusion Scaffolds containing MINO or DOX produced similar color change to dentin when compared to their respective TAP systems, although DOX-related discoloration was less pronounced. PMID:26602451

  9. Tensile bond strength and SEM evaluation of caries-affected dentin using dentin adhesives.

    PubMed

    Nakajima, M; Sano, H; Burrow, M F; Tagami, J; Yoshiyama, M; Ebisu, S; Ciucchi, B; Russell, C M; Pashley, D H

    1995-10-01

    Tensile bond strength measurements are commonly used for the evaluation of dentin adhesive systems. Most tests are performed using extracted non-carious human or bovine dentin. However, the adhesion of resins to caries-affected dentin is still unclear. The objectives of this study were to test the hypothesis that bonding to caries-affected dentin is inferior to bonding to normal dentin, and that the quality of the hybrid layer plays a major role in creating good adhesion. We used a micro-tensile bond strength test to compare test bond strengths made to either caries-affected dentin or normal dentin, using three commercial adhesive systems (All Bond 2, Scotchbond Multi-Purpose, and Clearfil Liner Bond II). For scanning electron microscopy, the polished interfaces between the adhesive bond and dentin were subjected to brief exposure to 10% phosphoric acid solution and 5% sodium hypochlorite, so that the quality of the hybrid layers could be observed. Bonding to normal dentin with either All Bond 2 (26.9 +/- 8.8 MPa) or Clearfil Liner Bond II (29.5 +/- 10.9 MPa) showed tensile bond strengths higher than those to caries-affected dentin (13.0 +/- 3.6 MPa and 14.0 +/- 4.3 MPa, respectively). The tensile bond strengths obtained with Scotchbond Multi-Purpose were similar in normal and caries-affected dentin (20.3 +/- 5.5 MPa and 18.5 +/- 4.0 MPa, respectively). The hybrid layers created by All Bond 2 in normal dentin and by Clearfil Liner Bond II in normal or caries-affected dentin showed phosphoric acid and sodium hypochlorite resistance, whereas the hybrid layers created by All Bond 2 in caries-affected dentin and those created by Scotchbond Multi-Purpose to normal and caries-affected dentin showed partial susceptibility to the acid and sodium hypochlorite treatment. The results indicate that the strength of adhesion to dentin depends upon both the adhesive system used and the type of dentin. Moreover, the quality of the hybrid layer may not always contribute

  10. Dentin bonding: can we make it last?

    PubMed

    Tjäderhane, L

    2015-01-01

    In dentin bonding, contemporary dental adhesive systems rely on formation of the hybrid layer, a biocomposite containing dentin collagen and polymerized resin adhesive. They are usually able to create at least reasonable integrity of the hybrid layer with high immediate bond strength. However, loss of dentin-bonded interface integrity and bond strength is commonly seen after aging both in vitro and in vivo. This is due to endogenous collagenolytic enzymes, matrix metalloproteinases, and cysteine cathepsins, responsible for the time-dependent loss of hybrid layer collagen. In addition, the hydrophilic nature of adhesive systems creates problems that lead to suboptimal hybrid layers. These problems include, for example, insufficient resin impregnation of dentin, phase separation, and a low rate of polymerization, all of which may reduce the longevity of the bonded interface. Preservation of the collagen matrix integrity by inhibition of endogenous dentin proteases is key to improving dentin bonding durability. Several approaches to retain the integrity of the hybrid layer and to improve the long-term dentin bond strength have been tested. These include the use of enzyme inhibitors, either separately or as incorporated into the adhesive resins; increase of collagen resistance to enzymatic degradation; and elimination of water from the interface to slow down or eliminate hydrolytic loss of the hybrid layer components. This review looks at the principles, current status, and future of the different techniques designed to prevent the loss of hybrid layer and bond strength.

  11. Dentine roughness after different surface treatments.

    PubMed

    Mohsen, M M; Shabka, A A

    1993-01-01

    Surface roughness is one of the most influential criteria affecting the durability and strength of the adhesive restorative materials to the dentine. This study was carried out to investigate the roughness of the dentine surface after some of the modalities proposed for its treatment prior to application of the DBA. Dentine surface roughness of the sixty teeth divided into 12 groups were tested where the dentine surfaces were denuded and were brought to a similar 600 grit surface roughness then different treatments were carried out using H2O2, CO2 gas laser at 30 and 48 J/cm2 energy densities, EDTA and polyacrylic acid treatments. The dentine surface roughness was determined using a profilometer and the results were digitized and plotted using an AUTO-CAD software and Rolland plotter to compare the effects of the different treatments on the dentine surface roughness of the tested samples. Results revealed that the laser treatment left smooth dentine surface and added further evidences to the simplicity and reliability of the conventional use of EDTA and the polyacrylic acid according to the type of adhesive to be used.

  12. Comparative evaluation of a dentifrice containing calcium sodium phosphosilicate to a dentifrice containing potassium nitrate for dentinal hypersensitivity: A clinical study

    PubMed Central

    Satyapal, Tanya; Mali, Rohini; Mali, Amita; Patil, Vishakha

    2014-01-01

    Background: Calcium sodium phosphosilicate is a recently introduced desensitizing agent which acts by occluding the dentinal tubules and also resists acid decalcification. This study was designed to assess the efficacy of a new toothpaste containing 5% calcium sodium phosphosilicate for the treatment of dentinal hypersensitivity and also compare it with 5% potassium nitrate. Materials and Methods: Sixty patients with the chief complaint of dentinal hypersensitivity were enrolled and randomly divided into two groups. The visual analog scale (VAS) scores were taken for water and air stimuli at baseline, 3 weeks after usage of the respective toothpaste, and 3 weeks after discontinuation of the respective toothpaste. Results: Both the groups showed reduction in hypersensitivity scores at 3 weeks and 6 weeks for air stimulus and cold water. The calcium sodium phosphosilicate group, however, showed significantly reduction in hypersensitivity compared to the potassium nitrate group at any time point for both measures of hypersensitivity. Conclusion: The 5% calcium sodium phosphosilicate group showed immense reduction in dentinal hypersensitivity symptoms. The 5% calcium sodium phosphosilicate showed prolonged effects even after discontinuation as compared to 5% potassium nitrate, due to its dentinal tubular occlusion property. PMID:25425819

  13. Immune and stress response 'cross-talk' in the Drosophila Malpighian tubule.

    PubMed

    Davies, Shireen-Anne; Overend, Gayle; Sebastian, Sujith; Cundall, Maria; Cabrero, Pablo; Dow, Julian A T; Terhzaz, Selim

    2012-04-01

    The success of insects is in large part due to their ability to survive environmental stress, including heat, cold, and dehydration. Insects are also exposed to infection, osmotic or oxidative stress, and to xenobiotics or toxins. The molecular mechanisms of stress sensing and response have been widely investigated in mammalian cell lines, and the area of stress research is now so vast to be beyond the scope of a single review article. However, the mechanisms by which stress inputs to the organism are sensed and integrated at the tissue and cellular level are less well understood. Increasingly, common molecular events between immune and other stress responses are observed in vivo; and much of this work stems of efforts in insect molecular science and physiology. We describe here the current knowledge in the area of immune and stress signalling and response at the level of the organism, tissue and cell, focussing on a key epithelial tissue in insects, the Malpighian tubule, and drawing together the known pathways that modulate responses to different stress insults. The tubules are critical for insect survival and are increasingly implicated in responses to multiple and distinct stress inputs. Importantly, as tubule function is central to survival, they are potentially key targets for insect control, which will be facilitated by increased understanding of the complexities of stress signalling in the organism.

  14. Optical Spectroscopy Study of Transparent Non-Carious Human Dentin and Dentin-Enamel Junction

    SciTech Connect

    Marshall, G.W.; Marshall, S.J.; Gallagher, R.R.; Demos, S.

    1999-12-14

    Improving our knowledge of the morphology, composition and properties of the dentin, enamel, and the dentin-enamel junction (DEJ) is vital for the development of improved restorative materials and clinical placement techniques. Most studies of dental tissues have used light microscopy for characterization. In our investigation, the spectroscopic properties of normal and non-carious transparent human root dentin, and the dentin-enamel junction were investigated using emission imaging microscopy, and micro-spectroscopy. Experimental results reveal new information on the structural and biochemical characteristics of these dental tissues.

  15. Surface temperature and thermal penetration depth of Nd:YAG laser applied to enamel and dentin

    NASA Astrophysics Data System (ADS)

    White, Joel M.; Neev, Joseph; Goodis, Harold E.; Berns, Michael W.

    1992-06-01

    The determination of the thermal effects of Nd:YAG laser energy on enamel and dentin is critical in understanding the clinical applications of caries removal and surface modification. Recently extracted non-carious third molars were sterilized with gamma irradiation. Calculus and cementum were removed using scaling instruments and 600 grit sand paper. The smear layer produced by sanding was removed with a solution of 0.5 M EDTA (pH 7.4) for two minutes. Enamel and dentin surfaces were exposed to a pulsed Nd:YAG laser with 150 microsecond(s) pulse duration. Laser energy was delivered to the teeth with a 320 micrometers diameter fiberoptic delivery system, for exposure times of 1, 10 and 30 seconds. Laser parameters varied from 0.3 to 3.0 W, 10 to 30 Hz and 30 to 150 mJ/pulse. Other conditions included applications of hot coffee, carbide bur in a dental air-cooled turbine drill and soldering iron. Infrared thermography was used to measure the maximum surface temperature on, and thermal penetration distance into enamel and dentin. Thermographic data were analyzed with a video image processor to determine the diameter of maximum surface temperature and thermal penetration distance of each treatment. Between/within statistical analysis of variance (p dentin in thermal effects from the Nd:YAG laser. Enamel had lower maximum surface temperatures than dentin for all laser powers and times. The surface temperature ranged from 34 +/- 1 degree(s)C to 110 +/- 4 degree(s)C on enamel and 62 +/- 5 degree(s)C to 392 +/- 82 degree(s)C on dentin. As power and time of exposure increased, both the maximum surface temperature and thermal penetration distance increased. The greatest length of thermal effect on the surface (11.0 +/- 0.9 mm) and thermal penetration distance (4.7 +/- 0.4 mm) recorded were caused by the air-cooled turbine drill on dentin. Surface temperatures were much higher for the Nd:YAG laser applied to enamel

  16. Regulation of glomerulotubular balance: flow-activated proximal tubule function.

    PubMed

    Wang, Tong; Weinbaum, Sheldon; Weinstein, Alan M

    2017-03-07

    The purpose of this review is to summarize our knowledge and understanding of the physiological importance and the mechanisms underlying flow-activated proximal tubule transport. Since the earliest micropuncture studies of mammalian proximal tubule, it has been recognized that tubular flow is an important regulator of sodium, potassium, and acid-base transport in the kidney. Increased fluid flow stimulates Na(+) and HCO3(-) absorption in the proximal tubule via stimulation of Na/H-exchanger isoform 3 (NHE3) and H(+)-ATPase. In the proximal tubule, brush border microvilli are the major flow sensors, which experience changes in hydrodynamic drag and bending moment as luminal flow velocity changes and which transmit the force of altered flow to cytoskeletal structures within the cell. The signal to NHE3 depends upon the integrity of the actin cytoskeleton; the signal to the H(+)-ATPase depends upon microtubules. We have demonstrated that alterations in fluid drag impact tubule function by modulating ion transporter availability within the brush border membrane of the proximal tubule. Beyond that, there is evidence that transporter activity within the peritubular membrane is also modulated by luminal flow. Secondary messengers that regulate the flow-mediated tubule function have also been delineated. Dopamine blunts the responsiveness of proximal tubule transporters to changes in luminal flow velocity, while a DA1 antagonist increases flow sensitivity of solute reabsorption. IP3 receptor-mediated intracellular Ca(2+) signaling is critical to transduction of microvillus drag. In this review, we summarize our findings of the regulatory mechanism of flow-mediated Na(+) and HCO3(-) transport in the proximal tubule and review available information about flow sensing and regulatory mechanism of glomerulotubular balance.

  17. Water distribution in dentin matrices: bound vs. unbound water

    PubMed Central

    Agee, Kelli A.; Prakki, Anuradha; Abu-Haimed, Tariq; Naguib, Ghada H.; Nawareg, Manar Abu; Tezvergil-Mutluay, Arzu; Scheffel, Debora L.S.; Chen, Chen; Jang, Seung Soon; Hwang, Hyea; Brackett, Martha; Grégoire, Geneviéve; Tay, Franklin R.; Breschi, Lorenzo; Pashley, David H.

    2015-01-01

    Objectives This work measured the amount of bound versus unbound water in completely-demineralized dentin. Methods Dentin beams prepared from extracted human teeth were completely demineralized, rinsed and dried to constant mass. They were rehydrated in 41% relative humidity (RH), while gravimetrically measuring their mass increase until the first plateau was reached at 0.064 (vacuum) or 0.116 g H2O/g dry mass (Drierite). The specimens were then exposed to 60% RH until attaining the second plateau at 0.220 (vacuum) or 0.191 g H2O/g dry mass (Drierite), and subsequently exposed to 99% RH until attaining the third plateau at 0.493 (vacuum) or 0.401 g H2O/g dry mass (Drierite). Results Exposure of the first layer of bound water to 0% RH for 5 min produced a −0.3% loss of bound water; in the second layer of bound water it caused a −3.3% loss of bound water; in the third layer it caused a −6% loss of bound water. Immersion in 100% ethanol or acetone for 5 min produced a 2.8 and 1.9% loss of bound water from the first layer, respectively; it caused a −4 and −7% loss of bound water in the second layer, respectively; and a −17 and −23% loss of bound water in the third layer.. Bound water represented 21–25% of total dentin water. Chemical dehydration of water-saturated dentin with ethanol/acetone for 1 min only removed between 25 to 35% of unbound water, respectively. Significance Attempts to remove bound water by evaporation were not very successful. Chemical dehydration with 100% acetone was more successful than 100% ethanol especially the third layer of bound water. Since unbound water represents between 75–79% of total matrix water, the more such water can be removed, the more resin can be infiltrated. PMID:25612786

  18. Reduced tolerance of immature renal tubules to anoxia by HSF-1 decoy.

    PubMed

    Sreedharan, Rajasree; Riordan, Michael; Wang, Shirley; Thulin, Gunilla; Kashgarian, Michael; Siegel, Norman J

    2005-02-01

    Immature animals demonstrate an amplified heat shock response following a variety of insults compared with that seen in mature animals (M). The potential role of the heat shock response in modulating immature tolerance to injury was compared between rat pups, 10 postnatal days of age (P10), and M. Baseline levels of the heat shock transcription factor (HSF-1) were substantially elevated in P10 compared with M animals. In uninjured P10 pups, HSF-1 level was comparable to that of M animals subjected to 45 min of ischemia. As anticipated, the integrity of suspensions of tubules exposed to anoxia was preserved in P10 animals (23% LDH release) compared with M (40%), P < 0.01. The effect of targeted inhibition of HSF-1 on tubular integrity was studied using a cyclic oligonucleotide decoy. The HSF-1 decoy increased the severity of anoxic injury in P10 pups to a level comparable with M animals. LDH release was 33% in decoy-treated P10 tubules compared with 40% in M. When P10 tubules were treated with scrambled decoy, resistance to anoxia remained intact (24%). The increased vulnerability of the tubular suspension to injury was specific to the HSF-1 decoy and proportional to the dose of decoy applied. This study demonstrates maturation in the abundance of HSF-1 in the immature rat kidney. The loss of resistance of immature tubules to anoxia with specific inhibition of HSF-1 may be due to its effect on the heat shock response or other signaling pathways of critical pathobiological importance in renal cell injury.

  19. The Proximal Tubule and Albuminuria: Really!

    PubMed Central

    Dickson, Landon E.; Wagner, Mark C.; Sandoval, Ruben M.

    2014-01-01

    Recent data highlight the role of the proximal tubule (PT) in reabsorbing, processing, and transcytosing urinary albumin from the glomerular filtrate. Innovative techniques and approaches have provided exciting insights into these processes, and numerous investigators have shown that selective PT cell defects lead to significant albuminuria, even reaching nephrotic range in animal models. Thus, the mechanisms of albumin reabsorption and transcytosis are undergoing intense study. Working in concert with megalin and cubilin, a nonselective multireceptor complex that predominantly directs proteins for lysosomal degradation, the neonatal Fc receptor (FcRn) located at the brush border of the apical membrane has been implicated as the “receptor” mediating albumin transcytosis. The FcRn pathway facilitates reabsorption and mediates transcytosis by its pH-dependent binding affinity in endosomal compartments. This also allows for selective albumin sorting within the PT cell. This reclamation pathway minimizes urinary losses and catabolism of albumin, thus prolonging its serum half-life. It may also serve as a molecular sorter to preserve and reclaim normal albumin while allowing “altered” albumin to be catabolized via lysosomal pathways. Here, we critically review the data supporting this novel mechanism. PMID:24408874

  20. Acemannan, an extracted product from Aloe vera, stimulates dental pulp cell proliferation, differentiation, mineralization, and dentin formation.

    PubMed

    Jittapiromsak, Nawaporn; Sahawat, Dusida; Banlunara, Wijit; Sangvanich, Polkit; Thunyakitpisal, Pasutha

    2010-06-01

    This study investigated the effect of acemannan (Aloe vera gel polysaccharide) on dentin formation. Primary human dental pulp cells were treated with acemannan. New DNA synthesis, bone morphogenetic protein-2, alkaline phosphatase activity, dentin sialoprotein expression, and mineralization were determined by [(3)H]-thymidine incorporation, enzyme-linked immunosorbent assay, biochemical assay, western blotting, and Alizarin Red staining, respectively. Then the upper first molars of 24 male Sprague Dawley rats were intentionally exposed and capped with either acemannan or calcium hydroxide. At day 28, the teeth were histopathologically examined and evaluated for the degree of inflammation, dentin bridge formation, and pulp tissue organization. The results revealed that acemannan significantly increased pulp cell proliferation, bone morphogenetic protein-2, alkaline phosphatase activity, dentin sialoprotein expression, and mineralization, compared with the untreated group. The acemannan-treated group also exhibited a complete homogeneous calcified dentin bridge and good pulp tissue organization, whereas neither was detected in the calcium hydroxide-treated and sham groups. In the acemannan-treated group, either mild or no inflammation was found, whereas the other groups had various degrees of inflammation. The data suggest that acemannan promotes dentin formation by stimulating primary human dental pulp cell proliferation, differentiation, extracellular matrix formation, and mineralization. Acemannan also has pulpal biocompatibility and promotes soft tissue organization.

  1. MMP Inhibitors on Dentin Stability

    PubMed Central

    Montagner, A.F.; Sarkis-Onofre, R.; Pereira-Cenci, T.; Cenci, M.S.

    2014-01-01

    The aim of this study was to systematically review the literature for in vitro and ex vivo studies that evaluated the effect of matrix metalloproteinase (MMP) inhibitors during the adhesive procedure on the immediate and long-term resin-dentin bond strength. The search was conducted in 6 databases with no publication year or language limits, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. From 1,336 potentially eligible studies, 48 were selected for full-text analysis, and 30 were included for review, with 17 considered in the meta-analysis. Two reviewers independently selected the studies, extracted the data, and assessed the risk of bias. Pooled effect estimates were expressed as the weighted mean difference between groups. The most used MMP inhibitor was chlorhexidine (CHX). Immediate bond strength results showed no difference between 2% CHX and control; however, a difference was found between 0.2% CHX and control at baseline. After aging, CHX presented higher bond strength values compared to control groups (p < .05). However, this was not observed for longer periods of aging. High heterogeneity was found in some comparisons, especially for the water storage aging subgroup. Subgroup analyses showed that self-etching and etch-and-rinse adhesives are benefited by the CHX use. From the studies included, only 1 presented low risk of bias, while the others showed medium or high risk of bias. The use of MMP inhibitors did not affect the immediate bond strength overall, while it influenced the aged bond strength. Aging procedures influenced bond strength values of the dentin adhesion stability. PMID:24935066

  2. Effect of acidic solutions on the microhardness of dentin and set OrthoMTA and their cytotoxicity on murine macrophage

    PubMed Central

    Shon, Won-Jun; Lee, Woocheol

    2016-01-01

    Objectives To evaluate the effects of three acids on the microhardness of set mineral trioxide aggregate (MTA) and root dentin, and cytotoxicity on murine macrophage. Materials and Methods OrthoMTA (BioMTA) was mixed and packed into the human root dentin blocks of 1.5 mm diameter and 5 mm height. Four groups, each of ten roots, were exposed to 10% citric acid (CA), 5% glycolic acid (GA), 17% ethylenediaminetetraacetic acid (EDTA), and saline for five minutes after setting of the OrthoMTA. Vickers surface microhardness of set MTA and dentin was measured before and after exposure to solutions, and compared between groups using one-way ANOVA with Tukey test. The microhardness value of each group was analyzed using student t test. Acid-treated OrthoMTA and dentin was examined by scanning electron microscope (SEM). Cell viability of tested solutions was assessed using WST-8 assay and murine macrophage. Results Three test solutions reduced microhardness of dentin. 17% EDTA demonstrated severe dentinal erosion, significantly reduced the dentinal microhardness compared to 10% CA (p = 0.034) or 5% GA (p = 0.006). 10% CA or 5% GA significantly reduced the surface microhardness of set MTA compared to 17% EDTA and saline (p < 0.001). Acid-treated OrthoMTA demonstrated microporous structure with destruction of globular crystal. EDTA exhibited significantly more cellular toxicity than the other acidic solutions at diluted concentrations (0.2, 0.5, 1.0%). Conclusions Tested acidic solutions reduced microhardness of root dentin. Five minute's application of 10% CA and 5% GA significantly reduced the microhardness of set OrthoMTA with lower cellular cytotoxicity compared to 17% EDTA. PMID:26877986

  3. Substantivity of Chlorhexidine to Human Dentin

    PubMed Central

    Carrilho, Marcela R.; Carvalho, Ricardo M.; Sousa, Ethan N.; Nicolau, José; Breschi, Lorenzo; Mazzoni, Annalisa; Tjäderhane, Leo; Tay, Franklin R.; Agee, Kelli; Pashley, David H.

    2010-01-01

    Objectives To better comprehend the role of CHX in the preservation of resin-dentin bonds, this study investigated the substantivity of CHX to human dentin. Material and Methods Dentin disks (n= 45) were obtained from the mid-coronal portion of human third molars. One-third of dentin disks were kept mineralized (MD), while the other two-thirds had one of the surfaces partially demineralized with 37% phosphoric acid for 15 s (PDD) or they were totally demineralized with 10% phosphoric acid (TDD). Disks of hydroxyapatite (HA) were also prepared. Specimens were treated with: 1) 10 μL of distilled water (controls), 2) 10 μL of 0.2% chlorhexidine diacetate (0.2% CHX) or 3) 10 μL of 2% chlorhexidine diacetate (2% CHX). Then, they were incubated in 1 mL of PBS (pH 7.4, 37 °C). Substantivity was evaluated as a function of the CHX-applied dose after: 0.5h, 1h, 3h, 6h, 24h, 168h (1wk), 672h (4wks) and 1344h (8wks) of incubation. CHX concentration in eluates was spectrophotometrically analyzed at 260 nm. Results Significant amounts of CHX remained retained in dentin substrates (MD, PPD or TDD), independent on the CHX-applied dose or time of incubation (p<0.05). High amounts of retained CHX onto HA were observed only for specimens treated with the highest concentration of CHX (2%) (p<0.05). Conclusion The outstanding substantivity of CHX to dentin and its reported effect on the inhibition of dentinal proteases may explain why CHX can prolong the durability of resin-dentin bonds. PMID:20472282

  4. Physical, chemical, and histologic changes in dentin caries lesions of primary teeth induced by regular use of polyol chewing gums.

    PubMed

    Mäkinen, K K; Chiego, D J; Allen, P; Bennett, C; Isotupa, K P; Tiekso, J; Mäkinen, P L

    1998-06-01

    A previous clinical trial showed that long-term use of saliva-stimulating polyol (xylitol and sorbitol) chewing gums was associated with arrest of dental caries in young subjects. After a 20-22-month intervention (when the subjects were 8 years old), a total of 23 primary teeth with extensive dentin caries lesions whose surface in clinical examination was found to be totally rehardened (remineralized) could be removed because the teeth were near their physiologic exfoliation time. These teeth were subjected to histologic, microhardness, and electron microscopic tests. The majority of the specimens had been remineralized from the surface by a non-cellular-mediated process within the remaining collapsed, organic extracellular matrix associated with the remaining dentinal surface. Many of the underlying dentinal tubules were filled with a matrix that had been subsequently mineralized. Dental microanalyses showed that the topmost (outer) 20-microm-thick rehardened layer of the lesions exhibited the highest Ca:P ratio, which leveled off at a depth of approximately 150 microm. The rehardened surface layer (normally <0.1 mm in thickness) was significantly (P < 0.001) harder than sound dentin and nearly as hard as sound enamel. Although the main source of the mineral present in the rehardened layer was most likely of salivary origin, some extracellular remineralization was probably mediated by odontoblasts. The results complete the dinical diagnoses of the original trial and suggest that regular use of polyol chewing gums may induce changes in dentin caries lesions, which in histologic and physiochemical studies show typical characteristics of rehardening and mineralization.

  5. Permeability of normal versus carious dentin.

    PubMed

    Pashley, E L; Talman, R; Horner, J A; Pashley, D H

    1991-10-01

    Although a number of reports have been published demonstrating that carious dentin is less permeable than normal dentin, these reports have been qualitative rather than quantitative. The purpose of this in vitro study was to apply a quantitative technique to the study of the permeability of carious human teeth before and after excavation, before and after removal of the smear layer and before and after preparation of a control cavity of similar size and depth in normal dentin subjected to the same measurements, for comparative purposes. Dentin permeability was measured as a hydraulic conductance. The permeability values measured at each step in the protocol were expressed as a percent of the maximum permeability of both cavities, permitting each tooth the serve as its own control. Carious lesions exhibited a slight degree of permeability (2.3 +/- 0.6% of controls) which remained unchanged after excavation of the lesions. Removal of the smear layer in the excavated carious lesions increased the permeability significantly to 6.9 +/- 3.2%. Preparation of a control cavity of the same area and depth increased the permeability slightly. Removal of its smear layer increased the permeability of the dentin 91%. These results confirm previous qualitative studies that carious dentin, even after excavation and removal of the smear layer has a very low permeability.

  6. Remineralization of caries lesions extending into dentin.

    PubMed

    ten Cate, J M

    2001-05-01

    Remineralization is one aspect of the overall process of tooth decay. However, it is primarily studied in shallow lesions. The aim of this study was to explore whether caries lesions in enamel and extending into the dentin can be remineralized. A single-section model was developed for the longitudinal and non-destructive monitoring of changes in enamel and dentin. Lesions at least 200 microm into dentin were formed in undersaturated acetate buffers. Next, the lesions were divided into groups (three treatment and one control) and remineralized. The treatments were: weekly immersion in 1,000 ppm fluoride, single treatment with methanehydroxybisphosphonate, and a constant level of 1 ppm fluoride. De- and remineralization was assessed by transverse microradiography. Remineralization was observed in enamel, but also in dentin, indicating that, deep into dentin, the pores become supersaturated to apatite formation. Treatments affected remineralization only in the outer part of enamel. Both findings are explained by a relatively fast diffusion of mineral ions, with precipitation being rate-limiting. The results suggest that dentin remineralization, underneath enamel, can be achieved and could possibly be used in clinical treatment strategies.

  7. Shear bond strength of composite resin to dentin after application of cavity disinfectants – SEM study

    PubMed Central

    Sharma, Vivek; Rampal, Poonam; Kumar, Sukesh

    2011-01-01

    Aim: The aim was to evaluate the effect of different cavity disinfectants on dentin bond strengths of composite resin applied with two different adhesive systems. Materials and Methods: Two-hundred mandibular molars were sectioned parallel to the occlusal surface to expose dentin in the midcoronal one-third. The dentinal surfaces were polished with waterproof-polishing papers. The specimens were randomly divided into five groups of 40 teeth each as follows: group 1(control) -- specimens were not treated with any cavity disinfectants. Groups 2--5 (experimental groups) -- dentin surfaces were treated with the following cavity disinfectants, respectively; 2% chlorhexidine solution, 0.1% benzalkonium chloride-based disinfectant, 1% chlorhexidine gel, and an iodine potassium iodide/copper sulfate-based disinfectant. The specimens were then randomly divided into two subgroups including 20 teeth each to evaluate the effect of different bonding systems. Dentin bonding systems were applied to the dentin surfaces and the composite buildups were done. After the specimens were stored in an incubator for 24 hours, the shear bond strength was measured at a crosshead speed of 1 mm/min. The specimens were then statistically analyzed. Statistical Analysis Used: One way analysis of variance and Tukey-HSD tests were used. Results: There was no significant difference between chlorhexidine gel and control groups regardless of the type of the bonding agent used (P>0.05). On the other hand, pretreatment with benzalkonium chloride-based, iodine potassium iodide/copper sulfate-based disinfectants or chlorhexidine solutions had a negative effect on the shear bond strength of self-etching bonding systems. Conclusions: The findings of this study suggest that when benzalkonium chloride-based, iodine potassium iodide/copper sulfate-based disinfectants or chlorhexidine solutions are used as a cavity disinfectant, an etch-and-rinse bonding system should be preferred. PMID:22090756

  8. Root canal hydrophobization by dentinal silanization: improvement of silicon-based endodontic treatment tightness.

    PubMed

    Collart Dutilleul, Pierre-Yves; Fonseca, Cesar Gaitán; Zimányi, László; Romieu, Olivier; Pozos-Guillén, Amaury J; Semetey, Vincent; Cuisinier, Frédéric; Pérez, Elías; Levallois, Bernard

    2013-07-01

    A new strategy to improve silicon-based endodontic treatment tightness by dentine hydrophobization is presented in this work: root dentine was silanized to obtain a hydrophobic dentine-sealer interface that limits fluid penetration. This strategy was based on the grafting of aliphatic carbon chains on the dentine through a silanization with the silane end groups [octadecyltrichlorosilane (OTS) and octadecyltriethoxysilane]. Dentine surface was previously pretreated, applying ethylenediaminetetraacetic acid and sodium hypochlorite, to expose hydroxyl groups of collagen for the silane grafting. Collagen fibers exposure after pretreatment was visible with scanning electron microscopy, and Fourier transform infrared (FTIR) spectroscopy showed their correct exposition for the silanization (amide I and II, with 1630, 1580, and 1538 cm⁻¹ peaks corresponding to the vibration of C=O and C--N bonds). The grafting of aliphatic carbon chains was confirmed by FTIR (peaks at 2952 and 2923 cm⁻¹ corresponding to the stretching of C--H bonds) and by the increasing of the water contact angle. The most efficient hydrophobization was obtained with OTS in ethyl acetate, with a water contact angle turning from 51° to 109°. Gas and liquid permeability tests showed an increased seal tightness after silanization: the mean gas and water flows dropped from 2.02 × 10⁻⁸ to 1.62 × 10⁻⁸ mol s⁻¹ and from 10.8 × 10⁻³ to 5.4 × 10⁻³ µL min⁻¹, respectively. These results show clear evidences to turn hydrophilic dentine surface into a hydrophobic surface that may improve endodontic sealing.

