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Sample records for dental enamel solubility

  1. Calcium solubility of dental enamel following Er, Cr:YSGG laser irradiation

    NASA Astrophysics Data System (ADS)

    Apel, Christian; Graeber, Hans-Georg; Gutknecht, Norbert

    2000-03-01

    Ever since the laser was introduced in dental medicine, there has been a constant discussion about its use in caries prevention. Various studies have already illustrated the possible uses of CO2 and argon lasers in this field of dentistry. The aim of the present study was to examine the Er,Cr:YSGG laser with regard to potential in reducing the acid solubility of dental enamel. Thirty freshly extracted bovine incisor teeth were prepared for this purpose. The crowns of the teeth were covered with hard wax, leaving a standardized test area free. The test specimens were then divided into three groups. The test area was uniformly irradiated with 2.7 J/cm2 in the first test group and 6.5 J/cm2 in the second test group. The third test group was left untreated (control group). Demineralization of the teeth was performed over a period of 24 hours in acetate buffer solution (0.1 mol/l) with a pH value of 4.5 and a temperature of 37 degrees Celsius. The calcium content of the solution was subsequently determined by flame photometry. The results confirm a significantly lower calcium content in the test group exposed to radiation of 6.5 J/cm2 (p less than 0.025). Dental enamel seems to have increased acid resistance following irradiation with the Er,Cr:YSGG laser.

  2. Dental Enamel Defects and Celiac Disease

    MedlinePlus

    ... Nutrition Home : Dental Enamel Defects and Celiac Disease Dental Enamel Defects and Celiac Disease Celiac disease manifestations ... affecting any organ or body system. One manifestation—dental enamel defects—can help dentists and other health ...

  3. Weaker dental enamel explains dental decay.

    PubMed

    Vieira, Alexandre R; Gibson, Carolyn W; Deeley, Kathleen; Xue, Hui; Li, Yong

    2015-01-01

    Dental caries continues to be the most prevalent bacteria-mediated non-contagious disease of humankind. Dental professionals assert the disease can be explained by poor oral hygiene and a diet rich in sugars but this does not account for caries free individuals exposed to the same risk factors. In order to test the hypothesis that amount of amelogenin during enamel development can influence caries susceptibility, we generated multiple strains of mice with varying levels of available amelogenin during dental development. Mechanical tests showed that dental enamel developed with less amelogenin is "weaker" while the dental enamel of animals over-expressing amelogenin appears to be more resistant to acid dissolution. PMID:25885796

  4. Dental enamel cells express functional SOCE channels

    PubMed Central

    Nurbaeva, Meerim K.; Eckstein, Miriam; Concepcion, Axel R.; Smith, Charles E.; Srikanth, Sonal; Paine, Michael L.; Gwack, Yousang; Hubbard, Michael J.; Feske, Stefan; Lacruz, Rodrigo S.

    2015-01-01

    Dental enamel formation requires large quantities of Ca2+ yet the mechanisms mediating Ca2+ dynamics in enamel cells are unclear. Store-operated Ca2+ entry (SOCE) channels are important Ca2+ influx mechanisms in many cells. SOCE involves release of Ca2+ from intracellular pools followed by Ca2+ entry. The best-characterized SOCE channels are the Ca2+ release-activated Ca2+ (CRAC) channels. As patients with mutations in the CRAC channel genes STIM1 and ORAI1 show abnormal enamel mineralization, we hypothesized that CRAC channels might be an important Ca2+ uptake mechanism in enamel cells. Investigating primary murine enamel cells, we found that key components of CRAC channels (ORAI1, ORAI2, ORAI3, STIM1, STIM2) were expressed and most abundant during the maturation stage of enamel development. Furthermore, inositol 1,4,5-trisphosphate receptor (IP3R) but not ryanodine receptor (RyR) expression was high in enamel cells suggesting that IP3Rs are the main ER Ca2+ release mechanism. Passive depletion of ER Ca2+ stores with thapsigargin resulted in a significant raise in [Ca2+]i consistent with SOCE. In cells pre-treated with the CRAC channel blocker Synta-66 Ca2+ entry was significantly inhibited. These data demonstrate that enamel cells have SOCE mediated by CRAC channels and implicate them as a mechanism for Ca2+ uptake in enamel formation. PMID:26515404

  5. Mechanistic aspects of the interactions between fluoride and dental enamel.

    PubMed

    ten Cate, J M; Featherstone, J D

    1991-01-01

    For many years after the discovery of its caries preventive effect, fluoride was thought to be primarily active by lowering the solubility of the apatitic mineral phase of the dental hard tissues. Recent findings have shed new light on the mechanisms by which fluoride inhibits or delays dental caries. Fluoride present in the oral fluids alters the rate of the naturally occurring dissolution and reprecipitation processes at the tooth-oral fluid interface. Demineralization of enamel is inhibited by concentrations of fluoride in the sub-ppm range. Likewise, remineralization of incipient caries lesions (the earliest stage of enamel caries) is accelerated by trace amounts of fluoride. As these two processes comprise dental caries the physiological balance between hard tissue breakdown and repair is favorably shifted by fluoride. The driving force for both phenomena is thermodynamic, that is, fluorapatite or a fluoridated hydroxyapatite may form when fluoride is supplied at low concentrations. This article critically reviews the current information about tooth-fluoride interactions, both from laboratory and clinical studies. PMID:1892991

  6. Subpicosecond laser ablation of dental enamel

    NASA Astrophysics Data System (ADS)

    Rode, A. V.; Gamaly, E. G.; Luther-Davies, B.; Taylor, B. T.; Dawes, J.; Chan, A.; Lowe, R. M.; Hannaford, P.

    2002-08-01

    Laser ablation of dental enamel with subpicosecond laser pulses has been studied over the intensity range of (0.1-1.4) x1014 W/cm2 using 95 and 150 fs pulses at a pulse repetition rate of 1 kHz. The experimentally determined ablation threshold of 2.2plus-or-minus0.1 J/cm2 was in good agreement with theoretical predictions based on an electrostatic ablation model. The ablation rate increased linearly with the laser fluence for up to 15 times the ablation threshold. The absence of collateral damage was observed using optical and scanning electron microscopy. Pulpal temperature measurements showed an increase of about 10 degC during the 200 s course of ablation. However, air cooling at a rate of 5 l/min resulted in the intrapulpal temperature being maintained below the pulpal damage threshhold of 5.5 degC. The material removal rates for subpicosecond precision laser ablation of dental enamel are compared with other techniques.

  7. Dental materials. Amorphous intergranular phases control the properties of rodent tooth enamel.

    PubMed

    Gordon, Lyle M; Cohen, Michael J; MacRenaris, Keith W; Pasteris, Jill D; Seda, Takele; Joester, Derk

    2015-02-13

    Dental enamel, a hierarchical material composed primarily of hydroxylapatite nanowires, is susceptible to degradation by plaque biofilm-derived acids. The solubility of enamel strongly depends on the presence of Mg(2+), F(-), and CO3(2-). However, determining the distribution of these minor ions is challenging. We show—using atom probe tomography, x-ray absorption spectroscopy, and correlative techniques—that in unpigmented rodent enamel, Mg(2+) is predominantly present at grain boundaries as an intergranular phase of Mg-substituted amorphous calcium phosphate (Mg-ACP). In the pigmented enamel, a mixture of ferrihydrite and amorphous iron-calcium phosphate replaces the more soluble Mg-ACP, rendering it both harder and more resistant to acid attack. These results demonstrate the presence of enduring amorphous phases with a dramatic influence on the physical and chemical properties of the mature mineralized tissue. PMID:25678658

  8. Hair keratin mutations in tooth enamel increase dental decay risk

    PubMed Central

    Duverger, Olivier; Ohara, Takahiro; Shaffer, John R.; Donahue, Danielle; Zerfas, Patricia; Dullnig, Andrew; Crecelius, Christopher; Beniash, Elia; Marazita, Mary L.; Morasso, Maria I.

    2014-01-01

    Tooth enamel is the hardest substance in the human body and has a unique combination of hardness and fracture toughness that protects teeth from dental caries, the most common chronic disease worldwide. In addition to a high mineral content, tooth enamel comprises organic material that is important for mechanical performance and influences the initiation and progression of caries; however, the protein composition of tooth enamel has not been fully characterized. Here, we determined that epithelial hair keratins, which are crucial for maintaining the integrity of the sheaths that support the hair shaft, are expressed in the enamel organ and are essential organic components of mature enamel. Using genetic and intraoral examination data from 386 children and 706 adults, we found that individuals harboring known hair disorder–associated polymorphisms in the gene encoding keratin 75 (KRT75), KRT75A161T and KRT75E337K, are prone to increased dental caries. Analysis of teeth from individuals carrying the KRT75A161T variant revealed an altered enamel structure and a marked reduction of enamel hardness, suggesting that a functional keratin network is required for the mechanical stability of tooth enamel. Taken together, our results identify a genetic locus that influences enamel structure and establish a connection between hair disorders and susceptibility to dental caries. PMID:25347471

  9. Hair keratin mutations in tooth enamel increase dental decay risk.

    PubMed

    Duverger, Olivier; Ohara, Takahiro; Shaffer, John R; Donahue, Danielle; Zerfas, Patricia; Dullnig, Andrew; Crecelius, Christopher; Beniash, Elia; Marazita, Mary L; Morasso, Maria I

    2014-12-01

    Tooth enamel is the hardest substance in the human body and has a unique combination of hardness and fracture toughness that protects teeth from dental caries, the most common chronic disease worldwide. In addition to a high mineral content, tooth enamel comprises organic material that is important for mechanical performance and influences the initiation and progression of caries; however, the protein composition of tooth enamel has not been fully characterized. Here, we determined that epithelial hair keratins, which are crucial for maintaining the integrity of the sheaths that support the hair shaft, are expressed in the enamel organ and are essential organic components of mature enamel. Using genetic and intraoral examination data from 386 children and 706 adults, we found that individuals harboring known hair disorder-associated polymorphisms in the gene encoding keratin 75 (KRT75), KRT75(A161T) and KRT75(E337K), are prone to increased dental caries. Analysis of teeth from individuals carrying the KRT75(A161T) variant revealed an altered enamel structure and a marked reduction of enamel hardness, suggesting that a functional keratin network is required for the mechanical stability of tooth enamel. Taken together, our results identify a genetic locus that influences enamel structure and establish a connection between hair disorders and susceptibility to dental caries. PMID:25347471

  10. Dental Enamel Development: Proteinases and Their Enamel Matrix Substrates

    PubMed Central

    Bartlett, John D.

    2013-01-01

    This review focuses on recent discoveries and delves in detail about what is known about each of the proteins (amelogenin, ameloblastin, and enamelin) and proteinases (matrix metalloproteinase-20 and kallikrein-related peptidase-4) that are secreted into the enamel matrix. After an overview of enamel development, this review focuses on these enamel proteins by describing their nomenclature, tissue expression, functions, proteinase activation, and proteinase substrate specificity. These proteins and their respective null mice and human mutations are also evaluated to shed light on the mechanisms that cause nonsyndromic enamel malformations termed amelogenesis imperfecta. Pertinent controversies are addressed. For example, do any of these proteins have a critical function in addition to their role in enamel development? Does amelogenin initiate crystallite growth, does it inhibit crystallite growth in width and thickness, or does it do neither? Detailed examination of the null mouse literature provides unmistakable clues and/or answers to these questions, and this data is thoroughly analyzed. Striking conclusions from this analysis reveal that widely held paradigms of enamel formation are inadequate. The final section of this review weaves the recent data into a plausible new mechanism by which these enamel matrix proteins support and promote enamel development. PMID:24159389

  11. Uptake and retention of aluminum by dental enamel.

    PubMed

    Kleber, C J; Putt, M S

    1985-12-01

    The uptake, depth of penetration, and retention of aluminum (Al) in sound and acid-etched dental enamel were determined following in vitro applications of solutions containing 0.005 M or 0.037 M Al. Compared with controls, significant amounts of Al uptake (approximately 2000 to 6000 ppm) were detected in both sound and etched enamel, with significantly more Al deposited in the latter. Analysis of successive layers of treated enamel demonstrated that Al was located predominantly within the first 20 microns of surface enamel. Only slight reductions in Al retention occurred following one week of water-soaking or one minute of brushing with water or dentifrice, indicating that Al was firmly bound by enamel. PMID:3865947

  12. ON THE BRITTLENESS OF ENAMEL AND SELECTED DENTAL MATERIALS

    PubMed Central

    Park, S.; Quinn, J. B; Romberg, E.; Arola, D.

    2008-01-01

    Although brittle material behavior is often considered undesirable, a quantitative measure of “brittleness” is currently not used in assessing the clinical merits of dental materials. Objective To quantify and compare the brittleness of human enamel and common dental restorative materials used for crown replacement. Methods Specimens of human enamel were prepared from the 3rd molars of “young” (18≤age≤25) and “old” (50≤age) patients. The hardness, elastic modulus and apparent fracture toughness were characterized as a function of distance from the DEJ using indentation approaches. These properties were then used in estimating the brittleness according to a model that accounts for the competing dissipative processes of deformation and fracture. The brittleness of selected porcelain, ceramic and Micaceous Glass Ceramic (MGC) dental materials was estimated and compared with that of the enamel. Results The average brittleness of the young and old enamel increased with distance from the DEJ. For the old enamel the average brittleness increased from approximately 300 µm−1 at the DEJ to nearly 900 µm−1 at the occlusal surface. While there was no significant difference between the two age groups at the DEJ, the brittleness of the old enamel was significantly greater (and up to 4 times higher) than that of the young enamel near the occlusal surface. The brittleness numbers for the restorative materials were up to 90% lower than that of young occlusal enamel. Significance The brittleness index could serve as a useful scale in the design of materials used for crown replacement, as well as a quantitative tool for characterizing degradation in the mechanical behavior of enamel. PMID:18436299

  13. Towards enamel biomimetics: Structure, mechanical properties and biomineralization of dental enamel

    NASA Astrophysics Data System (ADS)

    Fong, Hanson Kwok

    Dental enamel is the most mineralized tissue in the human body. This bioceramic, composed largely of hydroxyapatite (HAp), is also one of the most durable tissues despite a lifetime of masticatory loading and bacterial attack. The biosynthesis of enamel, which occurs in physiological conditions is a complex orchestration of protein assembly and mineral formation. The resulting product is the hardest tissue in the vertebrate body with the longest and most organized arrangement of hydroxyapatite crystals known to biomineralizing systems. Detail understanding of the structure of enamel in relationship to its mechanical function and the biomineralization process will provide a framework for enamel regeneration as well as potential lessons in the design of engineering materials. The objective of this study, therefore, is twofold: (1) establish the structure-function relationship of enamel as well as the dentine-enamel junction (DEJ) and (2) determine the effect of proteins on the enamel biomineralization process. A hierarchy in the enamel structure was established by means of various microscopy techniques (e.g. SEM, TEM, AFM). Mechanical properties (hardness and elastic modulus) associated with the microstructural features were also determined by nanoindentation. Furthermore, the DEJ was found to have a width in the range of micrometers to 10s of micrometers with continuous change in structure and mechanical properties. Indentation tests and contact fatigue tests using a spherical indenter have revealed that the structural features in the enamel and the DEJ played important roles in containing crack propagation emanating from the enamel tissue. To further understand the effect of this protein on the biominerailzation process, we have studied genetically engineered animals that express altered amelogenin which lack the known self-assembly properties. This in vivo study has revealed that, without the proper self-assembly of the amelogenin protein as demonstrated by the

  14. Precision ablation of dental enamel using a subpicosecond pulsed laser.

    PubMed

    Rode, A V; Gamaly, E G; Luther-Davies, B; Taylor, B T; Graessel, M; Dawes, J M; Chan, A; Lowe, R M; Hannaford, P

    2003-12-01

    In this study we report the use of ultra-short-pulsed near-infrared lasers for precision laser ablation of freshly extracted human teeth. The laser wavelength was approximately 800nm, with pulsewidths of 95 and 150fs, and pulse repetition rates of 1kHz. The laser beam was focused to an approximate diameter of 50microm and was scanned over the tooth surface. The rise in the intrapulpal temperature was monitored by embedded thermocouples, and was shown to remain below 5 degrees C when the tooth was air-cooled during laser treatment. The surface preparation of the ablated teeth, observed by optical and electron microscopy, showed no apparent cracking or heat effects, and the hardness and Raman spectra of the laser-treated enamel were not distinguishable from those of native enamel. This study indicates the potential for ultra-short-pulsed lasers to effect precision ablation of dental enamel. PMID:14738125

  15. Recovery of Crystallographic Texture in Remineralized Dental Enamel

    PubMed Central

    Siddiqui, Samera; Anderson, Paul; Al-Jawad, Maisoon

    2014-01-01

    Dental caries is the most prevalent disease encountered by people of all ages around the world. Chemical changes occurring in the oral environment during the caries process alter the crystallography and microstructure of dental enamel resulting in loss of mechanical function. Little is known about the crystallographic effects of demineralization and remineralization. The motivation for this study was to develop understanding of the caries process at the crystallographic level in order to contribute towards a long term solution. In this study synchrotron X-ray diffraction combined with scanning electron microscopy and scanning microradiography have been used to correlate enamel crystallography, microstructure and mineral concentration respectively in enamel affected by natural caries and following artificial demineralization and remineralization regimes. In particular, the extent of destruction and re-formation of this complex structure has been measured. 2D diffraction patterns collected at the European Synchrotron Radiation Facility were used to quantify changes in the preferred orientation (crystallographic texture) and position of the (002) Bragg reflection within selected regions of interest in each tooth slice, and then correlated with the microstructure and local mineral mass. The results revealed that caries and artificial demineralization cause a large reduction in crystallographic texture which is coupled with the loss of mineral mass. Remineralization restores the texture to the original level seen in healthy enamel and restores mineral density. The results also showed that remineralization promotes ordered formation of new crystallites and growth of pre-existing crystallites which match the preferred orientation of healthy enamel. Combining microstructural and crystallographic characterization aids the understanding of caries and erosion processes and assists in the progress towards developing therapeutic treatments to allow affected enamel to regain

  16. Composition of enamel pellicle from dental erosion patients.

    PubMed

    Carpenter, G; Cotroneo, E; Moazzez, R; Rojas-Serrano, M; Donaldson, N; Austin, R; Zaidel, L; Bartlett, D; Proctor, G

    2014-01-01

    Oral health is dependent upon a thin mobile film of saliva on soft and hard tissues. Salivary proteins adhere to teeth to form the acquired enamel pellicle which is believed to protect teeth from acid erosion. This study investigated whether patients suffering diet-induced dental erosion had altered enamel pellicles. Thirty patients suffering erosion were compared to healthy age-matched controls. Subjects wore a maxillary splint holding hydroxyapatite and human enamel blocks for 1 h. The acquired enamel pellicle was removed from the blocks and compared to the natural incisor pellicle. Basic Erosive Wear Examination scores confirmed that dental erosion was present in erosion patients and absent from healthy age-matched controls. Erosion patients had half the amount of proteins (BCA assay) within the acquired pellicle forming on splint blocks compared to normal controls (p < 0.05). In particular, statherin, a calcium-binding protein, was 35% less abundant (p < 0.05). Calcium concentration within the acquired pellicle was also reduced by 50% in erosion patients (p < 0.001). In contrast, the natural pellicle on the incisor had similar amounts of total protein in erosion patients and healthy controls. In summary, the formation of new acquired pellicles on surfaces was reduced in erosion patients, which may explain their greater susceptibility to acid erosion of teeth. PMID:24603346

  17. Sea otter dental enamel is highly resistant to chipping due to its microstructure

    PubMed Central

    Ziscovici, Charles; Lucas, Peter W.; Constantino, Paul J.; Bromage, Timothy G.; van Casteren, Adam

    2014-01-01

    Dental enamel is prone to damage by chipping with large hard objects at forces that depend on chip size and enamel toughness. Experiments on modern human teeth have suggested that some ante-mortem chips on fossil hominin enamel were produced by bite forces near physiological maxima. Here, we show that equivalent chips in sea otter enamel require even higher forces than human enamel. Increased fracture resistance correlates with more intense enamel prism decussation, often seen also in some fossil hominins. It is possible therefore that enamel chips in such hominins may have formed at even greater forces than currently envisaged. PMID:25319817

  18. Sea otter dental enamel is highly resistant to chipping due to its microstructure.

    PubMed

    Ziscovici, Charles; Lucas, Peter W; Constantino, Paul J; Bromage, Timothy G; van Casteren, Adam

    2014-10-01

    Dental enamel is prone to damage by chipping with large hard objects at forces that depend on chip size and enamel toughness. Experiments on modern human teeth have suggested that some ante-mortem chips on fossil hominin enamel were produced by bite forces near physiological maxima. Here, we show that equivalent chips in sea otter enamel require even higher forces than human enamel. Increased fracture resistance correlates with more intense enamel prism decussation, often seen also in some fossil hominins. It is possible therefore that enamel chips in such hominins may have formed at even greater forces than currently envisaged. PMID:25319817

  19. Continuum damage modeling and simulation of hierarchical dental enamel

    NASA Astrophysics Data System (ADS)

    Ma, Songyun; Scheider, Ingo; Bargmann, Swantje

    2016-05-01

    Dental enamel exhibits high fracture toughness and stiffness due to a complex hierarchical and graded microstructure, optimally organized from nano- to macro-scale. In this study, a 3D representative volume element (RVE) model is adopted to study the deformation and damage behavior of the fibrous microstructure. A continuum damage mechanics model coupled to hyperelasticity is developed for modeling the initiation and evolution of damage in the mineral fibers as well as protein matrix. Moreover, debonding of the interface between mineral fiber and protein is captured by employing a cohesive zone model. The dependence of the failure mechanism on the aspect ratio of the mineral fibers is investigated. In addition, the effect of the interface strength on the damage behavior is studied with respect to geometric features of enamel. Further, the effect of an initial flaw on the overall mechanical properties is analyzed to understand the superior damage tolerance of dental enamel. The simulation results are validated by comparison to experimental data from micro-cantilever beam testing at two hierarchical levels. The transition of the failure mechanism at different hierarchical levels is also well reproduced in the simulations.

  20. Functions of KLK4 and MMP-20 in dental enamel formation

    PubMed Central

    Lu, Yuhe; Papagerakis, Petros; Yamakoshi, Yasuo; Hu, Jan C-C.; Bartlett, John D.; Simmer, James P.

    2009-01-01

    Two proteases are secreted into the enamel matrix of developing teeth. The early protease is enamelysin (MMP-20). The late protease is kallikrein 4 (KLK4). Mutations in MMP20 and KLK4 both cause autosomal recessive amelogenesis imperfecta, a condition featuring soft, porous enamel containing residual protein. MMP-20 is secreted along with enamel proteins by secretory stage ameloblasts. Enamel protein cleavage products accumulate in the space between the crystal ribbons, helping to support them. MMP-20 steadily cleaves accumulated enamel proteins, so their concentration decreases with depth. Kallikrein 4 is secreted by transition and maturation stage ameloblasts. KLK4 aggressively degrades the retained organic matrix following the termination of enamel protein secretion. The principle functions of MMP-20 and KLK4 in dental enamel formation are to facilitate the orderly replacement of organic matrix with mineral, generating an enamel layer that is harder, less porous, and unstained by retained enamel proteins. PMID:18627287

  1. Dental enamel growth, perikymata and hypoplasia in ancient tooth crowns.

    PubMed Central

    Hillson, S W

    1992-01-01

    This paper describes the hypoplastic defects commonly seen on the surface of ancient human tooth crowns, excavated from archaeological sites, and presents a new method for estimating the ages at which these defects were initiated during life. The method is based upon examination of microscopic incremental structures on the enamel surface and it is possible also to apply it to reconstruction of the sequence and timing of dental crown development. The method of examination is non-destructive and allows full use to be made of the large numbers of complete, unworn dentitions which are found amongst archaeological remains. Images Figure 1. Figure 4. PMID:1404194

  2. Enamel microabrasion for aesthetic management of dental fluorosis

    PubMed Central

    Pandey, Pallavi; Ansari, Afroz Alam; Moda, Preeti; Yadav, Madhulika

    2013-01-01

    Fluorosis has increased in recent times due to fluoridation of drinking water and addition of fluoride to various edible items, which leads to unaesthetic appearance of teeth visible at close quarters. The enamel microabrasion technique is a conservative method that improves the appearance of the teeth by restoring bright and superficial smoothness, without causing significant structural loss. The aim of this article is to describe an easy technique for managing mild to moderate dental fluorosis using Opalustre (Ultradent Products) microabrasion slurry. This conservative approach may be considered an interesting alternative to more invasive prosthetic techniques like composite resin restorations, ceramic veneers or crown fabrications. PMID:24121810

  3. Enamel microabrasion for aesthetic management of dental fluorosis.

    PubMed

    Pandey, Pallavi; Ansari, Afroz Alam; Moda, Preeti; Yadav, Madhulika

    2013-01-01

    Fluorosis has increased in recent times due to fluoridation of drinking water and addition of fluoride to various edible items, which leads to unaesthetic appearance of teeth visible at close quarters. The enamel microabrasion technique is a conservative method that improves the appearance of the teeth by restoring bright and superficial smoothness, without causing significant structural loss. The aim of this article is to describe an easy technique for managing mild to moderate dental fluorosis using Opalustre (Ultradent Products) microabrasion slurry. This conservative approach may be considered an interesting alternative to more invasive prosthetic techniques like composite resin restorations, ceramic veneers or crown fabrications. PMID:24121810

  4. A new method of retrospective radiation dosimetry: Optically stimulated luminescence in dental enamel

    SciTech Connect

    Godfrey-Smith, D.I.; Pass, B.

    1997-05-01

    Currently, retrospective biophysical radiation dosimetry lacks a technique that is sensitive, non-invasive, and portable. This has made reliable cause and effect relationships between radiation exposure and its outcomes in humans difficult to establish. Since optical technology is amenable to miniaturization, a search for optically stimulated luminescence in dental enamel was begun. The first successful detection of time dependent optically stimulated luminescence from {gamma} irradiated enamel was accomplished. This luminescence is absent in enamel that is not irradiated or that was heated following irradiation. Thermoluminescence observations were made concurrently with the optical measurements which clarified the role of the organic component of enamel. 20 refs., 5 figs.

  5. Anisotropic constitutive model incorporating multiple damage mechanisms for multiscale simulation of dental enamel.

    PubMed

    Ma, Songyun; Scheider, Ingo; Bargmann, Swantje

    2016-09-01

    An anisotropic constitutive model is proposed in the framework of finite deformation to capture several damage mechanisms occurring in the microstructure of dental enamel, a hierarchical bio-composite. It provides the basis for a homogenization approach for an efficient multiscale (in this case: multiple hierarchy levels) investigation of the deformation and damage behavior. The influence of tension-compression asymmetry and fiber-matrix interaction on the nonlinear deformation behavior of dental enamel is studied by 3D micromechanical simulations under different loading conditions and fiber lengths. The complex deformation behavior and the characteristics and interaction of three damage mechanisms in the damage process of enamel are well captured. The proposed constitutive model incorporating anisotropic damage is applied to the first hierarchical level of dental enamel and validated by experimental results. The effect of the fiber orientation on the damage behavior and compressive strength is studied by comparing micro-pillar experiments of dental enamel at the first hierarchical level in multiple directions of fiber orientation. A very good agreement between computational and experimental results is found for the damage evolution process of dental enamel. PMID:27294283

  6. Function and repair of dental enamel - Potential role of epithelial transport processes of ameloblasts.

    PubMed

    Varga, Gábor; Kerémi, Beáta; Bori, Erzsébet; Földes, Anna

    2015-07-01

    The hardest mammalian tissue, dental enamel is produced by ameloblasts, which are electrolyte-transporting epithelial cells. Although the end product is very different, they show many similarities to transporting epithelia of the pancreas, salivary glands and kidney. Enamel is produced in a multi-step epithelial secretory process that features biomineralization which is an interplay of secreted ameloblast specific proteins and the time-specific transport of minerals, protons and bicarbonate. First, "secretory" ameloblasts form the entire thickness of the enamel layer, but with low mineral content. Then they differentiate into "maturation" ameloblasts, which remove organic matrix from the enamel and in turn further build up hydroxyapatite crystals. The protons generated by hydroxyapatite formation need to be buffered, otherwise enamel will not attain full mineralization. Buffering requires a tight pH regulation and secretion of bicarbonate by ameloblasts. The whole process has been the focus of many immunohistochemical and gene knock-out studies, but, perhaps surprisingly, no functional data existed for mineral ion transport by ameloblasts. However, recent studies including ours provided a better insight for molecular mechanism of mineral formation. The secretory regulation is not completely known as yet, but its significance is crucial. Impairing regulation retards or prevents completion of enamel mineralization and results in the development of hypomineralized enamel that easily erodes after dental eruption. Factors that impair this function are fluoride and disruption of pH regulators. Revealing these factors may eventually lead to the treatment of enamel hypomineralization related to genetic or environmentally induced malformation. PMID:25747281

  7. Near-IR and PS-OCT imaging of developmental defects in dental enamel

    NASA Astrophysics Data System (ADS)

    Hirasuna, Krista; Fried, Daniel; Darling, Cynthia L.

    2007-02-01

    Polarization sensitive optical coherence tomography (PS-OCT) and near-IR (NIR) imaging are promising new technologies under development for monitoring early carious lesions. Fluorosis is a growing problem in the U.S., and the more prevalent mild fluorosis can be visually mistaken for early enamel demineralization. Some initial NIR images suggest that enamel defects and dental caries manifest different optical behavior in the NIR. Unfortunately, there is little quantitative information available regarding the differences in optical properties of sound enamel, enamel developmental defects, and demineralized enamel due to caries. This study tested the hypothesis that hypomineralized enamel due to fluorosis can be differentiated from demineralized enamel due to caries using NIR and PS-OCT imaging because of different optical behavior in the NIR. Thirty extracted human teeth with various degrees of suspected fluorosis and/or caries were imaged using PS-OCT and NIR transillumination. An InGaAs camera and a near-IR diode laser were used to measure the optical attenuation through transverse tooth sections (~200 μm). Developmental defects were clearly visible in the polarization-resolved OCT images, demonstrating that PS-OCT can be used to nondestructively measure the depth and possible severity of the defects. Enamel defects on whole teeth that could be imaged with high contrast with visible light were transparent in the near-IR while demineralized areas due to caries were opaque. In contrast, dental caries could be clearly distinguished from sound enamel. This study suggests that PS-OCT and NIR methods may potentially be used as tools to assess the severity and extent of enamel defects and for the differentiation of mild fluorosis defects from early carious lesions.

  8. Distribution patterns of elements in dental enamel of G. blacki: a preliminary dietary investigation using SRXRF

    NASA Astrophysics Data System (ADS)

    Qu, Yating; Jin, Changzhu; Zhang, Yingqi; Hu, Yaowu; Shang, Xue; Wang, Changsui

    2013-04-01

    We measured the elemental mappings in dental enamel of Gigantopithecus blacki ( n=3) using synchrotron radiation X-ray fluorescence (SRXRF) to understand the dietary variation during the time of tooth eruption. In order to account for the effects of diagenesis on the variation of elements in these fossil teeth, we compared the Fe and Mn elemental distribution and levels in dental enamel of G. blacki with that of a single modern pig tooth and found no differences. The observation of the variations of Sr, Ca and RE (rare earth elements) distribution in the incremental lines reveals that the plant foods utilized by G. blacki from the early Pleistocene or the middle Pleistocene had varied during the formation of dental enamel, possibly caused by the change of living environment or food resources. The variations of elemental distribution in different incremental lines are very promising to understand the nutritional and physical stress of G. blacki during the tooth eruption and environmental adaptations.

  9. Physical model for non-steady-state dissolution of dental enamel.

    PubMed

    Patel, M V; Fox, J L; Higuchi, W I

    1987-09-01

    The purpose of this study was to provide a rigorous theoretical understanding of the dissolution behavior of dental enamel over the entire time-course of demineralization and to simulate by computer an erosion-type caries lesion according to the physical "hydroxyapatite model". The appropriate diffusion equations which account for simultaneous diffusion and equilibrium of all species in enamel pores, boundary layer, and bulk solution, and which also take into consideration surface reaction kinetics, were employed to allow for calculation of the micro-environmental solution concentration and changes in the mineral density as a function of time and distance within the enamel. This comprehensive physical model for non-steady-state enamel dissolution also explicitly takes into account changes in the diffusivity and the dissolution rate constant as a function of mineral density. Demineralization experiments were conducted in 0.1 mol/L sink acetate buffer (pH = 4.50, mu = 0.50), with ground bovine dental enamel blocks of known surface area mounted (with beeswax) in a rotating disk apparatus. Mineral density profiles were quantified by means of contact x-ray microradiography. The physical model was used to predict mineral density profiles for given demineralization treatments. The experimental profiles agreed quite well with the predicted profiles, when the effective diffusivity of the enamel was assumed to be a function of porosity and when changes in surface area of the crystallites were taken into consideration. PMID:3476613

  10. Effects of enamel abrasion, salivary pellicle, and measurement angle on the optical assessment of dental erosion

    NASA Astrophysics Data System (ADS)

    Lussi, Adrian; Bossen, Anke; Höschele, Christoph; Beyeler, Barbara; Megert, Brigitte; Meier, Christoph; Rakhmatullina, Ekaterina

    2012-09-01

    The present study assessed the effects of abrasion, salivary proteins, and measurement angle on the quantification of early dental erosion by the analysis of reflection intensities from enamel. Enamel from 184 caries-free human molars was used for in vitro erosion in citric acid (pH 3.6). Abrasion of the eroded enamel resulted in a 6% to 14% increase in the specular reflection intensity compared to only eroded enamel, and the reflection increase depended on the erosion degree. Nevertheless, monitoring of early erosion by reflection analysis was possible even in the abraded eroded teeth. The presence of the salivary pellicle induced up to 22% higher reflection intensities due to the smoothing of the eroded enamel by the adhered proteins. However, this measurement artifact could be significantly minimized (p<0.05) by removing the pellicle layer with 3% NaOCl solution. Change of the measurement angles from 45 to 60 deg did not improve the sensitivity of the analysis at late erosion stages. The applicability of the method for monitoring the remineralization of eroded enamel remained unclear in a demineralization/remineralization cycling model of early dental erosion in vitro.

  11. Effects of enamel abrasion, salivary pellicle, and measurement angle on the optical assessment of dental erosion.

    PubMed

    Lussi, Adrian; Bossen, Anke; Höschele, Christoph; Beyeler, Barbara; Megert, Brigitte; Meier, Christoph; Rakhmatullina, Ekaterina

    2012-09-01

    The present study assessed the effects of abrasion, salivary proteins, and measurement angle on the quantification of early dental erosion by the analysis of reflection intensities from enamel. Enamel from 184 caries-free human molars was used for in vitro erosion in citric acid (pH 3.6). Abrasion of the eroded enamel resulted in a 6% to 14% increase in the specular reflection intensity compared to only eroded enamel, and the reflection increase depended on the erosion degree. Nevertheless, monitoring of early erosion by reflection analysis was possible even in the abraded eroded teeth. The presence of the salivary pellicle induced up to 22% higher reflection intensities due to the smoothing of the eroded enamel by the adhered proteins. However, this measurement artifact could be significantly minimized (p<0.05) by removing the pellicle layer with 3% NaOCl solution. Change of the measurement angles from 45 to 60 deg did not improve the sensitivity of the analysis at late erosion stages. The applicability of the method for monitoring the remineralization of eroded enamel remained unclear in a demineralization/remineralization cycling model of early dental erosion in vitro. PMID:23085926

  12. Year of Birth Determination Using Radiocarbon Dating of Dental Enamel

    SciTech Connect

    Buchholz, B A; Spalding, K L

    2009-03-10

    Radiocarbon dating is typically an archaeological tool rather than a forensic one. Recently however, we have shown that the amount of radiocarbon present in tooth enamel, as a result of nuclear bomb testing during the cold war, is a remarkably accurate indicator of when a person is born. Enamel isolated from human teeth is processed to form graphite and carbon-14 ({sup 14}C) levels are measured using accelerator mass spectrometry. Since there is no turnover of enamel after it is formed, {sup 14}C levels in the enamel represent {sup 14}C levels in the atmosphere at the time of its formation. In this paper we describe the strategy used to determine the date of birth of an individual based on radiocarbon levels in tooth enamel, focusing on the methodology of this strategy. Year of birth information can significantly assist police investigators when the identity of a deceased individual is unknown. In such cases police will try to match particulars of the unidentified individual (which is often only gender and/or an estimate of age), with particulars from missing persons lists.

  13. Year of birth determination using radiocarbon dating of dental enamel

    PubMed Central

    Buchholz, B.A.; Spalding, K.L

    2010-01-01

    Radiocarbon dating is typically an archaeological tool rather than a forensic one. Recently however, we have shown that the amount of radiocarbon present in tooth enamel, as a result of nuclear bomb testing during the cold war, is a remarkably accurate indicator of when a person is born. Enamel isolated from human teeth is processed to form graphite and carbon-14 (14C) levels are measured using accelerator mass spectrometry. Since there is no turnover of enamel after it is formed, 14C levels in the enamel represent 14C levels in the atmosphere at the time of its formation. In this paper we describe the strategy used to determine the date of birth of an individual based on radiocarbon levels in tooth enamel, focusing on the methodology of this strategy. Year of birth information can significantly assist police investigators when the identity of a deceased individual is unknown. In such cases police will try to match particulars of the unidentified individual (which is often only gender and/or an estimate of age), with particulars from missing persons lists. PMID:20976120

  14. Year of birth determination using radiocarbon dating of dental enamel.

    PubMed

    Buchholz, B A; Spalding, K L

    2010-05-01

    Radiocarbon dating is typically an archaeological tool rather than a forensic one. Recently however, we have shown that the amount of radiocarbon present in tooth enamel, as a result of nuclear bomb testing during the cold war, is a remarkably accurate indicator of when a person is born. Enamel isolated from human teeth is processed to form graphite and carbon-14 ((14)C) levels are measured using accelerator mass spectrometry. Since there is no turnover of enamel after it is formed, (14)C levels in the enamel represent (14)C levels in the atmosphere at the time of its formation. In this paper we describe the strategy used to determine the date of birth of an individual based on radiocarbon levels in tooth enamel, focusing on the methodology of this strategy. Year of birth information can significantly assist police investigators when the identity of a deceased individual is unknown. In such cases police will try to match particulars of the unidentified individual (which is often only gender and/or an estimate of age), with particulars from missing persons lists. PMID:20976120

  15. Dental Enamel Irradiated with Infrared Diode Laser and Photo-Absorbing Cream: Part 2—EDX Study

    PubMed Central

    dos Santos, Edson Aparecido Pereira; Soares, Luís Eduardo Silva; do Espírito Santo, Ana Maria; Martin, Airton Abrahão; Duarte, Danilo Antônio; Pacheco-Soares, Cristina; Brugnera, Aldo

    2009-01-01

    Abstract Objective: The effects of laser-induced compositional changes on the enamel were investigated by energy-dispersive X-ray fluorescence spectrometry (μ-EDX). After cariogenic challenge, we administered treatment of low-level infrared diode laser and a photo-absorbing cream (used to intensify the superficial light absorption). Background Data: Dental caries is considered the most prevalent oral disease. A simple and noninvasive caries preventive regimen is treating tooth enamel with a laser, either alone or in combination with fluoride, which reduces enamel solubility and dissolution rates. High power lasers are still not widely used in private practice. Low-power near-infrared lasers may be an alternative approach. Energy-dispersive μ-EDX is a versatile and nondestructive spectroscopic technique that allows for a qualitative and quantitative elemental analysis of inorganic enamel components, such as calcium and phosphorus. Materials and Methods: Twenty-four extracted or exfoliated caries-free deciduous molars were divided into six groups: 1) control group (CTR-no treatment); 2) infrared laser treatment (L) (λ = 810 nm, 100 mW/cm2, 90 sec, 4.47 J/cm2, 9 J); 3) infrared laser irradiation and photo-absorbing agent (CL); 4) photo-absorbing agent alone (C); 5) infrared laser irradiation and fluoridated photo-absorbing agent (FCL); and 6) fluoridated photo-absorbing agent alone (FC). Samples were analyzed using μ-EDX after two sets of treatments and pH cycling cariogenic challenges. Results: The CL group showed statistically significant increases in calcium and phosphorus (wt%) compared with the CTR group. The Ca/P ratio was similar in the FCL and CTR groups. There was a significant laser-induced reduction compared with the CTR group, and there was a possible modification of the organic balance content in enamel treated with laser and cream. Conclusion: μ-EDX may be able to detect compositional changes in mineral phases of lased enamel under

  16. Matrix metalloproteinase-20 mediates dental enamel biomineralization by preventing protein occlusion inside apatite crystals.

