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Sample records for enamel subsurface lesions

  1. Remineralization of enamel subsurface lesions by chewing gum with added calcium.

    Science.gov (United States)

    Cai, Fan; Shen, Peiyan; Walker, Glenn D; Reynolds, Coralie; Yuan, Yi; Reynolds, Eric C

    2009-10-01

    Chewing sugar-free gum has been shown to promote enamel remineralization. Manufacturers are now adding calcium to the gum in an approach to further promote enamel remineralization. The aim of this study was to compare the remineralization efficacy of four sugar-free chewing gums, two containing added calcium, utilizing a double-blind, randomized, crossover in situ model. The sugar-free gums were: Trident Xtra Care, Orbit Professional, Orbit and Extra. Ten subjects wore removable palatal appliances with four human-enamel half-slab insets containing subsurface demineralized lesions. For four times a day for 14 consecutive days subjects chewed one of the chewing gums for 20min. After each treatment the enamel slabs were removed, paired with their respective demineralized control slabs, embedded, sectioned and mineral level determined by microradiography. After 1-week rest the subjects chewed another of the four gums and this was repeated until each subject had used the four gum products. Chewing with Trident Xtra Care resulted in significantly higher remineralization (20.67+/-1.05%) than chewing with Orbit Professional (12.43+/-0.64%), Orbit (9.27+/-0.59%) or Extra (9.32+/-0.35%). The form of added calcium in Trident Xtra Care was CPP-ACP and that in Orbit Professional calcium carbonate with added citric acid/citrate for increased calcium solubility. Although saliva analysis confirmed release of the citrate and calcium from the Orbit Professional gum the released calcium did not result in increased enamel remineralization over the normal sugar-free gums. These results highlight the importance of calcium ion bioavailability in the remineralization of enamel subsurface lesions in situ.

  2. A Microbeam Small-Angle X-ray Scattering Study on Enamel Crystallites in Subsurface Lesion

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    Yagi, N; Ohta, N; Matsuo, T [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan); Tanaka, T; Terada, Y; Kamasaka, H; Kometani, T, E-mail: yagi@spring8.or.j [Ezaki Glico Co. Ltd., 4-6-5 Utajima, Nishiyodogawa-ku, Osaka 555-8502 (Japan)

    2010-10-01

    The early caries lesion in bovine tooth enamel was studied by two different X-ray diffraction systems at the SPring-8 third generation synchrotron radiation facility. Both allowed us simultaneous measurement of the small and large angle regions. The beam size was 6{mu}m at BL40XU and 50{mu}m at BL45XU. The small-angle scattering from voids in the hydroxyapatite crystallites and the wide-angle diffraction from the hydroxyapatite crystals were observed simultaneously. At BL40XU an X-ray image intensifier was used for the small-angle and a CMOS flatpanel detector for the large-angle region. At BL45XU, a large-area CCD detector was used to cover both regions. A linear microbeam scan at BL40XU showed a detailed distribution of voids and crystals and made it possible to examine the structural details in the lesion. The two-dimensional scan at BL45XU showed distribution of voids and crystals in a wider region in the enamel. The simultaneous small- and wide-angle measurement with a microbeam is a powerful tool to elucidate the mechanisms of demineralization and remineralization in the early caries lesion.

  3. A Microbeam Small-Angle X-ray Scattering Study on Enamel Crystallites in Subsurface Lesion

    International Nuclear Information System (INIS)

    Yagi, N; Ohta, N; Matsuo, T; Tanaka, T; Terada, Y; Kamasaka, H; Kometani, T

    2010-01-01

    The early caries lesion in bovine tooth enamel was studied by two different X-ray diffraction systems at the SPring-8 third generation synchrotron radiation facility. Both allowed us simultaneous measurement of the small and large angle regions. The beam size was 6μm at BL40XU and 50μm at BL45XU. The small-angle scattering from voids in the hydroxyapatite crystallites and the wide-angle diffraction from the hydroxyapatite crystals were observed simultaneously. At BL40XU an X-ray image intensifier was used for the small-angle and a CMOS flatpanel detector for the large-angle region. At BL45XU, a large-area CCD detector was used to cover both regions. A linear microbeam scan at BL40XU showed a detailed distribution of voids and crystals and made it possible to examine the structural details in the lesion. The two-dimensional scan at BL45XU showed distribution of voids and crystals in a wider region in the enamel. The simultaneous small- and wide-angle measurement with a microbeam is a powerful tool to elucidate the mechanisms of demineralization and remineralization in the early caries lesion.

  4. Enamel subsurface damage due to tooth preparation with diamonds.

    Science.gov (United States)

    Xu, H H; Kelly, J R; Jahanmir, S; Thompson, V P; Rekow, E D

    1997-10-01

    In clinical tooth preparation with diamond burs, sharp diamond particles indent and scratch the enamel, causing material removal. Such operations may produce subsurface damage in enamel. However, little information is available on the mechanisms and the extent of subsurface damage in enamel produced during clinical tooth preparation. The aim of this study, therefore, was to investigate the mechanisms of subsurface damage produced in enamel during tooth preparation by means of diamond burs, and to examine the dependence of such damage on enamel rod orientation, diamond particle size, and removal rate. Subsurface damage was evaluated by a bonded-interface technique. Tooth preparation was carried out on two enamel rod orientations, with four clinical diamond burs (coarse, medium, fine, and superfine) used in a dental handpiece. The results of this study showed that subsurface damage in enamel took the form of median-type cracks and distributed microcracks, extending preferentially along the boundaries between the enamel rods. Microcracks within individual enamel rods were also observed. The median-type cracks were significantly longer in the direction parallel to the enamel rods than perpendicular to the rods. Preparation with the coarse diamond bur produced cracks as deep as 84 +/- 30 microns in enamel. Finishing with fine diamond burs was effective in crack removal. The crack lengths in enamel were not significantly different when the removal rate was varied. Based on these results, it is concluded that subsurface damage in enamel induced by tooth preparation takes the form of median-type cracks as well as inter- and intra-rod microcracks, and that the lengths of these cracks are sensitive to diamond particle size and enamel rod orientation, but insensitive to removal rate.

  5. In vitro remineralization of enamel subsurface lesions and assessment of dentine tubule occlusion from NaF dentifrices with and without calcium

    Directory of Open Access Journals (Sweden)

    A R Prabhakar

    2013-01-01

    Full Text Available Currently, fluoride is the most effective preventive treatment for remineralization of incipient carious lesions and dentinal hypersensitivity due to wasting disorders. The products containing fluoride, calcium and phosphate are also claim to remineralize early, non-cavitated enamel demineralization. The aim of this study was to investigate and compare the efficacy of two such products, Tooth Mousse and Clinpro tooth crème on remineralization and tubule occluding ability with 5000ppm fluoride-containing toothpaste. Materials and Methods :Thirty third molar teeth were placed in demineralizing solution for 5 days such that only a window of 1mm x 5mm was exposed to the environment to produce artificial caries-like lesions and randomly assigned to three groups: Group I, 5000ppm sodium fluoride; Group II, GC MI paste plus and Group III, Clinpro tooth crème. Axial longitudinal sections of 140-160 μm of each tooth which included the artificial carious lesion taken and were photographed under polarized light microscope. The demineralized areas were then quantified with a computerized imaging system. The experimental materials were applied onto the tooth sections as a topical coating and subjected to pH-cycling for 28 days. To evaluate tubule occlusion ability, thirty dentin specimens of 2mm thickness were obtained from cervical third of sound third molars. Specimens were ultrasonicated and etched with 6% citric acid for 2 minutes to simulate the hypersensitive dentin. Specimens were randomly divided into above mentioned three groups (n=10. The test agents were brushed over the specimens with an electric toothbrush, prepared and observed under Scanning Electron Microscope for calculation of the percentage of occluded tubules. Results: Group I showed a significantly greater percentage of remineralization than Group III and Group II. Comparison of the remineralization potential between group II and group III were not significant.In case of dentine

  6. Quantitative study of fluoride transport during subsurface dissolution of dental enamel

    International Nuclear Information System (INIS)

    Chu, J.S.; Fox, J.L.; Higuchi, W.I.

    1989-01-01

    Previous studies using bovine dental enamel as a model have shown that surface and subsurface dissolution of enamel may be governed by micro-environmental solution conditions. We have now investigated the demineralization phenomenon more rigorously with the primary objective of developing a method for deducing solution species concentration profiles as a function of time from appropriate experimental data. More specifically, in this report, a model-independent method is described for determination of the pore solution fluoride gradients in bovine enamel during subsurface demineralization. Microradiography was used to determine the mineral density profiles, and an electron microprobe technique to determine total fluoride (F) profiles associated with the enamel. In each case, matched sections of bovine enamel were exposed to partially saturated acetate buffers at pH = 4.5 containing 0.5 ppm F for various periods of time (from six to 24 hours). The treated enamel was found to have an intact surface layer and subsurface demineralization. The extent of the demineralization and the depths of the lesions increased with time in all cases. The data were first used to calculate (a) the total F gradients in the enamel at various times, and (b) the local uptake rate of F as a function of time and position. Then, by manipulation of the equations describing the uptake and transport of F, we calculated the pore diffusion rate of F and the micro-environmental solution F concentration in the aqueous pores as a function of time and of distance from the enamel surface. It was also possible to calculate an intrinsic F diffusion coefficient in the pores, which was about 1.0 X 10(-5) cm2/sec, in good agreement with reported values

  7. Enamel lesions in development, classification in Costa Rican families

    International Nuclear Information System (INIS)

    Murillo Knudsen, Gina; Berrocal Salazar, Cristina

    2013-01-01

    Enamel lesions in development were identified and classified in patients of Llano Grande de Cartago, examined at the Facultad de Odontologia of the Universidad de Costa Rica. A guide is provided over the topic. 15 children and 2 Costa Rican adults were selected. Clinical examinations, radiographs and clinical photographs were used as data collection method. Dental defects of the enamel were classified according to the possible genetic causes and without genetic causes. Imperfect Amelogenesis (IA) was diagnosed in 10 of patients. Hypoplastic IA was determined in 3 siblings with autosomal recessive inheritance, for 16% of the total sample. Hypomineralized IA was identified in an adult and two of his sons, with autosomal dominant inheritance. The remaining 4 cases of IA have been sporadic. Lesions of dental fluorosis were determined in the Horowitz index in 4 individuals, from 2 unrelated families. Other defects unspecified of the enamel or hypoplasias were found in 3 individuals. Enamel lesions in development should be classified with precision, for the purpose to inform to patients affected about their condition, origin, prognosis and appropriate treatment. The basis are established to implement reliability in the construction of family genealogy, identification and classification of enamel lesions, as well as the probabilities of future generations to express the lesions in the enamel of temporary or permanent dentition [es

  8. Effect of xylitol varnishes on remineralization of artificial enamel caries lesions in vitro.

    Science.gov (United States)

    Cardoso, C A B; de Castilho, A R F; Salomão, P M A; Costa, E N; Magalhães, A C; Buzalaf, M A R

    2014-11-01

    Analyse the effect of varnishes containing xylitol alone or combined with fluoride on the remineralization of artificial enamel caries lesions in vitro. Bovine enamel specimens were randomly allocated to 7 groups (n=15/group). Artificial caries lesions were produced by immersion in 30 mL of lactic acid buffer containing 3mM CaCl2·2H2O, 3mM KH2PO4, 6 μM tetraetil metil diphosphanate (pH 5.0) for 6 days. The enamel blocks were treated with the following varnishes: 10% xylitol; 20% xylitol; 10% xylitol plus F (5% NaF); 20% xylitol plus F (5% NaF); Duofluorid™ (6% NaF, 2.71% F+6% CaF2), Duraphat™ (5% NaF, positive control) and placebo (no-F/xylitol, negative control). The varnishes were applied in a thin layer and removed after 6h. The blocks were subjected to pH-cycles (demineralization-2h/remineralization-22 h during 8 days) and enamel alterations were quantified by surface hardness and transversal microradiography. The percentage of surface hardness recovery (%SHR), the integrated mineral loss and lesion depth were statistically analysed by ANOVA/Tukey's test or Kruskal-Wallis/Dunn's test (pxylitol plus F and 20% xylitol plus F formulations, while significant subsurface mineral remineralization could be seen only for enamel treated with Duraphat™, Duofluorid™ and 20% xylitol formulations. 20% xylitol varnishes seem to be promising alternatives to increase remineralization of artificial caries lesions. effective vehicles are desirable for caries control. Xylitol varnishes seem to be promising alternatives to increase enamel remineralization in vitro, which should be confirmed by in situ and clinical studies. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Effect of xylitol varnishes on remineralization of artificial enamel caries lesions in situ.

    Science.gov (United States)

    Cardoso, C A B; Cassiano, L P S; Costa, E N; Souza-E-Silva, C M; Magalhães, A C; Grizzo, L T; Caldana, M L; Bastos, J R M; Buzalaf, M A R

    2016-07-01

    Analyze the effect of varnishes containing xylitol compared to commercial fluoridated varnishes on the remineralization of artificial enamel caries lesions in situ. Twenty subjects took part in this crossover, double-blind study performed in four phases of 5days each. Each subject worn palatal appliances containing four predemineralized bovine enamel specimens. Artificial caries lesions were produced by immersion in 30ml of lactic acid buffer containing 3mM CaCl2·2H2O, 3mM KH2PO4, 6μM tetraetil metil diphosphanate (pH 5.0) for 6days. The specimens in each subject were treated once with the following varnishes: 20% xylitol (experimental); Duofluorid™ (6% NaF, 6% CaF2), Duraphat™ (5% NaF, positive control) and placebo (no-F/xylitol, negative control). The varnishes were applied in a thin layer and removed after 6h. Fifteen subjects were able to finish all phases. The enamel alterations were quantified by surface hardness and transversal microradiography. The percentage of surface hardness recovery (%SHR), the integrated mineral loss and lesion depth were statistically analyzed by Friedmann and Dunn's tests test (pxylitol formulations. Significant subsurface mineral remineralization could also be seen for the experimental and commercial varnishes, except for Duraphat™, when the parameter "lesion depth" was considered. 20% xylitol varnish seem to be a promising alternative to increase surface and subsurface remineralization of artificial caries lesions in situ. effective vehicles are desirable for caries control. Xylitol varnishes seem to be promising alternatives to increase enamel remineralization in situ, which should be confirmed by clinical studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Elevated fluoride products enhance remineralization of advanced enamel lesions

    NARCIS (Netherlands)

    ten Cate, J.M.; Buijs, M.J.; Chaussain Miller, C.; Exterkate, R.A.M.

    2008-01-01

    Caries prevention might benefit from the use of toothpastes containing over 1500 ppm F. With few clinical studies available, the aim of this pH-cycling study was to investigate the dose response between 0 and 5000 ppm F of de- and remineralization of advanced (> 150 µm) enamel lesions. Treatments

  11. Assessment of natural enamel lesions with optical coherence tomography in comparison with microfocus x-ray computed tomography

    Science.gov (United States)

    Espigares, Jorge; Sadr, Alireza; Hamba, Hidenori; Shimada, Yasushi; Otsuki, Masayuki; Tagami, Junji; Sumi, Yasunori

    2015-01-01

    Abstract. A technology to characterize early enamel lesions is needed in dentistry. Optical coherence tomography (OCT) is a noninvasive method that provides high-resolution cross-sectional images. The aim of this study is to compare OCT with microfocus x-ray computed tomography (μCT) for assessment of natural enamel lesions in vitro. Ten human teeth with visible white spot-like changes on the enamel smooth surface and no cavitation (ICDAS code 2) were subjected to imaging by μCT (SMX-100CT, Shimadzu) and 1300-nm swept-source OCT (Dental SS-OCT, Panasonic Health Care). In μCT, the lesions appeared as radiolucent dark areas, while in SS-OCT, they appeared as areas of increased signal intensity beneath the surface. An SS-OCT attenuation coefficient based on Beer–Lambert law could discriminate lesions from sound enamel. Lesion depth ranged from 175 to 606  μm in SS-OCT. A correlation between μCT and SS-OCT was found regarding lesion depth (R=0.81, p<0.001) and also surface layer thickness (R=0.76, p<0.005). The images obtained clinically in real time using the dental SS-OCT system are suitable for the assessment of natural subsurface lesions and their surface layer, providing comparable images to a laboratory high-resolution μCT without the use of x-ray. PMID:26158079

  12. Remineralization of artificial enamel lesions by theobromine.

    Science.gov (United States)

    Amaechi, B T; Porteous, N; Ramalingam, K; Mensinkai, P K; Ccahuana Vasquez, R A; Sadeghpour, A; Nakamoto, T

    2013-01-01

    This study investigated the remineralization potential of theobromine in comparison to a standard NaF dentifrice. Three tooth blocks were produced from each of 30 teeth. Caries-like lesion was created on each block using acidified gel. A smaller block was cut from each block for baseline scanning electron microscopy imaging and electron-dispersive spectroscopy (EDS) analysis for surface Ca level. A tooth slice was cut from each lesion-bearing block for transverse microradiography (TMR) quantification of baseline mineral loss (Δz) and lesion depth (LD). Then baseline surface microhardness (SMH) of each lesion was measured. The three blocks from each tooth were assigned to three remineralizing agents: (1) artificial saliva; (2) artificial saliva with theobromine (0.0011 mol/l), and (3) NaF toothpaste slurry (0.0789 mol/l F). Remineralization was conducted using a pH cycling model with storage in artificial saliva. After a 28-day cycle, samples were analyzed using EDS, TMR, and SMH. Intragroup comparison of pre- and posttest data was performed using t tests (p theobromine (38 ± 32%) and toothpaste (29 ± 16%). With TMR (Δz/lD), theobromine and toothpaste exhibited significantly (p theobromine and toothpaste was not significantly different. With EDS, calcium deposition was significant in all groups, but not significantly different among the groups (theobromine 13 ± 8%, toothpaste 10 ± 5%, and artificial saliva 6 ± 8%). The present study demonstrated that theobromine in an apatite-forming medium can enhance the remineralization potential of the medium. Copyright © 2013 S. Karger AG, Basel.

  13. In-office bleaching for the remineralization of enamel lesions filled with organic components of red wine.

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    Kunimatsu, Yuichi; Iizuka, Junko; Taniguchi, Motoe; Mikuni-Takagaki, Yuko; Mukai, Yoshiharu

    2018-02-01

    To investigate the effects of in-office bleaching on the remineralization of enamel lesions filled with organic components of red wine. Enamel specimens were exposed to 0.1% NaF solution for 1 minute immersed in red wine for 5 days at 37°C, and subjected to in-office bleaching followed by remineralization in 1.5 mM CaCl₂, 0.9 mM KH₂PO₄, 130 mM KCl, 20 mM HEPES, pH 7.0, at 37°C for 28 days. The presence of organic substances on the enamel surface was detected by Raman spectroscopy. The specimens were also subjected to transverse microradiography (TMR). Raman spectroscopy of baseline lesions showed characteristic peaks at 1,300-1,600 cm-1 which disappeared in bleached specimens. TMR showed that red wine formed subsurface lesions with surface content at approximately 22 mineral volume %. The integrated mineral loss (IML) was significantly lower in unbleached remineralized specimens than at baseline (P 0.05). Lesion depth was significantly lower in the bleached than in the unbleached group (P< 0.05). In-office bleaching can enhance the remineralization of enamel lesions filled with organic components of red wine. Copyright©American Journal of Dentistry.

  14. EFFECT OF FLUORIDE MOUTHRINSING ON CARIES LESION DEVELOPMENT IN SHARK ENAMEL - AN INSITU CARIES MODEL STUDY

    NARCIS (Netherlands)

    OGAARD, B; ROLLA, G; DIJKMAN, T; RUBEN, J; ARENDS, J

    1991-01-01

    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

  15. Effect of tray-based and trayless tooth whitening systems on microhardness of enamel surface and subsurface.

    Science.gov (United States)

    Teixeira, Erica C N; Ritter, André V; Thompson, Jeffrey Y; Leonard, Ralph H; Swift, Edward J

    2004-12-01

    To evaluate the effect of tray-based and trayless tooth whitening systems on surface and subsurface microhardness of human enamel. Enamel slabs were obtained from recently extracted human third molars. Specimens were randomly assigned to six groups according to tooth whitening treatment (n = 10): 6.0% hydrogen peroxide (HP) (Crest Whitestrips), 6.5% HP (Crest Professional Whitestrips), 7.5% HP (Day White Excel 3), 9.5% HP (Day White Excel 3), 10% carbamide peroxide (Opalescence), and a control group (untreated). Specimens were treated for 14 days following manufacturers' recommended protocols, and were immersed in artificial saliva between treatments. Enamel surface Knoop microhardness (KHN) was measured immediately before treatment, and at days 1, 7, and 14 of treatment. After treatment, subsurface microhardness was measured at depths of 50-500 microm. Data were analyzed for statistical significance using analysis of variance. Differences in microhardness for treated vs. untreated enamel surface were not statistically significant at any time interval. For 6.5% and 9.5% HP, there was a decrease in surface microhardness values during treatment, but at the end of treatment the microhardness values were not statistically different from the baseline values. For the enamel subsurface values, no differences were observed between treated vs. untreated specimens at each depth. Trayless and tray-based tooth whitening treatments do not significantly affect surface or subsurface enamel microhardness.

  16. In vitro study on tooth enamel lesions related to whitening dentifrice.

    Science.gov (United States)

    de Araújo, Danilo Barral; Silva, Luciana Rodrigues; Campos, Elisângela de Jesus; Correia de Araújo, Roberto Paulo

    2011-01-01

    The tooth whitening substances for extrinsic use that are available in Brazil contain hydrogen peroxide or carbamide peroxide. Several studies have attributed the appearance of lesions in the enamel morphology, including hypersensitivity, to these substances. Such lesions justify fluoride therapy and application of infrared lasers, among other procedures. However, there is no consensus among researchers regarding the relevance of the severity of lesions detected on the tooth surface. The present study was carried out with an aim of evaluating in vitro the effects of the hydrogen peroxide, carbamide peroxide and sodium bicarbonate contained in dentifrice formulations, on human tooth enamel. After darkening process in laboratory, human premolars were brushed using dentifrice containing the two whitening substances (Rembrandt - carbamide peroxide and Mentadent - hydrogen peroxide) and the abrasive product (Colgate - sodium bicarbonate). The degree of specimen staining before and after this procedure was determined using spectrophotometry. Scanning electron microscopy (SEM) was used to obtain images, which were analyzed to show the nature of the lesions that appeared on the enamel surface. The effectiveness of the whitening caused by hydrogen peroxide and carbamide peroxide and the abrasion caused by bicarbonate were confirmed, given that the treated test pieces returned to their original coloration. Based on SEM, evaluation of the enamel surfaces subjected to the test products showed that different types of morphologic lesions of varying severity appeared. Whitening dentifrice containing hydrogen peroxide and carbamide peroxide produced lesions on the enamel surface such that the greatest sequelae were associated with exposure to hydrogen peroxide.