  9. Preventive effects of different protective agents on dentin erosion: An in vitro investigation

    PubMed Central

    Gulino, Chiara; Mirando, Maria; Colombo, Marco; Pietrocola, Giampiero

    2017-01-01

    Background The purpose of this in vitro study was to evaluate the preventive effects of different protective agents on dentine erosion, measuring mean percentage weight loss. Dissolution of dentine under erosive challenges caused by soft drinks was analyzed: specimens were weighed following each immersion period, with mean percent weight losses calculated. Material and Methods Extracted teeth were sectioned into uniform slabs. Seventy permanent enamel specimens were randomly distributed to seven groups. Initial weights of all dentin specimens were performed. The fluoride pastes Remin Pro, MI Paste Plus, Tooth Mousse, Biorepair, Biorepair Plus and Regenerate were used in this study. A control group was treated just with tap water. The specimens then were immersed in Coca-Cola for a total of 32 min at room temperature. Finally each specimen was dry and weighed. The mass loss was calculated as a percentage of that observed prior the fluoride pastes application. Weight loss data were subjected to Analysis of Variance (One-way ANOVA) followed by Bonferroni’s post hoc tests. Results Percent weight loss of specimens exposed to early stages in Coca-Cola showed linear progression with time. Specimen’s application of fluoridated varnishes such as Biorepair or Regenerate, prior immersion in Coca-Cola, significantly protect dentin from demineralization. Otherwise, application of Tooth Mousse or Biorepair Plus increased dentin demineralization starting from 24 min of immersion in Coca-Cola. Conclusions Despite the limitations of this study, the protective pastes that showed the less weight loss due to the acidic challenge are Biorepair and Regenerate. Key words:Dentine, erosion, protective agents, soft drinks, toothpastes. PMID:28149456

  10. Heterogeneity of T-Tubules in Pig Hearts

    PubMed Central

    Gadeberg, Hanne C.; Bond, Richard C.; Kong, Cherrie H. T.; Chanoit, Guillaume P.; Ascione, Raimondo; Cannell, Mark B.; James, Andrew F.

    2016-01-01

    Background T-tubules are invaginations of the sarcolemma that play a key role in excitation-contraction coupling in mammalian cardiac myocytes. Although t-tubules were generally considered to be effectively absent in atrial myocytes, recent studies on atrial cells from larger mammals suggest that t-tubules may be more numerous than previously supposed. However, the degree of heterogeneity between cardiomyocytes in the extent of the t-tubule network remains unclear. The aim of the present study was to investigate the t-tubule network of pig atrial myocytes in comparison with ventricular tissue. Methods Cardiac tissue was obtained from young female Landrace White pigs (45–75 kg, 5–6 months old). Cardiomyocytes were isolated by arterial perfusion with a collagenase-containing solution. Ca2+ transients were examined in field-stimulated isolated cells loaded with fluo-4-AM. Membranes of isolated cells were visualized using di-8-ANEPPS. T-tubules were visualized in fixed-frozen tissue sections stained with Alexa-Fluor 488-conjugated WGA. Binary images were obtained by application of a threshold and t-tubule density (TTD) calculated. A distance mapping approach was used to calculate half-distance to nearest t-tubule (HDTT). Results & Conclusion The spatio-temporal properties of the Ca2+ transient appeared to be consistent with the absence of functional t-tubules in isolated atrial myocytes. However, t-tubules could be identified in a sub-population of atrial cells in frozen sections. While all ventricular myocytes had TTD >3% (mean TTD = 6.94±0.395%, n = 24), this was true of just 5/22 atrial cells. Mean atrial TTD (2.35±0.457%, n = 22) was lower than ventricular TTD (P<0.0001). TTD correlated with cell-width (r = 0.7756, n = 46, P<0.0001). HDTT was significantly greater in the atrial cells with TTD ≤3% (2.29±0.16 μm, n = 17) than in either ventricular cells (1.33±0.05 μm, n = 24, P<0.0001) or in atrial cells with TTD >3% (1.65±0.06 μm, n = 5, P<0.05). These

  11. From single molecule to single tubules

    NASA Astrophysics Data System (ADS)

    Guo, Chin-Lin

    2012-02-01

    Biological systems often make decisions upon conformational changes and assembly of single molecules. In vivo, epithelial cells (such as the mammary gland cells) can respond to extracellular matrix (ECM) molecules, type I collagen (COL), and switch their morphology from a lobular lumen (100-200 micron) to a tubular lumen (1mm-1cm). However, how cells make such a morphogenetic decision through interactions with each other and with COL is unclear. Using a temporal control of cell-ECM interaction, we find that epithelial cells, in response to a fine-tuned percentage of type I collagen (COL) in ECM, develop various linear patterns. Remarkably, these patterns allow cells to self-assemble into a tubule of length ˜ 1cm and diameter ˜ 400 micron in the liquid phase (i.e., scaffold-free conditions). In contrast with conventional thought, the linear patterns arise through bi-directional transmission of traction force, but not through diffusible biochemical factors secreted by cells. In turn, the transmission of force evokes a long-range (˜ 600 micron) intercellular mechanical interaction. A feedback effect is encountered when the mechanical interaction modifies cell positioning and COL alignment. Micro-patterning experiments further reveal that such a feedback is a novel cell-number-dependent, rich-get-richer process, which allows cells to integrate mechanical interactions into long-range (> 1mm) linear coordination. Our results suggest a mechanism cells can use to form and coordinate long-range tubular patterns, independent of those controlled by diffusible biochemical factors, and provide a new strategy to engineer/regenerate epithelial organs using scaffold-free self-assembly methods.

  12. Is bovine dentine an appropriate substitute for human dentine in erosion/abrasion tests?

    PubMed

    Wegehaupt, F; Gries, D; Wiegand, A; Attin, T

    2008-05-01

    The study aimed to compare the dentine wear of primary and permanent human and bovine teeth because of erosion/abrasion and evaluate if bovine dentine is an appropriate substitute for human dentine in further erosion/abrasions tests. Dentine samples from deciduous molars and human third molars as well as from calves' and cattle's lower incisors were prepared and baseline surface profiles were recorded. Each day all samples were demineralized in 1% citric acid, tooth brushed with 100 brushing strokes with toothpaste slurry and stored in artificial saliva for the rest of the day. This cycle was run for 20 days. Afterwards, new surface profiles were recorded and dentine wear was calculated by a customized computer program. Dentine wear because of erosion/abrasion was not statistically, significantly different for human third molars and cattle's lower incisors (P = 0.7002). The dentine wear because of erosion/abrasion of deciduous molars and calves' lower incisors was significantly different (P < 0.0000). No statistically significant difference in the dentine wear of human third molars and cattle's lower incisors was observed, so that the use of cattle's lower incisors as substitute for adult human teeth for further investigations in erosion/abrasion studies could be accepted.

  13. An Automated Image Analysis System to Quantify Endosomal Tubulation

    PubMed Central

    Newton, Timothy M.

    2016-01-01

    Recycling of cargos from early endosomes requires regulation of endosomal tubule formation and fission. This regulation is disrupted in cells depleted of the microtubule severing enzyme spastin, causing elongation of endosomal tubules and mis-trafficking of recycling endosomal cargos such as the transferrin receptor. Spastin is encoded by SPAST, mutations in which are the most frequent cause of autosomal dominant hereditary spastic paraplegia, a condition characterised by a progressive loss of lower limb function resulting from upper motor neuron axonopathy. Investigation of molecular factors involved in endosomal tubule regulation is hindered by the need for manual counting of endosomal tubules. We report here the development of an open source automated system for the quantification of endosomal tubules, using ImageJ and R. We validate the method in cells depleted of spastin and its binding partner IST1. The additional speed and reproducibility of this system compared with manual counting makes feasible screens of candidates to further understand the mechanisms of endosomal tubule formation and fission. PMID:28006827

  14. Structure of Lipid Tubules Formed from a Polymerizable Lecithin

    PubMed Central

    Yager, Paul; Schoen, Paul E.; Davies, Carol; Price, Ronald; Singh, Alok

    1985-01-01

    We have studied tubules formed from a polymerizable lipid in aqueous dispersion using freeze-fracture replication and transmission electron microscopy. The polymerizable diacetylenic lecithin 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine converts from liposomes to hollow cylinders, which we call tubules, on cooling through its chain melting phase transition temperature. These tubules differ substantially from cochleate cylinders formed by phosphatidylserines on binding of calcium. The tubules have diameters that range from 0.3 to 1 μm and lengths of up to hundreds of micrometers depending on conditions of formation. The thickness of the walls varies from as few as two bilayers to tens of bilayers in some longer tubules. Their surfaces may be either smooth, gently rippled, or with spiral steps depending on sample preparation conditions, including whether the lipids have been polymerized. The spiral steps may reflect the growth of the tubules by rolling up of flattened liposomes. ImagesFIGURE 1FIGURE 2FIGURE 3FIGURE 4FIGURE 5FIGURE 6FIGURE 7FIGURE 8FIGURE 9 PMID:19431600

  15. Function-informed transcriptome analysis of Drosophila renal tubule

    PubMed Central

    Wang, Jing; Kean, Laura; Yang, Jingli; Allan, Adrian K; Davies, Shireen A; Herzyk, Pawel; Dow, Julian AT

    2004-01-01

    Background Comprehensive, tissue-specific, microarray analysis is a potent tool for the identification of tightly defined expression patterns that might be missed in whole-organism scans. We applied such an analysis to Drosophila melanogaster Malpighian (renal) tubule, a defined differentiated tissue. Results The transcriptome of the D. melanogaster Malpighian tubule is highly reproducible and significantly different from that obtained from whole-organism arrays. More than 200 genes are more than 10-fold enriched and over 1,000 are significantly enriched. Of the top 200 genes, only 18 have previously been named, and only 45% have even estimates of function. In addition, 30 transcription factors, not previously implicated in tubule development, are shown to be enriched in adult tubule, and their expression patterns respect precisely the domains and cell types previously identified by enhancer trapping. Of Drosophila genes with close human disease homologs, 50 are enriched threefold or more, and eight enriched 10-fold or more, in tubule. Intriguingly, several of these diseases have human renal phenotypes, implying close conservation of renal function across 400 million years of divergent evolution. Conclusions From those genes that are identifiable, a radically new view of the function of the tubule, emphasizing solute transport rather than fluid secretion, can be obtained. The results illustrate the phenotype gap: historically, the effort expended on a model organism has tended to concentrate on a relatively small set of processes, rather than on the spread of genes in the genome. PMID:15345053

  16. The effect of dentin desensitizers and Nd:YAG laser pre-treatment on microtensile bond strength of self-adhesive resin cement to dentin

    PubMed Central

    Tuncer, Duygu; Yuzugullu, Bulem; Celik, Cigdem

    2014-01-01

    PURPOSE The purpose of this study is to evaluate if pre-treatment with desensitizers have a negative effect on microtensile bond strength before cementing a restoration using recently introduced self-adhesive resin cement to dentin. MATERIALS AND METHODS Thirty-five human molars' occlusal surfaces were ground to expose dentin; and were randomly grouped as (n=5); 1) Gluma-(Glutaraldehyde/HEMA) 2) Aqua-Prep F-(Fluoride), 3) Bisblock-(Oxalate), 4) Cervitec Plus-(Clorhexidine), 5) Smart protect-(Triclosan), 6) Nd:YAG laser, 7) No treatment (control). After applying the selected agent, RelyX U200 self-adhesive resin cement was used to bond composite resin blocks to dentin. All groups were subjected to thermocycling for 1000 cycles between 5-55℃. Each bonded specimen was sectioned to microbars (6 mm × 1 mm × 1 mm) (n=20). Specimens were submitted to microtensile bond strength test at a crosshead speed of 0.5 mm/min. Kolmogorov-Smirnov, Levene's test, Kruskal-Wallis One-way Analysis of Variance, and Conover's nonparametric statistical analysis were used (P<.05). RESULTS Gluma, Smart Protect and Nd:YAG laser treatments showed comparable microtensile bond strengths compared with the control group (P>.05). The microtensile bond strengths of Aqua-Prep F, and Cervitec Plus were similar to each other but significantly lower than the control group (P<.05). Bisblock showed the lowest microtensile bond strength among all groups (P<.001). Most groups showed adhesive failure. CONCLUSION Within the limitation of this study, it is not recommended to use Aqua-prep F, Cervitec Plus and Bisblock on dentin when used with a self-adhesive resin cement due to the decrease they cause in bond strength. Beside, pre-treatment of dentin with Gluma, Smart protect, and Nd:YAG laser do not have a negative effect. PMID:24843392

  17. Regulation of reactionary dentin formation by odontoblasts in response to polymicrobial invasion of dentin matrix

    PubMed Central

    Charadram, Nattida; Farahani, Ramin M; Harty, Derek; Rathsam, Catherine; Swain, Michael V; Hunter, Neil

    2011-01-01

    Odontoblast synthesis of dentin proceeds through discrete but overlapping phases characterized by formation of a patterned organic matrix followed by remodelling and active mineralization. Microbial invasion of dentin in caries triggers an adaptive response by odontoblasts, culminating in formation of a structurally altered reactionary dentin, marked by biochemical and architectonic modifications including diminished tubularity. Scanning electron microscopy of the collagen framework in reactionary dentin revealed a radically modified yet highly organized meshwork as indicated by fractal and lacunarity analyses. Immuno-gold labelling demonstrated increased density and regular spatial distribution of dentin sialoprotein (DSP) in reactionary dentin. DSP contributes putative hydroxyapatite nucleation sites on the collagen scaffold. To further dissect the formation of this altered dentin matrix, the associated enzymatic machinery was investigated. Analysis of extracted dentin matrix indicated increased activity of matrix metalloproteinase-2 (MMP-2) in the reactionary zone referenced to physiologic dentin. Likewise, gene expression analysis of micro-dissected odontoblast layer revealed up-regulation of MMP-2. Parallel up-regulation of tissue inhibitor of metalloproteinase-2 (TIMP-2) and membrane type 1- matrix metalloproteinase (MT1-MMP) was observed in response to caries. Next, modulation of odontoblastic dentinogenic enzyme repertoire was addressed. In the odontoblast layer expression of Toll-like receptors was markedly altered in response to bacterial invasion. In carious teeth TLR-2 and the gene encoding the corresponding adaptor protein MyD88 were down-regulated whereas genes encoding TLR-4 and adaptor proteins TRAM and Mal/TIRAP were up-regulated. TLR-4 signalling mediated by binding of bacterial products has been linked to up-regulation of MMP-2. Further, increased expression of genes encoding components of the TGF-β signalling pathway, namely SMAD-2 and SMAD-4

  18. Temporary zinc oxide-eugenol cement: eugenol quantity in dentin and bond strength of resin composite.

    PubMed

    Koch, Tamara; Peutzfeldt, Anne; Malinovskii, Vladimir; Flury, Simon; Häner, Robert; Lussi, Adrian

    2013-08-01

    Uptake of eugenol from eugenol-containing temporary materials may reduce the adhesion of subsequent resin-based restorations. This study investigated the effect of duration of exposure to zinc oxide-eugenol (ZOE) cement on the quantity of eugenol retained in dentin and on the microtensile bond strength (μTBS) of the resin composite. The ZOE cement (IRM Caps) was applied onto the dentin of human molars (21 per group) for 1, 7, or 28 d. One half of each molar was used to determine the quantity of eugenol (by spectrofluorimetry) and the other half was used for μTBS testing. The ZOE-exposed dentin was treated with either OptiBond FL using phosphoric acid (H₃PO₄) or with Gluma Classic using ethylenediaminetetraacetic acid (EDTA) conditioning. One group without conditioning (for eugenol quantity) and two groups not exposed to ZOE (for eugenol quantity and μTBS testing) served as controls. The quantity of eugenol ranged between 0.33 and 2.9 nmol mg⁻¹ of dentin (median values). No effect of the duration of exposure to ZOE was found. Conditioning with H₃PO₄ or EDTA significantly reduced the quantity of eugenol in dentin. Nevertheless, for OptiBond FL, exposure to ZOE significantly decreased the μTBS, regardless of the duration of exposure. For Gluma Classic, the μTBS decreased after exposure to ZOE for 7 and 28 d. OptiBond FL yielded a significantly higher μTBS than did Gluma Classic. Thus, ZOE should be avoided in cavities later to be restored with resin-based materials.

  19. Detection of organochlorine compounds formed during the contact of sodium hypochlorite with dentin and dental pulp.

    PubMed

    Varise, Tiago Gilioli; Estrela, Carlos; Guedes, Débora Fernandes Costa; Sousa-Neto, Manoel Damião; Pécora, Jesus Djalma

    2014-01-01

    This study used gas chromatography-mass spectrometry (GC-MS) to detect the products formed during the contact of sodium hypochlorite (NaOCl) with bovine pulp and dentin. For analysis of the products formed in the volatile phase, 11 mg of bovine pulp tissue were placed in contact with 0.5%, 2.5% and 5.25% NaOCl until complete tissue dissolution occurred. The solid phase microextraction (SPME) fiber was exposed inside the container through the cover membrane and immediately injected into the GC-MS system. 30 mg of the of dentin were kept in contact with NaOCl, and then the SPME fiber was exposed inside the container through the cover membrane for adsorption of the products and injected into the GC-MS system. The same protocol was used for the aqueous phase. For analysis of the volatile compounds, the final solution was extracted using pure ethyl ether. The suspended particulate phase of the mixture was aspirated, and ether was separated from the aqueous phase of the solution. The ether containing the products that resulted from the chemical interaction of dentin and pulp with the NaOCl was filtered and then injected into the GC-MS system for analysis of the aqueous phase. The aqueous and volatile phases of both dentin and pulp showed the formation of chloroform, hexachloroethane, dichloromethylbenzene and benzaldehyde. In conclusion, organochlorine compounds are generated during the contact of dentin and pulp with NaOCl at concentrations of 0.5%, 2.5% and 5.25%.

  20. Accelerated fatigue of dentin with exposure to lactic acid.

    PubMed

    Do, Dominic; Orrego, Santiago; Majd, Hessam; Ryou, Heonjune; Mutluay, Mustafa M; Xu, Hockin H K; Arola, Dwayne D

    2013-11-01

    Composite restorations accumulate more biofilm than other dental materials. This increases the likelihood for the hard tissues supporting a restoration (i.e. dentin and enamel) to be exposed to acidic conditions beyond that resulting from dietary variations. In this investigation the fatigue strength and fatigue crack growth resistance of human coronal dentin were characterized within a lactic acid solution (with pH = 5) and compared to that of controls evaluated in neutral conditions (pH = 7). A comparison of the fatigue life distributions showed that the lactic acid exposure resulted in a significant reduction in the fatigue strength (p ≤ 0.001), and nearly 30% reduction in the apparent endurance limit (from 44 MPa to 32 MPa). The reduction in pH also caused a significant decrease (p ≤ 0.05) in the threshold stress intensity range required for the initiation of cyclic crack growth, and significant increase in the incremental rate of crack extension. Exposure of tooth structure to lactic acid may cause demineralization, but it also increases the likelihood of restored tooth failures via fatigue, and after short time periods.

  1. A bioartificial renal tubule device embedding human renal stem/progenitor cells.

    PubMed

    Sciancalepore, Anna Giovanna; Sallustio, Fabio; Girardo, Salvatore; Gioia Passione, Laura; Camposeo, Andrea; Mele, Elisa; Di Lorenzo, Mirella; Costantino, Vincenzo; Schena, Francesco Paolo; Pisignano, Dario

    2014-01-01

    We present a bio-inspired renal microdevice that resembles the in vivo structure of a kidney proximal tubule. For the first time, a population of tubular adult renal stem/progenitor cells (ARPCs) was embedded into a microsystem to create a bioengineered renal tubule. These cells have both multipotent differentiation abilities and an extraordinary capacity for injured renal cell regeneration. Therefore, ARPCs may be considered a promising tool for promoting regenerative processes in the kidney to treat acute and chronic renal injury. Here ARPCs were grown to confluence and exposed to a laminar fluid shear stress into the chip, in order to induce a functional cell polarization. Exposing ARPCs to fluid shear stress in the chip led the aquaporin-2 transporter to localize at their apical region and the Na(+)K(+)ATPase pump at their basolateral portion, in contrast to statically cultured ARPCs. A recovery of urea and creatinine of (20±5)% and (13±5)%, respectively, was obtained by the device. The microengineered biochip here-proposed might be an innovative "lab-on-a-chip" platform to investigate in vitro ARPCs behaviour or to test drugs for therapeutic and toxicological responses.

  2. The Composition of Bovine Peritubular Dentin: Matching TOF-SIMS, Scanning Electron Microscopy and Biochemical Component Distributions

    PubMed Central

    Gotliv, Bat Ami; Veis, Arthur

    2008-01-01

    Peritubular dentin (PTD) is a hypermineralized phase within the dentinal tubules in some vertebrate teeth as an interface between the intertubular dentin (ITD) and the cell processes. Our aim has been to understand the composition, structure and role of PTD as a mineralized tissue. We have utilized the technique of time of flight secondary ion mass spectrometry (TOF-SIMS) to map the distribution of positive and negative inorganic ions as well as organic components in the fully mineralized, intact PTD structure in bovine tooth cross-sections, and correlated these with scanning electron microscopy (SEM) in standard and backscatter modes. In recent work, we developed a procedure to freeze fracture the teeth and separate PTD from the less dense ITD by the use of aqueous sodium phosphotungstate step density gradients, after degrading the ITD collagen with NaOCl. Here, PTD-containing fragments were characterized by SEM and TOF-SIMS surface structure analysis. The TOF-SIMS data show that the isolated PTD does not contain collagen, but its surface is rich in glutamic acid-containing protein(s). The TOF-SIMS spectra also indicated that the intact PTD fragments contain phospholipids, and chemical analyses showed phosphatidylserine, phosphatidylinositol and phosphatidylcholine as the principal lipid components. In SEM sections, untreated PTD shows as a smooth collar around the tubule, but after digestion with ethylenediamine to remove all organic components, the porous nature of the mineral phase of small, thin platy apatite crystals becomes evident. Thus, the organic matrix of PTD appears to be a proteolipid-phospholipid complex. PMID:18728348

  3. Effect of the application time of phosphoric acid and self-etch adhesive systems to sclerotic dentin

    PubMed Central

    MENA-SERRANO, Alexandra Patricia; GARCIA, Eugenio Jose; PEREZ, Miguel Muñoz; MARTINS, Gislaine Cristine; GRANDE, Rosa Helena Miranda; LOGUERCIO, Alessandro Dourado; REIS, Alessandra

    2013-01-01

    Objectives: To evaluate the effect of application time on the resin-dentin bond strength (µTBS) and etching pattern of adhesive systems applied on sclerotic dentine. Material and Methods: A total of forty-two bovine incisors had their roots removed. The 1-step self-etch GO (SDI), the 2-step self-etch Adper SE Bond (3MESPE) and the 35% phosphoric acid (3MESPE) from the 2-step etch-and-rinse Adper Single Bond 2 (3MESPE) were applied on the bovine incisal surfaces according to the manufacturer's instructions or duplicating the recommended conditioning time. After adhesive application, thirty teeth were restored with composite resin, stored for 24 h in distilled water at 37º C, and sectioned into resin-dentin bonded sticks (0.8 mm2) and tested according to the µTBS at 0.5 mm/min. The etching pattern of the remaining twelve teeth (n=4 for each material) was examined under scanning electron microscopy. Each tooth was divided into a buccal-to-lingual direction into three thirds, and each third randomly assigned to the groups: control (no treatment), according to the manufacturers' instructions and duplicating the recommended application time. The µTBS and the relative percentage of the tubule area opening were evaluated by two-way repeated measures ANOVA and Tukey's tests (α=0.05). Results: The duplication of the conditioning time favored only the GO adhesive (p<0.05). Both application methods significantly increased the tubule area opening (p<0.05) compared to the controls. Conclusions: The efficacy of duplicating the conditioning time was only effective for the 1-step self-etch adhesive system tested. PMID:23739856

  4. Effects of Tetracycline, EDTA and Citric Acid Application on Nonfluorosed and Fluorosed Dentin: An In Vitro Study

    PubMed Central

    Sadanand, K.; Vandana, K. L.

    2016-01-01

    Fluorosis is one of the factors that may bring about mineralization changes in teeth. Routine treatment of root biomodification is commonly followed during Periodontal therapy. Background: The Purpose of the present study was to compare and evaluate the morphological changes in fluorosed and nonfluorosed root dentin subsequent to the application of Tetracycline, EDTA and Citric acid. Both fluorosed and nonfluorosed teeth comprising of periodontally healthy and diseased were included in this study. Method: Each of them was grouped into Tetracycline Hydrochloride, EDTA and Citric acid treatment groupes. Using scanning electron microscope (SEM), the photomicrographs of dentin specimens were obtained. Results: Showed that there was no significant difference in exposure of number of tubules in different groups, while significant increase in the tubular width and tubular surface area was seen in fluorosed healthy, followed by fluorosed diseased groups, nonfluorosed healthy and nonfluorosed diseased groups after root biomodification procedure using various root conditioning agents. The root biomodification procedure brings in definite difference between fluorosed and nonfluorosed dentin specimens. PMID:27335611

  5. Effect of MTA and Portland Cement on Fracture Resistance of Dentin.

    PubMed

    Forghani, Maryam; Bidar, Maryam; Shahrami, Fatemeh; Bagheri, Mahmoud; Mohammadi, Maryam; Attaran Mashhadi, Niloufar

    2013-01-01

    Background and aims. It is important to evaluate the effects of endodontic materials on tooth structures to avoid endodontic treatment failure. The aim of the present study was to investigate the effect of mineral trioxide aggregates (MTA) and Portland cement (PC) on fracture resistance of dentin. Materials and methods. Thirty-six freshly extracted human single-rooted premolar teeth were selected. The crowns were removed and the roots were randomly divided into two experimental groups and one control group. The root samples were longitudinally divided into two halves and a dentin bar (2×2×10 mm) was cut from each root section for short-term (2weeks) and long-term (12 weeks) evaluations. The root sections in the experimental groups were exposed to MTA or PC, while keeping the control group specimens in physiologic saline. The fracture resistance of each specimen was measured using an Instron testing machine. The results were statistically analyzed using ANOVA, a post hoc Tukey test and paired t-test at 5% significance level. Results. The fracture resistance of MTA-treated specimens significantly increased between 2 and 12 weeks (P<0.05). After 12 weeks, MTA-treated specimens had the highest fracture resistance. In the PC group, the fracture resistance of specimens did not change significantly over time (P>0.05). Conclusion. The results showed that MTA increased the fracture resistance of root dentin, while PC had no significant effect on dentin fracture resistance.

  6. How to bond to root canal dentin

    NASA Astrophysics Data System (ADS)

    Nica, Luminita; Todea, Carmen; Furtos, Gabriel; Baldea, Bogdan

    2014-01-01

    Bonding to root canal dentin may be difficult due to various factors: the structural characteristic of the root canal dentin, which is different from that of the coronal dentin; the presence of the organic tissue of the dental pulp inside the root canal, which has to be removed during the cleaning-shaping of the root canal system; the smear-layer resulted after mechanical instrumentation, which may interfere with the adhesion of the filling materials; the type of the irrigants used in the cleaning protocol; the type of the sealer and core material used in the obturation of the endodontic space; the type of the materials used for the restoration of the endodontically treated teeth. The influence of the cleaning protocol, of the root canal filling material, of the type of the adhesive system used in the restoration of the treated teeth and of the region of the root canal, on the adhesion of several filling and restorative materials to root canal dentin was evaluated in the push-out bond strength test on 1-mm thick slices of endodontically treated human teeth. The results showed that all these factors have a statistically significant influence on the push-out bond strength. Formation of resin tags between radicular dentin and the investigated materials was observed in some of the samples at SEM analysis.

  7. Scanning electron microscopy and dentinal permeability analysis of smear layer.

    PubMed

    Prati, C; Mongiorgi, R; Pashley, D H; Riva di Sanseverino, L

    1991-05-01

    The aim of the present study was to evaluate the surface morphology and the permeability of dentine after different acid treatments: polyacrylic acid, maleic acid, phosphoric acid and saline solution as control. Dentine permeability was expressed as hydraulic conductance. All the acid treatments removed the smear layer and increased the dentine permeability.

  8. Relationship between the chemical and morphological characteristics of human dentin after Er:YAG laser irradiation.

    PubMed

    Soares, Luís Eduardo Silva; Martin, Ovídio César Lavesa; Moriyama, Lilian Tan; Kurachi, Cristina; Martin, Airton Abrahão

    2013-06-01

    The effects of laser etching on dentin are studied by microenergy-dispersive x-ray fluorescence spectrometry (μ-EDXRF) and scanning electron microscopy (SEM) to establish the correlation of data obtained. Fifteen human third molars are prepared, baseline μ-EDXRF mappings are performed, and ten specimens are selected. Each specimen received four treatments: acid etching (control-CG) or erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiation (I-100 mJ, II-160 mJ, and III-220 mJ), and maps are done again. The Ca and P content are significantly reduced after acid etching (p<0.0001) and increased after laser irradiation with 220 mJ (Ca: p<0.0153 and P: p=0.0005). The Ca/P ratio increased and decreased after CG (p=0.0052) and GI (p=0.0003) treatments, respectively. CG treatment resulted in lower inorganic content (GI: p<0.05, GII: p<0.01, and GIII: p<0.01) and higher Ca/P ratios than laser etching (GI: p<0.001, GII: p<0.01, and GIII: p<0.01). The SEM photomicrographies revealed open (CG) and partially open dentin tubules (GI, GII, and GIII). μ-EDXRF mappings illustrated that acid etching created homogeneous distribution of inorganic content over dentin. Er:YAG laser etching (220 mJ) produced irregular elemental distribution and changed the stoichiometric proportions of hydroxyapatite, as showed by an increase of mineral content. Decreases and increases of mineral content in the μ-EDXRF images are correlated to holes and mounds, respectively, as found in SEM images.

  9. Dentin adhesion and MMPs: a comprehensive review.

    PubMed

    Perdigão, Jorge; Reis, Alessandra; Loguercio, Alessandro D

    2013-08-01

    This review examines the fundamental processes responsible for the aging mechanisms involved in the degradation of resin-bonded interfaces, as well as some potential approaches to prevent and counteract this degradation. Current research in several research centers aims at increasing the resin-dentin bond durability. The hydrophilic and acidic characteristics of current dentin adhesives have made hybrid layers highly prone to water sorption. This, in turn, causes polymer degradation and results in decreased resin-dentin bond strength over time. These unstable polymers inside the hybrid layer may result in denuded collagen fibers, which become vulnerable to mechanical and hydrolytical fatigue, as well as degradation by host-derived proteases with collagenolytic activity. These enzymes, such as matrix metalloproteinases and cysteine cathepsins, have a crucial role in the degradation of type I collagen, the organic component of the hybrid layer. This review will also describe several methods that have been recently advocated to silent the activity of these endogenous proteases.