    PubMed

    Prajapati, Saumya; Tao, Jinhui; Ruan, Qichao; De Yoreo, James J; Moradian-Oldak, Janet

    2016-01-01

    Reconstruction of enamel-like materials is a central topic of research in dentistry and material sciences. The importance of precise proteolytic mechanisms in amelogenesis to form a hard tissue with more than 95% mineral content has already been reported. A mutation in the Matrix Metalloproteinase-20 (MMP-20) gene results in hypomineralized enamel that is thin, disorganized and breaks from the underlying dentin. We hypothesized that the absence of MMP-20 during amelogenesis results in the occlusion of amelogenin in the enamel hydroxyapatite crystals. We used spectroscopy and electron microscopy techniques to qualitatively and quantitatively analyze occluded proteins within the isolated enamel crystals from MMP-20 null and Wild type (WT) mice. Our results showed that the isolated enamel crystals of MMP-20 null mice had more organic macromolecules occluded inside them than enamel crystals from the WT. The crystal lattice arrangements of MMP-20 null enamel crystals analyzed by High Resolution Transmission Electron Microscopy (HRTEM) were found to be significantly different from those of the WT. Raman studies indicated that the crystallinity of the MMP-20 null enamel crystals was lower than that of the WT. In conclusion, we present a novel functional mechanism of MMP-20, specifically prevention of unwanted organic material entrapped in the forming enamel crystals, which occurs as the result of precise amelogenin cleavage. MMP-20 action guides the growth morphology of the forming hydroxyapatite crystals and enhances their crystallinity. Elucidating such molecular mechanisms can be applied in the design of novel biomaterials for future clinical applications in dental restoration or repair. PMID:26513418

  17. Near-IR polarization imaging of sound and carious dental enamel

    NASA Astrophysics Data System (ADS)

    Darling, Cynthia L.; Jiao, Jane J.; Lee, Chulsung; Kang, Hobin; Fried, Daniel

    2010-02-01

    A thorough understanding of how polarized near-IR light propagates through sound and carious dental hard tissues is important for the development of dental optical imaging systems. New optical imaging tools for the detection and assessment of dental caries (dental decay) such as near-IR imaging and optical coherence tomography can exploit the enhanced contrast provided by polarization sensitivity. In this investigation, an automated system was developed to collect images for the full 16-element Mueller Matrix. The polarized light was controlled by linear polarizers and liquid crystal retarders and the 36 images were acquired as the polarized near-IR light propagates through the enamel of extracted human thin tooth sections. In previous work, we reported that polarized light is rapidly depolarized by demineralized enamel, and sound and demineralized dentin.1 The rapid depolarization of polarized light by dental caries in the near-IR provides high contrast for caries imaging and detection. In this initial study, major differences in the Mueller matrix elements were observed in both sound and demineralized enamel which supports this approach and warrants further investigation.

  18. Atomic-scale compositional mapping reveals Mg-rich amorphous calcium phosphate in human dental enamel.

    PubMed

    La Fontaine, Alexandre; Zavgorodniy, Alexander; Liu, Howgwei; Zheng, Rongkun; Swain, Michael; Cairney, Julie

    2016-09-01

    Human dental enamel, the hardest tissue in the body, plays a vital role in protecting teeth from wear as a result of daily grinding and chewing as well as from chemical attack. It is well established that the mechanical strength and fatigue resistance of dental enamel are derived from its hierarchical structure, which consists of periodically arranged bundles of hydroxyapatite (HAP) nanowires. However, we do not yet have a full understanding of the in vivo HAP crystallization process that leads to this structure. Mg(2+) ions, which are present in many biological systems, regulate HAP crystallization by stabilizing its precursor, amorphous calcium phosphate (ACP), but their atomic-scale distribution within HAP is unknown. We use atom probe tomography to provide the first direct observations of an intergranular Mg-rich ACP phase between the HAP nanowires in mature human dental enamel. We also observe Mg-rich elongated precipitates and pockets of organic material among the HAP nanowires. These observations support the postclassical theory of amelogenesis (that is, enamel formation) and suggest that decay occurs via dissolution of the intergranular phase. This information is also useful for the development of more accurate models to describe the mechanical behavior of teeth. PMID:27617291

  19. Atomic-scale compositional mapping reveals Mg-rich amorphous calcium phosphate in human dental enamel

    PubMed Central

    La Fontaine, Alexandre; Zavgorodniy, Alexander; Liu, Howgwei; Zheng, Rongkun; Swain, Michael; Cairney, Julie

    2016-01-01

    Human dental enamel, the hardest tissue in the body, plays a vital role in protecting teeth from wear as a result of daily grinding and chewing as well as from chemical attack. It is well established that the mechanical strength and fatigue resistance of dental enamel are derived from its hierarchical structure, which consists of periodically arranged bundles of hydroxyapatite (HAP) nanowires. However, we do not yet have a full understanding of the in vivo HAP crystallization process that leads to this structure. Mg2+ ions, which are present in many biological systems, regulate HAP crystallization by stabilizing its precursor, amorphous calcium phosphate (ACP), but their atomic-scale distribution within HAP is unknown. We use atom probe tomography to provide the first direct observations of an intergranular Mg-rich ACP phase between the HAP nanowires in mature human dental enamel. We also observe Mg-rich elongated precipitates and pockets of organic material among the HAP nanowires. These observations support the postclassical theory of amelogenesis (that is, enamel formation) and suggest that decay occurs via dissolution of the intergranular phase. This information is also useful for the development of more accurate models to describe the mechanical behavior of teeth. PMID:27617291

  20. Structure and scale of the mechanics of mammalian dental enamel viewed from an evolutionary perspective.

    PubMed

    Lucas, Peter W; Philip, Swapna M; Al-Qeoud, Dareen; Al-Draihim, Nuha; Saji, Sreeja; van Casteren, Adam

    2016-01-01

    Mammalian enamel, the contact dental tissue, is something of an enigma. It is almost entirely made of hydroxyapatite, yet exhibits very different mechanical behavior to a homogeneous block of the same mineral. Recent approaches suggest that its hierarchical composite form, similar to other biological hard tissues, leads to a mechanical performance that depends very much on the scale of measurement. The stiffness of the material is predicted to be highest at the nanoscale, being sacrificed to produce a high toughness at the largest scale, that is, at the level of the tooth crown itself. Yet because virtually all this research has been conducted only on human (or sometimes "bovine") enamel, there has been little regard for structural variation of the tissue considered as evolutionary adaptation to diet. What is mammalian enamel optimized for? We suggest that there are competing selective pressures. We suggest that the structural characteristics that optimize enamel to resist large-scale fractures, such as crown failures, are very different to those that resist wear (small-scale fracture). While enamel is always designed for damage tolerance, this may be suboptimal in the enamel of some species, including modern humans (which have been the target of most investigations), in order to counteract wear. The experimental part of this study introduces novel techniques that help to assess resistance at the nanoscale. PMID:26763592

  1. Synchrotron X-ray diffraction characterization of healthy and fluorotic human dental enamel

    NASA Astrophysics Data System (ADS)

    Colaço, M. V.; Barroso, R. C.; Porto, I. M.; Gerlach, R. F.; Costa, F. N.; Braz, D.; Droppa, R.; de Sousa, F. B.

    2012-10-01

    With the introduction of fluoride as the main anticaries agent used in preventive dentistry, and perhaps an increase in fluoride in our food chain, dental fluorosis has become an increasing world-wide problem. Visible signs of fluorosis begin to become obvious on the enamel surface as opacities, implying some porosity in the tissue. The mechanisms that conduct the formation of fluorotic enamel are unknown, but should involve modifications in the basic physical-chemistry reactions of demineralization and remineralisation of the enamel of the teeth, which is the same reaction of formation of the enamel's hydroxyapatite (HAp) in the maturation phase. The increase of the amount of fluoride inside of the apatite will result in gradual increase of the lattice parameters. The aim of this work is to characterize the healthy and fluorotic enamel in human tooth using Synchrotron X-ray diffraction. All the scattering profile measurements were carried out at the X-ray diffraction beamline (XRD1) at the Brazilian Synchrotron Light Laboratory—LNLS, Campinas, Brazil. X-ray diffraction experiments were performed both in powder samples and polished surfaces. The powder samples were analyzed to obtain the characterization of a typical healthy enamel pattern. The polished surfaces were analyzed in specific areas that have been identified as fluorotic ones. X-ray diffraction data were obtained for all samples and these data were compared with the control samples and also with the literature data.

  2. Trace elementary concentration in enamel after dental bleaching using HI-ERDA

    NASA Astrophysics Data System (ADS)

    Added, N.; Rizzutto, M. A.; Curado, J. F.; Francci, C.; Markarian, R.; Mori, M.

    2006-08-01

    Changes of elementary concentrations in dental enamel after a bleaching treatment with different products, is presented, with special focus on the oxygen contribution. Concentrations for Ca, P, O and C and some other trace elements were obtained for enamel of bovine incisor teeth by HI-ERDA measurements using a 35Cl incident beam and an ionization chamber. Five groups of teeth with five samples each were treated with a different bleaching agents. Each tooth had its crown sectioned in two halves, one for bleaching test and one the other used as a control. Average values of C/Ca, O/Ca, F/Ca enrichment factors were found. The comparison between bleached and non-bleached halves indicates that bleaching treatment did not affect the mineral structure when low-concentration whitening systems were used. The almost constant oxygen concentration in enamel, suggests little changes due to whitening therapy.

  3. AFM analysis of bleaching effects on dental enamel microtopography

    NASA Astrophysics Data System (ADS)

    Pedreira de Freitas, Ana Carolina; Espejo, Luciana Cardoso; Botta, Sergio Brossi; Teixeira, Fernanda de Sa; Luz, Maria Aparecida A. Cerqueira; Garone-Netto, Narciso; Matos, Adriana Bona; Salvadori, Maria Cecilia Barbosa da Silveira

    2010-02-01

    The purpose of this in vitro study was to test a new methodology to evaluate the effects of 35% hydrogen peroxide agent on the microtopography of sound enamel using an atomic force microscope (AFM). The buccal sound surfaces of three extracted human lower incisors were used, without polishing the surfaces to maintain them with natural morphology. These unpolished surfaces were subjected to bleaching procedure with 35% hydrogen peroxide that consisted of 4 applications of the bleaching agent on enamel surfaces for 10 min each application. Surface images were obtained in a 15 μm × 15 μm area using an AFM. The roughness (Ra and RMS) and the power spectral density (PSD) were obtained before and after the bleaching treatment. As results we could inquire that the PSD analyses were very suitable to identifying the morphological changes on the surfaces, while the Ra and RMS parameters were insufficient to represent the morphological alterations promoted by bleaching procedure on enamel. The morphological wavelength in the range of visible light spectrum (380-750 nm) was analyzed, showing a considerable increase of the PSD with the bleaching treatment.

  4. Optical characterization of one dental composite resin using bovine enamel as reinforcing filler

    NASA Astrophysics Data System (ADS)

    Tribioli, J. T.; Jacomassi, D.; Rastelli, A. N. S.; Pratavieira, S.; Bagnato, V. S.; Kurachi, C.

    2012-01-01

    The use of composite resins for restorative procedure in anterior and posterior cavities is highly common in Dentistry due to its mechanical and aesthetic properties that are compatible with the remaining dental structure. Thus, the aim of this study was to evaluate the optical characterization of one dental composite resin using bovine enamel as reinforcing filler. The same organic matrix of the commercially available resins was used for this experimental resin. The reinforcing filler was obtained after the gridding of bovine enamel fragments and a superficial treatment was performed to allow the adhesion of the filler particles with the organic matrix. Different optical images as fluorescence and reflectance were performed to compare the experimental composite with the human teeth. The present experimental resin shows similar optical properties compared with human teeth.

  5. Optical pen-size reflectometer for monitoring of early dental erosion in native and polished enamels.

    PubMed

    Rakhmatullina, Ekaterina; Bossen, Anke; Bachofner, Kai K; Meier, Christoph; Lussi, Adrian

    2013-11-01

    Application of the specular reflection intensity was previously reported for the quantification of early dental erosion. Further development of the technique and assembly of the miniaturized pen-size instrument are described. The optical system was adjusted to fit into a handy device which could potentially access different positions in the oral cavity. The assembled instrument could successfully detect early erosion progression in both polished (n=70) and native (n=20) human enamels. Different severities of enamel erosion were induced by varying incubation time of polished enamel in 1% citric acid (pH=3.60, 0.5 to 10 min), while the native incisors were treated in the commercial orange juice (Tropicana Pure Premium®, pH=3.85, 10 to 60 min). The instrument provided a good differentiation between various severities of the erosion in vitro. The size of the measurement spot affected the erosion monitoring in native enamel (human incisors). The erosion measurement in the 0.7-mm (diameter) cervical spots showed systematically lower reflection intensities compared with the analysis of central and incisal small spots. The application of larger spot areas (2.3 mm) for the erosion monitoring revealed no effect (p>0.05) of the spot position on the reflection signal. High variation of the teeth susceptibility toward in vitro erosion was detected in native enamel. PMID:24247749

  6. In-office dental bleaching and enamel microabrasion for fluorosis treatment.

    PubMed

    Bertassoni, Luiz E; Martin, Juliana M H; Torno, Vladja; Vieira, Sérgio; Rached, Rodrigo Nunes; Mazur, Rui F

    2008-01-01

    Recently, mostly as a result of drinking water fluoridation, the number of young patients affected by fluorosis increased considerably. This study describes a minimally invasive technique, using in-office dental bleaching (35% hydrogen peroxide) and enamel microabrasion (silicon carbide and 12% hydrochloric acid) to eliminate fluorosis like stains. The association of techniques was efficient and can be recommended as a good conservative alternative for the treatment of fluorosis affected teeth. PMID:18524266

  7. OSL and thermally assisted OSL response in dental enamel for its possible application in retrospective dosimetry.

    PubMed

    Soni, Anuj; Mishra, D R; Polymeris, G S; Bhatt, B C; Kulkarni, M S

    2014-11-01

    Dental enamel was studied for its thermoluminescence (TL) and optically stimulated luminescence (OSL) defects. The TL studies showed a wide glow curve with multiple peaks. The thermally assisted OSL (TA-OSL) studies showed that the integrated TA-OSL and thus OSL signal increases with readout temperature between 100 and 250 °C, due to the temperature dependence of OSL. The thermally assisted energy E A associated with this increase is found to be 0.21 ± 0.015 eV. On the other hand, the signal intensity decreases with temperature between 260 and 450 °C. This decrease could be due to depletion of OSL active traps or possible thermal quenching. The increase of the OSL signal at increased temperature can be used to enhance the sensitivity of dental enamel for ex vivo measurements in retrospective dosimetry. The emission and excitation spectra of its luminescence centers were studied by photoluminescence and were found to be at 412 and 324 nm, respectively. It was found to possess multiple OSL active traps having closely lying photoionization cross sections characterized by continuous wave OSL and nonlinear OSL methods. The investigated dental enamel samples showed a linear OSL dose response up to 500 Gy. The dose threshold was found to be 100 mGy using a highly sensitive compact OSL reader with blue LED (470 nm) stimulation. PMID:24929347

  8. Inhibition of enamel demineralization by buffering effect of S-PRG filler-containing dental sealant.

    PubMed

    Kaga, Masayuki; Kakuda, Shinichi; Ida, Yusuke; Toshima, Hirokazu; Hashimoto, Masanori; Endo, Kazuhiko; Sano, Hidehiko

    2014-02-01

    The buffering capacity and inhibitory effects on enamel demineralization of two commercially available dental sealants were evaluated in this study. The effects of filler particles were also examined. Disks of enamel and cured sealant materials of BeautiSealant (silica or S-PRG filler) or Teethmate F-1 were incubated in lactic acid solutions (pH 4.0) for 1-6 d. The pH changes and amounts of ions released in the solutions were assessed, and enamel surfaces were observed using a scanning electron microscope. The pH of the solution with BeautiSealant (S-PRG filler) was neutralized from pH 4.0 to pH 6.1 (after incubation for 1 d) and from pH 4.0 to pH 6.7 (after incubation for 6 d). In addition, no release of calcium ions was detected and the enamel surface was morphologically intact in scanning electron microscopy images. However, the pH of the solution with Teethmate F-1 remained below pH 4.0 during incubation from days 1 to 6. Calcium release was increased in solutions up to and after 6 d of incubation. Scanning electron microscopy images showed that the structures of hydroxyapatite rods were exposed at the specimen surfaces as a result of demineralization. Ions released from S-PRG filler-containing dental sealant rapidly buffered the lactic acid solution and inhibited enamel demineralization. PMID:24372898

  9. Dental Enamel Irradiated with Infrared Diode Laser and Photoabsorbing Cream: Part 1—FT-Raman Study

    PubMed Central

    Dos Santos, Edson Aparecido Pereira; Soares, Luís Eduardo Silva; Do Espírito Santo, Ana Maria; Martin, Airton Abrahão; Duarte, Danilo Antônio; Pacheco-Soares, Cristina; Brugnera, Aldo

    2009-01-01

    Abstract Objective: The aim of this FT-Raman study was to investigate laser-induced compositional changes in enamel after therapy with a low-level infrared diode laser and a photoabsorbing cream, in order to intensify the superficial light absorption before and after cariogenic challenge. Background Data: Dental caries remains the most prevalent disease during childhood and adolescence. Preventive modalities include the use of fluoride, reduction of dietary cariogenic refined carbohydrates, plaque removal and oral hygiene techniques, and antimicrobial prescriptions. A relatively simple and noninvasive caries preventive regimen is treating tooth enamel with laser irradiation, either alone or in combination with topical fluoride treatment, resulting in reduced enamel solubility and dissolution rates. Due to their high cost, high-powered lasers are still not widely employed in private practice in developing countries. Thus, low-power red and near-infrared lasers appear to be an appealing alternative. Materials and Methods: Twenty-four extracted or exfoliated caries-free deciduous molars were divided into six groups: control group (no treatment; n = 8); infrared laser treatment (L; n = 8) (810 nm at 100 mW/cm2 for 90 sec); infrared diode laser irradiation (810 nm at 100 mW/cm2 for 90 sec) and photoabsorbing cream (IVL; n = 8); photoabsorbing cream alone (IV; n = 8); infrared diode laser irradiation (810 nm at 100 mW/cm2 for 90 sec) and fluorinated photoabsorbing agent (IVLF; n = 8); and fluorinated photoabsorbing agent alone (IVF; n = 8). Samples were analyzed using FT-Raman spectroscopy before and after pH cycling cariogenic challenge. Results: There was a significant laser-induced reduction and possible modification of the organic matrix content in enamel treated with the low-level diode laser (the L, IVL, and IVFL groups). Conclusion: The FT-Raman technique may be suitable for detecting compositional and structural changes

  10. Effect of amine fluoride/stannous fluoride-containing toothpaste and mouthrinsings on dental plaque, gingivitis, plaque and enamel F-accumulation.

    PubMed

    Bánóczy, J; Szöke, J; Kertész, P; Töth, Z; Zimmermann, P; Gintner, Z

    1989-01-01

    The aim of the study was to assess the effect of an amine fluoride/stannous fluoride toothpaste and mouthwash on dental plaque and gingivitis, plaque F- accumulation, F- content and acid solubility of dental enamel. Participants in the 12-week double-blind study were 92 schoolchildren, with a mean age of 12.4 years, randomly distributed to four groups: (1) AmF/SnF2 toothpaste, (2) placebo toothpaste, (3) AmF/SnF2 toothpaste plus AmF/SnF2 mouthwash, (4) placebo toothpaste plus AmF/SnF2 mouthwash. Analyzing the results, the mean values of dental plaque (Silness-Löe index) and of the sulcus bleeding index decreased statistically significantly in all groups except the placebo toothpaste users. Plaque F- and enamel F- content increased considerably only in the two groups using the AmF/SnF2 toothpaste. A decrease in acid solubility was significant only in the group of both test toothpaste and test mouthwash users. Thus the clinical efficacy of the tested AmF/SnF2 toothpaste might be increased by the combined use of mouthrinsings containing the same substances. PMID:2790865

  11. A Coaxial Dielectric Probe Technique for Distinguishing Tooth Enamel from Dental Resin

    PubMed Central

    Williams, Benjamin B.; Geimer, Shireen D.; Flood, Ann B.; Swartz, Harold M.

    2016-01-01

    For purposes of biodosimetry in the event of a large scale radiation disaster, one major and very promising point-of contact device is assessing dose using tooth enamel. This technique utilizes the capabilities of electron paramagnetic resonance to measure free radicals and other unpaired electron species, and the fact that the deposition of energy from ionizing radiation produces free radicals in most materials. An important stipulation for this strategy is that the measurements, need to be performed on a central incisor that is basically intact, i.e. which has an area of enamel surface that is as large as the probing tip of the resonator that is without decay or restorative care that replaces the enamel. Therefore, an important consideration is how to quickly assess whether the tooth has sufficient enamel to be measured for dose and whether there is resin present on the tooth being measured and to be able to characterize the amount of surface that is impacted. While there is a relatively small commercially available dielectric probe which could be used in this context, it has several disadvantages for the intended use. Therefore, a smaller, 1.19mm diameter 50 ohm, open-ended, coaxial dielectric probe has been developed as an alternative. The performance of the custom probe was validated against measurement results of known standards. Measurements were taken of multiple teeth enamel and dental resin samples using both probes. While the probe contact with the teeth samples was imperfect and added to measurement variability, the inherent dielectric contrast between the enamel and resin was sufficient that the probe measurements could be used as a robust means of distinguishing the two material types. The smaller diameter probe produced markedly more definitive results in terms of distinguishing the two materials. PMID:27182531

  12. Effects of enamel matrix genes on dental caries are moderated by fluoride exposures

    PubMed Central

    Shaffer, John R.; Carlson, Jenna C.; Stanley, Brooklyn O. C.; Feingold, Eleanor; Cooper, Margaret; Vanyukov, Michael M.; Maher, Brion S.; Slayton, Rebecca L.; Willing, Marcia C.; Reis, Steven E.; McNeil, Daniel W.; Crout, Richard J.; Weyant, Robert J.; Levy, Steven M.; Vieira, Alexandre R.; Marazita, Mary L.

    2014-01-01

    Dental caries (tooth decay) is the most common chronic disease, worldwide, affecting most children and adults. Though dental caries is highly heritable, few caries-related genes have been discovered. We investigated whether 18 genetic variants in the group of nonamelogenin enamel matrix genes (AMBN, ENAM, TUFT1, and TFIP11) were associated with dental caries experience in 13 age- and race-stratified samples from six parent studies (N=3,600). Linear regression was used to model genetic associations and test gene-byfluoride interaction effects for two sources of fluoride: daily tooth brushing and home water fluoride concentration. Meta-analysis was used to combine results across five child and eight adult samples. We observed the statistically significant association of rs2337359 upstream of TUFT1 with dental caries experience via meta-analysis across adult samples (p<0.002) and the suggestive association for multiple variants in TFIP11 across child samples (p<0.05). Moreover, we discovered two genetic variants (rs2337359 upstream of TUFT1 and missense rs7439186 in AMBN) involved in gene-by-fluoride interactions. For each interaction, participants with the risk allele/genotype exhibited greater dental caries experience only if they were not exposed to the source of fluoride. Altogether, these results confirm that variation in enamel matrix genes contributes to individual differences in dental caries liability, and demonstrate that the effects of these genes may be moderated by protective fluoride exposures. In short, genes may exert greater influence on dental caries in unprotected environments, or equivalently, the protective effects of fluoride may obviate the effects of genetic risk alleles. PMID:25373699

  13. Effects of enamel matrix genes on dental caries are moderated by fluoride exposures.

    PubMed

    Shaffer, John R; Carlson, Jenna C; Stanley, Brooklyn O C; Feingold, Eleanor; Cooper, Margaret; Vanyukov, Michael M; Maher, Brion S; Slayton, Rebecca L; Willing, Marcia C; Reis, Steven E; McNeil, Daniel W; Crout, Richard J; Weyant, Robert J; Levy, Steven M; Vieira, Alexandre R; Marazita, Mary L

    2015-02-01

    Dental caries (tooth decay) is the most common chronic disease, worldwide, affecting most children and adults. Though dental caries is highly heritable, few caries-related genes have been discovered. We investigated whether 18 genetic variants in the group of non-amelogenin enamel matrix genes (AMBN, ENAM, TUFT1, and TFIP11) were associated with dental caries experience in 13 age- and race-stratified samples from six parent studies (N = 3,600). Linear regression was used to model genetic associations and test gene-by-fluoride interaction effects for two sources of fluoride: daily tooth brushing and home water fluoride concentration. Meta-analysis was used to combine results across five child and eight adult samples. We observed the statistically significant association of rs2337359 upstream of TUFT1 with dental caries experience via meta-analysis across adult samples (p < 0.002) and the suggestive association for multiple variants in TFIP11 across child samples (p < 0.05). Moreover, we discovered two genetic variants (rs2337359 upstream of TUFT1 and missense rs7439186 in AMBN) involved in gene-by-fluoride interactions. For each interaction, participants with the risk allele/genotype exhibited greater dental caries experience only if they were not exposed to the source of fluoride. Altogether, these results confirm that variation in enamel matrix genes contributes to individual differences in dental caries liability, and demonstrate that the effects of these genes may be moderated by protective fluoride exposures. In short, genes may exert greater influence on dental caries in unprotected environments, or equivalently, the protective effects of fluoride may obviate the effects of genetic risk alleles. PMID:25373699

  14. Dental radiography: tooth enamel EPR dose assessment from Rando phantom measurements

    NASA Astrophysics Data System (ADS)

    Aragno, D.; Fattibene, P.; Onori, S.; Aragno, D.; Fattibene, P.

    2000-09-01

    Electron paramagnetic resonance dosimetry of tooth enamel is now established as a suitable method for individual dose reconstruction following radiation accidents. The accuracy of the method is limited by some confounding factors, among which is the dose received due to medical x-ray irradiation. In the present paper the EPR response of tooth enamel to endoral examination was experimentally evaluated using an anthropomorphic phantom. The dose to enamel for a single exposure of a typical dental examination performed with a new x-ray generation unit working at 65 kVp gave rise to a CO2- signal of intensity similar to that induced by a dose of about 2 mGy of 60Co. EPR measurements were performed on the entire tooth with no attempt to separate buccal and lingual components. Also the dose to enamel for an orthopantomography exam was estimated. It was derived from TLD measurements as equivalent to 0.2 mGy of 60Co. In view of application to risk assessment analysis, in the present work the value for the ratio of the reference dose at the phantom surface measured with TLD to the dose at the tooth measured with EPR was determined.

  15. Evaluation of X-ray microanalysis for characterization of dental enamel.

    PubMed

    Melin, Lisa; Norén, Jörgen G; Taube, Fabian; Cornell, David H

    2014-02-01

    Elemental analysis of dental hard tissues is of importance. The aim of this study is to evaluate X-ray microanalysis (XRMA) of bovine enamel in a scanning electron microscope (SEM) with different coatings. The buccal surface of bovine incisors was polished flat, one-third was coated with carbon, one-third with gold, leaving one-third uncoated for XRMA in an SEM equipped with an energy-dispersive microanalysis system. The elements oxygen, sodium, magnesium, phosphorous, chlorine, potassium, and calcium were analyzed using their respective characteristic K X-ray series. Comparisons were made with analyses of glass produced by fusion of the bovine enamel, showing that oxygen analyses using the K X-ray series are reliable and preferable to calculating oxygen by stoichiometry for natural enamel. For the gold-coated and uncoated analyses, carbon was also measured using the K X-ray series. Small area Analyses in small areas (80 × 80 μm) in variable pressure-SEM mode with low vacuum (20 Pa), without any coating, midway between 40 μm wide gold lines 140 μm apart to avoid build-up of electrostatic charge is the preferred method, especially if carbon is included in the analysis. The analyses of bovine enamel are sufficiently reproducible to be regarded as quantitative for all elements except carbon. PMID:24461037

  16. Nature of light scattering in dental enamel and dentin at visible and near-infrared wavelengths

    NASA Astrophysics Data System (ADS)

    Fried, Daniel; Glena, Richard E.; Featherstone, John D. B.; Seka, Wolf

    1995-03-01

    The light-scattering properties of dental enamel and dentin were measured at 543, 632, and 1053 nm. Angularly resolved scattering distributions for these materials were measured from 0 deg to 180 deg using a rotating goniometer. Surface scattering was minimized by immersing the samples in an index-matching bath. The scattering and absorption coefficients and the scattering phase function were deduced by comparing the measured scattering data with angularly resolved Monte Carlo light-scattering simulations. Enamel and dentin were best represented by a linear combination of a highly forward-peaked Henyey-Greenstein (HG) phase function and an isotropic phase function. Enamel weakly scatters light between 543 nm and 1.06 mu m, with the scattering coefficient ( mu s) ranging from mu s = 15 to 105 cm-1. The phase function is a combination of a HG function with g = 0.96 and a 30-60% isotropic phase function. For enamel, absorption is negligible. Dentin scatters strongly in the visible and near IR ( mu s approximately equals 260 cm-1) and absorbs weakly ( mu a approximately equals 4 cm-1). The scattering phase function for dentin is described by a HG function with g = 0.93 and a very weak isotropic scattering component ( approximately 2%).

  17. Enamel crystals of mice susceptible or resistant to dental fluorosis: an AFM study

    PubMed Central

    BUZALAF, Marília Afonso Rabelo; BARBOSA, Carolina Silveira; LEITE, Aline de Lima; CHANG, Sywe-Ren; LIU, Jun; CZAJKA-JAKUBOWSKA, Agata; CLARKSON, Brian

    2014-01-01

    Objective This study aimed to assess the overall apatite crystals profile in the enamel matrix of mice susceptible (A/J strain) or resistant (129P3/J strain) to dental fluorosis through analyses by atomic force microscopy (AFM). Material and Methods Samples from the enamel matrix in the early stages of secretion and maturation were obtained from the incisors of mice from both strains. All detectable traces of matrix protein were removed from the samples by a sequential extraction procedure. The purified crystals (n=13 per strain) were analyzed qualitatively in the AFM. Surface roughness profile (Ra) was measured. Results The mean (±SD) Ra of the crystals of A/J strain (0.58±0.15 nm) was lower than the one found for the 129P3/J strain (0.66±0.21 nm) but the difference did not reach statistical significance (t=1.187, p=0.247). Crystals of the 129P3/J strain (70.42±6.79 nm) were found to be significantly narrower (t=4.013, p=0.0013) than the same parameter measured for the A/J strain (90.42±15.86 nm). Conclusion Enamel crystals of the 129P3/J strain are narrower, which is indicative of slower crystal growth and could interfere in the occurrence of dental fluorosis. PMID:25025555

  18. Surface nanomorphology of human dental enamel irradiated with an Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Ţălu, Ş.; Contreras–Bulnes, R.; Morozov, I. A.; Rodríguez-Vilchis, L. E.; Montoya-Ayala, G.

    2016-02-01

    To determine the effects of Er:YAG laser irradiation on the surface nanomorphology of human dental enamel. Materials and methods: five samples of human dental enamel were divided into five groups: (a) I and II were irradiated with Er:YAG & water irrigation (12.7 J cm-2 and 25.5 J cm-2, respectively); (b) III and IV were Er:YAG laser irradiated & no water irrigation (12.7 J cm-2 and 25.5 J cm-2, respectively); (c) V or control (no laser irradiation). Nanomorphological changes were observed on 1 μm  ×  1 μm areas by AFM (contact mode and air). The partition functions and multifractal spectra were calculated. The graphical results showed that the larger the spectrum width Δα (Δα  =  α max  -  α min) of the multifractal spectra f(α) the more non-uniform the surface nanomorphology. One way analysis of variance (ANOVA) was performed (P  <  0.05) to distinguish significant differences between the groups. All the investigated surfaces exhibited multifractal behavior. The computational algorithm indicated that the multifractal spectra differ significantly from each other for the different groups. AFM (atomic force microscopy), the statistical surface roughness parameters, and multifractal analysis provided useful information about the surface nanomorphology and optimal surface characteristics. This approach could be extended to other enamel surfaces in order to characterize its structural 3D microrelief.

  19. Alteration of Dentin-Enamel Mechanical Properties Due to Dental Whitening Treatments

    PubMed Central

    Zimmerman, B.; Datko, L.; Cupelli, M.; Alapati, S.; Dean, D.; Kennedy, M.

    2010-01-01

    The mechanical properties of dentin and enamel affect the reliability and wear properties of a tooth. This study investigated the influence of clinical dental treatments and procedures, such as whitening treatments or etching prior to restorative procedures. Both autoclaved and non-autoclaved teeth were studied in order to allow for both comparison with published values and improved clinical relevance. Nanoindentation analysis with the Oliver-Pharr model provided elastic modulus and hardness across the dentin-enamel junction (DEJ). Large increases were observed in the elastic modulus of enamel in teeth that had been autoclaved (52.0GPa versus 113.4GPa), while smaller increases were observed in the dentin (17.9GPa versus 27.9GPa). Likewise, there was an increase in the hardness of enamel (2.0GPa versus 4.3GPa) and dentin (0.5GPa versus 0.7GPa) with autoclaving. These changes suggested that the range of elastic modulus and hardness values previously reported in literature may be partially due to the sterilization procedures. Treatment of the exterior of non-autoclaved teeth with Crest Whitestrips™, Opalescence™ or UltraEtch™ caused changes in the mechanical properties of both the enamel and dentin. Those treated with Crest Whitestrips™ showed a reduction in the elastic modulus of enamel (55.3GPa to 32.7GPa) and increase in the elastic modulus of dentin (17.2GPa to 24.3GPa). Opalescence™ treatments did not significantly affect the enamel properties, but did result in a decrease in modulus of dentin (18.5GPa to 15.1GPa). Additionally, as expected, UltraEtch™ treatment decreased the modulus and hardness of enamel (48.7GPa to 38.0GPa and 1.9GPa to 1.5GPa, respectively) and dentin (21.4GPa to 15.0GPa and 1.9GPa to 1.5GPa, respectively). Changes in the mechanical properties were linked to altered protein concentration within the tooth, as evidenced by fluorescence microscopy and Fourier transform infrared spectroscopy. PMID:20346902

  20. Evaluation of dental enamel caries assessment using Quantitative Light Induced Fluorescence and Optical Coherence Tomography.

    PubMed

    Maia, Ana Marly Araújo; de Freitas, Anderson Zanardi; de L Campello, Sergio; Gomes, Anderson Stevens Leônidas; Karlsson, Lena

    2016-06-01

    An in vitro study of morphological alterations between sound dental structure and artificially induced white spot lesions in human teeth, was performed through the loss of fluorescence by Quantitative Light-Induced Fluorescence (QLF) and the alterations of the light attenuation coefficient by Optical Coherence Tomography (OCT). To analyze the OCT images using a commercially available system, a special algorithm was applied, whereas the QLF images were analyzed using the software available in the commercial system employed. When analyzing the sound region against white spot lesions region by QLF, a reduction in the fluorescence intensity was observed, whilst an increase of light attenuation by the OCT system occurred. Comparison of the percentage of alteration between optical properties of sound and artificial enamel caries regions showed that OCT processed images through the attenuation of light enhanced the tooth optical alterations more than fluorescence detected by QLF System. QLF versus OCT imaging of enamel caries: a photonics assessment. PMID:26351155

  1. An in vitro study of the microstructure, composition and nanoindentation mechanical properties of remineralizing human dental enamel

    NASA Astrophysics Data System (ADS)

    Arsecularatne, J. A.; Hoffman, M.

    2014-08-01

    This paper describes the results of an in vitro investigation on the interrelations among microstructure, composition and mechanical properties of remineralizing human dental enamel. Polished enamel samples have been demineralized for 10 min in an acetic acid solution (at pH 3) followed by remineralization in human saliva for 30 and 120 min. Microstructure variations of sound, demineralized and remineralized enamel samples have been analysed using focused ion beam, scanning electron microscopy and transmission electron microscopy, while their compositions have been analysed using energy dispersive x-ray. Variations in the mechanical properties of enamel samples have been assessed using nanoindentation. The results reveal that, under the selected conditions, only partial remineralization of the softened enamel surface layer occurs where some pores remain unrepaired. As a result, while the nanoindentation elastic modulus shows an improvement following remineralization, hardness does not.

  2. The effect on the ultrastructure of dental enamel of excimer-dye, argon-ion and CO2 lasers.

    PubMed

    Palamara, J; Phakey, P P; Orams, H J; Rachinger, W A

    1992-12-01

    This study aimed to investigate the ultrastructural changes that occur in dental enamel irradiated with pulsed excimer-dye, continuous-wave (CW) argon-ion and CW CO2 lasers. The pulsed excimer-dye laser produced deep craters, rough damaged surfaces with underlying porosity and amorphous vitrified material. The vitrification of the enamel indicated that the temperature in these areas must have been at least in the range 1280 to 1600 degrees C. The CW argon-ion laser irradiation produced a changed non-cratered surface with inter-crystalline porosity and a mixture of small and some large irregularly packed recrystallized enamel crystals. The CW CO2 laser produced shallow craters, surface crazing and lifting off the removal of the surface layer to expose the underlying roughened enamel. The ultrastructure revealed inter- and intra-crystalline porosity, a mixture of small but variable size irregularly packed recrystallized enamel crystals and also well packed large crystals which indicated further grain growth. The porosity in lased enamel was overall very similar to that seen in enamel heated in an electric furnace to a temperature of 600 degrees C. The presence of recrystallized enamel crystals indicated a temperature rise of approximately 1000 degrees C and the grain growth indicated that a temperature > or = 1000 degrees C existed for some time after the laser irradiation. In general the excimer-dye laser produced most surface destruction because of its higher power density and shorter interaction time and the argon-ion laser produced least damage. These results indicated that the lasers used in this study require much more refinement before they can find therapeutic application to dental enamel, and this may well be the case for other lasers being investigated for clinical dental practise. PMID:1295076

  3. Do pediatric medicines induce topographic changes in dental enamel?

    PubMed

    Alexandria, Adílis Kalina; Meckelburg, Nicolli de Araujo; Puetter, Ursula Tavares; Salles, Jordan Trugilho; Souza, Ivete Pomarico Ribeiro; Maia, Lucianne Cople

    2016-01-01

    The purpose of the present study was to evaluate the effect of common pediatric liquid medicines on surface roughness and tooth structure loss and to evaluate the pH values of these medicines at room and cold temperatures in vitro. Eighty-four bovine enamel blocks were divided into seven groups (n = 12): G1-Alivium®, G2-Novalgina®, G3-Betamox®, G4-Clavulin®, G5-Claritin®, G6-Polaramine® and G7-Milli-Q water (negative control). The pH was determined and the samples were immersed in each treatment 3x/day for 5 min. 3D non-contact profilometry was used to determine surface roughness (linear Ra, volumetric Sa) and the Gap formed between treated and control areas in each block. Scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) were also performed. The majority of liquid medicines had pH ≤ 5.50. G1, G4, and G5 showed alterations in Ra when compared with G7 (p < 0.05). According to Sa and Gap results, only G5 was different from G7 (p < 0.05). Alteration in surface was more evident in G5 SEM images. EDS revealed high concentrations of carbon, oxygen, phosphorus, and calcium in all tested groups. Despite the low pH values of all evaluated medicines, only Alivium®, Clavulin®, and Claritin® increased linear surface roughness, and only Claritin® demonstrated the in vitro capacity to produce significant tooth structure loss. PMID:26676189

  4. Combinatorial localized dissolution analysis: Application to acid-induced dissolution of dental enamel and the effect of surface treatments.

    PubMed

    Parker, Alexander S; Al Botros, Rehab; Kinnear, Sophie L; Snowden, Michael E; McKelvey, Kim; Ashcroft, Alexander T; Carvell, Mel; Joiner, Andrew; Peruffo, Massimo; Philpotts, Carol; Unwin, Patrick R

    2016-08-15

    A combination of scanning electrochemical cell microscopy (SECCM) and atomic force microscopy (AFM) is used to quantitatively study the acid-induced dissolution of dental enamel. A micron-scale liquid meniscus formed at the end of a dual barrelled pipette, which constitutes the SECCM probe, is brought into contact with the enamel surface for a defined period. Dissolution occurs at the interface of the meniscus and the enamel surface, under conditions of well-defined mass transport, creating etch pits that are then analysed via AFM. This technique is applied to bovine dental enamel, and the effect of various treatments of the enamel surface on acid dissolution (1mM HNO3) is studied. The treatments investigated are zinc ions, fluoride ions and the two combined. A finite element method (FEM) simulation of SECCM mass transport and interfacial reactivity, allows the intrinsic rate constant for acid-induced dissolution to be quantitatively determined. The dissolution of enamel, in terms of Ca(2+) flux ( [Formula: see text] ), is first order with respect to the interfacial proton concentration and given by the following rate law: [Formula: see text] , with k0=0.099±0.008cms(-1). Treating the enamel with either fluoride or zinc ions slows the dissolution rate, although in this model system the partly protective barrier only extends around 10-20nm into the enamel surface, so that after a period of a few seconds dissolution of modified surfaces tends towards that of native enamel. A combination of both treatments exhibits the greatest protection to the enamel surface, but the effect is again transient. PMID:27209395

  5. Prevalence and Association of Developmental Defects of Enamel with, Dental- Caries and Nutritional Status in Pre-School Children, Lucknow

    PubMed Central

    Saha, Sabyasachi; Jagannath, G.V.; Singh, Sanjay

    2015-01-01

    Background Developmental Defects of Enamel in the primary dentition may be associated and predictors of dental caries and nutritional status. The aim of the present study was to assess the Prevalence of Developmental Defects of Enamel and its Association with, Dental-Caries and Nutritional Status in Pre-School Children of Lucknow, India. Materials and Methods Multistage Sampling was done. A total of 302 pre-school (Rural and Urban) children were examined. Type III examination was conducted with WHO Probe. Developmental Enamel Defects (DED) and Dental Caries were assessed using WHO (1997) Proforma. Results The prevalence of DED of any type was 39.9% with that of demarcated opacities being the highest, followed by hypoplasia. The most frequently affected teeth were maxillary anterior teeth, while the least affected teeth were mandibular incisors. The mean dmft was 3.5. A positive association between DED and caries was observed. Association between Dental Caries & BMI was non-significant whereas Pearson correlation showed a negative correlation between the two. Conclusion The prevalence of enamel defects and caries was high, as the enamel defects were strongly associated with caries. PMID:26557622

  6. [In vitro experiments on effect of soft drinks on dental enamel].