  17. In vitro remineralization of in vivo and in vitro formed enamel lesions

    NARCIS (Netherlands)

    Iijima, Y; Takagi, O; Ruben, J; Arends, J

    1999-01-01

    Thin sections of natural white spot enamel lesions (WS) and of artificial in vitro lesions (VL) were remineralized simultaneously in vitro. The sections, clamped in a PMMA holder, were microradiographed at baseline and after remineralization in a calcium- and phosphate-containing solution (pH = 7.0;

  18. Relationships between birefringence and mineral content in artificial caries lesions of enamel.

    NARCIS (Netherlands)

    Theuns, H.M.; Shellis, R.P.; Groeneveld, A.; Dijk, J.W. van; Poole, D.F.

    1993-01-01

    The microradiographic mineral content and birefringence in water and Thoulet's solution were measured at selected points in sections of caries-like lesions. Birefringence was not related to mineral content in sound superficial enamel immersed in Thoulet's solution or in the lesion body immersed in

  19. Comparing different enamel pretreatment options for resin-infiltration of natural non-cavitated carious lesions

    NARCIS (Netherlands)

    Abdelaziz, M.; Rizzini, A.L.; Bortolotto, T.; Rocca, G.T.; Feilzer, A.J.; Garcia-Godoy, F.; Krejci, I.

    2016-01-01

    Purpose: To compare two different enamel pretreatments and their effect on the efficiency of penetration of a one-component adhesive into natural carious lesions. Methods: Eight extracted human molars and premolars with non-cavitated interproximal lesions were selected. ICDAS code 1-2 was assessed

  20. Effect of nano-hydroxyapatite concentration on remineralization of initial enamel lesion in vitro

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    Huang, S B; Gao, S S; Yu, H Y, E-mail: yhyang6812@scu.edu.c [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China)

    2009-06-15

    The purpose of the research was to determine the effect of nano-hydroxyapatite concentrations on initial enamel lesions under dynamic pH-cycling conditions. Initial enamel lesions were prepared in bovine enamel with an acidic buffer. NaF (positive control), deionized water (negative control) and four different concentrations of nano-hydroxyapatite (1%, 5%, 10% and 15% wt%) were selected as the treatment agents. Surface microhardness (SMH) measurements were performed before/after demineralization and after 3, 6, 9 and 12 days of application, and the percentage surface microhardness recovery (%SMHR) was calculated. The specimens were then examined by a scanning electron microscope. The %SMHR in nano-hydroxyapatite groups was significantly greater than that of negative control. When the concentration of nano-HA was under 10%, SMH and %SMHR increased with increasing nano-hydroxyapatite concentrations. There were no significant differences between the 10% and 15% groups at different time periods in the pH-cycling. The SEM analysis showed that nano-hydroxyapatite particles were regularly deposited on the cellular structure of the demineralized enamel surface, which appeared to form new surface layers. It was concluded that nano-hydroxyapatite had the potential to remineralize initial enamel lesions. A concentration of 10% nano-hydroxyapatite may be optimal for remineralization of early enamel caries.

  1. Effect of nano-hydroxyapatite concentration on remineralization of initial enamel lesion in vitro

    International Nuclear Information System (INIS)

    Huang, S B; Gao, S S; Yu, H Y

    2009-01-01

    The purpose of the research was to determine the effect of nano-hydroxyapatite concentrations on initial enamel lesions under dynamic pH-cycling conditions. Initial enamel lesions were prepared in bovine enamel with an acidic buffer. NaF (positive control), deionized water (negative control) and four different concentrations of nano-hydroxyapatite (1%, 5%, 10% and 15% wt%) were selected as the treatment agents. Surface microhardness (SMH) measurements were performed before/after demineralization and after 3, 6, 9 and 12 days of application, and the percentage surface microhardness recovery (%SMHR) was calculated. The specimens were then examined by a scanning electron microscope. The %SMHR in nano-hydroxyapatite groups was significantly greater than that of negative control. When the concentration of nano-HA was under 10%, SMH and %SMHR increased with increasing nano-hydroxyapatite concentrations. There were no significant differences between the 10% and 15% groups at different time periods in the pH-cycling. The SEM analysis showed that nano-hydroxyapatite particles were regularly deposited on the cellular structure of the demineralized enamel surface, which appeared to form new surface layers. It was concluded that nano-hydroxyapatite had the potential to remineralize initial enamel lesions. A concentration of 10% nano-hydroxyapatite may be optimal for remineralization of early enamel caries.

  2. Characterization of enamel caries lesions in rat molars using synchrotron X-ray microtomography

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    Free, R.D.; DeRocher, K.; Stock, S.R.; Keane, D.; Scott-Anne, K.; Bowen, W.H.; Joester, D. (Rochester); (NWU)

    2017-08-18

    Dental caries is a ubiquitous infectious disease with a nearly 100% lifetime prevalence. Rodent caries models are widely used to investigate the etiology, progression and potential prevention or treatment of the disease. To explore the suitability of these models for deeper investigations of intact surface zones during enamel caries, the structures of early-stage carious lesions in rats were characterized and compared with previous reports on white spot enamel lesions in humans. Synchrotron X-ray microcomputed tomography non-destructively mapped demineralization in carious rat molar specimens across a range of caries severity, identifying 52 lesions across the 30 teeth imaged. Of these lesions, 13 were shown to have intact surface zones. Depth profiles of fractional mineral density were qualitatively similar to lesions in human teeth. However, the thickness of the surface zone in the rat model ranges from 10 to 58 µm, and is therefore significantly thinner than in human enamel. These results indicate that a fraction of lesions in rat caries possess an intact surface zone and are qualitatively similar to human lesions at the micrometer scale. This suggests that rat caries models may be a suitable analog through which to investigate the structure of surface zone enamel and its role during dental caries.

  3. Susceptibility of bovine dental enamel with initial erosion lesion to new erosive challenges.

    Science.gov (United States)

    Oliveira, Gabriela Cristina de; Tereza, Guida Paola Genovez; Boteon, Ana Paula; Ferrairo, Brunna Mota; Gonçalves, Priscilla Santana Pinto; Silva, Thiago Cruvinel da; Honório, Heitor Marques; Rios, Daniela

    2017-01-01

    This in vitro study evaluated the impact of initial erosion on the susceptibility of enamel to further erosive challenge. Thirty bovine enamel blocks were selected by surface hardness and randomized into two groups (n = 15): GC- group composed by enamel blocks without erosion lesion and GT- group composed by enamel blocks with initial erosion lesion. The baseline profile of each block was determined using the profilometer. The initial erosion was produced by immersing the blocks into HCl 0.01 M, pH 2.3 for 30 seconds, under stirring. The erosive cycling consisted of blocks immersion in hydrochloric acid (0.01 M, pH 2.3) for 2 minutes, followed by immersion in artificial saliva for 120 minutes. This procedure was repeated 4 times a day for 5 days, and the blocks were kept in artificial saliva overnight. After erosive cycling, final profile measurement was performed. Profilometry measured the enamel loss by the superposition of initial and final profiles. Data were analyzed by t-test (perosion on bovine dental enamel does not enhance its susceptibility to new erosive challenges.

  4. Susceptibility of bovine dental enamel with initial erosion lesion to new erosive challenges.

    Directory of Open Access Journals (Sweden)

    Gabriela Cristina de Oliveira

    Full Text Available This in vitro study evaluated the impact of initial erosion on the susceptibility of enamel to further erosive challenge. Thirty bovine enamel blocks were selected by surface hardness and randomized into two groups (n = 15: GC- group composed by enamel blocks without erosion lesion and GT- group composed by enamel blocks with initial erosion lesion. The baseline profile of each block was determined using the profilometer. The initial erosion was produced by immersing the blocks into HCl 0.01 M, pH 2.3 for 30 seconds, under stirring. The erosive cycling consisted of blocks immersion in hydrochloric acid (0.01 M, pH 2.3 for 2 minutes, followed by immersion in artificial saliva for 120 minutes. This procedure was repeated 4 times a day for 5 days, and the blocks were kept in artificial saliva overnight. After erosive cycling, final profile measurement was performed. Profilometry measured the enamel loss by the superposition of initial and final profiles. Data were analyzed by t-test (p<0.05. The result showed no statistically significant difference between groups (GS = 14.60±2.86 and GE = .14.69±2.21 μm. The presence of initial erosion on bovine dental enamel does not enhance its susceptibility to new erosive challenges.

  5. Re- and Demineralization Characteristics of Enamel Depending on Baseline Mineral Loss and Lesion Depth in situ.

    Science.gov (United States)

    Wierichs, Richard J; Lausch, Julian; Meyer-Lueckel, Hendrik; Esteves-Oliveira, Marcella

    2016-01-01

    The aim of this double-blinded, randomized, cross-over in situ study was to evaluate the re- and demineralization characteristics of sound enamel as well as lowly and highly demineralized caries-like enamel lesions after the application of different fluoride compounds. In each of three experimental legs of 4 weeks, 21 participants wore intraoral mandibular appliances containing 4 bovine enamel specimens (2 lowly and 2 highly demineralized). Each specimen included one sound enamel and either one lowly demineralized (7 days, pH 4.95) or one highly demineralized (21 days, pH 4.95) lesion, and was positioned 1 mm below the acrylic under a plastic mesh. The three randomly allocated treatments (application only) included the following dentifrices: (1) 1,100 ppm F as NaF, (2) 1,100 ppm F as SnF2 and (3) 0 ppm F (fluoride-free) as negative control. Differences in integrated mineral loss (x0394;x0394;Z) and lesion depth (x0394;LD) were calculated between values before and after the in situ period using transversal microradiography. Of the 21 participants, 6 did not complete the study and 2 were excluded due to protocol violation. Irrespectively of the treatment, higher baseline mineral loss and lesion depth led to a less pronounced change in mineral loss and lesion depth. Except for x0394;x0394;Z of the dentifrice with 0 ppm F, sound surfaces showed significantly higher x0394;x0394;Z and x0394;LD values compared with lowly and highly demineralized lesions (p test). Re- and demineralization characteristics of enamel depended directly on baseline mineral loss and lesion depth. Treatment groups should therefore be well balanced with respect to baseline mineral loss and lesion depth. © 2016 S. Karger AG, Basel.

  6. In vitro study on tooth enamel lesions related to whitening dentifrice

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    Danilo Barral de Araújo

    2011-01-01

    Full Text Available Background: The tooth whitening substances for extrinsic use that are available in Brazil contain hydrogen peroxide or carbamide peroxide. Several studies have attributed the appearance of lesions in the enamel morphology, including hypersensitivity, to these substances. Such lesions justify fluoride therapy and application of infrared lasers, among other procedures. However, there is no consensus among researchers regarding the relevance of the severity of lesions detected on the tooth surface. Objectives: The present study was carried out with an aim of evaluating in vitro the effects of the hydrogen peroxide, carbamide peroxide and sodium bicarbonate contained in dentifrice formulations, on human tooth enamel. Materials and Methods: After darkening process in laboratory, human premolars were brushed using dentifrice containing the two whitening substances (Rembrandt - carbamide peroxide and Mentadent - hydrogen peroxide and the abrasive product (Colgate - sodium bicarbonate. The degree of specimen staining before and after this procedure was determined using spectrophotometry. Scanning electron microscopy (SEM was used to obtain images, which were analyzed to show the nature of the lesions that appeared on the enamel surface. Results: The effectiveness of the whitening caused by hydrogen peroxide and carbamide peroxide and the abrasion caused by bicarbonate were confirmed, given that the treated test pieces returned to their original coloration. Based on SEM, evaluation of the enamel surfaces subjected to the test products showed that different types of morphologic lesions of varying severity appeared. Conclusions: Whitening dentifrice containing hydrogen peroxide and carbamide peroxide produced lesions on the enamel surface such that the greatest sequelae were associated with exposure to hydrogen peroxide.

  7. Effect of enamel organic matrix on the potential of Galla chinensis to promote the remineralization of initial enamel carious lesions in vitro

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    Zhang Linglin; Zou Ling; Li Jiyao; Hao Yuqing; Xiao Liying; Zhou Xuedong; Li Wei, E-mail: leewei2000@sina.co, E-mail: zhll_sc@yahoo.c [State Key Laboratory of Oral Diseases, West China College of Stomatology, West China Hospital of Stomatology, Sichuan University, Chengdu (China)

    2009-06-15

    Galla chinensis, a natural traditional Chinese medicine with main composition of tannic acid and gallic acid, is formed when the Chinese sumac aphid Baker (Melaphis chinensis bell) parasitizes the levels of Rhus chinensis Mill. Galla chinensis has shown the potential to enhance the remineralization of initial enamel carious lesion, but the mechanism is still unknown. This study was to investigate whether the enamel organic matrix plays a significant role in the potential of Galla chinensis to promote the remineralization of initial enamel caries. Bovine sound enamel blocks and non-organic enamel blocks were demineralized and exposed to a 12 day pH cycling. During the pH cycling, 30 specimens with the enamel organic matrix were randomly divided into three groups, and treated with 1 g L{sup -1} NaF (group A), 4 g L{sup -1} Galla chinensis extract (group B1) or double deionized water (group C1). Twenty specimens without the enamel organic matrix were randomly divided into two groups, and treated with 4 g L{sup -1} Galla chinensis extract (group B2) or double deionized water (group C2). The integrated mineral loss and lesion depth of all the specimens were analysed by transverse microradiography. The integrated mineral loss and lesion depth of group B1 were less than those of groups B2, C1 and C2, and there were no statistical differences among groups B2, C1 and C2. In conclusion, Galla chinensis can enhance the remineralization of initial enamel carious lesion, and the enamel organic matrix plays a significant role in this potential of Galla chinensis.

  8. Lesion dehydration rate changes with the surface layer thickness during enamel remineralization

    Science.gov (United States)

    Chang, Nai-Yuan N.; Jew, Jamison M.; Fried, Daniel

    2018-02-01

    A transparent highly mineralized outer surface zone is formed on caries lesions during remineralization that reduces the permeability to water and plaque generated acids. However, it has not been established how thick the surface zone should be to inhibit the penetration of these fluids. Near-IR (NIR) reflectance coupled with dehydration can be used to measure changes in the fluid permeability of lesions in enamel and dentin. Based on our previous studies, we postulate that there is a strong correlation between the surface layer thickness and the rate of dehydration. In this study, the rates of dehydration for simulated lesions in enamel with varying remineralization durations were measured. Reflectance imaging at NIR wavelengths from 1400-2300 nm, which coincides with higher water absorption and manifests the greatest sensitivity to contrast changes during dehydration measurements, was used to image simulated enamel lesions. The results suggest that the relationship between surface zone thickness and lesion permeability is highly non-linear, and that a small increase in the surface layer thickness may lead to a significant decrease in permeability.

  9. Effect of Enamel Caries Lesion Baseline Severity on Fluoride Dose-Response

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    Frank Lippert

    2017-01-01

    Full Text Available This study aimed to investigate the effect of enamel caries lesion baseline severity on fluoride dose-response under pH cycling conditions. Early caries lesions were created in human enamel specimens at four different severities (8, 16, 24, and 36 h. Lesions were allocated to treatment groups (0, 83, and 367 ppm fluoride as sodium fluoride based on Vickers surface microhardness (VHN and pH cycled for 5 d. The cycling model comprised 3 × 1 min fluoride treatments sandwiched between 2 × 60 min demineralization challenges with specimens stored in artificial saliva in between. VHN was measured again and changes versus lesion baseline were calculated (ΔVHN. Data were analyzed using two-way ANOVA (p<0.05. Increased demineralization times led to increased surface softening. The lesion severity×fluoride concentration interaction was significant (p<0.001. Fluoride dose-response was observed in all groups. Lesions initially demineralized for 16 and 8 h showed similar overall rehardening (ΔVHN and more than 24 and 36 h lesions, which were similar. The 8 h lesions showed the greatest fluoride response differential (367 versus 0 ppm F which diminished with increasing lesion baseline severity. The extent of rehardening as a result of the 0 ppm F treatment increased with increasing lesion baseline severity, whereas it decreased for the fluoride treatments. In conclusion, lesion baseline severity impacts the extent of the fluoride dose-response.

  10. External and internal resin infiltration of natural proximal subsurface caries lesions: A valuable enhancement of the internal tunnel restoration.

    Science.gov (United States)

    Kielbassa, Andrej M; Ulrich, Ina; Werth, Vanessa D; Schüller, Christoph; Frank, Wilhelm; Schmidl, Rita

    2017-01-01

    The aim of this ex-vivo study was to evaluate both the external and the internal penetration ability of a resin infiltrant into natural proximal and macroscopically intact white spot lesions, and to merge this approach with the internal tunnel preparation concept. 20 premolars and 20 molars with proximal subsurface lesions (ICDAS, code 2) and respective radiographic lesion depths extending into the middle third of dentin (D2 lesions) were selected and divided into two groups. Treatment needs were confirmed using digital imaging fiber-optic transillumination and laser fluorescence. Deproteinization (NaOCl; 2%) followed, and lesions of Group 1 (control; n = 20) were etched (HCl; 15%) and externally infiltrated (Icon). Accordingly, the specimens of Group 2 (n = 20) were treated with the resin infiltrant from external; then, internal Class I tunnels were prepared, lesions were internally infiltrated (Icon), and the occlusal cavities were restored (G-ænial Flo X) after etching (H3PO4 gel; 40%). Teeth were cut perpendicular to the proximal lesion surfaces, and percentage infiltrations were analyzed using confocal laser microscopy and a dedicated image manipulation program (GIMP). Regarding the external infiltration, no differences between both groups were detected (P = .114; Mann-Whitney). Additional internal application of the resin infiltrant significantly increased the percentage amount of enamel lesion infiltration (P External and internal infiltration seem to complement the internal tunnel approach, thus remediating the drawbacks of the latter by occluding and stabilizing the porous areas of the proximal caries lesion, and preserving both the marginal ridge and the proximal contact area.

  11. Assessment of enamel-dentin caries lesions detection using bitewing PSP digital images

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    Marianna Guanaes Gomes Torres

    2011-10-01

    Full Text Available OBJECTIVES: The aim of this study was to evaluate the detection of enamel-dentin occlusal caries using photostimulable phosphor plates. MATERIAL AND METHODS: The ability to detect enamel-dentin occlusal caries in 607 premolars and molars from 47 patients between 10 and 18 years old, referred to the School of Dentistry of the Federal University of Bahia, Brazil, was evaluated based on clinical and radiographic examinations, using the criteria proposed in a previous study. A total of 156 bitewing digital images were obtained using Digora® (Soredex Medical Systems, Helsinki, Finland phosphor plates. The plates were scanned and the images were captured and displayed on a computer screen. Image evaluation was done using Digora® for Windows 2.1 software, Soredex®. The radiologists were allowed to use enhancement tools to obtain better visibility during scoring of the teeth based on the radiographic criteria proposed in a previous study. Descriptive analysis and chi-squared proportion tests were done at 5% significance level. RESULTS: The results of clinical examination showed a higher prevalence of teeth with a straight dark line or demineralization of the occlusal fissure (score 1 and a lower prevalence of sealed teeth (score 5. In the bitewing digital images, 47 teeth presented visible radiolucency, circumscribed, in dentin under occlusal enamel (enamel-dentin caries lesions. CONCLUSIONS: Correlating the clinical and radiographic findings, it was found that in the majority of teeth diagnosed by radiographic images as having enamel-dentin caries, no caries could be detected by clinical examination.

  12. The effect of fractional CO2 laser irradiation on remineralization of enamel white spot lesions.

    Science.gov (United States)

    Poosti, Maryam; Ahrari, Farzaneh; Moosavi, Horieh; Najjaran, Hoda

    2014-07-01

    This study investigated the combined effect of fractional CO(2) laser irradiation and fluoride on treatment of enamel caries. Sixty intact premolars were randomly assigned into four groups and then stored in a demineralizing solution to induce white spot lesions. Tooth color was determined at baseline (T1) and after demineralization (T2). Afterwards, the teeth in group 1 remained untreated (control), while group 2 was exposed to an acidulated phosphate fluoride (APF) gel for 4 min. In groups 3 and 4, a fractional CO(2) laser was applied (10 mJ, 200 Hz, 10 s) either before (group 3) or through (group 4) the APF gel. The teeth were then immersed in artificial saliva for 90 days while subjected to daily fluoride mouthrinse and weekly brushing. Color examinations were repeated after topical fluoride application (T3) and 90 days later (T4). Finally, the teeth were sectioned, and microhardness was measured at the enamel surface and at 30 and 60 μ from the surface. In both lased groups, the color change between T1 and T4 stages (∆E(T1-T4)) was significantly lower than those of the other groups (p Laser irradiation followed by fluoride application (group 3) caused a significant increase in surface microhardness compared to APF alone and control groups (p laser before fluoride therapy is suggested for recovering the color and rehardening of demineralized enamel.

  13. Measuring color change of tooth enamel by in vitro remineralization of white spot lesion.

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    Betina Tolcachir

    2015-12-01

    Full Text Available Objective colour determination is based on calculating the colorimetric distance (ΔE within a colour space. So far, the most used colour space in dentistry is CIE L*a*b (Comission Internationale de l´Éclairage. CIE L*C*h* has been recently developed, showing a better correlation with the perception of the human eye. Objective: To determine the ability of an in vitro remineralisation substance to blend the colour of white spot lesions (WSL with sound enamel, determining ΔE by using the CIE L*C*h* colour space. Methods: In vitro WSL was generated by immersing 10 samples obtained from human third molars in a demineralization solution for 72h. Amorphous calcium phosphate stabilized by casein phosphopeptide (CPP-ACP was then applied for 60 days while maintaining the samples in artificial saliva at 37ºC. To evaluate the colour of enamel, images were taken from the samples placed in specifically designed silicone moulds after generating the WSL (pre-stage and after remineralisation by scanning, applying the colorimetric distance equation (ΔE*CMC according to the Colour Measurement Committee. Results: Treatment with CPP-ACP caused a significant ΔE decrease with respect to the pre-stage (p<0.001, while the analysis of parameters that make up the colour showed a reduction in the difference of hue (∆H (p<0.001 and brightness (∆L (p<0.01 after applying CPP-ACP. Discussion: CPP-ACP penetrated to the depth of the white spot lesion, making its appearance similar to that of the sound enamel, probably because of the formation of different mineral phases than that of the original structure, although pores were not completely filled.

  14. In Situ analysis of CO2 laser irradiation on controlling progression of erosive lesions on dental enamel.

    Science.gov (United States)

    Lepri, Taísa Penazzo; Scatolin, Renata Siqueira; Colucci, Vivian; De Alexandria, Adílis Kalina; Maia, Lucianne Cople; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

    2014-08-01

    The present study aimed to evaluate in situ the effect of CO2 laser irradiation to control the progression of enamel erosive lesions. Fifty-six slabs of bovine incisors enamel (5 × 3 × 2.5 mm(3) ) were divided in four distinct areas: (1) sound (reference area), (2) initial erosion, (3) treatment (irradiated or nonirradiated with CO2 laser), (4) final erosion (after in situ phase). The initial erosive challenge was performed with 1% citric acid (pH = 2.3), for 5 min, 2×/day, for 2 days. The slabs were divided in two groups according to surface treatment: irradiated with CO2 laser (λ = 10.6 µm; 0.5 W) and nonirradiate. After a 2-day lead-in period, 14 volunteers wore an intraoral palatal appliance containing two slabs (irradiated and nonirradiated), in two intraoral phases of 5 days each. Following a cross-over design during the first intraoral phase, half of the volunteers immersed the appliance in 100 mL of citric acid for 5 min, 3×/day, while other half of the volunteers used deionized water (control). The volunteers were crossed over in the second phase. Enamel wear was determined by an optical 3D profilometer. Three-way ANOVA for repeated measures revealed that there was no significant interaction between erosive challenge and CO2 laser irradiation (P = 0.419). Erosive challenge significantly increased enamel wear (P = 0.001), regardless whether or not CO2 laser irradiation was performed. There was no difference in enamel wear between specimens CO2 -laser irradiated and non-irradiated (P = 0.513). Under intraoral conditions, CO2 laser irradiation did not control the progression of erosive lesions in enamel caused by citric acid. © 2014 Wiley Periodicals, Inc.