  10. Dentin Matrix Proteins in Bone Tissue Engineering.

    PubMed

    Ravindran, Sriram; George, Anne

    2015-01-01

    Dentin and bone are mineralized tissue matrices comprised of collagen fibrils and reinforced with oriented crystalline hydroxyapatite. Although both tissues perform different functionalities, they are assembled and orchestrated by mesenchymal cells that synthesize both collagenous and noncollagenous proteins albeit in different proportions. The dentin matrix proteins (DMPs) have been studied in great detail in recent years due to its inherent calcium binding properties in the extracellular matrix resulting in tissue calcification. Recent studies have shown that these proteins can serve both as intracellular signaling proteins leading to induction of stem cell differentiation and also function as nucleating proteins in the extracellular matrix. These properties make the DMPs attractive candidates for bone and dentin tissue regeneration. This chapter will provide an overview of the DMPs, their functionality and their proven and possible applications with respect to bone tissue engineering.

  11. In vitro Comparative Evaluation of Tensile Bond Strength of 6th, 7th and 8th Generation Dentin Bonding Agents

    PubMed Central

    Kamble, Suresh S; Kandasamy, Baburajan; Thillaigovindan, Ranjani; Goyal, Nitin Kumar; Talukdar, Pratim; Seal, Mukut

    2015-01-01

    Background: Newer dentin bonding agents were developed to improve the quality of composite restoration and to reduce time consumption in its application. The aim of the present study was to evaluate tensile bond strength of 6th, 7th and 8th generation bonding agents by in vitro method. Materials and Methods: Selected 60 permanent teeth were assigned into 20 in each group (Group I: 6th generation bonding agent-Adper SE plus 3M ESPE, Group II: 7th generation bonding agent-G-Bond GC Corp Japan and Group III: 8th generation dentin adhesives-FuturaBond, DC, Voco, Germany). With high-speed diamond disc, coronal dentin was exposed, and selected dentin bonding agents were applied, followed by composite restoration. All samples were saved in saline for 24 h and tensile bond strength testing was done using a universal testing machine. The obtained data were tabulated and statistically analyzed using ANOVA test. Results: The tensile bond strength readings for 6th generation bonding agent was 32.2465, for 7th generation was 31.6734, and for 8th-generation dentine bonding agent was 34.74431. The highest tensile bond strength was seen in 8th generation bonding agent compared to 6th and 7th generation bonding agents. Conclusion: From the present study it can be conclude that 8th generation dentine adhesive (Futura DC, Voco, Germany) resulted in highest tensile bond strength compared to 6th (Adper SE plus, 3M ESPE) and 7th generation (G-Bond) dentin bonding agents. PMID:26028901

  12. Effect of dentin pretreatment and curing mode on the microtensile bond strength of self-adhesive resin cements

    PubMed Central

    Youm, Seung-Hyun; Jung, Kyoung-Hwa; Son, Sung-Ae; Kwon, Yong-Hoon

    2015-01-01

    PURPOSE The aim was to evaluate the effect of curing mode and different dentin surface pretreatment on microtensile bond strength (µTBS) of self-adhesive resin cements. MATERIALS AND METHODS Thirty-six extracted human permanent molars were sectioned horizontally exposing flat dentin surface. The teeth were divided into 12 groups (3 teeth/group) according to the dentin surface pretreatment methods (control, 18% EDTA, 10% Polyacrylic acid) and curing mode (self-curing vs. light-curing) of cement. After pretreatment, composite resin blocks were cemented with the following: (a) G-CEM LinkAce; (b) RelyX U200, followed by either self-curing or light-curing. After storage, the teeth were sectioned and µTBS test was performed using a microtensile testing machine. The data was statistically analyzed using one-way ANOVA, Student T-test and Scheffe's post-hoc test at P<.05 level. RESULTS For G-CEM LinkAce cement groups, polyacrylic acid pretreatment showed the highest µTBS in the self-cured group. In the light-cured group, no significant improvements were observed according to the dentin surface pretreatment. There were no significant differences between curing modes. Both dentin surface pretreatment methods helped to increase the µTBS of RelyX U200 resin cement significantly and degree of pretreatment effect was similar. No significant differences were found regarding curing modes except control groups. In the comparisons of two self-adhesive resin cements, all groups within the same pretreatment and curing mode were significantly different excluding self-cured control groups. CONCLUSION Selecting RelyX U200 used in this study and application of dentin surface pretreatment with EDTA and polyacrylic acid might be recommended to enhance the bond strength of cement to dentin. PMID:26330979

  13. Assessment of Pain Intensity in Patients with Dentin Hypersensitivity After Application of Prophylaxis Paste Based on Calcium Sodium Phosphosilicate Formula

    PubMed Central

    Chałas, Renata; Wójcik-Chęcińska, Ilona; Zamościńska, Jolanta; Bachanek, Teresa

    2015-01-01

    Background One of many functions of the pulp-dentin complex is sensory function. Acute, situated, receding pain after the cessation of the stimulus action is called dentin pain. Dentin hypersensitivity has been described as one of the most painful and least successfully treated chronic ailments of teeth. The aim of this research was the clinical evaluation of the effectiveness of professional polishing paste containing calcium sodium phosphosilicate formula (NovaMin) in eliminating dentin hypersensitivity after a single application. Material/Methods The study comprised 92 teeth with dentin hypersensitivity diagnosed on the basis of history and clinical examination. The pain reaction of exposed dentine was induced by tactile and dehydrating stimuli, asking patients to assess the severity of pain on the VAS scale. Clinical trial and survey were carried out twice: before and 1 week after the application of the polishing paste. Results After the application of the examined paste, the percentage of teeth reacting with a severe pain to the touch of the probe decreased from 16.3% to 4.3%, and with a moderate pain from 42.4% to 12%. Examination after applying dehydrating stimulus a week after carrying out the application showed a decrease in the proportion of teeth with strong pain from 28.3% to 0% and moderate pain from 38% to 15.2%. The lack of pain increased from 12% to about 50%. Conclusions The use of prophylactic professional paste with NovaMin formula in in-office procedure provides the reduction of dentin hypersensitivity noticeable by 1 week after application. PMID:26429677

  14. Polyunsaturated Fatty Acids in Lipid Bilayers and Tubules

    NASA Astrophysics Data System (ADS)

    Hirst, Linda S.; Yuan, Jing; Pramudya, Yohannes; Nguyen, Lam T.

    2007-03-01

    Omega-3 polyunsaturated fatty acids (PUFAs) are found in a variety of biological membranes and have been implicated with lipid raft formation and possible function, typical molecules include DHA (Docosahexanoic Acid) and AA (Alphalinoleic Acid) which have been the focus of considerable attention in recent years. We are interested in the phase behavior of these molecules in the lipid bilayer. The addition of lipid molecules with polyunsaturated chains has a clear effect on the fluidity and curvature of the membrane and we investigate the effects the addition of polyunsaturated lipids on bilayer structure and tubule formation. Self-assembled cylindrical lipid tubules have attracted considerable attention because of their interesting structures and potential technological applications. Using x-ray diffraction techniques, Atomic Force Microscopy and confocal fluorescence imaging, both symmetric and mixed chain lipids were incorporated into model membranes and the effects on bilayer structure and tubule formation investigated.

  15. Effects of Er:YAG laser irradiation and manipulation treatments on dentin components, part 1: Fourier transform-Raman study

    NASA Astrophysics Data System (ADS)

    Soares, Luís Eduardo Silva; Do Espírito Santo, Ana Maria; Junior, Aldo Brugnera; Zanin, Fátima Antônia Aparecida; da Silva Carvalho, Carolina; de Oliveira, Rodrigo; Martin, Airton Abraha~O.

    2009-03-01

    The effects of laser etching, decontamination, and storage treatments on dentin components were studied using Fourier transform (FT)-Raman spectroscopy. Thirty bovine incisors were prepared to expose the dentin surface and then divided in two main groups based upon the decontamination process and storage procedure: autoclaved (group A, n=15) or stored in thymol aqueous solution (group B, n=15). The surfaces of the dentin slices were schematically divided into four areas, with each one corresponding to a treatment subgroup. The specimens were either etched with phosphoric acid (control subgroup) or irradiated with erbium-doped yttrium-aluminum-garnet (Er:YAG) laser (subgroups: I-80 mJ, II-120 mJ, and III-180 mJ, and total energy of 12 J). Samples were analyzed by FT-Raman spectroscopy; we collected three spectra for each area (before and after treatment). The integrated areas of five Raman peaks were calculated to yield average spectra. The areas of the peaks associated with phosphate content (P<0.001), type I collagen, and organic C-H bonds (P<0.05) were reduced significantly in group A (control). Analyses of samples irradiated with reduced laser energies did not show significant changes in the dentin components. These results suggest that thymol storage treatment is advised for in vitro study; furthermore, 12 J of Er:YAG laser energy does not affect dentin components.

  16. Effect of desensitizing treatments on bond strength of resin composites to dentin – an in vitro study

    PubMed Central

    Makkar, Sameer; Goyal, Meenu; Kaushal, Ashih; Hegde, Vivek

    2014-01-01

    Objectives: Hypersensitivity is a common clinical multietiological problem. Many desensitizing treatments are there to overcome hypersensitivity. The aim of this study was to evaluate the effect of different dentin-desensitizing treatments on the tensile bond strength of composite restoration. Materials and Methods: Twenty-four sound human molars were used. Enamel was wet abraded to expose flat dentin surfaces, polished with sandpaper. The specimens were then divided into three groups (n = 8) based on the type of dentin-desensitizing treatment given. The first group: G1 was the control group where no desensitizing agent was used. The second group: G2 was treated with desensitizing dentifrice containing a combination of potassium nitrate, triclosan, and sodium monoflorophosphate. The third group: G3 was treated with Er:YAG laser. Afterwards, the desensitized specimens were treated with one step self-etch adhesive according to manufacturer's instructions and composite microcylinders were packed. The specimens were then examined for tensile bond strength using universal tensile machine (KMITM ). Results: Statistical analysis of the data obtained revealed the mean values for the tensile bond strengths were 10.2613 MPa, 5.9400 MPa and 6.3575 MPa for groups 1, 2 and 3, respectively. These values were statistically significantly different between groups pretreated with laser or dentifrice as compared to control group. Conclusions: Dentifrice and Laser pre-treated dentin has lower tensile bond strength with resin composites as compared to dentin that is untreated. PMID:25298648

  17. Antibacterial TAP-mimic Electrospun Polymer Scaffold – Effects on P. gingivalis-Infected Dentin Biofilm

    PubMed Central

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

    2016-01-01

    Objectives This study sought to investigate, in-vitro, the effects of a recently developed triple antibiotic paste (TAP)-mimic polymer nanofibrous scaffold against Porphyromonas gingivalis (Pg)-infected dentin biofilm. Materials and Methods Dentin specimens (4×4×1mm3) were prepared from human canines. The specimens were sterilized, inoculated with Pg (ATCC 33277), and incubated for one 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+25wt.%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/mL) (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. Results 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/mL data between antibiotic-free scaffolds (2.7 log10 CFU/mL) and the negative control (5.9 log10 CFU/mL). Conclusions The obtained data revealed significant antimicrobial properties of the novel PDS-based TAP-mimic scaffold against an established Pg-infected dentin biofilm. Clinical relevance 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. PMID:26319981

  18. Influence of etching time on bond strength in dentin irradiated with erbium lasers.

    PubMed

    Ferreira, Leila Soares; Apel, Christian; Francci, Carlos; Simoes, Alyne; Eduardo, Carlos P; Gutknecht, Norbert

    2010-11-01

    The purpose of this in vitro study was to evaluate the effect of etching time on the tensile bond strength (TBS) of a conventional adhesive bonded to dentin previously irradiated with erbium:yttrium-aluminum-garnet (Er:YAG) and erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) lasers. Buccal and lingual surfaces of 45 third molars were flattened until the dentin was exposed and randomly assigned to three groups (n = 30) according to the dentin treatment: control (not irradiated), irradiated with Er:YAG (1 W; 250 mJ; 4 Hz; 80.6 J/cm(2)) laser or Er,Cr:YSGG (4 W; 200 mJ; 20 Hz; 71.4 J/cm(2)) laser, and into three subgroups (n = 10) according to acid etching time (15 s, 30 s or 60 s) for each experimental group. After acid etching, the adhesive was applied, followed by the construction of an inverted cone of composite resin. The samples were immersed in distilled water (37 degrees C for 24 h) and subjected to TBS test [50 kilogram-force (kgf), 0.5 mm/min]. Data were analyzed by analysis of variance (ANOVA) and Tukey statistical tests (P < or = 0.05). Control group samples presented significant higher TBS values than those of all lased groups. Both irradiated groups exhibited similar TBS values. Samples subjected to the different etching times in each experimental group presented similar TBS. Based on the conditions of this in vitro study we concluded that Er:YAG and Er,Cr:YSGG laser irradiation of the dentin weakens the bond strength of the adhesive. Moreover, increased etching time is not able to modify the bonding strength of the adhesive to irradiated dentin.

  19. Bond strength of a self-adhesive resin cement to enamel and dentin.

    PubMed

    Fernandes, Virgílio Vilas Boas; Rodrigues, José Roberto; da Silva, João Maurício Ferraz; Pagani, Clovis; Souza, Rodrigo Othávio Assunção

    2015-01-01

    The purpose of this study was to evaluate the influence of surface treatments and thermocycling on the microtensile bond strength (μTBS) of self-adhesive resin cement to human enamel and dentin. Eighty human third molars were selected. The crowns of 40 teeth were transversally sectioned, exposing the mid-coronal dentin. The buccal surfaces of the other 40 teeth were grinded to obtain a 5 mm2 flat enamel area. Eighty resin blocks were produced and cemented to the dental surfaces with RelyX Unicem, then grouped according to the surface treatment (n=10): UnicemC with no conditioning, UnicemP with 37% phosphoric acid/15 s, and UnicemPA with 37% phosphoric acid/15 s plus adhesive bonding (Single Bond 2). There were two control groups, one for enamel and the other for dentin: VR with 37% phosphoric acid/15 s plus adhesive bonding (Single Bond 2) plus Variolink II. The enamel-dentin resin cement blocks were sectioned to produce non-trimmed bar specimens, which were divided into two storage conditions: dry, μTBS immediately after cutting; TC (5,000 x; 5°C/55°C). The samples were submitted to μTBS, and data were statistically analyzed by ANOVA and Tukey's test. The results showed statistical differences between UnicemC and the others. UnicemPA and VR showed better bond strength to dentin during the period before and after thermocycling, respectively. For the enamel, UnicemP showed better bond strength for both situations. Only for UnicemPA did the thermocycling significantly decrease the bond strength values. Within the limits of this study, it could be concluded that the bond strength is influenced by the surface treatments, and that thermocycling decreases the bond strength of all groups, but significantly only for UnicemPA.

  20. Radiotherapy Effect on Nano-mechanical Properties and Chemical Composition of Enamel and Dentin

    PubMed Central

    Reed, R.; Xu, C.; Liu, Y.; Gorski, J.P.; Wang, Y.; Walker, M.P.

    2015-01-01

    Objective To understand radiotherapy-induced dental lesions characterized by enamel loss or delamination near the dentin-enamel junction (DEJ), this study evaluated enamel and dentin nano-mechanical properties and chemical composition before and after simulated oral cancer radiotherapy. Design Sections from seven non-carious third molars were exposed to 2 Gy fractions, 5 days/week for 7 weeks for a total of 70 Gy. Nanoindentation was used to evaluate Young’s modulus, while Raman microspectroscopy was used to measure protein/mineral ratios, carbonate/phosphate ratios, and phosphate peak width. All measures were completed prior to and following radiation at the same four buccal and lingual sites 500 and 30 microns from the DEJ in enamel and dentin (E-500, E-30, D-30 and D-500). Results The elastic modulus of enamel and dentin was significantly increased (P≤0.05) following radiation. Based on Raman spectroscopic analysis, there was a significant decrease in the protein to mineral ratio (2931/430 cm-1) following radiation at all sites tested except at D-500, while the carbonate to phosphate ratio (1070/960 cm-1) increased at E-30 and decreased at D-500. Finally, phosphate peak width as measured by FWHM at 960 cm-1 significantly decreased at both D-30 and D-500 following radiation. Conclusions Simulated radiotherapy produced an increase in the stiffness of enamel and dentin near the DEJ. Increased stiffness is speculated to be the result of the radiation-induced decrease in the protein content, with the percent reduction much greater in the enamel sites. Such changes in mechanical properties and chemical composition could potentially contribute to DEJ biomechanical failure leading to enamel delamination that occurs post-radiotherapy. However, other analyses are required for a better understanding of radiotherapy-induced effects on tooth structure to improve preventive and restorative treatments for oral cancer patients. PMID:25766468

  1. Effects of Resin Hydrophilicity on Dentin Bond Strength

    PubMed Central

    Nishitani, Y.; Yoshiyama, M.; Donnelly, A.M.; Agee, K.A.; Sword, J.; Tay, F.R.; Pashley, D.H.

    2008-01-01

    The purpose of this study was to determine if hydrophobic resins can be coaxed into dentin wet with ethanol instead of water. The test hypothesis was that dentin wet with ethanol would produce higher bond strengths for hydrophobic resins than would dentin wet with water. This study examined the microtensile bond strength of 5 experimental adhesives (50 wt% ethanol/50% comonomers) of various degrees of hydrophilicity to acid-etched dentin that was left moist with water, moist with ethanol, or air-dried. Following composite buildups, hourglass-shaped slabs were prepared from the bonded teeth for microtensile testing. For all 3 types of dentin surfaces, higher bond strengths were achieved with increased resin hydrophilicity. The lowest bond strengths were obtained on dried dentin, while the highest bond strengths were achieved when dentin was bonded moist with ethanol. Wet-bonding with ethanol achieved higher bond strengths with hydrophobic resins than were possible with water-saturated matrices. PMID:17062742

  2. Evaluation of mineral content of dentin treated with desensitizing agents and neodymium yttrium-aluminium-garnet (Nd:YAG) laser.

    PubMed

    Malkoç, Meral Arslan; Sevimay, Müjde

    2012-07-01

    The aim of this study was to evaluate the mineral content of dentin prepared using three different desensitizing agents and the Nd:YAG laser. The occlusal third of the crowns of 30 molar teeth were cut with a slow-speed diamond saw sectioning machine under water cooling. Dentin slabs from the 30 teeth were randomly divided into five experimental groups, each comprising six slabs. The five groups were treated as follows: group A, no treatment; group B, treatment with oxalate-containing desensitizing agent (BisBlock); group C, treatment with resin-based desensitizing agent (Admira Protect); group D, treatment with glutaraldehyde-containing desensitizing agent (Systemp); and group E, irradiation with the Nd:YAG laser (DEKATM ) at 0.40 W. The levels of Mg, P, Ca, K, and Na in each slab were measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). Data were analyzed by one-way analysis of variance and the Tukey HSD test. The effect of desensitizing agents and laser irradiation on the dentin surface were evaluated using a scanning electron microscope. There were no significant differences between the groups (p > 0.05). Group E was showed the lowest Ca/P ratio. SEM showed that the resin-based agent occluded the dentinal tubules, the glutaraldehyde-containing agent increased the Ca/P ratio, and Nd:YAG laser irradiation decreased the Ca/P ratio. The mean percentages by weight of Ca, Mg, K, Na and P were not affected by Nd:YAG laser irradiation or any of the desensitizing agents.

  3. Removal of dentin matrix proteoglycans by trypsin digestion and its effect on dentin bonding.

    PubMed

    Bedran-Russo, Ana Karina B; Pereira, Patricia N R; Duarte, Wagner R; Okuyama, Katsushi; Yamauchi, Mitsuo

    2008-04-01

    The aim of this study was to investigate the effect of trypsin digestion on removal of chondroitin sulfate proteoglycans (CS-PGs) in demineralized dentin, and subsequent dentin bonding. Bovine dentin fragments were demineralized, treated with or without trypsin, stained with cupromeronic blue, and observed under transmission electron microscopy. Demineralized sections with or without trypsin digestion were also subjected to immunohistochemical analysis with anti-chondroitin-4-sulfate (C4S) monoclonal antibody, 2-B-6. The presence of galactosamine and glucosamine in the trypsin digest was confirmed by amino acid analysis. Bond strength testing was performed on trypsin treated and control specimens where samples were either kept moist or dried and re-wet, then bonded. Bond strength significantly decreased after trypsin treatment (p < 0.05). TEM, immunohistochemical, and amino acid analyses demonstrated that trypsin digestion efficiently removed C4S-PGs from demineralized dentin matrix. This study indicates that the detrimental effects observed on dentin bonding by trypsinization may be due in part to the removal/cleavage of the C4S-PGs, and further underscore the importance of C4S-PGs on dentin bonding.

  4. Dentin Biomodification Potential Depends on Polyphenol Source

    PubMed Central

    Aguiar, T.R.; Vidal, C.M.P.; Phansalkar, R.S.; Todorova, I.; Napolitano, J.G.; McAlpine, J.B.; Chen, S.N.; Pauli, G.F.; Bedran-Russo, A.K.

    2014-01-01

    Although proanthocyanidins (PACs) modify dentin, the effectiveness of different PAC sources and the correlation with their specific chemical composition are still unknown. This study describes the chemical profiling of natural PAC-rich extracts from 7 plants using ultra high pressure/performance liquid chromatography (UHPLC) to determine the overall composition of these extracts and, in parallel, comprehensively evaluate their effect on dentin properties. The total polyphenol content of the extracts was determined (as gallic acid equivalents) using Folin-Ciocalteau assays. Dentin biomodification was assessed by the modulus of elasticity, mass change, and resistance to enzymatic biodegradation. Extracts with a high polyphenol and PAC content from Vitis vinifera, Theobroma cacao, Camellia sinensis, and Pinus massoniana induced a significant increase in modulus of elasticity and mass. The UHPLC analysis showed the presence of multiple types of polyphenols, ranging from simple phenolic acids to oligomeric PACs and highly condensed tannins. Protective effect against enzymatic degradation was observed for all experimental groups; however, statistically significant differences were observed between plant extracts. The findings provide clear evidence that the dentin bioactivities of PACs are source dependent, resulting from a combination of concentration and specific chemical constitution of the complex PAC mixtures. PMID:24574140

  5. Excretory transport of xenobiotics by dogfish shark rectal gland tubules.

    PubMed

    Miller, D S; Masereeuw, R; Henson, J; Karnaky, K J

    1998-09-01

    Marine elasmobranch rectal gland is a specialized, osmoregulatory organ composed of numerous blind-ended, branched tubules emptying into a central duct. To date, NaCl excretion has been its only described function. Here we use isolated rectal gland tubule fragments from dogfish shark (Squalus acanthias), fluorescent xenobiotics, and confocal microscopy to describe a second function, xenobiotic excretion. Isolated rectal gland tubules rapidly transported the fluorescent organic anion sulforhodamine 101 from bath to lumen. Luminal accumulation was concentrative, saturable, and inhibited by cyclosporin A (CSA), chlorodinitrobenzene, leukotriene C4, and KCN. Inhibitors of renal organic anion transport (probenecid, p-aminohippurate), organic cation transport (tetraethylammonium and verapamil), and P-glycoprotein (verapamil) were without effect. Cellular accumulation of sulforhodamine 101 was not concentrative, saturable, or inhibitable. Rectal gland tubules did not secrete fluorescein, daunomycin, or a fluorescent CSA derivative. Finally, frozen rectal gland sections stained with an antibody to a hepatic canalicular multispecific organic anion transporter (cMOAT or MRP2) showed heavy and specific staining on the luminal membrane of the epithelial cells. We conclude that rectal gland is capable of active and specific excretion of xenobiotics and that such transport is mediated by a shark analog of MRP2, an ATP-driven xenobiotic transporter, but not by P-glycoprotein.

  6. Lipid tubules Formed by Flow-Controlled Hydration

    NASA Astrophysics Data System (ADS)

    Yuan, Jing; Hirst, Linda S.

    2007-03-01

    Self-assembled cylindrical tubules from lipid molecules have attracted considerable attention because of their interesting supramolecular structures and technological applications. Schnur et al. [1] reported the formation of tubular microstructures from a series of diacetylenic phospholipids after liposomes were cooled through their chain melting transition. After that, several methods have been developed to fabricate such unique microstructures mainly by means of deforming preformed Giant unilamellar vesicles. Here we present a simple strategy to construct lipid microtubules through a flow-controlled lipid hydration. Fluorescent microscopy and Confocal Laser Microscopy were used to visualize the formation and the structure of the lipid tubules. Tubules were found to develop following the direction of the dynamic flow with highly parallel alignment. At high flow speeds, partial cross-linking of the lipid tubules was observed. To demonstrate the generality of this method, different types of phospholipids, such as Phosphatidic Acid (PA), Phosphatidylserine (PS), Phosphatidylethanolamine (PE), and Phosphatidylglycerol (PG) were investigated. [1] J.M. Schnur et al, Science, 264, 945 (1994).

  7. Dynamic tubulation of mitochondria drives mitochondrial network formation.

    PubMed

    Wang, Chong; Du, Wanqing; Su, Qian Peter; Zhu, Mingli; Feng, Peiyuan; Li, Ying; Zhou, Yichen; Mi, Na; Zhu, Yueyao; Jiang, Dong; Zhang, Senyan; Zhang, Zerui; Sun, Yujie; Yu, Li

    2015-10-01

    Mitochondria form networks. Formation of mitochondrial networks is important for maintaining mitochondrial DNA integrity and interchanging mitochondrial material, whereas disruption of the mitochondrial network affects mitochondrial functions. According to the current view, mitochondrial networks are formed by fusion of individual mitochondria. Here, we report a new mechanism for formation of mitochondrial networks through KIF5B-mediated dynamic tubulation of mitochondria. We found that KIF5B pulls thin, highly dynamic tubules out of mitochondria. Fusion of these dynamic tubules, which is mediated by mitofusins, gives rise to the mitochondrial network. We further demonstrated that dynamic tubulation and fusion is sufficient for mitochondrial network formation, by reconstituting mitochondrial networks in vitro using purified fusion-competent mitochondria, recombinant KIF5B, and polymerized microtubules. Interestingly, KIF5B only controls network formation in the peripheral zone of the cell, indicating that the mitochondrial network is divided into subzones, which may be constructed by different mechanisms. Our data not only uncover an essential mechanism for mitochondrial network formation, but also reveal that different parts of the mitochondrial network are formed by different mechanisms.

  8. Natural history of seminiferous tubule degeneration in Klinefelter syndrome.

    PubMed

    Aksglaede, Lise; Wikström, Anne M; Rajpert-De Meyts, Ewa; Dunkel, Leo; Skakkebaek, Niels E; Juul, Anders

    2006-01-01

    Klinefelter syndrome (47,XXY) is characterized by small, firm testis, gynaecomastia, azoospermia and hypergonadotropic hypogonadism. Degeneration of the seminiferous tubules in 47,XXY males is a well-described phenomenon. It begins in the fetus, progresses through infancy and accelerates dramatically at the time of puberty with complete hyalinization of the seminiferous tubules, although a few tubules with spermatogenesis may be present in adult life. Activation of the pituitary-gonadal axis at 3 months of age is seen in Klinefelter boys similar to healthy boys. However, the level of testosterone in Klinefelter boys is significantly lower than in controls. After this 'minipuberty', the hormone levels decline to normal prepubertal levels until puberty. In puberty, an initial rise in testosterone, inhibin B, LH and FSH occurs in Klinefelter boys. However, the rise in testosterone levels off and ends at a low-normal level in young adults. Likewise, serum concentration of inhibin B exhibits a dramatic decline to a low, often undetectable level, concomitantly with a rise in FSH, reflecting the degeneration of the seminiferous tubules. Many hypotheses about the underlying mechanism of the depletion of the germ cells in Klinefelter males have been reported and include insufficient supranumerary X-chromosome inactivation, Leydig cell insufficiency and disturbed regulation of apoptosis of Sertoli and Leydig cells. However, at present, the exact mechanism remains unclear. In this article, we summarize current knowledge on the development of the classical endocrinological and histological features of 47,XXY males from fetus to adulthood and review the literature concerning the degeneration of the seminiferous tubules in this syndrome.

  9. Studies of the electrical potential difference in rat proximal tubule.

    PubMed

    Seely, J F; Chirito, E

    1975-07-01

    The electrical potential difference (PD) in the rat proximal convoluted tubule was investigated in vivo as a function of distance from the glomerulus. The PD was found to be invariably negative (up to -4.5 mV) in the earliest segments (less than 0.5 mm from the glomerulus) and rose to positive values (+2 to +4) in the later segments (1 mm beyond the glomerulus). This change in PD correlated with the bubule fluid-to-plasma (TF/P) chloride ratios, which rose from unity in the early segments to approximately 1.3 in the late. Corresponding changes in PD and chloride ratios could be elicited by single-nephron stop-flow techniques in the early segments. Luminal perfusion techniques demonstrated a direct relationship between PD and tubule fluid chloride concentration. Acetazolamide was found to significantly reduce both late proximal PD (less than +2 mV) and TF/P chloride ratios (less than 1.06). Split-drop studies demonstrated that the negative PD in the early proximal tubule was dependent on the presence of glucose and alanine and the absence of a chloride gradient, whereas in the late proximal tubule under the same conditions the PD was not significantly different from zero. In this segment of the nephron the positive PD in free flow appeared to result from the chloride diffusion potential generated by preferential HCO3 reabsorption. These results provide further demonstration of intrinsic differences in the transport properties along the length of the proximal convoluted tubule.

  10. CFTR mediated chloride secretion in the avian renal proximal tubule.

    PubMed

    Laverty, Gary; Anttila, Ashley; Carty, Jenava; Reddy, Varudhini; Yum, Jamie; Arnason, Sighvatur S

    2012-01-01

    In primary cell cultures of the avian (Gallus gallus) renal proximal tubule parathyroid hormone and cAMP activation generate a Cl(-)-dependent short circuit current (I(SC)) response, consistent with net transepithelial Cl(-) secretion. In this study we investigated the expression and physiological function of the Na-K-2Cl (NKCC) transporter and CFTR chloride channel, both associated with Cl(-) secretion in a variety of tissues, in these proximal tubule cells. Using both RT-PCR and immunoblotting approaches, we showed that NKCC and CFTR are expressed, both in proximal tubule primary cultures and in a proximal tubule fraction of non-cultured (native tissue) fragments. We also used electrophysiological methods to assess the functional contribution of NKCC and CFTR to forskolin-activated I(SC) responses in filter grown cultured monolayers. Bumetanide (10 μM), a specific blocker of NKCC, inhibited forskolin activated I(SC) by about 40%, suggesting that basolateral uptake of Cl(-) is partially mediated by NKCC transport. In monolayers permeabilized on the basolateral side with nystatin, forskolin activated an apical Cl(-) conductance, manifested as bidirectional diffusion currents in the presence of oppositely directed Cl(-) gradients. Under these conditions the apical conductance appeared to show some bias towards apical-to-basolateral Cl(-) current. Two selective CFTR blockers, CFTR Inhibitor 172 and GlyH-101 (both at 20 μM) inhibited the forskolin activated diffusion currents by 38-68%, with GlyH-101 having a greater effect. These data support the conclusion that avian renal proximal tubules utilize an apical CFTR Cl(-) channel to mediate cAMP-activated Cl(-) secretion.