    PubMed

    Grenby, T H

    1990-09-01

    The composition and dental properties of eight different soft drinks, representing some of the most popular types used in the U.K., were examined. Demineralisation experiments were conducted on hydroxylapatite, the basic component of dental enamel, determining calcium dissolving by atomic absorption spectroscopy and phosphorus by UV/vis spectrophotometry. The titratable acid content of the drinks was found to give a better guide than their pH to their potential dental erosiveness. The sugars content, in their ready-to-drink form, varied from zero in a low-calorie product up to almost 14% in a black-currant drink, but using a technique with a relatively long contact time, and in the absence of intact dental plaque, the demineralising action on hydroxylapatite of the acids already in the drinks eclipsed the effects of the acid generated by oral micro-organisms from the sugars in the drinks. The pure citrus juices showed potentially the worst dental properties, followed by the orange and blackcurrant concentrates after dilution to their ready-to-drink form, with least demineralisation from the carbonated drinks, and a cola drink giving especially low figures. PMID:1966262

  7. Damage modeling of small-scale experiments on dental enamel with hierarchical microstructure.

    PubMed

    Scheider, I; Xiao, T; Yilmaz, E; Schneider, G A; Huber, N; Bargmann, S

    2015-03-01

    Dental enamel is a highly anisotropic and heterogeneous material, which exhibits an optimal reliability with respect to the various loads occurring over years. In this work, enamel's microstructure of parallel aligned rods of mineral fibers is modeled and mechanical properties are evaluated in terms of strength and toughness with the help of a multiscale modeling method. The established model is validated by comparing it with the stress-strain curves identified by microcantilever beam experiments extracted from these rods. Moreover, in order to gain further insight in the damage-tolerant behavior of enamel, the size of crystallites below which the structure becomes insensitive to flaws is studied by a microstructural finite element model. The assumption regarding the fiber strength is verified by a numerical study leading to accordance of fiber size and flaw tolerance size, and the debonding strength is estimated by optimizing the failure behavior of the microstructure on the hierarchical level above the individual fibers. Based on these well-grounded properties, the material behavior is predicted well by homogenization of a representative unit cell including damage, taking imperfections (like microcracks in the present case) into account. PMID:25484332

  8. Genes Expressed in Dental Enamel Development Are Associated with Molar-Incisor Hypomineralization

    PubMed Central

    Jeremias, Fabiano; Koruyucu, Mine; Küchler, Erika C.; Bayram, Merve; Tuna, Elif B.; Deeley, Kathleen; Pierri, Ricardo A.; Souza, Juliana F.; Fragelli, Camila M.B.; Paschoal, Marco A.B.; Gencay, Koray; Seymen, Figen; Caminaga, Raquel M.S.; dos Santos-Pinto, Lourdes; Vieira, Alexandre R.

    2013-01-01

    Genetic disturbances during dental development influence variation of number and shape of the dentition. In this study, we tested if genetic variation in enamel formation genes is associated with molar-incisor hypomineralization (MIH), also taking into consideration caries experience. DNA samples from 163 cases with MIH and 82 unaffected controls from Turkey, and 71 cases with MIH and 89 unaffected controls from Brazil were studied. Eleven markers in five genes [ameloblastin (AMBN), amelogenin (AMELX), enamelin (ENAM), tuftelin (TUFT1), and tuftelin-interacting protein 11 (TFIP11)] were genotyped by the TaqMan method. Chi-square was used to compare allele and genotype frequencies between cases with MIH and controls. In the Brazilian data, distinct caries experience within the MIH group was also tested for association with genetic variation in enamel formation genes. The ENAM rs3796704 marker was associated with MIH in both populations (Brazil: p=0.03; OR=0.28; 95% C.I.=0.06–1.0; Turkey: p=1.22e–012; OR=17.36; 95% C.I.=5.98–56.78). Associations between TFIP11 (p=0.02), ENAM (p=0.00001), and AMELX (p=0.01) could be seen with caries independent of having MIH or genomic DNA copies of Streptococcus mutans detected by real time PCR in the Brazilian sample. Several genes involved in enamel formation appear to contribute to MIH. PMID:23790503

  9. Surface dental enamel lead levels and antisocial behavior in Brazilian adolescents.

    PubMed

    Olympio, Kelly P K; Oliveira, Pedro V; Naozuka, Juliana; Cardoso, Maria R A; Marques, Antonio F; Günther, Wanda M R; Bechara, Etelvino J H

    2010-01-01

    Lead poisoning has been reportedly linked to a high risk of learning disabilities, aggression and criminal offenses. To study the association between lead exposure and antisocial/delinquent behavior, a cross-sectional study was conducted with 173 Brazilian youths aged 14-18 and their parents (n=93), living in impoverished neighborhoods of Bauru-SP, with high criminality indices. Self-Reported Delinquency (SRD) and Child Behavior Checklist (CBCL) questionnaires were used to evaluate delinquent/antisocial behavior. Body lead burdens were evaluated in surface dental enamel acid microbiopsies. The dental enamel lead levels (DELL) were quantified by graphite furnace atomic absorption spectrometry (GFAAS) and phosphorus content was measured using inductively coupled plasma optical emission spectrometry (ICP-OES). Logistic regression was used to identify associations between DELL and each scale defined by CBCL and SRD scores. Odd ratios adjusted for familial and social covariates, considering a group of youths exposed to high lead levels (>or=75 percentile), indicated that high DELL is associated with increased risk of exceeding the clinical score for somatic complaints, social problems, rule-breaking behavior and externalizing problems (CI 95%). High DELL was not found to be associated with elevated SRD scores. In conclusion, our data support the hypothesis that high-level lead exposure can trigger antisocial behavior, which calls for public policies to prevent lead poisoning. PMID:20005947

  10. Influence of buffered and unbuffered acetylsalicylic acid on dental enamel and dentine in human teeth: an in vitro pilot study.

    PubMed

    Rogalla, K; Finger, W; Hannig, M

    1992-06-01

    An in vitro study was conducted to investigate the erosive effect of buffered and unbuffered acetylsalicylic acid (ASA) on dental enamel and dentine in human teeth by scanning electron microscopy. In order to standardize the specimens and to improve comparability the dental enamel and dentine were superficially abraded. The enamel and dentine specimens were therefore particularly sensitive to the influences of acid agents. Concentrated solution of buffered chewable ASA tablets (500 mg ASA and 300 mg calcium carbonate in 5 ml water) showed no changes in the enamel surface structure after exposure times of 1 min, 5 min and 60 min. In contrast, minimal corrosive effects were already seen after exposure of the enamel surface to the unbuffered ASA solutions for 1 min. After exposure times of 5 min and 60 min erosion of the enamel was more pronounced. Immersion in the unbuffered ASA solution led to clearly visible micromorphological changes on the dentine surfaces even after exposure for 1 min. Exposure of the dentine specimens to the buffered ASA solutions led to only very slight changes in the surface morphology. Therefore, the scanning electron micrograph after exposure to buffered ASA is comparable to the picture of untreated dentine. PMID:1513188

  11. The role of mesoscopic modelling in understanding the response of dental enamel to mid-infrared radiation

    NASA Astrophysics Data System (ADS)

    Vila Verde, A.; Ramos, M. M. D.; Stoneham, A. M.

    2007-05-01

    Human dental enamel has a porous mesostructure at the nanometre to micrometre scales that affects its thermal and mechanical properties relevant to laser treatment. We exploit finite-element models to investigate the response of this mesostructured enamel to mid-infrared lasers (CO2 at 10.6 µm and Er:YAG at 2.94 µm). Our models might easily be adapted to investigate ablation of other brittle composite materials. The studies clarify the role of pore water in ablation, and lead to an understanding of the different responses of enamel to CO2 and Er:YAG lasers, even though enamel has very similar average properties at the two wavelengths. We are able to suggest effective operating parameters for dental laser ablation, which should aid the introduction of minimally-invasive laser dentistry. In particular, our results indicate that, if pulses of ap10 µs are used, the CO2 laser can ablate dental enamel without melting, and with minimal damage to the pulp of the tooth. Our results also suggest that pulses with 0.1-1 µs duration can induce high stress transients which may cause unwanted cracking.

  12. Polarization resolved near-IR imaging of sound and carious dental enamel

    NASA Astrophysics Data System (ADS)

    Darling, Cynthia L.; Chan, Kenneth H.; Fried, Daniel

    2011-03-01

    A thorough understanding of how polarized near-IR light is reflected from and transmitted through sound and carious dental hard tissues is important for the development of optical imaging devices. New optical imaging tools employing non-ionizing radiation are needed for the detection and assessment of dental caries. In this investigation, an automated system was developed to collect images for the full 16-element Mueller Matrix. The polarized light was controlled by linear polarizers and liquid crystal retarders and the 36 images were acquired as the polarized near-IR light is reflected from the occlusal surface or transmitted through thin sections of extracted human whole teeth. Previous near-IR imaging studies suggest that polarization imaging can be exploited to obtain higher contrast images of early dental caries due to the rapid depolarization of incident polarized light by the highly scattering areas of decay. In this study, the reflectance from tooth occlusal surfaces with demineralization and transmitted light through tooth thin sections with caries lesions were investigated. Major differences in the Mueller matrix elements were observed in both sound and demineralized enamel. This study suggests that polarization resolved optical imaging can be exploited to obtain higher contrast images of dental decay.

  13. Noncontact, nondestructive elasticity evaluation of sound and demineralized human dental enamel using a laser ultrasonic surface wave dispersion technique

    NASA Astrophysics Data System (ADS)

    Wang, Hsiao-Chuan; Fleming, Simon; Lee, Yung-Chun; Law, Susan; Swain, Michael; Xue, Jing

    2009-09-01

    Laser ultrasonic nondestructive evaluation (NDE) methods have been proposed to replace conventional in vivo dental clinical diagnosis tools that are either destructive or incapable of quantifying the elasticity of human dental enamel. In this work, a laser NDE system that can perform remote measurements on samples of small dimensions is presented. A focused laser line source is used to generate broadband surface acoustic wave impulses that are detected with a simplified optical fiber interferometer. The measured surface wave velocity dispersion spectrum is in turn used to characterize the elasticity of the specimen. The NDE system and the analysis technique are validated with measurements of different metal structures and then applied to evaluate human dental enamel. Artificial lesions are prepared on the samples to simulate different states of enamel elasticity. Measurement results for both sound and lesioned regions, as well as lesions of different severity, are clearly distinguishable from each other and fit well with physical expectations and theoretical value. This is the first time, to the best of our knowledge, that a laser-based surface wave velocity dispersion technique is successfully applied on human dental enamel, demonstrating the potential for noncontact, nondestructive in vivo detection of the development of carious lesions.

  14. The staining effect of different mouthwashes containing nanoparticles on dental enamel

    PubMed Central

    Eslami, Neda; Rajabi, Omid; Zamani, Roya

    2015-01-01

    Background This study aimed to evaluate the effects of several mouthwashes containing nanoparticles on discoloration of dental enamel, and compare the results with that of 0.2% chlorhexidine (CHX). Material and Methods Sixty intact premolars were randomly assigned to six groups. A spectrophotometer was used to measure the color of the teeth (T1) according to the CIELAB system. The specimens in groups 1 to 4 were then immersed in colloidal solutions containing nanoTiO2 (Group 1), nanoZnO (Group 2), nanoAg (Group 3) and nanoCuO (Group 4). In groups 5 and 6, a 0.2% CHX mouthwash and distilled water were used as positive and negative controls, respectively. After 24 hours of immersion, color determination was repeated (T2). The third color assessment was accomplished after brushing (T3). The L, a, and b values were recorded and the color change (?E) between different stages was calculated. Results ANOVA revealed significant between-group differences in the color change between T1 and T2 stages, as well as between T1 and T3 time points (p<0.05), whereas the color change between T2 and T3 was not significantly different among the study groups (p=0.09). ?ET1-T3 was significantly lower in the specimens immersed in distilled water or CHX as compared to the nanoparticle-containing mouthwashes (p<0.05). The highest ?E value pertained to the specimens immersed in nanoZnO-containing solution. The TiO2 nanoparticles caused the lowest staining among the tested nanoparticles. Conclusions The mouthwashes containing nanoparticles produced comparable or even greater enamel discoloration compared to CHX. Brushing had little effect on removal of induced stains. Key words:Nanoparticle, mouthrinse, mouthwash, staining, enamel, discoloration, chlorhexidine. PMID:26535089

  15. Analysis of the Early Stages and Evolution of Dental Enamel Erosion.

    PubMed

    Derceli, Juliana Dos Reis; Faraoni, Juliana Jendiroba; Pereira-da-Silva, Marcelo Assumpção; Palma-Dibb, Regina Guenka

    2016-01-01

    The aim of this study was to evaluate by atomic force microscopy (AFM) the early phases and evolution of dental enamel erosion caused by hydrochloric acid exposure, simulating gastroesophageal reflux episodes. Polished bovine enamel slabs (4x4x2 mm) were selected and exposed to 0.1 mL of 0.01 M hydrochloric acid (pH=2) at 37 ?#61472;?#61616;C using five different exposure intervals (n=1): no acid exposure (control), 10 s, 20 s, 30 s and 40 s. The exposed area was analyzed by AFM in 3 regions to measure the roughness, surface area and morphological surface. The data were analyzed qualitatively. Roughness started as low as that of the control sample, Rrms=3.5 nm, and gradually increased at a rate of 0.3 nm/s, until reaching Rrms=12.5 nm at 30 s. After 40 s, the roughness presented increment of 0.40 nm only. Surface area (SA) increased until 20 s, and for longer exposures, the surface area was constant (at 30 s, SA=4.40 μm2 and at 40 s, SA=4.43 μm2). As regards surface morphology, the control sample presented smaller hydroxyapatite crystals (22 nm) and after 40 s the crystal size was approximately 60 nm. Short periods of exposure were sufficient to produce enamel demineralization in different patterns and the morphological structure was less affected by exposure to hydrochloric acid over 30 s. PMID:27224566

  16. Evaluation of enamel by scanning electron microscopy green LED associated to hydrogen peroxide 35% for dental bleaching

    NASA Astrophysics Data System (ADS)

    Monteiro, Juliana S. C.; de Oliveira, Susana C. P. S.; Zanin, Fátima A. A.; Santos, Gustavo M. P.; Sampaio, Fernando J. P.; Gomes Júnior, Rafael Araújo; Gesteira, Maria F. M.; Vannier-Santos, Marcos A.; Pinheiro, Antônio Luiz B.

    2014-02-01

    Dental bleaching is a frequently requested procedure in clinical dental practice. The literature is contradictory regarding the effects of bleaching agents on both morphology and demineralization of enamel after bleaching. The aim of this study was to analyze by SEM the effect of 35% neutral hydrogen peroxide cured by green LED. Buccal surfaces of 15 pre-molars were sectioned and marked with a central groove to allow experimental and control groups on the same specimen. For SEM, 75 electron micrographs were evaluated by tree observers at 43X, 220X and 1000X. Quantitative analysis for the determination of the surface elemental composition of the samples through X-ray microanalysis by SEM was also performed. The protocol tested neither showed significant changes in mineral composition of the samples nor to dental enamel structure when compared to controls. SEM analysis allowed inferring that there were marked morphological differences between the enamel samples highlighting the need for the use of the same tooth in comparative morphological studies. The tested protocol did not cause morphological damage the enamel surface when compared to their respective controls.

  17. Research on optical properties of dental enamel for early caries diagnostics using a He-Ne laser

    NASA Astrophysics Data System (ADS)

    Tang, Jing; Liu, Li; Li, Song-zhan

    2008-12-01

    A new and non-invasive method adapted for optical diagnosis of early caries is proposed by researching on the interaction mechanism of laser with dental tissue and relations of remitted light with optical properties of the tissue. This method is based on simultaneous analyses of the following parameters: probing radiation, backscattering and auto-fluorescence. Investigation was performed on 104 dental samples in vitro by using He-Ne laser (λ=632.8nm, 2.0+/-0.1mW) as the probing. Spectrums of all samples were obtained. Characteristic spectrums of dental caries in various stages (intact, initial, moderate and deep) were given. Using the back-reflected light to normalize the intensity of back-scattering and fluorescence, a quantitative diagnosis standard for different stages of caries is proposed. In order to verify the test, comparison research was conducted among artificial caries, morphological damaged enamel, dental calculus and intact tooth. Results show that variations in backscattering characteristic changes in bio-tissue morphological and the quantity of auto-fluorescence is correlated with concentration of anaerobic microflora in hearth of caries lesion. This method poses a high potential of diagnosing various stages of dental caries, and is more reliability to detect early caries, surface damage of health enamel and dental calculus.

  18. The Impact of Stannous, Fluoride Ions and Its Combination on Enamel Pellicle Proteome and Dental Erosion Prevention

    PubMed Central

    Algarni, A. A.; Mussi, M. C. M.; Moffa, E. B.; Lippert, F.; Zero, D. T.; Siqueira, W. L.; Hara, A. T.

    2015-01-01

    Objectives To compare the effects of stannous (Sn) and fluoride (F) ions and their combination on acquired enamel pellicle (AEP) protein composition (proteome experiment), and protection against dental erosion (functional experiment). Methods In the proteome experiment, bovine enamel specimens were incubated in whole saliva supernatant for 24h for AEP formation. They were randomly assigned to 4 groups (n=10), according to the rinse treatment: Sn (800ppm/6.7mM, SnCl2), F (225ppm/13mM, NaF), Sn and F combination (Sn+F) and deionized water (DIW, negative control). The specimens were immersed 3× in the test rinses for 2min, 2h apart. Pellicles were collected, digested, and analyzed for protein content using liquid chromatography electrospray ionization tandem mass spectrometry. In the functional experiment, bovine enamel specimens (n=10) were similarly treated for pellicle formation. Then, they were subjected to a five-day erosion cycling model, consisting of 5min erosive challenges (15.6 mM citric acid, pH 2.6, 6×/d) and 2min treatment with the rinses containing Sn, F or Sn+F (3×/d). Between the treatments, all specimens were incubated in whole saliva supernatant. Surface loss was determined by profilometry. Results Our proteome approach on bovine enamel identified 72 proteins that were common to all groups. AEP of enamel treated with Sn+F demonstrated higher abundance for most of the identified proteins than the other groups. The functional experiment showed reduction of enamel surface loss for Sn+F (89%), Sn (67%) and F (42%) compared to DIW (all significantly different, p<0.05). Conclusion This study highlighted that anti-erosion rinses (e.g. Sn+F) can modify quantitatively and qualitatively the AEP formed on bovine enamel. Moreover, our study demonstrated a combinatory effect that amplified the anti-erosive protection on tooth surface. PMID:26030135

  19. Green LED associated to 20% hydrogen peroxide for dental bleaching: nanomorfologic study of enamel by scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Oliveira, Susana C. P. S.; Santos, Gustavo M. P.; Monteiro, Juliana S. C.; Sampaio, Fernando J. P.; Gesteira, Maria F. M.; Zanin, Fátima A. A.; Santos, Marcos A. V.; Pinheiro, Antônio L. B.

    2013-03-01

    Dental bleaching is a much requested procedure in clinical dental practice and widely related to dental esthetics. The literature is contradictory regarding the effects of bleaching agents on the morphology and demineralization of enamel after bleaching. The aim of this study was to analyze in vitro by scanning electron microscopy (SEM) the effect of hydrogen peroxide at 20% at neutral pH, cured by the green LED, to evaluate the action of these substances on dental enamel. We selected 15 pre-molars, lingual surfaces were sectioned and previously marked with a central groove to take the experimental and control groups on the same specimen. The groups were divided as follows. The mesial hemi-faces were the experimental group and distal ones as controls. For morphological analysis were performed 75 electron micrographs SEM with an increase of X 43, X 220 and X 1000 and its images were evaluated by tree observers. Was also performed quantitative analysis of the determination of the surface atomic composition of the samples through microanalysis with the aid of scanning electron microscopy. The use of hydrogen peroxide at a concentration of 20% at photoactivated green LED showed no significant changes in mineral composition of the samples or the dental morphological structure of the same when compared to their controls, according to the study protocol.

  20. Null mutation of chloride channel 7 (Clcn7) impairs dental root formation but does not affect enamel mineralization.

    PubMed

    Guo, Jing; Bervoets, Theodore J M; Henriksen, Kim; Everts, Vincent; Bronckers, Antonius L J J

    2016-02-01

    ClC-7, located in late endosomes and lysosomes, is critical for the function of osteoclasts. Secretion of Cl(-) by the ruffled border of osteoclasts enables H(+) secretion by v-H(+)-ATPases to dissolve bone mineral. Mice lacking ClC-7 show altered lysosomal function that leads to severe lysosomal storage. Maturation ameloblasts are epithelial cells with a ruffled border that secrete Cl(-) as well as endocytose and digest large quantities of enamel matrix proteins during formation of dental enamel. We tested the hypothesis that ClC-7 in maturation ameloblasts is required for intracellular digestion of matrix fragments to complete enamel mineralization. Craniofacial bones and developing teeth in Clcn7(-/-) mice were examined by micro-CT, immunohistochemistry, quantified histomorphometry and electron microscopy. Osteoclasts and ameloblasts in wild-type mice stained intensely with anti-ClC-7 antibody but not in Clcn7(-/-) mice. Craniofacial bones in Clcn7(-/-) mice were severely osteopetrotic and contained 1.4- to 1.6-fold more bone volume, which was less mineralized than the wild-type littermates. In Clcn7(-/-) mice maturation ameloblasts and osteoclasts highly expressed Ae2 as in wild-type mice. However, teeth failed to erupt, incisors were much shorter and roots were disfigured. Molars formed a normal dental crown. In compacted teeth, dentin was slightly less mineralized, enamel did not retain a matrix and mineralized fairly normal. We concluded that ClC-7 is essential for osteoclasts to resorb craniofacial bones to enable tooth eruption and root development. Disruption of Clcn7 reduces bone and dentin mineral density but does not affect enamel mineralization. PMID:26346547

  1. Matching the optical properties of direct esthetic dental restorative materials to those of human enamel and dentin

    NASA Astrophysics Data System (ADS)

    Ragain, James Carlton, Jr.

    One of the goals of the restorative dentist is to restore the appearance of the natural dentition. Clinical matching of teeth and restorative materials are seldom accurate and shade selection techniques are subjective. The first specific aim of this research was to characterize the optical absorption and scattering that occurs within enamel, dentin, and composite resin and compomer restorative materials and to relate those phenomena to translucency and color. The second aim was to evaluate small color differences among composite restorative materials which would be detectable by humans. The last aim was to lay the foundation for developing an improved model of specifying layers of dental restorative materials in order to match the translucency and color to those of human enamel. The Kubelka-Munk theory was validated for enamel, dentin, and the restorative materials. These tissues and materials were then characterized in terms of their color parameters. Tooth cores were also characterized in terms of color space parameters. Human subjects were evaluated for their abilities to discriminate small color differences in the dental composite resin materials. The following conclusions were derived from this study: (1) Kubelka-Munk theory accurately predicts the diffuse reflectance spectra of enamel, dentin, and the direct esthetic dental restorative materials studied. (2) Scattering and absorption coefficients of the dental tissues and esthetic restorative materials can be directly calculated from diffuse reflectance measurements of a uniformly thick slab of tissue/material using black and white backings and the appropriate refractive index. (3) For tooth cores, there is a positive correlation between L* and b* and a negative correlation between L* and a*. (4) The range of translucency parameters for the restorative materials studied does not match those of enamel and dentin. (5) None of the shades of the dental composite resin restorative materials studied fit into the

  2. Fluoride induces endoplasmic reticulum stress in ameloblasts responsible for dental enamel formation.

    PubMed

    Kubota, Kaori; Lee, Daniel H; Tsuchiya, Masahiro; Young, Conan S; Everett, Eric T; Martinez-Mier, Esperanza A; Snead, Malcolm L; Nguyen, Linh; Urano, Fumihiko; Bartlett, John D

    2005-06-17

    The mechanism of how fluoride causes fluorosis remains unknown. Exposure to fluoride can inhibit protein synthesis, and this may also occur by agents that cause endoplasmic reticulum (ER) stress. When translated proteins fail to fold properly or become misfolded, ER stress response genes are induced that together comprise the unfolded protein response. Because ameloblasts are responsible for dental enamel formation, we used an ameloblast-derived cell line (LS8) to characterize specific responses to fluoride treatment. LS8 cells were growth-inhibited by as little as 1.9-3.8 ppm fluoride, whereas higher doses induced ER stress and caspase-mediated DNA fragmentation. Growth arrest and DNA damage-inducible proteins (GADD153/CHOP, GADD45alpha), binding protein (BiP/glucose-responsive protein 78 (GRP78), the non-secreted form of carbonic anhydrase VI (CA-VI), and active X-box-binding protein-1 (Xbp-1) were all induced significantly after exposure to 38 ppm fluoride. Unexpectedly, DNA fragmentation increased when GADD153 expression was inhibited by short interfering RNA treatment but remained unaffected by transient GADD153 overexpression. Analysis of control and GADD153(-/-) embryonic fibroblasts demonstrated that caspase-3 mediated the increased DNA fragmentation observed in the GADD153 null cells. We also demonstrate that mouse incisor ameloblasts are sensitive to the toxic effects of high dose fluoride in drinking water. Activated Ire1 initiates an ER stress response pathway, and mouse ameloblasts were shown to express activated Ire1. Ire1 levels appeared induced by fluoride treatment, indicating that ER stress may play a role in dental fluorosis. Low dose fluoride, such as that present in fluoridated drinking water, did not induce ER stress. PMID:15849362

  3. Effects of continuous-wave CO2 laser on the ultrastructure of human dental enamel.

    PubMed

    Ferreira, J M; Palamara, J; Phakey, P P; Rachinger, W A; Orams, H J

    1989-01-01

    Laser-induced changes in plano-parallel sections were examined by light microscopy (LM) and scanning electron microscopy (SEM), and correlated with ultrastructural changes as observed by transmission electron microscopy (TEM). LM and SEM revealed two different changes--extensive crazing, and crazing and cratering. Rough exposed enamel was commonly found, resulting from lifting off and removal of the top layer of crazed, or crazed and cratered, enamel. The type of induced change was mainly dependent on the energy density used (range approximately 0.8 to approximately 200 J cm-2) and on enamel prism orientation. Lased enamel was also softer than unlased enamel. TEM of both crazed enamel and rough exposed enamel revealed that most crystals generally resembled those of unlased enamel in size and shape, but that inter- and intra-crystalline voids were present in some areas. The crazed and cratered enamel had significant ultrastructural changes: new homogeneous and inhomogeneous crystals of apatite with a different shape and larger size than those of the original, and a loss of prismatic structure. The lack of uniformity of the laser effect on crazed and cratered enamel was shown by variation in crystal packing (from good to poor), variations in crystal size from area to area, and the presence of pockets of poorly packed homogeneous crystals alongside pockets of well-packed inhomogeneous crystals. The crazing, crazing and cratering, rough exposed enamel and the greater number of voids, as well as the relative softness of lased enamel do not indicate an overall ultrastructural improvement. However, the larger apatite crystal size and loss of prismatic structure in crazed and cratered areas may partly explain previous observations of reduced rates of subsurface demineralization in lased enamel. PMID:2512902

  4. Dentist and practice characteristics associated with restorative treatment of enamel caries in permanent teeth: multiple-regression modeling of observational clinical data from The National Dental PBRN

    PubMed Central

    Fellows, Jeffrey L; Gordan, Valeria V.; Gilbert, Gregg H.; Rindal, D. Brad; Qvist, Vibeke; Litaker, Mark S.; Benjamin, Paul; Flink, Håkan; Pihlstrom, Daniel J.; Johnson, Neil

    2014-01-01

    Purpose Current evidence in dentistry recommends non-surgical treatment to manage enamel caries lesions. However, surveyed practitioners report they would restore enamel lesions that are confined to the enamel. We used actual clinical data to evaluate patient, dentist, and practice characteristics associated with restoration of enamel caries, while accounting for other factors. Methods We combined data from a National Dental Practice-Based Research Network observational study of consecutive restorations placed in previously unrestored permanent tooth surfaces and practice/demographic data from 229 participating network dentists. Analysis of variance and logistic regression, using generalized estimating equations (GEE) and variable selection within blocks, were used to test the hypothesis that patient, dentist, and practice characteristics were associated with variations in enamel restorations of occlusal and proximal caries compared to dentin lesions, accounting for dentist and patient clustering. Results Network dentists from 5 regions placed 6,891 restorations involving occlusal and/or proximal caries lesions. Enamel restorations accounted for 16% of enrolled occlusal caries lesions and 6% of enrolled proximal caries lesions. Enamel occlusal restorations varied significantly (p<0.05) by patient age and race/ethnicity, dentist use of caries risk assessment, network region, and practice type. Enamel proximal restorations varied significantly (p<0.05) by dentist race/ethnicity, network region, and practice type. CLINICAL SIGNIFICANCE Identifying patient, dentist, and practice characteristics associated with enamel caries restorations can guide strategies to improve provider adherence to evidence-based clinical recommendations. PMID:25000667

  5. Application of quantitative light-induced fluorescence to determine the depth of demineralization of dental fluorosis in enamel microabrasion: a case report

    PubMed Central

    Park, Tae-Young; Choi, Han-Sol; Ku, Hee-Won; Kim, Hyun-Su; Lee, Yoo-Jin

    2016-01-01

    Enamel microabrasion has become accepted as a conservative, nonrestorative method of removing intrinsic and superficial dysmineralization defects from dental fluorosis, restoring esthetics with minimal loss of enamel. However, it can be difficult to determine if restoration is necessary in dental fluorosis, because the lesion depth is often not easily recognized. This case report presents a method for analysis of enamel hypoplasia that uses quantitative light-induced fluorescence (QLF) followed by a combination of enamel microabrasion with carbamide peroxide home bleaching. We describe the utility of QLF when selecting a conservative treatment plan and confirming treatment efficacy. In this case, the treatment plan was based on QLF analysis, and the selected combination treatment of microabrasion and bleaching had good results. PMID:27508165

  6. Application of quantitative light-induced fluorescence to determine the depth of demineralization of dental fluorosis in enamel microabrasion: a case report.

    PubMed

    Park, Tae-Young; Choi, Han-Sol; Ku, Hee-Won; Kim, Hyun-Su; Lee, Yoo-Jin; Min, Jeong-Bum

    2016-08-01

    Enamel microabrasion has become accepted as a conservative, nonrestorative method of removing intrinsic and superficial dysmineralization defects from dental fluorosis, restoring esthetics with minimal loss of enamel. However, it can be difficult to determine if restoration is necessary in dental fluorosis, because the lesion depth is often not easily recognized. This case report presents a method for analysis of enamel hypoplasia that uses quantitative light-induced fluorescence (QLF) followed by a combination of enamel microabrasion with carbamide peroxide home bleaching. We describe the utility of QLF when selecting a conservative treatment plan and confirming treatment efficacy. In this case, the treatment plan was based on QLF analysis, and the selected combination treatment of microabrasion and bleaching had good results. PMID:27508165

  7. Shear bond strength and SEM morphology evaluation of different dental adhesives to enamel prepared with ER:YAG laser

    PubMed Central

    Pires, Patrícia T.; Ferreira, João C.; Oliveira, Sofia A.; Azevedo, Álvaro F.; Dias, Walter R.; Melo, Paulo R.

    2013-01-01

    Context: Early observations of enamel surfaces prepared by erbium lasers motivated clinicians to use laser as an alternative to chemical etching. Aims: Evaluate shear bond strength (SBS) values of different dental adhesives on Erbium:Yttrium Aluminum Garnet (Er:YAG) laser prepared enamel and to evaluate possible etching patterns correlations between dental adhesives and SBS values. Subjects and Methods: One hundred bovine incisors were randomly assigned to SBS tests on enamel (n = 15) and to enamel morphology analysis (n = 5) after Er:YAG laser preparation as follows: Group I – 37% phosphoric acid (PA)+ ExciTE®; Group II – ExciTE®; Group III – AdheSE® self-etching; Group IV – FuturaBond® no-rinse. NR; Group V – Xeno® V. Teeth were treated with the adhesive systems and subjected to thermal cycling. SBS were performed in a universal testing machine at 5 mm/min. Statistical Analysis Used: One-way ANOVA and post-hoc tests (P < 0.05). For the morphology evaluation, specimens were immersed in Ethylenediamine tetraacetic acid (EDTA) and the etching pattern analyzed under Scanning Electron Microscope (SEM). Results: Mean bond strengths were Group I – 47.17 ± 1.61 MPa (type I etching pattern); Group II – 32.56 ± 1.64 MPa, Group III – 29.10 ± 1.34 MPa, Group IV – 23.32 ± 1.53 MPa (type III etching pattern); Group V – 24.43 MPa ± 1.55 (type II etching pattern). Conclusions: Different adhesive systems yielded significantly different SBSs. Acid etching significantly increased the adhesion in laser treated enamel. No differences in SBS values were obtained between AdheSE® and ExciTE® without condition with PA. FuturaBond® NR and Xeno® V showed similar SBS, which was lower in comparison to the others adhesives. No correlation between enamel surface morphology and SBS values was observed, except when PA was used. PMID:23853447

  8. Effect of a new remineralizing biomaterial on the color of dental enamel.

    PubMed

    Vargas-Sánchez, Paula K; Delgado-Mejía, Edgar; Torres-Rodríguez, Carolina

    2014-01-01

    The aim of this research was to describe the effects of altering the composition of a modified remineralizing agent (MRA) and the osmotic pressure on tooth color by using spectrophotometric analysis. One hundred and four (104) human premolars and molars were randomly divided into 2 groups of 52 specimens each. Group 1 was treated with the remineralizing agent MRA 55, (remineralizing agent 1), a 50% - 50% by weight mixture of coarse-grain and fine-grain generating minerals, and group 2 was treated with the remineralizing agent MRA 91 (remineralizing agent 2), containing the same minerals in a 90% - 10% proportion. Each group was divided into 2 subgroups with 26 specimens each, which were stored as follows: subgroups A were stored in synthetic saliva with isotonic osmotic pressure (IP), and subgroups B in hypotonic osmotic pressure saliva (HP). The initial and final readings were taken with a Vita Easy Shade spectrophotometer. Color parameters (L*, a*, b*) and whiteness indices (WIC, WIO, W) were calculated from the readings. The color changes (deltaL, deltaA, deltaB, and deltaE) and whiteness indices were compared and analyzed with descriptive analyses. The variables deltaL, deltaA, deltaB, deltaE, and the whiteness index W were analyzed with an analysis of variance (ANOVA), and the indices WIC and WIO were analyzed with a nonparametric Kruskal-Wallis ANOVA. The results indicate that combination A2 (MRA 91 and IP) affected variables deltaB and deltaE, while combination B1 (MRA 55 and HP) affected variables deltaA, deltaB and the whiteness index WIO. Only MRA 91 affected the variable deltaL. The osmotic pressure of saliva and the remineralizing agent used affect the color of dental enamel. PMID:25335359

  9. Antibacterial effect of an enamel matrix protein derivative on in vivo dental biofilm vitality.

    PubMed

    Arweiler, Nicole Birgit; Auschill, Thorsten Mathias; Donos, Nikolaos; Sculean, Anton

    2002-12-01

    The purpose of this observer-blind, randomised, five-cell crossover study was to examine the antibacterial efficacy of an enamel matrix protein derivative (EMD) on established supragingival plaque in vivo. Saline (NaCl) served as a negative control solution and chlorhexidine (CHX) as a positive one. Additionally, the propylene glycol alginate (PGA) vehicle and the 24% ethylenediaminetetra-acetate (EDTA) gel were tested. After professional oral prophylaxis, 14 volunteers refrained from all mechanical oral hygiene measures for the following 48 h to build up plaque. In randomised order, the following procedures were applied: (a) 10 ml of CHX (0.2%) or (b) 10 ml of NaCl were used as a mouthrinse for 1 min each. In the cases of (c) EMD (Emdogain), (d) PGA, or (e) 24% EDTA (PrefGel), 1 ml of each were applied with a syringe on the teeth. Two hours after application, plaque samples were taken from one upper and one lower molar, and the vitality of the biofilm microbiota was examined using the vital fluorescence technique. Biofilm vitality (VF%) was lower for EMD, PGA, and CHX by 19% ( P<0.0001), 22% ( P=0.001), and 35% ( P<0.0001), respectively, than in negative controls. The EDTA showed similar vitality values to NaCl and was therefore not able to affect the biofilm flora significantly. The EMD and PGA displayed significantly reduced biofilm vitality compared to negative controls, which, however, could not reach the effect of the positive control (0.2% CHX). The present results demonstrate for the first time a direct influence of EMD on the vitality of supragingival dental plaque in vivo. PMID:12483234

  10. Evaluation of two imaging techniques: near-infrared transillumination and dental radiographs for the detection of early approximal enamel caries

    PubMed Central

    Maia, A M A; Karlsson, L; Margulis, W; Gomes, A S L

    2011-01-01

    Objectives The aim of this paper was to evaluate a transillumination (TI) system using near-infrared (NIR) light and bitewing radiographs for the detection of early approximal enamel caries lesions. Methods Mesiodistal sections of teeth (n = 14) were cut with various thicknesses from 1.5 mm to 4.75 mm. Both sides of each section were included, 17 approximal surfaces with natural enamel caries and 11 surfaces considered intact. The approximal surfaces were illuminated by NIR light and X-ray. Captured images were analysed by two calibrated specialists in radiology, and re-analysed after 6 months using stereomicroscope images as a gold standard. Results The interexaminer reliability (Kappa test statistic) for the NIR TI technique showed moderate agreement on first (0.55) and second (0.48) evaluation, and low agreement for bitewing radiographs on first (0.26) and second (0.32) evaluation. In terms of accuracy, the sensitivity for the NIR TI system was 0.88 and the specificity was 0.72. For the bitewing radiographs the sensitivity ranged from 0.35 to 0.53 and the specificity ranged from 0.50 to 0.72. Conclusion In the same samples and conditions tested, NIR TI images showed reliability and the enamel caries surfaces were better identified than on dental radiographs. PMID:21960400

  11. Optothermophysical properties of demineralized human dental enamel determined using photothermally generated diffuse photon density and thermal-wave fields.

    PubMed

    Hellen, Adam; Matvienko, Anna; Mandelis, Andreas; Finer, Yoav; Amaechi, Bennett T

    2010-12-20

    Noninvasive dental diagnostics is a growing discipline since it has been established that early detection and quantification of tooth mineral loss can reverse caries lesions in their incipient state. A theoretical coupled diffuse photon density and thermal-wave model was developed and applied to photothermal radiometric frequency responses, fitted to experimental data using a multiparameter simplex downhill minimization algorithm for the extraction of optothermophysical properties from artificially demineralized human enamel. The aim of this study was to evaluate the reliability and robustness of the advanced fitting algorithm. The results showed a select group of optical and thermal transport parameters and thicknesses were reliably extracted from the computational fitting algorithm. Theoretically derived thicknesses were accurately predicted, within about 20% error, while the estimated error in the optical and thermal property evaluation was within the values determined from early studies using destructive analyses. The high fidelity of the theoretical model illustrates its efficacy, reliability, and applicability toward the nondestructive characterization of depthwise inhomogeneous sound enamel and complex enamel caries lesions. PMID:21173829

  12. Effect of pretreatment with an Er:YAG laser and fluoride on the prevention of dental enamel erosion.

    PubMed

    dos Reis Derceli, Juliana; Faraoni-Romano, Juliana Jendiroba; Azevedo, Danielle Torres; Wang, Linda; Bataglion, César; Palma-Dibb, Regina Guenka

    2015-02-01

    The aim of this study was to evaluate the effect of the Er:YAG laser and its association with fluoride (1.23% acidulate phosphate fluoride gel) on the prevention of enamel erosion. Sixty specimens were obtained from bovine enamel (4 × 4 mm), which were ground flat, polished, and randomly divided into five groups according to the preventive treatments: control-fluoride application; L--Er:YAG laser; L+F--laser + fluoride; F+L--fluoride + laser; L/F--laser/fluoride simultaneously. Half of the enamel surface was covered with nail varnish (control area), and the other half was pretreated with one of the preventive strategies to subsequently be submitted to erosive challenge. When the laser was applied, it was irradiated for 10 s with a focal length of 4 mm and 60 mJ/2 Hz. Fluoride gel was applied for 4 min. Each specimen was individually exposed to regular Coca-Cola® for 1 min, four times/day, for 5 days. Wear analysis was performed with a profilometer, and demineralization was assessed with an optical microscope. Data were analyzed using the Kruskal-Wallis test (wear)/Dunn test and ANOVA/Fisher's exact tests. The group L/F was similar to control group. The other groups showed higher wear, which did not present differences among them. In the demineralization assessment, the groups F+L and L/F showed lower demineralization in relation to the other groups. It can be concluded that none preventive method was able to inhibit dental wear. The treatments L/F and F+L showed lower enamel demineralization. PMID:24149579

  13. Effects of enamel fluorosis and dental caries on quality of life.

    PubMed

    Onoriobe, U; Rozier, R G; Cantrell, J; King, R S

    2014-10-01

    The objectives of this study were to determine the impact of enamel fluorosis and dental caries on oral health-related quality of life (OHRQoL) in North Carolina schoolchildren and their families. Students (n = 7,686) enrolled in 398 classrooms in grades K-12 were recruited for a onetime survey. Parents of students in grades K-3 and 4-12 completed the Early Childhood Oral Health Impact Scale (ECOHIS) and Family Impact Scale (FIS), respectively. Students in grades 4-12 completed the Child Perceptions Questionnaire (CPQ8-10 in grades 4-5; CPQ11-14 in grades 6-12). All students were examined for fluorosis (Dean's index) and caries experience (d2-3fs or D2-3MFS indices). OHRQoL scores (sum response codes) were analyzed for their association with fluorosis categories and sum of d2-3fs and D2-3MFS according to ordinary least squares regression with SAS procedures for multiple imputation and analysis of complex survey data. Differences in OHRQoL scores were evaluated against statistical and minimal important difference (MID) thresholds. Of 5,484 examined students, 71.8% had no fluorosis; 24.4%, questionable to very mild fluorosis; and 3.7%, mild, moderate, or severe fluorosis. Caries categories were as follows: none (43.1%), low (28.6%), and moderate to high (28.2%). No associations between fluorosis and any OHRQoL scales met statistical or MID thresholds. The difference (5.8 points) in unadjusted mean ECOHIS scores for the no-caries and moderate-to-high caries groups exceeded the MID estimate (2.7 points) for that scale. The difference in mean FIS scores (1.5 points) for the no-caries and moderate-to-high groups exceeded the MID value (1.2 points). The sum of d2-3fs and D2-3MFS scores was positively associated with CPQ11-14 (B = 0.240, p < .001), ECOHIS (B = 0.252, p ≤ .001), and FIS (B = 0.096, p ≤ .01) scores in ordinary least squares regression models. A child's caries experience negatively affects OHRQoL, while fluorosis has little impact. PMID:25154834

  14. Effects of Enamel Fluorosis and Dental Caries on Quality of Life

    PubMed Central

    Onoriobe, U.; Rozier, R.G.; Cantrell, J.; King, R.S.