  15. Comparison between Fluoride and Nano-hydroxyapatite in Remineralizing Initial Enamel Lesion: An in vitro Study.

    Science.gov (United States)

    Daas, Issa; Badr, Sherine; Osman, Essam

    2018-03-01

    The aim of this study was to compare the effectiveness of nano-hydroxyapatite (nano-HAP) paste and fluoride varnish in remineralizing initial enamel lesion in young permanent teeth and their ability to resist secondary caries under dynamic pH cycling quantitatively and qualitatively. Initial caries-like lesions were artificially developed on 45 specimens. Specimens were divided into three groups: (1) Control (without treatment), (2) fluoride varnish (3M ESPE), and (3) nano-HAP paste (Desensibilize Nano P). The nano-HAP paste was applied twice separated by one pH cycle, and the varnish was applied only once followed by 7 days of pH cycling. All specimens were examined using DIAGNOdent® pen (KaVo, Germany), and a representative specimen was randomly selected from each group for qualitative evaluation using scanning electron microscope (SEM) at four stages: Baseline, after lesion formation, immediately after remineralization, and after pH cycling. Data were statistically analyzed with Statistical Package for the Social Sciences (SPSS), version 20. The degree of demineralization was significantly elevated in control group; however, no significant difference was found between fluoride varnish group and nano-HAP paste group (p Nano-HAP paste showed promising long-term protective effect in terms of surface depositions and maintaining a smooth surface compared with fluoride varnish. Based on the findings of this study, nano-HAP paste might be recommended as alternative remineralizing agent with lower fluoride concentration than fluoride varnish that could be beneficial for children, pregnant females, and those who are at high risk of dental fluorosis.

  16. Developmental Defects of Enamel : an increasing reality in the everyday practice

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    Fabrizio Guerra

    2014-09-01

    Full Text Available Developmental defects of enamel (DDE are daily encountered in clinical practice. DDE are alteration in quality and quantity of the enamel, caused by disruption and/or damage to the enamel organ during the amelogenesis process. Several clinical indices have been developed to categorize enamel defects based on their nature, appearance, microscopic features or their cause. The aetiology of DDE is not completely clear. Enamel fluorosis is a hypo-mineralization of enamel characterised by subsurface porosity as a result of excess fluoride intake during the period of enamel formation. Several types of treatment have been reported, related to the degree of enamel defect. Correct diagnosis according to lesion depth and prognosis of the technique are fundamental factors in the treatment decision-making process.

  17. Effect of bioglass on artificially induced enamel lesion around orthodontic brackets: OCT study

    Science.gov (United States)

    Bakhsh, Turki; Al-batati, Mohammed; Mukhtar, Mona; Al-Najjar, Mohammed; Bakhsh, Saud; Bakhsh, Abdulsalam; Bakry, Ahmad; Mandurah, Mona; Abbassy, Mona

    2018-02-01

    Background and Objective: White spot lesions (WSLs) are commonly seen after completing orthodontic treatment. Different approaches have been suggested to avoid such a complication. Recently, 45S5 bioglass (BG) was introduced as remineralizing agent. Therefore, the objective of this in-vitro study was to assess the effect of BG in remineralizing WSLs using Optical coherence tomography (OCT). Methods: Fifteen human premolar teeth were sectioned and bonded to orthodontic brackets with Transbond XT primer followed by Transbond PLUS color change adhesive (3M Unitek, USA) on their smooth surfaces according to the manufacturer's instructions. Then, all specimens were varnished excluding the area of interest (AOI) around the bonded restoration, immersed in demineralizing solution and imaged by cross-polarization OCT (CONT group), and the maximum pixel value (MPV) of the AOI were calculated. Then, they were subjected to remineralizing solutions and BG application followed by OCT imaging (REM group). Results: Mann-Whitney test showed the MPV of the AOI in REM was greatly increased and was significantly different from CONT (penamel by MPV technique. The BG has a great potential to remineralize enamel defects, however further investigation is required.

  18. Comparison of Knoop and Vickers surface microhardness and transverse microradiography for the study of early caries lesion formation in human and bovine enamel.

    Science.gov (United States)

    Lippert, F; Lynch, R J M

    2014-07-01

    The aims of the present laboratory study were twofold: a) to investigate the suitability of Knoop and Vickers surface microhardness (SMH) in comparison to transverse microradiography (TMR) to investigate early enamel caries lesion formation; b) to compare the kinetics of caries lesion initiation and progression between human and bovine enamel. Specimens (90×bovine and 90×human enamel) were divided into six groups (demineralization times of 8/16/24/32/40/48h) of 15 per enamel type and demineralized using a partially saturated lactic acid solution. SMH was measured before and after demineralization and changes in indentation length (ΔIL) calculated. Lesions were characterized using TMR. Data were analyzed (two-way ANOVA) and Pearson correlation coefficients calculated. ΔIL increased with increasing demineralization times but plateaued after 40h, whereas lesion depth (L) and integrated mineral loss (ΔZ) increased almost linearly throughout. No differences between Knoop and Vickers SMH in their ability to measure enamel demineralization were observed as both correlated strongly. Overall, ΔIL correlated strongly with ΔZ and L but only moderately with the degree of surface zone mineralization, whereas ΔZ and L correlated strongly. Bovine demineralized faster than human enamel (all techniques). Lesions in bovine formed faster than in human enamel, although the resulting lesions were almost indistinguishable in their mineral distribution characteristics. Early caries lesion demineralization can be sufficiently studied by SMH, but its limitations on the assessment of the mineral status of more demineralized lesions must be considered. Ideally, complementary techniques to assess changes in both physical and chemical lesion characteristics would be employed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Effect of ultrasonic, sonic and rotating-oscillating powered toothbrushing systems on surface roughness and wear of white spot lesions and sound enamel: An in vitro study.

    Science.gov (United States)

    Hernandé-Gatón, Patrícia; Palma-Dibb, Regina Guenka; Silva, Léa Assed Bezerra da; Faraoni, Juliana Jendiroba; de Queiroz, Alexandra Mussolino; Lucisano, Marília Pacífico; Silva, Raquel Assed Bezerra da; Nelson Filho, Paulo

    2018-04-01

    To evaluate the effect of ultrasonic, sonic and rotating-oscillating powered toothbrushing systems on surface roughness and wear of white spot lesions and sound enamel. 40 tooth segments obtained from third molar crowns had the enamel surface divided into thirds, one of which was not subjected to toothbrushing. In the other two thirds, sound enamel and enamel with artificially induced white spot lesions were randomly assigned to four groups (n=10) : UT: ultrasonic toothbrush (Emmi-dental); ST1: sonic toothbrush (Colgate ProClinical Omron); ST2: sonic toothbrush (Sonicare Philips); and ROT: rotating-oscillating toothbrush (control) (Oral-B Professional Care Triumph 5000 with SmartGuide). The specimens were analyzed by confocal laser microscopy for surface roughness and wear. Data were analyzed statistically by paired t-tests, Kruskal-Wallis, two-way ANOVA and Tukey's post-test (α= 0.05). The different powered toothbrushing systems did not cause a significant increase in the surface roughness of sound enamel (P> 0.05). In the ROT group, the roughness of white spot lesion surface increased significantly after toothbrushing and differed from the UT group (Pspot lesion compared with sound enamel, and this group differed significantly from the ST1 group (Pspot lesion increased surface roughness and wear. None of the powered toothbrushing systems (ultrasonic, sonic and rotating-oscillating) tested caused significant alterations on sound dental enamel. However, conventional rotating-oscillating toothbrushing on enamel with white spot lesion increased surface roughness and wear. Copyright©American Journal of Dentistry.

  20. Caries like lesion initiation in sound enamel following CW CO2 laser irradiation: an in vitro study

    International Nuclear Information System (INIS)

    Nafie, A.; Issam, A.; Ali, M. S. R.

    2005-01-01

    This Study aimed to asses the caries - preventive potential of various CW CO 2 laser parameters, and to explore the effect of the laser power density, and the exposure time on the varies inhibition activity. Materials and Methods: Extracted human premolar teeth were irradiated with three different power densities (7.95, 15.9 and 31.8) W/Cm 2 for three different exposure times (0.2, 0.4 and 0.8) sec of 10.6 μm CW CO 2 laser. All teeth were subjected to caries like lesion formation by 3.5 pH lactic acid for 21 days. The teeth after that were sectioned into ground cross section and the lesion depths were measured using a graticule polarizing microscope. CW CO 2 laser preventive treatments inhibit caries like lesion progression up to 44%. This effect was improved with: (1) Increased power density for each of the three exposure times. (2) Decreased exposure time for each of the three power densities within the limits of the previously listed laser parameters. Conclusion: (1) short exposure time of CW CO 2 laser results in a significant inhibition of the enamel caries like lesion formation. (2) The inhibitory effect depends upon the power density and the exposure time of the laser beam. (3) The optimal CW CO 2 laser parameters used for caries inhibition purpose is achieved with approximately 30 W/Cm 2 power density and 0.2 sec exposure time. (author)

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

    Science.gov (United States)

    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 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.

  2. Demineralization of Enamel in Primary Second Molars Related to Properties of the Enamel

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    N. Sabel

    2012-01-01

    Full Text Available Enamel structure is of importance in demineralization. Differences in porosity in enamel effect the rate of demineralization, seen between permanent and deciduous teeth. Individual differences have been shown in the mean mineral concentration values in enamel, the role of this in demineralization is not thoroughly investigated. The aim of this study was to study variations of depths of artificial lesions of demineralization and to analyze the depth in relation to variations in the chemical and mineral composition of the enamel. A demineralized lesion was created in second primary molars from 18 individuals. Depths of lesions were then related to individual chemical content of the enamel. Enamel responded to demineralization with different lesion depths and this was correlated to the chemical composition. The carbon content in sound enamel was shown to be higher where lesions developed deeper. The lesion was deeper when the degree of porosity of the enamel was higher.

  3. Occurrence and severity of enamel decalcification adjacent to bracket bases and sub-bracket lesions during orthodontic treatment with two different lingual appliances

    Science.gov (United States)

    Klang, Elisabeth; Helms, Hans-Joachim; Wiechmann, Dirk

    2016-01-01

    Summary Background: Using lingual enamel surfaces for bracket placement not only has esthetic advantages, but may also be suitable in terms of reducing frequencies of enamel decalcifications. Objective: To test the null-hypothesis that there is no significant difference in enamel decalcification or cavitation incidence adjacent to and beneath bracket bases between two lingual multi-bracket (MB) appliances that are different in terms of design, material composition, and manufacturing technology (group A: WIN, DW-LingualSystems; group B: Incognito, 3M-Unitek), taking into account patient- and treatment-related variables on white spot lesion (WSL) formation. Methods: Standardized, digital, top-view photographs of 630 consecutive subjects (16214 teeth; n Incognito = 237/6076 teeth; n WIN = 393/10138 teeth; mean age: 17.47±7.8; m/f 43.2/56.8%) with completed lingual MB treatment of the upper and lower permanent teeth 1–7 were screened for decalcification or cavitation adjacent to and beneath the bracket bases before and after treatment, scored from 0 to 7. Non-parametric ANOVA was used for main effects ‘appliance type’, ‘gender’, ‘treatment complexity’, ‘grouped age’ (≤16/>16 years), and ‘treatment duration’ as covariable, at an α-level of 5%. Results: About 2.57% [5.94%] of all teeth in group A [B] developed decalcifications. Subject-related incidence was 9.59% [16.17%] for upper incisors in group A [B], and 12.98% [25.74%] for all teeth 16–46. There were significant effects by gender, age, and treatment duration. Conclusion: The null-hypothesis was rejected: sub-bracket lesions were significantly less frequent in group A, while frequencies of WSL adjacent to brackets were not significantly affected by appliance type. In view of the overall low incidences of lingual post-orthodontic white-spot lesions, the use of lingual appliances is advocated as a valid strategy for a reduction of enamel decalcifications during orthodontic treatment. PMID

  4. A quantitative light microscopic study of the odontoblast and subodontoblastic reactions to active and arrested enamel caries without cavitation

    DEFF Research Database (Denmark)

    Bjørndal, L.; Darvann, T.A.; Thylstrup, Anders

    1998-01-01

    Carious lesions, Computerized histomorphology, Dental pulp, Dentine, Enamel, Microradiography, Odontoblast......Carious lesions, Computerized histomorphology, Dental pulp, Dentine, Enamel, Microradiography, Odontoblast...

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

    Directory of Open Access Journals (Sweden)

    Uwe Kierdorf

    Full Text Available 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.

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

    Science.gov (United States)

    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. Microhardness and Roughness of Infiltrated White Spot Lesions Submitted to Different Challenges.

    Science.gov (United States)

    Neres, É Y; Moda, M D; Chiba, E K; Briso, Alf; Pessan, J P; Fagundes, T C

    A white spot lesion is the first clinical sign of a caries lesion and represents mineral loss from the enamel subsurface. The purpose of this study was to evaluate the microhardness and surface roughness of white spot lesions after application of a resin infiltrant and subjection to different challenges. Caries-like lesions were induced in bovine enamel discs (n=50), and the specimens were randomly divided into five study groups (n=10): demineralized enamel (negative control, G1), infiltrated enamel (G2), infiltrated enamel submitted to brushing (G3), infiltrated enamel submitted to pH cycling (G4), and infiltrated enamel submitted to artificial aging (G5). Half of each enamel surface was used as its own positive control. Roughness data were analyzed using the Kruskal-Wallis test followed by the Dunn test. Results from microhardness were analyzed by two-way analysis of variance, followed by the Tukey test for multiple comparisons. The level of significance was set at 5%. Microhardness and roughness values obtained from the test side of the specimens were significantly lower compared with the sound enamel for all groups. Microhardness values obtained for G2, G3, and G5 were not significantly different. Values found for G1 were significantly lower compared with those for G2, G3, and G5. The lowest microhardness values were observed for G4, which was significantly different from the other groups. Surface roughness was not significantly different between G2 and G3. The resin infiltrant presented superiority over the unprotected white spot lesions, as they were more resistant to mechanical and aging challenges. However, resin infiltration was not able to reestablish the properties of sound enamel and was not resistant to a new cariogenic challenge.

  8. In vitro enamel remineralization capacity of composite resins containing sodium trimetaphosphate and fluoride.

    Science.gov (United States)

    Tiveron, Adelisa Rodolfo Ferreira; Delbem, Alberto Carlos Botazzo; Gaban, Gabriel; Sassaki, Kikue Takebayashi; Pedrini, Denise

    2015-11-01

    This study evaluated the in vitro enamel remineralization capacity of experimental composite resins containing sodium trimetaphosphate (TMP) combined or not with fluoride (F). Bovine enamel slabs were selected upon analysis of initial surface hardness (SH1) and after induction of artificial carious lesions (SH2). Experimental resins were as follows: resin C (control—no sodium fluoride (NaF) or TMP), resin F (with 1.6% NaF), resin TMP (with 14.1% TMP), and resin TMP/F (with NaF and TMP). Resin samples were made and attached to enamel slabs (n = 12 slabs per material). Those specimens (resin/enamel slab) were subjected to pH cycling to promote remineralization, and then final surface hardness (SH3) was measured to calculate the percentage of surface hardness recovery (%SH). The integrated recovery of subsurface hardness (ΔKHN) and F concentration in enamel were also determined. Data was analyzed by ANOVA and Student-Newman-Keuls test (p Resins F and TMP/F showed similar SH3 values (p = 0.478) and %SH (p = 0.336) and differed significantly from the other resins (p resin TMP/F presented the lowest area of lesion (p resins (p = 0.042), but higher than in the other resins (p composite resin enhanced its capacity for remineralization of enamel in vitro. The combination of two agents with action on enamel favored remineralization, suggesting that composite resins containing sodium trimetaphosphate and fluoride could be indicated for clinical procedures in situations with higher cariogenic challenges.

  9. Dynamic measurement of the optical properties of bovine enamel demineralization models using four-dimensional optical coherence tomography

    Science.gov (United States)

    Aden, Abdirahman; Anthony, Arthi; Brigi, Carel; Merchant, Muhammad Sabih; Siraj, Huda; Tomlins, Peter H.

    2017-07-01

    Dental enamel mineral loss is multifactorial and is consequently explored using a variety of in vitro models. Important factors include the presence of acidic pH and its specific ionic composition, which can both influence lesion characteristics. Optical coherence tomography (OCT) has been demonstrated as a promising tool for studying dental enamel demineralization. However, OCT-based characterization and comparison of demineralization model dynamics are challenging without a consistent experimental environment. Therefore, an automated four-dimensional OCT system was integrated with a multispecimen flow cell to measure and compare the optical properties of subsurface enamel demineralization in different models. This configuration was entirely automated, thus mitigating any need to disturb the specimens and ensuring spatial registration of OCT image volumes at multiple time points. Twelve bovine enamel disks were divided equally among three model groups. The model demineralization solutions were citric acid (pH 3.8), acetic acid (pH 4.0), and acetic acid with added calcium and phosphate (pH 4.4). Bovine specimens were exposed to the solution continuously for 48 h. Three-dimensional OCT data were obtained automatically from each specimen at a minimum of 1-h intervals from the same location within each specimen. Lesion dynamics were measured in terms of the depth below the surface to which the lesion extended and the attenuation coefficient. The net loss of surface enamel was also measured for comparison. Similarities between the dynamics of each model were observed, although there were also distinct characteristic differences. Notably, the attenuation coefficients showed a systematic offset and temporal shift with respect to the different models. Furthermore, the lesion depth curves displayed a discontinuous increase several hours after the initial acid challenge. This work demonstrated the capability of OCT to distinguish between different enamel demineralization

  10. Ceramic-like wear behaviour of human dental enamel.

    Science.gov (United States)

    Arsecularatne, J A; Hoffman, M

    2012-04-01

    This paper reports a transmission electron microscopy (TEM) analysis of subsurfaces of enamel specimens following in vitro reciprocating wear tests with an enamel cusp sliding on a flat enamel specimen under hydrated conditions. The obtained results show that crack formation occurred in the wear scar subsurface. The path followed by these cracks seems to be dictated either by the histological structure of enamel or by the contact stress field. Moreover, the analysis of a set of enamel wear results obtained from the literature and application of fracture-based models, originally developed for ceramics, correlate well, confirming the similar wear processes taking place in these materials. This analysis also reveals a marked influence of coefficient of friction on the enamel wear rate: for a higher coefficient of friction value, enamel wear can be severe even under forces generated during normal operation of teeth. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Evaluation of a novel approach in the prevention of white spot lesions around orthodontic brackets.

    Science.gov (United States)

    Yap, J; Walsh, L J; Naser-Ud Din, S; Ngo, H; Manton, D J

    2014-03-01

    The purpose of this study was to evaluate and compare the relative efficacy of a resin fissure sealant, nano-filled self-adhesive protective coating, resin infiltrant, glass ionomer cement (GIC), and GIC containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) in preventing the formation of subsurface lesions of enamel (SLE) adjacent to orthodontic brackets by acting as an enamel surface sealant (ESS). Eighty-five enamel specimens with molar tubes bonded at their centre were randomly divided into five groups, each treated with a different material at the bracket's periphery. Specimens were stored in an acetate demineralization solution at pH 4.5 for 7 days at 37 °C then imaged using quantitative light-induced fluorescence (QLF) to determine the difference in fluorescence (∆F) between sound- and acid-exposed enamel. Lesion cross-sections were then examined using backscattered scanning electron microscopy (SEM) to measure lesion depth. The use of GIC alone or incorporating CPP-ACP significantly reduced ∆F compared with other materials. Backscattered SEM images showed no measurable demineralization for enamel treated with either GIC material in contrast with other groups, which showed statistically significant demineralization levels. The fluoride-releasing effects and CPP-ACP benefits of the GIC materials show promise as an effective ESS in inhibiting enamel demineralization adjacent to orthodontic brackets. © 2014 Australian Dental Association.

  12. Demineralization of Enamel in Primary Second Molars Related to Properties of the Enamel

    OpenAIRE

    Sabel, N.; Robertson, A.; Nietzsche, S.; Norén, J. G.

    2012-01-01

    Enamel structure is of importance in demineralization. Differences in porosity in enamel effect the rate of demineralization, seen between permanent and deciduous teeth. Individual differences have been shown in the mean mineral concentration values in enamel, the role of this in demineralization is not thoroughly investigated. The aim of this study was to study variations of depths of artificial lesions of demineralization and to analyze the depth in relation to variations in the chemical an...

  13. Potential of sub-ablative pulsed CO2 laser irradiation on inhibition of artificial caries-like lesion progress in bovine dental enamel

    International Nuclear Information System (INIS)

    Oliveira, Marcella Esteves

    2005-01-01

    The aim of this study was to investigate whether sub-ablative pulsed C0 2 laser (1 0,6 μm) irradiation is capable of reducing the susceptibility of the dental enamel to demineralization, and thus achieving a potential caries-protective effect. The crowns of 51 bovine front teeth, embedded in acrylic resin and polished until exposure of flat enamel surface, were used. The samples were cut in cubes of 10x10 mm, and totally coated with acid-resistant nail varnish, except for an enamel exposed window of 16 mm square. Three groups (n=17) were obtained: control group (CG) not irradiated; group laser A (LA) and group laser B (LB) where the samples were irradiated. The conditions were 60 mJ, 100 Hz, 0,3 J/cm 2 for LA and 135 mJ, 10 Hz, 0,7 J/cm 2 for LB. Two samples of each group were submitted to SEM analysis and fifteen to demineralization in 3 ml acetate buffer solution (0,1 mol/L) with pH 4,5 for 24h at 37 deg C, with regular agitation. After the specimens were removed from the solution, the calcium and phosphorous content were measured with an inductively coupled plasma optical emission spectrometer and 2 more samples of each were submitted to SEM analysis. The obtained Ca and P means in μg/ml and the calculated Ca/P molar ratio were: CG (367,88 ± 33,47; 168,91 ± 14,55; 1,70 ± 0,07) ; LA (372,70 ± 41,70; 161,46 ± 15,26; 1,79 ± 0,07) and LB (328,87 ± 24,91; 145,02 ± 11,04; 1,77 ± 0,05). The ANOVA statistical test revealed statistically significant difference for [Ca], [P] e Ca/P content between the groups (p 2 pulsed CO 2 laser irradiation of bovine enamel was capable of reducing the enamel acid solubility without causing damage to the surface and therefore is a potential method of caries prevention. (author)

  14. Natural enamel caries in polarized light microscopy: differences in histopathological features derived from a qualitative versus a quantitative approach to interpret enamel birefringence.