  11. Does immediate dentin sealing influence the polymerization of impression materials?

    PubMed Central

    Ghiggi, Paula Cristine; Steiger, Arno Kieling; Marcondes, Maurem Leitão; Mota, Eduardo Gonçalves; Burnett, Luiz Henrique; Spohr, Ana Maria

    2014-01-01

    Objectives: The objective of the following study is to evaluate the interaction between the resin materials used in immediate dentin sealing (IDS) techniques and impression materials with two different techniques to eliminate the oxygen-inhibition layer. Materials and Methods: The occlusal dentin surface of 35 human molars was exposed. The teeth were used in two Groups: Group 1 – Impression with Express XT; Group 2 – Impression with Impregum. Groups 1 and 2 were divided into 14 subgroups: Groups 1a and 2a – Control groups; 1b and 2b – IDS with Clearfil SE Bond (CSE); 1c and 2c – IDS with CSE + additional polymerization with glycerin jelly; 1d and 2d – IDS with CSE + alcohol; 1e and 2e – IDS with CSE and Protect Liner F (PLF); 1f and 2f – IDS with CSE and PLF + additional polymerization with glycerin jelly; and 1g and 2g – IDS with CSE and PLF + alcohol. Five teeth were used in each experimental group, and the tooth surface was photographed using a digital camera. Results: Small quantity of unpolymerized impression material remained attached to the CSE or to the PLF in Groups 1b and 1e. Groups 1c and 1d prevented the interaction. Small quantity of polymerized impression material remained attached to the CSE or to the PLF for Groups 2b and 2e. The same interaction was observed for Groups 2c and 2d. For Groups 2c and 2f, no interactions were observed. Conclusion: Resin materials interacted with impression materials. The application of glycerin jelly and alcohol prevented the interaction of CSE with Express XT and PLF with Impregum; however, these treatments were not completely effective in preventing the interaction of CSE with Impregum and PLF with Express XT. PMID:25202218

  12. Human dental pulp stem cells cultured onto dentin derived scaffold can regenerate dentin-like tissue in vivo.

    PubMed

    Tran, Ha Le Bao; Doan, Vu Nguyen

    2015-12-01

    Regeneration of dentin tissues in the pulp space of teeth serves the ultimate goal of preserving teeth via endodontic approaches. In recent times, many studies suggested that human dentin scaffolds combined with dental stem cells was a potential strategy for the complete dentin tissue regeneration. In this study, human dental pulp stem cells (DPSCs) were isolated and cultured. Dentin specimens were prepared from human third molars and treated with ethylene diamine tetra-acetic acid and citric acid to remove the smear layer. Then, DPSCs were cultured onto human treated dentin (hTD) and implanted in mouse model for 4, 6 and 8 weeks. The resulting grafts were assessed by hematoxylin and eosin stain and immunohistochemical stains. As a result, DPSCs were supported and induced to regenerate of dentin-like tissues which expressed specific dentin markers such as dentin sialophosphoprotein and dentin matrix protein 1 by combination with hTD in vivo. Furthermore, cells existed in the newly-formed dentin-like tissues also expressed typical human mitochondria antibodies, demonstrated that new tissues originated from human. In conclusion, the obtain results extend hopefully newly-established therapy to apply in endodontics and traumatic dental hard tissues.

  13. Frameshift mutations in dentin phosphoprotein and dependence of dentin disease phenotype on mutation location.

    PubMed

    Nieminen, Pekka; Papagiannoulis-Lascarides, Lisa; Waltimo-Siren, Janna; Ollila, Päivi; Karjalainen, Sara; Arte, Sirpa; Veerkamp, Jaap; Tallon Walton, Victoria; Chimenos Küstner, Eduard; Siltanen, Tarja; Holappa, Heidi; Lukinmaa, Pirjo-Liisa; Alaluusua, Satu

    2011-04-01

    We describe results from a mutational analysis of the region of the dentin sialophosphoprotein (DSPP) gene encoding dentin phosphoprotein (DPP) in 12 families with dominantly inherited dentin diseases. In eight families (five mutations in the N-terminal third of DPP), the clinical and radiologic features were uniform and compatible with dentin dysplasia type II (DD-II) with major clinical signs in the deciduous dentition. In the other families (four mutations in the more C-terminal part), the permanent teeth also were affected, and the diseases could be classified as variants of dentinogenesis imperfecta. Attrition was not prominent, but periapical infections were common. Discoloring with varying intensity was evident, and pulps and root canals were obliterated in the permanent dentition. All mutations caused a frameshift that replaced the Ser-Ser-Asx repeat by a code for a hydrophobic downstream sequence of approximately original length. We conclude that frameshift mutations in DSPP explain a significant part of dentin diseases. Furthermore, we propose that the location of the mutation is reflected in the phenotypic features as a gradient from DD-II to more severe disease that does not conform to the classic definitions of DI-II.

  14. The microhardness of bleached dentine and its bond strength to a dentine bonding agent.

    PubMed

    Dadoun, M P; Bartlett, D W

    2007-09-01

    The aim of this study was to measure the hardness of a bleached dentine surface and its bond strength to a dentine-bonding agent. Thirty teeth were randomly divided into a test and control group. The teeth were hemi-sectioned, the cut surfaces ground flat and the test surfaces bleached with a 10% aqueous solution of carbamide peroxide continuously for 4 days. Hardness was determined using a Vickers microhardness test. The bond between Coltene 'One Coat Bond' and bleached and unbleached dentine was evaluated by measuring shear bond strength using an Instron machine. The mean hardness of dentine before and after bleaching was 62.5 (10.2) and 53.6 (7.3) and this difference was statistically different (p<0.001). For the controls immersed in water the hardness was before 60.8 (standard deviation: 7.2) and after 59.6 (8.2) respectively. The mean shear bond strength for the unbleached was 5.5MPa (1.6) and for the bleached samples was 3.3MPa (1.8) and this difference was statistically significant (p<0.002). Under these study conditions the Vickers hardness and bond strength to dentine was reduced by bleaching.

  15. Effect of dentin location and long-term water storage on bonding effectiveness of dentin adhesives.

    PubMed

    De Munck, Jan; Mine, Atsushi; Vivan Cardoso, Marcio; De Almeida Neves, Aline; Van Landuyt, Kirsten L; Poitevin, André; Van Meerbeek, Bart

    2011-01-01

    Dentin is a variable substrate with properties that change considerable in a single surface. The purpose of this study was to evaluate the bonding effectiveness to these different dentin locations and evaluate these differences over time. After bonding procedures with five different adhesives, small micro-tensile bond strength (µTBS) beams were prepared and dichotomously divided in 'center' and 'periphery' dentin specimens. After 1 week, 3, 6 and 12 months of water storage the µTBS of specimens of each group was determined, enabling a paired study design. The bond strengths of both etch&rinse adhesives were insensitive to regional variability. For the two-step self-etch adhesives, a marked increase in bond strengths was observed with increasing amount of intertubular dentin. Regional variability did not affect the long-term bonding effectiveness for any of the adhesives tested. In conclusion, only for the mild self-etch adhesives, µTBS to 'periphery' dentin was higher than for the 'center' specimens.

  16. 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

  17. SEM evaluation of nanoparticulate silver penetration into dentine collagen matrix

    NASA Astrophysics Data System (ADS)

    Bessudnova, Nadezda O.; Bilenko, David I.; Venig, Sergey B.

    2014-01-01

    In the present study a novel approach to caries management based on the application of nanoparticles of different nature to increase the mineral phase of demineralized dentin has been developed. Silver nanoparticles have been tested as a material for dentine matrix infiltration. Research findings clearly show that collagen fibers of demineralized dentine could be considered as a scaffold for mineral component delivery and the place where mineral growth can occur.

  18. AutoTT: automated detection and analysis of T-tubule architecture in cardiomyocytes.

    PubMed

    Guo, Ang; Song, Long-Sheng

    2014-06-17

    Cardiac transverse (T)-tubules provide a specialized structure for synchronization and stabilization of sarcoplasmic reticulum Ca(2+) release in healthy cardiomyocytes. The application of laser scanning confocal microscopy and the use of fluorescent lipophilic membrane dyes have boosted the discoveries that T-tubule remodeling is a significant factor contributing to cardiac contractile dysfunction. However, the analysis and quantification of the remodeling of T-tubules have been a challenge and remain inconsistent among different research laboratories. Fast Fourier transformation (FFT) is the major analysis method applied to calculate the spatial frequency spectrum, which is used to represent the regularity of T-tubule systems. However, this approach is flawed because the density of T-tubules as well as non-T-tubule signals in the images influence the spectrum power generated by FFT. Preprocessing of images and topological architecture extracting is necessary to remove non-T-tubule noise from the analysis. In addition, manual analysis of images is time consuming and prone to errors and investigator bias. Therefore, we developed AutoTT, an automated analysis program that incorporates image processing, morphological feature extraction, and FFT analysis of spectrum power. The underlying algorithm is implemented in MATLAB (The MathWorks, Natick, MA). The program outputs the densities of transversely oriented T-tubules and longitudinally oriented T-tubules, power spectrum of the overall T-tubule systems, and averaged spacing of T-tubules. We also combined the density and regularity of T-tubules to give an index of T-tubule integrity (TTint), which provides a global evaluation of T-tubule alterations. In summary, AutoTT provides a reliable, easy to use, and fast approach for analyzing myocyte T-tubules. This program can also be applied to measure the density and integrity of other cellular structures.

  19. Biostability of the Proanthocyanidins-Dentin Complex and Adhesion Studies.

    PubMed

    Leme-Kraus, A A; Aydin, B; Vidal, C M P; Phansalkar, R M; Nam, J W; McAlpine, J; Pauli, G F; Chen, S; Bedran-Russo, A K

    2017-04-01

    Oligomeric proanthocyanidins (OPACs) are potent and renewable natural bioactives possible to be refined into chemically standardized mixtures for biological applications. Herein, we found that multiscale interactions of OPACs with the dentin matrix create tight biointerfaces with hydrophobic methacrylate adhesives on wet surfaces. An enriched mixture of OPACs, with a known phytochemical profile, was produced from grape seed crude extract ( Vitis vinifera; enriched grape seed extract [e-GSE]) and applied to dentin matrices to determine changes to the mechanical properties and biodegradability of the dentin matrix and favorable resin adhesion mechanisms. Methods included a 3-point flexural test, quantification of hydroxyproline (collagen solubilization), static and dynamic nanomechanical analyses, resin-dentin microtensile bond strength, and micropermeability at the adhesive interface. The e-GSE-modified dentin matrix exhibited remarkably low collagen solubilization and sustained the bulk elastic properties over 12 mo. Tan δ findings reveal a more elastic-like behavior of the e-GSE-modified dentin matrix, which was not affected by H-bond destabilization by urea. Dentin-methacrylate biointerfaces with robust and stable adhesion were created on e-GSE-primed dentin surfaces, leading to a dramatic decrease of the interfacial permeability. Standardized OPAC mixtures provide a new mechanism of adhesion to type I collagen-rich tissues that does not rely on hydrophilic monomers. The bioadhesion mechanism involves physicochemical modifications to the dentin matrix, reduced tissue biodegradation, and bridging to methacrylate resins.

  20. Dentin permeability: effects of endodontic procedures on root slabs.

    PubMed

    Fogel, H M; Pashley, D H

    1990-09-01

    The permeability of human radicular dentin was measured as a hydraulic conductance before and after treatment with K files and before and after subsequent treatment of the endodontic smear layer with NaOCl, 50% citric acid, or 3% monopotassium-monohydrogen oxalate. Filing reduced dentin permeability 25 to 49%, respectively, depending upon whether outer or inner root dentin was filed. The permeability of these smear layers was unaffected by 5% NaOCl but increased many times after treatment with 50% citric acid for 2 min. Oxalate treatment lowered root dentin permeability to levels below that produced by creation of smear layers due to the production of a crystalline precipitate.

  1. Mantle dentine in man--a quantitative microradiographic study.

    PubMed

    Herr, P; Holz, J; Baume, L J

    1986-06-01

    50 microradiographs taken in a standardized manner of midsagittal ground sections of teeth of individuals aged 18 to 56 years were densitometrically evaluated along a track passing through enamel, dentine and an aluminium stepwedge. Semi-quantitative analysis of mineral density uniformly showed an irregular platform representing circumpulpal dentine and a peripheral down slope in the region of the amelodentinal junction, representing mantle dentine. The width of this less mineralized peripheral zone measured on densitometric recordings averaged 150 microns (+/- 50). Quantitative analysis of the two dentinal regions permitted the calculation of the mineral content in terms of volume percentage using both a graphic method and an electronic computer method. The sections were also examined by polarized light microscopy which clearly visualized the presence of peripheral mantle dentine. The mean mineral density of circumpulpal dentine was 46% according to both the graphic and the computer methods; mantle dentine yielded means close to 42% according by both methods. The 4% difference in density between circumpulpal dentine and mantle dentine proved to be statistically significant; there was no significant difference between the means obtained graphically and those obtained electronically. The need for further investigation of this region of the amelodentinal junction was stressed.

  2. Photosensitizer and light diffusion through dentin in photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Nogueira, Ana C.; Graciano, Ariane X.; Nagata, Juliana Y.; Fujimaki, Mitsue; Terada, Raquel S. S.; Bento, Antonio C.; Astrath, Nelson G. C.; Baesso, Mauro L.

    2013-05-01

    Photodynamic therapy has been considered a potential antimicrobial modality against oral infections, including dental caries. A model to estimate the penetration of both photosensitizers and light through human dentin, a factor of interest in photodynamic therapy, is proposed. The photoacoustic spectroscopy technique was used to evaluate in vitro dentin permeability of three different photosensitizers. Using the dentin optical absorption and scattering coefficients, it was possible to propose a semi-quantitative model predicting both photosensitizer and light doses within dentin. The graphic illustrations obtained provided guidelines that may be useful in photodynamic therapy protocols used as antimicrobial tools in caries lesions.

  3. Effect of cleaning dentine with soap and pumice on shear bond strength of dentine-bonding agents.

    PubMed

    Bachmann, M; Paul, S J; Lüthy, H; Schärer, P

    1997-06-01

    This in vitro study reports on the cleaning effect of different soaps on the shear bond strength of various dentine-bonding agents. Human teeth were coated with provisional cements for 24 h or for 14 days. After removing the provisional cements with a scaler, the dentinal surface was cleaned with a cotton pellet and non-fluoridated flour of pumice and soap for 10 sec. Different dentine-bonding agents and a luting resin were bonded to the dentinal surface according to manufacturers' instructions with the bonding agent and the composite material being light-cured at the same time. The bonding agents were tested under intrapulpal pressure and with thermal cycling to imitate physiological conditions. Compared with cleaning the dentine with water and pumice, all soaps investigated in this study decreased the shear bond strength values of the tested dentine-bonding agents considerably.

  4. Chemical treatment of the intra-canal dentin surface: a new approach to modify dentin hydrophobicity

    PubMed Central

    GAITAN-FONSECA, Cesar; COLLART-DUTILLEUL, Pierre-Yves; SEMETEY, Vincent; ROMIEU, Olivier; CRUZ, Roel; FLORES, Hector; CUISINIER, Frédéric; PÉREZ, Elías; POZOS-GUILLEN, Amaury

    2013-01-01

    Objective: This study evaluated the hydrophobicity of dentin surfaces that were modified through chemical silanization with octadecyltrichlorosilane (OTS). Material and Methods: An in vitro experimental study was performed using 40 human permanent incisors that were divided into the following two groups: non-silanized and silanized. The specimens were pretreated and chemically modified with OTS. After the chemical modification, the dentin hydrophobicity was examined using a water contact angle measurement (WCA). The effectiveness of the modification of hydrophobicity was verified by the fluid permeability test (FPT). Results and Conclusions: Statistically significant differences were found in the values of WCA and FPT between the two groups. After silanization, the hydrophobic intraradicular dentin surface exhibited in vitro properties that limit fluid penetration into the sealed root canal. This chemical treatment is a new approach for improving the sealing of the root canal system. PMID:23559114

  5. Clinical effectiveness of contemporary dentin bonding agents

    PubMed Central

    Krithikadatta, Jogikalmat

    2010-01-01

    Aim: The purpose of this paper is to review the literature on the clinical effectiveness of contemporary resin-based dentin bonding agents primarily focussing on the longevity of restoration. Materials and Methods: The literature published from June 2004 up to September 2010 was reviewed for clinical trials that tested the effectiveness of dentin bonding agents in the longevity of noncarious class V restoration. Results of each study reported using the USPHS criteria for clinical assessment of restoration were included and tabulated. The American Dental Association guidelines for dentin and enamel adhesives were used as a reference to compare the performance of individual bonding agents. Kruskal–Wallis followed by Mann–Whitney U was done to compare the mean Alfa score percentage for the three categories of bonding systems [etch-and-rinse (ER), self-etch primer (SEP), and self-etch-adhesive (SEA)]. Results: A comparison of the mean Alfa score percentages revealed no difference between the ER, SEP, and SEA categories of bonding systems except for marginal adaptation where ER was found to be superior to SEA. Conclusion: The clinical effectiveness of resin-based bonding agents is comparable among the three categories. PMID:21217944

  6. Chlorhexidine preserves dentin bond in vitro.

    PubMed

    Carrilho, M R O; Carvalho, R M; de Goes, M F; di Hipólito, V; Geraldeli, S; Tay, F R; Pashley, D H; Tjäderhane, L

    2007-01-01

    Loss of hybrid layer integrity compromises resin-dentin bond stability. Matrix metalloproteinases (MMPs) may be partially responsible for hybrid layer degradation. Since chlorhexidine inhibits MMPs, we hypothesized that chlorhexidine would decelerate the loss of resin-dentin bonds. Class I preparations in extracted third molars were sectioned into two halves. One half was customarily restored (etch-and-rinse adhesive/resin composite), and the other was treated with 2% chlorhexidine after being acid-etched before restoration. Specimens were stored in artificial saliva with/without protease inhibitors. Microtensile bond strengths and failure mode distribution under SEM were analyzed immediately after specimens' preparation and 6 months later. With chlorhexidine, significantly better preservation of bond strength was observed after 6 months; protease inhibitors in the storage medium had no effect. Failure analysis showed significantly less failure in the hybrid layer with chlorhexidine, compared with controls after 6 months. In conclusion, this in vitro study suggests that chlorhexidine might be useful for the preservation of dentin bond strength.

  7. Caries-resistant bonding layer in dentin

    PubMed Central

    Zhou, Wei; Niu, Li-na; Hu, Lin; Jiao, Kai; Chang, Gang; Shen, Li-juan; Tay, Franklin R.; Chen, Ji-hua

    2016-01-01

    The present study examined the mechanism for caries resistance and the pulp responses in vital teeth following the use of the augmented-pressure adhesive displacement technique. Dentin adhesives were applied to the surface of sound dentin disks in 4 experimental groups: non-antibacterial adhesive and gentle adhesive displacement (N-G), non-antibacterial adhesive and augmented-pressure adhesive displacement (N-H), antibacterial adhesive and gentle adhesive displacement (A-G), antibacterial adhesive and augmented-pressure adhesive displacement (A-H). The depth of demineralization induced by biological or chemical demineralization models was measured using confocal laser scanning microscopy and analyzed with two-way ANOVA. Pulp responses of vital dog’s teeth to the augmented-pressure adhesive displacement technique were evaluated using light microscopy. Depth of demineralization was significantly affected by “adhesive type” and “intensity of adhesive displacement” for biological demineralization. For chemical demineralization, only “intensity of adhesive displacement” showed significant influence on lesion depth. Pulp response of 0.1, 0.2 and 0.3 MPa groups showed only moderate disorganization of the odontoblast layer at 24 hours that completely re-organized after 3 weeks. Augmented-pressure adhesive displacement improves the caries resistance property of bonded dentin and does not cause irreversible pulpal damage to vital teeth when the air pressure employed is equal or smaller than 0.3 MPa. PMID:27599621

  8. Triazine monomers and their adhesion to dentin.

    PubMed

    Lee, C H; Liu, X Q; Gong, X Q

    1986-12-01

    A series of 4,6-dichloro-1,3,5-triazines [e.g., 2-allylamino-(ADT), diallylamino-(DADT), 2-N-p-allyloxyphenylamino-, 2-N-allyl-N-phenylamino-, and 2-N-allyl-N-p-tolylamino-4,6-dichloro-1,3,5-triazine] was synthesized and characterized by IR, NMR, and mass spectrometry. These monomers have chlorine atoms that can react with NH2 or OH groups and double bonds capable of copolymerization. Aniline reacted readily with ADT and DADT, ethanol reacted with ADT, but acetone, H2O, and DMF did not react with either triazine. It appears that ADT or DADT will react with dentinal collagen through NH2 or OH groups in the peptide side-chains. An aprotic solvent should be used for ADT or DADT, but absolute dryness in clinical usage is not essential because of the slow hydrolysis of ADT and DADT. Stability of the N-di-substituted amino derivative (DADT) is greater than that of the mono-substituted compound (ADT), which may isomerize. ADT and methyl methacrylate were copolymerized at 37 degrees C with amine-peroxide. ADT solutions enhanced the adhesive strength of restorative resin to dentin. Thus, monomers such as ADT and DADT appear to be promising dentin-bonding agents.

  9. From cyst to tubule: innovations in vertebrate spermatogenesis.

    PubMed

    Yoshida, Shosei

    2016-01-01

    Although vertebrates share many common traits, their germline development and function exhibit significant divergence. In particular, this article focuses on their spermatogenesis. The fundamental elements that constitute vertebrate spermatogenesis and the evolutionary changes that occurred upon transition from water to land will be discussed. The life-long continuity of spermatogenesis is supported by the function of stem cells. Series of mitotic and meiotic germ cell divisions are 'incomplete' due to incomplete cytokinesis, forming syncytia interconnected via intercellular bridges (ICBs). Throughout this process, germ cells are supported by appropriate microenvironments established primarily by somatic Sertoli cells. In anamniotes (fish and amphibians) spermatogenesis progresses in cysts, in which developing germ cell syncytia are individually encapsulated by Sertoli cells. Accordingly, Sertoli cells undergo turnover with germ cells that they nourish. This mode of cystic spermatogenesis is also observed in nonvertebrates as insects. In amniotes (reptiles, birds, and mammals), however, Sertoli cells do not turn over but comprise a persistent structure of seminiferous tubules. Sertoli cells nourish different stages of germ cells simultaneously in distinct regions of their surface. This function of Sertoli cells is spatiotemporally orchestrated, and the seminiferous epithelial cycle and spermatogenic wave make the seminiferous tubules a high-throughput factory for sperm production. Furthermore, contrary to the organized differentiating cells, undifferentiated spermatogonia that comprise the stem cell compartment exhibit active motion over the basal layer of seminiferous tubules and the frequent breakdown of ICBs. Thus, amniote seminiferous tubules represent a typical facultative (or open) niche environment without a stem cell tethering anatomically defined niche. WIREs Dev Biol 2016, 5:119-131. doi: 10.1002/wdev.204 For further resources related to this article

  10. The Mechanism of Formation of Lipid Tubules from Liposomes

    DTIC Science & Technology

    1988-01-01

    structures about 10 in diameter and as longt as hundreds of micrometers. To elucidate the nature of the conversion process. freeze fracture electron...microscopy was utilized to examine samples that were rapidly quenched during tubule fOrmation. Many transitional structures -Acre obserjed. typically...that form unusual tubular structures [1-61. tain trapped liposomes (Fig. 1). When liposomes The lecithin 1.2-bis( l.l2-tricosadiynoyl)-sn-gly- are

  11. Structure of Lipid Tubules Formed from a Polymerizable Lecithin

    DTIC Science & Technology

    1985-01-01

    Structural errecui cochleate cylinders derives from the fact that when the ntepoodmezoafbsaammrns.I i.Ch’.Sc Ca i chlatd ay fom he hosbatiylsrin. lrge 104...q~ Th ... .... -- STRUCTURE OF LIPID TUBULES FORMED N F ROMN A POLYMIERIZABLE LECITHIN NPAUL YAGER,* PAULL E. SCHOEN,* CAROL DAVIES.: RONALD...phospholipids in aqueous the chemistry and structure of DC:PC. including monitor- dispersion (Bangham et al., 1965), pure tecithins have ing the

  12. Dentin glycoprotein: the protein in the middle of the dentin sialophosphoprotein chimera.

    PubMed

    Yamakoshi, Yasuo; Hu, Jan C-C; Fukae, Makoto; Zhang, Hengmin; Simmer, James P

    2005-04-29

    Dentin sialophosphoprotein (DSPP) is a major secretory product of odontoblasts and is critical for proper dentin formation. DSPP is believed to be processed into only two structural/functional domains: dentin sialoprotein (DSP) and dentin phosphoprotein (DPP). Here we report the isolation and characterization of a third domain of DSPP, designated dentin glycoprotein (DGP). DGP was isolated from a guanidine/EDTA extract of porcine tooth dentin by ion exchange, hydroxyapatite affinity, size exclusion, and RP-HPL chromatography. Endoproteinase lysine C digestion products of DGP were characterized by Edman sequencing and mass spectrometry. The porcine DGP backbone is the 81-amino acid segment of DSPP (Ser392 to Gly472) between the DSP and DPP domains. DGP has four phosphorylated serine residues (Ser453, Ser455, Ser457, and Ser462) and one glycosylated asparagine (Asn397). There are no other post-translational modifications. DGP is a stains-all positive protein with an apparent molecular mass on SDS-PAGE of 19 kDa, which is reduced by glycopeptidase A digestion to 16 kDa. A variety of glycans can be linked to Asn397. All are complex biantennary structures with a common N-linked pentasaccharide core (mannose3-N-acetylglucosamine2), most with a fucosyl residue on the innermost N-acetylglucosamine. The alpha1-3 and alpha1-6 arms are always galactose beta1-4 N-acetylglucosamine beta1-2 mannose, and either or both arms can be unsialidated or monosialidated. The calculated monoisotopic molecular masses of the different glycosylated forms of the DGP phosphoprotein are: unsialidated 10,523 and 10,670, monosialidated 10,815 and 10,961, and disialidated 11,106, and 11,252 Da, with the disialidated forms being the most abundant.

  13. Effect of irradiation mode and filling technique on resin/dentin bonding strength in Class I cavities.

    PubMed

    dos Santos, Alex José Souza; Giannini, Marcelo; Paulillo, Luis Alexandre Maffei Sartini; Lovadino, José Roberto; de Carvalho, Ricardo Marins

    2004-01-01

    Factors such as light-curing mode, filling technique and cavity configuration may affect the bonding strength to dentin. This study evaluated the effect of irradiation mode and filling technique on resin/dentin bonding strength on the buccal wall of Class I cavities in human teeth. Occlusal enamel was removed to expose a flat dentin surface. Occlusal cavities (4 x 3 x 3 mm) were prepared in dentin. The adhesive Single Bond was applied according to the manufacturer's instructions and TPH Spectrum composite resin was placed using the following: oblique incremental, horizontal incremental or bulk filling techniques. The composite resin was light-cured either by continuous (600 mW/cm2 for 40 s) or Soft-Start (250 mW/cm2 for 10 s + 600 mW/cm2 for 30 s) modes. Specimens of the control group were obtained by bonding the material to the flat exposed buccal wall of the cavity (C-factor = 1). The teeth were stored in water at 37 degrees C for 24 h and prepared for microtensile testing. Bonded beams of approximately 0.8 mm2 were obtained from the buccal wall and tested with a tension of 0.5 mm/min. Results were analyzed by two-way ANOVA, Tukey's test and Dunnett's test (alpha = 0.05). Incremental placement techniques with both irradiation modes produced higher bonding strength values than the bulk technique (p < 0.05). Bonding strength tested in the cavities had lower values than those obtained in flat dentin surfaces (control group) (p < 0.05), except for incremental fillings using stepped irradiation. Bonding strength to the cavity walls depends on the filling technique and on the irradiation mode of composite resins.

  14. Effect of high energy X-ray irradiation on the nano-mechanical properties of human enamel and dentine.

    PubMed

    Liang, Xue; Zhang, Jing Yang; Cheng, Iek Ka; Li, Ji Yao

    2016-01-01

    Radiotherapy for malignancies in the head and neck can cause common complications that can result in tooth damage that are also known as radiation caries. The aim of this study was to examine damage to the surface topography and calculate changes in friction behavior and the nano-mechanical properties (elastic modulus, nanohardness and friction coefficient) of enamel and dentine from extracted human third molars caused by exposure to radiation. Enamel and dentine samples from 50 human third molars were randomly assigned to four test groups or a control group. The test groups were exposed to high energy X-rays at 2 Gy/day, 5 days/week for 5 days (10 Gy group), 15 days (30 Gy group), 25 days (50 Gy group), 35 days (70 Gy group); the control group was not exposed. The nanohardness, elastic modulus, and friction coefficient were analyzed using a Hysitron Triboindenter. The nano-mechanical properties of both enamel and dentine showed significant dose-response relationships. The nanohardness and elastic modulus were most variable between 30-50 Gy, while the friction coefficient was most variable between 0-10 Gy for dentine and 30-50 Gy for enamel. After exposure to X-rays, the fracture resistance of the teeth clearly decreased (rapidly increasing friction coefficient with increasing doses under the same load), and they were more fragile. These nano-mechanical changes in dental hard tissue may increase the susceptibility to caries. Radiotherapy caused nano-mechanical changes in dentine and enamel that were dose related. The key doses were 30-50 Gy and the key time points occurred during the 15th-25th days of treatment, which is when application of measures to prevent radiation caries should be considered.

  15. Dentin erosion simulation by cantilever beam fatigue and pH change.

    PubMed

    Staninec, M; Nalla, R K; Hilton, J F; Ritchie, R O; Watanabe, L G; Nonomura, G; Marshall, G W; Marshall, S J

    2005-04-01

    Exposed root surfaces frequently exhibit non-carious notches representing material loss by abrasion, erosion, and/or abfraction. Although a contribution from mechanical stress is often mentioned, no definitive proof exists of a cause-effect relationship. To address this, we examined dimensional changes in dentin subjected to cyclic fatigue in two different pH environments. Human dentin cantilever-beams were fatigued under load control in pH = 6 (n = 13) or pH = 7 (n = 13) buffer, with a load ratio (R = minimum load/maximum load) of 0.1 and frequency of 2 Hz, and stresses between 5.5 and 55 MPa. Material loss was measured at high- and low-stress locations before and after cycling. Of the 23 beams, 7 withstood 1,000,000 cycles; others cracked earlier. Mean material loss in high-stress areas was greater than in low-stress areas, and losses were greater at pH = 6 than at pH = 7, suggesting that mechanical stress and lower pH both accelerate erosion of dentin surfaces.