    2014-01-01

    The objectives of this study were to determine the impact of enamel fluorosis and dental caries on oral health–related quality of life (OHRQoL) in North Carolina schoolchildren and their families. Students (n = 7,686) enrolled in 398 classrooms in grades K-12 were recruited for a onetime survey. Parents of students in grades K-3 and 4-12 completed the Early Childhood Oral Health Impact Scale (ECOHIS) and Family Impact Scale (FIS), respectively. Students in grades 4-12 completed the Child Perceptions Questionnaire (CPQ8-10 in grades 4-5; CPQ11-14 in grades 6-12). All students were examined for fluorosis (Dean’s index) and caries experience (d2-3fs or D2-3MFS indices). OHRQoL scores (sum response codes) were analyzed for their association with fluorosis categories and sum of d2-3fs and D2-3MFS according to ordinary least squares regression with SAS procedures for multiple imputation and analysis of complex survey data. Differences in OHRQoL scores were evaluated against statistical and minimal important difference (MID) thresholds. Of 5,484 examined students, 71.8% had no fluorosis; 24.4%, questionable to very mild fluorosis; and 3.7%, mild, moderate, or severe fluorosis. Caries categories were as follows: none (43.1%), low (28.6%), and moderate to high (28.2%). No associations between fluorosis and any OHRQoL scales met statistical or MID thresholds. The difference (5.8 points) in unadjusted mean ECOHIS scores for the no-caries and moderate-to-high caries groups exceeded the MID estimate (2.7 points) for that scale. The difference in mean FIS scores (1.5 points) for the no-caries and moderate-to-high groups exceeded the MID value (1.2 points). The sum of d2-3fs and D2-3MFS scores was positively associated with CPQ11-14 (B = 0.240, p < .001), ECOHIS (B = 0.252, p ≤ .001), and FIS (B = 0.096, p ≤ .01) scores in ordinary least squares regression models. A child’s caries experience negatively affects OHRQoL, while fluorosis has little impact. PMID:25154834

  15. Amelogenin and Enamel Biomimetics

    PubMed Central

    Ruan, Qichao; Moradian-Oldak, Janet

    2015-01-01

    Mature tooth enamel is acellular and does not regenerate itself. Developing technologies that rebuild tooth enamel and preserve tooth structure is therefore of great interest. Considering the importance of amelogenin protein in dental enamel formation, its ability to control apatite mineralization in vitro, and its potential to be applied in fabrication of future bio-inspired dental material this review focuses on two major subjects: amelogenin and enamel biomimetics. We review the most recent findings on amelogenin secondary and tertiary structural properties with a focus on its interactions with different targets including other enamel proteins, apatite mineral, and phospholipids. Following a brief overview of enamel hierarchical structure and its mechanical properties we will present the state-of-the-art strategies in the biomimetic reconstruction of human enamel. PMID:26251723

  16. Amorphous intergranular phases control the properties of rodent tooth enamel

    NASA Astrophysics Data System (ADS)

    Gordon, Lyle M.; Cohen, Michael J.; MacRenaris, Keith W.; Pasteris, Jill D.; Seda, Takele; Joester, Derk

    2015-02-01

    Dental enamel, a hierarchical material composed primarily of hydroxylapatite nanowires, is susceptible to degradation by plaque biofilm-derived acids. The solubility of enamel strongly depends on the presence of Mg2+, F-, and CO32-. However, determining the distribution of these minor ions is challenging. We show—using atom probe tomography, x-ray absorption spectroscopy, and correlative techniques—that in unpigmented rodent enamel, Mg2+ is predominantly present at grain boundaries as an intergranular phase of Mg-substituted amorphous calcium phosphate (Mg-ACP). In the pigmented enamel, a mixture of ferrihydrite and amorphous iron-calcium phosphate replaces the more soluble Mg-ACP, rendering it both harder and more resistant to acid attack. These results demonstrate the presence of enduring amorphous phases with a dramatic influence on the physical and chemical properties of the mature mineralized tissue.

  17. Sub-10-micrometer toughening and crack tip toughness of dental enamel.

    PubMed

    Ang, Siang Fung; Schulz, Anja; Pacher Fernandes, Rodrigo; Schneider, Gerold A

    2011-04-01

    In previous studies, enamel showed indications to occlude small cracks in-vivo and exhibited R-curve behaviors for bigger cracks ex-vivo. This study quantifies the crack tip's toughness (K(I0),K(III0)), the crack's closure stress and the cohesive zone size at the crack tip of enamel and investigates the toughening mechanisms near the crack tip down to the length scale of a single enamel crystallite. The crack-opening-displacement (COD) profile of cracks induced by Vickers indents on mature bovine enamel was studied using atomic force microscopy (AFM). The mode I crack tip toughness K(I0) of cracks along enamel rod boundaries and across enamel rods exhibit a similar range of values: K(I0,Ir)=0.5-1.6MPa m(0.5) (based on Irwin's 'near-field' solution) and K(I0,cz)=0.8-1.5MPa m(0.5) (based on the cohesive zone solution of the Dugdale-Muskhelishvili (DM) crack model). The mode III crack tip toughness K(III0,Ir) was computed as 0.02-0.15MPa m(0.5). The crack-closure stress at the crack tip was computed as 163-770 MPa with a cohesive zone length and width 1.6-10.1μm and 24-44 nm utilizing the cohesive zone solution. Toughening elements were observed under AFM and SEM: crack bridging due to protein ligament and hydroxyapatite fibres (micro- and nanometer scale) as well as microcracks were identified. PMID:21316630

  18. Surface variations affecting human dental enamel studied using nanomechanical and chemical analysis

    NASA Astrophysics Data System (ADS)

    Dickinson, Michelle Emma

    The enamel surface is the interface between the tooth and its ever changing oral environment. Cavity (caries) formation and extrinsic tooth staining are due, respectively, to degradation of the enamel structure under low pH conditions and interactions between salivary pellicle and dietary elements. Both of these occur at the enamel surface and are caused by the local environment changing the chemistry of the surface. The results can be detrimental to the enamel's mechanical integrity and aesthetics. Incipient carious lesions are the precursor to caries and form due to demineralisation of enamel. These carious lesions are a reversible structure where ions (e.g. Ca2+, F -) can diffuse in (remineralisation) to preserve the tooth's structural integrity. This investigation used controlled in vitro demineralisation and remineralisation to study artificial carious lesion formation and repair. The carious lesions were cross-sectioned and characterised using nanoindentation, electron probe micro-analysis and time of flight secondary ion mass spectrometry. Mechanical and chemical maps showed the carious lesion had a significantly reduced hardness and elastic modulus, and the calcium and phosphate content was lower than in sound enamel. Fluoride based remineralisation treatments gave a new phase (possibly fluorohydroxyapatite) within the lesion with mechanical properties higher than sound enamel. The acquired salivary pellicle is a protein-rich film formed by the physisorption of organic molecules in saliva onto the enamel surface. Its functions include lubrication during mastication and chemical protection. However, pellicle proteins react with dietary elements such as polyphenols (tannins in tea) causing a brown stain. This study has used in vitro dynamic nanoindentation and atomic force microscopy to examine normal and stained pellicles formed in vivo. The effects of polyphenols on the pellicle's mechanical properties and morphology have been studied. It was found that the

  19. Comparison of bond strength and surface morphology of dental enamel for acid and Nd-YAG laser etching

    NASA Astrophysics Data System (ADS)

    Parmeswearan, Diagaradjane; Ganesan, Singaravelu; Ratna, P.; Koteeswaran, D.

    1999-05-01

    Recently, laser pretreatment of dental enamel has emerged as a new technique in the field of orthodontics. However, the changes in the morphology of the enamel surface is very much dependent on the wavelength of laser, emission mode of the laser, energy density, exposure time and the nature of the substance absorbing the energy. Based on these, we made a comparative in vitro study on laser etching with acid etching with reference to their bond strength. Studies were conducted on 90 freshly extracted, non carious, human maxillary or mandibular anteriors and premolars. Out of 90, 60 were randomly selected for laser irradiation. The other 30 were used for conventional acid pretreatment. The group of 60 were subjected to Nd-YAG laser exposure (1060 nm, 10 Hz) at differetn fluences. The remaining 30 were acid pretreated with 30% orthophosphoric acid. Suitable Begg's brackets were selected and bound to the pretreated surface and the bond strength were tested using Instron testing machine. The bond strength achieved through acid pretreatment is found to be appreciably greater than the laser pretreated tooth. Though the bond strength achieved through the acid pretreated tooth is found to be significantly greater than the laser pretreated specimens, the laser pretreatement is found to be successful enough to produce a clinically acceptable bond strength of > 0.60 Kb/mm. Examination of the laser pre-treated tooth under SEM showed globule formation which may produce the mechanical interface required for the retention of the resin material.

  20. Histomorphometric and microchemical characterization of maturing dental enamel in rats fed a boron-deficient diet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Few reports are available in the literature on enamel formation under nutritional deficiencies. Continuously erupting rodent incisors have considerable potential to serve as a model system for amelogenesis. Thus, we performed a study to determine the effects of boron (B) deficiency on the maturing d...

  1. An in vitro investigation of the effect of some analgesics on human enamel.

    PubMed

    McNally, L M; Barbour, M E; O'Sullivan, D J; Jagger, D C

    2006-07-01

    The sale of over-the-counter pain relief medication has increased dramatically in recent years, and typically amounts to several hundred thousands of pounds per year in the UK. Many soluble analgesic preparations contain citric acid, and it has been suggested that these formulations may cause dental erosion. The aim of this study was to investigate the effect of some over-the-counter analgesics on tooth surface loss from human enamel. Six commonly available analgesics were chosen for this study and the effect of immersing unerupted human enamel was examined using non-contact optical profilometry. Two of the six analgesics investigated caused no detectable erosion (Boots soluble aspirin and Anadin Extra). Three caused statistically significant enamel erosion, but this was very slight and is thought to be clinically insignificant (Alka Seltzer, Panadol and Solpadeine). Only one analgesic caused possible potentially clinical significant enamel erosion. Further studies are needed to determine whether Aspro causes clinically significant enamel erosion. PMID:16774512

  2. Ameloblasts require active RhoA to generate normal dental enamel

    PubMed Central

    Li, Yong; Xue, Hui; Everett, Eric T.; Ryan, Kathleen; Peng, Li; Porecha, Rakhee; Yan, Yan; Lucchese, Anna M.; Kuehl, Melissa A.; Pugach, Megan K.; Bouchard, Jessica; Gibson, Carolyn W.

    2013-01-01

    RhoA plays a fundamental role in regulation of the actin cytoskeleton, intercellular attachment and cell proliferation. During amelogenesis, ameloblasts which produce the enamel proteins undergo dramatic cytoskeletal changes and RhoA protein level is upregulated. Transgenic mice were generated that express a dominant-negative RhoA transgene in ameloblasts using amelogenin gene regulatory sequences. Transgenic and WT molar tooth germs were incubated with NaF or NaCl in organ culture. F-actin stained with phalloidin was elevated significantly in WT ameloblasts treated with NaF compared to WT ameloblasts treated with NaCl or compared to transgenic ameloblasts treated with NaF, thereby confirming a block in the RhoA/ROCK pathway in the transgenic mice. Little difference in quantitative fluorescence (estimation of fluorosis) was observed between WT and transgenic incisors from mice provided NaF in their drinking water. We subsequently found reduced transgene expression in incisors compared to molars. Transgenic molar teeth had reduced amelogenin, E-cadherin and Ki67 compared to WT. Hypoplastic enamel in transgenic mice correlates with reduced expression of the enamel protein amelogenin, and E-cadherin and cell proliferation are regulated by RhoA in other tissues. Together these findings reveal deficits in molar ameloblast function when RhoA activity is inhibited. PMID:23841780

  3. Structural changes in fluorosed dental enamel of red deer (Cervus elaphus L.) from a region with severe environmental pollution by fluorides.

    PubMed Central

    Kierdorf, U; Kierdorf, H; Sedlacek, F; Fejerskov, O

    1996-01-01

    A macroscopic, microradiographic and scanning electron microscope study was performed on the structure of fluorosed dental enamel in red deer from a fluoride polluted region (North Bohemia, Czech Republic). As was revealed by analysis of mandibular bone fluoride content, the rate of skeletal fluoride accumulation in the fluorotic deer was about 6 times that in controls taken from a region not exposed to excessive fluoride deposition. In all fluorosed mandibles, the 1st molar was consistently less fluorotic than the other permanent teeth. This was related to the fact that crown formation in the M1 takes place prenatally and during the lactation period. Fluorosed teeth exhibited opaque and posteruptively stained enamel, reduction or loss of enamel ridges, moderately to grossly increased wear and, in more severe cases, also enamel surface lesions of partly posteruptive, partly developmental origin. Microradiographically, fluorosed enamel was characterised by subsurface hypomineralisation, interpreted as a result of fluoride interference with the process of enamel maturation. In addition, an accentuation of the incremental pattern due to the occurrence of alternating bands with highly varying mineral content was observed in severely fluorosed teeth, denoting fluoride disturbance during the secretory stage of amelogenesis. A corresponding enhancement of the incremental pattern was also seen in the dentine. The enamel along the more pronounced hypoplasias consisted of stacked, thin layers of crystals arranged in parallel, indicating that the ameloblasts in these locations had lost the distal (prism-forming) portions of their Tomes processes. The findings of the present study indicate that red deer are highly sensitive bioindicators of environmental pollution by fluorides. Images Figs 2-9 Fig. 10 Fig. 11 Fig. 12 Fig. 13 Fig. 14 Fig. 15 Fig. 16 Fig. 17 Fig. 18 Fig. 19 Fig. 20 Fig. 21 Fig. 22 Fig. 23 Fig. 24 Fig. 25 Fig. 26 PMID:8655406

  4. Fluorine uptake into human enamel around a fluoride-containing dental material during cariogenic pH cycling

    NASA Astrophysics Data System (ADS)

    Komatsu, H.; Yamamoto, H.; Nomachi, M.; Yasuda, K.; Matsuda, Y.; Murata, Y.; Kijimura, T.; Sano, H.; Sakai, T.; Kamiya, T.

    2007-07-01

    the enamel adjacent to the material remained a caries inhibition zone due to low rate of demineralization. With caries progression, fluorine accumulated in the subsurface of the caries lesion, while the outermost surface of the caries lesion gradually dissolved under increasing pH cycling. The data obtained using PIGE (TIARA, JAPAN) technique were useful to understand the fluorine benefit for preventing dental caries by means of fluoride-containing dental materials.

  5. 3D scanning electron microscopy applied to surface characterization of fluorosed dental enamel.

    PubMed

    Limandri, Silvina; Galván Josa, Víctor; Valentinuzzi, María Cecilia; Chena, María Emilia; Castellano, Gustavo

    2016-05-01

    The enamel surfaces of fluorotic teeth were studied by scanning electron stereomicroscopy. Different whitening treatments were applied to 25 pieces to remove stains caused by fluorosis and their surfaces were characterized by stereomicroscopy in order to obtain functional and amplitude parameters. The topographic features resulting for each treatment were determined through these parameters. The results obtained show that the 3D reconstruction achieved from the SEM stereo pairs is a valuable potential alternative for the surface characterization of this kind of samples. PMID:26930005

  6. Artificial caries produced by different oral bacterial cultures incubated with bovine dental enamel.

    PubMed

    Gallagher, I H; Pearce, E I; Cutress, T W

    1983-01-01

    Early caries-like lesions were formed in enamel incubated in glucose broths inoculated with different cultures of oral bacteria. Analysis of the broths by gas chromatography revealed, after appropriate incubation, the presence of lactic, succinic, formic, acetic, propionic, isobutyric, n-butyric, isovaleric or n-caproic or mixtures of these acid catabolites. Subsurface lesions formed with all acids and mixtures providing that the terminal pH dropped less than or equal to 5.6. However, the processes conformed in part only with the idealized simple diffusion phenomenon for caries formation, indicating the presence of other factors which could affect the production of lesions in biological systems. PMID:6349592

  7. Adhesion of polycarboxylate-based dental cements to enamel: an in vivo study.

    PubMed

    Jemt, T; Stålblad, P A; Oilo, G

    1986-06-01

    The bond strength of two polycarboxylate and two glass ionomer cements to enamel in vivo has been measured by a tensile test method. The four cements were used to cement small stainless steel cylinders onto the facial surfaces of 11 and 21. The cylinders were removed by a tensile force applied by a handpiece containing a semi-conductor sensory unit. The results showed that all cements gave two sets of bond strength values, either a good bond corresponding to a cohesive failure, or a weak bond corresponding to an adhesive failure. The mean bond strength values were lower than those recorded in vitro, and differences among the cements were limited. PMID:3519712

  8. Influence of acid-etched splinting methods on discoloration of dental enamel in four media: an in vitro study.

    PubMed

    Oikarinen, K S; Nieminen, T M

    1994-12-01

    The aim of this in vitro study was to assess the staining of enamel in relation to fixation of luxated teeth. Color changes induced by chlorhexidine, red wine, tea, and coffee were detected with a Minolta Chroma Meter (CR-121) after extracted teeth were treated to simulate construction of dental splinting. L*a*b* color readings were made before and after 7 days of incubation in the above-mentioned media in teeth treated 1) by acid-etching, 2) by acid-etching followed by resin, 3) by resin and composite, 4) by Triad Gel, and 5) by Protemp. L* is an indicator of black (0) and white (100). The a* values relate to the red (+100)-green (-100) color axes, and the b* values to the yellow (+100) and blue (-100) axes. Untreated teeth served as controls. One-way analysis of variance of mean L* values revealed no statistically significant differences in treatment. Discoloration was observed in all teeth, including the control ones. However, Protemp yielded the largest changes in mean L* values. Analysis of variance of mean L* values revealed statistically significant differences between incubation liquids because no increase in staining of enamel was noted after 7 days' incubation in chlorhexidine. Red wine increased the mean L* values more than coffee or tea. Changes in a*b* readings were toward red (+a*) after incubation in red wine, except in the case of teeth treated with resin. The color of all such teeth changed more toward yellow (+b*), because the resin used was yellow.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7871352

  9. Some epidemiological and scanning electron microscopic features of crazing of the dental enamel of Polynesians.

    PubMed

    Hoffman, M P; Cutress, T W; Crooks, M C

    1989-07-01

    The prevalence of enamel crazing was determined from the maxillary incisors and canines of 1,109 Tongan residents aged 5-20 years, 1,417 Cook Island residents aged 6-20 years, 520 French Polynesian residents aged 10-15 years, and 92 New Zealand-born and -resident Polynesians aged 11-18 years. Crazing occurred in 22 percent of Tongans, 7 percent of Cook Islanders, but not in French Polynesians or New Zealand-born Polynesians. Cracks become clinically apparent at about 8 years of age; were more common in males than females; and became more common with increasing age. The central incisors were the most commonly affected of the maxillary anterior teeth. Cross-sections of teeth with crazing viewed by light and scanning electron microscopy appeared similar to other stained cracks. The indications are that crazing is a post-eruptive change caused by trauma from local environmental factors resulting in stress fractures. The significance of crazing on enamel structure and strength is unknown, but it is probably minor without long-term disadvantages. The prevalence of crazing may prove useful in anthropology as an indicator of the use of teeth as tools and in assessing the "modernisation" of a population. PMID:2788843

  10. Paleoenvironmental conditions in the Spanish Miocene-Pliocene boundary: isotopic analyses of Hipparion dental enamel.

    PubMed

    Domingo, Laura; Grimes, Stephen T; Domingo, M Soledad; Alberdi, M Teresa

    2009-04-01

    Expansion of C(4) grasses during Late Miocene and Early Pliocene constitutes one of the most remarkable biotic events of the Cenozoic era. The Teruel-Alfambra region (northeastern Spain) contains one of the most complete Miocene-Pliocene sequences of mammalian fossil sites in the world. In this study, stable isotope (delta (13)C and delta (18)O) analyses have been performed on the tooth enamel from the equid Hipparion from 19 localities spanning a time interval from approximately 10.9 to 2.7 Ma. This time range starts with the first appearance of this genus in Spain and ends at its extinction. An increase in delta (13)C at about 4.2 Ma has been observed, indicative of a shift toward a more open habitat. This shift may be related to a large scale vegetation change which occurred across the Miocene-Pliocene boundary when C(4) grasses expanded. This expansion might in turn be linked to global tectonic events such as the uplift of the Himalaya and/or the closure of the Panama Isthmus. However, other more regional factors may have ultimately enhanced the trend toward more open habitats in the Western Mediterranean Basin. The Messinian Salinity Crisis was a major environmental event that may have been responsible for the isotopic changes seen in the equid Hipparion from the Iberian Peninsula along with an increase in the aridity detected approximately 4.6 Ma ago in the Sahara. Even though the exact factor triggering the isotopic change observed in the Hipparion enamel remains mostly unknown, this study demonstrates that the global environmental changes detected across the Miocene-Pliocene boundary are also recorded in the realm of the Iberian Peninsula. PMID:19190888

  11. Clinical cross-polarization optical coherence tomography assessment of subsurface enamel below dental resin composite restorations

    PubMed Central

    Lenton, Patricia; Rudney, Joel; Fok, Alex; Jones, Robert S.

    2014-01-01

    Abstract. A newly designed intraoral swept source cross-polarization optical coherence tomography (CP-OCT) imaging system was used to examine the integrity of the subsurface enamel below resin composite restorations placed in primary teeth. CP-OCT analysis was performed using images obtained from resin composite restoration in 62 (n=62) pediatric subjects. Clinical examination was performed by a single examiner prior to CP-OCT imaging and analysis. CP-OCT images are presented using a unique combined intensity image, where a false color scale is overlaid on the grayscale intensity image. There was a clear difference in the distribution of the mean-backscattered intensity (mR) between restorations recently placed and those possessing frank cavitation (Student’s t-test, P<0.0001). For mR above 15.49 dB, the sensitivity was 80% and specificity 86%. The Youden index J was 0.8 above 12.3 dB where sensitivity was 100% and specificity was 80%. CP-OCT imaging may be used to confirm the subsurface marginal integrity below resin composite restorations but with careful consideration of limitations of the imaging modality. CP-OCT imaging may be a useful adjunct to clinical visual investigation to confirm that a composite margin has a sound and well-adapted interface. PMID:26158031

  12. Clinical cross-polarization optical coherence tomography assessment of subsurface enamel below dental resin composite restorations.

    PubMed

    Lenton, Patricia; Rudney, Joel; Fok, Alex; Jones, Robert S

    2014-04-01

    A newly designed intraoral swept source cross-polarization optical coherence tomography (CP-OCT) imaging system was used to examine the integrity of the subsurface enamel below resin composite restorations placed in primary teeth. CP-OCT analysis was performed using images obtained from resin composite restoration in 62 ([Formula: see text]) pediatric subjects. Clinical examination was performed by a single examiner prior to CP-OCT imaging and analysis. CP-OCT images are presented using a unique combined intensity image, where a false color scale is overlaid on the grayscale intensity image. There was a clear difference in the distribution of the mean-backscattered intensity (mR) between restorations recently placed and those possessing frank cavitation (Student's t-test, [Formula: see text]). For mR above 15.49 dB, the sensitivity was 80% and specificity 86%. The Youden index J was 0.8 above 12.3 dB where sensitivity was 100% and specificity was 80%. CP-OCT imaging may be used to confirm the subsurface marginal integrity below resin composite restorations but with careful consideration of limitations of the imaging modality. CP-OCT imaging may be a useful adjunct to clinical visual investigation to confirm that a composite margin has a sound and well-adapted interface. PMID:26158031

  13. Spectrophotometric evaluation of dental bleaching under orthodontic bracket in enamel and dentin

    PubMed Central

    Correr, Americo-Bortolazzo; Rastelli, Alessandra-Nara-Souza; Lima, Débora-Alves-Nunes-Leite; Consani, Rafael-Leonardo-Xediek

    2014-01-01

    Aware of the diffusion capacity of bleaching in the dental tissues, many orthodontists are subjecting their patients to dental bleaching during orthodontic treatment for esthetic purposes or to anticipate the exchange of esthetic restorations after the orthodontic treatment. For this purpose specific products have been developed in pre-loaded whitening trays designed to fit over and around brackets and wires, with clinical efficacy proven. Objective: The objective of this study was to evaluate, through spectrophotometric reflectance, the effectiveness of dental bleaching under orthodontic bracket. Material and Methods: Thirty-two bovine incisors crown blocks of 8 mm x 8 mm height lengths were used. Staining of tooth blocks with black tea was performed for six days. They were distributed randomly into 4 groups (1-home bleaching with bracket, 2- home bleaching without bracket, 3- office bleaching with bracket, 4 office bleaching without bracket). The color evaluation was performed (CIE L * a * b *) using color reflectance spectrophotometer. Metal brackets were bonded in groups 1 and 3. The groups 1 and 2 samples were subjected to the carbamide peroxide at 15%, 4 hours daily for 21 days. Groups 3 and 4 were subjected to 3 in-office bleaching treatment sessions, hydrogen peroxide 38%. After removal of the brackets, the second color evaluation was performed in tooth block, difference between the area under the bracket and around it, and after 7 days to verified color stability. Data analysis was performed using the paired t-test and two-way variance analysis and Tukey’s. Results: The home bleaching technique proved to be more effective compared to the office bleaching. There was a significant difference between the margin and center color values of the specimens that were subjected to bracket bonding. Conclusions: The bracket bond presence affected the effectiveness of both the home and office bleaching treatments. Key words:Tooth bleaching, spectrophotometry

  14. A simple, sensitive and non-destructive technique for characterizing bovine dental enamel erosion: attenuated total reflection Fourier transform infrared spectroscopy.

    PubMed

    Kim, In-Hye; Son, Jun Sik; Min, Bong Ki; Kim, Young Kyoung; Kim, Kyo-Han; Kwon, Tae-Yub

    2016-01-01

    Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Deionized water (control) and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth (110) were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 °C. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers' microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ν1, ν3 phosphate contour: the ratio of the height amplitude of ν3 PO4 to that of ν1 PO4 (Method 1) and the shift of the ν3 PO4 peak to a higher wavenumber (Method 2). The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy (P<0.001). Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR-FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion. PMID:27025266

  15. A simple, sensitive and non-destructive technique for characterizing bovine dental enamel erosion: attenuated total reflection Fourier transform infrared spectroscopy

    PubMed Central

    Kim, In-Hye; Son, Jun Sik; Min, Bong Ki; Kim, Young Kyoung; Kim, Kyo-Han; Kwon, Tae-Yub

    2016-01-01

    Although many techniques are available to assess enamel erosion in vitro, a simple, non-destructive method with sufficient sensitivity for quantifying dental erosion is required. This study characterized the bovine dental enamel erosion induced by various acidic beverages in vitro using attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Deionized water (control) and 10 acidic beverages were selected to study erosion, and the pH and neutralizable acidity were measured. Bovine anterior teeth (110) were polished with up to 1 200-grit silicon carbide paper to produce flat enamel surfaces, which were then immersed in 20 mL of the beverages for 30 min at 37 °C. The degree of erosion was evaluated using ATR-FTIR spectroscopy and Vickers' microhardness measurements. The spectra obtained were interpreted in two ways that focused on the ν1, ν3 phosphate contour: the ratio of the height amplitude of ν3 PO4 to that of ν1 PO4 (Method 1) and the shift of the ν3 PO4 peak to a higher wavenumber (Method 2). The percentage changes in microhardness after the erosion treatments were primarily affected by the pH of the immersion media. Regression analyses revealed highly significant correlations between the surface hardness change and the degree of erosion, as detected by ATR-FTIR spectroscopy (P<0.001). Method 1 was the most sensitive to these changes, followed by surface hardness change measurements and Method 2. This study suggests that ATR-FTIR spectroscopy is potentially advantageous over the microhardness test as a simple, non-destructive, sensitive technique for the quantification of enamel erosion. PMID:27025266

  16. Evaluation of microshear bond strength of resin composites to enamel of dental adhesive systems associated with Er,Cr:YSGG laser

    NASA Astrophysics Data System (ADS)

    Cassimiro-Silva, Patricia F.; Zezell, Denise M.; Monteiro, Gabriela Q. d. M.; Benetti, Carolina; de Paula Eduardo, Carlos; Gomes, Anderson S. L.

    2016-02-01

    The aim of this in vitro study was to evaluate the microshear bond strength (μSBS) of resin composite to enamel etching by Er,Cr:YSGG laser with the use of two differents adhesives systems. Fifty freshly extracted human molars halves were embedded in acrylic resin before preparation for the study, making a total of up to 100 available samples. The specimens were randomly assigned into six groups (η=10) according to substrate pre-treatment and adhesive system on the enamel. A two-step self-etching primer system (Clearfil SE Bond) and a universal adhesive used as an etch-andrinse adhesive (Adper Single Bond Universal) were applied to the nonirradiated enamel surface according to manufacturer's instructions, as control groups (Control CF and Control SB, respectively). For the other groups, enamel surfaces were previously irradiated with the Er,Cr:YSGG laser with 0.5 W, 75 mJ and 66 J/cm2 (CF 5 Hz and SB 5 Hz) and 1.25 W, 50 mJ and 44 J/cm2 (CF 15 Hz and SB 15 Hz). Irradiation was performed under air (50%) and water (50%) cooling. An independent t-test was performed to compare the adhesive systems. Mean μSBS ± sd (MPa) for each group was 16.857 +/- 2.61, 17.87 +/- 5.83, 12.23 +/- 2.02, 9.88 +/- 2.26, 15.94 +/- 1.98, 17.62 +/- 2.10, respectively. The control groups and the 50 mJ laser groups showed no statistically significant differences, regardless of the adhesive system used. The results obtained lead us to affirm that the bonding interaction of adhesives to enamel depends not only on the morphological aspects of the dental surface, but also on the characteristics of the adhesive employed and the parameters of the laser.

  17. Antibacterial effect of water-soluble chitosan on representative dental pathogens Streptococcus mutans and Lactobacilli brevis

    PubMed Central

    CHEN, Chih-YU; CHUNG, Ying-CHIEN

    2012-01-01

    Dental caries is still a major oral health problem in most industrialized countries. The development of dental caries primarily involves Lactobacilli spp. and Streptococcus mutans. Although antibacterial ingredients are used against oral bacteria to reduce dental caries, some reports that show partial antibacterial ingredients could result in side effects. Objectives The main objective is to test the antibacterial effect of water-soluble chitosan while the evaluation of the mouthwash appears as a secondary aim. Material and Methods The chitosan was obtained from the Application Chemistry Company (Taiwan). The authors investigated the antibacterial effects of water-soluble chitosan against oral bacteria at different temperatures (25-37ºC) and pH values (pH 5-8), and evaluated the antibacterial activities of a self-made water-soluble chitosan-containing mouthwash by in vitro and in vivo experiments, and analyzed the acute toxicity of the mouthwashes. The acute toxicity was analyzed with the pollen tube growth (PTG) test. The growth inhibition values against the logarithmic scale of the test concentrations produced a concentrationresponse curve. The IC50 value was calculated by interpolation from the data. Results The effect of the pH variation (5-8) on the antibacterial activity of water-soluble chitosan against tested oral bacteria was not significant. The maximal antibacterial activity of water-soluble chitosan occurred at 37ºC. The minimum bactericidal concentration (MBC) of water-soluble chitosan on Streptococcus mutans and Lactobacilli brevis were 400 µg/mL and 500 µg/mL, respectively. Only 5 s of contact between water-soluble chitosan and oral bacteria attained at least 99.60% antibacterial activity at a concentration of 500 µg/mL. The water-soluble chitosan-containin g mouthwash significantly demonstrated antibacterial activity that was similar to that of commercial mouthwashes (>99.91%) in both in vitro and in vivo experiments. In addition, the alcohol

  18. The effects of three different food acids on the attrition-corrosion wear of human dental enamel

    NASA Astrophysics Data System (ADS)

    Zhang, Yichi; Arsecularatne, Joseph A.; Hoffman, Mark

    2015-07-01

    With increased consumption of acidic drinks and foods, the wear of human teeth due to attrition in acidic environments is an increasingly important issue. Accordingly, the present paper investigates in vitro the wear of human enamel in three different acidic environments. Reciprocating wear tests in which an enamel cusp slides on an enamel flat surface were carried out using acetic, citric and lactic acid lubricants (at pH 3-3.5). Distilled water was also included as a lubricant for comparison. Focused ion beam milling and scanning electron microscopy imaging were then used to investigate the enamel subsurfaces following wear tests. Nanoindentation was used to ascertain the changes in enamel mechanical properties. The study reveals crack generation along the rod boundaries due to the exposure of enamel to the acidic environments. The wear mechanism changes from brittle fracture in distilled water to ploughing or shaving of the softened layer in acidic environments, generating a smooth surface with the progression of wear. Moreover, nanoindentation results of enamel samples which were exposed to the above acids up to a duration of the wear tests show decreasing hardness and Young’s modulus with exposure time.

  19. Application of the specular and diffuse reflection analysis for in vitro diagnostics of dental erosion: correlation with enamel softening, roughness, and calcium release

    PubMed Central

    Rakhmatullina, Ekaterina; Bossen, Anke; Höschele, Christoph; Wang, Xiaojie; Beyeler, Barbara; Meier, Christoph; Lussi, Adrian

    2011-01-01

    We present assembly and application of an optical reflectometer for the analysis of dental erosion. The erosive procedure involved acid-induced softening and initial substance loss phases, which are considered to be difficult for visual diagnosis in a clinic. Change of the specular reflection signal showed the highest sensitivity for the detection of the early softening phase of erosion among tested methods. The exponential decrease of the specular reflection intensity with erosive duration was compared to the increase of enamel roughness. Surface roughness was measured by optical analysis, and the observed tendency was correlated with scanning electron microscopy images of eroded enamel. A high correlation between specular reflection intensity and measurement of enamel softening (r2 ≥ −0.86) as well as calcium release (r2 ≥ −0.86) was found during erosion progression. Measurement of diffuse reflection revealed higher tooth-to-tooth deviation in contrast to the analysis of specular reflection intensity and lower correlation with other applied methods (r2 = 0.42–0.48). The proposed optical method allows simple and fast surface analysis and could be used for further optimization and construction of the first noncontact and cost-effective diagnostic tool for early erosion assessment in vivo. PMID:22029364

  20. Application of the specular and diffuse reflection analysis for in vitro diagnostics of dental erosion: correlation with enamel softening, roughness, and calcium release.

    PubMed

    Rakhmatullina, Ekaterina; Bossen, Anke; Höschele, Christoph; Wang, Xiaojie; Beyeler, Barbara; Meier, Christoph; Lussi, Adrian

    2011-10-01

    We present assembly and application of an optical reflectometer for the analysis of dental erosion. The erosive procedure involved acid-induced softening and initial substance loss phases, which are considered to be difficult for visual diagnosis in a clinic. Change of the specular reflection signal showed the highest sensitivity for the detection of the early softening phase of erosion among tested methods. The exponential decrease of the specular reflection intensity with erosive duration was compared to the increase of enamel roughness. Surface roughness was measured by optical analysis, and the observed tendency was correlated with scanning electron microscopy images of eroded enamel. A high correlation between specular reflection intensity and measurement of enamel softening (r(2) ≥ -0.86) as well as calcium release (r(2) ≥ -0.86) was found during erosion progression. Measurement of diffuse reflection revealed higher tooth-to-tooth deviation in contrast to the analysis of specular reflection intensity and lower correlation with other applied methods (r(2) = 0.42-0.48). The proposed optical method allows simple and fast surface analysis and could be used for further optimization and construction of the first noncontact and cost-effective diagnostic tool for early erosion assessment in vivo. PMID:22029364

  1. Application of the specular and diffuse reflection analysis for in vitro diagnostics of dental erosion: correlation with enamel softening, roughness, and calcium release

    NASA Astrophysics Data System (ADS)

    Rakhmatullina, Ekaterina; Bossen, Anke; Höschele, Christoph; Wang, Xiaojie; Beyeler, Barbara; Meier, Christoph; Lussi, Adrian

    2011-10-01

    We present assembly and application of an optical reflectometer for the analysis of dental erosion. The erosive procedure involved acid-induced softening and initial substance loss phases, which are considered to be difficult for visual diagnosis in a clinic. Change of the specular reflection signal showed the highest sensitivity for the detection of the early softening phase of erosion among tested methods. The exponential decrease of the specular reflection intensity with erosive duration was compared to the increase of enamel roughness. Surface roughness was measured by optical analysis, and the observed tendency was correlated with scanning electron microscopy images of eroded enamel. A high correlation between specular reflection intensity and measurement of enamel softening (r2 >= -0.86) as well as calcium release (r2 >= -0.86) was found during erosion progression. Measurement of diffuse reflection revealed higher tooth-to-tooth deviation in contrast to the analysis of specular reflection intensity and lower correlation with other applied methods (r2 = 0.42-0.48). The proposed optical method allows simple and fast surface analysis and could be used for further optimization and construction of the first noncontact and cost-effective diagnostic tool for early erosion assessment in vivo.

  2. Preparation of fluoride substituted apatite cements as the building blocks for tooth enamel restoration

    NASA Astrophysics Data System (ADS)

    Wei, Jie; Wang, Jiecheng; Liu, Xiaochen; Ma, Jian; Liu, Changsheng; Fang, Jing; Wei, Shicheng

    2011-06-01

    Fluoride substituted apatite cement (fs-AC) was synthesized by using the cement powders of tetracalcium phosphate (TTCP) and sodium fluoride (NaF), and the cement powders were mixed with diluted phosphoric acid (H 3PO 4) as cement liquid to form fs-AC paste. The fs-AC paste could be directly filled into the carious cavities to repair damaged dental enamel. The results indicated that the fs-AC paste was changed into fluorapatite crystals with the atom molar ratio for calcium to phosphorus of 1.66 and the F ion amount of 3 wt% after self-hardening for 2 days. The solubility of fs-AC in Tris-HCl solution (pH 6) was slightly lower than hydroxyapatite cement (HAC) that was similar to the apatite in enamel, indicating the fs-AC was much insensitive to the weakly acidic solution than the apatite in enamel. The fs-AC was tightly combined with the enamel surface because of the chemical reaction between the fs-AC and the apatite in enamel after the caries cavities was filled with fs-AC. The extracts of fs-AC caused no cytotoxicity on L929 cells, which satisfied the relevant criterion on dental biomaterials, revealing good cytocompatibility. The fs-AC had potential prospect for the reconstitution of carious lesion of dental enamel.

  3. The possible correlation between dental enamel hypoplasia and a historic natural disaster in the Roman population of Herculaneum (79 AD - central Italy).

    PubMed

    D'Anastasio, R; Cesana, D T; Viciano, J; Sciubba, M; Nibaruta, P; Capasso, L

    2013-01-01

    Dental enamel hypoplasia is usually read as a sign of a systematic growth disturbance during childhood. Following the analysis of human teeth from Herculaneum (79 AD, Central Italy), the authors focused on linear enamel hypoplasia (LEH) manifestations in order to delineate a possible correlation between their frequency and distribution and the earthquake that occurred in 62 AD, which is well documented in historical literature. The human remains from Herculaneum were buried at the same time as the Vesuvius eruption and represent an exceptional snapshot of life in the Roman Imperial Age. The Goodman and Rose method (1990) was used for attributing an "age at the moment of stress" for every skeleton in order to delineate the epidemiology of the enamel hypoplasia. When LEH frequency was analysed by age, two different age groups showed relevant patterns of hypoplasia: the first peak was evident in individuals between 14 and 20 years who were younger than 6 years at the time of the 62 AD earthquake, and a second peak was noted in adults of 30 +/- 5 years old, which suggests the presence of another stressful event that occurred 10 years before the earthquake, around 53 AD. The bimodal distribution of enamel hypoplasia could be the consequence of two different historical periods characterized by instability in the food supply, unhygienic conditions, and epidemic episodes; our data suggest that the first peak could be related to a decline in health status as an effect of the 62 AD earthquake. The relationship between recent natural disasters and variations in health status in modern populations is well documented in scientific literature. Our research represents the first attempt to correlate the status of health to an earthquake of known date in an archaeological population. PMID:24620565

  4. Using Dental Enamel Wrinkling to Define Sauropod Tooth Morphotypes from the Cañadón Asfalto Formation, Patagonia, Argentina

    PubMed Central

    Holwerda, Femke M.; Pol, Diego; Rauhut, Oliver W. M.