    Science.gov (United States)

    De Medeiros, R C G; Soares, J D; De Sousa, F B

    2012-05-01

    Lesion area measurement of enamel caries using polarized light microscopy (PLM) is currently performed in a large number of studies, but measurements are based mainly on a mislead qualitative interpretation of enamel birefringence in a single immersion medium. Here, five natural enamel caries lesions are analysed by microradiography and in PLM, and the differences in their histopathological features derived from a qualitative versus a quantitative interpretation of enamel birefringence are described. Enamel birefringence in different immersion media (air, water and quinoline) is interpreted by both qualitative and quantitative approaches, the former leading to an underestimation of the depth of enamel caries mainly when the criterion of validating sound enamel as a negatively birefringent area in immersion in water is used (a current common practice in dental research). Procedures to avoid the shortcomings of a qualitative interpretation of enamel birefringence are presented and discussed. © 2012 The Authors Journal of Microscopy © 2012 Royal Microscopical Society.

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

    International Nuclear Information System (INIS)

    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

  16. Comparative evaluation of Nano-hydroxyapatite and casein Phosphopeptide-amorphous calcium phosphate on the remineralization potential of early enamel lesions: An in vitro study

    Directory of Open Access Journals (Sweden)

    Anshul Sharma

    2017-01-01

    Full Text Available Background: Benefits of remineralizing agents in a wide variety of formulations have been proved beneficial in caries management. Casein phosphopeptide-amorphous calcium phosphate (CPP–ACP nanocomplex has been recommended and used as remineralizing agent. Nano-hydroxyapatite (n-HAp is one of the most biocompatible and bioactive material having wide range of application in dentistry, but does it excel better compared to CPP-ACP. Aims: To evaluate and compare the remineralizing efficiency of the paste containing hydroxyapatite and casein phosphopeptide-amorphous calcium phosphate. Settings and Design: The study was an in vitro single blinded study with lottery method of randomization approved by the Institutional Ethics Committee. Materials and methods: 30 non carious premolar teeth. The teeth were demineralized and divided into 2 groups and subjected to remineralization. The samples were analysed for surface hardness and mineral content. Statistical Analysis: Student t’ test and repeated measures of ANOVA was applied. Results: Average hardness in Nano-hydroxyapatite group increased to 340 ± 31.70 SD and 426 ± 50.62 SD for 15 and 30 days respectively and that of (CPP–ACP, 355.83 ± 38.55 SD and 372.67 ± 53.63 SD. The change in the hardness values was not statistically significant with P value of 0.39 (P > 0.05. Calcium and Phosphorous levels increased in both the groups but was not significant. Conclusion: Both the agents used are effective in causing remineralization of enamel. Nano-hydroxyapatite is more effective as compared to Casein phosphopeptide-amorphous calcium phosphate, in increasing the Calcium and Phosphorus content of enamel, and this effect is more evident over a longer treatment period. Key Message: Remineralizing agents are a boon for caries management. With the advent of many formulations it is difficult to clinically select the agent. This study compares the remineralizing potential of Casein

  17. Comparing natural and artificial carious lesions in human crowns by means of conventional hard x-ray micro-tomography and two-dimensional x-ray scattering with synchrotron radiation

    Science.gov (United States)

    Botta, Lea Maria; White, Shane N.; Deyhle, Hans; Dziadowiec, Iwona; Schulz, Georg; Thalmann, Peter; Müller, Bert

    2016-10-01

    Dental caries, one of the most prevalent infectious bacterial diseases in the world, is caused by specific types of acid-producing bacteria. Caries is a disease continuum resulting from the earliest loss of ions from apatite crystals through gross cavitation. Enamel dissolution starts when the pH-value drops below 5.5. Neutralizing the pH-value in the oral cavity opposes the process of demineralization, and so caries lesions occur in a dynamic cyclic de-mineralizing/remineralizing environment. Unfortunately, biomimetic regeneration of cavitated enamel is not yet possible, although remineralization of small carious lesions occurs under optimal conditions. Therefore, the development of methods that can regenerate carious lesions, and subsequently recover and retain teeth, is highly desirable. For the present proceedings we analyzed one naturally occurring sub-surface and one artificially produced lesion. For the characterization of artificial and natural lesions micro computed tomography is the method of choice when looking to determine three-dimensional mineral distribution and to quantify the degree of mineralization. In this pilot study we elucidate that the de-mineralized enamel in natural and artificially induced lesions shows comparable X-ray attenuation behavior, thereby implying that the study protocol employed herein seems to be appropriate. Once we know that the lesions are comparable, a series of well-reproducible in vitro experiments on enamel regeneration could be performed. In order to quantify further lesion morphology, the anisotropy of the enamel's nanostructure can be characterized by using spatially resolved, small-angle X-ray scattering. We wanted to demonstrate that the artificially induced defect fittingly resembles the natural carious lesion.

  18. Amelogenin and Enamel Biomimetics

    Science.gov (United States)

    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

  19. Optical coherence tomography use in the diagnosis of enamel defects

    Science.gov (United States)

    Al-Azri, Khalifa; Melita, Lucia N.; Strange, Adam P.; Festy, Frederic; Al-Jawad, Maisoon; Cook, Richard; Parekh, Susan; Bozec, Laurent

    2016-03-01

    Molar incisor hypomineralization (MIH) affects the permanent incisors and molars, whose undermineralized matrix is evidenced by lesions ranging from white to yellow/brown opacities to crumbling enamel lesions incapable of withstanding normal occlusal forces and function. Diagnosing the condition involves clinical and radiographic examination of these teeth, with known limitations in determining the depth extent of the enamel defects in particular. Optical coherence tomography (OCT) is an emerging hard and soft tissue imaging technique, which was investigated as a new potential diagnostic method in dentistry. A comparison between the diagnostic potential of the conventional methods and OCT was conducted. Compared to conventional imaging methods, OCT gave more information on the structure of the enamel defects as well as the depth extent of the defects into the enamel structure. Different types of enamel defects were compared, each type presenting a unique identifiable pattern when imaged using OCT. Additionally, advanced methods of OCT image analysis including backscattered light intensity profile analysis and enface reconstruction were performed. Both methods confirmed the potential of OCT in enamel defects diagnosis. In conclusion, OCT imaging enabled the identification of the type of enamel defect and the determination of the extent of the enamel defects in MIH with the advantage of being a radiation free diagnostic technique.

  20. Endocytosis and Enamel Formation

    Directory of Open Access Journals (Sweden)

    Cong-Dat Pham

    2017-07-01

    Full Text Available Enamel formation requires consecutive stages of development to achieve its characteristic extreme mineral hardness. Mineralization depends on the initial presence then removal of degraded enamel proteins from the matrix via endocytosis. The ameloblast membrane resides at the interface between matrix and cell. Enamel formation is controlled by ameloblasts that produce enamel in stages to build the enamel layer (secretory stage and to reach final mineralization (maturation stage. Each stage has specific functional requirements for the ameloblasts. Ameloblasts adopt different cell morphologies during each stage. Protein trafficking including the secretion and endocytosis of enamel proteins is a fundamental task in ameloblasts. The sites of internalization of enamel proteins on the ameloblast membrane are specific for every stage. In this review, an overview of endocytosis and trafficking of vesicles in ameloblasts is presented. The pathways for internalization and routing of vesicles are described. Endocytosis is proposed as a mechanism to remove debris of degraded enamel protein and to obtain feedback from the matrix on the status of the maturing enamel.

  1. Effect of caries infiltration technique and fluoride therapy on the colour masking of white spot lesions.

    Science.gov (United States)

    Rocha Gomes Torres, Carlos; Borges, Alessandra Buhler; Torres, Luciana Marcondes Sarmento; Gomes, Isabela Silva; de Oliveira, Rodrigo Simões

    2011-03-01

    A carious lesion is initiated through the subsurface demineralization of enamel, and presents clinically as a white spot, interfering with the aesthetics. This lesion should not receive restorative treatment because it is capable of remineralization. The aim of this study was to evaluate the performance of different treatments on masking white spot lesions by assessing the colour change. Artificial white spot lesions were produced in bovine enamel of 60 cylindrical-shaped samples. The samples were randomly divided into four groups: CON (control) - immersion in artificial saliva; DF - daily application of 0.05% fluoride solution; WF - weekly application of 2% fluoride gel; and IC - resin infiltration (Icon(®) - DMG). The assessment of colour was performed by a spectrophotometer in four distinct stages: baseline, after the production of artificial caries; after 4 weeks; after 8 weeks; and after a new acid challenge. The ΔL values were calculated at each stage in relation to the baseline colour. The application of RM ANOVA revealed significant differences between the factors' treatment and time (p=0.001). For the interaction between factors there were no significant differences (p=0.27). The Tukey's test (pwhite spot lesions. Also, after a new acid challenge, the group infiltrated with low viscosity resin presented the lowest means of colour change. Copyright © 2011. Published by Elsevier Ltd.

  2. Enamel surface remineralization: Using synthetic nanohydroxyapatite

    Directory of Open Access Journals (Sweden)

    J Shanti Swarup

    2012-01-01

    Full Text Available Objective: The purpose of this study was to evaluate the effects of synthetically processed hydroxyapatite particles in remineralization of the early enamel lesions in comparison with 2% sodium fluoride. Materials and Methods: Thirty sound human premolars were divided into nanohydroxyapatite group (n0 = 15 and the sodium fluoride group (n = 15. The specimens were subjected to demineralization before being coated with 10% aqueous slurry of 20 nm nanohydroxyapatite or 2% sodium fluoride. The remineralizing efficacy of the materials was evaluated using surface microhardness (SMH measurements, scanning microscopic analysis and analysis of the Ca/P ratio of the surface enamel. Data analysis was carried out using paired t-test and independent t-test. Results: The results showed that the nanohydroxyapatite group produced a surface morphology close to the biologic enamel, the increase in mineral content (Ca/P ratio was more significant in the nanohydroxyapatite group ( P 0.05. Conclusion: The use of biomimetic nanohydroxyapatite as a remineralizing agent holds promise as a new synthetic enamel biocompatible material to repair early carious lesions.

  3. Structural, mechanical and chemical evaluation of molar-incisor hypomineralization-affected enamel: A systematic review.

    Science.gov (United States)

    Elhennawy, Karim; Manton, David John; Crombie, Felicity; Zaslansky, Paul; Radlanski, Ralf J; Jost-Brinkmann, Paul-Georg; Schwendicke, Falk

    2017-11-01

    To systematically assess and contrast reported differences in microstructure, mineral density, mechanical and chemical properties between molar-incisor-hypomineralization-affected (MIH) enamel and unaffected enamel. Studies on extracted human teeth, clinically diagnosed with MIH, reporting on the microstructure, mechanical properties or the chemical composition and comparing them to unaffected enamel were reviewed. Electronic databases (PubMed, Embase and Google Scholar) were screened; hand searches and cross-referencing were also performed. Twenty-two studies were included. Fifteen studies on a total of 201 teeth investigated the structural properties, including ten (141 teeth) on microstructure and seven (60 teeth) on mineral density; six (29 teeth) investigated the mechanical properties and eleven (87 teeth) investigated the chemical properties of MIH-affected enamel and compared them to unaffected enamel. Studies unambiguously found a reduction in mineral quantity and quality (reduced Ca and P content), reduction of hardness and modulus of elasticity (also in the clinically sound-appearing enamel bordering the MIH-lesion), an increase in porosity, carbon/carbonate concentrations and protein content compared to unaffected enamel. were ambiguous with regard to the extent of the lesion through the enamel to the enamel-dentin junction, the Ca/P ratio and the association between clinical appearance and defect severity. There is an understanding of the changes related to MIH-affected enamel. The association of these changes with the clinical appearance and resulting implications for clinical management are unclear. MIH-affected enamel is greatly different from unaffected enamel. This has implications for management strategies. The possibility of correlating the clinical appearance of MIH-affected enamel with the severity of enamel changes and deducing clinical concepts (risk stratification etc.) is limited. Crown Copyright © 2017. Published by Elsevier Ltd. All

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

    Science.gov (United States)

    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.

  5. Protein- mediated enamel mineralization

    Science.gov (United States)

    Moradian-Oldak, Janet

    2012-01-01

    Enamel is a hard nanocomposite bioceramic with significant resilience that protects the mammalian tooth from external physical and chemical damages. The remarkable mechanical properties of enamel are associated with its hierarchical structural organization and its thorough connection with underlying dentin. This dynamic mineralizing system offers scientists a wealth of information that allows the study of basic principals of organic matrix-mediated biomineralization and can potentially be utilized in the fields of material science and engineering for development and design of biomimetic materials. This chapter will provide a brief overview of enamel hierarchical structure and properties as well as the process and stages of amelogenesis. Particular emphasis is given to current knowledge of extracellular matrix protein and proteinases, and the structural chemistry of the matrix components and their putative functions. The chapter will conclude by discussing the potential of enamel for regrowth. PMID:22652761

  6. Development of fluorapatite cement for dental enamel defects repair.

    Science.gov (United States)

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

    2011-06-01

    In order to restore the badly carious lesion of human dental enamel, a crystalline paste of fluoride substituted apatite cement was synthesized by using the mixture of tetracalcium phosphate (TTCP), dicalcium phosphate anhydrous (DCPA) and ammonium fluoride. The apatite cement paste could be directly filled into the enamel defects (cavities) to repair damaged dental enamel. The results indicated that the hardened cement was fluorapatite [Ca(10)(PO(4))(6)F(2), FA] with calcium to phosphorus atom molar ratio (Ca/P) of 1.67 and Ca/F ratio of 5. The solubility of FA cement in Tris-HCl solution (pH = 5) was slightly lower than the natural enamel, indicating the FA cement was much insensitive to the weakly acidic solutions. The FA cement was tightly combined with the enamel surface, and there was no obvious difference of the hardness between the FA cement and natural enamel. The extracts of FA cement caused no cytotoxicity on L929 cells, which satisfied the relevant criterion on dental biomaterials, revealing good cytocompatibility. In addition, the results showed that the FA cement had good mechanical strength, hydrophilicity, and anti-bacterial adhesion properties. The study suggested that using FA cement was simple and promising approach to effectively and conveniently restore enamel defects.

  7. Subsurface probing

    International Nuclear Information System (INIS)

    Lytle, R.J.

    1978-01-01

    Imaging techniques that can be used to translate seismic and electromagnetic wave signals into visual representation are briefly discussed. The application of these techniques is illustrated on the example of determining the subsurface structure of a proposed power plant. Imaging makes the wave signals intelligible to the non-geologists. R and D work needed in this area are tabulated

  8. Dentist and practice characteristics associated with restorative treatment of enamel caries in permanent teeth

    DEFF Research Database (Denmark)

    Fellows, Jeffrey L; Gordan, Valeria V; Gilbert, Gregg H

    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. Actual clinical data were used to evaluate patient, dentist, and practice...... characteristics associated with restoration of enamel caries, while accounting for other factors. METHODS: 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 were combined. ANOVA 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...

  9. STUDY ON THE EFFECTS OF ACID ETCHING ON AFFECTED ENAMEL

    Directory of Open Access Journals (Sweden)

    Simona Stoleriu

    2011-12-01

    Full Text Available The purpose of the study was to establish and compare the effects of ortophosphoric and hydrochloric acids on the enamel affected by incipient carious lesions with different evolution. Materials and method. 20 teeth with acute and chronic non-cavitary carious lesions were considered for the study. The teeth were sectioned in two halves through the middle of the non-cavitary lesions. The halves of 5 white spot-type lesions and of 5 brown spot-type ones were analyzed as to their surface roughness, on an atomic force microscope (AFM. 5 halves with white spot-type lesions and 5 halves with brown spot-type ones were subjected to acid etching with 37% ortophosphoric acid (Scotchbond etchant gel, 3M ESPE, and an equal number of samples was subjected to the action of 15% hydrochloric acid (ICON-etch, DMG Dental Products Ltd for 2 min, then washed with water and analyzed by AFM. Results. The initial surface roughness of the enamel was higher in the white spot–type carious lesions, comparatively with the brown spot-type ones. For both types of carious non-cavitary lesions, acid etching with phosphoric and hydrochloric acid significantly increased the surface roughness of the enamel, comparatively with the status of the enamel surface prior to etching. The hydrochloric acid led to a surface roughness significantly higher than in the case of ortophosphoric acid, in both acute and chronic non-cavitary carious lesions. The roughness values obtained through etching with ortophosphoric and hydrochloric acid were higher in the white spot-type carious lesions, comparatively with the brown spot-type ones. Conclusions. Both the 37% ortophosphoric acid and the 15% hydrochloric acid determined a significantly higher surface roughness of the enamel affected by acute and chronic non-cavitary carious lesions. The surface condition of the brown spot-type carious lesions was less significantly modified, comparatively with that of the white spot-type lesions, by the

  10. Optical Assessment of Caries Lesion Structure and Activity

    Science.gov (United States)

    Lee, Robert Chulsung

    New, more sophisticated diagnostic tools are needed for the detection and characterization of caries lesions in the early stages of development. It is not sufficient to simply detect caries lesions, methods are needed to assess the activity of the lesion and determine if chemical or surgical intervention is needed. Previous studies have demonstrated that polarization sensitive optical coherence tomography (PS-OCT) can be used to nondestructively image the subsurface lesion structure and measure the thickness of the highly mineralized surface zone. Other studies have demonstrated that the rate of dehydration can be correlated with the lesion activity and that the rate can be measured using optical methods. The main objective of this work was to test the hypothesis that optical methods can be used to assess lesion activity on tooth coronal and root surfaces. Simulated caries models were used to develop and validate an algorithm for detecting and measuring the highly mineralized surface layer using PS-OCT. This work confirmed that the algorithm was capable of estimating the thickness of the highly mineralized surface layer with high accuracy. Near-infrared (NIR) reflectance and thermal imaging methods were used to assess activity of caries lesions by measuring the state of lesion hydration. NIR reflectance imaging performed the best for artificial enamel and natural coronal caries lesion samples, particularly at wavelengths coincident with the water absorption band at 1460-nm. However, thermal imaging performed the best for artificial dentin and natural root caries lesion samples. These novel optical methods outperformed the conventional methods (ICDAS II) in accurately assessing lesion activity of natural coronal and root caries lesions. Infrared-based imaging methods have shown potential for in-vivo applications to objectively assess caries lesion activity in a single examination. It is likely that if future clinical trials are a success, this novel imaging

  11. Enamel formation and amelogenesis imperfecta.

    Science.gov (United States)

    Hu, Jan C-C; Chun, Yong-Hee P; Al Hazzazzi, Turki; Simmer, James P

    2007-01-01

    Dental enamel is the epithelial-derived hard tissue covering the crowns of teeth. It is the most highly mineralized and hardest tissue in the body. Dental enamel is acellular and has no physiological means of repair outside of the protective and remineralization potential provided by saliva. Enamel is comprised of highly organized hydroxyapatite crystals that form in a defined extracellular space, the contents of which are supplied and regulated by ameloblasts. The entire process is under genetic instruction. The genetic control of amelogenesis is poorly understood, but requires the activities of multiple components that are uniquely important for dental enamel formation. Amelogenesis imperfecta (AI) is a collective designation for the variety of inherited conditions displaying isolated enamel malformations, but the designation is also used to indicate the presence of an enamel phenotype in syndromes. Recently, genetic studies have demonstrated the importance of genes encoding enamel matrix proteins in the etiology of isolated AI. Here we review the essential elements of dental enamel formation and the results of genetic analyses that have identified disease-causing mutations in genes encoding enamel matrix proteins. In addition, we provide a fresh perspective on the roles matrix proteins play in catalyzing the biomineralization of dental enamel. Copyright 2007 S. Karger AG, Basel.

  12. Effect of Galla chinensis on enhancing remineralization of enamel crystals

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Lei; Huang Shengbin [State Key Laboratory of Oral Disease, Sichuan University, Chengdu (China); Li Jiyao; Zhou Xuedong, E-mail: stonedentist@yahoo.c [West China College of Stomatology, Sichuan University, Chengdu (China)

    2009-06-15

    The aim of this scanning electron microscopy (SEM) study was to investigate the effect of chemical compounds of Galla chinensis (GCE, gallic acid) on the remineralization of enamel crystals in vitro. Bovine enamel blocks with an in vitro produced initial lesion were used. The lesions were subjected to a pH-cycling regime for 12 days. Each daily cycle included 4 x 1 min applications with one of six treatments: group A: 1000 ppm F aq. (as NaF, positive control); group B: deionized water (DDW, negative control); group C: 4000 ppm crude aqueous extract of GCE; group D: 4000 ppm gallic acid; group E: 4000 ppm GCE with 1000 ppm F; group F: 4000 ppm gallic acid with 1000 ppm F. The surface and vertical section of the enamel lesions were analyzed by SEM. The results indicated that the chemical compounds of G. chinensis could regulate the de-/remineralization balance through influencing the morphology and structure of enamel crystals, and the mechanisms seem to be different for GCE and gallic acid.

  13. Effect of Galla chinensis on enhancing remineralization of enamel crystals

    International Nuclear Information System (INIS)

    Cheng Lei; Huang Shengbin; Li Jiyao; Zhou Xuedong

    2009-01-01

    The aim of this scanning electron microscopy (SEM) study was to investigate the effect of chemical compounds of Galla chinensis (GCE, gallic acid) on the remineralization of enamel crystals in vitro. Bovine enamel blocks with an in vitro produced initial lesion were used. The lesions were subjected to a pH-cycling regime for 12 days. Each daily cycle included 4 x 1 min applications with one of six treatments: group A: 1000 ppm F aq. (as NaF, positive control); group B: deionized water (DDW, negative control); group C: 4000 ppm crude aqueous extract of GCE; group D: 4000 ppm gallic acid; group E: 4000 ppm GCE with 1000 ppm F; group F: 4000 ppm gallic acid with 1000 ppm F. The surface and vertical section of the enamel lesions were analyzed by SEM. The results indicated that the chemical compounds of G. chinensis could regulate the de-/remineralization balance through influencing the morphology and structure of enamel crystals, and the mechanisms seem to be different for GCE and gallic acid.

  14. Hipoplasia Enamel Pada Penderita Penyakit Eksantema

    OpenAIRE

    Dewi saputri

    2008-01-01

    Hipoplasia enamel merupakan gangguan pada masa pemhentukan matriks organik yang menyebabkan gangguan struktur pada enamel sehingga secara klinis terlihat pada suatu bagian dari gigi tidak terbentuk enamel dan kadang-kadang sama sekali tidak terbentuk enamel, serta diikuti dengan perubahan warna pada gigi. Dikenal berbagai faktor penyebab hipoplasia enamel, salah satunya adalah penyakit eksantema yaitu menyebabkan infeksi pada bayi dan anak-anak. Gambaran histopatologis hipoplasia enamel adala...

  15. Microstructure of enamel.

    Science.gov (United States)

    Boyde, A

    1997-01-01

    Enamel is a composite material consisting of mineral and organic phases. The properties of the mineral phase are modulated dramatically by its division into microscopic crystals, cemented together by the organic matrix protein polymer. A good concept of the 3D orientations of the crystals derives from visualizing their growth perpendicular to the surface in which they develop, which is pitted by the secretory poles of the ameloblasts. The arrangement of the crystals is the cause of the discontinuities, known as the prism boundaries or junctions, in the otherwise continuous structure. These locations acquire a more concentrated organic matrix during maturation, and they are both crack stoppers and crack propagation tracks in the adult tissue. Any tendency of prisms to cleave may be reduced by their varicosities, which reflect daily variations in the rate of production; their cross-sectional shape; the non-parallelism of adjacent groups, which develops through translocation of groups of cells across the surface during development; and the support of any one microscopic tissue element by other tissue, including dentine, placed to resist an applied load. Incremental growth lines are preferential cleavage planes within the enamel. Failure patterns of enamel in normal and abnormal use can be explained by these parameters, with additional consideration of functional variation and fatigue.