  16. Calcium transport in the rabbit superficial proximal convoluted tubule

    SciTech Connect

    Ng, R.C.; Rouse, D.; Suki, W.N.

    1984-09-01

    Calcium transport was studied in isolated S2 segments of rabbit superficial proximal convoluted tubules. 45Ca was added to the perfusate for measurement of lumen-to-bath flux (JlbCa), to the bath for bath-to-lumen flux (JblCa), and to both perfusate and bath for net flux (JnetCa). In these studies, the perfusate consisted of an equilibrium solution that was designed to minimize water flux or electrochemical potential differences (PD). Under these conditions, JlbCa (9.1 +/- 1.0 peq/mm X min) was not different from JblCa (7.3 +/- 1.3 peq/mm X min), and JnetCa was not different from zero, which suggests that calcium transport in the superficial proximal convoluted tubule is due primarily to passive transport. The efflux coefficient was 9.5 +/- 1.2 X 10(-5) cm/s, which was not significantly different from the influx coefficient, 7.0 +/- 1.3 X 10(-5) cm/s. When the PD was made positive or negative with use of different perfusates, net calcium absorption or secretion was demonstrated, respectively, which supports a major role for passive transport. These results indicate that in the superficial proximal convoluted tubule of the rabbit, passive driving forces are the major determinants of calcium transport.

  17. Malpighian tubule development in the red flour beetle (Tribolium castaneum).

    PubMed

    King, Benedict; Denholm, Barry

    2014-11-01

    Malpighian tubules (MpTs) are the major organ for excretion and osmoregulation in most insects. MpT development is characterised for Drosophila melanogaster, but not other species. We therefore do not know the extent to which the MpT developmental programme is conserved across insects. To redress this we provide a comprehensive description of MpT development in the beetle Tribolium castaneum (Coleoptera), a species separated from Drosophila by >315 million years. We identify similarities with Drosophila MpT development including: 1) the onset of morphological development, beginning when tubules bud from the gut and proliferate to increase organ size. 2) the tubule is shaped by convergent-extension movements and oriented cell divisions. 3) differentiated tip cells activate EGF-signalling in distal MpT cells through the ligand Spitz. 4) MpTs contain two main cell types - principal and stellate cells, differing in morphology and gene expression. We also describe development of the beetle cryptonephridial system, an adaptation for water conservation, which represents a major modification of the MpT ground plan characterised by intimate association between MpTs and rectum. This work establishes a new model to compare MpT development across insects, and provides a framework to help understand how an evolutionary novelty - the cryptonephridial system - arose during organ evolution.

  18. Effect of self-etching primer vs phosphoric acid etchant on bonding to bur-prepared dentin.

    PubMed

    Ogata, M; Harada, N; Yamaguchi, S; Nakajima, M; Tagami, J

    2002-01-01

    This study evaluated the effect of dentin conditioner on tensile bond strength to dentin prepared with different types of burs. A self-etching primer system, Mac-Bond II (MB, Tokuyama Dental) and a phosphoric acid etching system, Single Bond (SB, 3M) were used for conditioning. Twenty-four extracted intact human molars were ground flat to expose occlusal dentin. After the dentin surfaces were polished with #600 SiC paper, the teeth were randomly divided into a control group and three experimental groups according to the bur grits used: #600 SiC paper only as the control, fine cut steel bur (SB600), crosscut steel bur (SB703) and regular grit diamond bur (DB) mounted in a dental handpiece utilizing water cooling. The dentin surfaces were treated with one of two adhesive systems, then composite buildups were done with Clearfil AP-X (Kuraray Medical). After soaking the bond specimens for 24 hours in 37 degrees C water, multiple vertical serial sections (0.7 mm thick, 7-8 slices per one tooth) were made, trimmed to form an hour-glass shape with a 1.0 mm2 cross-section and tensile bond strengths were determined at a crosshead speed of 1 mm/minute. Statistical analysis was made using one and two-way ANOVA and Fisher's PLSD test (p<0.05). Six additional molars were used for SEM observations of the dentin surfaces of each group before and after treatment with the self-etching primer of MB, and another four teeth were used to observe the resin-dentin interface of each group of SB. Using MB, the DB group produced the lowest tensile bond strength (TBS) among the groups that received bur preparation, and there were no statistical differences among SB600, SB703 and the control. For SB, the TBS of SB703 was the highest, and there were no statistical differences among the other groups and the control. The influence of the method used to prepare dentin for micro-tensile bond strength testing was dependent on the adhesive system used.

  19. The effect of exercise training on transverse tubules in normal, remodeled, and reverse remodeled hearts.

    PubMed

    Kemi, Ole J; Hoydal, Morten A; Macquaide, Niall; Haram, Per M; Koch, Lauren G; Britton, Steven L; Ellingsen, Oyvind; Smith, Godfrey L; Wisloff, Ulrik

    2011-09-01

    The response of transverse (T)-tubules to exercise training in health and disease remains unclear. Therefore, we studied the effect of exercise training on the density and spacing of left ventricle cardiomyocyte T-tubules in normal and remodeled hearts that associate with detubulation, by confocal laser scanning microscopy. First, exercise training in normal rats increased cardiomyocyte volume by 16% (P < 0.01), with preserved T-tubule density. Thus, the T-tubules adapted to the physiologic hypertrophy. Next, we studied T-tubules in a rat model of metabolic syndrome with pressure overload-induced concentric left ventricle hypertrophy, evidenced by 15% (P < 0.01) increased cardiomyocyte size. These rats had only 85% (P < 0.01) of the T-tubule density of control rats. Exercise training further increased cardiomyocyte volume by 8% (P < 0.01); half to that in control rats, but the T-tubule density remained unchanged. Finally, post-myocardial infarction heart failure induced severe cardiac pathology, with a 70% (P < 0.01) increased cardiomyocyte volume that included both eccentric and concentric hypertrophy and 55% (P < 0.01) reduced T-tubule density. Exercise training reversed 50% (P < 0.01) of the pathologic hypertrophy, whereas the T-tubule density increased by 40% (P < 0.05) compared to sedentary heart failure, but remained at 60% of normal hearts (P < 0.01). Physiologic hypertrophy associated with conserved T-tubule spacing (~1.8-1.9 µm), whereas in pathologic hypertrophy, T-tubules appeared disorganized without regular spacing. In conclusion, cardiomyocytes maintain the relative T-tubule density during physiologic hypertrophy and after mild concentric pathologic hypertrophy, whereas after severe pathologic remodeling with a substantial loss of T-tubules; exercise training reverses the remodeling and partly corrects the T-tubule density.

  20. Bovine dentine organic matrix down-regulates osteoclast activity.

    PubMed

    Sriarj, Wantida; Aoki, Kazuhiro; Ohya, Keiichi; Takagi, Yuzo; Shimokawa, Hitoyata

    2009-01-01

    Physiological root resorption is a phenomenon that normally takes place in deciduous teeth; root resorption of permanent teeth occurs only under pathological conditions. The molecular mechanisms underlying these processes are still unclear. Our previous study showed that osteoclasts cultured on deciduous dentine exhibited a higher degree of resorption and higher levels of cathepsin K and MMP-9 mRNA than osteoclasts cultured on permanent dentine. These results could be because of different susceptibilities to acid and the different organic matrices between deciduous and permanent dentine. Thus, the purpose of this study was to investigate the effect of dentine extracts from bovine deciduous and permanent dentine on osteoclast activity. Osteoclasts, obtained from mouse bone marrow cells co-cultured with an osteoblast-rich fraction in the presence of 1,25-(OH)(2)-vitamin D3 and PGE2, were incubated with or without 0.6 M HCl extracts from bovine deciduous or permanent dentine for 48 h. TRAP positive cell number, TRAP activity, the areas of resorption pits, and mRNA levels of TRAP, v-ATPase, calcitonin receptor, cathepsin K, and MMP-9 were examined. The results illustrated that TRAP activity, the resorbed area, and the mRNA levels of osteoclast marker genes seemed to be suppressed by both deciduous and permanent dentine extracts. These findings indicate that some factors that suppress osteoclast activity are contained in both deciduous and permanent dentine extracts. Although there was no significant difference in osteoclast activity between deciduous and permanent dentine extracts, osteoclasts incubated with permanent dentine extracts tend to exhibit less resorption activity than those incubated with deciduous dentine extracts. However, we could not clearly explain the causes of this.

  1. Shear bond strength of bulk-fill and nano-restorative materials to dentin

    PubMed Central

    Colak, Hakan; Ercan, Ertugrul; Hamidi, Mehmet Mustafa

    2016-01-01

    Objectives: Bulk-fill composite materials are being developed for preparation depths of up to 4 mm in an effort to simplify and improve the placement of direct composite posterior restorations. The aim of our study was to compare shear-bond strength of bulk-fill and conventional posterior composite resins. Materials and Methods: In this study, 60 caries free extracted human molars were used and sectioned parallel to occlusal surface to expose midcoronal dentin. The specimens were randomly divided into four groups. Total-etch dentine bonding system (Adper Scotchbond 1XT, 3M ESPE) was applied to dentin surface in all the groups to reduce variability in results. Then, dentine surfaces covered by following materials. Group I: SonicFill Bulk-Fill, Group II: Tetric EvoCeram (TBF), Group III: Herculite XRV Ultra, and Group IV: TBF Bulk-Fill, 2 mm × 3 mm cylindrical restorations were prepared by using application apparatus. Shear bond testing was measured by using a universal testing machine. Kruskal–Wallis and Mann–Whitney U-tests were performed to evaluate the data. Results: The highest value was observed in Group III (14.42 ± 4.34) and the lowest value was observed in Group IV (11.16 ± 2.76) and there is a statistically significant difference between these groups (P = 0.046). However, there is no statistically significant difference between the values of other groups. In this study, Group III was showed higher strength values. Conclusion: There is a need for future studies about long-term bond strength and clinical success of these adhesive and bulk-fill systems. PMID:27011738

  2. Hybridization quality and bond strength of adhesive systems according to interaction with dentin

    PubMed Central

    Salvio, Luciana Andrea; Hipólito, Vinicius Di; Martins, Adriano Luis; de Goes, Mario Fernando

    2013-01-01

    Objective: To evaluate the hybridization quality and bond strength of adhesives to dentin. Materials and Methods: Ten human molars were ground to expose the dentin and then sectioned in four tooth-quarters. They were randomly divided into 5 groups according to the adhesive used: Two single-step self-etch adhesives – Adper Prompt (ADP) and Xeno III (XE), two two-step self-etching primer systems – Clearfil SE Bond (SE) and Adhe SE (ADSE), and one one-step etch-and-rinse system – Adper Single Bond (SB). Resin composite (Filtek Z250) crown buildups were made on the bonded surfaces and incrementally light-cured for 20 s. The restored tooth-quarters were stored in water at 37°C for 24 h and then sectioned into beams (0.8 mm2 in cross-section). Maximal microtensile bond strength (μ-TBS) was recorded (0.5 mm/min in crosshead speed). The results were submitted to one-way ANOVA and Tukey's test (α = 0.05). Thirty additional teeth were used to investigate the hybridization quality by SEM using silver methenamine or ammoniacal silver nitrate dyes. Results: SE reached significantly higher μ-TBS (P < 0.05); no significance was found between ADSE and XE (P > 0.05), and between SB and ADP (P > 0.05); ADSE and XE were significantly higher than SB and ADP (P < 0.05). The bonding interface of SB showed the most intense silver uptake. SE and ADSE showed more favorable hybridization quality than that observed for ADP and XE. Conclusions: The bond strength and hybridization quality were affected by the interaction form of the adhesives with dentin. The hybridization quality was essential to improve the immediate μ-TBS to dentin. PMID:24926212

  3. A new improved protocol for in vitro intratubular dentinal bacterial contamination for antimicrobial endodontic tests: standardization and validation by confocal laser scanning microscopy

    PubMed Central

    de ANDRADE, Flaviana Bombarda; ARIAS, Marcela Paola Castro; MALIZA, Amanda Garcia Alves; DUARTE, Marco Antonio Hungaro; GRAEFF, Márcia Sirlene Zardin; AMOROSO-SILVA, Pablo Andrés; MIDENA, Raquel Zanin; de MORAES, Ivaldo Gomes

    2015-01-01

    Objectives To compare three methods of intratubular contamination that simulate endodontic infections using confocal laser scanning microscopy (CLSM). Material and Methods Two pre-existing models of dentinal contamination were used to induce intratubular infection (groups A and B). These methods were modified in an attempt to improve the model (group C). Among the modifications it may be included: specimen contamination for five days, ultrasonic bath with BHI broth after specimen sterilization, use of E. faecalis during the exponential growth phase, greater concentration of inoculum, and two cycles of centrifugation on alternate days with changes of culture media. All specimens were longitudinally sectioned and stained with of LIVE/DEAD® for 20 min. Specimens were assessed using CLSM, which provided images of the depth of viable bacterial proliferation inside the dentinal tubules. Additionally, three examiners used scores to classify the CLSM images according to the following parameters: homogeneity, density, and depth of the bacterial contamination inside the dentinal tubules. Kruskal-Wallis and Dunn’s tests were used to evaluate the live and dead cells rates, and the scores obtained. Results The contamination scores revealed higher contamination levels in group C when compared with groups A and B (p<0.05). No differences were observed between group A and B (p>0.05). The volume of live cells in group C was higher than in groups A and B (p<0.05). Conclusion The new protocol for intratubular infection resulted in high and uniform patterns of bacterial contamination and higher cell viability in all specimens when compared with the current methods. PMID:26200524

  4. Zinc induces apatite and scholzite formation during dentin remineralization.

    PubMed

    Osorio, R; Osorio, E; Cabello, I; Toledano, M

    2014-01-01

    The aim of this study was to ascertain whether zinc may improve the repair ability of demineralized dentin. Dentin disks were demineralized by phosphoric acid during 15 s and immersed in artificial saliva, remineralizing solution, a zinc chloride solution and a zinc oxide solution. Dentin specimens were analyzed after 24 h and 1 month of storage. Surface morphology was assessed by atomic force and scanning electron microscopy, mechanical properties were analyzed by nanohardness testing in a TriboIndenter, and chemical changes at the surfaces were determined by X-ray diffraction, Raman and energy-dispersive elemental analyses. After phosphoric acid application, dentin was only partially demineralized. Demineralized dentin was remineralized after 24 h of storage in any of the tested solutions (nanohardness increased and hydroxylapatite formation was detected by Raman). Remineralization was maintained up to 1 month in dentin stored in remineralizing solution, zinc chloride and zinc oxide. Zinc and phosphate were important for hydroxylapatite homeostasis. Scholzite formation was encountered in dentin stored in zinc-containing solutions. Zinc might allow to reach the balance between dentin demineralization and remineralization processes.

  5. 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

  6. Effect of Fluoride Varnish Combined with Er:YAG Laser on the Permeability of Eroded Dentin: An In Situ Study.

    PubMed

    Nemezio, Mariana Alencar; Carvalho, Sandra Chiga; Scatolin, Renata Siqueira; Colucci, Vivian; Galo, Rodrigo; Corona, Silmara Aparecida Milori

    2015-01-01

    This study evaluated the combined effect of fluoride varnish and Er:YAG laser on the permeability of eroded bovine root dentin. After initial erosive challenge followed by a remineralization period, the specimens were divided in two groups according to the treatment - fluoride varnish and non-fluoride varnish - and were subdivided according to the irradiation protocol: Er:YAG laser (100 mJ, 3 Hz, 12.8 J/cm2per pulse, non-contact and defocus mode) and non-irradiated. After a lead-in period, 7 volunteers wore a palatal device containing 4 specimens that were subjected to erosive challenges. At the first experimental phase, 4 volunteers used specimens treated with fluoride varnish and fluoride varnish+Er:YAG laser and 3 volunteers used specimens treated with non-fluoride varnish and non-fluoride varnish+Er:YAG laser. After a washout period, volunteers were crossed to treatments, characterizing a 2x2 crossover experiment. At the end of the experimental phase, the quantitative response variable was obtained by permeability analysis and the qualitative response by scanning electron microscopy (SEM). Two-way ANOVA and Tukey-Kramer's test revealed that specimens treated with fluoride varnish+Er:YAG laser showed the lowest permeability and a significant difference was found between this group and the others. When varnish (fluoride/non-fluoride) was applied in the absence of Er:YAG laser, higher permeability was found when compared to the laser-treated groups. SEM evaluations showed partially or completely obliterated dentinal tubules when specimens were treated with fluoride varnish+Er:YAG laser. It may be concluded that Er:YAG laser was able to control the permeability of eroded root dentin and the combination with fluoride varnish increased laser action.

  7. Intracellular Na+ and K+ activities and membrane conductances in the collecting tubule of Amphiuma

    PubMed Central

    1988-01-01

    Membrane potentials and conductances, and intracellular ionic activities were studied in isolated perfused collecting tubules of K+- adapted Amphiuma. Intracellular Na+ (aNai) and K+ (aKi) activities were measured, using liquid ion-exchanger double-barreled microelectrodes. Apical and basolateral membrane conductances were estimated by cable analysis. The effects of inhibition of the apical conductance by amiloride (10(-5) M) and of inhibition of the basolateral Na-K pump by either a low K+ (0.1 mM) bath or by ouabain (10(-4) M) were studied. Under control conditions, aNai was 8.4 +/- 1.9 mM and aKi 56 +/- 3 mM. With luminal amiloride, aNai decreased to 2.2 +/- 0.4 mM and aKi increased to 66 +/- 3 mM. Ouabain produced an increase of aNai to 44 +/- 4 mM, and a decrease of aKi to 22 +/- 6, and similar changes were observed when the tubule was exposed to a low K+ bath solution. During pump inhibition, there was a progressive decrease of the K+-selective basolateral membrane conductance and of the Na+ permeability of the apical membrane. A similar inhibition of both membrane conductances was observed after pump inhibition by low K+ solution. Upon reintroduction of K+, a basolateral membrane hyperpolarization of -23 +/- 4 mV was observed, indicating an immediate reactivation of the electrogenic Na-K pump. However, the recovery of the membrane conductances occurred over a slower time course. These data imply that both membrane conductances are regulated according to the intracellular ionic composition, but that the basolateral K+ conductance is not directly linked to the pump activity. PMID:3235975

  8. Dentin permeability. Effects of desensitizing dentifrices in vitro.

    PubMed

    Pashley, D H; O'Meara, J A; Kepler, E E; Galloway, S E; Thompson, S M; Stewart, F P

    1984-09-01

    Patients using placebo dentifrices in clinical trials usually show a significant decrease in dentin sensitivity over a 2- to 4-week period. If their sensitivity were due to hydrodynamic fluid movement, then the results suggest that there was a decrease in their dentin permeability. This hypothesis was tested in vitro by measuring the ease with which fluid could flow (i.e., hydraulic conductance) across dentin discs before and after brushing the discs with a variety of dentifrices, including most of the marketed densensitizing dentifrices. All dentifrices decreased the hydraulic conductance of dentin. An experimental dentifrice containing oxalate as the active ingredient was far more effective than any of the marketed dentifrices. The results tend to support the hypothesis that, at least part of the reduction in clinical sensitivity in patients with hypersensitive dentin is due to the abrasive action of the dentifrice.

  9. 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.

  10. 2,3,7,8-Tetrachlorodibenzo-p-dioxin specifically reduces mRNA for the mineralization-related dentin sialophosphoprotein in cultured mouse embryonic molar teeth

    SciTech Connect

    Kiukkonen, Anu . E-mail: Anu.Kiukkonen@helsinki.fi; Sahlberg, Carin; Lukinmaa, Pirjo-Liisa; Alaluusua, Satu; Peltonen, Eija; Partanen, Anna-Maija

    2006-11-01

    Previous studies show that the most toxic dioxin congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), interferes with mineralization of the dental matrices in developing mouse and rat teeth. Culture of mouse embryonic molar teeth with TCDD leads to the failure of enamel to be deposited and dentin to undergo mineralization. Lactationally exposed rats show defectively matured enamel and retardation of dentin mineralization. To see if the impaired mineralization is associated with changes in the expression of dentin sialophosphoprotein (Dspp), Bono1 and/or matrix metalloproteinase-20 (MMP-20), thought to be involved in mineralization of the dental hard tissues, we cultured mouse (NMRI) E18 mandibular molars for 3, 5 or 7 days and exposed them to 1 {mu}M TCDD after 2 days of culture. As detected by in situ hybridization of tissue sections, localization and intensity of Bono1 and MMP-20 expression showed no definite difference between the control and exposed tooth explants, suggesting that TCDD does not affect their expression. On the contrary, TCDD reduced or prevented the expression of Dspp in secretory odontoblasts and decreased it in presecretory ameloblasts. The results suggest that the retardation of dentin mineralization by TCDD in mouse molar teeth involves specific interference with Dspp expression.

  11. Effect of Non-Thermal Argon Plasma on Bond Strength of a Self-Etch Adhesive System to NaOCl-Treated Dentin.

    PubMed

    Abreu, João Luiz Bittencourt de; Prado, Maíra; Simão, Renata Antoun; Silva, Eduardo Moreira da; Dias, Katia Regina Hostilio Cervantes

    2016-01-01

    Studies have been showing a decrease of bond strength in dentin treated with sodium hypochlorite (NaOCl). The aim of this study was to evaluate the effect of non-thermal argon plasma on the bond strength of a self-etch adhesive system to dentin exposed to NaOCl. Thirty-two flat dentin surfaces of bovine incisors were immersed in 2.5% NaOCl for 30 min to simulate the irrigation step during endodontic treatment. The specimens were divided into four groups (n=8), according to the surface treatment: Control (without plasma treatment), AR15 (argon plasma for 15 s), AR30 (argon plasma for 30 s) and AR45 (argon plasma for 45 s). For microtensile bond strength test, 5 specimens were used per group. In each group, the specimens were hybridized with a self-etch adhesive system (Clearfil SE Bond) and resin composite buildups were constructed. After 48 h of water storage, specimens were sectioned into sticks (5 per tooth, 25 per group) and subjected to microtensile bond strength test (μTBS) until failure, evaluating failure mode. Three specimens per group were analyzed under FTIR spectroscopy to verify the chemical modifications produced in dentin. μTBS data were analyzed using ANOVA and Tamhane tests (p<0.05). AR30 showed the highest μTBS (20.86±9.0). AR15 (13.81±6.4) and AR45 (11.51±6.8) were statistically similar to control (13.67±8.1). FTIR spectroscopy showed that argon plasma treatment produced chemical modifications in dentin. In conclusion, non-thermal argon plasma treatment for 30 s produced chemical changes in dentin and improved the μTBs of Clearfil SE Bond to NaOCl-treated dentin.

  12. Influence of Nonenzymatic Glycation in Dentinal Collagen on Dental Caries.

    PubMed

    Matsuda, Y; Miura, J; Shimizu, M; Aoki, T; Kubo, M; Fukushima, S; Hashimoto, M; Takeshige, F; Araki, T

    2016-12-01

    Advanced glycation end-products (AGEs) are generated via nonenzymatic glycation of dentinal collagen, resulting in accumulation of AGEs in dentin tissue. Since accumulated AGEs cause crosslinking between amino acid polypeptides in the collagen molecule and modify mechanical properties of dentinal collagen, the authors assumed that there would be a significant interaction between the generation of AGEs and progression of caries in dentin. To confirm such an interaction, spectroscopic imaging analyses (i.e., nanosecond fluorescence lifetime imaging and second harmonic generation light imaging) were performed in addition to biochemical and electron microscopic analyses in the present study. Seven carious human teeth were fixed in paraformaldehyde and cut longitudinally into 1-mm sections using a low-speed diamond saw for the following analyses. In transmission electron microscopy (TEM) analysis, nondecalcified specimens were embedded in epoxy resin and sliced into thin sections for observation. For the immunohistochemical analysis, the specimens were paraffin embedded after decalcification for 2 wk and sectioned with a microtome. Resultant sections were stained with anti-AGE and anticollagen antibodies. The demineralized specimens were used for spectroscopic analyses without additional treatment. For Western blotting analysis, specimens were separated into carious and sound dentin. Each specimen was homogenized with a bead crusher and an ultrasonic homogenizer and then treated with hydrochloric acid. In carious dentin, the collagen fibers showed an amorphous structure in the TEM image, and the AGEs were localized in the areas of bacterial invasion in the immunostaining image. The total amount of AGEs in carious dentin was higher than in sound dentin in Western blotting. The ultrastructure of type I collagen and total amount of AGEs varied markedly in the dentinal caries region. The fluorescence lifetime was shorter in the carious area than that in the sound areas

  13. 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

  14. How to increase the durability of resin-dentin bonds.

    PubMed

    Pashley, David H; Tay, Franklin R; Imazato, Satoshi

    2011-09-01

    Resin-dentin bonds are not as durable as was previously thought. Microtensile bond strengths often fall 30% to 40% in 6 to 12 months. The cause of this poor durability is a combination of the activation of matrix metalloproteinases (MMPs) by weak acids such as lactic acid released by caries-producing bacteria, and acid-etchants used in adhesive bonding systems. These acids uncover and activate matrix-bound MMPs. The other contributing factor is incomplete resin infiltration. If all exposed collagen fibrils were enveloped by resin, the MMPs would not have free access to water, an obligatory requirement of these enzymes. Recently, several inhibitors of MMPs have been added to adhesive primers. Examples include chlorhexidine (CHX), benzalkonium chloride (BAC), and MDPB, an antibacterial monomer used in a two-step self-etching primer adhesive. The advantage of MDPB over CHX and BAC is that it polymerizes with adhesive resins and cannot leach from the hybrid layer. This is an example of what can be termed a "therapeutic adhesive system" that provides anti-MMP activity along with antibacterial qualities.

  15. The dynamin superfamily: universal membrane tubulation and fission molecules?

    PubMed

    Praefcke, Gerrit J K; McMahon, Harvey T

    2004-02-01

    Dynamins are large GTPases that belong to a protein superfamily that, in eukaryotic cells, includes classical dynamins, dynamin-like proteins, OPA1, Mx proteins, mitofusins and guanylate-binding proteins/atlastins. They are involved in many processes including budding of transport vesicles, division of organelles, cytokinesis and pathogen resistance. With sequenced genomes from Homo sapiens, Drosophila melanogaster, Caenorhabditis elegans, yeast species and Arabidopsis thaliana, we now have a complete picture of the members of the dynamin superfamily from different organisms. Here, we review the superfamily of dynamins and their related proteins, and propose that a common mechanism leading to membrane tubulation and/or fission could encompass their many varied functions.

  16. Cyclic testing of porcelain laminiate veneers on superficial enamel and dentin: Pressed vs. conventional layered porcelain

    NASA Astrophysics Data System (ADS)

    Tawde, Shweta

    Statement of Problem: Clinicians are inclined towards more aggressive teeth preparations to accommodate the thickness of the veneering material. The principle of conservative tooth preparation is compromised. Purpose: By using a conservative approach to treatment with porcelain veneers, long-lasting, esthetic and functional results may be achieved. Sacrificing as little tooth structure as possible and conserving the supporting tissues will facilitate prospective patients. Materials and Methods: Forty extracted human maxillary and mandibular canines were selected. The teeth were divided into one of two groups (pressable and stackable) and further subdivided according to tooth substrate (all-enamel or mixed enamel-dentin exposure). Twenty canine teeth were allotted to the pressable veneer group and 20 were allotted to the stackable veneer group. Of the 20 teeth in the pressable group, all were pressed with a lithium disilicate ceramic system (IPS e.max Press), 10 with labial tooth reduction of 0.3-0.5 mm maintaining superficial enamel (PEN) and the remaining 10 teeth with labial veneer reduction of 0.8-1.0 mm exposing superficial dentin (PDN). Of the 20 teeth in the stackable group, all were stacked/ layered with conventional feldspathic porcelain (Fortune; Williams/ Ivoclar); with labial veneer reduction of 0.3-0.5 mm maintaining superficial enamel (SEN) and the remaining 10 teeth with labial veneer reduction of 0.8-1.0 mm exposing superficial dentin (SDN). Silicon putty matrix was fabricated prior to teeth preparation to estimate the teeth reduction. The prepared facial reduction was limited to the incisal edge. No incisal or palatal/lingual reduction was performed. Impressions of the prepared teeth were taken in medium/light-bodied PVS. Master casts were made in Resin Rock. The stackable group specimens were made with fabricating refractory dies and after following the recommended steps of laboratory procedure, stackable veneers were processed. The pressable group

  17. The influence of the lining material on the repair of the infected dentin in young permanent molars after restoration: A randomized clinical trial

    PubMed Central

    Kuhn, Eunice; Reis, Alessandra; Chibinski, Ana Claudia Rodrigues; Wambier, Denise Stadler

    2016-01-01

    Aim: This study evaluated the impact of liner material on the fluorescence, morphological and mineral characteristics of permanent carious dentin after cavity sealing. Methods: Thirty children (11.0 ± 2.7 years old) presenting at least one active deep carious lesion in permanent molars were selected. Fragments of carious dentin were removed from teeth before lining the cavity (baseline samples) with high-viscosity glass ionomer cement (G1) or an inert material (wax - G2). Cavities were restored with composite resin and reopened 60 days later, and other fragments were removed (60-day sample). The laser fluorescence (LF) readings and morphological and mineral changes of both groups were compared. Results: After 60 days, forty teeth were available for evaluation. Lower LF means were obtained (Wilcoxon signed-rank test; P < 0.05), and enhanced calcium and phosphorus levels were detected for both groups (t-test, P < 0.05). An uptake of fluorine was observed only in G1 (t-test; P < 0.05). Regardless of the group, baseline samples exhibited clear signs of bacterial invasion, and the collagen fibers were exposed; the 60-day samples showed a better-organized tissue with a more compact intertubular dentin. Conclusion: Caries arrestment with dentin reorganization occurs regardless of the lining material placed in contact with the infected dentin. PMID:27994311

  18. Micro-tensile bond strength of different adhesive systems on sound dentin and resin-based composite: An in-vitro study

    PubMed Central

    Mallick, Rashmirekha; Sarangi, Priyanka; Mohanty, Sandhyarani; Behera, Subasish; Nanda, Soumyaranjan; Satapathy, Sukanta Kumar

    2015-01-01

    Aim: To analyze the difference in the micro-tensile bond strength of specimens made with two different adhesive systems and compare them with two homogenous substrates. Materials and Methods: Sixty permanent mandibular molars were mounted in acrylic blocks and sectioned with exposed dentin surfaces. Samples were then divided into four groups. To Group-I Adper Single Bond 2 and to Group-II Adper Self-Etch plus bonding agents were applied. For Group-I and Group-II beams consisted of resin composite in the upper half and dentin in the lower half. In Group-III beams were made of only dentin. In Group-IV beams were made of only composite. Fifteen specimens of each group were taken for the micro-tensile bond strength test. Statistical Analysis: The results are analyzed using one-way analysis of variance and Critical Difference test. Results: The interface bonded with the two adhesive systems had lower micro-tensile bond strength than those of dentin and resin composite and the self-etching adhesive Adper Self-Etch plus had comparable bond strength with total-etch adhesive Adper Single Bond 2. Conclusion: The bond strength values for current adhesive systems cannot be compared to the micro-tensile bond strength of dentin and resin composite, and self-etching adhesives have comparable bond strength with total-etch adhesives. PMID:26430301

  19. Effect of titanium dioxide and 3.5% hydrogen peroxide with 405-nm diode laser irradiation on bonding of resin to pulp chamber dentin

    NASA Astrophysics Data System (ADS)

    Haruyama, A.; Kato, J.; Kameyama, A.; Hirai, Y.; Oda, Y.