    2015-01-01

    The early Middle Jurassic is regarded as the period when sauropods diversified and became major components of the terrestrial ecosystems. Not many sites yield sauropod material of this time; however, both cranial and postcranial material of eusauropods have been found in the Cañadón Asfalto Formation (latest Early Jurassic–early Middle Jurassic) in Central Patagonia (Argentina), which may help to shed light on the early evolution of eusauropods. These eusauropod remains include teeth associated with cranial and mandibular material as well as isolated teeth found at different localities. In this study, an assemblage of sauropod teeth from the Cañadón Asfalto Formation found in four different localities in the area of Cerro Condor (Chubut, Argentina) is used as a mean of assessing sauropod species diversity at these sites. By using dental enamel wrinkling, primarily based on the shape and orientation of grooves and crests of this wrinkling, we define and describe three different morphotypes. With the exception of one taxon, for which no cranial material is currently known, these morphotypes match the local eusauropod diversity as assessed based on postcranial material. Morphotype I is tentatively assigned to Patagosaurus, whereas morphotypes II and III correspond to new taxa, which are also distinguished by associated postcranial material. This study thus shows that enamel wrinkling can be used as a tool in assessing sauropod diversity. PMID:25692466

  5. Using dental enamel wrinkling to define sauropod tooth morphotypes from the Cañadón Asfalto Formation, Patagonia, Argentina.

    PubMed

    Holwerda, Femke M; Pol, Diego; Rauhut, Oliver W M

    2015-01-01

    The early Middle Jurassic is regarded as the period when sauropods diversified and became major components of the terrestrial ecosystems. Not many sites yield sauropod material of this time; however, both cranial and postcranial material of eusauropods have been found in the Cañadón Asfalto Formation (latest Early Jurassic-early Middle Jurassic) in Central Patagonia (Argentina), which may help to shed light on the early evolution of eusauropods. These eusauropod remains include teeth associated with cranial and mandibular material as well as isolated teeth found at different localities. In this study, an assemblage of sauropod teeth from the Cañadón Asfalto Formation found in four different localities in the area of Cerro Condor (Chubut, Argentina) is used as a mean of assessing sauropod species diversity at these sites. By using dental enamel wrinkling, primarily based on the shape and orientation of grooves and crests of this wrinkling, we define and describe three different morphotypes. With the exception of one taxon, for which no cranial material is currently known, these morphotypes match the local eusauropod diversity as assessed based on postcranial material. Morphotype I is tentatively assigned to Patagosaurus, whereas morphotypes II and III correspond to new taxa, which are also distinguished by associated postcranial material. This study thus shows that enamel wrinkling can be used as a tool in assessing sauropod diversity. PMID:25692466

  6. Erosive potential of commonly used beverages, medicated syrup, and their effects on dental enamel with and without restoration: An in vitro study

    PubMed Central

    Trivedi, Krishna; Bhaskar, Vijay; Ganesh, Mahadevan; Venkataraghavan, Karthik; Choudhary, Prashant; Shah, Shalin; Krishnan, Ramesh

    2015-01-01

    Aim: This study evaluates erosive potential of commonly used beverages, medicated syrup, and their effects on dental enamel with and without restoration in vitro. Materials and Methods: Test medias used in this study included carbonated beverage, noncarbonated beverage, high-energy sports drink medicated cough syrup, distilled water as the control. A total of 110 previously extracted human premolar teeth were selected for the study. Teeth were randomly divided into two groups. Test specimens were randomly distributed to five beverages groups and comprised 12 specimens per group. Surface roughness (profilometer) readings were performed at baseline and again, following immersion for 14 days (24 h/day). Microleakage was evaluated. The results obtained were analyzed for statistical significance using SPSS-PC package using the multiple factor ANOVA at a significance level of P < 0.05. Paired t-test, Friedman test ranks, and Wilcoxon signed ranks test. Results: For surface roughness high-energy sports drink and noncarbonated beverage showed the highly significant difference with P values of 0.000 and 0.000, respectively compared to other test media. For microleakage high-energy sports drink had significant difference in comparison to noncarbonated beverage (P = 0.002), medicated syrup (P = 0.000), and distilled water (P = 0.000). Conclusion: High-energy sports drink showed highest surface roughness value and microleakage score among all test media and thus greater erosive potential to enamel while medicated syrup showed least surface roughness value and microleakage among all test media. PMID:26538901

  7. The developmental clock of dental enamel: a test for the periodicity of prism cross-striations in modern humans and an evaluation of the most likely sources of error in histological studies of this kind

    PubMed Central

    Antoine, Daniel; Hillson, Simon; Dean, M Christopher

    2009-01-01

    Dental tissues contain regular microscopic structures believed to result from periodic variations in the secretion of matrix by enamel- and dentine-forming cells. Counts of these structures are an important tool for reconstructing the chronology of dental development in both modern and fossil hominids. Most studies rely on the periodicity of the regular cross-banding that occurs along the long axis of enamel prisms. These prism cross-striations are widely thought to reflect a circadian rhythm of enamel matrix secretion and are generally regarded as representing daily increments of tissue. Previously, some researchers have argued against the circadian periodicity of these structures and questioned their use in reconstructing dental development. Here we tested the periodicity of enamel cross-striations – and the accuracy to which they can be used – in the developing permanent dentition of five children, excavated from a 19th century crypt in London, whose age-at-death was independently known. The interruption of crown formation by death was used to calibrate cross-striation counts. All five individuals produced counts that were strongly consistent with those expected from the independently known ages, taking into account the position of the neonatal line and factors of preservation. These results confirm that cross-striations do indeed reflect a circadian rhythm in enamel matrix secretion. They further validate their use in reconstructing dental development and in determining the age-at-death of the remains of children whose dentitions are still forming at the time of death. Significantly they identify the most likely source of error and the common difficulties encountered in histological studies of this kind. PMID:19166472

  8. Abalone water-soluble matrix for self-healing biomineralization of tooth defects.

    PubMed

    Wen, Zhenliang; Chen, Jingdi; Wang, Hailiang; Zhong, Shengnan; Hu, Yimin; Wang, Zhili; Zhang, Qiqing

    2016-10-01

    Enamel cannot heal by itself if damaged. Hydroxyapatite (HAP) is main component of human enamel. Formation of enamel-like materials for healing enamel defects remains a challenge. In this paper, we successfully isolated the abalone water-soluble matrix (AWSM) with 1.53wt% the abalone water-soluble protein (AWSPro) and 2.04wt% the abalone water-soluble polysaccharide (AWSPs) from abandoned abalone shell, and self-healing biomineralization of tooth defects was successfully achieved in vitro. Based on X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), hot field emission scanning electron microscopy (HFESEM) and energy dispersive spectrometer (EDS) analysis, the results showed that the AWSM can efficiently induce remineralization of HAP. The enamel-like HAP was successfully achieved onto etched enamel's surface due to the presence of the AWSM. Moreover, the remineralized effect of eroded enamel was growing with the increase of the AWSM. This study provides a solution to the resource waste and environmental pollution caused by abandoned abalone shell, and we provides a new method for self-healing remineralization of enamel defects by AWSM and develops a novel dental material for potential clinical dentistry application. PMID:27287112

  9. Enamel proteins mitigate mechanical and structural degradations in mature human enamel during acid attack

    NASA Astrophysics Data System (ADS)

    Lubarsky, Gennady V.; Lemoine, Patrick; Meenan, Brian J.; Deb, Sanjukta; Mutreja, Isha; Carolan, Patrick; Petkov, Nikolay

    2014-04-01

    A hydrazine deproteination process was used to investigate the role of enamel proteins in the acid erosion of mature human dental enamel. Bright field high resolution transmission electron micrographs and x-ray diffraction analysis show no crystallographic changes after the hydrazine treatment with similar nanoscale hydroxyapatite crystallite size and orientation for sound and de-proteinated enamel. However, the presence of enamel proteins reduces the erosion depth, the loss of hardness and the loss of structural order in enamel, following exposure to citric acid. Nanoindentation creep is larger for sound enamel than for deproteinated enamel but it reduces in sound enamel after acid attack. These novel results are consistent with calcium ion-mediated visco-elasticty in enamel matrix proteins as described previously for nacre, bone and dental proteins. They are also in good agreement with a previous double layer force spectroscopy study by the authors which found that the proteins electrochemically buffer enamel against acid attack. Finally, this suggests that acid attack, and more specifically dental erosion, is influenced by ionic permeation through the enamel layer and that it is mitigated by the enamel protein matrix.

  10. Absorption and thermal study of dental enamel when irradiated with Nd:YAG laser with the aim of caries prevention

    NASA Astrophysics Data System (ADS)

    Boari, H. G. D.; Ana, P. A.; Eduardo, C. P.; Powell, G. L.; Zezell, D. M.

    2009-07-01

    It is widely recognized that Nd:YAG can increase enamel resistance to demineralization; however, the safe parameters and conditions that enable the application of Nd:YAG laser irradiation in vivo are still unknown. The aim of this study was to determine a dye as a photoabsorber for Nd:YAG laser and to verify in vitro a safe condition of Nd:YAG irradiation for caries prevention. Fifty-eight human teeth were selected. In a first morphological study, four dyes (waterproof India ink., iron oxide, caries indicator and coal paste) were tested before Nd:YAG laser irradiation, under two different irradiation conditions: 60 mJ/pulse and 10 Hz (84.9 J/cm2); 80 mJ/pulse and 10 Hz (113.1 J/cm2). In a second study, the enamel surface and pulp chamber temperatures were evaluated during laser irradiations. All dyes produced enamel surface melting, with the exception of the caries indicator, and coal paste was the only dye that could be completely removed. All irradiation conditions produced temperature increases of up to 615.08°C on the enamel surface. Nd:YAG laser irradiation at 60 mJ/pulse, 10 Hz and 84.9 J/cm2 promoted no harmful temperature increase in the pulp chamber (ANOVA, p < 0.05). Among all dyes tested, the coal paste was an efficient photoabsorber for Nd:YAG irradiation, considered feasible for clinical practice. Nd:YAG laser at 84.9 J/cm2 can be indicated as a safe parameter for use in caries prevention.

  11. Morphological and Structural Changes on Human Dental Enamel After Er:YAG Laser Irradiation: AFM, SEM, and EDS Evaluation

    PubMed Central

    Rodríguez-Vilchis, Laura Emma; Olea-Mejìa, Oscar Fernando; Sánchez-Flores, Ignacio; Centeno-Pedraza, Claudia

    2011-01-01

    Abstract Objective: The purpose of this study was to evaluate, using atomic force microscopy (AFM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), the morphological and structural changes of the enamel after irradiation with the Er:YAG laser. Background data: A previous study showed that subablative Er:YAG laser irradiation produced undesirable morphological changes on the enamel surface, such as craters and cracks; however, the enamel acid resistance was not increased. Methods: Fifty-two samples of human enamel were divided into four groups (n = 13): Group I was the control (no laser irradiation), whereas Groups II, III, and IV were irradiated with the Er:YAG 100 mJ (12.7 J/cm2), 100 mJ (7.5 J/cm2), and 150 mJ (11 J/cm2), respectively, at 10 Hz with water spray. The morphological changes were observed by AFM and SEM. The weight percentages (wt%) of calcium (Ca), phosphorus (P), oxygen (O) and chlorine (Cl) were determined in the resultant craters and their periphery using EDS. Kruskal–Wallis and Mann–Whitney U tests were performed (p ≤ 0.05) to distinguish significant differences among the groups. Results: The AFM images showed cracks with depths between 250 nm and 750 nm for Groups II and IV, respectively, and the widths of these cracks were 5.37 μm and 2.58 μm. The interior of the cracks showed a rough surface. The SEM micrographs revealed morphological changes. Significant differences were detected in Ca, P, and Cl in the crater and its periphery. Conclusions: AFM observations showed triangular-shaped cracks, whereas craters and cracks were evident by SEM in all irradiated samples. It was not possible to establish a characteristic chemical pattern in the craters. PMID:21417912

  12. Improvement of the skeletal and dental hypophosphatasia phenotype in Alpl−/− mice by administration of soluble (non-targeted) chimeric alkaline phosphatase

    PubMed Central

    Gasque, Kellen; Foster, Brian L.; Kuss, Pia; Yadav, Manisha C.; Liu, Jin; Kiffer-Moreira, Tina; van Elsas, Andrea; Hatch, Nan; Somerman, Martha J.; Millán, JoséLuis

    2014-01-01

    Hypophosphatasia (HPP) results from ALPL gene mutations, which lead to a deficiency of tissue-nonspecific alkaline phosphatase (TNAP), and accumulation of inorganic pyrophosphate, a potent inhibitor of mineralization that is also a natural substrate of TNAP, in the extracellular space. HPP causes mineralization disorders including soft bones (rickets or osteomalacia) and defects in teeth and periodontal tissues. Enzyme replacement therapy using mineral-targeting recombinant TNAP has proven effective in preventing skeletal and dental defects in TNAP knockout (Alpl−/−) mice, a model for life-threatening HPP. Here, we show that the administration of a soluble, intestinal-like chimeric alkaline phosphatase (ChimAP) improves the manifestations of HPP in Alpl−/− mice. Mice received daily subcutaneous injections of ChimAP at doses of 1, 8 or 16 mg/kg, from birth for up to 53 days. Lifespan and body weight of Alpl−/− mice were normalized, and vitamin B6-associated seizures were absent with 16 mg/kg/day of ChimAP. Radiographs, μCT and histological analyses documented improved mineralization in cortical and trabecular bone and secondary ossification centers in long bones of ChimAP16-treated mice. There was no evidence of craniosynostosis in the ChimAP16-treated mice and we did not detect ectopic calcification by radiography and histology in the aortas, stomachs, kidneys or lungs in any of the treatment groups. Molar tooth development and function improved with the highest ChimAP dose, including enamel, dentin, and tooth morphology. Cementum remained deficient and alveolar bone mineralization was reduced compared to controls, though ChimAP-treated Alpl−/− mice featured periodontal attachment and retained teeth. This study provides the first evidence for the pharmacological efficacy of ChimAP for use in the treatment of skeletal and dental manifestations of HPP. PMID:25433339

  13. Improvement of the skeletal and dental hypophosphatasia phenotype in Alpl-/- mice by administration of soluble (non-targeted) chimeric alkaline phosphatase.

    PubMed

    Gasque, Kellen C S; Foster, Brian L; Kuss, Pia; Yadav, Manisha C; Liu, Jin; Kiffer-Moreira, Tina; van Elsas, Andrea; Hatch, Nan; Somerman, Martha J; Millán, José Luis

    2015-03-01

    Hypophosphatasia (HPP) results from ALPL gene mutations, which lead to a deficiency of tissue-nonspecific alkaline phosphatase (TNAP), and accumulation of inorganic pyrophosphate, a potent inhibitor of mineralization that is also a natural substrate of TNAP, in the extracellular space. HPP causes mineralization disorders including soft bones (rickets or osteomalacia) and defects in teeth and periodontal tissues. Enzyme replacement therapy using mineral-targeting recombinant TNAP has proven effective in preventing skeletal and dental defects in TNAP knockout (Alpl(-/-)) mice, a model for life-threatening HPP. Here, we show that the administration of a soluble, intestinal-like chimeric alkaline phosphatase (ChimAP) improves the manifestations of HPP in Alpl(-/-) mice. Mice received daily subcutaneous injections of ChimAP at doses of 1, 8 or 16 mg/kg, from birth for up to 53 days. Lifespan and body weight of Alpl(-/-) mice were normalized, and vitamin B6-associated seizures were absent with 16 mg/kg/day of ChimAP. Radiographs, μCT and histological analyses documented improved mineralization in cortical and trabecular bone and secondary ossification centers in long bones of ChimAP16-treated mice. There was no evidence of craniosynostosis in the ChimAP16-treated mice and we did not detect ectopic calcification by radiography and histology in the aortas, stomachs, kidneys or lungs in any of the treatment groups. Molar tooth development and function improved with the highest ChimAP dose, including enamel, dentin, and tooth morphology. Cementum remained deficient and alveolar bone mineralization was reduced compared to controls, though ChimAP-treated Alpl(-/-) mice featured periodontal attachment and retained teeth. This study provides the first evidence for the pharmacological efficacy of ChimAP for use in the treatment of skeletal and dental manifestations of HPP. PMID:25433339

  14. An investigation using atomic force microscopy nanoindentation of dental enamel demineralization as a function of undissociated acid concentration and differential buffer capacity

    NASA Astrophysics Data System (ADS)

    Barbour, Michele E.; Shellis, R. Peter

    2007-02-01

    Acidic drinks and foodstuffs can demineralize dental hard tissues, leading to a pathological condition known as dental erosion, which is of increasing clinical concern. The first step in enamel dissolution is a demineralization of the outer few micrometres of tissue, which results in a softening of the structure. The primary determinant of dissolution rate is pH, but the concentration of undissociated acid, which is related to buffer capacity, also appears to be important. In this study, atomic force microscopy nanoindentation was used to measure the first initial demineralization (softening) induced within 1 min by exposure to solutions with a range of undissociated acid concentration and natural pH of 3.3 or with an undissociated acid concentration of 10 mmol l-1 and pH adjusted to 3.3. The results indicate that differential buffering capacity is a better determinant of softening than undissociated acid concentration. Under the conditions of these experiments, a buffer capacity of >3 mmol l-1 pH-1 does not have any further effect on dissolution rate. These results imply that differential buffering capacity should be used for preference over undissociated acid concentration or titratable acidity, which are more commonly employed in the literature.

  15. To What Extent is Primate Second Molar Enamel Occlusal Morphology Shaped by the Enamel-Dentine Junction?

    PubMed Central

    Gilissen, Emmanuel; Thiery, Ghislain

    2015-01-01

    The form of two hard tissues of the mammalian tooth, dentine and enamel, is the result of a combination of the phylogenetic inheritance of dental traits and the adaptive selection of these traits during evolution. Recent decades have been significant in unveiling developmental processes controlling tooth morphogenesis, dental variation and the origination of dental novelties. The enamel-dentine junction constitutes a precursor for the morphology of the outer enamel surface through growth of the enamel cap which may go along with the addition of original features. The relative contribution of these two tooth components to morphological variation and their respective response to natural selection is a major issue in paleoanthropology. This study will determine how much enamel morphology relies on the form of the enamel-dentine junction. The outer occlusal enamel surface and the enamel-dentine junction surface of 76 primate second upper molars are represented by polygonal meshes and investigated using tridimensional topometrical analysis. Quantitative criteria (elevation, inclination, orientation, curvature and occlusal patch count) are introduced to show that the enamel-dentine junction significantly constrains the topographical properties of the outer enamel surface. Our results show a significant correlation for elevation, orientation, inclination, curvature and occlusal complexity between the outer enamel surface and the enamel dentine junction for all studied primate taxa with the exception of four modern humans for curvature (p<0.05). Moreover, we show that, for all selected topometrical parameters apart from occlusal patch count, the recorded correlations significantly decrease along with enamel thickening in our sample. While preserving tooth integrity by providing resistance to wear and fractures, the variation of enamel thickness may modify the curvature present at the occlusal enamel surface in relation to enamel-dentine junction, potentially modifying

  16. Influence of an oxygen-inhibited layer on enamel bonding of dental adhesive systems: surface free-energy perspectives.

    PubMed

    Ueta, Hirofumi; Tsujimoto, Akimasa; Barkmeier, Wayne W; Oouchi, Hajime; Sai, Keiichi; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

    2016-02-01

    The influence of an oxygen-inhibited layer (OIL) on the shear bond strength (SBS) to enamel and surface free-energy (SFE) of adhesive systems was investigated. The adhesive systems tested were Scotchbond Multipurpose (SM), Clearfil SE Bond (CS), and Scotchbond Universal (SU). Resin composite was bonded to bovine enamel surfaces to determine the SBS, with and without an OIL, of adhesives. The SFE of cured adhesives with and without an OIL were determined by measuring the contact angles of three test liquids. There were no significant differences in the mean SBS of SM and CS specimens with or without an OIL; however, the mean SBS of SU specimens with an OIL was significantly higher than that of SU specimens without an OIL. For all three systems, the mean total SFE (γS), polarity force (γSp), and hydrogen bonding force (γSh) values of cured adhesives with an OIL were significantly higher than those of cured adhesives without an OIL. The results of this study indicate that the presence of an OIL promotes higher SBS of a single-step self-etch adhesive system, but not of a three-step or a two-step self-etch primer system. The SFE values of cured adhesives with an OIL were significantly higher than those without an OIL. The SFE characteristics of the OIL of adhesives differed depending on the type of adhesive. PMID:26647775

  17. Analysis of Dental Enamel Surface Submitted to Fruit Juice Plus Soymilk by Micro X-Ray Fluorescence: In Vitro Study.

    PubMed

    Salmos Brito, Janaína; Santos Neto, Alexandrino; Silva, Luciano; Menezes, Rebeca; Araújo, Natália; Carneiro, Vanda; Moreno, Lara Magalhães; Miranda, Jéssica; Álvares, Pâmella; Nevares, Giselle; Xavier, Felipe; Arruda, José Alcides; Bessa-Nogueira, Ricardo; Santos, Natanael; Queiroz, Gabriela; Sobral, Ana Paula; Silveira, Márcia; Albuquerque, Diana; Gerbi, Marleny

    2016-01-01

    Objective. This paper aimed to analyze the in vitro industrialized fruit juices effect plus soy to establish the erosive potential of these solutions. Materials and Methods. Seventy bovine incisors were selected after being evaluated under stereomicroscope. Their crowns were prepared and randomly divided into 7 groups, using microhardness with allocation criteria. The crowns were submitted to the fruit juice plus soy during 15 days, twice a day. The pH values, acid titration, and Knoop microhardness were recorded and the specimens were evaluated using X-ray microfluorescence (µXRF). Results. The pH average for all juices and after 3 days was significantly below the critical value for dental erosion. In average, the pH value decreases 14% comparing initial time and pH after 3 days. Comparing before and after, there was a 49% microhardness decrease measured in groups (p < 0.05). Groups G1, G2, G5, and G6 are above this average. The analysis by μXRF showed a decrease of approximately 7% Ca and 4% P on bovine crowns surface. Florida (FL) statistical analysis showed a statistically significant 1 difference between groups. Thus, a tooth chance to suffer demineralization due to industrialized fruit juices plus soy is real. PMID:26977451

  18. Analysis of Dental Enamel Surface Submitted to Fruit Juice Plus Soymilk by Micro X-Ray Fluorescence: In Vitro Study

    PubMed Central

    Salmos Brito, Janaína; Santos Neto, Alexandrino; Silva, Luciano; Menezes, Rebeca; Araújo, Natália; Carneiro, Vanda; Moreno, Lara Magalhães; Miranda, Jéssica; Álvares, Pâmella; Nevares, Giselle; Xavier, Felipe; Arruda, José Alcides; Bessa-Nogueira, Ricardo; Santos, Natanael; Queiroz, Gabriela; Sobral, Ana Paula; Silveira, Márcia; Albuquerque, Diana; Gerbi, Marleny

    2016-01-01

    Objective. This paper aimed to analyze the in vitro industrialized fruit juices effect plus soy to establish the erosive potential of these solutions. Materials and Methods. Seventy bovine incisors were selected after being evaluated under stereomicroscope. Their crowns were prepared and randomly divided into 7 groups, using microhardness with allocation criteria. The crowns were submitted to the fruit juice plus soy during 15 days, twice a day. The pH values, acid titration, and Knoop microhardness were recorded and the specimens were evaluated using X-ray microfluorescence (µXRF). Results. The pH average for all juices and after 3 days was significantly below the critical value for dental erosion. In average, the pH value decreases 14% comparing initial time and pH after 3 days. Comparing before and after, there was a 49% microhardness decrease measured in groups (p < 0.05). Groups G1, G2, G5, and G6 are above this average. The analysis by μXRF showed a decrease of approximately 7% Ca and 4% P on bovine crowns surface. Florida (FL) statistical analysis showed a statistically significant 1 difference between groups. Thus, a tooth chance to suffer demineralization due to industrialized fruit juices plus soy is real. PMID:26977451

  19. Sensitization Potential of Dental Resins: 2-Hydroxyethyl Methacrylate and Its Water-Soluble Oligomers Have Immunostimulatory Effects

    PubMed Central

    Fukumoto, Izumi; Tamura, Atsushi; Matsumura, Mitsuaki; Miura, Hiroyuki; Yui, Nobuhiko

    2013-01-01

    The immunostimulatory effects of the representative dental resin monomer 2-hydroxyethyl methacrylate (HEMA), a HEMA derivative that does not contain a double bond (2-hydroxyethyl isobutyrate, HEIB), and polymerized water-soluble oligomers of HEMA (PHEMA) were investigated. It is known that expression levels of either or both of CD54 and CD86 in THP-1 cells are increased by exposure to sensitizing substances. In this study, the expression levels of CD54 and CD86, the production of reactive oxygen species (ROS), and the viability of the cells were measured after 24 h of incubation with these materials at different concentrations. The concentrations of the materials that induced the expression of both CD54 and CD86 were low in the following order: NiSO4, HEMA, and methyl methacrylate (MMA). These results indicate that these dental resin monomers have lower sensitizing potentials than NiSO4. Although HEIB, which lacks a double bond, resulted in negligible ROS production and reduced cytotoxicity than HEMA, it induced the expression of CD54 and CD86. Comparison of the results for HEMA and HEIB indicates that dental resin monomer-induced sensitization may be related not only to the oxidative stress related to the methacryloyl group but also to the structures of these compounds. Of particular interest is the result that a water-soluble PHEMA oligomer with a relatively high-molecular weight also exhibited negligible cytotoxicity, whereas the expression level of CD54 increased after exposure to PHEMA at a high concentration. This result serves as a warning that polymerized substances also have the potential to induce sensitization. This study provides insight into the nature of allergic responses to dental resin materials in clinical use and may facilitate the development of more biocompatible restorative materials in the future. PMID:24312427

  20. Scanning Electron Microscope Characterization of Erosive Enamel in Human Teeth.

    PubMed

    Worawongvasu, Ratthapong

    2015-01-01

    This study aimed to examine the surface characteristics of erosive enamel in extracted human teeth by scanning electron microscopy. Morphologic changes in naturally eroded enamel depend on the stages of dental erosion. In its early stages, the enamel surfaces show a honeycomb appearance due to the dissolution of enamel rod ends. In its advanced stages, the erosive process involves the underlying dentin and the eroded dentin shows exposed dentinal tubules and the dentinal matrix may be exposed due to the dissolution of the peri- and intertubular dentin. Evidence of remineralization is seen at the early stage of natural dental erosion. PMID:26214120

  1. Dental Calculus Arrest of Dental Caries

    PubMed Central

    Keyes, Paul H.; Rams, Thomas E.

    2016-01-01

    Background An inverse relationship between dental calculus mineralization and dental caries demineralization on teeth has been noted in some studies. Dental calculus may even form superficial layers over existing dental caries and arrest their progression, but this phenomenon has been only rarely documented and infrequently considered in the field of Cariology. To further assess the occurrence of dental calculus arrest of dental caries, this study evaluated a large number of extracted human teeth for the presence and location of dental caries, dental calculus, and dental plaque biofilms. Materials and methods A total of 1,200 teeth were preserved in 10% buffered formal saline, and viewed while moist by a single experienced examiner using a research stereomicroscope at 15-25× magnification. Representative teeth were sectioned and photographed, and their dental plaque biofilms subjected to gram-stain examination with light microscopy at 100× magnification. Results Dental calculus was observed on 1,140 (95%) of the extracted human teeth, and no dental carious lesions were found underlying dental calculus-covered surfaces on 1,139 of these teeth. However, dental calculus arrest of dental caries was found on one (0.54%) of 187 evaluated teeth that presented with unrestored proximal enamel caries. On the distal surface of a maxillary premolar tooth, dental calculus mineralization filled the outer surface cavitation of an incipient dental caries lesion. The dental calculus-covered carious lesion extended only slightly into enamel, and exhibited a brown pigmentation characteristic of inactive or arrested dental caries. In contrast, the tooth's mesial surface, without a superficial layer of dental calculus, had a large carious lesion going through enamel and deep into dentin. Conclusions These observations further document the potential protective effects of dental calculus mineralization against dental caries.

  2. Effect of immersion in various media on the sorption, solubility, elution of unreacted monomers, and flexural properties of two model dental composite compositions.

    PubMed

    Zhang, Yujie; Xu, Jingwei

    2008-06-01

    Immersion in various media has different effect on the properties of dental composites, such as sorption, solubility, elution of unreacted monomers, flexural strength, and flexural elastic modulus. In the present work, the effect of immersion in various media and the relationship between the variation of these properties and the components of dental composite were investigated. Two model dental composites were immersed in three different media-distilled water, artificial saliva, and ethanol/water, respectively, for a certain time. Their sorption, solubility, flexural strength, and flexural elastic modulus were tested according to the international standard. Elution of unreacted monomers was analyzed by using high performance liquid chromatography (HPLC) and the surface morphology of samples after immersion was observed using scanning electron microscope (SEM). The results showed that the effect on properties depended on the immersion media where ethanol/water had the most significant effect and these properties were related to the components of dental composite. PMID:18253815

  3. Alterations in enamel remineralization in vitro induced by blue light

    NASA Astrophysics Data System (ADS)

    Kato, I. T.; Zezell, D. M.; Mendes, F. M.; Wetter, N. U.

    2010-06-01

    Blue light, especially from LED devices, is a very frequently used tool in dental procedures. However, the investigations of its effects on dental enamel are focused primarily on enamel demineralization and fluoride retention. Despite the fact that this spectral region can inhibit enamel demineralization, the effects of the irradiation on demineralized enamel are not known. For this reason, we evaluated the effects of blue LED on remineralization of dental enamel. Artificial lesions were formed in bovine dental enamel blocks by immersing the samples in undersaturated acetate buffer. The lesions were irradiated with blue LED (455 nm, 1.38 W/cm2, 13.75 J/cm2, and 10 s) and remineralization was induced by pH-cycling process. Cross-sectional hardness was used to asses mineral changes after remineralization. Non-irradiated enamel lesions presented higher mineral content than irradiated ones. Furthermore, the mineral content of irradiated group was not significantly different from the lesion samples that were not submitted to the remineralization process. Results obtained in the present study show that the blue light is not innocuous for the dental enamel and inhibition of its remineralization can occur.

  4. Effect of hydroxyapatite whisker surface graft polymerization on water sorption, solubility and bioactivity of the dental resin composite.

    PubMed

    Liu, Fengwei; Jiang, Xiaoze; Bao, Shuang; Wang, Ruili; Sun, Bin; Zhu, Meifang

    2015-08-01

    The aim of this study was to investigate the effect of poly bisphenol A glycidyl methacrylate (poly(Bis-GMA)) grafted hydroxyapatite whisker (PGHW) on water sorption, solubility and bioactivity of the dental resin composite. PGHW with different graft ratios was synthesized, by controlling grafting time, and filled into a dental resin matrix respectively. Fracture surface of the resin composites showed that PGHW-matrix interfacial compatibility and bonding were enhanced, and lower amounts of poly(Bis-GMA) on PGHW-1h (graft ratio: 8.5 wt.%) could facilitate the dispersion of PGHW-1 h in the composite. The PGHW-1h filled resin composite absorbed the lowest amount of water (27.16 μg/mm(3), 7 d), whereas the untreated hydroxyapatite whisker (HW) filled resin composite absorbed the highest. PGHW with higher graft ratios induced the decrease of the monomer conversion in the resulting composite, therefore, the PGHW-18 h (graft ratio: 32.8 wt.%) filled resin composite had the highest solubility. In vitro bioactivity of the studied resin composites in simulated body fluid (SBF) showed that a dense and continuous apatite layer was formed on the surface of the resin composite, and the surface graft polymerization on the whisker did not significantly affect the apatite forming ability of the resin composite. It was revealed that graft polymerization of an appropriate amount of Bis-GMA onto HW could be an effective method to improve the interfacial properties and stability in water of the dental resin composite without compromising the bioactivity. PMID:26042702

  5. The influence of dental alloys on three-body wear of human enamel and dentin in an inlay-like situation.

    PubMed

    Graf, K; Johnson, G H; Mehl, A; Rammelsberg, P

    2002-01-01

    This in vitro study evaluated the effect of metal alloys on three-body wear resistance of enamel and dentin, and vice versa. Three-body wear of human enamel, dentin, a soft gold alloy (BiOcclus Inlay), a CoCr alloy (Remanium 2000), a resin cement (Variolink II) and a zinc oxide phosphate cement (Harvard) was investigated using the ACTA-machine. Sample chambers of eight sample wheels were prepared with pure materials or combinations of human tooth substance, alloys and cement, simulating an inlay-like situation. After 100,000 and 200,000 cycles in a millet suspension with a spring force of 20 N, the amount of abraded material was profilometrically measured and evaluated by 3D surface data analysis. After 200,000 cycles, the materials demonstrated a mean loss of 0.41 microm for CoCr, 51 microm for gold, 57 microm for enamel, 164 microm for dentin, 79 microm for Variolink and 369 microm for Harvard. Using ANOVA and the Games-Howell-test, resin cement, enamel and gold were a subset not shown to differ, as was zinc phosphate cement and dentin. CoCr demonstrated the least wear and differed significantly from all materials. Enamel wear was significantly reduced in mixed chambers with CoCr, and gold after 200,000 cycles compared to enamel in pure chambers. In summary, a soft gold alloy can be recommended for inlays when considering three-body abrasion since the wear rate of the "soft" gold alloy corresponded to that of human enamel. PMID:11931136

  6. Effects of Pamidronate on Dental Enamel Formation Assessed by Light Microscopy, Energy-Dispersive X-Ray Analysis, Scanning Electron Microscopy, and Microhardness Testing.

    PubMed

    Soares, Ana P; do Espírito Santo, Renan F; Line, Sérgio R P; Pinto, Maria das G F; Santos, Pablo de M; Toralles, Maria Betania P; do Espírito Santo, Alexandre R

    2016-06-01

    The aim of the present work was to investigate birefringence and morphology of the secretory-stage enamel organic extracellular matrix (EOECM), and structural and mechanical properties of mature enamel of upper incisors from adult rats that had been treated with pamidronate disodium (0.5 mg/kg/week for 56 days), using transmitted polarizing and bright-field light microscopies (TPLM and BFLM), energy-dispersive X-ray (EDX) analysis, scanning electron microscopy (SEM) and microhardness testing. BFLM showed no morphological changes of the EOECM in pamidronate and control groups, but TPLM revealed a statistically significant reduction in optical retardation values of birefringence brightness of pamidronate-treated rats when compared with control animals (p0.05). The present study indicates that pamidronate can affect birefringence of the secretory-stage EOECM, which does not seem to be associated with significant changes in morphological and/or mechanical properties of mature enamel. PMID:27212049

  7. CO2 laser irradiation enhances CaF2 formation and inhibits lesion progression on demineralized dental enamel-in vitro study.

    PubMed

    Zancopé, Bruna R; Rodrigues, Lívia P; Parisotto, Thais M; Steiner-Oliveira, Carolina; Rodrigues, Lidiany K A; Nobre-Dos-Santos, Marinês

    2016-04-01

    This study evaluated if Carbon dioxide (CO2) (λ 10.6 μm) laser irradiation combined with acidulated phosphate fluoride gel application (APF gel) enhances "CaF2" uptake by demineralized enamel specimens (DES) and inhibits enamel lesion progression. Thus, two studies were conducted and DES were subjected to APF gel combined or not with CO2 laser irradiation (11.3 or 20.0 J/cm(2), 0.4 or 0.7 W) performed before, during, or after APF gel application. In study 1, 165 DES were allocated to 11 groups. Fluoride as "CaF2 like material" formed on enamel was determined in 100 DES (n = 10/group), and the surface morphologies of 50 specimens were evaluated by scanning electron microscopy (SEM) before and after "CaF2" extraction. In study 2, 165 DES (11 groups, n = 15), subjected to the same treatments as in study 1, were further subjected to a pH-cycling model to simulate a high cariogenic challenge. The progression of demineralization in DES was evaluated by cross-sectional microhardness and polarized light microscopy analyses. Laser at 11.3 J/cm(2) applied during APF gel application increased "CaF2" uptake on enamel surface. Laser irradiation and APF gel alone arrested the lesion progression compared with the control (p < 0.05). Areas of melting, fusion, and cracks were observed. CO2 laser irradiation, combined with a single APF application enhanced "CaF2" uptake on enamel surface and a synergistic effect was found. However, regarding the inhibition of caries lesion progression, no synergistic effect could be demonstrated. In conclusion, the results have shown that irradiation with specific laser parameters significantly enhanced CaF2 uptake by demineralized enamel and inhibited lesion progression. PMID:26873502

  8. Enamel Regeneration - Current Progress and Challenges

    PubMed Central

    Baswaraj; H.K, Navin; K.B, Prasanna

    2014-01-01

    Dental Enamel is the outermost covering of teeth. It is hardest mineralized tissue present in the human body. Enamel faces the challenge of maintaining its integrity in a constant demineralization and remineralization within the oral environment and it is vulnerable to wear, damage, and decay. It cannot regenerate itself, because it is formed by a layer of cells that are lost after the tooth eruption. Conventional treatment relies on synthetic materials to restore lost enamel that cannot mimic natural enamel. With advances in material science and understanding of basic principles of organic matrix mediated mineralization paves a way for formation of synthetic enamel. The knowledge of enamel formation and understanding of protein interactions and their gene products function along with the isolation of postnatal stem cells from various sources in the oral cavity, and the development of smart materials for cell and growth factor delivery, makes possibility for biological based enamel regeneration. This article will review the recent endeavor on biomimetic synthesis and cell based strategies for enamel regeneration. PMID:25386548

  9. Microabrasion in tooth enamel discoloration defects: three cases with long-term follow-ups

    PubMed Central

    SUNDFELD, Renato Herman; SUNDFELD-NETO, Daniel; MACHADO, Lucas Silveira; FRANCO, Laura Molinar; FAGUNDES, Ticiane Cestari; BRISO, André Luiz Fraga

    2014-01-01

    Superficial irregularities and certain intrinsic stains on the dental enamel surfaces can be resolved by enamel microabrasion, however, treatment for such defects need to be confined to the outermost regions of the enamel surface. Dental bleaching and resin-based composite repair are also often useful for certain situations for tooth color corrections. This article presented and discussed the indications and limitations of enamel microabrasion treatment. Three case reports treated by enamel microabrasion were also presented after 11, 20 and 23 years of follow-ups. PMID:25141208

  10. Human enamel thickness and ENAM polymorphism

    PubMed Central

    Daubert, Diane M; Kelley, Joanna L; Udod, Yuriy G; Habor, Carolina; Kleist, Chris G; Furman, Ilona K; Tikonov, Igor N; Swanson, Willie J; Roberts, Frank A

    2016-01-01

    The tooth enamel development gene, enamelin (ENAM), showed evidence of positive selection during a genome-wide scan of human and primate DNA for signs of adaptive evolution. The current study examined the hypothesis that a single-nucleotide polymorphism (SNP) C14625T (rs7671281) in the ENAM gene identified in the genome-wide scan is associated with a change in enamel phenotype. African Americans were selected as the target population, as they have been reported to have a target SNP frequency of approximately 50%, whereas non-Africans are predicted to have a 96% SNP frequency. Digital radiographs and DNA samples from 244 teeth in 133 subjects were analysed, and enamel thickness was assessed in relation to SNP status, controlling for age, sex, tooth number and crown length. Crown length was found to increase with molar number, and females were found to have thicker enamel. Teeth with larger crowns also had thicker enamel, and older subjects had thinner enamel. Linear regression and generalized estimating equations were used to investigate the relationship between enamel thickness of the mandibular molars and ENAM SNP status; enamel in subjects with the derived allele was significantly thinner (P=0.040) when the results were controlled for sex, age, tooth number and crown length. The derived allele demonstrated a recessive effect on the phenotype. The data indicate that thinner dental enamel is associated with the derived ENAM genotype. This is the first direct evidence of a dental gene implicated in human adaptive evolution as having a phenotypic effect on an oral structure. PMID:27357321

  11. Human enamel thickness and ENAM polymorphism.

    PubMed

    Daubert, Diane M; Kelley, Joanna L; Udod, Yuriy G; Habor, Carolina; Kleist, Chris G; Furman, Ilona K; Tikonov, Igor N; Swanson, Willie J; Roberts, Frank A

    2016-01-01

    The tooth enamel development gene, enamelin (ENAM), showed evidence of positive selection during a genome-wide scan of human and primate DNA for signs of adaptive evolution. The current study examined the hypothesis that a single-nucleotide polymorphism (SNP) C14625T (rs7671281) in the ENAM gene identified in the genome-wide scan is associated with a change in enamel phenotype. African Americans were selected as the target population, as they have been reported to have a target SNP frequency of approximately 50%, whereas non-Africans are predicted to have a 96% SNP frequency. Digital radiographs and DNA samples from 244 teeth in 133 subjects were analysed, and enamel thickness was assessed in relation to SNP status, controlling for age, sex, tooth number and crown length. Crown length was found to increase with molar number, and females were found to have thicker enamel. Teeth with larger crowns also had thicker enamel, and older subjects had thinner enamel. Linear regression and generalized estimating equations were used to investigate the relationship between enamel thickness of the mandibular molars and ENAM SNP status; enamel in subjects with the derived allele was significantly thinner (P=0.040) when the results were controlled for sex, age, tooth number and crown length. The derived allele demonstrated a recessive effect on the phenotype. The data indicate that thinner dental enamel is associated with the derived ENAM genotype. This is the first direct evidence of a dental gene implicated in human adaptive evolution as having a phenotypic effect on an oral structure. PMID:27357321

  12. An evaluation of different doses of soluble aspirin and aspirin tablets in postoperative dental pain.

    PubMed Central

    Holland, I S; Seymour, R A; Ward-Booth, R P; Ord, R A; Lim, K L; Hoare, R C

    1988-01-01

    1. The efficacy of three different single doses (600, 900 and 1200 mg of soluble aspirin and aspirin tablets) was determined in a randomized placebo-controlled parallel study in 140 patients (70 females) with postoperative pain after removal of impacted third molars. 2. Patients treated with soluble aspirin 600 mg, 900 mg, 1200 mg and aspirin tablet 1200 mg reported significantly less pain (P less than 0.01) throughout the investigation period than those treated with placebo. 3. Overall pain scores after treatment with aspirin tablets 600 and 900 mg did not differ significantly from those after treatment with placebo (P greater than 0.05). 4. On a comparative dose basis, soluble aspirin was significantly more potent (P less than 0.05) than aspirin tablets. PMID:3190996

  13. To Analyse the Erosive Potential of Commercially Available Drinks on Dental Enamel and Various Tooth Coloured Restorative Materials – An In-vitro Study

    PubMed Central

    Jindal, Ritu; Mahajan, Sandeep; Sandhu, Sanam; Sharma, Sunila; Kaur, Rajwinder

    2016-01-01

    Introduction With the enormous change in life style pattern of a common man through the past few decades, there has been proportional variation in the amount and frequency of consumption of drinks. An increased consumption of these drinks will concurrently increase enamel surface roughness by demineralization, resulting in hypersensitivity and elevated caries risk. Aim The present study was designed to evaluate the erosive potential of commercially available drinks on tooth enamel and various tooth coloured restorative materials. Materials and Methods Extracted human teeth were taken and divided into four groups i.e. tooth enamel, glass ionomer cement, composite and compomer. Four commercially available drinks were chosen these were Coca -Cola, Nimbooz, Frooti and Yakult. The pH of each drink was measured. Each group was immersed in various experimental drinks for a period of 14 days. The erosive potential of each drink was measured by calculating the change in average surface roughness of these groups after the immersion protocol in various drinks. The data analysis was done by One Way Anova, Post-Hoc Bonferroni, and paired t –test. Results Group II-GIC showed highest values for mean of change in average surface roughness and the values were statistically significant (p<0.001) with tooth enamel, composite and compomer (p=0.002). Coca-cola showed the highest erosive potential and Yakult showed the lowest, there was no statistical significant difference between the results shown by Yakult and Frooti. Conclusion Characteristics which may promote erosion of enamel and tooth coloured restorative materials were surface texture of the material and pH of the drinks. PMID:27437343

  14. Changes in Water Sorption and Solubility of Dental Adhesive Systems after Cigarette Smoke

    PubMed Central

    Vitória, Lívia Andrade; Aguiar, Thaiane Rodrigues; Santos, Poliana Ramos Braga; Cavalcanti, Andrea Nóbrega

    2013-01-01

    Aim. To evaluate the effect of cigarette smoke on water sorption and solubility of four adhesive systems. Materials and Methods. Sixteen disks of each adhesive system were prepared (Adper Scotchbond Multipurpose Adhesive (SA); Adper Scotchbond Multipurpose Adhesive System (Adhesive + Primer) (SAP); Adper Single Bond Plus (SB); Adper Easy One (EO)). Specimens were desiccated until a constant mass was obtained and divided into two groups (n = 8). One-half of the specimens were immersed in deionized water, while the other half were also immersed, but with daily exposure to tobacco smoke. After 21 days, disks were measured again and stored in desiccators until constant mass was achieved. Data were calculated according to ISO specifications and statistically analyzed. Results. The tobacco smoke only significantly affected the water sorption and solubility of EO. There were significant differences in both analyses among materials tested. The SB exhibited the highest water sorption, followed by EO, which demonstrated significantly higher solubility values than SB. The SA and SAP showed low water sorption and solubility, and there were no significant differences between the two. Conclusion. Regardless of smoke exposure, both simplified adhesive systems presented an inferior performance that could be related to the complex mixture of components in such versions. PMID:23984078

  15. Dental OCT

    NASA Astrophysics Data System (ADS)

    Wilder-Smith, Petra; Otis, Linda; Zhang, Jun; Chen, Zhongping

    This chapter describes the applications of OCT for imaging in vivo dental and oral tissue. The oral cavity is a diverse environment that includes oral mucosa, gingival tissues, teeth and their supporting structures. Because OCT can image both hard and soft tissues of the oral cavity at high resolution, it offers the unique capacity to identity dental disease before destructive changes have progressed. OCT images depict clinically important anatomical features such as the location of soft tissue attachments, morphological changes in gingival tissue, tooth decay, enamel thickness and decay, as well as the structural integrity of dental restorations. OCT imaging allows for earlier intervention than is possible with current diagnostic modalities.