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

    Science.gov (United States)

    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

  17. Bicarbonate Transport During Enamel Maturation.

    Science.gov (United States)

    Yin, Kaifeng; Paine, Michael L

    2017-11-01

    Amelogenesis (tooth enamel formation) is a biomineralization process consisting primarily of two stages (secretory stage and maturation stage) with unique features. During the secretory stage, the inner epithelium of the enamel organ (i.e., the ameloblast cells) synthesizes and secretes enamel matrix proteins (EMPs) into the enamel space. The protein-rich enamel matrix forms a highly organized architecture in a pH-neutral microenvironment. As amelogenesis transitions to maturation stage, EMPs are degraded and internalized by ameloblasts through endosomal-lysosomal pathways. Enamel crystallite formation is initiated early in the secretory stage, however, during maturation stage the more rapid deposition of calcium and phosphate into the enamel space results in a rapid expansion of crystallite length and mineral volume. During maturation-stage amelogenesis, the pH value of enamel varies considerably from slightly above neutral to acidic. Extracellular acid-base balance during enamel maturation is tightly controlled by ameloblast-mediated regulatory networks, which include significant synthesis and movement of bicarbonate ions from both the enamel papillary layer cells and ameloblasts. In this review we summarize the carbonic anhydrases and the carbonate transporters/exchangers involved in pH regulation in maturation-stage amelogenesis. Proteins that have been shown to be instrumental in this process include CA2, CA6, CFTR, AE2, NBCe1, SLC26A1/SAT1, SLC26A3/DRA, SLC26A4/PDS, SLC26A6/PAT1, and SLC26A7/SUT2. In addition, we discuss the association of miRNA regulation with bicarbonate transport in tooth enamel formation.

  18. Contact fatigue of human enamel: Experiments, mechanisms and modeling.

    Science.gov (United States)

    Gao, S S; An, B B; Yahyazadehfar, M; Zhang, D; Arola, D D

    2016-07-01

    Cyclic contact between natural tooth structure and engineered ceramics is increasingly common. Fatigue of the enamel due to cyclic contact is rarely considered. The objectives of this investigation were to evaluate the fatigue behavior of human enamel by cyclic contact, and to assess the extent of damage over clinically relevant conditions. Cyclic contact experiments were conducted using the crowns of caries-free molars obtained from young donors. The cuspal locations were polished flat and subjected to cyclic contact with a spherical indenter of alumina at 2Hz. The progression of damage was monitored through the evolution in contact displacement, changes in the contact hysteresis and characteristics of the fracture pattern. The contact fatigue life diagram exhibited a decrease in cycles to failure with increasing cyclic load magnitude. Two distinct trends were identified, which corresponded to the development and propagation of a combination of cylindrical and radial cracks. Under contact loads of less than 400N, enamel rod decussation resisted the growth of subsurface cracks. However, at greater loads the damage progressed rapidly and accelerated fatigue failure. Overall, cyclic contact between ceramic appliances and natural tooth structure causes fatigue of the enamel. The extent of damage is dependent on the magnitude of cyclic stress and the ability of the decussation to arrest the fatigue damage. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Fluoride varnishes and enamel caries

    NARCIS (Netherlands)

    Bruyn, Hugo de

    1987-01-01

    Topical fluoride applications have the aim of increasing the fluoride uptake in enamel and consequently reducing caries. In the early ‘60s fluoride varnishes were introduced because they had a long contact period with the enamel which resulted in a higher fluoride uptake than from other topical

  20. Silicate enamel for alloyed steel

    International Nuclear Information System (INIS)

    Ket'ko, K.K.

    1976-01-01

    The use of silicate enamels in the metallurgical industry is discussed. Presented are the composition and the physico-chemical properties of the silicate enamel developed at the factory 'Krasnyj Oktyabr'. This enamel can be used in the working conditions both in the liquid and the solid state. In so doing the enamel is melted at 1250 to 1300 deg C, granulated and then reduced to a fraction of 0.3 to 0.5 mm. The greatest homogeneity is afforded by a granulated enamel. The trials have shown that the conversion of the test ingots melted under a layer of enamel leads to the smaller number of the ingots rejected for surface defect reasons and the lower metal consumption for slab cleaning. The cost of the silicate enamel is somewhat higher than that of synthetic slags but its application to the melting of stainless steels is still economically beneficial and technologically reasonable. Preliminary calculations only for steel EhI4IEh have revealed that the use of this enamel saves annually over 360000 roubles [ru

  1. Morphology and fracture of enamel.

    Science.gov (United States)

    Myoung, Sangwon; Lee, James; Constantino, Paul; Lucas, Peter; Chai, Herzl; Lawn, Brian

    2009-08-25

    This study examines the inter-relation between enamel morphology and crack resistance by sectioning extracted human molars after loading to fracture. Cracks appear to initiate from tufts, hypocalcified defects at the enamel-dentin junction, and grow longitudinally around the enamel coat to produce failure. Microindentation corner cracks placed next to the tufts in the sections deflect along the tuft interfaces and occasionally penetrate into the adjacent enamel. Although they constitute weak interfaces, the tufts are nevertheless filled with organic matter, and appear to be stabilized against easy extension by self-healing, as well as by mutual stress-shielding and decussation, accounting at least in part for the capacity of tooth enamel to survive high functional forces.

  2. Mechanical characterization of enamel coated steel bars.

    Science.gov (United States)

    2012-12-01

    In this study, the corrosion process of enamel-coated deformed rebar completely immersed in 3.5 wt.% NaCl solution was evaluated : over a period of 84 days by EIS testing. Three types of enamel coating were investigated: pure enamel, 50/50 enamel coa...

  3. In Vitro Inhibition of Enamel Demineralisation by Fluoride-releasing Restorative Materials and Dental Adhesives.

    Science.gov (United States)

    Dionysopoulos, Dimitrios; Koliniotou-Koumpia, Eugenia; Helvatzoglou-Antoniades, Maria; Kotsanos, Nikolaos

    2016-01-01

    To determine the ability of 5 contemporary fluoride-releasing restoratives and 3 fluoride-releasing adhesives to inhibit enamel demineralisation surrounding restorations, and the associations between inhibition and the levels of fluoride released from these materials. Five fluoride-releasing restoratives (Fuji IX GP, Ketac N100, Dyract Extra, Beautifil II and Wave) and 3 fluoride-releasing adhesives (Stae, Prime & Bond NT and Fluoro Bond II) were investigated. Eight disks of each material were prepared. Fluoride release was measured daily using a fluoride-ion-selective electrode for 15 days. Twenty-four cavities for each group were restored with a restorative and an adhesive. Specimens were subjected to thermal stress and stored for 30 days in saline solution. After a 15-day pH-cycling regimen, two 150-μm-thick sections were derived from each specimen. Enamel lesion depth was measured at 0, 100, and 200 μm from each restoration's margin via polarised light microscopy. Of the restoratives investigated, Fuji IX GP released the most fluoride. The fluoride-releasing restoratives tested exhibited shallower enamel lesions than did the control group at all distances tested (p < 0.05). Fuji IX GP yielded significantly lower enamel lesion depth than did the other experimental materials. The depths of enamel lesions did not differ significantly when comparing restoratives applied with a fluoride-releasing adhesive with those applied with a non-fluoride-releasing adhesive. The fluoride-releasing materials tested reduced enamel demineralisation but to different extents, depending on their levels of fluoride release. Fluoride-releasing adhesives did not influence enamel lesion formation.

  4. Photoacoustic imaging of teeth for dentine imaging and enamel characterization

    Science.gov (United States)

    Periyasamy, Vijitha; Rangaraj, Mani; Pramanik, Manojit

    2018-02-01

    Early detection of dental caries, cracks and lesions is needed to prevent complicated root canal treatment and tooth extraction procedures. Resolution of clinically used x-ray imaging is low, hence optical imaging techniques such as optical coherence tomography, fluorescence imaging, and Raman imaging are widely experimented for imaging dental structures. Photoacoustic effect is used in photon induced photoacoustic streaming technique to debride the root canal. In this study, the extracted teeth were imaged using photoacoustic tomography system at 1064 nm. The degradation of enamel and dentine is an indicator of onset of dental caries. Photoacoustic microscopy (PAM) was used to study the tooth enamel. Images were acquired using acoustic resolution PAM system. This was done to identify microscopic cracks and dental lesion at different anatomical sites (crown and cementum). The PAM tooth profile is an indicator of calcium distribution which is essential for demineralization studies.

  5. Novel hydroxyapatite nanorods improve anti-caries efficacy of enamel infiltrants.

    Science.gov (United States)

    Andrade Neto, D M; Carvalho, E V; Rodrigues, E A; Feitosa, V P; Sauro, S; Mele, G; Carbone, L; Mazzetto, S E; Rodrigues, L K; Fechine, P B A

    2016-06-01

    Enamel resin infiltrants are biomaterials able to treat enamel caries at early stages. Nevertheless, they cannot prevent further demineralization of mineral-depleted enamel. Therefore, the aim of this work was to synthesize and incorporate specific hydroxyapatite nanoparticles (HAps) into the resin infiltrant to overcome this issue. HAps were prepared using a hydrothermal method (0h, 2h and 5h). The crystallinity, crystallite size and morphology of the nanoparticles were characterized through XRD, FT-IR and TEM. HAps were then incorporated (10wt%) into a light-curing co-monomer resin blend (control) to create different resin-based enamel infiltrants (HAp-0h, HAp-2h and HAp-5h), whose degree of conversion (DC) was assessed by FT-IR. Enamel caries lesions were first artificially created in extracted human molars and infiltrated using the tested resin infiltrants. Specimens were submitted to pH-cycling to simulate recurrent caries. Knoop microhardness of resin-infiltrated underlying and surrounding enamel was analyzed before and after pH challenge. Whilst HAp-0h resulted amorphous, HAp-2h and HAp-5h presented nanorod morphology and higher crystallinity. Resin infiltration doped with HAp-2h and HAp-5h caused higher enamel resistance against demineralization compared to control HAp-free and HAp-0h infiltration. The inclusion of more crystalline HAp nanorods (HAp-2h and HAp-5h) increased significantly (p<0.05) the DC. Incorporation of more crystalline HAp nanorods into enamel resin infiltrants may be a feasible method to improve the overall performance in the prevention of recurrent demineralization (e.g. caries lesion) in resin-infiltrated enamel. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Three-dimensional primate molar enamel thickness.

    Science.gov (United States)

    Olejniczak, Anthony J; Tafforeau, Paul; Feeney, Robin N M; Martin, Lawrence B

    2008-02-01

    Molar enamel thickness has played an important role in the taxonomic, phylogenetic, and dietary assessments of fossil primate teeth for nearly 90 years. Despite the frequency with which enamel thickness is discussed in paleoanthropological discourse, methods used to attain information about enamel thickness are destructive and record information from only a single plane of section. Such semidestructive planar methods limit sample sizes and ignore dimensional data that may be culled from the entire length of a tooth. In light of recently developed techniques to investigate enamel thickness in 3D and the frequent use of enamel thickness in dietary and phylogenetic interpretations of living and fossil primates, the study presented here aims to produce and make available to other researchers a database of 3D enamel thickness measurements of primate molars (n=182 molars). The 3D enamel thickness measurements reported here generally agree with 2D studies. Hominoids show a broad range of relative enamel thicknesses, and cercopithecoids have relatively thicker enamel than ceboids, which in turn have relatively thicker enamel than strepsirrhine primates, on average. Past studies performed using 2D sections appear to have accurately diagnosed the 3D relative enamel thickness condition in great apes and humans: Gorilla has the relatively thinnest enamel, Pan has relatively thinner enamel than Pongo, and Homo has the relatively thickest enamel. Although the data set presented here has some taxonomic gaps, it may serve as a useful reference for researchers investigating enamel thickness in fossil taxa and studies of primate gnathic biology.

  7. Studies of direct electroinsulating enamels

    International Nuclear Information System (INIS)

    Siwulski, S.; Gruszka, B.; Nocun, M.

    1998-01-01

    The results of studies on the influence of chemical composition of direct electroinsulating enamel on its properties were presented. The influence of alkaline Li 2 O, Na 2 O, K 2 O and adhesion promoting oxides CoO, NiO, CuO, MoO 3 on the frits properties were estimated. The characteristic temperature T g and T m as well as flowability were measured. The dielectric properties of frits and prepared enamels were also measured. Enamel substrates were prepared and tested for application in thick hybrid circuit technology. (author)

  8. Ultrastructure of the surface of dental enamel with molar incisor hypomineralization (MIH) with and without acid etching.

    Science.gov (United States)

    Bozal, Carola B; Kaplan, Andrea; Ortolani, Andrea; Cortese, Silvina G; Biondi, Ana M

    2015-01-01

    The aim of the present work was to analyze the ultrastructure and mineral composition of the surface of the enamel on a molar with MIH, with and without acid etching. A permanent tooth without clinical MIH lesions (control) and a tooth with clinical diagnosis of mild and moderate MIH, with indication for extraction, were processed with and without acid etching (H3PO4 37%, 20") for observation with scanning electron microscope (SEM) ZEISS (Supra 40) and mineral composition analysis with an EDS detector (Oxford Instruments). The control enamel showed normal prismatic surface and etching pattern. The clinically healthy enamel on the tooth with MIH revealed partial loss of prismatic pattern. The mild lesion was porous with occasional cracks. The moderate lesion was more porous, with larger cracks and many scales. The mineral composition of the affected surfaces had lower Ca and P content and higher O and C. On the tooth with MIH, even on normal looking enamel, the demineralization does not correspond to an etching pattern, and exhibits exposure of crystals with rods with rounded ends and less demineralization in the inter-prismatic spaces. Acid etching increased the presence of cracks and deep pores in the adamantine structure of the enamel with lesion. In moderate lesions, the mineral composition had higher content of Ca, P and Cl. Enamel with MIH, even on clinically intact adamantine surfaces, shows severe alterations in the ultrastructure and changes in ionic composition, which affect the acid etching pattern and may interfere with adhesion.

  9. Effects of different amine fluoride concentrations on enamel remineralization.

    Science.gov (United States)

    Naumova, E A; Niemann, N; Aretz, L; Arnold, W H

    2012-09-01

    The aim of this study was to investigate the effects of decreasing fluoride concentrations on repeated demineralizing challenges on human enamel. In 24 teeth, 3mm×3mm windows were prepared on the buccal and lingual sides and treated in a cycling demineralization-remineralization model. Remineralization was achieved with 100, 10 and 0.1 ppm fluoride from anime fluoride. Coronal sections were cut through the artificial lesions, and three sections per tooth were investigated using polarized light microscopy and scanning electron microscopy with quantitative element analysis. The morphology of the lesions was studied, and the extensions of the superficial layer and the body of the lesion were measured. Using element analysis, the Ca, P and F content were determined. The body of the lesion appeared remineralized after application of 100 ppm fluoride, while remineralization of the lesion was less successful after application of 10 and 0.1 ppm fluoride. The thickness of the superficial layer increased with decreasing fluoride concentrations, and also the extension of the body of the lesion increased. Ca and P content increased with increasing fluoride concentrations. The effectiveness of fluoride in enamel remineralization increased with increasing fluoride concentration. A consistently higher level of fluoride in saliva should be a goal in caries prevention. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Enamel resistance to demineralization following Er:YAG laser etching for bonding orthodontic brackets

    Science.gov (United States)

    Ahrari, Farzaneh; Poosti, Maryam; Motahari, Pourya

    2012-01-01

    Background: Several studies have shown that laser-etching of enamel for bonding orthodontic brackets could be an appropriate alternative for acid conditioning, since a potential advantage of laser could or might be caries prevention. This study compared enamel resistance to demineralization following etching with acid phosphoric or Er:YAG laser for bonding orthodontic brackets. Materials and Methods: Fifty sound human premolars were divided into two equal groups. In the first group, enamel was etched with 37% phosphoric acid for 15 seconds. In the second group, Er:YAG laser (wavelength, 2 940 nm; 300 mJ/pulse, 10 pulses per second, 10 seconds) was used for tooth conditioning. The teeth were subjected to 4-day PH-cycling process to induce caries-like lesions. The teeth were then sectioned and the surface area of the lesion was calculated in each microphotographs and expressed in pixel. The total surface of each specimen was 196 608 pixels. Results: Mean lesion areas were 7 171 and 7532 pixels for Laser-etched and Acid-etched groups, respectively. The two sample t-test showed that there was no significant difference in lesion area between the two groups (P = 0.914). Conclusion: Although Er:YAG laser seems promising for etching enamel before bonding orthodontic brackets, it does not reduce enamel demineralization when exposed to acid challenge. PMID:23162591

  11. Clinical evaluation of remineralization potential of casein phosphopeptide amorphous calcium phosphate nanocomplexes for enamel decalcification in orthodontics.

    Science.gov (United States)

    Wang, Jun-xiang; Yan, Yan; Wang, Xiu-jing

    2012-11-01

    Enamel decalcification in orthodontics is a concern for dentists and methods to remineralize these lesions are the focus of intense research. The aim of this study was to evaluate the remineralizing effect of casein phosphopeptide amorphous calcium phosphate (CPP-ACP) nanocomplexes on enamel decalcification in orthodontics. Twenty orthodontic patients with decalcified enamel lesions during fixed orthodontic therapy were recruited to this study as test group and twenty orthodontic patients with the similar condition as control group. GC Tooth Mousse, the main component of which is CPP-ACP, was used by each patient of test group every night after tooth-brushing for six months. For control group, each patient was asked to brush teeth with toothpaste containing 1100 parts per million (ppm) of fluoride twice a day. Standardized intraoral images were taken for all patients and the extent of enamel decalcification was evaluated before and after treatment over this study period. Measurements were statistically compared by t test. After using CPP-ACP for six months, the enamel decalcification index (EDI) of all patients had decreased; the mean EDI before using CPP-ACP was 0.191 ± 0.025 and that after using CPP-ACP was 0.183 ± 0.023, the difference was significant (t = 5.169, P 0.05). CPP-ACP can effectively improve the demineralized enamel lesions during orthodontic treatment, so it has some remineralization potential for enamel decalcification in orthodontics.

  12. Molecular Basis of Human Enamel Defects

    Directory of Open Access Journals (Sweden)

    Chatzopoulos Georgios

    2014-03-01

    Full Text Available During eruption of teeth in the oral cavity, the effect of gene variations and environmental factors can result in morphological and structural changes in teeth. Amelogenesis imperfecta is a failure which is detected on the enamel of the teeth and clinical picture varies by the severity and type of the disease. Classification of the types of amelogenesis imperfecta is determined by histological, genetic, clinical and radiographic criteria. Specifically, there are 4 types of amelogenesis imperfecta (according to Witkop: hypoplastic form, hypo-maturation form, hypo-calcified form, and hypo-maturation/hypoplasia form with taurodontism and 14 subcategories. The diagnosis and classification of amelogenesis imperfecta has traditionally been based on clinical presentation or phenotype and the inheritance pattern. Several genes can be mutated and cause the disease. Millions of genes, possibly more than 10,000 genes produce proteins that regulate synthesis of enamel. Some of the genes and gene products that are likely associated with amelogenesis imperfecta are: amelogenin (AMELX, AMELY genes, ameloblastin (AMBN gene, enamelin (ENAM gene, enamelysin (MMP20 gene, kalikryn 4 (KLK 4 gene, tuftelins (Tuftelin gene, FAM83H (FAM83H gene and WDR72 (WDR72 gene. Particular attention should be given by the dentist in recognition and correlation of phenotypes with genotypes, in order to diagnose quickly and accurately such a possible disease and to prevent or treat it easily and quickly. Modern dentistry should restore these lesions in order to guarantee aesthetics and functionality, usually in collaboration with a group of dentists.

  13. Effects of blue light irradiation on dental enamel remineralization in vitro

    International Nuclear Information System (INIS)

    Kato, Ilka Tiemy

    2009-01-01

    This study aimed to investigate the effects of blue radiation on dental enamel remineralization. In addition, a methodology of analysis was developed to evaluate alterations of enamel mineral content by optical coherence tomography. Artificial lesions were formed in bovine dental enamel slabs by immersing the samples in under saturated acetate buffer (2 mL/mm 2 e 6.25 mL/mm 2 ). The lesions were irradiated with blue LED (l=455±20nm), with radiant power of 110 mW, irradiance of 1.4 W/cm 2 , radiant exposure of 13.8 J/ c m2 and exposure time of 10 s. Remineralization was induced by pH-cycling model during 8 days. Cross-sectional hardness and optical coherence tomography (OCT) were used to assess mineral changes after remineralization. Hardness data showed that non-irradiated enamel lesions presented higher mineral content than irradiated ones and this difference was more evident in lesions formed in higher solution volume. The analysis of OCT signal also demonstrated that the mineral content of non-irradiated group was higher than in irradiated one; however, no significant difference was observed. Furthermore, significant differences in OCT sign were detected between sound and demineralized enamel. Based on the results obtained in the present study it can be concluded that blue radiation caused an inhibition of enamel remineralization. The methodology adopted for OCT analysis allowed the quantification of enamel mineral loss; however, the remineralization process could not be evaluated by this technique. (author)

  14. [In vivo retention of KOH soluble and firmly bound fluoride in demineralized dental enamel].

    Science.gov (United States)

    Hellwig, E; Klimek, J; Albert, G

    1989-03-01

    Cylindrical enamel blocks with initial carious lesions were treated for one hour with Duraphat or Fluor-Protector. After removal of the fluoride varnishes the enamel blocks were kept in the mouths of 3 probands for 5 days. Plaque was allowed to accumulate on half of the enamel cylinders, while the other half was kept clean. Part of the enamel cylinders were retained as fluoridated controls. Compared with Duraphat the application of Fluor-Protector resulted in a significantly higher uptake of KOH soluble and firmly bound fluoride. During the 5 days of the experiment the amount of KOH soluble fluorides decreased in both groups. In the presence of plaque the fluoride loss was higher. The amount of firmly bound fluoride increased both in the plaque covered and in the clean enamel. The durable cariostatic effect of fluoridated varnishes seems to be due to the slow dissolution of Ca F2-like precipitates on the enamel surface and the concomitant fluoride uptake in the underlying demineralized enamel.

  15. Synthetic tooth enamel: SEM characterization of a fluoride hydroxyapatite coating for dentistry applications

    Directory of Open Access Journals (Sweden)

    Marise Oliveira

    2007-06-01

    Full Text Available An alternative to etching enamel for retention of an adhesive is to grow crystals on the enamel surface. The potential advantages of crystal growth include easy procedure and less damage to the enamel. These crystals retain the adhesive or are the actual dental restoration. In this work, a paste of synthetic enamel was used to grow crystals of fluoride hydroxyapatite (F-HA onto the human tooth surface. This technique can be used for several dentistry applications like enamel whitening, strengthening and restoration of early carie lesions. The low cost of reagents and simplicity of the technique along with the biocompatibility of the paste render possible the utilization on the market. The samples were prepared through the application of the paste by the incremental technique. The results obtained by scanning electron microscope (SEM/EDX have indicated the deposition of a homogeneous layer of calcium phosphate that was grown onto the enamel substrate. The average thickness of the deposited film was in the range of 50-100 µm and with a similar density from the natural enamel observed by radiographic images.