    2010-04-01

    This study was conducted to determine the effect of a 3.5% hydrogen peroxide solution containing titanium dioxide on bonding of resin to pulp chamber dentin. Extracted bovine anterior teeth were allocated to three groups of ten teeth each. The coronal labial pulp chamber dentin was exposed and bleached with 3.5% hydrogen peroxide with titanium dioxide with 405-nm diode laser irradiation for 15 min (Group 1); 30% hydrogen peroxide with halogen lamp irradiation for 15 min (Group 2); and distilled water for 15 min (Group 3). After bleaching, the pulp chamber dentin was prepared for composite resin bonding and the interface between the resin and dentin was observed by scanning electron microscopy. The microtensile bond strength (μTBS) and failure patterns were determined. The μTBS values (mean ± SD) were: 17.28 ± 5.79 MPa ( n = 36), 0 MPa, and 26.50 ± 9.83 MPa ( n = 36) in Groups 1, 2, and 3, respectively. The μTBS in Group 3 was significantly higher than that in Group 1 ( P < 0.05). Hybrid layers and resin tags were clearly observed at the interface in Groups 1 and 3, but not in Group 2. Adhesive failure was mainly observed in Group 1, whereas dentin failure was the main failure pattern in Group 3.

  20. Collagen Cross-linking Increases Its Biodegradation Resistance in Wet Dentin Bonding

    PubMed Central

    Xu, Changqi; Wang, Yong

    2014-01-01

    Purpose The biodegradation of exposed dentin collagen within the adhesive/dentin (a/d) interface is one of main reasons leading to composite restoration failures and seriously affects the durability of dental restorations. In the present study, the objective was to investigate whether the inclusion of the crosslinking reagent (glutaraldehyde, GA) in the adhesive would increase collagen biodegradation resistance within the a/d interface. Materials and methods The model adhesive consisted of ~60 % monomers (HEMA/BisGMA, 45/55 wt/wt) and ~ 40 % ethanol as a solvent. 5% GA was added to the above formulation. After the dentin surfaces were etched for 15 s with 35% phosphoric acid, rinsed with water and blotted dry, adhesives both with and without GA were applied and polymerized by visible light for 20 s. These a/d specimens were immersed in the biodegradation solution (prepared by adding 160 mg collagenase in 1 liter of TESCA buffer solution) for up to 30 days after proceeding with the sectioning/fracture to expose the a/d interfaces. The specimens were analyzed using SEM and micro-Raman. Results SEM results indicated that for the adhesive without GA, there were many voids and was a loss of collagen fibrils in the a/d interface after being challenged by the biodegradation solution. The Raman spectra collected from the interface showed that the amide I of collagen at 1667 cm−1 obviously decreased, indicating a removal of collagen fibrils during the degradation process. For the adhesive containing GA, the collagen fibrils within the interface did not degrade at all, which was also confirmed by the Raman results. Conclusion The results corroborate the previous findings that by using the current adhesive system and wet bonding, the collagen fibrils in the a/d interface are largely unprotected and easily undergo biodegradation. Directly including crosslinking agents in the adhesive could protect collagen fibrils from degradation in situ within the a/d interface. PMID

  1. Efficacy of various cleansing techniques on dentin wettability and its influence on shear bond strength of a resin luting agent

    PubMed Central

    Mohanaj, Dhivya; Beganam, Mohammed

    2012-01-01

    PURPOSE To evaluate the shear bond strength of resin luting agent to dentin surfaces cleansed with different agents like pumice, ultrasonic scaler with chlorhexidine gluconate, EDTA and the influence of these cleansing methods on wetting properties of the dentin by Axisymmetric drop Shape Analysis - Contact Diameter technique (ADSA-CD). MATERIALS AND METHODS Forty coronal portions of human third molar were prepared until dentin was exposed. Specimens were divided into two groups: Group A and Group B. Provisional restorations made with autopolymerizing resin were luted to dentin surface with zinc oxide eugenol in Group A and with freegenol cement in Group B. All specimens were stored in distilled water at room temperature for 24 hrs and provisional cements were mechanically removed with explorer and rinsed with water and cleansed using various methods (Control-air-water spray, Pumice prophylaxis, Ultrasonic scaler with 0.2% Chlorhexidine gluconate, 17% EDTA). Contact angle measurements were performed to assess wettability of various cleansing agents using the ADSA-CD technique. Bond strength of a resin luting agent bonded to the cleansed surface was assessed using Instron testing machine and the mode of failure noted. SEM was done to assess the surface cleanliness. Data were statistically analyzed by one-way analysis of variance with Tukey HSD tests (α=.05). RESULTS Specimens treated with EDTA showed the highest shear bond strength and the lowest contact angle for both groups. SEM showed that EDTA was the most effective solution to remove the smear layer. Also, mode of failure seen was predominantly cohesive for both EDTA and pumice prophylaxis. CONCLUSION EDTA was the most effective dentin cleansing agent among the compared groups. PMID:22977721

  2. Shear bond strength of Dyract compomer material to dentin of primary molars.

    PubMed

    Megid, F Y; Salama, F S

    1997-01-01

    The purpose of this study was to measure and compare the shear bond strength and fracture pattern of Dyract compomer material with and without use of PSA prime/adhesive as well as 35% phosphoric acid etching to the buccal dentin of primary first and second molars. In addition, micromorphology of the restorative surfaces opposing the tooth structure following these different surface treatments was evaluated. For shear bond strength measurement and fracture pattern evaluation, 36 extracted non-restored human primary molars with mild to moderate caries divided into 3 groups of 12 teeth each were used. Dyract with and without use of PSA prime/adhesive as well as 35% phosphoric acid etching for 15 seconds prior to placement of PSA prime/adhesive was applied to the buccal surface of exposed dentin. A standardized tube of Dyract was placed on each dentin surface and polymerized. The tubes were sheared off with a Universal testing machine at a cross head speed of 12.7 mm/min. For evaluation of the restorative surfaces opposing the tooth structure, 9 teeth divided into 3 groups of 3 teeth each were used to prepare the specimens, which were then demineralized in 10% hydrochloric acid for 24 hours. Fitting surfaces of these specimens were prepared and examined using scanning electron microscope. Tukey's multiple range test showed that the shear bond strength of Dyract with PSA prime/adhesive (group 1) was statistically significantly higher than Dyract without PSA prime/adhesive (group 2) and phosphoric acid etching (group 3). The shear bond strength in group 1 averaged 5.89 +/- 1.40 (X + SD MPa) while for groups 2 and averaged 1.49 +/- 0.69 and 3.69 +/- 0.89 respectively. Pretreatment of dentin surface with 35% phosphoric acid increased resin tags formation but it did significantly lower shear bond strength of Dyract with PSA prime/adhesive to dentin of primary molars. Bond failure patterns for all groups were only adhesive and mixed type failures.

  3. Pulsed HF laser ablation of dentin

    NASA Astrophysics Data System (ADS)

    Papagiakoumou, Eirini I.; Papadopoulos, Dimitris N.; Makropoulou, Mersini I.; Khabbaz, Maruan G.; Serafetinides, Alexander A.

    2005-03-01

    The interaction of a TEA (Transversally Excited Atmospheric pressure) corona preionized oscillator double amplifier HF (hydrogen fluoride) laser beam with dentin tissue is reported. Pulses of 39 ns in the wavelength range of 2.65-3.35 μm and output energies in the range of 10-45 mJ, in a predominantly TEM00 beam were used to interact with dentin tissue. Ablation experiments were conducted with the laser beam directly focused on the tissue. Several samples of freshly extracted human teeth were used, cut longitudinally in facets of about 1mm thick and stored in phosphate buffered saline after being cleaned from the soft tissue remains. The experimental data (ablation thresholds, ablation rates) are discussed with respect to the ablation mechanism(s). Adequate tissue removal was observed and the ablation behavior was, in the greates part of the available fluences, almost linear. From the microscopic examination of teh samples, in a scanning electron microscope (SEM), the irradiated surfaces displayed oval craters (reflecting the laser beam shape) with absence of any melting or carbonization zone. It is suggested that the specific laser removes hard tissue by a combined photothermal and plasma mediated ablation mechanism, leaving a surface free from thermal damage and with a well-shaped crater.

  4. Proanthocyanidins Rapidly Stabilize the Demineralized Dentin Layer

    PubMed Central

    Liu, Y.; Dusevich, V.; Wang, Y.

    2013-01-01

    While proanthocyanidins (PA) are effective in improving collagen’s resistance to collagenolytic degradation, the direct incorporation of PA into an adhesive system is detrimental to the light-curing thereof. Conversely, the use of PA as a primer could circumvent this issue, but little is known about the efficacy of PA in stabilizing collagen when applied in a clinically relevant manner. This study investigated the pre- and post-digestion morphology of an acid-etched dentin collagen layer that underwent PA treatment for time periods on a scale of seconds. The null hypothesis, that there is no difference between the PA-treated and untreated control group, had to be rejected, since it was revealed that the untreated control could not survive 1 hr of exogenous collagenase digestion, while the PA-treated collagen could sustain at least 16 hrs of digestion with no perceptible changes in collagen structure. In addition, the stabilizing effect of the gold-standard cross-linker glutaraldehyde at comparable experimental conditions was found to be almost non-existent within the 5, 15, or 30 sec of cross-linking permitted. Therefore, PA have been proven to be extraordinarily efficient in stabilizing demineralized dentin collagen against enzymatic challenges in a clinically relevant setting, likely due to the non-covalent nature of their interaction with collagen molecules. PMID:23723381

  5. Norepinephrines effect on adenosine transport in the proximal straight tubule

    SciTech Connect

    Barfuss, D.W.; McCann, W.P.; Katholi, R.E.

    1986-03-01

    The effect of norepinephrine on C/sup 14/-adenosine transport in the rabbit proximal tubule (S/sub 2/) was studied. The transepithelial transport of adenosine (0.02 mM0 from lumin to bathing solution was measured by its rate of appearance (J/sub A/) in the bathing solution and by its disappearances (J/sub D/) from the luminal fluid. Norepinephrine (0.24 ..mu..M) was added to the bathing solution after a control flux period. After three samples from the experiment period the tubules were quickly harvested and the cellular concentration of C/sup 14/-adenosine was determined. The high cellular adenosine concentration and th marked difference in adenosine appearance rate in the bathing solution compared to the luminal disappearance rate indicates the absorbed adenosine is trapped in the cells. This trapping may be due to adenosine metabolism or difficulty of crossing the basolateral membrane. Whichever is the case, norepinephrine appears to stimulate movement of adenosine or its metabolites into the bathing solution across the basolateral membrane.

  6. Cell volume regulation in the proximal convoluted tubule.

    PubMed

    Gagnon, J; Ouimet, D; Nguyen, H; Laprade, R; Le Grimellec, C; Carrière, S; Cardinal, J

    1982-10-01

    To evaluate the effect of hyper- and hypotonicity on proximal convoluted tubule (PCT) cell volume, nonperfused PCT were studied in vitro with hypertonic solutions containing sodium chloride, urea, or mannitol (450 mosmol/kg H2O) and with hypotonic low sodium chloride solutions (160 mosmol/kg H2O). When the tubules were subjected to hypertonic peritubular solutions containing NaCl, cell volume immediately decreased by 15.5% and remained constant throughout the experimental period (60 min). With mannitol, the initial decrease was identical to that with NaCl (17.7%), but the PCT volume increased slightly during the experimental period. With urea, the decrease in cell volume was smaller (7%) and transient. In hypotonicity, the PCT swelled rapidly, but this swelling was followed by a rapid regulatory phase in which PCT volume nearly returned to control values after less than 10 min. With a potassium-free peritubular medium or 10(-3) M ouabain, the regulatory phase of hypotonicity completely disappeared, whereas the cells did not maintain their reduced volume in NaCl-induced hypertonicity. These results suggest that Na-K-ATPase plays an important role in the maintenance of a reduced cellular volume in hypertonicity and in the regulatory phase of hypotonicity, probably by an active extrusion of sodium and water from the cell.

  7. Acid-base transport by the renal proximal tubule

    PubMed Central

    Skelton, Lara A.; Boron, Walter F.; Zhou, Yuehan

    2015-01-01

    Each day, the kidneys filter 180 L of blood plasma, equating to some 4,300 mmol of the major blood buffer, bicarbonate (HCO3−). The glomerular filtrate enters the lumen of the proximal tubule (PT), and the majority of filtered HCO3− is reclaimed along the early (S1) and convoluted (S2) portions of the PT in a manner coupled to the secretion of H+ into the lumen. The PT also uses the secreted H+ to titrate non-HCO3− buffers in the lumen, in the process creating “new HCO3−” for transport into the blood. Thus, the PT – along with more distal renal segments – is largely responsible for regulating plasma [HCO3−]. In this review we first focus on the milestone discoveries over the past 50+ years that define the mechanism and regulation of acid-base transport by the proximal tubule. Further on in the review, we will summarize research still in progress from our laboratory, work that addresses the problem of how the PT is able to finely adapt to acid–base disturbances by rapidly sensing changes in basolateral levels of HCO3− and CO2 (but not pH), and thereby to exert tight control over the acid–base composition of the blood plasma. PMID:21170887

  8. ADAM17 substrate release in proximal tubule drives kidney fibrosis

    PubMed Central

    Kefaloyianni, Eirini; Muthu, Muthu Lakshmi; Kaeppler, Jakob; Sun, Xiaoming; Sabbisetti, Venkata; Chalaris, Athena; Rose-John, Stefan; Wong, Eitan; Sagi, Irit; Waikar, Sushrut S.; Rennke, Helmut; Bonventre, Joseph V.

    2016-01-01

    Kidney fibrosis following kidney injury is an unresolved health problem and causes significant morbidity and mortality worldwide. In a study into its molecular mechanism, we identified essential causative features. Acute or chronic kidney injury causes sustained elevation of a disintegrin and metalloprotease 17 (ADAM17); of its cleavage-activated proligand substrates, in particular of pro-TNFα and the EGFR ligand amphiregulin (pro-AREG); and of the substrates’ receptors. As a consequence, EGFR is persistently activated and triggers the synthesis and release of proinflammatory and profibrotic factors, resulting in macrophage/neutrophil ingress and fibrosis. ADAM17 hypomorphic mice, specific ADAM17 inhibitor–treated WT mice, or mice with inducible KO of ADAM17 in proximal tubule (Slc34a1-Cre) were significantly protected against these effects. In vitro, in proximal tubule cells, we show that AREG has unique profibrotic actions that are potentiated by TNFα-induced AREG cleavage. In vivo, in acute kidney injury (AKI) and chronic kidney disease (CKD, fibrosis) patients, soluble AREG is indeed highly upregulated in human urine, and both ADAM17 and AREG expression show strong positive correlation with fibrosis markers in related kidney biopsies. Our results indicate that targeting of the ADAM17 pathway represents a therapeutic target for human kidney fibrosis. PMID:27642633

  9. Egress of sperm autoantigen from seminiferous tubules maintains systemic tolerance.

    PubMed

    Tung, Kenneth S K; Harakal, Jessica; Qiao, Hui; Rival, Claudia; Li, Jonathan C H; Paul, Alberta G A; Wheeler, Karen; Pramoonjago, Patcharin; Grafer, Constance M; Sun, Wei; Sampson, Robert D; Wong, Elissa W P; Reddi, Prabhakara P; Deshmukh, Umesh S; Hardy, Daniel M; Tang, Huanghui; Cheng, C Yan; Goldberg, Erwin

    2017-02-20

    Autoimmune responses to meiotic germ cell antigens (MGCA) that are expressed on sperm and testis occur in human infertility and after vasectomy. Many MGCA are also expressed as cancer/testis antigens (CTA) in human cancers, but the tolerance status of MGCA has not been investigated. MGCA are considered to be uniformly immunogenic and nontolerogenic, and the prevailing view posits that MGCA are sequestered behind the Sertoli cell barrier in seminiferous tubules. Here, we have shown that only some murine MGCA are sequestered. Nonsequestered MCGA (NS-MGCA) egressed from normal tubules, as evidenced by their ability to interact with systemically injected antibodies and form localized immune complexes outside the Sertoli cell barrier. NS-MGCA derived from cell fragments that were discarded by spermatids during spermiation. They egressed as cargo in residual bodies and maintained Treg-dependent physiological tolerance. In contrast, sequestered MGCA (S-MGCA) were undetectable in residual bodies and were nontolerogenic. Unlike postvasectomy autoantibodies, which have been shown to mainly target S-MGCA, autoantibodies produced by normal mice with transient Treg depletion that developed autoimmune orchitis exclusively targeted NS-MGCA. We conclude that spermiation, a physiological checkpoint in spermatogenesis, determines the egress and tolerogenicity of MGCA. Our findings will affect target antigen selection in testis and sperm autoimmunity and the immune responses to CTA in male cancer patients.

  10. Analysis of standing droplets in rat proximal tubules

    PubMed Central

    1982-01-01

    Volume, osmolality, and concentrations for Na, Cl, and raffinose have been measured as a function of time in standing droplets within rat intermediate and late proximal tubules. Standing droplet reabsorption proceeds without the development of a measurable osmotic difference across the epithelium. After 140 s of tubular exposure, droplet-to- plasma concentration differences are observed for raffinose, Na, and Cl with the observed Na concentration difference, usually referred to as limiting gradient, being approximately 9 mM. It is possible that a smaller or even no limiting difference would be attained with longer exposure times. Previous values measured for the limiting Na concentration in the rat proximal tubule were determined before the attainment of constant concentrations. Assuming that the Na concentration we measured is the limiting value, we estimate that active NaCl transport accounts for a very small fraction, less than 6%, of the volume reabsorption; using an alternative approach of fitting a theoretical model to our experimental data, active NaCl transport is again estimated to account for only 6% of the total reabsorbate. The previous interpretation that a limiting Na concentration gradient constitutes the most direct evidence for active Na transport may be in error; the gradient we measure can be modeled without incorporating active NaCl transport. PMID:7069399

  11. Axial tubule junctions control rapid calcium signaling in atria

    PubMed Central

    Brandenburg, Sören; Kohl, Tobias; Williams, George S.B.; Rog-Zielinska, Eva A.; Hebisch, Elke; Dura, Miroslav; Didié, Michael; Nikolaev, Viacheslav O.; Hasenfuss, Gerd; Kohl, Peter; Ward, Christopher W.; Lehnart, Stephan E.

    2016-01-01

    The canonical atrial myocyte (AM) is characterized by sparse transverse tubule (TT) invaginations and slow intracellular Ca2+ propagation but exhibits rapid contractile activation that is susceptible to loss of function during hypertrophic remodeling. Here, we have identified a membrane structure and Ca2+-signaling complex that may enhance the speed of atrial contraction independently of phospholamban regulation. This axial couplon was observed in human and mouse atria and is composed of voluminous axial tubules (ATs) with extensive junctions to the sarcoplasmic reticulum (SR) that include ryanodine receptor 2 (RyR2) clusters. In mouse AM, AT structures triggered Ca2+ release from the SR approximately 2 times faster at the AM center than at the surface. Rapid Ca2+ release correlated with colocalization of highly phosphorylated RyR2 clusters at AT-SR junctions and earlier, more rapid shortening of central sarcomeres. In contrast, mice expressing phosphorylation-incompetent RyR2 displayed depressed AM sarcomere shortening and reduced in vivo atrial contractile function. Moreover, left atrial hypertrophy led to AT proliferation, with a marked increase in the highly phosphorylated RyR2-pS2808 cluster fraction, thereby maintaining cytosolic Ca2+ signaling despite decreases in RyR2 cluster density and RyR2 protein expression. AT couplon “super-hubs” thus underlie faster excitation-contraction coupling in health as well as hypertrophic compensatory adaptation and represent a structural and metabolic mechanism that may contribute to contractile dysfunction and arrhythmias. PMID:27643434

  12. A dynamic paracellular pathway serves diuresis in mosquito Malpighian tubules.

    PubMed

    Beyenbach, Klaus W

    2012-07-01

    Female mosquitoes gorge on vertebrate blood, a rich nutrient source for developing eggs, but gorging meals increase the risk of predation. Mosquitoes are quick to reduce the flight payload with a potent diuresis. Diuretic peptides of the insect kinin family induce a tenfold reduction in the paracellular resistance of Malpighian tubules and increase the paracellular permeation of Cl(-), the counterion of the transepithelial secretion of Na(+) and K(+). As a result, the transepithelial secretion of NaCl and KCl and water increases. Insect kinins signal the opening of the paracellular pathway via G protein-coupled receptors and the elevation of intracellular [Ca(2+)], which leads to the reorganization of the cytoskeleton associated with the septate junction (SJ). The reorganization may affect the septate junctional proteins that control the barrier and permselectivity properties of the paracellular pathway. The proteins involved in the embryonic formation of the SJ and in epithelial polarization are largely known for ectodermal epithelia, but the proteins that form and mediate the dynamic functions of the SJ in Malpighian tubules remain to be determined.

  13. In vitro analysis of bond strength of self-etching adhesives applied on superficial and deep dentin.

    PubMed

    Garcia, Eugenio J; Gomes, Osnara M M; Gomes, João C

    2009-01-01

    The purpose of this study was to evaluate the bond strength of three adhesive systems to superficial and deep dentine using the microtensile bond strength test (microTBS). The occlusal enamel of thirty human third molars was removed to expose a flat surface of superficial or deep dentin. For each type of surface, the test specimens were randomly divided into three groups which underwent the application of a conventional two-step adhesive system [Single Bond (SB)] as the control group (n=10), a two-bottle self-etching system [One Coat SE Bond (OCSE)] (n=10) and a one bottle one-step system [Clearfil S3 Bond (CFS3)] (n=10). Adhesives were applied, a 5-mm high "crown" as built-up with resin composite Z250 (3M) and the specimens with a cross-sectional area of 0.7 +/- 0.1 mm2 were tested in tension (0.5 mm/min). Four fractured sticks from each tooth were randomly selected and the dentin side was gently abraded with a 1200-grit SiC paper etched with 35% phosphoric acid for 15 s and air dried. SEM micrographs at 70X and 2400X magnification were taken using scanning electron microscopy (SEM) to calculate the area of tubular dentin (ATD) and tubular density (TD) with Image Pro Plus 5. Two-way ANOVA (dentin depth-adhesive) showed higher bond strength values for SB. However the values did not depend on dentin depth. Linear regression showed a significant relationship between bond strength and area of intertubular dentin for SB (p = 0.004), and a significant inverse relationship between tubular density and bond strength for CFS3 (p = 0.009). OCSE exhibited a tendency that was similar to SB and opposite to CFS3, but was not statistically significant. The conventional two-step adhesive had higher bond strength values. The use of digital image analysis facilitates the manipulation of data and contributes to the interpretation of the behavior of new adhesive systems.

  14. A conserved domain of alkaline phosphatase expression in the Malpighian tubules of dipteran insects.

    PubMed

    Cabrero, Pablo; Pollock, Valerie P; Davies, Shireen A; Dow, Julian A T

    2004-09-01

    Malpighian (renal) tubules are key components of the insect osmoregulatory system and show correspondingly great diversity in both number and length. Recently, the organisation of the Drosophila melanogaster tubule has been elucidated by enhancer trapping, and an array for functional properties has been shown to align with the functional domains. In Drosophila, there is a lower tubule domain, which coincides with expression of alkaline phosphatase and delineates the absorptive region of the tubule. Here, these observations are extended to three dipteran vectors of disease (Aedes aegypti, Anopheles stephensii and Glossina morsitans) and a non-dipteran out-group, Schistocerca gregaria (Orthoptera). Despite a huge range in cell number and size, alkaline phosphatase was found on the apical surface of the lower 10% of each of the dipteran tubules but nowhere within the orthopteran tubule. An alkaline phosphatase lower tubule domain is thus conserved among Diptera. Cell counts are also provided for each species. As in Drosophila, stellate cells are not found in the lower tubule domain of Anopheles or Aedes tubules, confirming the unique genetic identity of this domain. As previously reported, we failed to find stellate cells in Schistocerca but, remarkably, also failed to find them in Glossina, the dipteran most closely related to Drosophila. The orthodoxy that stellate cells are unique to, and general among, Diptera may thus require revision.

  15. Is bovine dentine an appropriate substitute in abrasion studies?

    PubMed

    Wegehaupt, Florian J; Widmer, Raffaella; Attin, Thomas

    2010-04-01

    The study aimed to compare the wear behaviour of human and bovine dentine due to toothbrushing with different relative dentin abrasivity (RDA) toothpastes. Forty human and 40 bovine dentine samples were prepared from bovine lower incisors or human premolars roots, and baseline surface profiles were recorded. The samples were distributed to four groups (each group n = 10 human and 10 bovine samples) and brushed with fluoridated experimental toothpastes with different RDAs (group A: RDA 10, B: RDA 20, C: RDA 50, and D: RDA 100). Toothbrushing was performed in an automatic brushing machine with a brushing frequency of 60 strokes per minute and a brushing force of 2.5 N. After 2, 5, 10, and 25 min of toothbrushing, new surface profiles were recorded, and the dentine wear was calculated with a customized computer programme. The dentine wear of human and bovine dentine within the four groups was compared with unpaired t tests. No statistically significant difference was recorded for the dentine wear of human and bovine samples within the different groups.

  16. Effect of endodontic procedures on root dentin permeability.

    PubMed

    Tao, L; Anderson, R W; Pashley, D H

    1991-12-01

    The purpose of this study was to quantitate the sequential effects of endodontic procedures on the permeability of human root dentin in vitro. Forty single-rooted teeth were used. Both the crown and the apical 2 mm of the root were removed. The hydraulic conductance of the root before and after various endodontic procedures was measured using a fluid filtration method. Measurements were also made of dentin thickness, intracanal diameter changes, and changes in intracanal surface area. The results showed that instrumentation by K files alone or in combination with Gates Glidden drills did not alter radicular dentin permeability when the cementum remained intact. After removing the cementum, the creation of a smear layer and smear plugs on the canal surface tended to offset the expected increase in dentin permeability created by increasing the intracanal surface area and decreasing root dentin thickness. EDTA treatment inside the instrumented canal to remove the smear layer did not increase permeability significantly. The use of K files followed by Gates Glidden drills tended to remove more cervical dentin, increased the intracanal surface area, and increased the hydraulic conductance of root dentin more than the use of K files alone.

  17. Carbodiimide inactivation of MMPs and effect on dentin bonding.

    PubMed

    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

    2014-03-01

    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.

  18. 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

  19. 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

  20. In vitro biofilm formation on the surface of resin-based dentine adhesives.

    PubMed

    Rolland, Sarah L; McCabe, John F; Robinson, Colin; Walls, Angus W G

    2006-06-01

    Prevention of root caries on exposed root surfaces in the aging population is a significant challenge. Bonding resins can be applied to exposed root surfaces as sealants; however, minimal data exists regarding biofilm formation on the surface of these resins. We hypothesized that an antibacterial dentine-bonding resin containing methacryloxydodecyl-pyridiniumbromide (MDPB) may reduce biofilm formation. Biofilms were produced in pooled stimulated natural whole saliva, supplemented with 1% sucrose, on the surface of 5 dentine-bonding resins (Clearfil SE, OptiBond Solo, Protect Bond, Protect Bond Primer, and Xeno III) using untreated root surfaces as controls. Biofilms were stained using the Live:Dead Baclight bacterial viability stain, viewed with confocal microscopy, and analyzed using ImageJ image-analysis software. Resin surfaces encouraged attachment of live bacteria compared with root surfaces. All resins showed similar bacterial colonization in sections adjacent to the resin surface, but in the central and outer portions of biofilms, Xeno III and Protect Bond Primer showed a viable bacterial load similar to that of the root surface. Fluoride-releasing resins (OptiBond Solo/Protect Bond) did not show reduced biofilm formation. Thus, antibacterial agents within the resins have a minimal effect on biofilm formation, particularly when directly adjacent to the root surface.

  1. Nanolayering of phosphoric acid ester monomer on enamel and dentin.

    PubMed

    Yoshihara, Kumiko; Yoshida, Yasuhiro; Hayakawa, Satoshi; Nagaoka, Noriyuki; Irie, Masao; Ogawa, Tatsuyuki; Van Landuyt, Kirsten L; Osaka, Akiyoshi; Suzuki, Kazuomi; Minagi, Shogo; Van Meerbeek, Bart

    2011-08-01

    Following the "adhesion-decalcification" concept, specific functional monomers possess the capacity to primary chemically interact with hydroxyapatite (HAp). Such ionic bonding with synthetic HAp has been demonstrated for 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP), manifest as self-assembled "nanolayering". In continuation of that basic research this study aimed to explore whether nanolayering also occurs on enamel and dentin when a 10-MDP primer is applied following a common clinical application protocol. Therefore, the interaction of an experimental 10-MDP primer and a control, commercially available, 10-MDP-based primer (Clearfil SE Bond primer (C-SE), Kuraray) with enamel and dentin was characterized by X-ray diffraction (XRD), complemented with transmission electron microscopy interfacial ultrastructural data upon their reaction with enamel and dentin. In addition, XRD was used to study the effect of the concentration of 10-MDP on nanolayering on dentin. Finally, the stability of the nanolayers was determined by measuring the bond strength to enamel and dentin when a photoinitiator was added to the experimental primer or when interfacial polymerization depended solely on the photoinitiator supplied with the subsequently applied adhesive resin. XRD confirmed nanolayering on enamel and dentin, which was significantly greater on dentin than on enamel, and also when the surface was actively rubbed with the primer. Nanolayering was also proportional to the concentration of 10-MDP in the primer. Finally, the experimental primer needed the photoinitiator to obtain a tensile bond strength to dentin comparable with that of the control C-SE primer (which also contains a photoinitiator), but not when bonded to enamel. It is concluded that self-assembled nanolayering occurs on enamel and dentin, even when following a clinically used application protocol. The lower bonding effectiveness of mild self-etch adhesives to enamel should be ascribed in part to a lower

  2. Self-etching adhesives increase collagenolytic activity in radicular dentin.

    PubMed

    Tay, Franklin R; Pashley, David H; Loushine, Robert J; Weller, R Norman; Monticelli, Francesca; Osorio, Raquel

    2006-09-01

    Endogenous matrix metalloproteinases (MMPs) release from crown dentin and their activation results in degradation of hybrid layers created by dentin adhesives. This study tested the hypothesis that instrumented intraradicular dentin possesses latent collagenolytic activity that is activated by mild self-etching adhesives. Root dentin shavings were produced from 50 cleaned and shaped, saline-irrigated root canals using Gates Glidden drills and rinsed with sodium azide to prevent bacterial growth. Dried dentin powder aliquots were treated with two clinically-relevant MMP inhibitors, 2% chlorhexidine for 10 minutes and 17% EDTA for 1 minute. Additional dentin powder was mixed with Clearfil Liner Bond 2V or Clearfil Tri-S Bond for 1 minute followed by extracting the adhesives with acetone. Dentin powder was also treated with 2% chlorhexidine for 10 minutes before or after adhesive application. Collagenolytic activities of the nine groups were assayed with a fluorometer in 96-well plates, by recording the changes in fluorescence before and after addition of fluorescein-labeled type I collagen. Epoxy resin-embedded powders were examined with TEM for the extent of demineralization. Instrumented, mineralized intraradicular dentin possessed low but detectable collagenolytic activity that was inhibited by chlorhexidine (p < 0.001) and EDTA (p < 0.001). Both adhesives partially demineralized the dentin powder and activated latent MMPs, with 14- to 15-fold increases in collagenolytic activities (p < 0.001) that were significantly (p < 0.001) but incompletely inactivated after 10 min application of chlorhexidine. Mild self-etching adhesives activate latent MMPs without denaturing these enzymes, and may adversely affect the longevity of bonded root canal fillings and posts.