  16. A study on the promotion and suppression of demineralization of human dental hard tissues and hydroxyapatite.

    PubMed

    Odajima, T; Onishi, M

    1998-01-01

    Demineralization of human dental enamel and dentine and their analogue compound, hydroxyapatite, was examined by using pH-metry to measure the time-courses of neutralization of acetate, formate, lactate or propionate buffer solution or of acidification of EDTA solution. The extent of neutralization by enamel, dentine and hydroxyapatite was different for each acid but increased in the same order: propionate, acetate, lactate and formate. This order was consistent with that of the K values of these acids. The pH-metry was used to determine the influences of sodium chloride and sucrose on demineralization of enamel, dentine and hydroxyapatite by acetate, formate, lactate and propionate and by EDTA. The demineralization by these bioorganic acids was suppressed by sucrose but promoted by sodium chloride, except that the demineralization of enamel by acetate and propionate was little affected. The demineralization of enamel, dentine and hydroxyapatite by EDTA was little affected by sucrose but promoted by sodium chloride. The promotive effect of sodium chloride on demineralization may be due to the increasing of solubility product by this salt and the suppressive effect of sucrose may be due to the formation of a calcium saccharate formed from the sucrose reacted with calcium on the surface of apatite crystal and/or the reduction of solubility product by the sucrose. In this study, it was also ascertained that the use of pH-metry made it possible to determine easily the demineralization. PMID:11063021

  17. Susceptibility of representative dental pathogens to inactivation by the PDT with water-soluble photosensitizers

    NASA Astrophysics Data System (ADS)

    Angelov, Ivan; Mantareva, Vanya; Kussovski, Veselin; Worle, Diter; Kisov, Hristo; Belcheva, Marieta; Georgieva, Tzvetelina; Dimitrov, Slavcho

    2010-09-01

    In the recent decade the applications of photodynamic therapy (PDT) rapidly increase in several topics and one of areas where the PDT in the future will be play significant role is dentistry. The different photosensitizing complexes with a good water solubility and with absorption with an intensive maximum in the red region (630-690 nm), which makes them suitable for photodynamic treatments, were investigated. The photochemical properties of complexes for singlet oxygen generation were investigated and were shown relations between uptake levels and light intensity to achieve increase in photodynamic efficacy. Photodynamic efficacy against fungi Candida albicans and bacteria's E. faecalis, MRSA and S. Mutans in planktonic media was evaluated. The high photodynamic efficacy was shown for SiPc at very low concentrations (0.9 μM) and light doses of 50 J cm-2 by intensity of light 60 mW cm-2. The photodynamic response for E. faecalis, MRSA and S. Mutans, after treatments with different photosensitizers show strong dependence on concentrations of photsensitzers and micro organisms. The level of inactivation of the pathogen bacteria's from 1-2 degree of initial concentration up to full inactivation was observed. The studied complexes were compared to the recently studied Methylene blue, Haematoporphyrine and tetra-methylpirydiloxy Zn(II)- phthalocyanines and experimental results show that some of them have a good potential for inactivation of representative pathogenic bacterial strains. Experimental results also indicate that photodynamic therapy appears an effective method for inactivation of oral pathogenic bacterias and fungi.

  18. Susceptibility of representative dental pathogens to inactivation by the PDT with water-soluble photosensitizers

    NASA Astrophysics Data System (ADS)

    Angelov, Ivan; Mantareva, Vanya; Kussovski, Veselin; Worle, Diter; Kisov, Hristo; Belcheva, Marieta; Georgieva, Tzvetelina; Dimitrov, Slavcho

    2011-02-01

    In the recent decade the applications of photodynamic therapy (PDT) rapidly increase in several topics and one of areas where the PDT in the future will be play significant role is dentistry. The different photosensitizing complexes with a good water solubility and with absorption with an intensive maximum in the red region (630-690 nm), which makes them suitable for photodynamic treatments, were investigated. The photochemical properties of complexes for singlet oxygen generation were investigated and were shown relations between uptake levels and light intensity to achieve increase in photodynamic efficacy. Photodynamic efficacy against fungi Candida albicans and bacteria's E. faecalis, MRSA and S. Mutans in planktonic media was evaluated. The high photodynamic efficacy was shown for SiPc at very low concentrations (0.9 μM) and light doses of 50 J cm-2 by intensity of light 60 mW cm-2. The photodynamic response for E. faecalis, MRSA and S. Mutans, after treatments with different photosensitizers show strong dependence on concentrations of photsensitzers and micro organisms. The level of inactivation of the pathogen bacteria's from 1-2 degree of initial concentration up to full inactivation was observed. The studied complexes were compared to the recently studied Methylene blue, Haematoporphyrine and tetra-methylpirydiloxy Zn(II)- phthalocyanines and experimental results show that some of them have a good potential for inactivation of representative pathogenic bacterial strains. Experimental results also indicate that photodynamic therapy appears an effective method for inactivation of oral pathogenic bacterias and fungi.

  19. Variation in enamel thickness within the genus Homo.

    PubMed

    Smith, Tanya M; Olejniczak, Anthony J; Zermeno, John P; Tafforeau, Paul; Skinner, Matthew M; Hoffmann, Almut; Radovčić, Jakov; Toussaint, Michel; Kruszynski, Robert; Menter, Colin; Moggi-Cecchi, Jacopo; Glasmacher, Ulrich A; Kullmer, Ottmar; Schrenk, Friedemann; Stringer, Chris; Hublin, Jean-Jacques

    2012-03-01

    Recent humans and their fossil relatives are classified as having thick molar enamel, one of very few dental traits that distinguish hominins from living African apes. However, little is known about enamel thickness in the earliest members of the genus Homo, and recent studies of later Homo report considerable intra- and inter-specific variation. In order to assess taxonomic, geographic, and temporal trends in enamel thickness, we applied micro-computed tomographic imaging to 150 fossil Homo teeth spanning two million years. Early Homo postcanine teeth from Africa and Asia show highly variable average and relative enamel thickness (AET and RET) values. Three molars from South Africa exceed Homo AET and RET ranges, resembling the hyper thick Paranthropus condition. Most later Homo groups (archaic European and north African Homo, and fossil and recent Homo sapiens) possess absolutely and relatively thick enamel across the entire dentition. In contrast, Neanderthals show relatively thin enamel in their incisors, canines, premolars, and molars, although incisor AET values are similar to H. sapiens. Comparisons of recent and fossil H. sapiens reveal that dental size reduction has led to a disproportionate decrease in coronal dentine compared with enamel (although both are reduced), leading to relatively thicker enamel in recent humans. General characterizations of hominins as having 'thick enamel' thus oversimplify a surprisingly variable craniodental trait with limited taxonomic utility within a genus. Moreover, estimates of dental attrition rates employed in paleodemographic reconstruction may be biased when this variation is not considered. Additional research is necessary to reconstruct hominin dietary ecology since thick enamel is not a prerequisite for hard-object feeding, and it is present in most later Homo species despite advances in technology and food processing. PMID:22361504

  20. The Molecular Basis of Hereditary Enamel Defects in Humans

    PubMed Central

    Carrion, I.A.; Morris, C.

    2015-01-01

    The formation of human enamel is highly regulated at the molecular level and involves thousands of genes. Requisites for development of this highly mineralized tissue include cell differentiation; production of a unique extracellular matrix; processing of the extracellular matrix; altering of cell function during different stages of enamel formation; cell movement and attachment; regulation of ion and protein movement; and regulation of hydration, pH, and other conditions of the microenvironment, to name just a few. Not surprising, there is a plethora of hereditary conditions with an enamel phenotype. The objective of this review was to identify the hereditary conditions listed on Online Mendelian Inheritance in Man (OMIM) that have an associated enamel phenotype and whether a causative gene has been identified. The OMIM database was searched with the terms amelogenesis, enamel, dental, and tooth, and all results were screened by 2 individuals to determine if an enamel phenotype was identified. Gene and gene product function was reviewed on OMIM and from publications identified in PubMed. The search strategy revealed 91 conditions listed in OMIM as having an enamel phenotype, and of those, 71 have a known molecular etiology or linked genetic loci. The purported protein function of those conditions with a known genetic basis included enzymes, regulatory proteins, extracellular matrix proteins, transcription factors, and transmembrane proteins. The most common enamel phenotype was a deficient amount of enamel, or enamel hypoplasia, with hypomineralization defects being reported less frequently. Knowing these molecular defects allows an initial cataloging of molecular pathways that lead to hereditary enamel defects in humans. This knowledge provides insight into the diverse molecular pathways involved in enamel formation and can be useful when searching for the genetic etiology of hereditary conditions that involve enamel. PMID:25389004

  1. Australopithecine enamel prism patterns.

    PubMed

    Vrba, E S; Grine, F E

    1978-11-24

    Following a recent suggestion that tooth enamel prism shape differs within Hominoidea, the teeth of a number of extinct and extant hominoid species were analyzed by scanning electron microscopy. The enamel prism patterns of some gracile and robust australopithecine specimens from Sterkfontein, Swartkrans, and Kromdraai are recorded. The characteristic arrangements of enamel prisms in all modern and extinct hominoid species were found to be essentially similar. The implications of enamel prisms for phylogenetic deduction in Hominoidea are discussed. PMID:102032

  2. Enamel hypoplasia: challenges of esthetic restorative treatment.

    PubMed

    Ruschel, Vanessa Carla; Araújo, Élito; Bernardon, Jussara Karina; Lopes, Guilherme Carpena

    2016-01-01

    Enamel defects, such as white or yellow-brown spots, usually cause problems that are more esthetic than functional. Enamel hypoplasia may be the result of hereditary, systemic, or local factors. Dental trauma is a local etiologic factor. It is relatively common in the primary dentition and can cause defects on the surface of permanent successors. Treatment for such defects can differ, depending on the depth of the spots. For deeper white-spot lesions, a composite resin restoration may be necessary. This is an excellent mode of treatment, due to both its low cost and its conservation of healthy tooth structure. The objective of this case report is to describe composite resin restoration of a maxillary central incisor affected by enamel hypoplasia. PMID:27599287

  3. Modelling of micromachining of human tooth enamel by erbium laser radiation

    NASA Astrophysics Data System (ADS)

    Belikov, A. V.; Skrypnik, A. V.; Shatilova, K. V.

    2014-08-01

    We consider a 3D cellular model of human tooth enamel and a photomechanical cellular model of enamel ablation by erbium laser radiation, taking into account the structural peculiarities of enamel, energy distribution in the laser beam cross section and attenuation of laser energy in biological tissue. The surface area of the texture in enamel is calculated after its micromachining by erbium laser radiation. The influence of the surface area on the bond strength of enamel with dental filling materials is discussed. A good correlation between the computer simulation of the total work of adhesion and experimentally measured bond strength between the dental filling material and the tooth enamel after its micromachining by means of YAG : Er laser radiation is attained.

  4. Modelling of micromachining of human tooth enamel by erbium laser radiation

    SciTech Connect

    Belikov, A V; Skrypnik, A V; Shatilova, K V

    2014-08-31

    We consider a 3D cellular model of human tooth enamel and a photomechanical cellular model of enamel ablation by erbium laser radiation, taking into account the structural peculiarities of enamel, energy distribution in the laser beam cross section and attenuation of laser energy in biological tissue. The surface area of the texture in enamel is calculated after its micromachining by erbium laser radiation. The influence of the surface area on the bond strength of enamel with dental filling materials is discussed. A good correlation between the computer simulation of the total work of adhesion and experimentally measured bond strength between the dental filling material and the tooth enamel after its micromachining by means of YAG : Er laser radiation is attained. (laser biophotonics)

  5. Evolution of Klk4 and enamel maturation in eutherians.

    PubMed

    Kawasaki, Kazuhiko; Hu, Jan C-C; Simmer, James P

    2014-09-01

    Kallikrein-related peptidase 4 (KLK4) is a secreted serine protease that degrades residual enamel proteins to facilitate their removal by ameloblasts, which increases mineralization and hardens the enamel. Mutations in human KLK4 cause hypomaturation amelogenesis imperfecta. Enamel formed by Klk4 null mice is normal in thickness and prism structure, but the enamel layer retains proteins, is hypomineralized, and undergoes rapid attrition following tooth eruption. We searched multiple databases, retrieved Klk4 and Klk5 from various mammalian genomes, and identified Klk4 in 46 boreoeutherian genomes. In non-Boreoeutheria, Klk4 was detected in only one afrotherian genome (as a pseudogene), and not in the other six afrotherian, two xenarthran, or three marsupial genomes. In contrast, Klk5 was detected in both marsupial and eutherian mammals. Our phylogenetic and mutation rate analyses support the hypothesis that Klk4 arose from Klk5 by gene duplication near the divergence of Afrotheria, Xenarthra and Boreoeutheria, and that functionally-differentiated Klk4 survived only in Boreoeutheria. Afrotherian mammals share the feature of delayed dental eruption relative to boreoeutherian mammals. KLK4 shortens the time required for enamel maturation and could have alleviated negative selection following mutations that resulted in thicker enamel or earlier tooth eruption, without reducing enamel hardness or causing dental attrition. PMID:25153384

  6. Evolution of Klk4 and enamel maturation in eutherians

    PubMed Central

    Kawasaki, Kazuhiko; Hu, Jan C.-C; Simmer, James P.

    2014-01-01

    Kallikrein-related peptidase 4 (KLK4) is a secreted serine protease that degrades residual enamel proteins to facilitate their removal by ameloblasts, which increases mineralization and hardens the enamel. Mutations in human KLK4 cause hypomaturation amelogenesis imperfecta. Enamel formed by Klk4 null mice is normal in thickness and prism structure, but the enamel layer retains proteins, is hypomineralized, and undergoes rapid attrition following tooth eruption. We searched multiple databases, retrieved Klk4 and Klk5 from various mammalian genomes, and identified Klk4 in 47 boreoeutherian genomes. In non-Boreoeutheria, Klk4 was detected in only one afrotherian genome (as a pseudogene), and not in the other six afrotherian, two xenarthran, or three marsupial genomes. In contrast, Klk5 was detected in both marsupial and eutherian mammals. Our phylogenetic and mutation rate analyses support the hypothesis that Klk4 arose from Klk5 by gene duplication near the divergence of Afrotheria, Xenarthra and Boreoeutheria, and that functionally- differentiated Klk4 survived only in Boreoeutheria. Afrotherian mammals share the feature of delayed dental eruption relative to boreoeutherian mammals. KLK4 shortens the time required for enamel maturation and could have alleviated negative selection following mutations that resulted in thicker enamel or earlier tooth eruption, without reducing enamel hardness or causing dental attrition. PMID:25153384

  7. Effect of fluoride toothpastes on enamel demineralization

    PubMed Central

    Arnold, Wolfgang H; Dorow, Andreas; Langenhorst, Stephanie; Gintner, Zeno; Bánóczy, Jolan; Gaengler, Peter

    2006-01-01

    Background It was the aim of this study to investigate the effect of four different toothpastes with differing fluoride compounds on enamel remineralization. Methods A 3 × 3 mm window on the enamel surface of 90 human premolars was demineralized in a hydroxyethylcellulose solution at pH 4.8. The teeth were divided into 6 groups and the lower half of the window was covered with varnish serving as control. The teeth were immersed in a toothpaste slurry containing: placebo tooth paste (group 1); remineralization solution (group 2); Elmex Anticaries (group 3); Elmex Sensitive (group 4); Blend-a-med Complete (group 5) and Colgate GRF (group 6). Ten teeth of each group were used for the determination of the F- content in the superficial enamel layer and acid solubility of enamel expressed in soluble phosphorus. Of 6 teeth of each group serial sections were cut and investigated with polarization light microscopy (PLM) and quantitative energy dispersive X-ray analysis (EDX). Results The PLM results showed an increased remineralization of the lesion body in the Elmex Anticaries, Elmex Sensitive and Colgate GRF group but not in the Blend-a-med group. A statistically significant higher Ca content was found in the Elmex Anticaries group. The fluoride content in the superficial enamel layer was significantly increased in both Elmex groups and the Blend-a-med group. Phosphorus solubility was significantly decreased in both Elmex groups and the Blend-a-med group. Conclusion It can be concluded that amine fluoride compounds in toothpastes result in a clearly marked remineralization of caries like enamel lesions followed by sodium fluoride and sodium monofluorophosphate formulations. PMID:16776820

  8. Enamel surface changes caused by hydrogen sulfide

    PubMed Central

    Yamaguchi, Takao; Hanabusa, Masao; Hosoya, Noriyasu; Chiba, Toshie; Yoshida, Takumasa; Morito, Akiyuki

    2015-01-01

    Background: Volatile sulfur compounds (VSCs) produced inside the mouth are a well-known cause of halitosis. Recent studies have suggested that VSCs modify the pathology of periodontitis by encouraging the migration of bacterial toxins associated with increased permeability of gingival epithelia, and enhancing the production of matrix metalloproteinases in gingival connective tissue. Nonetheless, the effects on the enamel of direct exposure to VSCs within the oral cavity remain unclear. In the present study, we observed the effects of VSCs in the form of hydrogen sulfide (H2S) on enamel surfaces and determined their effects on restorations. Materials and Methods: Extracted human tooth and bovine tooth samples were divided into the H2S experimental side and the control side. We observed the effects of H2S on enamel surfaces using electron microscopy and conducted a shear test. Results: We found that exposure to H2S obscured the enamel surface's crystal structure. The surface also exhibited coarseness and reticular changes. Shear testing did not reveal any differences in bond strength. Conclusions: Our findings suggested that H2S occurring inside the mouth causes changes to the crystal structure of the enamel surface that can lead to tooth wear, but that it does not diminish the effects of dental bonding in adhesive restorations. PMID:26752833

  9. Residual energy deposition in dental enamel during IR laser ablation at 2.79, 2.94, 9.6, and 10.6 μm

    NASA Astrophysics Data System (ADS)

    Ragadio, Jerome N.; Lee, Christian K.; Fried, Daniel

    2000-03-01

    The objective of this study was to measure the residual heat deposition during laser ablation at those IR laser wavelengths best suited for the removal of dental caries. The principal factor limiting the rate of laser ablation of dental hard tissue is the risk of excessive heat accumulation in the tooth, which has the potential for causing damage to the pulp. Optimal laser ablation systems minimize the residual energy deposition in the tooth by transferring deposited laser energy to kinetic and internal energy of ejected tissue components. The residual heat deposition in the tooth was measured at laser wavelengths of 2.79, 2.94, 9.6 and 10.6 micrometer and pulse widths of 150 ns - 150 microsecond(s) . The residual energy was at a minimum for fluences well above the ablation threshold where it saturates at values from 25 - 70% depending on pulse duration and wavelength for the systems investigated. The lowest values of the residual energy were measured for short (less than 20 microseconds) CO2 laser pulses at 9.6 micrometer and for Q-switched erbium laser pulses. This work was supported by NIH/NIDCR R29DE12091 and the Center for Laser Applications in Medicine, DOE DEFG0398ER62576.

  10. Enamel thickness and development in a third permanent molar of Gigantopithecus blacki.

    PubMed

    Dean, M Christopher; Schrenk, Friedemann

    2003-11-01

    A ground section was prepared from a lower right M3 attributed to Gigantopithecus blacki as close as possible to axial plane of the mesial cusps. Daily cross striations were imaged, measured and counted in each cusp using polarised light microscopy. Long-period striae of Retzius were counted in the lateral enamel and their periodicity determined from counts and measurements of daily cross striations between adjacent striae. Cross striation spacings in the cusps were between 3.8 microm at the enamel dentine junction and 6 microm close to the enamel surface. Cuspal enamel formation times were long (800 days in the protoconid and 620 days in the metaconid). Linear enamel thickness was as much as 3.75 mm in the protoconid. There were 63 and 61 long-period striae of Retzius in the mesial aspects of the lateral enamel and the periodicity was 11 days. Lateral enamel formation took 1493 and 1291 days and when summed with cuspal enamel formation times totalled 4 years in the protoconid and 3.5 in the metaconid. Relative enamel thickness was 23, calculated through the mesial cusps. This falls short of that in the so-called 'thick hyper-thick' enamel described in 'robust' australopithecines to which Gigantopithecus blacki has previously been compared in both its dental and mandibular morphology. With respect to enamel thickness, therefore, Gigantopithecus blacki falls squarely among an increasingly large number of Miocene hominoids that can all be described as having 'thick enamel'. PMID:14624748

  11. Recovery and identification of mature enamel proteins in ancient teeth.

    PubMed

    Porto, Isabel M; Laure, Helen J; Tykot, Robert H; de Sousa, Frederico B; Rosa, Jose C; Gerlach, Raquel F

    2011-12-01

    Proteins in mineralized tissues provide a window to the past, and dental enamel is peculiar in being highly resistant to diagenesis and providing information on a very narrow window of time, such as the developing period; however, to date, complete proteins have not been extracted successfully from ancient teeth. In this work we tested the ability of a whole-crown micro-etch technique to obtain enamel protein samples from mature enamel of recently extracted (n = 2) and ancient (n = 2; ad 800 to 1100) third molars. Samples were analyzed using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF/TOF) mass spectrometry, and the resulting spectra were searched against the Swiss-Prot protein database using the Mascot software for protein identification. In our protocol, the separation of proteins in gel is not necessary. Successful identification of specific enamel proteins was obtained after whole-crown superficial enamel etching with 10% HCl. Most protein fragments recovered from dry teeth and mummy teeth contained amino-terminal amelogenin peptides. Only one peptide specific for the amelogenin X-isoform was identified. In conclusion, the reported techniques allowed the successful recovery of proteins specific to dental enamel from samples obtained in a very conservative manner, which may also be important in forensic and/or archeological science. PMID:22243232

  12. Enamel alteration following tooth bleaching and remineralization.

    PubMed

    Coceska, Emilija; Gjorgievska, Elizabeta; Coleman, Nichola J; Gabric, Dragana; Slipper, Ian J; Stevanovic, Marija; Nicholson, John W

    2016-06-01

    The purpose of this study was to compare the effects of professional tooth whitening agents containing highly concentrated hydrogen peroxide (with and without laser activation), on the enamel surface; and the potential of four different toothpastes to remineralize any alterations. The study was performed on 50 human molars, divided in two groups: treated with Opalescence(®) Boost and Mirawhite(®) Laser Bleaching. Furthermore, each group was divided into five subgroups, a control one and 4 subgroups remineralized with: Mirasensitive(®) hap+, Mirawhite(®) Gelleѐ, GC Tooth Mousse™ and Mirafluor(®) C. The samples were analysed by SEM/3D-SEM-micrographs, SEM/EDX-qualitative analysis and SEM/EDX-semiquantitative analysis. The microphotographs show that both types of bleaching cause alterations: emphasized perikymata, erosions, loss of interprizmatic substance; the laser treatment is more aggressive and loss of integrity of the enamel is determined by shearing off the enamel rods. In all samples undergoing remineralization deposits were observed, those of toothpastes based on calcium phosphate technologies seem to merge with each other and cover almost the entire surface of the enamel. Loss of integrity and minerals were detected only in the line-scans of the sample remineralized with GC Tooth Mousse™. The semiquantitative EDX analysis of individual elements in the surface layer of the enamel indicates that during tooth-bleaching with HP statistically significant loss of Na and Mg occurs, whereas the bleaching in combination with a laser leads to statistically significant loss of Ca and P. The results undoubtedly confirm that teeth whitening procedures lead to enamel alterations. In this context, it must be noted that laser bleaching is more aggressive for dental substances. However, these changes are reversible and can be repaired by application of remineralization toothpastes. PMID:27197087

  13. Liquid White Enamel.

    ERIC Educational Resources Information Center

    Widmar, Marge

    1985-01-01

    A secondary teacher describes how she has her students use liquid white enamel. With the enameling process, students can create lasting, exciting artwork. They can exercise an understanding of design and color while learning the value of careful, sustained craft skills. (RM)

  14. Keratins as components of the enamel organic matrix.

    PubMed

    Duverger, Olivier; Beniash, Elia; Morasso, Maria I

    2016-01-01

    Dental enamel is the hardest tissue in the human body, and although it starts as a tissue rich in proteins, by the time of eruption of the tooth in the oral cavity only a small fraction of the protein remains. While this organic matrix of enamel represents less than 1% by weight it plays essential roles in improving both toughness and resilience to chemical attacks. Despite the fact that the first studies of the enamel matrix began in the 19th century, its exact composition and mechanisms of its function remain poorly understood. It was proposed that keratin or a keratin-like primitive epithelial component exists in mature enamel, however due to the extreme insolubility of its organic matrix the presence of keratins there was never clearly established. We have recently identified expression of a number of hair keratins in ameloblasts, the enamel secreting cells, and demonstrated their incorporation into mature enamel. Mutation in epithelial hair keratin KRT75 leads to a skin condition called pseudofollicularis barbae. Carriers of this mutation have an altered enamel structure and mechanical properties. Importantly, these individuals have a much higher prevalence of caries. To the best of our knowledge, this is the first study showing a direct link between a mutation in a protein-coding region of a gene and increased caries rates. In this paper we present an overview of the evidence of keratin-like material in enamel that has accumulated over the last 150years. Furthermore, we propose potential mechanisms of action of KTR75 in enamel and highlight the clinical implications of the link between mutations in KRT75 and caries. Finally, we discuss the potential use of keratins for enamel repair. PMID:26709044

  15. Stress Response Pathways in Ameloblasts: Implications for Amelogenesis and Dental Fluorosis

    PubMed Central

    Sierant, Megan L.; Bartlett, John D.

    2012-01-01

    Human enamel development of the permanent teeth takes place during childhood and stresses encountered during this period can have lasting effects on the appearance and structural integrity of the enamel. One of the most common examples of this is the development of dental fluorosis after childhood exposure to excess fluoride, an elemental agent used to increase enamel hardness and prevent dental caries. Currently the molecular mechanism responsible for dental fluorosis remains unknown; however, recent work suggests dental fluorosis may be the result of activated stress response pathways in ameloblasts during the development of permanent teeth. Using fluorosis as an example, the role of stress response pathways during enamel maturation is discussed. PMID:23745169

  16. Dental Health in TSC

    MedlinePlus

    ... to occur in nearly 100% of the TSC population. Not all dental pits are cavities; they are just areas where enamel did not form, but can be an area where food can build up and start a cavity. Gums The gums may have small areas of growth called gingival fibromas , which are mostly harmless and ...

  17. Biological synthesis of tooth enamel instructed by an artificial matrix

    PubMed Central

    Huang, Z.; Newcomb, C.J.; Bringas, P.; Stupp, S.I.; Snead, M.L.

    2010-01-01

    The regenerative capability of enamel, the hardest tissue in the vertebrate body, is fundamentally limited due to cell apoptosis following maturation of the tissue. Synthetic strategies to promote enamel formation have the potential to repair damage, increase the longevity of teeth and improve the understanding of the events leading to tissue formation. Using a self-assembling bioactive matrix, we demonstrate the ability to induce ectopic formation of enamel at chosen sites adjacent to a mouse incisor cultured in vivo under the kidney capsule. The resulting material reveals the highly organized, hierarchical structure of hydroxyapatite crystallites similar to native enamel. This artificially triggered formation of organized mineral demonstrates a pathway for developing cell fabricated materials for treatment of dental caries, the most ubiquitous disease in man. Additionally, the artificial matrix provides a unique tool to probe cellular mechanisms involved in tissue formation further enabling the development of tooth organ replacements. PMID:20869764

  18. Enamel microabrasion: An overview of clinical and scientific considerations.

    PubMed

    Pini, Núbia Inocencya Pavesi; Sundfeld-Neto, Daniel; Aguiar, Flavio Henrique Baggio; Sundfeld, Renato Herman; Martins, Luis Roberto Marcondes; Lovadino, José Roberto; Lima, Débora Alves Nunes Leite

    2015-01-16

    Superficial stains and irregularities of the enamel are generally what prompt patients to seek dental intervention to improve their smile. These stains or defects may be due to hypoplasia, amelogenesis imperfecta, mineralized white spots, or fluorosis, for which enamel microabrasion is primarily indicated. Enamel microabrasion involves the use of acidic and abrasive agents, such as with 37% phosphoric acid and pumice or 6% hydrochloric acid and silica, applied to the altered enamel surface with mechanical pressure from a rubber cup coupled to a rotatory mandrel of a low-rotation micromotor. If necessary, this treatment can be safely combined with bleaching for better esthetic results. Recent studies show that microabrasion is a conservative treatment when the enamel wear is minimal and clinically imperceptible. The most important factor contributing to the success of enamel microabrasion is the depth of the defect, as deeper, opaque stains, such as those resulting from hypoplasia, cannot be resolved with microabrasion, and require a restorative approach. Surface enamel alterations that result from microabrasion, such as roughness and microhardness, are easily restored by saliva. Clinical studies support the efficacy and longevity of this safe and minimally invasive treatment. The present article presents the clinical and scientific aspects concerning the microabrasion technique, and discusses the indications for and effects of the treatment, including recent works describing microscopic and clinical evaluations. PMID:25610848

  19. Enamel microabrasion: An overview of clinical and scientific considerations

    PubMed Central

    Pini, Núbia Inocencya Pavesi; Sundfeld-Neto, Daniel; Aguiar, Flavio Henrique Baggio; Sundfeld, Renato Herman; Martins, Luis Roberto Marcondes; Lovadino, José Roberto; Lima, Débora Alves Nunes Leite

    2015-01-01

    Superficial stains and irregularities of the enamel are generally what prompt patients to seek dental intervention to improve their smile. These stains or defects may be due to hypoplasia, amelogenesis imperfecta, mineralized white spots, or fluorosis, for which enamel microabrasion is primarily indicated. Enamel microabrasion involves the use of acidic and abrasive agents, such as with 37% phosphoric acid and pumice or 6% hydrochloric acid and silica, applied to the altered enamel surface with mechanical pressure from a rubber cup coupled to a rotatory mandrel of a low-rotation micromotor. If necessary, this treatment can be safely combined with bleaching for better esthetic results. Recent studies show that microabrasion is a conservative treatment when the enamel wear is minimal and clinically imperceptible. The most important factor contributing to the success of enamel microabrasion is the depth of the defect, as deeper, opaque stains, such as those resulting from hypoplasia, cannot be resolved with microabrasion, and require a restorative approach. Surface enamel alterations that result from microabrasion, such as roughness and microhardness, are easily restored by saliva. Clinical studies support the efficacy and longevity of this safe and minimally invasive treatment. The present article presents the clinical and scientific aspects concerning the microabrasion technique, and discusses the indications for and effects of the treatment, including recent works describing microscopic and clinical evaluations. PMID:25610848

  20. Enamel hypoplasia and its role in identification of individuals: A review of literature

    PubMed Central

    Kanchan, Tanuj; Machado, Meghna; Rao, Ashwin; Krishan, Kewal; Garg, Arun K.

    2015-01-01

    Identification of individuals is the mainstay of any forensic investigation especially in cases of mass disasters when mutilated remains are brought for examination. Dental examination helps in establishing the identity of an individual and thus, has played a vital role in forensic investigation process since long. In this regard, description on the role of enamel hypoplasia is limited in the literature. The present article reviews the literature on the enamel hypoplasia and discusses its utility in forensic identification. Enamel hypoplasia is a surface defect of the tooth crown caused by disturbance of enamel matrix secretion. Enamel defects can be congenital or acquired. In cases of mass disasters, or when the body is completely charred, putrefied and mutilated beyond recognition, the unique dental features can help in identification of the victims. PMID:26097340

  1. Enamel hypoplasia and its role in identification of individuals: A review of literature.

    PubMed

    Kanchan, Tanuj; Machado, Meghna; Rao, Ashwin; Krishan, Kewal; Garg, Arun K

    2015-01-01

    Identification of individuals is the mainstay of any forensic investigation especially in cases of mass disasters when mutilated remains are brought for examination. Dental examination helps in establishing the identity of an individual and thus, has played a vital role in forensic investigation process since long. In this regard, description on the role of enamel hypoplasia is limited in the literature. The present article reviews the literature on the enamel hypoplasia and discusses its utility in forensic identification. Enamel hypoplasia is a surface defect of the tooth crown caused by disturbance of enamel matrix secretion. Enamel defects can be congenital or acquired. In cases of mass disasters, or when the body is completely charred, putrefied and mutilated beyond recognition, the unique dental features can help in identification of the victims. PMID:26097340

  2. The effect of ZrO2 and TiO 2 on solubility and strength of apatite-mullite glass-ceramics for dental applications.

    PubMed

    Fathi, Hawa M; Miller, Cheryl; Stokes, Christopher; Johnson, Anthony

    2014-03-01

    The effect of ZrO2 and TiO2 on the chemical and mechanical properties of apatite-mullite glass-ceramics was investigated after sample preparation according to the ISO (2768:2008) recommendations for dental ceramics. All materials were characterized using differential thermal analysis, X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. X-ray fluorescence spectroscopy was used to determine the concentrations of elements present in all materials produced. The chemical solubility test and the biaxial flexural strength (BFS) test were then carried out on all the samples. The best solubility value of 242 ± 61 μg/cm(2) was obtained when HG1T was heat-treated for 1 h at the glass transition temperature plus 20 °C (Tg + 20 °C) followed by 5 h at 1200 °C. The highest BFS value of 174 ± 38 MPa was achieved when HG1Z and HG1Z+T were heat-treated for 1 h at the Tg + 20 °C followed by 7 h at 1200 °C. The present study has demonstrated that the addition of TiO2 to the reference composition showed promise in both the glass and heat-treated samples. However, ZrO2 is an effective agent for developing the solubility or the mechanical properties of an apatite-mullite glass-ceramic separately but does not improve the solubility and the BFS simultaneously. PMID:24249630

  3. Thermal effects of lasers on dental tissues

    SciTech Connect

    Launay, Y.; Mordon, S.; Cornil, A.; Brunetaud, J.M.; Moschetto, Y.

    1987-01-01

    The thermal effects of Nd:YAG, argon, and CO/sub 2/ laser beams are observed on enamel, dentin, and dental pulp by means of computerized infrared thermography and thermocouple. This study shows that the Nd:YAG laser beam deeply diffuses through the enamel and dentin to the pulp. The argon laser effects are inconsistent depending on whether the enamel surface is cleaned, but after cleaning, the superficial and deep temperatures are low. With the CO/sub 2/ laser, the enamel and dentin surfaces reach very high temperatures, but only low temperatures are measured in the pulp chamber.

  4. Structural Morphology of Molars in Large Mammalian Herbivores: Enamel Content Varies between Tooth Positions

    PubMed Central

    Winkler, Daniela E.; Kaiser, Thomas M.