  16. Calcium release rates from tooth enamel treated with dentifrices containing whitening agents and abrasives.

    Science.gov (United States)

    Araujo, Danilo Barral; Silva, Luciana Rodrigues; de Araujo, Roberto Paulo Correia

    2010-01-01

    Tooth whitening agents containing hydrogen peroxide and carbamide peroxide are used frequently in esthetic dental procedures. However, lesions on the enamel surface have been attributed to the action of these products. Using conventional procedures for separating and isolating biological structures, powdered enamel was obtained and treated with hydrogen peroxide, carbamide peroxide, and sodium bicarbonate, ingredients typically found in dentifrices. The enamel was exposed to different pH levels, and atomic emission spectrometry was used to determine calcium release rates. As the pH level increased, the rate of calcium release from enamel treated with dentifrices containing whitening agents decreased. Carbamide peroxide produced the lowest amount of decalcification, while sodium bicarbonate produced the highest release rates at all pH levels.

  17. An association of external and internal enamel pearls.

    OpenAIRE

    Mahajan S; Charan C

    2005-01-01

    We report a rare case of an association of external enamel pearl with internal enamel pearl on the root of a molar. To the best of our knowledge, association of external and internal enamel pearls has not been previously reported. We discussed the histogenesis of enamel pearls and proposed that internal enamel pearl formation may be a continuation of formation of external enamel pearl.

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

    Science.gov (United States)

    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. Dental Enamel Defects and Celiac Disease

    Science.gov (United States)

    ... Digestive System & How it Works Zollinger-Ellison Syndrome 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 ...

  20. Properties of hot rolled steels for enamelling

    International Nuclear Information System (INIS)

    Gavrilovski, Dragica; Gavrilovski, Milorad

    2003-01-01

    The results of an investigation of the structure and properties of experimental produced hot rolled steels suitable for enamelling are presented in the paper. Hot rolled steels for enamelling represent a special group of the steels for conventional enamelling. Their quality has to be adapted to the method and conditions of enamelling. Therefore, these steels should meet some specific requirements. In addition to usual investigation of the chemical composition and mechanical properties, microstructure and quality of the steel surface also were investigated. The basic aim was to examine steels capability for enamelling, i. e. steels resistance to the fish scales phenomena, by trial enamelling, as well as quality of the steel - enamel contact surface, to evaluate the binding. Also, the changes of the mechanical properties, especially the yield point, during thermal treatment, as a very specific requirement, were investigated, by simplified method. Good results were obtained confirming the steels capability for enamelling. (Original)

  1. The fracture behaviour of dental enamel

    OpenAIRE

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

    2009-01-01

    Abstract Enamel is the hardest tissue in the human body covering the crowns of teeth. Whereas the underlying dental material dentin is very well characterised in terms of mechanical and fracture properties, available data for enamel are quite limited and are apart from the most recent investigation mainly based on indentation studies. Within the current study, stable crack-growth experiments in bovine enamel have been performed, to measure fracture resistance curves for enamel. Single edge...

  2. The development of enamel tubules during the formation of enamel in the marsupial Monodelphis domestica.

    OpenAIRE

    Sasagawa, I; Ferguson, M W

    1991-01-01

    In Monodelphis domestica, although both processes from odontoblasts and projections from ameloblasts were found in developing enamel, the majority of the contents of enamel tubules were probably processes that originated from odontoblasts. Processes from odontoblasts penetrating into enamel touched part of the ameloblasts in the stage of enamel formation. No specialised cell junctions were seen at the adherence between the two. There were no enamel tubules in the aprismatic and pseudoprismati...

  3. Enamel renal syndrome: A rare case report

    Directory of Open Access Journals (Sweden)

    S V Kala Vani

    2012-01-01

    Full Text Available Enamel renal syndrome is a very rare disorder associating amelogenesis imperfecta with nephrocalcinosis. It is known by various synonyms such as amelogenesis imperfecta nephrocalcinosis syndrome, MacGibbon syndrome, Lubinsky syndrome, and Lubinsky-MacGibbon syndrome. It is characterized by enamel agenesis and medullary nephrocalcinosis. This paper describes enamel renal syndrome in a female patient born in a consanguineous family.

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

    Science.gov (United States)

    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

  5. The in vitro effect of fluoridated milk in a bacterial biofilm--enamel model.

    Science.gov (United States)

    Arnold, Wolfgang H; Forer, Stefan; Heesen, Joerg; Yudovich, Keren; Steinberg, Doron; Gaengler, Peter

    2006-07-01

    The purpose of this study was to investigate the effect of milk and fluoridated milk on bacterially induced caries-like lesions. Extracted impacted human molars were cut in half and covered with a varnish leaving a 4*4 mm window. The samples were coated with biofilm of S. sobrinus and were further divided into three experimental groups of S. sobrinus, S. sobrinus and milk and S. sobrinus and fluoridated milk. As negative controls served teeth incubated in saline. Of twenty tooth halves serial ground sections were cut through the lesions and investigated with polarization light microscopy (PLM) and scanning electron microscopy (SEM) and EDX element analysis. The PLM photographs were used for 3D reconstruction, volumetric assessment and determination of the extension of the lesion zones. Of eight tooth halves the biofilm on the enamel surface was studied with SEM and EDX element analysis. Volumetric assessment showed a statistically significant difference in the volume of the body of the lesion and the translucent zone between the milk group and fluoridated milk group. Quantitative element analysis demonstrated significant differences between sound enamel and the superficial layer in the fluoridated milk group. The biofilm on the enamel surface showed an increased Ca content in the milk group and fluoridated milk group. Milk as a common nutrient seems to play a complex role in in-vitro biofilm--enamel interactions stimulating bacterial demineralization on one hand, and, as effective fluoride carrier, inhibits caries-like demineralization.

  6. Microhardness of demineralized enamel following home bleaching and laser-assisted in office bleaching

    Science.gov (United States)

    Ghanbarzadeh, Majid; Akbari, Majid; Hamzei, Haniye

    2015-01-01

    Background There is little data regarding the effect of tooth whitening on microhardness of white spot lesions. This study was conducted to investigate the effect of home-bleaching and laser-assisted in-office bleaching on microhardness of demineralized enamel. Material and Methods Forty bovine incisors were selected and immersed in a demineralizing solution for 12 weeks to induce white spot lesions. Enamel blocks were prepared and randomly assigned to two groups of 20 each. The first group underwent home bleaching with 15% carbamide peroxide which was applied for 8 hours a day over a period of 15 days. In the second group, in-office bleaching was performed by 40% hydrogen peroxide and powered by irradiation from an 810 nm gallium-aluminum-arsenide (GaAlAs) diode laser (CW, 2W). This process was performed for 3 sessions every seven days, in 15 days. The specimens were stored in Fusayama Meyer artificial saliva during the experiment. Surface microhardness was assessed before and after the bleaching therapies in both groups. Results Microhardness decreased significantly following both home bleaching and laser-assisted in-office bleaching (pTooth whitening through home bleaching or laser-assisted in-office bleaching can result in a significant reduction in microhardness of white spot lesions. Therefore, it is suggested to take protective measures on bleached demineralized enamel. Key words:White spot lesion, bleaching, laser, microhardness, demineralized enamel, home bleaching, in-office bleaching. PMID:26330939

  7. In situ effect of CPP-ACP chewing gum upon erosive enamel loss

    Directory of Open Access Journals (Sweden)

    Catarina Ribeiro Barros de ALENCAR

    Full Text Available Abstract Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP is able to increase salivary calcium and phosphate levels at an acidic pH. Previous studies demonstrated that a CPP-ACP chewing gum was able to enhance the re-hardening of erosion lesions, but could not diminish enamel hardness loss. Therefore, there is no consensus regarding the effectiveness of CPP-ACP on dental erosion. Objective This in situ study investigated the ability of a CPP-ACP chewing gum in preventing erosive enamel loss. Material and Methods: During three experimental crossover phases (one phase per group of seven days each, eight volunteers wore palatal devices with human enamel blocks. The groups were: GI – Sugar free chewing gum with CPP-ACP; GII – Conventional sugar free chewing gum; and GIII – No chewing gum (control. Erosive challenge was extraorally performed by immersion of the enamel blocks in cola drink (5 min, 4x/day. After each challenge, in groups CPP and No CPP, volunteers chewed one unit of the corresponding chewing gum for 30 minutes. Quantitative analysis of enamel loss was performed by profilometry (µm. Data were analyzed by Repeated-Measures ANOVA and Tukey’s test (p0.05. Conclusion The CPP-ACP chewing gum was not able to enhance the anti-erosive effect of conventional chewing gum against enamel loss.

  8. Prevention of enamel demineralization during orthodontic treatment: an in vitro comparative study.

    Science.gov (United States)

    Bichu, Yashodhan M; Kamat, Nandini; Chandra, Pavan Kumar; Kapoor, Aditi; Razmus, Thomas; Aravind, N K S

    2013-01-01

    Enamel demineralization is considered to be the most prevalent and significant iatrogenic effect associated with fixed orthodontic treatment and can seriously jeopardize both tooth longevity and dental esthetics. This in vitro study was undertaken to compare the effectiveness of four different commercially available surface treatment medicaments for the inhibition of enamel demineralization. Seventy-five intact maxillary premolars extracted from patients undergoing orthodontic treatment were divided into five equal groups and were subjected to one of the following protocols: no treatment (control group) or treatment with one of the following four medicaments: fluoride varnish (Fluor Protector [FP]), casein phosphopeptide-amorphous calcium phosphate (GC Tooth Mousse [TM]), calcium sodium phosphosilicate (SHY-NM), and casein phosphopeptide-amorphous calcium phosphate with fluoride (GC Tooth Mousse Plus [TMP]). All the teeth were subjected to ten Cate demineralization solution?for 96 hours and subsequently evaluated under polarized light microscopy to obtain the mean depths of enamel demineralization. One-way analysis of variance and Bonferroni comparison tests were used to obtain statistically significant differences between the five different groups at P < .05. All four surface treatment medicaments provided statistically significant reduction in the depths of enamel demineralization as compared with the control group. FP provided the greatest protection of enamel surface in terms of reduction of lesion depth, followed by TMP, SHY-NM, and TM. The use of these commercially available medicaments could prove to be beneficial for patients undergoing orthodontic treatment and who are at a risk for developing enamel decalcification.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

    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 3 PO 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wei Jie [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Inter-disciplinary Studies, Peking University, Beijing 100871 (China); Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); Wang Jiecheng; Liu Xiaochen [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Inter-disciplinary Studies, Peking University, Beijing 100871 (China); Ma Jian [Hospital of Stomatology, Tongji University, Shanghai 200072 (China); Liu Changsheng [Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science and Technology, Shanghai 200237 (China); Fang Jing, E-mail: biomater2006@yahoo.com.cn [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Inter-disciplinary Studies, Peking University, Beijing 100871 (China); Wei Shicheng, E-mail: nic7505@263.net [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Inter-disciplinary Studies, Peking University, Beijing 100871 (China) and School and Hospital of Stomatology, Peking University, Beijing 100081 (China)

    2011-06-15

    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{sub 3}PO{sub 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.

  11. Concordance between preoperative and postoperative assessments of primary caries lesion depth: results from the Dental PBRN

    DEFF Research Database (Denmark)

    Nascimento, Marcelle M; Bader, James D; Qvist, Vibeke

    2010-01-01

    depths were recorded as being in the outer half (E1) or inner half (E2) of enamel, or in the outer third (D1), middle third (D2) or inner third (D3) of dentin. Most restorations were placed to treat lesions that were preoperatively assessed as extending to the D1 (53%) and D2 (25%) depths....... Of the restored caries lesions, 10% were preoperatively assessed as being limited to E2 depth and 3% to E1 depth. The majority of the restored enamel lesions were located on occlusal surfaces. Preoperative estimates of caries lesion depth were more concordant with postoperative depths when the lesion...... was at an advanced stage: 88% concordance at the D3 depth, compared to 54% concordance at the E1 depth. DPBRN dentists can discriminate caries lesions at different depths, but the accuracy of their depth assessments was higher for dentin than for enamel lesions. In general, DPBRN dentists were more likely...

  12. Effect of gallic acid on the wear behavior of early carious enamel

    Energy Technology Data Exchange (ETDEWEB)

    Gao, S S; Huang, S B; Yu, H Y [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Qian, L M, E-mail: yhyang6812@scu.edu.c [Tribology Research Institute, National Traction Power Laboratory, Southwest Jiaotong University, Chengdu 610031 (China)

    2009-06-15

    The purpose of this research was to investigate the wear behavior of early carious enamel remineralized with gallic acid. Forty natural human premolar specimens with early caries lesions were prepared. A remineralization pH-cycling treatment agent of 4000 ppm gallic acid was used for 12 days to treat the early lesions. The changes in microhardness were monitored. Nanoscratch tests were used to evaluate wear resistance. The experimental data were analyzed by using a t-test. The widths of traces were measured by an AMBIOS XP-2 stylus profilometer. After remineralization, all samples re-hardened significantly. The coefficients of friction became higher, and the widths of scratches were larger than they were before remineralization. Gallic acid significantly improved the early carious enamel's hardness. The wear damage of the samples treated with gallic acid was more severe than that of the control group. There were more obvious cracks and delaminations on the traces of the treated group. Compared with the control group, the enamel remineralized with gallic acid had inferior wear resistance. After remineralization, the dominant damage mechanisms of early carious enamel had changed from plastic deformation and adhesive wear to a combination of brittle cracks and delamination of enamel.

  13. Effect of gallic acid on the wear behavior of early carious enamel

    International Nuclear Information System (INIS)

    Gao, S S; Huang, S B; Yu, H Y; Qian, L M

    2009-01-01

    The purpose of this research was to investigate the wear behavior of early carious enamel remineralized with gallic acid. Forty natural human premolar specimens with early caries lesions were prepared. A remineralization pH-cycling treatment agent of 4000 ppm gallic acid was used for 12 days to treat the early lesions. The changes in microhardness were monitored. Nanoscratch tests were used to evaluate wear resistance. The experimental data were analyzed by using a t-test. The widths of traces were measured by an AMBIOS XP-2 stylus profilometer. After remineralization, all samples re-hardened significantly. The coefficients of friction became higher, and the widths of scratches were larger than they were before remineralization. Gallic acid significantly improved the early carious enamel's hardness. The wear damage of the samples treated with gallic acid was more severe than that of the control group. There were more obvious cracks and delaminations on the traces of the treated group. Compared with the control group, the enamel remineralized with gallic acid had inferior wear resistance. After remineralization, the dominant damage mechanisms of early carious enamel had changed from plastic deformation and adhesive wear to a combination of brittle cracks and delamination of enamel.

  14. Microstructure and nanomechanical properties of enamel remineralized with asparagine-serine-serine peptide

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Hsiu-Ying, E-mail: hychung@mail.fcu.edu.tw; Li, Cheng Che

    2013-03-01

    A highly biocompatible peptide, triplet repeats of asparagine-serine-serine (3NSS) was designed to regulate mineral deposition from aqueous ions in saliva for the reconstruction of enamel lesions. Healthy human enamel was sectioned and acid demineralized to create lesions, then exposed to the 3NSS peptide solution, and finally immersed in artificial saliva for 24 h. The surface morphology and roughness were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. X-ray diffraction (XRD) was used to identify the phases and crystallinity of the deposited minerals observed on the enamel surface. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) was used to quantitatively analyze the mineral variation by calculating the relative integrated-area of characteristic bands. Nanohardness and elastic modulus measured by nanoindentation at various treatment stages were utilized to evaluate the degree of recovery. Biomimetic effects were accessed according to the degree of nanohardness recovery and the amount of hydroxyapatite deposition. The charged segments in the 3NSS peptide greatly attracted aqueous ions from artificial saliva to form hydroxyapatite crystals to fill enamel caries, in particular the interrod areas, resulting in a slight reduction in overall surface roughness. Additionally, the deposited hydroxyapatites were of a small crystalline size in the presence of the 3NSS peptide, which effectively restrained the plastic deformations and thus resulted in greater improvements in nanohardness and elastic modulus. The degree of nanohardness recovery was 5 times greater for remineralized enamel samples treated with the 3NSS peptide compared to samples without peptide treatment. - Highlights: Black-Right-Pointing-Pointer The degree of nanohardness recovery of enamel was 4 times greater with the aid of 3NSS peptide. Black-Right-Pointing-Pointer 3NSS peptide promoted the formation of hydroxyapatites with

  15. Microstructure and nanomechanical properties of enamel remineralized with asparagine–serine–serine peptide

    International Nuclear Information System (INIS)

    Chung, Hsiu-Ying; Li, Cheng Che

    2013-01-01

    A highly biocompatible peptide, triplet repeats of asparagine–serine–serine (3NSS) was designed to regulate mineral deposition from aqueous ions in saliva for the reconstruction of enamel lesions. Healthy human enamel was sectioned and acid demineralized to create lesions, then exposed to the 3NSS peptide solution, and finally immersed in artificial saliva for 24 h. The surface morphology and roughness were examined using scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. X-ray diffraction (XRD) was used to identify the phases and crystallinity of the deposited minerals observed on the enamel surface. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) was used to quantitatively analyze the mineral variation by calculating the relative integrated-area of characteristic bands. Nanohardness and elastic modulus measured by nanoindentation at various treatment stages were utilized to evaluate the degree of recovery. Biomimetic effects were accessed according to the degree of nanohardness recovery and the amount of hydroxyapatite deposition. The charged segments in the 3NSS peptide greatly attracted aqueous ions from artificial saliva to form hydroxyapatite crystals to fill enamel caries, in particular the interrod areas, resulting in a slight reduction in overall surface roughness. Additionally, the deposited hydroxyapatites were of a small crystalline size in the presence of the 3NSS peptide, which effectively restrained the plastic deformations and thus resulted in greater improvements in nanohardness and elastic modulus. The degree of nanohardness recovery was 5 times greater for remineralized enamel samples treated with the 3NSS peptide compared to samples without peptide treatment. - Highlights: ► The degree of nanohardness recovery of enamel was 4 times greater with the aid of 3NSS peptide. ► 3NSS peptide promoted the formation of hydroxyapatites with a smaller crystalline size (14 nm). ► 3NSS

  16. Influence of de/remineralization of enamel on the tensile bond strength of etch-and-rinse and self-etching adhesives.

    Science.gov (United States)

    Farias de Lacerda, Ana Julia; Ferreira Zanatta, Rayssa; Crispim, Bruna; Borges, Alessandra Bühler; Gomes Torres, Carlos Rocha; Tay, Franklin R; Pucci, Cesar Rogério

    2016-10-01

    To evaluate the bonding behavior of resin composite and different adhesives applied to demineralized or remineralized enamel. Bovine tooth crowns were polished to prepare a 5 mm2 enamel bonding area, and divided into five groups (n= 48) according to the surface treatment: CONT (sound enamel control), DEM (demineralized with acid to create white spot lesions), REMS (DEM remineralized with artificial saliva), REMF (DEM remineralized with sodium fluoride) and INF (DEM infiltrated with Icon resin infiltrant). The surface-treated teeth were divided into two subgroups (n= 24) according to adhesive type: ER (etch-and-rinse; Single Bond Universal) and SE (self-etching; Clearfill S3 Bond), and further subdivided into two categories (n= 12) according to aging process: Thermo (thermocycling) and NA (no aging). Composite blocks were made over bonded enamel and sectioned for microtensile bond strength (MTBS) testing. Data were analyzed with three-way ANOVA and post-hoc Tukey's test (α= 0.05). Significant differences were observed for enamel surface treatment (Padhesive type (PUniversal had higher MTBS than Clearfil S3 Bond; thermo-aging resulted in lower MTBS irrespective of adhesive type and surface treatment condition. The predominant failure mode was mixed for all groups. Enamel surface infiltrated with Icon does not interfere with adhesive resin bonding procedures. Treatment of enamel surface containing white spot lesions or cavities with cavosurface margins in partially-demineralized enamel can benefit from infiltration with a low viscosity resin infiltrant prior to adhesive bonding of resin composites.

  17. In Vivo Remineralization of Artificial Carious Lesions using Calcifying Solution and Fluoride Solution

    Directory of Open Access Journals (Sweden)

    Els Sunarsih Budipramana

    2015-10-01

    Full Text Available The remineralization potential of fluoride and calcifying solution was studiedas in situ model. Matched enamel discs of artifically demineralized human enamel were attached to an acrylic mandibular removable appliance of 6 adult volunteers who rinsed their mouth with a solution containing either 50 ppm F-, 200 ppm F- in amine fluoride, calcifying solution (formula BR21 or placebo as a control. The volunteers were asked to rinse 3 times a day for 3 minutes with 15 ml of the solution for 6 days (18 times. On the 7th day enamel discs were taken out from the partial denture. Three kinds of measurements were done: enamel permeability testing, depth lesion testing and fluoride retention testing. New demineralized enamel discs were attached to the partial dentures and the volunteers were asked to start rinsing with other solutions using the same protocols. The purpose of this study was to answer the question why the calcifying solutions were no more used as a remineralizing solution. The data ws analyzed using SPSS/PC for two factors Anova and one way Anova for enamel permeability and Kruskal Wallis for studying enamel depth lesion and fluoride retention. There was no significant difference after rinsing with calcifying solution and placebo in enamel permeability, depth lesions, and fluoride retention when compared to fluoride solution. To get a better result in remineralizing carious teeth fluoride contents in solution must be higher than 50 ppm F-.

  18. Effect of ozone to remineralize initial enamel caries: in situ study.

    Science.gov (United States)

    Samuel, S R; Dorai, S; Khatri, S G; Patil, S T

    2016-06-01

    Effect of ozonated water in remineralizing artificially created initial enamel caries was investigated using laser fluorescence and polarized light microscopy in an in situ study. Teeth specimens (buccal sections) were immersed in 5-ml solution of 2 mM CaCl2, 2 mM NaH2P04, and 50 mM CH3COOH at pH of 4.55 for 5 h in an incubator at 37° to create subsurface demineralization. After which, they were randomly allocated into one of the following remineralization regimens: ozone (ozonated water 0.1 mg/l and 10 % nano-hydroxyapatite paste, Aclaim(TM)), without ozone (only 10 % nano-hydroxyapatite paste, Aclaim(TM)), and control (subjects' saliva alone). Specimens were embedded in acrylic retainers worn by orthodontic patients throughout the 21-day study duration and constantly exposed to their saliva. Laser fluorescence was recorded for all the specimens at baseline, after demineralization, and remineralization using DIAGNOdent, and the results were validated using polarized microscopic examination. The results were analyzed using repeated measures, one-way ANOVA with post hoc multiple comparisons. Reduced DIAGNOdent scores and greater depth of remineralization following application of ozonated water and nano-hydroxyapatite were found compared to those of the without ozone and control groups (P nano-hydroxyapatite compared to nano-hydroxyapatite alone and saliva. Ozone water can be used to remineralize incipient carious lesions, and it enhances the remineralizing potential of nano-hydroxyapatite thereby preventing the tooth from entering into the repetitive restorative cycle.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Komatsu, H. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan)]. E-mail: kom@den.hokudai.ac.jp; Yamamoto, H. [Graduate School of Dentistry, Osaka University, 1-8 Yamada-Oka, Suita 565-0871 (Japan); Nomachi, M. [Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043 (Japan); Yasuda, K. [Wakasa wan Energy Research Center, 64-52-1 Hase, Tsuruga 914-0192 (Japan); Matsuda, Y. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Murata, Y. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Kijimura, T. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Sano, H. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Sakai, T. [Takasaki Advanced Radiation Research Institute, JAEA, 1233 Watanuki-machi, Takasaki 370-1292 (Japan); Kamiya, T. [Takasaki Advanced Radiation Research Institute, JAEA, 1233 Watanuki-machi, Takasaki 370-1292 (Japan)

    2007-07-15

    duration of pH cycling, although 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.