  3. Role of dentin MMPs in caries progression and bond stability.

    PubMed

    Mazzoni, A; Tjäderhane, L; Checchi, V; Di Lenarda, R; Salo, T; Tay, F R; Pashley, D H; Breschi, L

    2015-02-01

    Dentin can be described as a biological composite with collagen matrix embedded with nanosized hydroxyapatite mineral crystallites. Matrix metalloproteinases (MMPs) and cysteine cathepsins are families of endopeptidases. Enzymes of both families are present in dentin and collectively capable of degrading virtually all extracellular matrix components. This review describes these enzymes and their presence in dentin, mainly focusing on their role in dentin caries pathogenesis and loss of collagen in the adhesive hybrid layer under composite restorations. MMPs and cysteine cathepsins present in saliva, mineralized dentin, and/or dentinal fluid may affect the dentin caries process at the early phases of demineralization. Changes in collagen and noncollagenous protein structure may participate in observed decreases in mechanical properties of caries-affected dentin and reduce the ability of caries-affected dentin to remineralize. These endogenous enzymes also remain entrapped within the hybrid layer during the resin infiltration process, and the acidic bonding agents themselves (irrespective of whether they are etch-and-rinse or self-etch) can activate these endogenous protease proforms. Since resin impregnation is frequently incomplete, denuded collagen matrices associated with free water (which serves as a collagen cleavage reagent for these endogenous hydrolase enzymes) can be enzymatically disrupted, finally contributing to the degradation of the hybrid layer. There are multiple in vitro and in vivo reports showing that the longevity of the adhesive interface is increased when nonspecific enzyme-inhibiting strategies are used. Different chemicals (i.e., chlorhexidine, galardin, and benzalkonium chloride) or collagen cross-linker agents have been successfully employed as therapeutic primers in the bonding procedure. In addition, the incorporation of enzyme inhibitors (i.e., quaternary ammonium methacrylates) into the resin blends has been recently promoted. This

  4. Role of Dentin MMPs in Caries Progression and Bond Stability

    PubMed Central

    Mazzoni, A.; Tjäderhane, L.; Checchi, V.; Di Lenarda, R.; Salo, T.; Tay, F.R.; Pashley, D.H.

    2015-01-01

    Dentin can be described as a biological composite with collagen matrix embedded with nanosized hydroxyapatite mineral crystallites. Matrix metalloproteinases (MMPs) and cysteine cathepsins are families of endopeptidases. Enzymes of both families are present in dentin and collectively capable of degrading virtually all extracellular matrix components. This review describes these enzymes and their presence in dentin, mainly focusing on their role in dentin caries pathogenesis and loss of collagen in the adhesive hybrid layer under composite restorations. MMPs and cysteine cathepsins present in saliva, mineralized dentin, and/or dentinal fluid may affect the dentin caries process at the early phases of demineralization. Changes in collagen and noncollagenous protein structure may participate in observed decreases in mechanical properties of caries-affected dentin and reduce the ability of caries-affected dentin to remineralize. These endogenous enzymes also remain entrapped within the hybrid layer during the resin infiltration process, and the acidic bonding agents themselves (irrespective of whether they are etch-and-rinse or self-etch) can activate these endogenous protease proforms. Since resin impregnation is frequently incomplete, denuded collagen matrices associated with free water (which serves as a collagen cleavage reagent for these endogenous hydrolase enzymes) can be enzymatically disrupted, finally contributing to the degradation of the hybrid layer. There are multiple in vitro and in vivo reports showing that the longevity of the adhesive interface is increased when nonspecific enzyme-inhibiting strategies are used. Different chemicals (i.e., chlorhexidine, galardin, and benzalkonium chloride) or collagen cross-linker agents have been successfully employed as therapeutic primers in the bonding procedure. In addition, the incorporation of enzyme inhibitors (i.e., quaternary ammonium methacrylates) into the resin blends has been recently promoted. This

  5. Effect of Er,Cr:YSGG Laser at Different Output Powers on the Micromorphology and the Bond Property of Non-Carious Sclerotic Dentin to Resin Composites

    PubMed Central

    Wang, Weiguo; Jiao, Yang; Wang, Wanshan; Yang, Yanwei; Wei, Jingjing; Shen, Lijuan; Chen, Jihua

    2015-01-01

    Background The objective of this study was to investigate the influence of Er,Cr:YSGG laser irradiated at different powers on the micromorphology and the bonding property of non-carious sclerotic dentin to resin composites. Methods Two hundred bovine incisors characterized by non-carious sclerotic dentin were selected, and the seventy-two teeth of which for surface morphological analysis were divided into nine groups according to various treatments (A: the control group, B: only treated with the adhesive Adper Easy One, C: diamond bur polishing followed by Adper Easy One, D-I: Er,Cr:YSGG laser irradiating at 1W, 2W, 3W, 4W, 5W, 6W output power, respectively, followed by Adper Easy One). The surface roughness values were measured by the non-contact three-dimensional morphology scanner, then the surface micromorphologies of surfaces in all groups were assessed by scanning electron microscopy (SEM); meanwhile, Image Pro-Plus 6.0 software was used to measure the relative percentage of open tubules on SEM images. The rest, one hundred twenty-eight teeth for bond strength test, were divided into eight groups according to the different treatments (A: only treated with the adhesive Adper Easy One, B: diamond bur polishing followed by the above adhesive, C-H: Er,Cr:YSGG laser irradiating at 1 W, 2 W, 3 W, 4 W, 5 W, 6 W output power, respectively, followed by the above adhesive), and each group was subsequently divided into two subgroups according to whether aging is performed (immediately tested and after thermocycling). Micro-shear bond strength test was used to evaluate the bond strength. Results The 4W laser group showed the highest roughness value (30.84±1.93μm), which was statistically higher than the control group and the diamond bur groups (p<0.05). The mean percentages ((27.8±1.8)%, (28.0±2.2)%, (30.0±1.9)%) of open tubules area in the 4W, 5W, 6W group were higher than other groups (p<0.05). The 4W laser group showed the highest micro-shear bond strength not

  6. Fatigue of the Resin-Dentin Interface: A New Approach for Evaluating the Durability of Dentin Bonds

    PubMed Central

    Mutluay, Mustafa Murat; Yahyazadefar, Mobin; Ryou, Heonjune; Majd, Hessam; Do, Dominic; Arola, Dwayne

    2013-01-01

    There are concerns regarding the longevity of resin composite restorations and the clinical relevance of in vitro bond strength testing to the durability of dentin bonds in vivo. Objective The objectives of this investigation were to: 1) develop a new method of experimental evaluation for quantifying the durability of dentin bonds, 2) apply this method to characterize the interfacial strength of a selected commercial system under both monotonic and cyclic loading, and 3) distinguish mechanisms contributing to the interface degradation and failure. Methods A new method for fatigue testing the resin-dentin interface was developed based on a four-point flexure arrangement that includes two identical bonded interfaces. Cyclic loading of specimens comprised of coronal dentin bonded to a commercial resin composite and controls of resin composite was performed to failure within a hydrated environment. Scanning electron microscopy and nanoscopic dynamic mechanical analysis were used to evaluate failure mechanisms. Results The fatigue strength of the resin-dentin interface was significantly lower (p≤0.0001) than that of the resin composite and reported for dentin over the entire finite life regime. Defined at 1×107 cycles, the apparent endurance limit of the resin-dentin interface was 13 MPa, in comparison to 48 MPa and 44 MPa for the resin composite and dentin, respectively. The ratio of fully reversed endurance limit to ultimate strength of the interface (0.26) was the lowest of the three materials. Significance The proposed approach for characterizing the fatigue strength of resin-dentin bonds may offer new insights concerning durability of the bonded interface. PMID:23434232

  7. Resin bond strength to water versus ethanol-saturated human dentin pretreated with three different cross-linking agents

    PubMed Central

    Venigalla, Bhuvan Shome; Jyothi, Pinnamreddy; Kamishetty, Shekhar; Reddy, Smitha; Cherukupalli, Ravi Chandra; Reddy, Depa Arun

    2016-01-01

    Context: Resin-dentin bonds are unstable owing to hydrolytic and enzymatic degradation. Several approaches such as collagen cross-linking and ethanol-wet bonding (EWB) have been developed to overcome this problem. Collagen cross-linking improves the intrinsic properties of the collagen matrix. However, it leaves a water-rich collagen matrix with incomplete resin infiltration making it susceptible to fatigue degradation. Since EWB is expected to overcome the drawbacks of water-wet bonding (WWB), a combination of collagen cross-linking with EWB was tested. Aim: The aim of this study was to compare the effect of pretreatment with different cross-linking agents such as ultraviolet A (UVA)-activated 0.1% riboflavin, 1 M carbodiimide, and 6.5 wt% proanthocyanidin on the immediate and long-term bond strengths of an etch and rinse adhesive system to water- versus ethanol-saturated dentin within clinically relevant application time periods. Settings and Design: Long-term in vitro study evaluating the microtensile bond strength of adhesive-dentin interface after different surface pretreatments. Subjects and Methods: Eighty freshly extracted human molars were prepared to expose dentin, etched with 37% phosphoric acid for 15 s rinsed, and grouped randomly. They were blot-dried and pretreated with different cross-linkers: 0.1% riboflavin for 2 min followed by UVA activation for 2 min; 1 M carbodiimide for 2 min; 6.5 wt% proanthocyanidin for 2 min and rinsed. They were then bonded with Adper Single Bond Adhesive (3M ESPE), by either WWB or EWB, followed by resin composite build-ups (Filtek Z350, 3M ESPE). Bonded specimens in each group were then sectioned and divided into two halves. Microtensile bond strength was tested in one half after 24 h and the other after 6 months storage in artificial saliva. Statistical Analysis Used: Analysis was done using SPSS version 18 software (SPSS Inc., Chicago, IL, USA). Intergroup comparison of bond strength was done using ANOVA with post hoc

  8. Dentinal fluid dynamics in human teeth, in vivo.

    PubMed

    Ciucchi, B; Bouillaguet, S; Holz, J; Pashley, D

    1995-04-01

    Cavities were prepared in human premolars scheduled for extraction for orthodontic reasons. The smear layer was removed from the dentin surface by acid etching, and the cavity was sealed using a hollow chamber. The chamber was filled with sterile saline solution and connected via tubing to a hydraulic circuit featuring an adjustable pressure reservoir and a device that measures fluid movement across dentin. In the absence of any exogenous pressure, all cavities exhibited an outward fluid flow rate of 0.36 microliters min-1 cm-2. As exogenous pressure was applied to the cavity, the outward flow slowed. The exogenous pressure that stopped outward fluid flow was taken to be equal to normal pulpal tissue pressure. The mean value was 14.1 cm H2O in five teeth. This simple method permits measurement of dentinal fluid flux, the hydraulic conductance of dentin, and estimates pulpal tissue pressure.

  9. Dentin permeability: effects of temperature on hydraulic conductance.

    PubMed

    Pashley, D H; Thompson, S M; Stewart, F P

    1983-09-01

    The rates of fluid movement across dentin discs, in vitro, were measured at 10, 20, 30, 40, and 50 degrees C in unetched and acid-etched dentin. Increasing the temperature 40 degrees (i.e., from 10 to 50 degrees C) resulted in a 1.8-fold increase in fluid flow in unetched dentin, which was of a magnitude similar to the decrease in viscosity that occurred over the same temperature range. In acid-etched dentin, the 40 degrees C temperature change produced more than a four-fold increase in fluid conductance, more than double that which could be accounted for by changes in viscosity. Analysis of the data suggests that this additional increment in hydraulic conductance is due to thermal expansion-induced increases in tubular diameter.

  10. Role of Alcohol on the Fracture Resistance of Dentin

    SciTech Connect

    Nalla, Ravi K.; Kinney, John H.; Tomsia, Antoni P.; Ritchie,Robert O.

    2006-05-01

    Healthy dentin, the mineralized tissue that makes up the bulk of the tooth, is naturally hydrated in vivo; however, it is known that various chemical reagents including acetone and ethanol can induce dehydration and thereby affect its properties. Here, we seek to investigate this in light of the effect alcohol can have on the mechanical properties of dentin, specifically by measuring the stiffness, strength and toughness of dentin in simulated body fluid and scotch whisky. Results indicate that chemical dehydration induced by the whisky has a significant beneficial effect on the elastic modulus, strength and fracture toughness of dentin. Although this makes teeth more resistant to fracture, the change in properties is fully reversible upon rehydration. This effect is considered to be associated with increased cross-linking of the collagen molecules from intermolecular hydrogen-bonding where water is replaced with weaker hydrogen-bond forming solvents such as alcohol.

  11. Effectiveness of Lasers in the Treatment of Dentin Hypersensitivity

    PubMed Central

    Asnaashari, Mohammad; Moeini, Masoumeh

    2013-01-01

    Dentin hypersensitivity (DH) is a relatively common painful condition among dental problems. Although many studies have been performed regarding the diagnosis and treatment of DH, dental practitioners are still confused about the definite diagnosis and treatment.The use of lasers as a treatment for dentin hypersensitivity was first introduced in 1985.Laser treatment in dentin hypersensitivity is an interesting and controversial issue and many investigations have been done on its mechanism of action, advantages, and unclear points.The present literature review tries to go over the definition, diagnosis, etiology , predisposing factors, various laser types in the treatment of DH alone or in combination with topical desensitizing agents. Since a certain treatment has not yet introduced for dentin hypersensitivity, a combination of laser therapy and topical desensitizing factors ,can increase the success of the treatment compared with either treatments alone. PMID:25606300

  12. Kidney tubules: intertubular, vascular, and glomerular cross-talk

    PubMed Central

    Ferenbach, David A.; Bonventre, Joseph V.

    2016-01-01

    Purpose of review The kidney mediates the excretion or conservation of water and electrolytes in the face of changing fluid and salt intake and losses. To ultrafilter and reabsorb the exact quantities of free water and salts to maintain euvolemia a range of endocrine, paracrine, and hormonal signaling systems have evolved linking the tubules, capillaries, glomeruli, arterioles, and other intrinsic cells of the kidney. Our understanding of these systems remains incomplete. Recent findings Recent work has provided new insights into the workings of the communication pathways between tubular segments and the glomeruli and vasculature, with novel therapeutic agents in development. Particular progress has also been made in the visualization of tubuloglomerular feedback. Summary The review summarizes our current understanding of pathway functions in health and disease, as well as future therapeutic options to protect the healthy and injured kidney. PMID:27023838

  13. LIPOPROTEIN GRANULES IN THE CORTICAL COLLECTING TUBULES OF MOUSE KIDNEY

    PubMed Central

    Miller, Fritz

    1961-01-01

    The light and, to a lesser extent, the dark cells of the cortical collecting tubules in mouse kidney contain a great number of granules which according to histochemical tests are composed of phospholipids and proteins. These granules are bounded by a triple-layered membrane measuring approximately 75 A across, and contain one or several crystals with a hexagonal or square lattice. These crystals are built up of rod-shaped units, which appear dense after osmium fixation, measure about 48 A in diameter, and are separated by a light interspace of similar dimensions. The mean center-to-center distance of the rods is about 96 A. The structure is explained as a lipoprotein crystallized within a membrane-bounded vacuole. No relationship between these granules and mitochondria was found. The physiological significance of the granules remains unknown. PMID:13770761

  14. Static analysis of masonry kilns built with fictile tubules bricks

    NASA Astrophysics Data System (ADS)

    Olivito, Renato S.; Scuro, Carmelo; Codispoti, Rosamaria

    2016-12-01

    Industrial archeology is a branch that studies all the testimony (tangible and intangible, direct and indirect) related to the process of industrialization since its origins. This technical field is based on an interdisciplinary approach, it has the task of deepening the story, understanding the technological development made by man over the centuries. The present work focused attention on the study and analysis of a masonry kiln, built with the technique of hollow clay fictile tubules. The study, in particular, has been carried out analyzing the stress state caused by the wind on the structure. The kiln is constituted by a particular geometric configuration that develops in height due to the presence of chimney over the dome.

  15. A New Look at Electrolyte Transport in the Distal Tubule

    PubMed Central

    Eladari, Dominique; Chambrey, Régine; Peti-Peterdi, Janos

    2015-01-01

    The distal nephron plays a critical role in the renal control of homeostasis. Until very recently most studies focused on the control of Na+, K+, and water balance by principal cells of the collecting duct and the regulation of solute and water by hormones from the renin-angiotensin-aldosterone system and by antidiuretic hormone. However, recent studies have revealed the unexpected importance of renal intercalated cells, a subtype of cells present in the connecting tubule and collecting ducts. Such cells were thought initially to be involved exclusively in acid-base regulation. However, it is clear now that intercalated cells absorb NaCl and K+ and hence may participate in the regulation of blood pressure and potassium balance. The second paradigm-challenging concept we highlight is the emerging importance of local paracrine factors that play a critical role in the renal control of water and electrolyte balance. PMID:21888509

  16. A new look at electrolyte transport in the distal tubule.

    PubMed

    Eladari, Dominique; Chambrey, Régine; Peti-Peterdi, Janos

    2012-01-01

    The distal nephron plays a critical role in the renal control of homeostasis. Until very recently most studies focused on the control of Na(+), K(+), and water balance by principal cells of the collecting duct and the regulation of solute and water by hormones from the renin-angiotensin-aldosterone system and by antidiuretic hormone. However, recent studies have revealed the unexpected importance of renal intercalated cells, a subtype of cells present in the connecting tubule and collecting ducts. Such cells were thought initially to be involved exclusively in acid-base regulation. However, it is clear now that intercalated cells absorb NaCl and K(+) and hence may participate in the regulation of blood pressure and potassium balance. The second paradigm-challenging concept we highlight is the emerging importance of local paracrine factors that play a critical role in the renal control of water and electrolyte balance.

  17. Isovolumetric regulation of renal proximal tubules in hypotonic medium.

    PubMed

    Lohr, J W

    1990-01-01

    Isolated nonperfused proximal tubules maintained their cell volume at a constant level (isovolumetric regulation, IVR), when osmolality of the bathing medium was gradually decreased from 290 to 190 mosm at 1.5 and 5.0 mosm/min. Hypotonic IVR was blocked by inhibiting the Na(+)-K+ pump with ouabain (10(-4) M) when osmolality was decreased at 1.5 or 5 mosm/min. Concentration-dependent inhibition of cell volume maintenance was observed in the presence of the K+ channel blocker barium (10(-3)-10(-2) M) when osmolality decreased at 5 mosm/min. Quinine (10(-3) M), another K+ channel blocker, also inhibited IVR at osmolality decreases of 1.5 and 5 mosm/min. These results suggest that the maintenance of constant cell volume during gradual hypoosmotic exposure involves mechanisms that depend on intact Na-K-ATPase and the controlled loss of intracellular K+.

  18. Proximal Tubule Cell Hypothesis for Cardiorenal Syndrome in Diabetes

    PubMed Central

    Saito, Akihiko; Kaseda, Ryohei; Hosojima, Michihiro; Sato, Hiroyoshi

    2011-01-01

    Incidence of cardiovascular disease (CVD) is remarkably high among patients with chronic kidney disease (CKD), even in the early microalbuminuric stages with normal glomerular filtration rates. Proximal tubule cells (PTCs) mediate metabolism and urinary excretion of vasculotoxic substances via apical and basolateral receptors and transporters. These cells also retrieve vasculoprotective substances from circulation or synthesize them for release into the circulation. PTCs are also involved in the uptake of sodium and phosphate, which are critical for hemodynamic regulation and maintaining the mineral balance, respectively. Dysregulation of PTC functions in CKD is likely to be associated with the development of CVD and is linked to the progression to end-stage renal disease. In particular, PTC dysfunction occurs early in diabetic nephropathy, a leading cause of CKD. It is therefore important to elucidate the mechanisms of PTC dysfunction to develop therapeutic strategies for treating cardiorenal syndrome in diabetes. PMID:21197105

  19. Innovative approaches to regenerate enamel and dentin.

    PubMed

    Chatzistavrou, Xanthippi; Papagerakis, Silvana; Ma, Peter X; Papagerakis, Petros

    2012-01-01

    The process of tooth mineralization and the role of molecular control of cellular behavior during embryonic tooth development have attracted much attention the last few years. The knowledge gained from the research in these fields has improved the general understanding about the formation of dental tissues and the entire tooth and set the basis for teeth regeneration. Tissue engineering using scaffold and cell aggregate methods has been considered to produce bioengineered dental tissues, while dental stem/progenitor cells, which can differentiate into dental cell lineages, have been also introduced into the field of tooth mineralization and regeneration. Some of the main strategies for making enamel, dentin, and complex tooth-like structures are presented in this paper. However, there are still significant barriers that obstruct such strategies to move into the regular clinic practice, and these should be overcome in order to have the regenerative dentistry as the important mean that can treat the consequences of tooth-related diseases.

  20. Cardiac Spliced BIN1 Folds T-tubule Membrane, Controlling Ion Flux and Limiting Arrhythmia

    PubMed Central

    Hong, TingTing; Yang, Huanghe; Zhang, Shan-Shan; Cho, Hee Cheol; Kalashnikova, Mariya; Sun, Baiming; Zhang, Hao; Bhargava, Anamika; Grabe, Michael; Olgin, Jeffrey; Gorelik, Julia; Marbán, Eduardo; Jan, Lily Y.; Shaw, Robin M.

    2014-01-01

    Cardiomyocyte T-tubules are important for regulating ionic flux. Bridging Integrator 1 (BIN1) is a T-tubule protein associated with calcium channel trafficking that is down-regulated in failing hearts. Here we find that cardiac T-tubules normally contain dense protective inner membrane folds that are formed by a cardiac spliced isoform of BIN1. In mice with cardiac Bin1 deletion, T-tubule folding is decreased which does not change overall cardiomyocyte morphology, but frees diffusion of local extracellular calcium and potassium ions, prolonging action potential duration, and increasing susceptibility to ventricular arrhythmias. We also find that T-tubule inner folds are rescued only by the BIN1 isoform BIN1+13+17, which promotes N-WASP dependent actin polymerization to stabilize T-tubule membrane at cardiac Z-discs. In conclusion, BIN1+13+17 recruits actin to fold T-tubule membrane, creating a fuzzy space that protectively restricts ionic flux. When BIN1+13+17 is decreased, as occurs in acquired cardiomyopathy, T-tubule morphology is altered and arrhythmias can result. PMID:24836577

  1. Autoradiographic Localization of [3H]Gentamicin in the Proximal Renal Tubules of Mice

    PubMed Central

    Kuhar, Michael J.; Mak, Linda L.; Lietman, Paul S.

    1979-01-01

    The site of localization of [3H]gentamicin within mouse kidney is shown to be the proximal renal tubule by coincidence of the radioactivity, as visualized by autoradiography, and the mucopolysaccharide-rich microvilli characteristic of proximal convoluted tubules, as visualized by histochemical staining. Images PMID:426500

  2. SGLT2 mediates glucose reabsorption in the early proximal tubule.

    PubMed

    Vallon, Volker; Platt, Kenneth A; Cunard, Robyn; Schroth, Jana; Whaley, Jean; Thomson, Scott C; Koepsell, Hermann; Rieg, Timo

    2011-01-01

    Mutations in the gene encoding for the Na(+)-glucose co-transporter SGLT2 (SLC5A2) associate with familial renal glucosuria, but the role of SGLT2 in the kidney is incompletely understood. Here, we determined the localization of SGLT2 in the mouse kidney and generated and characterized SGLT2-deficient mice. In wild-type (WT) mice, immunohistochemistry localized SGLT2 to the brush border membrane of the early proximal tubule. Sglt2(-/-) mice had glucosuria, polyuria, and increased food and fluid intake without differences in plasma glucose concentrations, GFR, or urinary excretion of other proximal tubular substrates (including amino acids) compared with WT mice. SGLT2 deficiency did not associate with volume depletion, suggested by similar body weight, BP, and hematocrit; however, plasma renin concentrations were modestly higher and plasma aldosterone levels were lower in Sglt2(-/-) mice. Whole-kidney clearance studies showed that fractional glucose reabsorption was significantly lower in Sglt2(-/-) mice compared with WT mice and varied in Sglt2(-/-) mice between 10 and 60%, inversely with the amount of filtered glucose. Free-flow micropuncture revealed that for early proximal collections, 78 ± 6% of the filtered glucose was reabsorbed in WT mice compared with no reabsorption in Sglt2(-/-) mice. For late proximal collections, fractional glucose reabsorption was 93 ± 1% in WT and 21 ± 6% in Sglt2(-/-) mice, respectively. These results demonstrate that SGLT2 mediates glucose reabsorption in the early proximal tubule and most of the glucose reabsorption by the kidney, overall. This mouse model mimics and explains the glucosuric phenotype of individuals carrying SLC5A2 mutations.

  3. Silencing megalin and cubilin genes inhibits myeloma light chain endocytosis and ameliorates toxicity in human renal proximal tubule epithelial cells.

    PubMed

    Li, Min; Balamuthusamy, Saravanan; Simon, Eric E; Batuman, Vecihi

    2008-07-01

    Using target-specific short interfering (si) RNAs, we silenced the tandem endocytic receptors megalin and cubilin genes in cultured human renal proximal tubule epithelial cells. Transfection by siRNA resulted in up to 90% suppression of both megalin and cubilin protein and mRNA expression. In HK-2 cells exposed to kappa-light chain for up to 24 h, light chain endocytosis was reduced in either megalin- or cubilin-silenced cells markedly but incompletely. Simultaneous silencing of both the cubilin and megalin genes, however, resulted in near-complete inhibition of light chain endocytosis, as determined by measuring kappa-light chain protein concentration in cell cytoplasm and by flow cytometry using FITC-labeled kappa-light chain. In these cells, light chain-induced cytokine responses (interleukin-6 and monocyte chemoattractant protein-1) and epithelial-to-mesenchymal transition as well as the associated cellular and morphological alterations were also markedly suppressed. The results demonstrate that light chain endocytosis is predominantly mediated by the megalin-cubilin tandem endocytic receptor and identify endocytosis as a key step in light chain cytotoxicity. Blocking light chain endocytosis prevents its nephrotoxic effects on human kidney proximal tubule cells.

  4. Regional variability in the permeability of human dentine.

    PubMed

    Pashley, D H; Andringa, H J; Derkson, G D; Derkson, M E; Kalathoor, S R

    1987-01-01

    This was measured qualitatively by using dyes and quantitatively by hydraulic conductance in dentine discs and crown segments in vitro. Both types of preparation demonstrated large regional differences in permeability, with the highest values at the periphery and the lowest in the centre of the disc or crown. As dentine permeability may vary 3-10-fold across a few millimetres, investigators should use as large a surface area as possible to compensate for these regional differences.

  5. Mesenchymal Dental Pulp Cells Attenuate Dentin Resorption in Homeostasis

    PubMed Central

    Zheng, Y.; Chen, M.; He, L.; Marão, H.F.; Sun, D.M.; Zhou, J.; Kim, S.G.; Song, S.; Wang, S.L.

    2015-01-01

    Dentin in permanent teeth rarely undergoes resorption in development, homeostasis, or aging, in contrast to bone that undergoes periodic resorption/remodeling. The authors hypothesized that cells in the mesenchymal compartment of dental pulp attenuate osteoclastogenesis. Mononucleated and adherent cells from donor-matched rat dental pulp (dental pulp cells [DPCs]) and alveolar bone (alveolar bone cells [ABCs]) were isolated and separately cocultured with primary rat splenocytes. Primary splenocytes readily aggregated and formed osteoclast-like cells in chemically defined osteoclastogenesis medium with 20 ng/mL of macrophage colony-stimulating factor (M-CSF) and 50 ng/mL of receptor activator of nuclear factor κB ligand (RANKL). Strikingly, DPCs attenuated osteoclastogenesis when cocultured with primary splenocytes, whereas ABCs slightly but significantly promoted osteoclastogenesis. DPCs yielded ~20-fold lower RANKL expression but >2-fold higher osteoprotegerin (OPG) expression than donor-matched ABCs, yielding a RANKL/OPG ratio of 41:1 (ABCs:DPCs). Vitamin D3 significantly promoted RANKL expression in ABCs and OPG in DPCs. In vivo, rat maxillary incisors were atraumatically extracted (without any tooth fractures), followed by retrograde pulpectomy to remove DPCs and immediate replantation into the extraction sockets to allow repopulation of the surgically treated root canal with periodontal and alveolar bone–derived cells. After 8 wk, multiple dentin/root resorption lacunae were present in root dentin with robust RANKL and OPG expression. There were areas of dentin resoprtion alternating with areas of osteodentin formation in root dentin surface in the observed 8 wk. These findings suggest that DPCs of the mesenchymal compartment have an innate ability to attenuate osteoclastogenesis and that this innate ability may be responsible for the absence of dentin resorption in homeostasis. Mesenchymal attenuation of dentin resorption may have implications in internal

  6. Morphological effects of MMPs inhibitors on the dentin bonding.

    PubMed

    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.