    2015-01-01

    The distribution of dental tissues in mammalian herbivores can be very different from taxon to taxon. While grazers tend to have more elaborated and complexly folded enamel ridges, browsers have less complex enamel ridges which can even be so far reduced that they are completely lost. The gradient in relative enamel content and complexity of structures has so far not been addressed within a single species. However, several studies have noted tooth position specific wear rates in small mammals (rabbits, guinea pigs) which may be related to individual tooth morphology. We investigate whether differentiated enamel content by tooth position is also to be found in large herbivores. We use CT-scanning techniques to quantify relative enamel content in upper and lower molar teeth of 21 large herbivorous mammal species. By using a broad approach and including both perissodactyls and artiodactyls, we address phylogenetic intraspecific differences in relative enamel content. We find that enamel is highly unevenly distributed among molars (upper M1, M2, M3 and lower m1, m2, m3) in most taxa and that relative enamel content is independent of phylogeny. Overall, relative enamel content increases along the molar tooth row and is significantly higher in lower molars compared to upper molars. We relate this differential enamel content to prolonged mineralisation in the posterior tooth positions and suggest a compensatory function of m3 and M3 for functional losses of anterior teeth. PMID:26313359

  5. Enamel hypoplasia in the deciduous teeth of great apes: variation in prevalence and timing of defects.

    PubMed

    Lukacs, J R

    2001-11-01

    The prevalence of enamel hypoplasia in the deciduous teeth of great apes has the potential to reveal episodes of physiological stress in early stages of ontogenetic development. However, little is known about enamel defects of deciduous teeth in great apes. Unresolved questions addressed in this study are: Do hypoplastic enamel defects occur with equal frequency in different groups of great apes? Are enamel hypoplasias more prevalent in the deciduous teeth of male or female apes? During what phase of dental development do enamel defects tend to form? And, what part of the dental crown is most commonly affected? To answer these questions, infant and juvenile skulls of two sympatric genera of great apes (Gorilla and Pan) were examined for dental enamel hypoplasias. Specimens from the Powell-Cotton Museum (Quex Park, UK; n = 107) are reported here, and compared with prior findings based on my examination of juvenile apes at the Cleveland Museum of Natural History (Hamman-Todd Collection; n = 100) and Smithsonian Institution (National Museum of Natural History; n = 36). All deciduous teeth were examined by the author with a x10 hand lens, in oblique incandescent light. Defects were classified using Fédération Dentaire International (FDI)/Defects of Dental Enamel (DDE) standards; defect size and location on the tooth crown were measured and marked on dental outline charts. Enamel defects of ape deciduous teeth are most common on the labial surface of canine teeth. While deciduous incisor and molar teeth consistently exhibit similar defects with prevalences of approximately 10%, canines average between 70-75%. Position of enamel defects on the canine crown was analyzed by dividing it into three zones (apical, middle, and cervical) and calculating defect prevalence by zone. Among gorillas, enamel hypoplasia prevalence increases progressively from the apical zone (low) to the middle zone to the cervical zone (highest), in both maxillary and mandibular canine teeth

  6. Development of Amelogenin-chitosan Hydrogel for In Vitro Enamel Regrowth with a Dense Interface

    PubMed Central

    Ruan, Qichao; Moradian-Oldak, Janet

    2015-01-01

    Biomimetic enamel reconstruction is a significant topic in material science and dentistry as a novel approach for the treatment of dental caries or erosion. Amelogenin has been proven to be a critical protein for controlling the organized growth of apatite crystals. In this paper, we present a detailed protocol for superficial enamel reconstruction by using a novel amelogenin-chitosan hydrogel. Compared to other conventional treatments, such as topical fluoride and mouthwash, this method not only has the potential to prevent the development of dental caries but also promotes significant and durable enamel restoration. The organized enamel-like microstructure regulated by amelogenin assemblies can significantly improve the mechanical properties of etched enamel, while the dense enamel-restoration interface formed by an in situ regrowth of apatite crystals can improve the effectiveness and durability of restorations. Furthermore, chitosan hydrogel is easy to use and can suppress bacterial infection, which is the major risk factor for the occurrence of dental caries. Therefore, this biocompatible and biodegradable amelogenin-chitosan hydrogel shows promise as a biomaterial for the prevention, restoration, and treatment of defective enamel. PMID:25046057

  7. Mechanisms and causes of wear in tooth enamel: implications for hominin diets

    PubMed Central

    Lucas, Peter W.; Omar, Ridwaan; Al-Fadhalah, Khaled; Almusallam, Abdulwahab S.; Henry, Amanda G.; Michael, Shaji; Thai, Lidia Arockia; Watzke, Jörg; Strait, David S.; Atkins, Anthony G.

    2013-01-01

    The wear of teeth is a major factor limiting mammalian lifespans in the wild. One method of describing worn surfaces, dental microwear texture analysis, has proved powerful for reconstructing the diets of extinct vertebrates, but has yielded unexpected results in early hominins. In particular, although australopiths exhibit derived craniodental features interpreted as adaptations for eating hard foods, most do not exhibit microwear signals indicative of this diet. However, no experiments have yet demonstrated the fundamental mechanisms and causes of this wear. Here, we report nanowear experiments where individual dust particles, phytoliths and enamel chips were slid across a flat enamel surface. Microwear features produced were influenced strongly by interacting mechanical properties and particle geometry. Quartz dust was a rigid abrasive, capable of fracturing and removing enamel pieces. By contrast, phytoliths and enamel chips deformed during sliding, forming U-shaped grooves or flat troughs in enamel, without tissue loss. Other plant tissues seem too soft to mark enamel, acting as particle transporters. We conclude that dust has overwhelming importance as a wear agent and that dietary signals preserved in dental microwear are indirect. Nanowear studies should resolve controversies over adaptive trends in mammals like enamel thickening or hypsodonty that delay functional dental loss. PMID:23303220

  8. SEM ANALYSIS OF THE ACID-ETCHED ENAMEL PATTERNS PROMOTED BY ACIDIC MONOMERS AND PHOSPHORIC ACIDS

    PubMed Central

    Shinohara, Mirela Sanae; de Oliveira, Marcelo Tavares; Hipólito, Vinícius Di; Giannin, Marcelo; de Goes, Mario Fernando

    2006-01-01

    Objective: Although self-etching bonding systems (SES) are indicated to prepare dental enamel for bonding, concerns have been expressed regarding their effectiveness. The aim of this study was to analyze the etching pattern (EP) of nine SES in comparison with 35% and 34% phosphoric acid etchants (FA) on intact (IN) and ground (GR) enamel surface. Materials and Methods: Twenty-two human third molars were sectioned in mesial-distal and buccal-lingual directions, and four dental fragments were obtained from each tooth. Half of the fragments were ground using 600-grit SiC paper and the other half remained intact. The fragments were randomly assigned into 22 groups, according to the texture of enamel surface (IN and GR) and the technique to etch the enamel (34% FA, 35% FA, AdheSE primer; Brush & Bond; Clearfil Protect Bond primer; iBond; One-up Bond F; OptiBond Solo Plus primer; Tyrian SPE primer; Unifil Bond primer and Xeno III). Conditioners were applied to IN and GR enamel surfaces, according to the manufacturer's instructions. Specimens etched with phosphoric acids were washed with water, while the surfaces treated with SES were submitted to alternate rinsing with alcohol and acetone. The specimens were dried, sputter-coated and examined under a scanning electron microscope. Results: For both IN and GR enamel surfaces, the EP of 34 and 35% FA was deeper and more homogeneous in comparison to EP of SES, except for Tyrian SPE. The acidic monomer action of self-etching systems was more effective on GR enamel. Conclusion: Most of the SES are less aggressive than phosphoric acid etchants and their etching effects were reduced on intact enamel surfaces. Uniterms: Dental acid etching; Dental enamel; Electron microscopy. PMID:19089243

  9. Spectrally enhanced image resolution of tooth enamel surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Liang; Nelson, Leonard Y.; Berg, Joel H.; Seibel, Eric J.

    2012-01-01

    Short-wavelength 405 nm laser illumination of surface dental enamel using an ultrathin scanning fiber endoscope (SFE) produced enhanced detail of dental topography. The surfaces of human extracted teeth and artificial erosions were imaged with 405 nm, 444 nm, 532 nm, or 635 nm illumination lasers. The obtained images were then processed offline to compensate for any differences in the illumination beam diameters between the different lasers. Scattering and absorption coefficients for a Monte Carlo model of light propagation in dental enamel for 405 nm were scaled from published data at 532 nm and 633 nm. The value of the scattering coefficient used in the model was scaled from the coefficients at 532 nm and 633 nm by the inverse third power of wavelength. Simulations showed that the penetration depth of short-wavelength illumination is localized close to the enamel surface, while long-wavelength illumination travels much further and is backscattered from greater depths. Therefore, images obtained using short wavelength laser are not contaminated by the superposition of light reflected from enamel tissue at greater depths. Hence, the SFE with short-wavelength illumination may make it possible to visualize surface manifestations of phenomena such as demineralization, thus better aiding the clinician in the detection of early caries.

  10. Protostylid expression at the enamel-dentine junction and enamel surface of mandibular molars of Paranthropus robustus and Australopithecus africanus.

    PubMed

    Skinner, Matthew M; Wood, Bernard A; Hublin, Jean-Jacques

    2009-01-01

    Distinctive expressions and incidences of discrete dental traits at the outer enamel surface (OES) contribute to the diagnoses of many early hominin taxa. Examination of the enamel-dentine junction (EDJ), imaged non-destructively using micro-computed tomography, has elucidated the morphological development of dental traits and improved interpretations of their variability within and among taxa. The OES expressions of one of these dental traits, the protostylid, have been found to differ among African Plio-Pleistocene fossil hominin taxa. In this study protostylid expression is examined at the OES and at the EDJ of Paranthropus robustus (n=23) and Australopithecus africanus (n=28) mandibular molars, with the goals of incorporating EDJ morphology into the definition of the protostylid and assessing the relative contribution of the EDJ and enamel cap to its expression in these taxa. The results provide evidence (a) of statistically significant taxon-specific patterns of protostylid morphology at the EDJ that are not evident at the OES; (b) that in P. robustus, thick enamel reduces the morphological correspondence between the form of the protostylid seen at the EDJ and the OES, and (c) that if EDJ images can be obtained, then the protostylid retains its taxonomic value even in worn teeth. PMID:18986683

  11. Further morphological evidence on South African earliest Homo lower postcanine dentition: Enamel thickness and enamel dentine junction.

    PubMed

    Pan, Lei; Dumoncel, Jean; de Beer, Frikkie; Hoffman, Jakobus; Thackeray, John Francis; Duployer, Benjamin; Tenailleau, Christophe; Braga, José

    2016-07-01

    The appearance of the earliest members of the genus Homo in South Africa represents a key event in human evolution. Although enamel thickness and enamel dentine junction (EDJ) morphology preserve important information about hominin systematics and dietary adaptation, these features have not been sufficiently studied with regard to early Homo. We used micro-CT to compare enamel thickness and EDJ morphology among the mandibular postcanine dentitions of South African early hominins (N = 30) and extant Homo sapiens (N = 26), with special reference to early members of the genus Homo. We found that South African early Homo shows a similar enamel thickness distribution pattern to modern humans, although three-dimensional average and relative enamel thicknesses do not distinguish australopiths, early Homo, and modern humans particularly well. Based on enamel thickness distributions, our study suggests that a dietary shift occurred between australopiths and the origin of the Homo lineage. We also observed that South African early Homo postcanine EDJ combined primitive traits seen in australopith molars with derived features observed in modern human premolars. Our results confirm that some dental morphological patterns in later Homo actually occurred early in the Homo lineage, and highlight the taxonomic value of premolar EDJ morphology in hominin species. PMID:27343773

  12. The enamel protein amelotin is a promoter of hydroxyapatite mineralization.

    PubMed

    Abbarin, Nastaran; San Miguel, Symone; Holcroft, James; Iwasaki, Kengo; Ganss, Bernhard

    2015-05-01

    Amelotin (AMTN) is a recently discovered protein that is specifically expressed during the maturation stage of dental enamel formation. It is localized at the interface between the enamel surface and the apical surface of ameloblasts. AMTN knock-out mice have hypomineralized enamel, whereas transgenic mice overexpressing AMTN have a compact but disorganized enamel hydroxyapatite (HA) microstructure, indicating a possible involvement of AMTN in regulating HA mineralization directly. In this study, we demonstrated that recombinant human (rh) AMTN dissolved in a metastable buffer system, based on light scattering measurements, promotes HA precipitation. The mineral precipitates were characterized by scanning and transmission electron microscopy and electron diffraction. Colloidal gold immunolabeling of AMTN in the mineral deposits showed that protein molecules were associated with HA crystals. The binding affinity of rh-AMTN to HA was found to be comparable to that of amelogenin, the major protein of the forming enamel matrix. Overexpression of AMTN in mouse calvaria cells also increased the formation of calcium deposits in the culture medium. Overexpression of AMTN during the secretory stage of enamel formation in vivo resulted in rapid and uncontrolled enamel mineralization. Site-specific mutagenesis of the potential serine phosphorylation motif SSEEL reduced the in vitro mineral precipitation to less than 25%, revealing that this motif is important for the HA mineralizing function of the protein. A synthetic short peptide containing the SSEEL motif was only able to facilitate mineralization in its phosphorylated form ((P)S(P) SEEL), indicating that this motif is necessary but not sufficient for the mineralizing properties of AMTN. These findings demonstrate that AMTN has a direct influence on biomineralization by promoting HA mineralization and suggest a critical role for AMTN in the formation of the compact aprismatic enamel surface layer during the maturation

  13. Enamel Pearls Implications on Periodontal Disease

    PubMed Central

    Zenóbio, Elton Gonçalves; Vieira, Thaís Ribeiral; Bustamante, Roberta Paula Colen; Gomes, Hayder Egg; Shibli, Jamil Awad; Soares, Rodrigo Villamarin

    2015-01-01

    Dental anatomy is quite complex and diverse factors must be taken into account in its analysis. Teeth with anatomical variations present an increase in the rate of severity periodontal tissue destruction and therefore a higher risk of developing periodontal disease. In this context, this paper reviews the literature regarding enamel pearls and their implications in the development of severe localized periodontal disease as well as in the prognosis of periodontal therapy. Radiographic examination of a patient complaining of pain in the right side of the mandible revealed the presence of a radiopaque structure around the cervical region of lower right first premolar. Periodontal examination revealed extensive bone loss since probing depths ranged from 7.0 mm to 9.0 mm and additionally intense bleeding and suppuration. Surgical exploration detected the presence of an enamel pearl, which was removed. Assessment of the remaining supporting tissues led to the extraction of tooth 44. Local factors such as enamel pearls can lead to inadequate removal of the subgingival biofilm, thus favoring the establishment and progression of periodontal diseases. PMID:26491574

  14. Kinetics of enamel demineralization in vitro.

    PubMed

    Margolis, H C; Zhang, Y P; Lee, C Y; Kent, R L; Moreno, E C

    1999-07-01

    Previously, we reported that the rate (R) of hydroxyapatite dissolution in acetic, lactic, and phosphoric acid solutions is a function of the degree of saturation with respect to the dissolving mineral, DS (defined as the ratio of the mean ionic activity product for hydroxyapatite [Ca5OH(PO4)3] in solution to its solubility product constant), and the sum of the acid activities (sumBiH) in solution: R = K(1-DS)m(sumBiH)n. The present study was undertaken to explore the general validity of this model in describing the kinetics of enamel demineralization. Thin sections of human enamel were exposed to partially saturated 0.1 mol/L lactic acid solutions, at two different DS levels, and at pH values of 4.3 to 6.0. Thin sections of human enamel were also exposed to solutions with four different concentrations of acetic and lactic acids (pH 4.3) with three different DS values and, at one DS value, to solutions of propionic acid. Mineral loss was monitored by quantitative microradiography. In solutions with pH values of 4.3 and 5.0, "lesions" were formed with well-defined surface layers, whereas, in solutions with pH 6.0, "lesions" were produced with no apparent surface layers. The formation of relatively intact surface layers was consistent with predicted phase transformations. Rates of mineral loss were found to be inversely proportional to both the degree of saturation with respect to enamel mineral, DS(En), and the pH of the solution and increased with increased activities of each organic acid, consistent with the proposed model. However, at the same DS(En) and acid activity, rates of demineralization were the same in the acetic and propionic acid solutions, whereas rates of demineralization in lactic acid were greater. It is suggested that specific interactions of acid species with enamel mineral may modify the rate of enamel demineralization. These in vitro findings suggest that relatively small differences in DS(En) values found in plaque fluid may result in very

  15. Enamel renal syndrome with associated amelogenesis imperfecta, nephrolithiasis, and hypocitraturia: A case report.

    PubMed

    Bhesania, Dhvani; Arora, Ankit; Kapoor, Sonali

    2015-09-01

    Numerous cases of enamel renal syndrome have been previously reported. Various terms, such as enamel renal syndrome, amelogenesis imperfecta and gingival fibromatosis syndrome, and enamel-renal-gingival syndrome, have been used for patients presenting with the dental phenotype characteristic of this condition, nephrocalcinosis or nephrolithiasis, and gingival findings. This report describes a case of amelogenesis imperfecta of the enamel agenesis variety with nephrolithiasis in a 21-year-old male patient who complained of small teeth. The imaging modalities employed were conventional radiography, cone-beam computed tomography, and renal sonography. Such cases are first encountered by dentists, as other organ or metabolic diseases are generally hidden. Hence, cases of amelogenesis imperfecta should be subjected to advanced diagnostic modalities, incorporating both dental and medical criteria, in order to facilitate comprehensive long-term management. PMID:26389061

  16. Drugs that promote dental caries.

    PubMed

    2015-02-01

    Dental caries result from erosion of tooth enamel or cementum by acidic substances produced by bacteria found in dental plaque. Caries can lead to pulp necrosis and tooth loss. Risk factors include certain dietary habits, poor oral hygiene, and dry mouth. Diabetes and Sjogren's syndrome can also promote dental caries. Psychotropic substances such as cocaine, methamphetamine, heroin and cannabis can promote dental caries. Many medicinal drugs facilitate the formation of dental caries, through various mechanisms; they include formulations with a high sugar content; drugs that cause dry mouth (especially antimuscarinics); drugs that lower the buccal pH (inhaled powders, etc.); and drugs that cause demineralisation (tetracyclines, etc.). In practice, patients (and parents) should be informed that some drugs can increase the risk of dental caries. They should be encouraged to adapt and reinforce dental hygiene, and advised to visit a dentist regularly. PMID:25802916

  17. Nephrocalcinosis associated with continuous enamel hypoplasia and severe alveolar bone loss: a case report and literature review.

    PubMed

    Ashkenazi, Malka; Rafe, Zvi; Sarnat, Haim; Levin, Liran

    2014-01-01

    Enamel-renal syndrome (ERS) is a rare manifestation of nephrocalcinosis that has been associated with generalized enamel hypoplasia. The purpose of this paper was to describe, for the first time, the association of enamel-renal syndrome with severe localized periodontal bone loss. A 13-year-old boy presented with: generalized hypoplastic enamel; intrapulpal calcifications; retention of primary teeth; delayed eruption of permanent teeth; enlarged dental-follicles; misshaped roots of permanent teeth; gingival overgrowth; severe localized alveolar bone loss; and severe malocclusion. His parents were first cousins, suggesting autosomal recessive inheritance. Further studies are necessary to clarify whether the etiology of the oral disturbances relates to the genetic defect in the dental tissue or to the continuous metabolic distress associated with renal dysfunction. Nevertheless, since nephrocalcinosis is often asymptomatic, dentists should refer children with generalized enamel hypoplasia or/and multiple intrapulpal calcifications to nephrologists. PMID:24960394

  18. Mapping residual organics and carbonate at grain boundaries and the amorphous interphase in mouse incisor enamel

    PubMed Central

    Gordon, Lyle M.; Joester, Derk

    2015-01-01

    Dental enamel has evolved to resist the most grueling conditions of mechanical stress, fatigue, and wear. Adding insult to injury, it is exposed to the frequently corrosive environment of the oral cavity. While its hierarchical structure is unrivaled in its mechanical resilience, heterogeneity in the distribution of magnesium ions and the presence of Mg-substituted amorphous calcium phosphate (Mg-ACP) as an intergranular phase have recently been shown to increase the susceptibility of mouse enamel to acid attack. Herein we investigate the distribution of two important constituents of enamel, residual organic matter and inorganic carbonate. We find that organics, carbonate, and possibly water show distinct distribution patterns in the mouse enamel crystallites, at simple grain boundaries, and in the amorphous interphase at multiple grain boundaries. This has implications for the resistance to acid corrosion, mechanical properties, and the mechanism by which enamel crystals grow during amelogenesis. PMID:25852562

  19. Remineralization of initial enamel caries in vitro using a novel peptide based on amelogenin

    NASA Astrophysics Data System (ADS)

    Li, Danxue; Lv, Xueping; Tu, Huanxin; Zhou, Xuedong; Yu, Haiyang; Zhang, Linglin

    2015-09-01

    Dental caries is the most common oral disease with high incidence, widely spread and can seriously affect the health of oral cavity and the whole body. Current caries prevention measures such as fluoride treatment, antimicrobial agents, and traditional Chinese herbal, have limitations to some extent. Here we design and synthesize a novel peptide based on the amelogenin, and assess its ability to promote the remineralization of initial enamel caries lesions. We used enamel blocks to form initial lesions, and then subjected to 12-day pH cycling in the presence of peptide, NaF and HEPES buffer. Enamel treated with peptide or NaF had shallower, narrower lesions, thicker remineralized surfaces and less mineral loss than enamel treated with HEPES. This peptide can promote the remineralization of initial enamel caries and inhibit the progress of caries. It is a promising anti-caries agent with various research prospects and practical application value.

  20. Mapping residual organics and carbonate at grain boundaries and the amorphous interphase in mouse incisor enamel.

    PubMed

    Gordon, Lyle M; Joester, Derk

    2015-01-01

    Dental enamel has evolved to resist the most grueling conditions of mechanical stress, fatigue, and wear. Adding insult to injury, it is exposed to the frequently corrosive environment of the oral cavity. While its hierarchical structure is unrivaled in its mechanical resilience, heterogeneity in the distribution of magnesium ions and the presence of Mg-substituted amorphous calcium phosphate (Mg-ACP) as an intergranular phase have recently been shown to increase the susceptibility of mouse enamel to acid attack. Herein we investigate the distribution of two important constituents of enamel, residual organic matter and inorganic carbonate. We find that organics, carbonate, and possibly water show distinct distribution patterns in the mouse enamel crystallites, at simple grain boundaries, and in the amorphous interphase at multiple grain boundaries. This has implications for the resistance to acid corrosion, mechanical properties, and the mechanism by which enamel crystals grow during amelogenesis. PMID:25852562

  1. Inhibition of enamel erosion by stannous fluoride containing rinsing solutions.

    PubMed

    Rakhmatullina, Ekaterina; Beyeler, Barbara; Lussi, Adrian

    2013-01-01

    This in vitro study investigated the erosion-inhibiting properties of dental rinses during erosion in the presence of the salivary pellicle. The erosion inhibition by a Sn/F containing dental rinse (800 ppm Sn2+, 500 ppm F –, pH = 4.5) was compared with a fluoridated solution (500 ppm F –, pH = 4.5) and water(control). Calcium release and enamel softening were significantly reduced among enamel samples exposed to the Sn/F rinse (group SF)compared to those treated with the fluoride solution (group F) and the control (p 0.05). SEM showed slightly etched enamel interfaces in group SF, whereas the erosion was more pronounced in group F and even more severe in the control group. In conclusion, the Sn/F combination provided the best inhibition of erosion among tested solutions. This study demonstrates the application of different analytical tools for comparative erosion quantification.A strong correlation (r2 ≥ 0.783) was shown between calcium release and enamel softening during demineralization. PMID:23781557

  2. Fluorescence of dental porcelain.

    PubMed

    Monsénégo, G; Burdairon, G; Clerjaud, B

    1993-01-01

    This study of the fluorescence of natural enamel and of dental ceramics shows the fluorescence of ceramics not containing rare earths decreases when the color saturation increases; the fluorescence of samples of the same shade guide are not homogenous; some guides show a strong green fluorescence; and two shade guides of the same origin can present completely different fluorescence. The cementing medium can affect the fluorescence of a ceramic prosthesis. PMID:8455155

  3. Increased enamel hypoplasia and very low birthweight infants.

    PubMed

    Nelson, S; Albert, J M; Geng, C; Curtan, S; Lang, K; Miadich, S; Heima, M; Malik, A; Ferretti, G; Eggertsson, H; Slayton, R L; Milgrom, P

    2013-09-01

    Birth cohort studies of developmental defects of enamel (DDE) and early childhood caries (ECC) in very low birthweight (VLBW) and normal birthweight (NBW) infants are rare. In this birth cohort of 234 VLBW and 234 NBW infants, we report the incidence of ECC and DDE at 8 and 18-20 mos of corrected age. Infant medical and maternal socio-demographic data were abstracted from medical records at birth. Dental assessments for ECC and DDE (enamel hypoplasia, demarcated and diffuse opacities) were completed at 8 and 18-20 mos. The incidence of hypoplasia was significantly higher in VLBW compared with NBW infants (8 mos, 19% vs. 2%; 18 mos, 31% vs. 8%). The incidence of ECC (International Caries Detection and Assessment System: ICDAS ≥ 2) was 1.4% (8 mos) and 12% (18-20 mos) and was similar between the VLBW and NBW groups. At both ages, using a beta-binomial regression model to control for potential confounders (maternal and infant characteristics), we found increased risk for enamel hypoplasia among the VLBW infants compared with the NBW infants. African Americans had a lower risk for enamel hypoplasia at 18-20 mos. The VLBW infants should be monitored for ECC due to the presence of enamel hypoplasia. PMID:23857641

  4. Enzyme replacement prevents enamel defects in hypophosphatasia mice.

    PubMed

    Yadav, Manisha C; de Oliveira, Rodrigo Cardoso; Foster, Brian L; Fong, Hanson; Cory, Esther; Narisawa, Sonoko; Sah, Robert L; Somerman, Martha; Whyte, Michael P; Millán, José Luis

    2012-08-01

    Hypophosphatasia (HPP) is the inborn error of metabolism characterized by deficiency of alkaline phosphatase activity, leading to rickets or osteomalacia and to dental defects. HPP occurs from loss-of-function mutations within the gene that encodes the tissue-nonspecific isozyme of alkaline phosphatase (TNAP). TNAP knockout (Alpl(-/-), aka Akp2(-/-)) mice closely phenocopy infantile HPP, including the rickets, vitamin B6-responsive seizures, improper dentin mineralization, and lack of acellular cementum. Here, we report that lack of TNAP in Alpl(-/-) mice also causes severe enamel defects, which are preventable by enzyme replacement with mineral-targeted TNAP (ENB-0040). Immunohistochemistry was used to map the spatiotemporal expression of TNAP in the tissues of the developing enamel organ of healthy mouse molars and incisors. We found strong, stage-specific expression of TNAP in ameloblasts. In the Alpl(-/-) mice, histological, µCT, and scanning electron microscopy analysis showed reduced mineralization and disrupted organization of the rods and inter-rod structures in enamel of both the molars and incisors. All of these abnormalities were prevented in mice receiving from birth daily subcutaneous injections of mineral-targeting, human TNAP at 8.2 mg/kg/day for up to 44 days. These data reveal an important role for TNAP in enamel mineralization and demonstrate the efficacy of mineral-targeted TNAP to prevent enamel defects in HPP. PMID:22461224

  5. Near-surface structural examination of human tooth enamel subject to in vitro demineralization and remineralization

    NASA Astrophysics Data System (ADS)

    Gaines, Carmen Veronica

    The early stages of chemical tooth decay are governed by dynamic processes of demineralization and remineralization of dental enamel that initiates along the surface of the tooth. Conventional diagnostic techniques lack the spatial resolution required to analyze near-surface structural changes in enamel at the submicron level. In this study, slabs of highly-polished, decay-free human enamel were subjected to 0.12M EDTA and buffered lactic acid demineralizing agents and MI Paste(TM) and calcifying (0.1 ppm F) remineralizing treatments in vitro. Grazing incidence x-ray diffraction (GIXD), a technique typically used for thin film analysis, provided depth profiles of crystallinity changes in surface enamel with a resolution better than 100 nm. In conjunction with nanoindentation, a technique gaining acceptance as a means of examining the mechanical properties of sound enamel, these results were corroborated with well-established microscopy and Raman techniques to assess the nanohardness, morphologies and chemical nature of treated enamel. Interestingly, the average crystallite size of surface enamel along its c-axis dimension increased by nearly 40% after a 60 min EDTA treatment as detected by GIXD. This result was in direct contrast to the obvious surface degradation observed by microscopic and confocal Raman imaging. A decrease in nanohardness from 4.86 +/- 0.44 GPa to 0.28 +/- 0.10 GPa was observed. Collective results suggest that mineral dissolution characteristics evident on the micron scale may not be fully translated to the nanoscale in assessing the integrity of chemically-modified tooth enamel. While an intuitive decrease in enamel crystallinity was observed with buffered lactic acid-treated samples, demineralization was too slow to adequately quantify the enamel property changes seen. MI Paste(TM) treatment of EDTA-demineralized enamel showed preferential growth along the a-axis direction. Calcifying solution treatments of both demineralized sample types

  6. Developmental and Post-Eruptive Defects in Molar Enamel of Free-Ranging Eastern Grey Kangaroos (Macropus giganteus) Exposed to High Environmental Levels of Fluoride

    PubMed Central

    Kierdorf, Uwe; Death, Clare; Hufschmid, Jasmin; Witzel, Carsten; Kierdorf, Horst

    2016-01-01

    Dental fluorosis has recently been diagnosed in wild marsupials inhabiting a high-fluoride area in Victoria, Australia. Information on the histopathology of fluorotic marsupial enamel has thus far not been available. This study analyzed the developmental and post-eruptive defects in fluorotic molar enamel of eastern grey kangaroos (Macropus giganteus) from the same high-fluoride area using light microscopy and backscattered electron imaging in the scanning electron microscope. The fluorotic enamel exhibited a brownish to blackish discolouration due to post-eruptive infiltration of stains from the oral cavity and was less resistant to wear than normally mineralized enamel of kangaroos from low-fluoride areas. Developmental defects of enamel included enamel hypoplasia and a pronounced hypomineralization of the outer (sub-surface) enamel underneath a thin rim of well-mineralized surface enamel. While the hypoplastic defects denote a disturbance of ameloblast function during the secretory stage of amelogenesis, the hypomineralization is attributed to an impairment of enamel maturation. In addition to hypoplastic defects, the fluorotic molars also exhibited numerous post-eruptive enamel defects due to the flaking-off of portions of the outer, hypomineralized enamel layer during mastication. The macroscopic and histopathological lesions in fluorotic enamel of M. giganteus match those previously described for placental mammals. It is therefore concluded that there exist no principal differences in the pathogenic mechanisms of dental fluorosis between marsupial and placental mammals. The regular occurrence of hypomineralized, opaque outer enamel in the teeth of M. giganteus and other macropodids must be considered in the differential diagnosis of dental fluorosis in these species. PMID:26895178

  7. Developmental and Post-Eruptive Defects in Molar Enamel of Free-Ranging Eastern Grey Kangaroos (Macropus giganteus) Exposed to High Environmental Levels of Fluoride.

    PubMed

    Kierdorf, Uwe; Death, Clare; Hufschmid, Jasmin; Witzel, Carsten; Kierdorf, Horst

    2016-01-01

    Dental fluorosis has recently been diagnosed in wild marsupials inhabiting a high-fluoride area in Victoria, Australia. Information on the histopathology of fluorotic marsupial enamel has thus far not been available. This study analyzed the developmental and post-eruptive defects in fluorotic molar enamel of eastern grey kangaroos (Macropus giganteus) from the same high-fluoride area using light microscopy and backscattered electron imaging in the scanning electron microscope. The fluorotic enamel exhibited a brownish to blackish discolouration due to post-eruptive infiltration of stains from the oral cavity and was less resistant to wear than normally mineralized enamel of kangaroos from low-fluoride areas. Developmental defects of enamel included enamel hypoplasia and a pronounced hypomineralization of the outer (sub-surface) enamel underneath a thin rim of well-mineralized surface enamel. While the hypoplastic defects denote a disturbance of ameloblast function during the secretory stage of amelogenesis, the hypomineralization is attributed to an impairment of enamel maturation. In addition to hypoplastic defects, the fluorotic molars also exhibited numerous post-eruptive enamel defects due to the flaking-off of portions of the outer, hypomineralized enamel layer during mastication. The macroscopic and histopathological lesions in fluorotic enamel of M. giganteus match those previously described for placental mammals. It is therefore concluded that there exist no principal differences in the pathogenic mechanisms of dental fluorosis between marsupial and placental mammals. The regular occurrence of hypomineralized, opaque outer enamel in the teeth of M. giganteus and other macropodids must be considered in the differential diagnosis of dental fluorosis in these species. PMID:26895178

  8. Epithelial-specific knockout of the Rac1 gene leads to enamel defects

    PubMed Central

    Huang, Zhan; Kim, Jieun; Lacruz, Rodrigo; Bringas, Pablo; Kaartinen, Vesa M.; Snead, Malcolm L.

    2015-01-01

    Rac1 encodes a 21kDa GTP-binding protein belonging to the RAS superfamily. RAS members play important roles in controlling focal adhesion complex formation and cytoskeleton contraction; activities with consequences to cell growth, adhesion, migration, and differentiation. To examine the role(s) played by Rac1 protein in cell-to-matrix interaction and in enamel matrix biomineralization we used the Cre/loxP binary recombination system to characterize enamel matrix proteins expression and enamel formation in Rac1 knockout mice. Mating between mice bearing the floxed Rac1 allele with mice bearing a keratin14-Cre transgene generate animals in which Rac1 is absent from epithelial organs. The enamel of Rac1 conditional knockout mouse was characterized by computerized tomography (microCT), light microscopy, histochemistry, and back-scatter electron microscopy. Enamel matrix protein expression was analyzed by Western blotting. Major findings showed that the Tomes’ processes of Rac1−/− ameloblasts loose contact with the forming enamel matrix in un-erupted teeth. The abundance of amelogenin and ameloblastin was reduced in the Rac1−/− ameloblasts. After eruption, the enamel from the Rac1−/− mice displayed severe structural defects with the complete loss of enamel. These results support an essential role for Rac1 function in the dental epithelium involving cell-matrix interaction and matrix biomineralization. PMID:22243243

  9. A Descriptive in vitro Electron Microscopic Study of Acidic Fluoride-Treated Enamel: Potential Anti-Erosion Effects.

    PubMed

    Hjortsjö, Carl; Young, Alix; Kiesow, Andreas; Cismak, Andreas; Berthold, Lutz; Petzold, Matthias

    2015-01-01

    This study aimed to investigate the surface zones of acidic fluoride-treated enamel. Human teeth were each divided into three or four enamel specimens that were treated for 10 min with solutions of 0.2 and 0.4% HF (pH 3.09 and 2.94), 1.74% SnF2 (pH 2.9), 0.68% TiF4 (pH 1.6) and 0.84% NaF (pH 4.5). Untreated specimens functioned as negative controls. The microstructure and elemental composition of the surface zones were studied by scanning electron microscopy/energy-dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and nanospot-EDX following cross-sectional preparation using focused ion beam technology. TEM/EDX analyses of NaF-treated specimens showed a 500-nm-thick closed surface film containing 20-40 at% (atomic percent) F. HF-treated specimens had a distinct surface film 200-600 nm thick (dense, not globular) containing 45-47 at% F. TiF4-treated specimens had a surface film of 200-300 nm in thickness containing 8-11 at% Ti but no detectable fluoride. SnF2-treated specimens had a modified surface enamel layer varying in thickness from 200 to 800 nm with an inhomogeneous distribution of Sn. Local spots were detected with as high as 8 at% Sn (30 wt%, weight percent). The results suggest that the reaction mechanisms of SnF2 and TiF4 solutions with dental enamel differ from those occurring after enamel exposure to acidulated NaF and HF solutions. While the HF and NaF treatments resulted in the formation of CaF2-like material as shown by EDX, no significant surface fluoridation was found for SnF2 and TiF4 solutions within the TEM/EDX detection limits. These results suggest that the erosion-protective mechanisms of these latter compounds probably relate more to the formation of hardly soluble and acid-resistant reaction surface films and less to surface fluoride incorporation. PMID:26536617

  10. Differential diagnosis of dental fluorosis made by undergraduate dental students

    PubMed Central

    Rigo, Lilian; Lodi, Leodinei; Garbin, Raíssa Rigo

    2015-01-01

    ABSTRACT Objective To check knowledge of undergraduate dental students to make diagnosis of dental fluorosis with varying degrees of severity and choose its appropriate treatment. Methods Data were collected using a semi-structured questionnaire addressing knowledge of undergraduates based on ten images of mouths presenting enamel changes. Results Only three images were correctly diagnosed by most undergraduates; the major difficulty was in establishing dental fluorosis severity degree. Conclusion Despite much information about fluorosis conveyed during the Dentistry training, as defined in the course syllabus, a significant part of the students was not able to differentiate it from other lesions; they did not demonstrate expertise as to defining severity of fluorosis and indications for treatment, and could not make the correct diagnosis of enamel surface changes. PMID:26761552

  11. Store-operated Ca2+ Entry Modulates the Expression of Enamel Genes.

    PubMed

    Nurbaeva, M K; Eckstein, M; Snead, M L; Feske, S; Lacruz, R S

    2015-10-01

    Dental enamel formation is an intricate process tightly regulated by ameloblast cells. The correct spatiotemporal patterning of enamel matrix protein (EMP) expression is fundamental to orchestrate the formation of enamel crystals, which depend on a robust supply of Ca2+. In the extracellular milieu, Ca2+ -EMP interactions occur at different levels. Despite its recognized role in enamel development, the molecular machinery involved in Ca2+ homeostasis in ameloblasts remains poorly understood. A common mechanism for Ca2+ influx is store-operated Ca2+ entry (SOCE). We evaluated the possibility that Ca2+ influx in enamel cells might be mediated by SOCE and the Ca2+ release-activated Ca2+ (CRAC) channel, the prototypical SOCE channel. Using ameloblast-like LS8 cells, we demonstrate that these cells express Ca2+ -handling molecules and mediate Ca2+ influx through SOCE. As a rise in the cytosolic Ca2+ concentration is a versatile signal that can modulate gene expression, we assessed whether SOCE in enamel cells had any effect on the expression of EMPs. Our results demonstrate that stimulating LS8 cells or murine primary enamel organ cells with thapsigargin to activate SOCE leads to increased expression of Amelx, Ambn, Enam, Mmp20. This effect is reversed when cells are treated with a CRAC channel inhibitor. These data indicate that Ca2+ influx in LS8 cells and enamel organ cells is mediated by CRAC channels and that Ca2+ signals enhance the expression of EMPs. Ca2+ plays an important role not only in mineralizing dental enamel but also in regulating the expression of EMPs. PMID:26232387

  12. CO₂ laser emission modes to control enamel erosion.

    PubMed

    Scatolin, Renata Siqueira; Alonso-Filho, Fernando Luiz; Galo, Rodrigo; Rios, Daniela; Borsatto, Maria Cristina; Corona, Silmara Aparecida Milori

    2015-08-01

    Considering the importance and prevalence of dental erosion, the aim of this in vitro study was to evaluate the influence of different modes of pulse emission of CO2 laser associated or not to acidulated phosphate fluoride (APF) 1.23% gel, in controlling enamel erosion by profilometry. Ninety-six fragments of bovine enamel were flattened and polished, and the specimens were subjected to initial erosive challenge with hydrochloric acid (pH = 2). Specimens were randomly assigned according to surface treatment: APF 1.23% gel and gel without fluoride (control), and subdivided according to the modes of pulse CO2 laser irradiation: no irradiation (control), continuous, ultrapulse, and repeated pulse (n = 12). After surface treatment, further erosive challenges were performed for 5 days, 4 × 2 min/day. Enamel structure loss was quantitatively determined by a profilometer, after surface treatment and after 5 days of erosive challenges. Two-away ANOVA revealed a significant difference between the pulse emission mode of the CO2 laser and the presence of fluoride (P ≤ 0.05). The Duncan's test showed that CO2 laser irradiation in continuous mode and the specimens only received fluoride, promoted lower enamel loss than that other treatments. A lower dissolution of the enamel prisms was observed when it was irradiated with CO2 laser in continuous mode compared other groups. It can be concluded that CO2 laser irradiation in continuous mode was the most effective to control the enamel structure loss submitted to erosive challenges with hydrochloric acid. PMID:25988247

  13. Enamel Ultrastructure in Fossil Cetaceans (Cetacea: Archaeoceti and Odontoceti)

    PubMed Central

    Loch, Carolina; Fordyce, R. Ewan

    2015-01-01

    The transition from terrestrial ancestry to a fully pelagic life profoundly altered the body systems of cetaceans, with extreme morphological changes in the skull and feeding apparatus. The Oligocene Epoch was a crucial time in the evolution of cetaceans when the ancestors of modern whales and dolphins (Neoceti) underwent major diversification, but details of dental structure and evolution are poorly known for the archaeocete-neocete transition. We report the morphology of teeth and ultrastructure of enamel in archaeocetes, and fossil platanistoids and delphinoids, ranging from late Oligocene (Waitaki Valley, New Zealand) to Pliocene (Caldera, Chile). Teeth were embedded in epoxy resin, sectioned in cross and longitudinal planes, polished, etched, and coated with gold palladium for scanning electron microscopy (SEM) observation. SEM images showed that in archaeocetes, squalodontids and Prosqualodon (taxa with heterodont and nonpolydont/limited polydont teeth), the inner enamel was organized in Hunter-Schreger bands (HSB) with an outer layer of radial enamel. This is a common pattern in most large-bodied mammals and it is regarded as a biomechanical adaptation related to food processing and crack resistance. Fossil Otekaikea sp. and delphinoids, which were polydont and homodont, showed a simpler structure, with inner radial and outer prismless enamel. Radial enamel is regarded as more wear-resistant and has been retained in several mammalian taxa in which opposing tooth surfaces slide over each other. These observations suggest that the transition from a heterodont and nonpolydont/limited polydont dentition in archaeocetes and early odontocetes, to homodont and polydont teeth in crownward odontocetes, was also linked to a marked simplification in the enamel Schmelzmuster. These patterns probably reflect functional shifts in food processing from shear-and-mastication in archaeocetes and early odontocetes, to pierce-and-grasp occlusion in crownward odontocetes, with