  1. Biofilm three-dimensional architecture influences in situ pH distribution pattern on the human enamel surface.

    Science.gov (United States)

    Xiao, Jin; Hara, Anderson T; Kim, Dongyeop; Zero, Domenick T; Koo, Hyun; Hwang, Geelsu

    2017-06-01

    To investigate how the biofilm three-dimensional (3D) architecture influences in situ pH distribution patterns on the enamel surface. Biofilms were formed on human tooth enamel in the presence of 1% sucrose or 0.5% glucose plus 0.5% fructose. At specific time points, biofilms were exposed to a neutral pH buffer to mimic the buffering of saliva and subsequently pulsed with 1% glucose to induce re-acidification. Simultaneous 3D pH mapping and architecture of intact biofilms was performed using two-photon confocal microscopy. The enamel surface and mineral content characteristics were examined successively via optical profilometry and microradiography analyses. Sucrose-mediated biofilm formation created spatial heterogeneities manifested by complex networks of bacterial clusters (microcolonies). Acidic regions (pHinterior of microcolonies, which impedes rapid neutralization (taking more than 120 min for neutralization). Glucose exposure rapidly re-created the acidic niches, indicating formation of diffusion barriers associated with microcolonies structure. Enamel demineralization (white spots), rougher surface, deeper lesion and more mineral loss appeared to be associated with the localization of these bacterial clusters at the biofilm-enamel interface. Similar 3D architecture was observed in plaque-biofilms formed in vivo in the presence of sucrose. The formation of complex 3D architectures creates spatially heterogeneous acidic microenvironments in close proximity of enamel surface, which might correlate with the localized pattern of the onset of carious lesions (white spot like) on teeth.

  2. Electrical Subsurface Grounding Analysis

    International Nuclear Information System (INIS)

    J.M. Calle

    2000-01-01

    The purpose and objective of this analysis is to determine the present grounding requirements of the Exploratory Studies Facility (ESF) subsurface electrical system and to verify that the actual grounding system and devices satisfy the requirements

  3. Deep subsurface microbial processes

    Science.gov (United States)

    Lovley, D.R.; Chapelle, F.H.

    1995-01-01

    Information on the microbiology of the deep subsurface is necessary in order to understand the factors controlling the rate and extent of the microbially catalyzed redox reactions that influence the geophysical properties of these environments. Furthermore, there is an increasing threat that deep aquifers, an important drinking water resource, may be contaminated by man's activities, and there is a need to predict the extent to which microbial activity may remediate such contamination. Metabolically active microorganisms can be recovered from a diversity of deep subsurface environments. The available evidence suggests that these microorganisms are responsible for catalyzing the oxidation of organic matter coupled to a variety of electron acceptors just as microorganisms do in surface sediments, but at much slower rates. The technical difficulties in aseptically sampling deep subsurface sediments and the fact that microbial processes in laboratory incubations of deep subsurface material often do not mimic in situ processes frequently necessitate that microbial activity in the deep subsurface be inferred through nonmicrobiological analyses of ground water. These approaches include measurements of dissolved H2, which can predict the predominant microbially catalyzed redox reactions in aquifers, as well as geochemical and groundwater flow modeling, which can be used to estimate the rates of microbial processes. Microorganisms recovered from the deep subsurface have the potential to affect the fate of toxic organics and inorganic contaminants in groundwater. Microbial activity also greatly influences 1 the chemistry of many pristine groundwaters and contributes to such phenomena as porosity development in carbonate aquifers, accumulation of undesirably high concentrations of dissolved iron, and production of methane and hydrogen sulfide. Although the last decade has seen a dramatic increase in interest in deep subsurface microbiology, in comparison with the study of

  4. Site Recommendation Subsurface Layout

    International Nuclear Information System (INIS)

    C.L. Linden

    2000-01-01

    The purpose of this analysis is to develop a Subsurface Facility layout that is capable of accommodating the statutory capacity of 70,000 metric tons of uranium (MTU), as well as an option to expand the inventory capacity, if authorized, to 97,000 MTU. The layout configuration also requires a degree of flexibility to accommodate potential changes in site conditions or program requirements. The objective of this analysis is to provide a conceptual design of the Subsurface Facility sufficient to support the development of the Subsurface Facility System Description Document (CRWMS M andO 2000e) and the ''Emplacement Drift System Description Document'' (CRWMS M andO 2000i). As well, this analysis provides input to the Site Recommendation Consideration Report. The scope of this analysis includes: (1) Evaluation of the existing facilities and their integration into the Subsurface Facility design. (2) Identification and incorporation of factors influencing Subsurface Facility design, such as geological constraints, thermal loading, constructibility, subsurface ventilation, drainage control, radiological considerations, and the Test and Evaluation Facilities. (3) Development of a layout showing an available area in the primary area sufficient to support both the waste inventories and individual layouts showing the emplacement area required for 70,000 MTU and, if authorized, 97,000 MTU

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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. (papers)

  7. Effect of acidity upon attrition-corrosion of human dental enamel.

    Science.gov (United States)

    Wu, Yun-Qi; Arsecularatne, Joseph A; Hoffman, Mark

    2015-04-01

    Attrition-corrosion is a synthesized human enamel wear process combined mechanical effects (attrition) with corrosion. With the rising consumption of acidic food and beverages, attrition-corrosion is becoming increasingly common. Yet, research is limited and the underlying mechanism remains unclear. In this study, in vitro wear loss of human enamel was investigated and the attrition-corrosion process and wear mechanism were elucidated by the analysis of the wear scar and its subsurface using focused ion beam (FIB) sectioning and scanning electron microscopy (SEM). Human enamel flat-surface samples were prepared with enamel cusps as the wear antagonists. Reciprocating wear testing was undertaken under load of 5N at the speed of 66 cycle/min for 2250 cycles with lubricants including citric acid (at pH 3.2 and 5.5), acetic acid (at pH 3.2 and 5.5) and distilled water. All lubricants were used at 37°C. Similar human enamel flat-surface samples were also exposed to the same solutions as a control group. The substance loss of enamel during wear can be linked to the corrosion potential of a lubricant used. Using a lubricant with very low corrosion potential (such as distilled water), the wear mechanism was dominated by delamination with high wear loss. Conversely, the wear mechanism changed to shaving of the softened layer with less material loss in an environment with medium corrosion potential such as citric acid at pH 3.2 and 5.5 and acetic acid at pH 5.5. However, a highly corrosive environment (e.g., acetic acid at pH 3.2) caused the greatest loss of substance during wear. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Dental enamel cells express functional SOCE channels.

    Science.gov (United States)

    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

    2015-10-30

    Dental enamel formation requires large quantities of Ca(2+) yet the mechanisms mediating Ca(2+) dynamics in enamel cells are unclear. Store-operated Ca(2+) entry (SOCE) channels are important Ca(2+) influx mechanisms in many cells. SOCE involves release of Ca(2+) from intracellular pools followed by Ca(2+) entry. The best-characterized SOCE channels are the Ca(2+) release-activated Ca(2+) (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 Ca(2+) 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 Ca(2+) release mechanism. Passive depletion of ER Ca(2+) stores with thapsigargin resulted in a significant raise in [Ca(2+)]i consistent with SOCE. In cells pre-treated with the CRAC channel blocker Synta-66 Ca(2+) entry was significantly inhibited. These data demonstrate that enamel cells have SOCE mediated by CRAC channels and implicate them as a mechanism for Ca(2+) uptake in enamel formation.

  9. Subsurface Contamination Control

    Energy Technology Data Exchange (ETDEWEB)

    Y. Yuan

    2001-12-12

    There are two objectives of this report, ''Subsurface Contamination Control''. The first is to provide a technical basis for recommending limiting radioactive contamination levels (LRCL) on the external surfaces of waste packages (WP) for acceptance into the subsurface repository. The second is to provide an evaluation of the magnitude of potential releases from a defective WP and the detectability of the released contents. The technical basis for deriving LRCL has been established in ''Retrieval Equipment and Strategy for Wp on Pallet'' (CRWMS M and O 2000g, 6.3.1). This report updates the derivation by incorporating the latest design information of the subsurface repository for site recommendation. The derived LRCL on the external surface of WPs, therefore, supercede that described in CRWMS M and O 2000g. The derived LRCL represent the average concentrations of contamination on the external surfaces of each WP that must not be exceeded before the WP is to be transported to the subsurface facility for emplacement. The evaluation of potential releases is necessary to control the potential contamination of the subsurface repository and to detect prematurely failed WPs. The detection of failed WPs is required in order to provide reasonable assurance that the integrity of each WP is intact prior to MGR closure. An emplaced WP may become breached due to manufacturing defects or improper weld combined with failure to detect the defect, by corrosion, or by mechanical penetration due to accidents or rockfall conditions. The breached WP may release its gaseous and volatile radionuclide content to the subsurface environment and result in contaminating the subsurface facility. The scope of this analysis is limited to radioactive contaminants resulting from breached WPs during the preclosure period of the subsurface repository. This report: (1) documents a method for deriving LRCL on the external surfaces of WP for acceptance into the

  10. Femtosecond laser ablation of enamel

    Science.gov (United States)

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

    2016-06-01

    The surface topographical, compositional, and structural modifications induced in human enamel by femtosecond laser ablation is studied. The laser treatments were performed using a Yb:KYW chirped-pulse-regenerative amplification laser system (560 fs and 1030 nm) and fluences up to 14 J/cm2. The ablation surfaces were studied by scanning electron microscopy, grazing incidence x-ray diffraction, and micro-Raman spectroscopy. Regardless of the fluence, the ablation surfaces were covered by a layer of resolidified material, indicating that ablation is accompanied by melting of hydroxyapatite. This layer presented pores and exploded gas bubbles, created by the release of gaseous decomposition products of hydroxyapatite (CO2 and H2O) within the liquid phase. In the specimen treated with 1-kHz repetition frequency and 14 J/cm2, thickness of the resolidified material is in the range of 300 to 900 nm. The micro-Raman analysis revealed that the resolidified material contains amorphous calcium phosphate, while grazing incidence x-ray diffraction analysis allowed detecting traces of a calcium phosphate other than hydroxyapatite, probably β-tricalcium phosphate Ca3), at the surface of this specimen. The present results show that the ablation of enamel involves melting of enamel's hydroxyapatite, but the thickness of the altered layer is very small and thermal damage of the remaining material is negligible.

  11. Dental enamel defects in adult coeliac disease: prevalence and correlation with symptoms and age at diagnosis.

    Science.gov (United States)

    Trotta, Lucia; Biagi, Federico; Bianchi, Paola I; Marchese, Alessandra; Vattiato, Claudia; Balduzzi, Davide; Collesano, Vittorio; Corazza, Gino R

    2013-12-01

    Coeliac disease is a condition characterized by a wide spectrum of clinical manifestations. Any organ can be affected and, among others, dental enamel defects have been described. Our aims were to study the prevalence of dental enamel defects in adults with coeliac disease and to investigate a correlation between the grade of teeth lesion and clinical parameters present at the time of diagnosis of coeliac disease. A dental examination was performed in 54 coeliac disease patients (41 F, mean age 37 ± 13 years, mean age at diagnosis 31 ± 14 years). Symptoms leading to diagnosis were diarrhoea/weight loss (32 pts.), anaemia (19 pts.), familiarity (3 pts.); none of the patients was diagnosed because of enamel defects. At the time of evaluation, they were all on a gluten-free diet. Enamel defects were classified from grade 0 to 4 according to its severity. Enamel defects were observed in 46/54 patients (85.2%): grade 1 defects were seen in 18 patients (33.3%) grade 2 in 16 (29.6%), grade 3 in 8 (14.8%), and grade 4 in 4 (7.4%). We also observed that grades 3 and 4 were more frequent in patients diagnosed with classical rather than non-classical coeliac disease (10/32 vs. 2/20). However, this was not statistically significant. This study confirms that enamel defects are common in adult coeliac disease. Observation of enamel defects is an opportunity to diagnose coeliac disease. Copyright © 2013 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  12. Confocal examination of subsurface cracking in ceramic materials.

    Science.gov (United States)

    Etman, Maged K

    2009-10-01

    The original ceramic surface finish and its microstructure may have an effect on crack propagation. The purpose of this study was to investigate the relation between crack propagation and ceramic microstructure following cyclic fatigue loading, and to qualitatively evaluate and quantitatively measure the surface and subsurface crack depths of three types of ceramic restorations with different microstructures using a Confocal Laser Scanning Microscope (CLSM) and Scanning Electron Microscope (SEM). Twenty (8 x 4 x 2 mm(3)) blocks of AllCeram (AC), experimental ceramic (EC, IPS e.max Press), and Sensation SL (SSL) were prepared, ten glazed and ten polished of each material. Sixty antagonist enamel specimens were made from the labial surfaces of permanent incisors. The ceramic abraders were attached to a wear machine, so that each enamel specimen presented at 45 degrees to the vertical movement of the abraders, and immersed in artificial saliva. Wear was induced for 80K cycles at 60 cycles/min with a load of 40 N and 2-mm horizontal deflection. The specimens were examined for cracks at baseline, 5K, 10K, 20K, 40K, and 80K cycles. Twenty- to 30-microm deep subsurface cracking appeared in SSL, with 8 to 10 microm in AC, and 7 microm close to the margin of the wear facets in glazed EC after 5K cycles. The EC showed no cracks with increasing wear cycles. Seventy-microm deep subsurface cracks were detected in SSL and 45 microm in AC after 80K cycles. Statistically, there was significant difference among the three materials (p 0.05) in crack depth within the same ceramic material with different surface finishes. The ceramic materials with different microstructures showed different patterns of subsurface cracking.

  13. Enamel Regeneration - Current Progress and Challenges

    Science.gov (United States)

    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

  14. The Serpentinite Subsurface Microbiome

    Science.gov (United States)

    Schrenk, M. O.; Nelson, B. Y.; Brazelton, W. J.

    2011-12-01

    Microbial habitats hosted in ultramafic rocks constitute substantial, globally-distributed portions of the subsurface biosphere, occurring both on the continents and beneath the seafloor. The aqueous alteration of ultramafics, in a process known as serpentinization, creates energy rich, high pH conditions, with low concentrations of inorganic carbon which place fundamental constraints upon microbial metabolism and physiology. Despite their importance, very few studies have attempted to directly access and quantify microbial activities and distributions in the serpentinite subsurface microbiome. We have initiated microbiological studies of subsurface seeps and rocks at three separate continental sites of serpentinization in Newfoundland, Italy, and California and compared these results to previous analyses of the Lost City field, near the Mid-Atlantic Ridge. In all cases, microbial cell densities in seep fluids are extremely low, ranging from approximately 100,000 to less than 1,000 cells per milliliter. Culture-independent analyses of 16S rRNA genes revealed low-diversity microbial communities related to Gram-positive Firmicutes and hydrogen-oxidizing bacteria. Interestingly, unlike Lost City, there has been little evidence for significant archaeal populations in the continental subsurface to date. Culturing studies at the sites yielded numerous alkaliphilic isolates on nutrient-rich agar and putative iron-reducing bacteria in anaerobic incubations, many of which are related to known alkaliphilic and subsurface isolates. Finally, metagenomic data reinforce the culturing results, indicating the presence of genes associated with organotrophy, hydrogen oxidation, and iron reduction in seep fluid samples. Our data provide insight into the lifestyles of serpentinite subsurface microbial populations and targets for future quantitative exploration using both biochemical and geochemical approaches.

  15. Accelerated enamel mineralization in Dspp mutant mice

    Science.gov (United States)

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

    2016-01-01

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

  16. In vitro wear of four ceramic materials and human enamel on enamel antagonist.

    Science.gov (United States)

    Nakashima, Jun; Taira, Yohsuke; Sawase, Takashi

    2016-06-01

    The purpose of the present study was to evaluate the wear of four different ceramics and human enamel. The ceramics used were lithium disilicate glass (e.max Press), leucite-reinforced glass (GN-Ceram), yttria-stabilized zirconia (Aadva Zr), and feldspathic porcelain (Porcelain AAA). Hemispherical styli were fabricated with these ceramics and with tooth enamel. Flattened enamel was used for antagonistic specimens. After 100,000 wear cycles of a two-body wear test, the height and volume losses of the styli and enamel antagonists were determined. The mean and standard deviation for eight specimens were calculated and statistically analyzed using a non-parametric (Steel-Dwass) test (α = 0.05). GN-Ceram exhibited greater stylus height and volume losses than did Porcelain AAA. E.max Press, Porcelain AAA, and enamel styli showed no significant differences, and Aadva Zr exhibited the smallest stylus height and volume losses. The wear of the enamel antagonist was not significantly different among GN-Ceram, e.max Press, Porcelain AAA, and enamel styli. Aadva Zr resulted in significantly lower wear values of the enamel antagonist than did GN-Ceram, Porcelain AAA, and enamel styli. In conclusion, leucite-reinforced glass, lithium disilicate glass, and feldspathic porcelain showed wear values closer to those for human enamel than did yttria-stabilized zirconia. © 2016 Eur J Oral Sci.

  17. SUBSURFACE EMPLACEMENT TRANSPORTATION SYSTEM

    International Nuclear Information System (INIS)

    Wilson, T.; Novotny, R.

    1999-01-01

    The objective of this analysis is to identify issues and criteria that apply to the design of the Subsurface Emplacement Transportation System (SET). The SET consists of the track used by the waste package handling equipment, the conductors and related equipment used to supply electrical power to that equipment, and the instrumentation and controls used to monitor and operate those track and power supply systems. Major considerations of this analysis include: (1) Operational life of the SET; (2) Geometric constraints on the track layout; (3) Operating loads on the track; (4) Environmentally induced loads on the track; (5) Power supply (electrification) requirements; and (6) Instrumentation and control requirements. This analysis will provide the basis for development of the system description document (SDD) for the SET. This analysis also defines the interfaces that need to be considered in the design of the SET. These interfaces include, but are not limited to, the following: (1) Waste handling building; (2) Monitored Geologic Repository (MGR) surface site layout; (3) Waste Emplacement System (WES); (4) Waste Retrieval System (WRS); (5) Ground Control System (GCS); (6) Ex-Container System (XCS); (7) Subsurface Electrical Distribution System (SED); (8) MGR Operations Monitoring and Control System (OMC); (9) Subsurface Facility System (SFS); (10) Subsurface Fire Protection System (SFR); (11) Performance Confirmation Emplacement Drift Monitoring System (PCM); and (12) Backfill Emplacement System (BES)

  18. Dentifrice fluoride and abrasivity interplay on artificial caries lesions.

    Science.gov (United States)

    Nassar, Hani M; Lippert, Frank; Eckert, George J; Hara, Anderson T

    2014-01-01

    Incipient caries lesions on smooth surfaces may be subjected to toothbrushing, potentially leading to remineralization and/or abrasive wear. The interplay of dentifrice abrasivity and fluoride on this process is largely unknown and was investigated on three artificially created lesions with different mineral content/distribution. 120 bovine enamel specimens were randomly allocated to 12 groups (n = 10), resulting from the association of (1) lesion type [methylcellulose acid gel (MeC); carboxymethylcellulose solution (CMC); hydroxyethylcellulose gel (HEC)], (2) slurry abrasive level [low (REA 4/ RDA 69); high (REA 7/RDA 208)], and (3) fluoride concentration [0/275 ppm (14.5 mM) F as NaF]. After lesion creation, specimens were brushed in an automated brushing machine with the test slurries (50 strokes 2×/day). Specimens were kept in artificial saliva in between brushings and overnight. Enamel surface loss (SL) was determined by optical profilometry after lesion creation, 1, 3 and 5 days. Two enamel sections (from baseline and post-brushing areas) were obtained and analyzed microradiographically. Data were analyzed by analysis of variance and Tukey's tests (α = 5%). Brushing with high-abrasive slurry caused more SL than brushing with low-abrasive slurry. For MeC and CMC lesions, fluoride had a protective effect on SL from day 3 on. Furthermore, for MeC and CMC, there was a significant mineral gain in the remaining lesions except when brushed with high-abrasive slurries and 0 ppm F. For HEC, a significant mineral gain took place when low-abrasive slurry was used with fluoride. The tested lesions responded differently to the toothbrushing procedures. Both slurry fluoride content and abrasivity directly impacted SL and mineral gain of enamel caries lesions.

  19. ON THE R-CURVE BEHAVIOR OF HUMAN TOOTH ENAMEL

    OpenAIRE

    Bajaj, Devendra; Arola, Dwayne

    2009-01-01

    In this study the crack growth resistance behavior and fracture toughness of human tooth enamel were quantified using incremental crack growth measures and conventional fracture mechanics. Results showed that enamel undergoes an increase in crack growth resistance (i.e. rising R-curve) with crack extension from the outer to the inner enamel, and that the rise in toughness is function of distance from the Dentin Enamel Junction (DEJ). The outer enamel exhibited the lowest apparent toughness (0...

  20. Effect of CO2 Laser and Fluoride Varnish Application on Microhardness of Enamel Surface Around Orthodontic Brackets.

    Science.gov (United States)

    Mahmoudzadeh, Majid; Rezaei-Soufi, Loghman; Farhadian, Nasrin; Jamalian, Seyed Farzad; Akbarzadeh, Mahdi; Momeni, Mohammadali; Basamtabar, Masome

    2018-01-01

    Introduction: Orthodontic treatment has many advantages such as esthetic improvement and self-esteem enhancement; yet it has some disadvantages such as increasing the risk of formation of white spot lesions, because it makes oral hygiene more difficult. It is rational to implement procedures to prevent these lesions. The present study was aimed to assess the effect of CO 2 laser and fluoride varnish on the surface of the enamel surface microhardness around the orthodontic braces. Methods: Eighty extracted premolar teeth were selected, scaled, polished with nonfluoridated pumic and metal brackets were bonded to them. Then, they were randomly allocated to 5 groups: control (neither fluoride nor laser is used on enamel surfaces), fluoride (4 minutes fluoride varnish treatment of the enamel surfaces), CO 2 laser (10.6 µm CO 2 laser irradiation of the teeth), laserfluoride (fluoride application after laser irradiation) and fluoride-laser (fluoride was applied and then teeth were irradiated with laser). After surface treatment around brackets on enamel, the samples were stored in 0.1% thymol for less than 5 days and then they were exposed to a 10-day microbiological caries model. Microhardness values of enamel were evaluated with Vickers test. One sample of each group (5 teeth from 80 samples) was prepared for SEM (scanning electron microscopy) and the data from 75 remaining teeth were analyzed with analysis of variance (ANOVA) and chi-square tests (α =0.05). Results: Microhardness mean values from high to low were as follow: fluoride-laser, laser-fluoride, laser, fluoride and control. Microhardness in fluoride-laser group was significantly higher compared with that of the control group. Distribution adhesive remnant index (ARI) scores were significantly different between groups and most of bond failures occurred at the enamel-adhesive interface in groups 2 to 5 and at the adhesive-bracket interface in the control group. Conclusion: Combination of fluoride varnish and

  1. Regulation of Dental Enamel Shape and Hardness

    Science.gov (United States)

    Simmer, J.P.; Papagerakis, P.; Smith, C.E.; Fisher, D.C.; Rountrey, A.N.; Zheng, L.; Hu, J.C.-C.