  7. Resin–Dentin Bonding Interface After Photochemical Surface Treatment

    PubMed Central

    Sano, Kazunobu; Ichinose, Shizuko; Araki, Kouji

    2015-01-01

    Abstract Objective The aim of this study is to elucidate the structure of the resin–dentin interface formed by photochemical dentin treatment using an argon fluoride (ArF) excimer laser. Background data The ArF excimer laser processes material by photochemical reaction without generating heat, while also providing surface conditioning that enhances material adhesion. In the case of bonding between resin and dentin, we demonstrated in a previous study that laser etching using an ArF excimer laser produced bonding strength comparable to that of the traditional bonding process; however, conditions of the bonding interface have not been fully investigated. Methods A dentin surface was irradiated in air with an ArF excimer laser followed by bonding treatment. Cross sections were observed under light microscope, transmission electron microscope (TEM), and scanning electron microscope, then analyzed using an energy dispersive X-ray spectroscope (EDS): EDS line profiles of the elements C, O, Si, Cl, P, and Ca at the resin–dentin interface were obtained. Results The density of C in resin decreased as it approached the interface, reaching its lowest level within the dentin at a depth of 2 μm from the resin–dentin interface on EDS. There was no hybrid layer observed at the interface on TEM. Therefore, it was suggested that the resin monomer infiltrated into the microspaces produced on the dentin surface by laser abrasion. Conclusions The monomer infiltration without hybrid layer is thought to be the adhesion mechanism after laser etching. Therefore, the photochemical processes at the bonding interface achieved using the ArF excimer laser has great potential to be developed into a new bonding system in dentistry. PMID:25555032

  8. 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

  9. Quantification of peroxide ion passage in dentin, enamel, and cementum after internal bleaching with hydrogen peroxide.

    PubMed

    Palo, R M; Bonetti-Filho, I; Valera, M C; Camargo, C H R; Camargo, Sea; Moura-Netto, C; Pameijer, C

    2012-01-01

    The aim of this study was to evaluate the amount of peroxide passage from the pulp chamber to the external enamel surface during the internal bleaching technique. Fifty bovine teeth were sectioned transversally 5 mm below the cemento-enamel junction (CEJ), and the remaining part of the root was sealed with a 2-mm layer of glass ionomer cement. The external surface of the samples was coated with nail varnish, with the exception of standardized circular areas (6-mm diameter) located on the enamel, exposed dentin, or cementum surface of the tooth. The teeth were divided into three experimental groups according to exposed areas close to the CEJ and into two control groups (n=10/group), as follows: GE, enamel exposure area; GC, cementum exposed area; GD, dentin exposed area; Negative control, no presence of internal bleaching agent and uncoated surface; and Positive control, pulp chamber filled with bleaching agent and external surface totally coated with nail varnish. The pulp chamber was filled with 35% hydrogen peroxide (Opalescence Endo, Ultradent). Each sample was placed inside of individual flasks with 1000 μL of acetate buffer solution, 2 M (pH 4.5). After seven days, the buffer solution was transferred to a glass tube, in which 100 μL of leuco-crystal violet and 50 μL of horseradish peroxidase were added, producing a blue solution. The optical density of the blue solution was determined by spectrophotometer and converted into microgram equivalents of hydrogen peroxide. Data were submitted to Kruskal-Wallis and Dunn-Bonferroni tests (α=0.05). All experimental groups presented passage of peroxide to the external surface that was statistically different from that observed in the control groups. It was verified that the passage of peroxide was higher in GD than in GE (p<0.01). The GC group presented a significantly lower peroxide passage than did GD and GE (p<0.01). It can be concluded that the hydrogen peroxide placed into the pulp chamber passed through the

  10. Characterization of riboflavin-modified dentin collagen matrix.

    PubMed

    Fawzy, A; Nitisusanta, L; Iqbal, K; Daood, U; Beng, L T; Neo, J

    2012-11-01

    Crosslinking is considered a possible approach to increasing the mechanical and structural stability and biodegradation resistance of the dentin collagen matrix. The aim of this study was to investigate the mechanical and chemical variations and collagen degradation resistance associated with crosslinking of the dentin collagen matrix with UVA-activated riboflavin. Dentin collagen matrix specimens were treated with 0.1 and 1% riboflavin for 2 min and photo-activated with 7 mW/cm(2) UVA (368 nm) for 2 min. The structural change of the dentin collagen network with collagenase exposure was investigated by AFM and SEM at different time-points. The variations in surface/bulk mechanical properties and biodegradation resistance were characterized by nano-indentation, conventional mechanical testing, and hydroxyproline liberation at different time-points. Chemical changes associated with riboflavin/collagen-matrix interaction were analyzed by micro-Raman spectroscopy. UVA-activated riboflavin increased the mechanical properties, mechanical stability, and biodegradation resistance of the dentin collagen matrix. Higher collagen-network structural resistance against collagenolytic challenges was found with crosslinking. micro-Raman spectroscopy showed a strong dependency, in both intensity and wave-number, of certain Raman bands (1242-1667 cm(-1)) with crosslinking indicating the collagen/riboflavin interactions. UVA-activated riboflavin (1%) more efficiently crosslinked the dentin collagen matrix within a relatively clinically acceptable time-frame compared with 0.1% riboflavin.

  11. Analytical method to estimate resin cement diffusion into dentin

    NASA Astrophysics Data System (ADS)

    de Oliveira Ferraz, Larissa Cristina; Ubaldini, Adriana Lemos Mori; de Oliveira, Bruna Medeiros Bertol; Neto, Antonio Medina; Sato, Fracielle; Baesso, Mauro Luciano; Pascotto, Renata Corrêa

    2016-05-01

    This study analyzed the diffusion of two resin luting agents (resin cements) into dentin, with the aim of presenting an analytical method for estimating the thickness of the diffusion zone. Class V cavities were prepared in the buccal and lingual surfaces of molars (n=9). Indirect composite inlays were luted into the cavities with either a self-adhesive or a self-etch resin cement. The teeth were sectioned bucco-lingually and the cement-dentin interface was analyzed by using micro-Raman spectroscopy (MRS) and scanning electron microscopy. Evolution of peak intensities of the Raman bands, collected from the functional groups corresponding to the resin monomer (C-O-C, 1113 cm-1) present in the cements, and the mineral content (P-O, 961 cm-1) in dentin were sigmoid shaped functions. A Boltzmann function (BF) was then fitted to the peaks encountered at 1113 cm-1 to estimate the resin cement diffusion into dentin. The BF identified a resin cement-dentin diffusion zone of 1.8±0.4 μm for the self-adhesive cement and 2.5±0.3 μm for the self-etch cement. This analysis allowed the authors to estimate the diffusion of the resin cements into the dentin. Fitting the MRS data to the BF contributed to and is relevant for future studies of the adhesive interface.

  12. Methods for Biomimetic Remineralization of Human Dentine: A Systematic Review

    PubMed Central

    Cao, Chris Ying; Mei, May Lei; Li, Quan-Li; Lo, Edward Chin Man; Chu, Chun Hung

    2015-01-01

    This study aimed to review the laboratory methods on biomimetic remineralization of demineralized human dentine. A systematic search of the publications in the PubMed, TRIP, and Web of Science databases was performed. Titles and abstracts of initially identified publications were screened. Clinical trials, reviews, non-English articles, resin-dentine interface studies, hybrid layer studies, hybrid scaffolds studies, and irrelevant studies were excluded. The remaining papers were retrieved with full texts. Manual screening was conducted on the bibliographies of remaining papers to identify relevant articles. A total of 716 studies were found, and 690 were excluded after initial screening. Two articles were identified from the bibliographies of the remaining papers. After retrieving the full text, 23 were included in this systematic review. Sixteen studies used analogues to mimic the functions of non-collagenous proteins in biomineralization of dentine, and four studies used bioactive materials to induce apatite formation on demineralized dentine surface. One study used zinc as a bioactive element, one study used polydopamine, and another study constructed an agarose hydrogel system for biomimetic mineralization of dentine. Many studies reported success in biomimetic mineralization of dentine, including the use of non-collagenous protein analogues, bioactive materials, or elements and agarose hydrogel system. PMID:25739078

  13. Effect of solvents on bonding to root canal dentin.

    PubMed

    Erdemir, Ali; Eldeniz, Ayce Unverdi; Belli, Sema; Pashley, David H

    2004-08-01

    The long-term success of resin cementation of post/cores is likely increased with improvement in resin-root canal dentin bonding. The adverse effect of some irrigation constituents (NaOCl, H2O2) or medications (eugenol) on the bond strengths of resins to dentin have been reported. The purpose of this in vitro study was to evaluate the effect of two gutta-percha solvents (chloroform versus halothane) on microtensile bond strength to root canal dentin. Thirty, extracted, human, single-rooted teeth were instrumented to a #70 file and randomly divided into 3 groups of 10 each. The root canals were treated with water, chloroform, or halothane for 60 s. All root canals were obturated using C&B Metabond. After 24 h of storage in distilled water, serial 1-mm-thick cross-sections were cut and trimmed. Microtensile bond strength to apical, middle, and coronal root canal dentin were measured using an Instron machine. Using pooled data, the results indicated that water-treated roots had significantly higher resin-dentin bond strengths compared with chloroform or halothane treatment groups (control: 23.9 MPa; chloroform: 18.3 MPa; halothane: 17 MPa; p < 0.05). Gutta-percha solvents have an adverse effect on bond strengths of adhesive cements to root canal dentin.

  14. Methods for biomimetic remineralization of human dentine: a systematic review.

    PubMed

    Cao, Chris Ying; Mei, May Lei; Li, Quan-Li; Lo, Edward Chin Man; Chu, Chun Hung

    2015-03-02

    This study aimed to review the laboratory methods on biomimetic remineralization of demineralized human dentine. A systematic search of the publications in the PubMed, TRIP, and Web of Science databases was performed. Titles and abstracts of initially identified publications were screened. Clinical trials, reviews, non-English articles, resin-dentine interface studies, hybrid layer studies, hybrid scaffolds studies, and irrelevant studies were excluded. The remaining papers were retrieved with full texts. Manual screening was conducted on the bibliographies of remaining papers to identify relevant articles. A total of 716 studies were found, and 690 were excluded after initial screening. Two articles were identified from the bibliographies of the remaining papers. After retrieving the full text, 23 were included in this systematic review. Sixteen studies used analogues to mimic the functions of non-collagenous proteins in biomineralization of dentine, and four studies used bioactive materials to induce apatite formation on demineralized dentine surface. One study used zinc as a bioactive element, one study used polydopamine, and another study constructed an agarose hydrogel system for biomimetic mineralization of dentine. Many studies reported success in biomimetic mineralization of dentine, including the use of non-collagenous protein analogues, bioactive materials, or elements and agarose hydrogel system.

  15. Inhibition of endogenous dentin matrix metalloproteinases by ethylenediaminetetraacetic acid

    PubMed Central

    Thompson, J.M.; Agee, K.; Sidow, S.; McNally, K.; Lindsey, K.; Borke, J.; Elsalanty, M.; Tay, F.R.; Pashley, D.H.

    2011-01-01

    Introduction Endogenous dentin matrix metalloproteinases (MMPs) contribute to extracellular collagen matrix degradation in hybrid layers following adhesive dentin bonding procedures. Endodontic irrigants, including chlorhexidine (CHX) and ethylenediaminetetraacetic acid (EDTA) may help protect the hybrid layer from this process. The objective of the present study was to determine the exposure time necessary for EDTA to inactivate endogenous MMP activity in human dentin. Methods Dentin beams (2×1×3 mm) were prepared from mid-coronal dentin of extracted third molars. The beams were demineralized in 10 wt% phosphoric acid which also activated endogenous MMPs, and were divided into four experimental groups based on exposure time to 17% EDTA (0, 1, 2 or 5 min). A generic colorimetric MMP assay measured MMP activity via absorbance at 412 nm. Data were evaluated by Kruskal Wallis ANOVA, followed by Dunn’s pair-wise comparisons at α = 0.05. Results All exposure times resulted in significant inhibition (P<0.001) compared to unexposed controls. Specifically, percent inhibition for 1-, 2-, and 5-minute exposure times were 55.1±21.5%, 72.8±11.7%, and 74.7±19.7%, respectively. Conclusions 17% EDTA significantly inhibits endogenous MMP activity of human dentin within 1–2 min. This may minimize hybrid layer degradation following resin bonding procedures in the root canal space. PMID:22152622

  16. Short term exposure to elevated levels of leptin reduces proximal tubule cell metabolic activity.

    PubMed

    Briffa, Jessica F; Grinfeld, Esther; McAinch, Andrew J; Poronnik, Philip; Hryciw, Deanne H

    2014-01-25

    Leptin plays a pathophysiological role in the kidney, however, its acute effects on the proximal tubule cells (PTCs) are unknown. In opossum kidney (OK) cells in vitro, Western blot analysis identified that exposure to leptin increases the phosphorylation of the mitogen-activated protein kinase (MAPK) p44/42 and the mammalian target of rapamycin (mTOR). Importantly leptin (0.05, 0.10, 0.25 and 0.50 μg/ml) significantly reduced the metabolic activity of PTCs, and significantly decreased protein content per cell. Investigation of the role of p44/42 and mTOR on metabolic activity and protein content per cell, demonstrated that in the presence of MAPK inhibitor U0126 and mTOR inhibitor Ku-63794, that the mTOR pathway is responsible for the reduction in PTC metabolic activity in response to leptin. However, p44/42 and mTOR play no role the reduced protein content per cell in OKs exposed to leptin. Therefore, leptin modulates metabolic activity in PTCs via an mTOR regulated pathway.

  17. The effects of tooth preparation cleansing protocols on the bond strength of self-adhesive resin luting cement to contaminated dentin.

    PubMed

    Chaiyabutr, Yada; Kois, John C

    2008-01-01

    This in vitro study evaluated the bond strength of a self-adhesive luting cement after using four different techniques to remove surface contamination on dentin. Extracted human molars were flattened to expose the dentin surface and prepared for full crown preparation. Acrylic temporary crowns were fabricated and placed using temporary cement. The specimens were stored at room temperature with 100% relative humidity for seven days. Following removal of the temporary crowns, the specimens were randomly divided into four groups, and excess provisional cement was removed with (1) a hand instrument (excavator), (2) prophy with a mixture of flour pumice and water (3) aluminous oxide abrasion with a particle size of 27 microm at 40 psi and (4) aluminous oxide abrasion with a particle size of 50 microm at 40 psi. The microstructure morphology of the tooth surface was evaluated and residual materials were detected using SEM and EDS analysis of randomly selected specimens. The ceramics were treated with 9.5% hydrofluoric acid-etch and silanized to the prepared dentin prior to cementing with self-adhesive resin cement (RelyX Unicem, 3M ESPE). The shear bond strength was determined at a crosshead speed of 0.5 mm/minute. The results were analyzed with one-way ANOVA, followed by Tukey's test. Particle abrasion treatment of dentin with an aluminous oxide particle provided the highest values of bond strength, while hand instrument excavation was the lowest (p < 0.05). Aluminous oxide particle size did not significantly influence the bond strength at 40 psi. The use of low pressure and small particle abrasion treated dentin as a mechanical cleansing protocol prior to definitive cementation increased the bond strength of self-adhesive resin-luting cement to dentin following eugenol-containing temporary cement.

  18. The effects of host derived metalloproteinases on dentin bond and the role of MMPs inhibitors on dentin matrix degradation

    PubMed Central

    LONGHI, M.; CERRONI, L.; CONDÒ, S.G.; ARIANO, V.; PASQUANTONIO, G.

    2014-01-01

    SUMMARY Objectives. The work has the objective to analyze the literature on the degradation of the adhesive interface. In particular the study is focused on the role of the metalloproteinase in the hydrolytic degradation of collagen matrix in the bonded interface. The survey will concern also the latest innovations to improve and increase the link between dentin and the restorative materials through the MMPs inhibitors. Methods. The research has been carried out in the MEDLINE database by choosing keywords as “metalloproteinases” and “dentin bond” and “degradation”. In vitro studies were included in the research, excluding studies with no human and deciduous teeth. Language was limited to English. Results. The collagenolytic enzymes in mineralized dentin have been demonstrated to have an important role in dental hard tissue pathologies, including the degradation of the hybrid layer. Conclusion. The preservation of the collagen matrix integrity is a key issue in the attempts to improve the dentin bonding durability. PMID:25992261

  19. Effect of silver diamine fluoride on microtensile bond strength to dentin.

    PubMed

    Quock, R L; Barros, J A; Yang, S W; Patel, S A

    2012-01-01

    The aim of this in vitro study was to investigate the effect of the cariostatic and preventive agent silver diamine fluoride (SDF) on the microtensile bond strength of resin composite to dentin. Forty-two caries-free, extracted molars were flattened occlusally and apically using a diamond saw, and the exposed occlusal dentin was polished with a series of silicon carbide papers, all under water irrigation. The teeth were then randomly divided into six groups of seven teeth each that were treated as follows: 1) Peak SE self-etch bonding agent; 2) 12% SDF + Peak SE; 3) 38% SDF + Peak SE; 4) Peak LC etch-and-rinse bonding agent; 5) 12% SDF + Peak LC; and 6) 38% SDF + Peak LC. Four-millimeter buildups of Amelogen Plus were incrementally placed on all teeth; after a 24-hour storage period in distilled water, the specimens were sectioned perpendicular to the adhesive interface to produce beams of cross-sectional surface area measuring approximately 1 mm(2). The beams were placed on a microtensile testing machine, which utilized a single-speed pump motor and force gauge at 20 kgf × 0.01 second to record maximum tensile force before failure occurred. Two-way analysis of variance and post hoc Tukey tests were performed to compare the effects of the SDF on microtensile bond strength, with statistical significance set at α = 0.05. None of the experimental groups treated with different concentrations of SDF showed a significant difference in bond strength compared to the control groups, and there was no significant difference in bond strength between self-etch and etch-and-rinse groups. However, the effect of SDF on self-etch bonded teeth compared to etch-and-rinse bonded teeth was statistically significant (p=0.0363), specifically at the 12% concentration. SDF does not adversely affect the bond strength of resin composite to noncarious dentin.

  20. Long-term chlorhexidine effect on bond strength to Er:YAG laser irradiated-dentin.

    PubMed

    Galafassi, Daniel; Scatena, Camila; Colucci, Vivian; Rodrigues-Júnior, Antonio Luiz; Campos Serra, Mônica; Corona, Silmara Aparecida Milori

    2014-01-01

    This study evaluates the bond strength of dentin prepared with Er:YAG laser or bur, after rewetting with chlorhexidine on long-term artificial saliva storage and thermocycling. One hundred and twenty human third molars were sectioned in order to expose the dentin surface (n = 10). The specimens were randomly divided in 12 groups according to treatment and aging: Er:YAG laser rewetting with deionized water (LW) and 24 h storage in artificial saliva (WC); LW and 6 months of artificial saliva storage + 12.000 thermocycling (6M), LW and 12 months of artificial saliva storage + 24.000 thermocycling (12M), Er:YAG laser rewetting with 2% chlorhexidine (LC) and WC, LC and 6M, LC and 12M, bur on high-speed turbine rewetting with deionized water (TW) and WC, TW6M, TW12M, bur on high-speed turbine + 2% chlorhexidine (TC) and WC, TC and 6M, TC and 12M. The specimens were etched with 35% phosphoric acid, washed, and dried with air. Single Bond 2 adhesive was applied and the samples were restored with a composite. Each tooth was sectioned in order to obtain 4 sticks, which were submitted to microtensile bond strength test (µTBS). The two-way ANOVA, showed no significant differences for the interaction between the factors and for the aging factor. Tukey 5% showed that the LC group had the lowest µTBS. The rewetting with chlorhexidine negatively influenced the bond strength of the preparation with the Er:YAG laser. The artificial saliva aging and thermocycling did not interfere with dentin bond strength.

  1. Structural and Morphological Changes in Human Dentin after Ablative and Subablative Er:YAG Laser Irradiation

    PubMed Central

    Moosavi, Horieh; Ghorbanzadeh, Sajedeh; Ahrari, Farzaneh

    2016-01-01

    Introduction: This study investigated the influence of Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser on microhardness, chemical composition and subsurface morphology of dentin cavity walls. Methods: Forty sound human premolars were selected and randomly assigned into four groups. Class V cavities were prepared either with an Er:YAG laser (groups 1 and 2; 15 Hz, 250 mJ for enamel, 10 Hz, 200 mJ for dentin) or with a high speed handpiece (groups 3 and 4). The specimens in groups 1 and 3 served as the control, whereas those in groups 2 and 4 were exposed to subablative laser irradiation following cavity preparation (10 Hz, 50 mJ). After bisecting the specimens, one half was subjected to microhardness assessment and the other half was evaluated by SEM-EDS analysis. Results: Microhardness was significantly greater in the specimens prepared by both ablative and subablative laser irradiation (group 2) than that of the bur-prepared cavities (groups 3 and 4) (P < 0.05). The quantity of calcium ion was significantly greater in cavities prepared by the Er:YAG laser (groups 1 and 2) compared to that of the bur cavities (groups 3 and 4) (P < 0.05). Subablative irradiation improved microhardness and weight percentage of calcium ion in both laser and bur cavities, but the difference was not significant compared to that of the relevant control group (P > 0.05). Conclusion: Cavity preparation with an Er:YAG laser could be considered as an alternative to the conventional method of drilling, as it enhances the mechanical and compositional properties of lased dentin, especially when combined by subablative irradiation. PMID:27330703

  2. The effect of saliva decontamination procedures on dentin bond strength after universal adhesive curing

    PubMed Central

    Kim, Jayang; Hong, Sungok; Choi, Yoorina

    2015-01-01

    Objectives The purpose of this study was to investigate the effectiveness of multiple decontamination procedures for salivary contamination after curing of a universal adhesive on dentin bond strength according to its etch modes. Materials and Methods Forty-two extracted bovine incisors were trimmed by exposing the labial dentin surfaces and embedded in cylindrical molds. A universal adhesive (All-Bond Universal, Bisco) was used. The teeth were randomly divided into groups according to etch mode and decontamination procedure. The adhesive was applied according to the manufacturer's instructions for a given etch mode. With the exception of the control groups, the cured adhesive was contaminated with saliva for 20 sec. In the self-etch group, the teeth were divided into three groups: control, decontamination with rinsing and drying, and decontamination with rinsing, drying, and adhesive. In the etch-and-rinse group, the teeth were divided into four groups: control, decontamination with rinsing and drying, decontamination with rinsing, drying, and adhesive, and decontamination with rinsing, drying, re-etching, and reapplication of adhesive. A composite resin (Filtek Z350XT, 3M ESPE) was used for filling and was cured on the treated surfaces. Shear bond strength was measured, and failure modes were evaluated. The data were subjected to one-way analysis of variation and Tukey's HSD test. Results The etch-and-rinse subgroup that was decontaminated by rinse, drying, re-etching, and reapplication of adhesive showed a significantly higher bond strength. Conclusions When salivary contamination occurs after curing of the universal adhesive, additional etching improves the bond strength to dentin. PMID:26587416

  3. Effect of adhesive layers on microshear bond strength of nanocomposite resin to dentin

    PubMed Central

    Ebrahim, Mohamed I.

    2017-01-01

    Background Bond strength of adhesive layer can absorb unwanted stresses of polymerization shrinkage in composite resin restorations; increased microshear bond strength can prevent failure of restoration materials, the purpose of this study was to evaluate the effect of adhesive layers on microshear bond strength of nanocomposite resin to dentin. Material and Methods Two different types of adhesive systems: universal adhesive (ExciTE) and newly developed adhesive (Nano-Bond), and one type of light-cured resin restorative material (Nanocomposite resin) were used in this study. The occlusal surfaces of extracted human molar teeth were ground perpendicular to the long axis of each tooth to expose a flat dentin surface. The adhesives were applied on dentin surfaces (single application or double application). Nanocomposite resin was then placed and light cured for 40 seconds. After 24 hours of immersion in water at 37°C, then subjected to thermocycling before testing, a microshear bond test was carried out. The data were analyzed by a two-way ANOVA. For comparison between groups, Tukey’s post-hoc test was used. Results The mean bond strengths of ExciTE and Nano-Bond adhesives with a single application were 8.8 and 16.6 MPa, respectively. The mean bond strengths of ExciTE and Nano-Bond adhesives with double application were 13.2 and 21.8MPa, respectively. There were no statistically significant differences in microshear bond strengths between the single application of Nano-Bond and the double application of ExciTE adhesives. Conclusions Microshear bond strength increased significantly as the applied adhesive layer was doubled. Key words:Adhesive, microshear, bond, strength, nanocomposite. PMID:28210433

  4. Interaction morphology and bond strength of nanofilled simplified-step adhesives to acid etched dentin

    PubMed Central

    Di Hipólito, Vinicius; Reis, André Figueiredo; Mitra, Sumita B.; de Goes, Mario Fernando

    2012-01-01

    Objective: To evaluate the effect of nanofillers incorporated into adhesives on the microtensile bond strength (μ-TBS) and interfacial micromorphology to dentin. Methods: The occlusal enamel of 5 human molars was removed and each tooth sectioned into four quarters. The exposed dentin was treated with one of the following adhesives: Adper Single Bond (SB-unfilled), OptiBond Solo Plus (OS-barium aluminoborosilicate, 400nm Ø), Prime & Bond NT (NT-colloidal silica, 7–40 nm Ø) and Adper Single Bond 2 (SB2-colloidal silica, 5nm Ø). Cylinders of resin-based composite were constructed on the adhesive layers. After 24-hour storage, the restored tooth-quadrants were sectioned to obtain stick-shaped specimens (0.8 mm2, cross-sectional area) and submitted to μ-TBS at a cross-speed of 0.5 mm/min. Data were analyzed using one-way ANOVA and Tukey’s test (alpha = .05). Twenty-eight additional teeth were used for interfacial micro-morphologic analysis by SEM (16-teeth) and TEM (12-teeth). The dentin surfaces of 32 discs were treated with the adhesives (8 discs for adhesive) and laminated to form disc-pairs using a flowable resin composite for SEM/EDS analysis. For TEM, 90nm-thick nondemineralized unstained sections were processed. Results: SB2 showed significant higher bond strength than SB, OS and NT. The SEM/EDS and TEM analysis revealed nanofillers infiltrated within the interfibrillar spaces of the SB2-hybrid layer. Fillers were concentrated around patent tubular orifices and in the adhesive layer for OS and NT. Conclusion: The presence of nanofillers within the interfibrillar spaces of the SB2-hybrid layer suggests its importance in the improvement of the μ-TBS. PMID:23077413

  5. How erosive drinks and enzyme inhibitors impact bond strength to dentin.

    PubMed

    Machado, Camila Moreira; Zamuner, Aline Cristina; Modena, Karin Cristina da Silva; Ishikiriama, Sérgio Kiyoshi; Wang, Linda

    2015-01-01

    Concern has been raised about the bonding of restorative procedures to an erosive lesion, given the change in organic and inorganic composition and structure of this substrate. This in vitro study evaluated the effect of erosive drinks and an enzyme inhibitor (2% chlorhexidine digluconate - 2% CHX) on bond strength to dentin. Sixty sound human third molars were selected, and the occlusal enamel was flattened, exposing the dentin surface. The specimens were randomly divided into three groups: AS-Artificial saliva (control group), RC- Regular Cola and ZC- Zero Cola. Twenty specimens were immersed in their respective solution for 1 minute, 3 times a day, over the course of 5 days. After acid etching and before bonding with Adper Single Bond 2, half of the samples of each group (n = 10) were treated with 2% CHX, whereas the other half (n = 10) were not, forming the control group (CONV). All the specimens were restored with Filtek Z250 composite resin filled in Tygon tubes (0.48 mm2), yielding six microcylinders for microshear bond strength testing. Three composite resin microcylinders of each specimen were tested after 1 month, and the remaining microcylinders were tested after 6 months. Failure modes were determined using a stereomicroscope (40x). The data were statistically analyzed by three-way ANOVA and Tukey tests (α = 0.05). Overall bonding was reduced after 6 months, regardless of treatment. The 2% CHX enhanced bond strength after 1 month only in the ZC group, and did not enhance bonding performance to demineralized dentin by erosive protocol after 6 months in any group.

  6. The effect of washing water temperature on resin-dentin micro-shear bond strength

    PubMed Central

    Malekipour, Mohammad Reza; Shirani, Farzaneh; Ebrahimi, Mehrnoush

    2016-01-01

    Background: The purpose of this study was to evaluate the effect of washing water temperature on the micro-shear bond strength (μSBS) of composite resin to dentin using a two-step etch-and-rinse system and a two-step self-etching system. Materials and Methods: In this in vitro study, the intact dentins of buccal and lingual surfaces of healthy third molars were exposed. Dentin surfaces were rinsed with different temperatures of distilled water (20 s) before applying Single Bond (SB) or Clearfil SE Bond(SE). After applying the adhesive, composite cylinders (0.8 mm diameter and 1 mm length) were bonded to the teeth surfaces. After storing the specimens in 37°C distilled water for 48 h and thermocycling, μSBS test was done. Data were analyzed using analysis of variance, post hoc Tukey tests, paired samples t-test, and Fisher exact test (α = 0.05). Results: Temperature and interaction of temperature and type of bonding agent affected the bond strength. The bond strength of SB groups was significantly higher at 50°C washing than 5°C (P = 0.003) and 22°C (P = 0.019), but no significant difference was observed between SE groups. The bond strength of SE was significantly higher at 22°C than that of SB (P = 0.031), whereas the bond strength of SB was significantly higher at 50°C than that of SE (P = 0.007). Conclusion: The use of high-temperature washing water is an appropriate method to enhance bond strength in etch-and-rinse systems. PMID:27076833

  7. Importance of adenosine triphosphate in phospholipase A2-induced rabbit renal proximal tubule cell injury.

    PubMed Central

    Nguyen, V D; Cieslinski, D A; Humes, H D

    1988-01-01

    The pathogenesis of ischemic renal tubular cell injury involves a complex interaction of different processes, including membrane phospholipid alterations and depletion of high-energy phosphate stores. To assess the role of membrane phospholipid changes due to activation of phospholipases in renal tubule cell injury, suspensions enriched in rabbit renal proximal tubule segments were incubated with exogenous phospholipase A2 (PLA2). Exogenous PLA2 did not produce any significant change in various metabolic parameters reflective of cell injury in control nonhypoxic preparations despite a significant decrease in phosphatidylethanolamine (PE) and moderate increases in lysophosphatidylcholine (LPC) and lysophosphatidylethanolamine (LPE). In contrast, exogenous PLA2 treatment of hypoxic tubules resulted in a severe degree of cell injury, as demonstrated by marked declines in tubule K+ and ATP contents and significant decreases in tubule uncoupled respiratory rates, and was associated with significant phospholipid alterations, including marked declines in phosphatidylcholine (PC) and PE and significant rises in LPC, LPE, and free fatty acids (FFA). The injurious metabolic effects of exogenous PLA2 on hypoxic tubules were reversed by addition of ATP-MgCl2 to the tubules. The protective effect of ATP-MgCl2 was associated with increases in tubule PC and PE contents and declines in LPC, LPE, and FFA contents. These experiments thus indicate that an increase in exogenous PLA2 activity produces renal proximal tubule cell injury when cell ATP levels decline, at which point phospholipid resynthesis cannot keep pace with phospholipid degradation with resulting depletion of phospholipids and accumulation of lipid by-products. High-energy phosphate store depletion appears to be an important condition for exogenous PLA2 activity to induce renal tubule cell injury. PMID:3417866

  8. Protective effect of exper