  14. Enamel ultrastructure in fossil cetaceans (Cetacea: Archaeoceti and Odontoceti).

    PubMed

    Loch, Carolina; Kieser, Jules A; Fordyce, R Ewan

    2015-01-01

    The transition from terrestrial ancestry to a fully pelagic life profoundly altered the body systems of cetaceans, with extreme morphological changes in the skull and feeding apparatus. The Oligocene Epoch was a crucial time in the evolution of cetaceans when the ancestors of modern whales and dolphins (Neoceti) underwent major diversification, but details of dental structure and evolution are poorly known for the archaeocete-neocete transition. We report the morphology of teeth and ultrastructure of enamel in archaeocetes, and fossil platanistoids and delphinoids, ranging from late Oligocene (Waitaki Valley, New Zealand) to Pliocene (Caldera, Chile). Teeth were embedded in epoxy resin, sectioned in cross and longitudinal planes, polished, etched, and coated with gold palladium for scanning electron microscopy (SEM) observation. SEM images showed that in archaeocetes, squalodontids and Prosqualodon (taxa with heterodont and nonpolydont/limited polydont teeth), the inner enamel was organized in Hunter-Schreger bands (HSB) with an outer layer of radial enamel. This is a common pattern in most large-bodied mammals and it is regarded as a biomechanical adaptation related to food processing and crack resistance. Fossil Otekaikea sp. and delphinoids, which were polydont and homodont, showed a simpler structure, with inner radial and outer prismless enamel. Radial enamel is regarded as more wear-resistant and has been retained in several mammalian taxa in which opposing tooth surfaces slide over each other. These observations suggest that the transition from a heterodont and nonpolydont/limited polydont dentition in archaeocetes and early odontocetes, to homodont and polydont teeth in crownward odontocetes, was also linked to a marked simplification in the enamel Schmelzmuster. These patterns probably reflect functional shifts in food processing from shear-and-mastication in archaeocetes and early odontocetes, to pierce-and-grasp occlusion in crownward odontocetes, with

  15. Clinical assessment of enamel wear caused by monolithic zirconia crowns.

    PubMed

    Stober, T; Bermejo, J L; Schwindling, F S; Schmitter, M

    2016-08-01

    The purpose of this study was to measure enamel wear caused by antagonistic monolithic zirconia crowns and to compare this with enamel wear caused by contralateral natural antagonists. Twenty monolithic zirconia full molar crowns were placed in 20 patients. Patients with high activity of the masseter muscle at night (bruxism) were excluded. For analysis of wear, vinylpolysiloxane impressions were prepared after crown incorporation and at 6-, 12-, and 24-month follow-up. Wear of the occlusal contact areas of the crowns, of their natural antagonists, and of two contralateral natural antagonists (control teeth) was measured by use of plaster replicas and a 3D laser-scanning device. Differences of wear between the zirconia crown antagonists and the control teeth were investigated by means of two-sided paired Student's t-tests and linear regression analysis. After 2 years, mean vertical loss was 46 μm for enamel opposed to zirconia, 19-26 μm for contralateral control teeth and 14 μm for zirconia crowns. Maximum vertical loss was 151 μm for enamel opposed to zirconia, 75-115 μm for control teeth and 60 μm for zirconia crowns. Statistical analysis revealed significant differences between wear of enamel by zirconia-opposed teeth and by control teeth. Gender, which significantly affected wear, was identified as a possible confounder. Monolithic zirconia crowns generated more wear of opposed enamel than did natural teeth. Because of the greater wear caused by other dental ceramics, the use of monolithic zirconia crowns may be justified. PMID:27198539

  16. Mechanical behavior of enamel rods under micro-compression.

    PubMed

    Yilmaz, Ezgi D; Schneider, Gerold A

    2016-10-01

    Exploring the structural strategies behind the optimized mechanical performance of hierarchical materials has been a focal point of extensive research over the past decades. Dental enamel is one such natural material, comprising a complicated hierarchical structure with a high level of mineral content. Bundles of hydroxyapatite nanofibers (level-1) Ø: 50nm form enamel rods (level-2) Ø: 5µm, which constitute bands (level-3) Ø: 50µm. While a number of studies in the last decade using advanced fracture mechanical methods have revealed an increasing trend in the fracture toughness of enamel with each additional level of hierarchy, there is still no general agreement on how hierarchical structuring affects the stiffness and strength of enamel. In this study, we identified the stiffness and strength values of the isolated rods (level-2) via micro-compression. The rods were tested in three different orientations with respect to the loading direction: parallel, perpendicular and oblique. The highest stress level withstood before catastrophic fracture was observed to be ~1500MPa in perpendicular orientation. In the oblique loading, the specimens failed by shearing and exhibited a damage-tolerant deformation behavior, which was attributed to the conjugation spots identified between the rods and interrod sheets. The elastic modulus was ~60GPa on average and similar in all orientations. The isotropy in stiffness was attributed to the mineral contacts residing between rods. This was verified by an analytical model derived for level-1 and extended over higher hierarchical levels. The experimental results obtained at level-2 were comparable to the compressive strength and stiffness values reported for level-1 and bulk enamel in the literature. In general, our results suggest that hierarchy has only a minor influence on the compressive properties of enamel. PMID:27415405

  17. Self-cleaning and antibiofouling enamel surface by slippery liquid-infused technique.

    PubMed

    Yin, JiaLi; Mei, May Lei; Li, QuanLi; Xia, Rong; Zhang, ZhiHong; Chu, Chun Hung

    2016-01-01

    We aimed to create a slippery liquid-infused enamel surface with antibiofouling property to prevent dental biofilm/plaque formation. First, a micro/nanoporous enamel surface was obtained by 37% phosphoric acid etching. The surface was then functionalized by hydrophobic low-surface energy heptadecafluoro-1,1,2,2-tetra- hydrodecyltrichlorosilane. Subsequent infusion of fluorocarbon lubricants (Fluorinert FC-70) into the polyfluoroalkyl-silanized rough surface resulted in an enamel surface with slippery liquid-infused porous surface (SLIPS). The results of water contact angle measurement, diffuse-reflectance Fourier transform infrared spectroscopy, and atomic force microscope confirmed that the SLIPS was successfully constructed on the enamel surface. The antibiofouling property of the SLIPS was evaluated by the adsorption of salivary protein of mucin and Streptococcus mutans in vitro, as well as dental biofilm formation using a rabbit model in vivo. The results showed that the SLIPS on the enamel surface significantly inhibited mucin adhesion and S. mutans biofilm formation in vitro, and inhibited dental plaque formation in vivo. PMID:27181424

  18. Self-cleaning and antibiofouling enamel surface by slippery liquid-infused technique

    NASA Astrophysics Data System (ADS)

    Yin, Jiali; Mei, May Lei; Li, Quanli; Xia, Rong; Zhang, Zhihong; Chu, Chun Hung

    2016-05-01

    We aimed to create a slippery liquid-infused enamel surface with antibiofouling property to prevent dental biofilm/plaque formation. First, a micro/nanoporous enamel surface was obtained by 37% phosphoric acid etching. The surface was then functionalized by hydrophobic low-surface energy heptadecafluoro-1,1,2,2-tetra- hydrodecyltrichlorosilane. Subsequent infusion of fluorocarbon lubricants (Fluorinert FC-70) into the polyfluoroalkyl-silanized rough surface resulted in an enamel surface with slippery liquid-infused porous surface (SLIPS). The results of water contact angle measurement, diffuse-reflectance Fourier transform infrared spectroscopy, and atomic force microscope confirmed that the SLIPS was successfully constructed on the enamel surface. The antibiofouling property of the SLIPS was evaluated by the adsorption of salivary protein of mucin and Streptococcus mutans in vitro, as well as dental biofilm formation using a rabbit model in vivo. The results showed that the SLIPS on the enamel surface significantly inhibited mucin adhesion and S. mutans biofilm formation in vitro, and inhibited dental plaque formation in vivo.

  19. p38α MAPK is required for tooth morphogenesis and enamel secretion.

    PubMed

    Greenblatt, Matthew B; Kim, Jung-Min; Oh, Hwanhee; Park, Kwang Hwan; Choo, Min-Kyung; Sano, Yasuyo; Tye, Coralee E; Skobe, Ziedonis; Davis, Roger J; Park, Jin Mo; Bei, Marianna; Glimcher, Laurie H; Shim, Jae-Hyuck

    2015-01-01

    An improved understanding of the molecular pathways that drive tooth morphogenesis and enamel secretion is needed to generate teeth from organ cultures for therapeutic implantation or to determine the pathogenesis of primary disorders of dentition (Abdollah, S., Macias-Silva, M., Tsukazaki, T., Hayashi, H., Attisano, L., and Wrana, J. L. (1997) J. Biol. Chem. 272, 27678-27685). Here we present a novel ectodermal dysplasia phenotype associated with conditional deletion of p38α MAPK in ectodermal appendages using K14-cre mice (p38α(K14) mice). These mice display impaired patterning of dental cusps and a profound defect in the production and biomechanical strength of dental enamel because of defects in ameloblast differentiation and activity. In the absence of p38α, expression of amelogenin and β4-integrin in ameloblasts and p21 in the enamel knot was significantly reduced. Mice lacking the MAP2K MKK6, but not mice lacking MAP2K MKK3, also show the enamel defects, implying that MKK6 functions as an upstream kinase of p38α in ectodermal appendages. Lastly, stimulation with BMP2/7 in both explant culture and an ameloblast cell line confirm that p38α functions downstream of BMPs in this context. Thus, BMP-induced activation of the p38α MAPK pathway is critical for the morphogenesis of tooth cusps and the secretion of dental enamel. PMID:25406311

  20. Self-cleaning and antibiofouling enamel surface by slippery liquid-infused technique

    PubMed Central

    Yin, JiaLi; Mei, May Lei; Li, QuanLi; Xia, Rong; Zhang, ZhiHong; Chu, Chun Hung

    2016-01-01

    We aimed to create a slippery liquid-infused enamel surface with antibiofouling property to prevent dental biofilm/plaque formation. First, a micro/nanoporous enamel surface was obtained by 37% phosphoric acid etching. The surface was then functionalized by hydrophobic low-surface energy heptadecafluoro-1,1,2,2-tetra- hydrodecyltrichlorosilane. Subsequent infusion of fluorocarbon lubricants (Fluorinert FC-70) into the polyfluoroalkyl-silanized rough surface resulted in an enamel surface with slippery liquid-infused porous surface (SLIPS). The results of water contact angle measurement, diffuse-reflectance Fourier transform infrared spectroscopy, and atomic force microscope confirmed that the SLIPS was successfully constructed on the enamel surface. The antibiofouling property of the SLIPS was evaluated by the adsorption of salivary protein of mucin and Streptococcus mutans in vitro, as well as dental biofilm formation using a rabbit model in vivo. The results showed that the SLIPS on the enamel surface significantly inhibited mucin adhesion and S. mutans biofilm formation in vitro, and inhibited dental plaque formation in vivo. PMID:27181424

  1. UR 501, the Plio-Pleistocene hominid from Malawi. Analysis of the microanatomy of the enamel

    NASA Astrophysics Data System (ADS)

    Ramirez Rozzi, Fernando V.; Bromage, Tim; Schrenk, Friedemann

    1997-08-01

    The study of enamel microstructure characteristics was carried out in a mandible of a Plio-Pleistocene hominid (UR 501), found in Chiwondo Beds at Uraha (northern Malawi), dated around 2.5-2.3 Myrs, and attributed to Homo rudolfensis. It indicates that UR 501 dental development shares many patterns with other Plio-Pleistocene hominids, i.e. similar crown formation time in premolars and molars. Nevertheless, differences were found, especially in the lateral enamel thickness. In premolars, lateral enamel is as thin as in early Homo, and in molars it is as thick as in robust australopithecines from East Turkana. The difference between enamel lateral thickness in premolars and molars in UR 501, which is not found in another specimen attributed to H. rudolfensis (KNM-ER 1802), may indicate inter-populational variation in H. rudolfensis.

  2. Evaluation of enamel pearls by cone-beam computed tomography (CBCT)

    PubMed Central

    Akgül, Nilgün; Caglayan, Fatma; Durna, Nurhan; Sümbüllü, Muhammed A.; Akgül, Hayati M.; Durna, Dogan

    2012-01-01

    Objective: The aim of this study was to evaluate the frequency of enamel pearls according to population, sex and tooth groups on Cone-Beam Computed Tomography (CBCT) or Dental Volumetric Tomography (DVT) scans of patients, retrospectively. Study Design: In this study, 15185 teeth belonging to 768 patients, 430 female and 338 male, was performed cross-sectional examination by CBCT. The volumetric Computed Tomography used in the study is Newton FP based on flat-panel. The data were analyzed with Pearson chi-squared test. Results: Enamel pearls were detected in 36 subjects (4.69%). Of these enamel pearls, 19 were detected in male and 17 were in male. There was no statistically a significant association between prevalence of enamel pearls and sex. All of enamel pearls were detected in molar teeth, for prevalence 0.83%. Conclusion: All of enamel pearls are found upper and lower molar teeth, especially the most commonly in maxillary second and third molars. Key words: Enamel pearls, ectopic mineralization, radiography, CBCT, DVT. PMID:22143707

  3. X-linked hypophosphatemic rickets: enamel abnormalities and oral clinical findings.

    PubMed

    Cremonesi, Ilaria; Nucci, Cesare; D'Alessandro, Giovanni; Alkhamis, Nadia; Marchionni, Silvia; Piana, Gabriela

    2014-01-01

    X-linked hypophosphatemia (XLH) is a genetic disorder related to alterations in bones and teeth formation, due to low levels of phosphate in blood. Oral findings in XLH have been enamel and dentine abnormalities, high pulp horns, large pulp chambers, and some cases of periapical abscesses related to teeth without caries or traumatic injuries. The aim of our study was to assess the presence of enamel alterations, such as microclefts and/or structure defects in patients with XLH and give guidelines of prevention of XLH dental complications. History taking, oral clinical and radiological examination in 10 young patients affected by XLH (average age of 9) and in 6 patients without XLH (average age of 8). Impressions were performed on the vestibular surfaces of teeth in order to obtain replicas. The replicas were analyzed using scanning electron microscope (SEM) and compared to replicas of control group. The images of replicas of XLH patients showed deep microclefts and irregular enamel surface structure compared to replicas of control group. The replica of a patient with spontaneous periapical abscesses showed numerous enamel crater-shaped depressions and deep microcleavages penetrating into the enamel thickness. In absence of caries or fractures, the abscesses pathogenesis may be related to microcleavages of the enamel and dentin, which allow bacterial invasion of the pulp. There could be a relationship between XLH disease and enamel abnormalities. PMID:24677288

  4. Effects of chlorhexidine and fluoride on irradiated enamel and dentin.

    PubMed

    Soares, C J; Neiva, N A; Soares, P B F; Dechichi, P; Novais, V R; Naves, L Z; Marques, M R

    2011-05-01

    The effectiveness of mouthwash protocols in preventing gamma irradiation therapy damage to the ultimate tensile strength (UTS) of enamel and dentin is unknown. It was hypothesized that the use of chlorhexidine and fluoride mouthwash would maintain the UTS of dental structures. One hundred and twenty teeth were divided into 2 groups: irradiated (subjected to 60 Gy of gamma irradiation in daily increments of 2 Gy) and non-irradiated. They were then subdivided into 2 mouthwash protocols used 3 times per day: 0.12% chlorhexidine, 0.05% sodium fluoride, and control group (n = 10). The specimens were evaluated by microtensile testing. The results of the Tukey test (p < 0.05) indicated that the gamma irradiation therapy significantly reduced the UTS of the enamel, crown, and root dentin. Macromolecular alterations were suggested by optical retardation data in dentin. Structural alterations, in both substrates, were detected by scanning electron microscopy analysis. Mouthwash with 0.12% chlorhexidine partially prevented the damage to the mechanical properties of the irradiated crown dentin, whereas the 0.05% sodium-fluoride-irradiated enamel showed UTS similar to that of non-irradiated enamel. PMID:21335538

  5. Nanobacteria's potential involvement in enamel repair in caries.

    PubMed

    Jing, Junjun; Lu, Junjun; Hao, Yuqing; Han, Yaolun

    2009-09-01

    Dental caries is the accumulation of numerous episodes of demineralization and remineralization, rather than a unidirectional demineralization process. Demineralization and remineralization occur constantly either simultaneously or alternately and whether a lesion will progress or be repaired depends upon the predominant process over periods. Even if fluoride has demonstrated the anti-caries effect by shifting the demineralization/remineralization balance favorably, little is known about non-fluoride action in favor of the balance and the effect of fluoride could not fully explain enamel repair in caries. Recently, in vitro experiments demonstrated enamel repair by synthetic apatite nanocrystals which showed the strong affinity, excellent biocompatibility, mechanical improvement, and a higher resistance to acids than apatite from teeth. This reminds us of a controversial microorganism called nanobacteria (NB) which form nanocrystalline apatite around themselves. Although NB have been detected in some pathological calcifications, epidemiologic literature suggests that they are widespread present in the healthy people blood. Considering the similarity of synthetic nanocrystalline apatite to that of NB and blood circulation communicating with saliva, we put forward a hypothesis that NB may act in enamel surface just like what the synthetic nanocrystalline apatite does in vitro to repair enamel in caries. PMID:19409717

  6. Enamel inspired nano-composite fabrication through amelogenin supramolecular assembly

    PubMed Central

    Fan, Yuwei; Sun, Zhi; Wang, Rizhi; Abbott, Christopher; Moradian-Oldak, Janet

    2007-01-01

    Fabricating the structures similar to dental enamel through the in vitro preparation method is of great interest in the field of dentistry and material science. Developing enamel is composed of calcium phosphate mineral, water, and enamel matrix proteins, mainly amelogenins. To prepare a material mimicking such composition a novel approach of simultaneously assembling amelogenin and calcium phosphate precipitates by electrolytic deposition was established. It was found that recombinant full-length amelogenin (rP172) self-assembled into nanochain structures during electrolytic deposition (following increase in solution pH), and had significant effect on the induction of the parallel bundles of calcium phosphate nanocrystals, grown on semiconductive silicon wafer surface. When a truncated amelogenin (rP148) was used; no nano-chain assembly was observed, neither parallel bundles were formed. The coating obtained in the presence of rP172 had improved elastic modulus and hardness when compared to the coating incorporated with rP148. Our data suggest that the formation of organized bundles in amelogenin-apatite composites is mainly driven by amelogenin nanochain assembly and highlights the potential of such composite for future application as dental restorative materials. PMID:17382381

  7. Dental Amalgam

    MedlinePlus

    ... Products and Medical Procedures Dental Devices Dental Amalgam Dental Amalgam Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Dental amalgam is a dental filling material which is ...

  8. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, D.C.

    1987-11-20

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compound of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved. 2 figs.

  9. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, Daniel C.

    1990-01-01

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  10. Porcelain enamel neutron absorbing material

    DOEpatents

    Iverson, Daniel C.

    1990-02-06

    A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

  11. Dental microwear. Morphological, functional and phylogenetic correlations.

    PubMed

    Villa, G; Giacobini, G

    1998-01-01

    Dental wear, at first considered a pathological condition, is now regarded as a physiological mechanism of teeth adaptation to continuous masticatory stresses. Excessive wear is limited by characteristic structural adaptations of dental hard tissues showing a phylogenetic trend and specialisation. Enamel is the main tissue subjected to wear; however, advanced enamel wear exposes increasingly large areas of dentine. Enamel hardness and anisotropy are the major factors contrasting wear and microfractures. Anisotropy is mainly related to the different orientation of prism bundles (and of hydroxiapatite cristals). Enamel wear development is also related to differences in microhardness, density, mineral composition and protein distribution. Masticatory loads distributed along the enamel-dentine junction uniformly disperse in the underlying dentine. In spite of its structural characteristics, dentine is relatively isotropic by the functional point of view. Even if its lower hardness opposes less efficaciously to wear, its biomechanical characteristics successfully contrast microfractures. The study of microwear (namely the microscopic analysis of worn dental surfaces) can be made both on original surfaces and on high definition silicone-resin replicas. Scanning electron microscope observations allow identification of surface damage (microtraces) produced by different physical and chemical agents. Microwear analysis may provide indications about alimentary and non alimentary habits, masticatory biomechanics and pathological situations (e.g., bruxism). PMID:9766174

  12. Fluoride affects enamel protein content via TGF-β1-mediated KLK4 inhibition.

    PubMed

    Suzuki, M; Shin, M; Simmer, J P; Bartlett, J D

    2014-10-01

    Dental fluorosis is caused by chronic high-level fluoride (F(-)) exposure during enamel development, and fluorosed enamel has a higher than normal protein content. Matrix metalloproteinase 20 cleaves enamel matrix proteins during the secretory stage, and KLK4 further cleaves these proteins during the maturation stage so that the proteins can be reabsorbed from the hardening enamel. We show that transforming growth factor β1 (TGF-β1) can induce Klk4 expression, and we examine the effect of F(-) on TGF-β1 and KLK4 expression. We found that in vivo F(-) inhibits Klk4 but not Mmp20 transcript levels. LacZ-C57BL/6-Klk4 (+/LacZ) mice have LacZ inserted in frame at the Klk4 translation initiation site so that the endogenous Klk4 promoter drives LacZ expression in the same temporal/spatial way as it does for Klk4. KLK4 protein levels in rat enamel and β-galactosidase staining in LacZ-C57BL/6-Klk4 (+/LacZ) mouse enamel were both significantly reduced by F(-) treatment. Since TGF-β1 induces KLK4 expression, we tested and found that F(-) significantly reduced Tgf-β1 transcript levels in rat enamel organ. These data suggest that F(-)-mediated downregulation of TGF-β1 expression contributes to reduced KLK4 protein levels in fluorosed enamel and provides an explanation for why fluorosed enamel has a higher than normal protein content. PMID:25074495

  13. Comparison of reflectance spectra of sound and carious enamel

    NASA Astrophysics Data System (ADS)

    Analoui, Mostafa; Ando, Masatoshi; Stookey, George K.

    2000-03-01

    Development of dental caries is associated with the loss of minerals and change in the enamel structure. In this study, we have measured and compared reflectance spectra of sound and carious enamel, to investigate its utility in detection and analysis of dental caries. One hundred twenty, 3-mm diameter human enamel cores, with no sign of fluorosis, tetracycline stain, hypoplasia, fracture and restorations, were prepared. The enamel surfaces then were ground and polished. Specimens were placed on a fitted holder with either black or white color for background, with no fluorescence. The baseline spectra were measured using a spectrophotometer with enclosed diffused illumination. Spectra measured from 380 to 780 nm at 5 nm intervals. All measurements were corrected to compensate for the spectrum of illumination. The specimens were divided into two groups and exposed to a demineralizing solution, for 48 and 96 hours, respectively. Reflectance spectra of specimens were measured following lesion induction. All specimens were sectioned and analyzed by transverse microradiography (TMR), where lesion depth and mineral loss ((Delta) Z) were measured. Dimensionality of multi-spectral data was reduced through its conversion to L*a*b* color coordinates and principal component analysis (PCA). Multiple linear regression analysis showed low correlation between L*a*b* and lesion depth and mineral loss. PCA analysis showed higher correlation coefficient, compared to L*a*b*. Preliminary results of this study suggest that multi-spectral measurement and analysis of the tooth surface could be useful in predicting the depth and severity of an early carious lesion.

  14. The diffusion in vitro of fluoride and chlorhexidine in the enamel of human deciduous and permanent teeth.

    PubMed

    Lindén, L A; Björkman, S; Hattab, F

    1986-01-01

    The permeability of human dental enamel was studied by following the diffusion of [51Cr]-ethylenediaminetetraacetate (EDTA), F and [14C]-chlorhexidine using two-chamber diffusion cells. The [51Cr]-EDTA served as a marker to control the change in enamel permeability during the diffusion process. An average increase in enamel permeability of about 1.6-fold was recorded following the initial diffusion of the test compounds in the deciduous and permanent enamel. The permeability of deciduous enamel was much higher than that of permanent enamel. For [51Cr]-EDTA and [14C]-chlorhexidine, the average diffusion coefficient was about 30-fold more than in permanent enamel; for F it was 150-fold more. The difference was statistically significant (p less than 0.001). Co-administration of F and [14C]-chlorhexidine showed a higher diffusion rate for each compound than when separately diffused. Whether this is due to a synergetic effect or to increased enamel permeability following the initial diffusion of the compound, or both, is still uncertain. PMID:3085643

  15. Effects of fluoride on matrix proteins and their properties in rat secretory enamel.

    PubMed

    Aoba, T; Moreno, E C; Tanabe, T; Fukae, M

    1990-06-01

    This publication concerns the selective adsorption of rat enamel proteins onto hydroxyapatite, their solubility in aqueous solutions, and the effect that systemic fluoride has on these properties. The enamel proteins used as adsorbates were extracted in 0.5 mol/L acetic acid from the secretory enamel of the upper and lower incisors of SD rats (females, 200-220 g body weight). Equilibration of the proteins with hydroxyapatite was performed in two solutions: (i) 50 mmol/L acetate buffer at pH 6.0 and 0 degrees C, and (ii) 50 mmol/L Tris buffer containing 4 mol/L guanidine at pH 7.4 and room temperature. Enamel was dissected from animals, which were given either de-ionized water (control group) or water containing 25, 50, 75, or 100 ppm fluoride as NaF for four weeks. From these enamel samples, the proteins were extracted in sequence with 160 mmol/L NaCl and 3 mmol/L phosphate (pH 7.3), 50 mmol/L carbonate buffer (pH 10.8), and finally, with 0.5 mol/L acetic acid for dissolution of the enamel mineral. The F, Ca, and P contents of the various enamel samples were determined.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2162362

  16. Amelogenin in Enamel Tissue Engineering

    PubMed Central

    2016-01-01

    In this chapter the basic premises, the recent findings and the future challenges in the use of amelogenin for enamel tissue engineering are being discoursed on. Results emerging from the experiments performed to assess the fundamental physicochemical mechanisms of the interaction of amelogenin, the main protein of the enamel matrix, and the growing crystals of apatite, are mentioned, alongside a moderately comprehensive literature review of the subject at hand. The clinical importance of understanding this protein/mineral interaction at the nanoscale are highlighted as well as the potential for tooth enamel to act as an excellent model system for studying some of the essential aspects of biomineralization processes in general. The dominant paradigm stating that amelogenin directs the uniaxial growth of apatite crystals in enamel by slowing down the growth of (hk0) faces on which it adheres is being questioned based on the results demonstrating the ability of amelogenin to promote the nucleation and crystal growth of apatite under constant titration conditions designed to mimic those present in the developing enamel matrix. The role of numerous minor components of the enamel matrix is being highlighted as essential and impossible to compensate for by utilizing its more abundant ingredients only. It is concluded that the three major aspects of amelogenesis outlined hereby – (1) the assembly of amelogenin and other enamel matrix proteins, (2) the proteolytic activity, and (3) crystallization – need to be in precise synergy with each other in order for the grounds for the proper imitation of amelogenesis in the lab to be created. PMID:26545753

  17. Amelogenin in Enamel Tissue Engineering.

    PubMed

    Uskoković, Vuk

    2015-01-01

    In this chapter the basic premises, the recent findings and the future challenges in the use of amelogenin for enamel tissue engineering are being discoursed on. Results emerging from the experiments performed to assess the fundamental physicochemical mechanisms of the interaction of amelogenin, the main protein of the enamel matrix, and the growing crystals of apatite, are mentioned, alongside a moderately comprehensive literature review of the subject at hand. The clinical importance of understanding this protein/mineral interaction at the nanoscale are highlighted as well as the potential for tooth enamel to act as an excellent model system for studying some of the essential aspects of biomineralization processes in general. The dominant paradigm stating that amelogenin directs the uniaxial growth of apatite crystals in enamel by slowing down the growth of (hk0) faces on which it adheres is being questioned based on the results demonstrating the ability of amelogenin to promote the nucleation and crystal growth of apatite under constant titration conditions designed to mimic those present in the developing enamel matrix. The role of numerous minor components of the enamel matrix is being highlighted as essential and impossible to compensate for by utilizing its more abundant ingredients only. It is concluded that the three major aspects of amelogenesis outlined hereby--(1) the assembly of amelogenin and other enamel matrix proteins, (2) the proteolytic activity, and (3) crystallization--need to be in precise synergy with each other in order for the grounds for the proper imitation of amelogenesis in the lab to be created. PMID:26545753

  18. Enamel Surface with Pit and Fissure Sealant Containing 45S5 Bioactive Glass.

    PubMed

    Yang, S-Y; Kwon, J-S; Kim, K-N; Kim, K-M

    2016-05-01

    Enamel demineralization adjacent to pit and fissure sealants leads to the formation of marginal caries, which can necessitate the replacement of existing sealants. Dental materials with bioactive glass, which releases ions that inhibit dental caries, have been studied. The purpose of this study was to evaluate the enamel surface adjacent to sealants containing 45S5 bioactive glass (BAG) under simulated microleakage between the material and the tooth in a cariogenic environment. Sealants containing 45S5BAG filler were prepared as follows: 0% 45S5BAG + 50.0% glass (BAG0 group), 12.5% 45S5BAG + 37.5% glass (BAG12.5 group), 25.0% 45S5BAG + 25.0% glass (BAG25.0 group), 37.5% 45S5BAG + 12.5% glass (BAG37.5 group), and 50.0% 45S5BAG + 0% glass (BAG50.0 group). A cured sealant disk was placed over a flat bovine enamel disk, separated by a 60-µm gap, and immersed in lactic acid solution (pH 4.0) at 37 °C for 15, 30, and 45 d. After the storage period, each enamel disk was separated from the cured sealant disk, and the enamel surface was examined with optical 3-dimensional surface profilometer, microhardness tester, and scanning electron microscopy. The results showed a significant increase in roughness and a decrease in microhardness of the enamel surface as the proportion of 45S5BAG decreased (P< 0.05). In the scanning electron microscopy images, enamel surfaces with BAG50.0 showed a smooth surface, similar to those in the control group with distilled water, even after prolonged acid storage. Additionally, an etched pattern was observed on the surface of the demineralized enamel with a decreasing proportion of 45S5BAG. Increasing the 45S5BAG filler contents of the sealants had a significant impact in preventing the demineralization of the enamel surface within microgaps between the material and the tooth when exposed to a cariogenic environment. Therefore, despite some marginal leakage, these novel sealants may be effective preventive dental materials for inhibiting

  19. Optical detection dental disease using polarized light

    DOEpatents

    Everett, Matthew J.; Colston, Jr., Billy W.; Sathyam, Ujwal S.; Da Silva, Luiz B.; Fried, Daniel

    2003-01-01

    A polarization sensitive optical imaging system is used to detect changes in polarization in dental tissues to aid the diagnosis of dental disease such as caries. The degree of depolarization is measured by illuminating the dental tissue with polarized light and measuring the polarization state of the backscattered light. The polarization state of this reflected light is analyzed using optical polarimetric imaging techniques. A hand-held fiber optic dental probe is used in vivo to direct the incident beam to the dental tissue and collect the reflected light. To provide depth-resolved characterization of the dental tissue, the polarization diagnostics may be incorporated into optical coherence domain reflectometry and optical coherence tomography (OCDR/OCT) systems, which enables identification of subsurface depolarization sites associated with demineralization of enamel or bone.

  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. Matrix--mineral relationships in enamel tissues.

    PubMed

    Fearnhead, R W

    1979-03-01

    A personal view of vertebrate enamels and their matrix-mineral relationships is given by first considering enamel types and speculating on the nature, distribution, formation and role of enamel protein. Not all the work consulted is mentioned in the text. The additional works are, however, included in the list of references. PMID:283133

  2. Tissue mimicking materials for dental ultrasound.

    PubMed

    Singh, Rahul S; Culjat, Martin O; Grundfest, Warren S; Brown, Elliott R; White, Shane N

    2008-04-01

    While acoustic tissue mimicking materials have been explored for a variety of soft and hard biological tissues, no dental hard tissue mimicking materials have been characterized. Tooth phantoms are necessary to better understand acoustic phenomenology within the tooth environment and to accelerate the advancement of dental ultrasound imaging systems. In this study, soda lime glass and dental composite were explored as surrogates for human enamel and dentin, respectively, in terms of compressional velocity, attenuation, and acoustic impedance. The results suggest that a tooth phantom consisting of glass and composite can effectively mimic the acoustic behavior of a natural human tooth. PMID:18396919

  3. Numerical analysis of human dental occlusal contact

    NASA Astrophysics Data System (ADS)

    Bastos, F. S.; Las Casas, E. B.; Godoy, G. C. D.; Meireles, A. B.

    2010-06-01

    The purpose of this study was to obtain real contact areas, forces, and pressures acting on human dental enamel as a function of the nominal pressure during dental occlusal contact. The described development consisted of three steps: characterization of the surface roughness by 3D contact profilometry test, finite element analysis of micro responses for each pair of main asperities in contact, and homogenization of macro responses using an assumed probability density function. The inelastic deformation of enamel was considered, adjusting the stress-strain relationship of sound enamel to that obtained from instrumented indentation tests conducted with spherical tip. A mechanical part of the static friction coefficient was estimated as the ratio between tangential and normal components of the overall resistive force, resulting in μd = 0.057. Less than 1% of contact pairs reached the yield stress of enamel, indicating that the occlusal contact is essentially elastic. The micro-models indicated an average hardness of 6.25GPa, and the homogenized result for macroscopic interface was around 9GPa. Further refinements of the methodology and verification using experimental data can provide a better understanding of processes related to contact, friction and wear of human tooth enamel.

  4. Effect of fluoride mouthrinsing on caries lesion development in shark enamel: an in situ caries model study.

    PubMed

    Ogaard, B; Rölla, G; Dijkman, T; Ruben, J; Arends, J

    1991-10-01

    Shark enamel consists of nearly pure fluorapatite and has been shown to demineralize in an in situ caries model. The present study was conducted to investigate whether additional fluoride supplementation in the form of mouthrinsing would inhibit lesion development in shark enamel. The study slabs of shark enamel were mounted in dental appliances. Six individuals wore the appliances while rinsing daily with a neutral 0.2% NaF solution for 4 wk. The specimens were analyzed by means of quantitative microradiography, and the data compared with a previous study using untreated shark enamel and the same participants. It was found that fluoride rinsing did not measurably inhibit enamel demineralization in 4 wk. Scanning electron microradiographs showed that calcium fluoride-like material was not formed on shark enamel after neutral fluoride treatment, supporting a previous study. The present study indicates, therefore, that formation of a calcium fluoride-like material on the enamel surface may be essential for the cariostatic effect of topical agents. PMID:1754838

  5. Enamel hypoplasia in the middle pleistocene hominids from Atapuerca (Spain).

    PubMed

    Bermúdez de Castro, J M; Pérez, P J

    1995-03-01

    The prevalence and chronology of enamel hypoplasias were studied in a hominid dental sample from the Sima de los Huesos (SH) Middle Pleistocene site at the Sierra de Atapuerca (Burgos, northern Spain). A total of 89 permanent maxillary teeth, 143 permanent mandibular teeth, and one deciduous lower canine, belonging to a minimum of 29 individuals, were examined. Excluding the antimeres (16 maxillary and 37 mandibular cases) from the sample, the prevalence of hypoplasias in the permanent dentition is 12.8% (23/179), whereas the deciduous tooth also showed an enamel defect. No statistically significant differences were found between both arcades and between the anterior and postcanine teeth for the prevalence of hypoplasias. In both the maxilla and the mandible the highest frequency of enamel hypoplasias was recorded in the canines. Only one tooth (a permanent upper canine) showed two different enamel defects, and most of the hypoplasias were expressed as faint linear horizontal defects. Taking into account the limitations that the incompleteness of virtually all permanent dentitions imposes, we have estimated that the frequency by individual in the SH hominid sample was not greater than 40%. Most of the hypoplasias occurred between birth and 7 years (N = 18, X = 3.5, SD = 1.3). Both the prevalence and severity of the hypoplasias of the SH hominid sample are significantly less than those of a large Neandertal sample. Furthermore, prehistoric hunter-gatherers and historic agricultural and industrial populations exhibit a prevalence of hypoplasias generally higher than that of the SH hominids. Implications for the survival strategies and life quality of the SH hominids are also discussed. PMID:7785727

  6. The effect of enamel proteins on erosion

    NASA Astrophysics Data System (ADS)

    Baumann, T.; Carvalho, T. S.; Lussi, A.

    2015-10-01

    Enamel proteins form a scaffold for growing hydroxyapatite crystals during enamel formation. They are then almost completely degraded during enamel maturation, resulting in a protein content of only 1% (w/v) in mature enamel. Nevertheless, this small amount of remaining proteins has important effects on the mechanical and structural properties of enamel and on the electrostatic properties of its surface. To analyze how enamel proteins affect tooth erosion, human enamel specimens were deproteinated. Surface microhardness (SMH), surface reflection intensity (SRI) and calcium release of both deproteinated and control specimens were monitored while continuously eroding them. The deproteination itself already reduced the initial SMH and SRI of the enamel significantly (p < 0.001 and p < 0.01). During the course of erosion, the progression of all three evaluated parameters differed significantly between the two groups (p < 0.001 for each). The deproteinated enamel lost its SMH and SRI faster, and released more calcium than the control group, but these differences were only significant at later stages of erosion, where not only surface softening but surface loss can be observed. We conclude that enamel proteins have a significant effect on erosion, protecting the enamel and slowing down the progression of erosion when irreversible surface loss starts to occur.

  7. The effect of enamel proteins on erosion

    PubMed Central

    Baumann, T.; Carvalho, T. S.; Lussi, A.

    2015-01-01

    Enamel proteins form a scaffold for growing hydroxyapatite crystals during enamel formation. They are then almost completely degraded during enamel maturation, resulting in a protein content of only 1% (w/v) in mature enamel. Nevertheless, this small amount of remaining proteins has important effects on the mechanical and structural properties of enamel and on the electrostatic properties of its surface. To analyze how enamel proteins affect tooth erosion, human enamel specimens were deproteinated. Surface microhardness (SMH), surface reflection intensity (SRI) and calcium release of both deproteinated and control specimens were monitored while continuously eroding them. The deproteination itself already reduced the initial SMH and SRI of the enamel significantly (p < 0.001 and p < 0.01). During the course of erosion, the progression of all three evaluated parameters differed significantly between the two groups (p < 0.001 for each). The deproteinated enamel lost its SMH and SRI faster, and released more calcium than the control group, but these differences were only significant at later stages of erosion, where not only surface softening but surface loss can be observed. We conclude that enamel proteins have a significant effect on erosion, protecting the enamel and slowing down the progression of erosion when irreversible surface loss starts to occur. PMID:26468660

  8. Near-IR Imaging of Thermal Changes in Enamel during Laser Ablation

    PubMed Central

    Maung, Linn H.; Lee, Chulsung; Fried, Daniel

    2011-01-01

    The objective of this work was to observe the various thermal-induced optical changes that occur in the near-infrared (NIR) during drilling in dentin and enamel with the laser and the high-speed dental handpiece. Tooth sections of ~ 3 mm-thickness were prepared from extracted human incisors (N=60). Samples were ablated with a mechanically scanned CO2 laser operating at a wavelength of 9.3-µm, a 300-Hz laser pulse repetition rate, and a laser pulse duration of 10–20 µs. An InGaAs imaging camera was used to acquire real-time NIR images at 1300-nm of thermal and mechanical changes (cracks). Enamel was rapidly removed by the CO2 laser without peripheral thermal damage by mechanically scanning the laser beam while a water spray was used to cool the sample. Comparison of the peripheral thermal and mechanical changes produced while cutting with the laser and the high-speed hand-piece suggest that enamel and dentin can be removed at high speed by the CO2 laser without excessive peripheral thermal or mechanical damage. Only 2 of the 15 samples ablated with the laser showed the formation of small cracks while 9 out of 15 samples exhibited crack formation with the dental hand-piece. The first indication of thermal change is a decrease in transparency due to loss of the mobile water from pores in the enamel which increase light-scattering. To test the hypothesis that peripheral thermal changes were caused by loss of mobile water in the enamel, thermal changes were intentionally induced by heating the surface. The mean attenuation coefficient of enamel increased significantly from 2.12 ± 0.82 to 5.08 ± 0.98 with loss of mobile water due to heating. PMID:21935291

  9. Dental calculus image based on optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Hsieh, Yao-Sheng; Ho, Yi-Ching; Lee, Shyh-Yuan; Chuang, Ching-Cheng; Wang, Chun-Yang; Sun, Chia-Wei

    2011-03-01

    In this study, the dental calculus was characterized and imaged by means of swept-source optical coherence tomography (SSOCT). The refractive indices of enamel, dentin, cementum and calculus were measured as 1.625+/-0.024, 1.534+/-0.029, 1.570+/-0.021 and 1.896+/-0.085, respectively. The dental calculus lead strong scattering property and thus the region can be identified under enamel with SSOCT imaging. An extracted human tooth with calculus was covered by gingiva tissue as in vitro sample for SSOCT imaging.

  10. Fiber optic based optical coherence tomography (OCT) for dental applications

    SciTech Connect

    Everett, M. J., LLNL

    1998-06-02

    We have developed a hand-held fiber optic based optical coherence tomography (OCT) system for scanning of the oral cavity We have produced, using this scanning device, in viva cross-sectional images of hard and soft dental tissues in human volunteers Clinically relevant anatomical structures, including the gingival margin, periodontal sulcus, and dento-enamel junction, were visible in all the images The dento-enamel junction and the alveolar bone were identifiable in approximately two thirds of the images These images represent, to our knowledge, the first in viva OCT images of human dental tissue.