    2010-01-01

    Epithelial-mesenchymal interactions guide tooth development through its early stages and establish the morphology of the dentin surface upon which enamel will be deposited. Starting with the onset of amelogenesis beneath the future cusp tips, the shape of the enamel layer covering the crown is determined by five growth parameters: the (1) appositional growth rate, (2) duration of appositional growth (at the cusp tip), (3) ameloblast extension rate, (4) duration of ameloblast extension, and (5) spreading rate of appositional termination. Appositional growth occurs at a mineralization front along the ameloblast distal membrane in which amorphous calcium phosphate (ACP) ribbons form and lengthen. The ACP ribbons convert into hydroxyapatite crystallites as the ribbons elongate. Appositional growth involves a secretory cycle that is reflected in a series of incremental lines. A potentially important function of enamel proteins is to ensure alignment of successive mineral increments on the tips of enamel ribbons deposited in the previous cycle, causing the crystallites to lengthen with each cycle. Enamel hardens in a maturation process that involves mineral deposition onto the sides of existing crystallites until they interlock with adjacent crystallites. Neutralization of acidity generated by hydroxyapatite formation is a key part of the mechanism. Here we review the growth parameters that determine the shape of the enamel crown as well as the mechanisms of enamel appositional growth and maturation. PMID:20675598

  2. Development, characterization and comparison of two strontium doped nano hydroxyapatite molecules for enamel repair/regeneration.

    Science.gov (United States)

    Krishnan, Vinod; Bhatia, Ankit; Varma, Harikrishna

    2016-05-01

    Enamel damage resulting or arising from/associated with orthodontic treatment such as white spot lesions and surface deterioration after debonding brackets along with incipient carious lesions are considered problems not amenable for routine restorations due to its invasive nature. The present study was aimed at synthesizing and characterizing nHAp and 25 and 50 mol% strontium nHAp as a surface application modality for dental enamel remineralization/repair. 25 and 50 mol% Sr nHAp was synthesized and characterized in comparison with custom made pure nHAp initially with the help of transmission and scanning electron microscopy as well as toxicological assessment. Further, comparative evaluation of these novel synthesized strontium substituted particles was assessed for its efficacy in repairing damaged enamel with the help of atomic force microscopy, scanning electron microscopy and micro indentation testing. There is increase in crystallinity and reduced particle size favoring dissolution and re-precipitation through small incipient carious lesions and soft white spot areas with 25% Sr-nHAp. Sr doped specimens showed more cell viability in comparison with pure nHAP make it less cytotoxic and hence a biologically friendly material which can be safely applied in patient's mouth. AFM images obtained from 25% and 50% Sr nHAp treated specimens clearly indicated increased roughness in surface topography and performed well with micro indentation test. The novel synthesized Sr doped nHAp forms an improved treatment modality to tackle the long standing quest for solving the problem of enamel loss with incipient carious lesions and WSL from orthodontic procedures. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. Weaker dental enamel explains dental decay.

    Science.gov (United States)

    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.

  4. Analysis of enamel microhardness at various hard tissue states and depth of the microfissures

    Directory of Open Access Journals (Sweden)

    S. P. Yarova

    2013-08-01

    Full Text Available In clinical practice are often diagnosed precervical lesions: wedge-shaped defects and cracks. Long phases of the confrontation of the body as a damaging influence in the formation of thicker tissue sections of higher salinity, density and sustainability occur prior to the integrity of the enamel. Micro-hardness is one of the important characteristics of the micro-mechanical strength of the tooth-related physical and chemical changes that occur in the enamel as a result of external and internal influences. The purpose of the study was to identify possible differences in the micro-hardness of enamel, depending on the depth of fissures and pathology of hard tissues of the teeth. We investigated the longitudinal sections of 27 teeth (18 - intact, 5 - with wedge-shaped defect, 4 - with cervical caries of both jaws removed for clinical indications in patients aged 25-54 years, who were diagnosed three types of fractures (SB Ivanov, 1984. Hardness was determined in the outer, middle, inner layers of enamel in three topographical locations: in the cusp tip (cutting edge of the tooth equator and neck as in previously described technique (S. Remizov, 1965. The obtained results showed decrease in strength with micro-cracks enamel, compared with apparently intact ones, on the average 10% more in the incisal areas (tuber, less - in the equatorial zone. In intact teeth with micro-cracks and having a wedge-shaped defect the indices differed significantly depending on the depth of the defects of the cutting edge (tuber and the equator: they were the smallest in the deep type III micro-cracks (p <0.05. The opposite picture was observed in samples with cervical caries. Thus, the statistically significant difference in terms of the micro-hardness of the enamel, depending on the depth of defects has been identified only in the area of cutting edge (tuber: in samples with deep micro-cracks of enamel type III they were the highest (P = 0.017. The greatest values of

  5. MMP20 Promotes a Smooth Enamel Surface, a Strong DEJ, and a Decussating Enamel Rod Pattern

    Science.gov (United States)

    Bartlett, John D.; Skobe, Ziedonis; Nanci, Antonio; Smith, Charles E.

    2012-01-01

    Mutations of the Matrix metalloproteinase-20 (MMP20, enamelysin) gene cause autosomal recessive amelogenesis imperfecta and Mmp20 ablated mice also have malformed dental enamel. Here we show that Mmp20 null mouse secretory stage ameloblasts maintained a columnar shape and were present as a single layer of cells. However, the null maturation stage ameloblasts covered extraneous nodules of ectopic calcified material formed at the enamel surface. Remarkably, nodule formation occurs in null mouse enamel when MMP20 is normally no longer expressed. The malformed enamel in Mmp20 null teeth was loosely attached to the dentin and the entire enamel layer tended to separate from the dentin indicative of a faulty DEJ. The enamel rod pattern was also altered in Mmp20 null mice. Each enamel rod is formed by a single ameloblast and is a mineralized record of the migration path of the ameloblast that formed it. The Mmp20 null mouse enamel rods were grossly malformed or were absent indicating that the ameloblasts do not migrate properly when backing away from the DEJ. Thus, MMP20 is required for ameloblast cell movement necessary to form the decussating enamel rod patterns, for the prevention of ectopic mineral formation, and to maintain a functional DEJ. PMID:22243247

  6. Subsurface quality assurance practices

    International Nuclear Information System (INIS)

    1987-08-01

    This report addresses only the concept of applying Nuclear Quality Assurance (NQA) practices to repository shaft and subsurface design and construction; how NQA will be applied; and the level of detail required in the documentation for construction of a shaft and subsurface repository in contrast to the level of detail required in the documentation for construction of a traditional mine. This study determined that NQA practices are viable, attainable, as well as required. The study identified the appropriate NQA criteria and the repository's major structures, systems, items, and activities to which the criteria are applicable. A QA plan, for design and construction, and a list of documentation, for construction, are presented. 7 refs., 1 fig., 18 tabs

  7. Subsurface contaminants focus area

    International Nuclear Information System (INIS)

    1996-08-01

    The US Department of Enregy (DOE) Subsurface Contaminants Focus Area is developing technologies to address environmental problems associated with hazardous and radioactive contaminants in soil and groundwater that exist throughout the DOE complex, including radionuclides, heavy metals; and dense non-aqueous phase liquids (DNAPLs). More than 5,700 known DOE groundwater plumes have contaminated over 600 billion gallons of water and 200 million cubic meters of soil. Migration of these plumes threatens local and regional water sources, and in some cases has already adversely impacted off-site rsources. In addition, the Subsurface Contaminants Focus Area is responsible for supplying technologies for the remediation of numerous landfills at DOE facilities. These landfills are estimated to contain over 3 million cubic meters of radioactive and hazardous buried Technology developed within this specialty area will provide efective methods to contain contaminant plumes and new or alternative technologies for development of in situ technologies to minimize waste disposal costs and potential worker exposure by treating plumes in place. While addressing contaminant plumes emanating from DOE landfills, the Subsurface Contaminants Focus Area is also working to develop new or alternative technologies for the in situ stabilization, and nonintrusive characterization of these disposal sites

  8. Subsurface contaminants focus area

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-08-01

    The US Department of Enregy (DOE) Subsurface Contaminants Focus Area is developing technologies to address environmental problems associated with hazardous and radioactive contaminants in soil and groundwater that exist throughout the DOE complex, including radionuclides, heavy metals; and dense non-aqueous phase liquids (DNAPLs). More than 5,700 known DOE groundwater plumes have contaminated over 600 billion gallons of water and 200 million cubic meters of soil. Migration of these plumes threatens local and regional water sources, and in some cases has already adversely impacted off-site rsources. In addition, the Subsurface Contaminants Focus Area is responsible for supplying technologies for the remediation of numerous landfills at DOE facilities. These landfills are estimated to contain over 3 million cubic meters of radioactive and hazardous buried Technology developed within this specialty area will provide efective methods to contain contaminant plumes and new or alternative technologies for development of in situ technologies to minimize waste disposal costs and potential worker exposure by treating plumes in place. While addressing contaminant plumes emanating from DOE landfills, the Subsurface Contaminants Focus Area is also working to develop new or alternative technologies for the in situ stabilization, and nonintrusive characterization of these disposal sites.

  9. Effects of blue light irradiation on dental enamel remineralization in vitro; Avaliacao dos efeitos promovidos pela radiacao azul na remineralizacao do esmalte dentario in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Ilka Tiemy

    2009-07-01

    This study aimed to investigate the effects of blue radiation on dental enamel remineralization. In addition, a methodology of analysis was developed to evaluate alterations of enamel mineral content by optical coherence tomography. Artificial lesions were formed in bovine dental enamel slabs by immersing the samples in under saturated acetate buffer (2 mL/mm{sup 2} e 6.25 mL/mm{sup 2}). The lesions were irradiated with blue LED (l=455{+-}20nm), with radiant power of 110 mW, irradiance of 1.4 W/cm{sup 2}, radiant exposure of 13.8 J/{sup c}m2 and exposure time of 10 s. Remineralization was induced by pH-cycling model during 8 days. Cross-sectional hardness and optical coherence tomography (OCT) were used to assess mineral changes after remineralization. Hardness data showed that non-irradiated enamel lesions presented higher mineral content than irradiated ones and this difference was more evident in lesions formed in higher solution volume. The analysis of OCT signal also demonstrated that the mineral content of non-irradiated group was higher than in irradiated one; however, no significant difference was observed. Furthermore, significant differences in OCT sign were detected between sound and demineralized enamel. Based on the results obtained in the present study it can be concluded that blue radiation caused an inhibition of enamel remineralization. The methodology adopted for OCT analysis allowed the quantification of enamel mineral loss; however, the remineralization process could not be evaluated by this technique. (author)

  10. Dental enamel, fluorosis and amoxicillin

    Directory of Open Access Journals (Sweden)

    I. Ciarrocchi

    2012-06-01

    Full Text Available Introduction: Amoxicillin is one of the most used antibiotics among pediatric patients for the treatment of upper respiratory tract infections and specially for acute otitis media (AOM, a common diseases of infants and childhood. It has been speculated that the use of amoxicillin during early childhood could be associated with dental enamel fluorosis, also described in literature with the term Molar Incisor Hypomineralization (MIH, because they are generally situated in one or more 1st permanent molars and less frequently in the incisors. The effect of Amoxicillin seems to be independent of other risk factors such as fluoride intake, prematurity, hypoxia, hypocalcaemia, exposure to dioxins, chikenpox, otitis media, high fever and could have a significant impact on oral health for the wide use of this drug in that period of life. Objective: The aim of this work was to review the current literature about the association between amoxicillin and fluorosis. Methods and Results: A literature survey was done by applying the Medline database (Entrez PubMed; the Cochrane Library database of the Cochrane Collaboration (CENTRAL. The databases were searched using the following strategy and keywords: amoxicillin* AND (dental fluorosis* OR dental enamel* AND MIH*. After selecting the studies, only three relevant articles published between 1966 and 2011 were included in the review. Conclusion: The presence of several methodological issues does not allow to draw any evidence-based conclusions. No evidence of association was detected, therefore, there is a need of further well-designed studies to assess the scientific evidence of the relationship between amoxicillin and fluorosis and to restrict the prescription of this drug for recurrent upper respiratory tract infections especially acute otitis media (AOM during the first two years of life. When it is possible can be opportune to use an alternative antibiotic treatment.

  11. Enamel micromorphology of the tribosphenic molar

    OpenAIRE

    Hanousková, Pavla

    2014-01-01

    The tribosphenic molar is an ancestral type of mammalian teeth and a phy- lotypic stage of the mammalian dental evolution. Yet, in contrast to derived teeth types, its enamel microarchitecture attracted only little attention and the information on that subject is often restricted to statements suggesting a simple homogenous arrangement of a primitive radial prismatic enamel. The present paper tests this prediction with aid of comparative study of eight model species representing the orders Ch...

  12. EPR dosimetry with tooth enamel: A review

    International Nuclear Information System (INIS)

    Fattibene, Paola; Callens, Freddy

    2010-01-01

    When tooth enamel is exposed to ionizing radiation, radicals are formed, which can be detected using electron paramagnetic resonance (EPR) techniques. EPR dosimetry using tooth enamel is based on the (presumed) correlation between the intensity or amplitude of some of the radiation-induced signals with the dose absorbed in the enamel. In the present paper a critical review is given of this widely applied dosimetric method. The first part of the paper is fairly fundamental and deals with the main properties of tooth enamel and some of its model systems (e.g., synthetic apatites). Considerable attention is also paid to the numerous radiation-induced and native EPR signals and the radicals responsible for them. The relevant methods for EPR detection, identification and spectrum analyzing are reviewed from a general point of view. Finally, the needs for solid-state modelling and studies of the linearity of the dose response are investigated. The second part is devoted to the practical implementation of EPR dosimetry using enamel. It concerns specific problems of preparation of samples, their irradiation and spectrum acquisition. It also describes how the dosimetric signal intensity and dose can be retrieved from the EPR spectra. Special attention is paid to the energy dependence of the EPR response and to sources of uncertainties. Results of and problems encountered in international intercomparisons and epidemiological studies are also dealt with. In the final section the future of EPR dosimetry with tooth enamel is analyzed.

  13. Measurement of opalescence of tooth enamel.

    Science.gov (United States)

    Lee, Yong-Keun; Yu, Bin

    2007-08-01

    Opalescent dental esthetic restoratives look natural and esthetic in any light, react to light in the same manner as the natural tooth and show improved masking effect. The objective of this study was to determine the opalescence of tooth enamel with reflection spectrophotometers. Color of intact bovine and human enamel was measured in the reflectance and transmittance modes. Two kinds of spectrophotometers were used for bovine and one kind was used for human enamel. The opalescence parameter (OP) was calculated as the difference in yellow-blue color coordinate (CIE Deltab(*)) and red-green color coordinate (CIE Deltaa(*)) between the reflected and transmitted colors. Mean OP value of bovine enamel was 10.6 (+/-1.4) to 19.0 (+/-2.1), and varied by the configuration of spectrophotometers. Mean OP value of human enamel was 22.9 (+/-1.9). Opalescence varied by the configuration of measuring spectrophotometer and the species of enamel. These values could be used in the development of esthetic restorative materials.

  14. Potential of sub-ablative pulsed CO{sub 2} laser irradiation on inhibition of artificial caries-like lesion progress in bovine dental enamel; Potencial de inibicao da progressao da carie artificial por irradiacao sub-ablativa com laser de CO{sub 2} pulsado em esmalte dental bovino

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Marcella Esteves

    2005-07-01

    The aim of this study was to investigate whether sub-ablative pulsed C0{sub 2} laser (1 0,6 {mu}m) irradiation is capable of reducing the susceptibility of the dental enamel to demineralization, and thus achieving a potential caries-protective effect. The crowns of 51 bovine front teeth, embedded in acrylic resin and polished until exposure of flat enamel surface, were used. The samples were cut in cubes of 10x10 mm, and totally coated with acid-resistant nail varnish, except for an enamel exposed window of 16 mm square. Three groups (n=17) were obtained: control group (CG) not irradiated; group laser A (LA) and group laser B (LB) where the samples were irradiated. The conditions were 60 mJ, 100 Hz, 0,3 J/cm{sup 2} for LA and 135 mJ, 10 Hz, 0,7 J/cm{sup 2} for LB. Two samples of each group were submitted to SEM analysis and fifteen to demineralization in 3 ml acetate buffer solution (0,1 mol/L) with pH 4,5 for 24h at 37 deg C, with regular agitation. After the specimens were removed from the solution, the calcium and phosphorous content were measured with an inductively coupled plasma optical emission spectrometer and 2 more samples of each were submitted to SEM analysis. The obtained Ca and P means in {mu}g/ml and the calculated Ca/P molar ratio were: CG (367,88 {+-} 33,47; 168,91 {+-} 14,55; 1,70 {+-} 0,07) ; LA (372,70 {+-} 41,70; 161,46 {+-} 15,26; 1,79 {+-} 0,07) and LB (328,87 {+-} 24,91; 145,02 {+-} 11,04; 1,77 {+-} 0,05). The ANOVA statistical test revealed statistically significant difference for [Ca], [P] e Ca/P content between the groups (p<0,05). The Tukey test results showed that LB had significantly lower means of Ca and P content in demineralization solution than the other groups (p<0,01), and between LA and control there was not statistically significant difference. For the Ca/P molar ratio LA and LB means were significantly higher than the control (p<0,01) and there was not statistical difference between the two irradiated groups. SEM observations

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

    Directory of Open Access Journals (Sweden)

    Tae-Young Park

    2016-08-01

    Full Text Available 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.

  16. Effect of dentifrice containing fluoride and/or baking soda on enamel demineralization/remineralization: an in situ study.

    Science.gov (United States)

    Cury, J A; Hashizume, L N; Del Bel Cury, A A; Tabchoury, C P

    2001-01-01

    The additive effect of baking soda on the anticariogenic effect of fluoride dentifrice is not well established. To evaluate it, a crossover in situ study was done in three phases of 28 days. Volunteers, using acrylic palatal appliances containing four human enamel blocks, two sound (to evaluate demineralization) and two with artificial caries lesions (to evaluate remineralization), took part in this study. During each phase, 10% sucrose solution was dripped (3 times a day) only onto the sound blocks. After 10 min, a slurry of placebo, fluoride (F) or fluoride and baking soda (F+NaHCO(3)) dentifrice was dripped onto all enamel blocks. The results showed a higher F concentration in dental plaque formed during treatment with F+NaHCO(3) than placebo (pbaking soda neither improves nor impairs the effect of F dentifrice on reduction of demineralization and enhancement of remineralization of enamel.

  17. Subsurface Biogeochemistry of Actinides

    Energy Technology Data Exchange (ETDEWEB)

    Kersting, Annie B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Univ. Relations and Science Education; Zavarin, Mavrik [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Glenn T. Seaborg Inst.

    2016-06-29

    A major scientific challenge in environmental sciences is to identify the dominant processes controlling actinide transport in the environment. It is estimated that currently, over 2200 metric tons of plutonium (Pu) have been deposited in the subsurface worldwide, a number that increases yearly with additional spent nuclear fuel (Ewing et al., 2010). Plutonium has been shown to migrate on the scale of kilometers, giving way to a critical concern that the fundamental biogeochemical processes that control its behavior in the subsurface are not well understood (Kersting et al., 1999; Novikov et al., 2006; Santschi et al., 2002). Neptunium (Np) is less prevalent in the environment; however, it is predicted to be a significant long-term dose contributor in high-level nuclear waste. Our focus on Np chemistry in this Science Plan is intended to help formulate a better understanding of Pu redox transformations in the environment and clarify the differences between the two long-lived actinides. The research approach of our Science Plan combines (1) Fundamental Mechanistic Studies that identify and quantify biogeochemical processes that control actinide behavior in solution and on solids, (2) Field Integration Studies that investigate the transport characteristics of Pu and test our conceptual understanding of actinide transport, and (3) Actinide Research Capabilities that allow us to achieve the objectives of this Scientific Focus Area (SFA and provide new opportunities for advancing actinide environmental chemistry. These three Research Thrusts form the basis of our SFA Science Program (Figure 1).

  18. High and low torque handpieces: cutting dynamics, enamel cracking and tooth temperature.

    Science.gov (United States)

    Watson, T F; Flanagan, D; Stone, D G

    2000-06-24

    The aim of these experiments was to compare the cutting dynamics of high-speed high-torque (speed-increasing) and high-speed low-torque (air-turbine) handpieces and evaluate the effect of handpiece torque and bur type on sub-surface enamel cracking. Temperature changes were also recorded in teeth during cavity preparation with high and low torque handpieces with diamond and tungsten carbide (TC) burs. The null hypothesis of this study was that high torque handpieces cause more damage to tooth structure during cutting and lead to a rise in temperature within the pulp-chamber. Images of the dynamic interactions between burs and enamel were recorded at video rate using a confocal microscope. Central incisors were mounted on a specially made servomotor driven stage for cutting with a type 57 TC bur. The two handpiece types were used with simultaneous recording of cutting load and rate. Sub-surface enamel cracking caused by the use of diamond and TC burs with high and low torque was also examined. Lower third molars were sectioned horizontally to remove the cusp tips and then the two remaining crowns cemented together with cyanoacrylate adhesive, by their flat surfaces. Axial surfaces of the crowns were then prepared with the burs and handpieces. The teeth were then separated and the original sectioned surface examined for any cracks using a confocal microscope. Heat generation was measured using thermocouples placed into the pulp chambers of extracted premolars, with diamond and TC burs/high-low torque handpiece variables, when cutting occlusal and cervical cavities. When lightly loaded the two handpiece types performed similarly. However, marked differences in cutting mechanisms were noted when increased forces were applied to the handpieces with, generally, an increase in cutting rate. The air turbine could not cope with steady heavy loads, tending to stall. 'Rippling' was seen in the interface as this stall developed, coinciding with the bur 'clearing' itself. No

  19. An in vitro investigation of human enamel wear by restorative dental materials

    International Nuclear Information System (INIS)

    Adachi, L.K.; Saiki, M.; De Campos, T.N.

    2001-01-01

    A radiometric method was applied to asses enamel wear by another enamel and by restorative materials. The radioactive enamel was submitted to wear in a machine which allows sliding motion of an antagonistic surface in contact with the radioactive enamel. The enamel wear was evaluated by measuring the beta-activity of 32 P transferred to water from this irradiated tooth. Results obtained indicated that dental porcelains cause pronounced enamel wear when compared with that provoked by another natural enamel or by resin materials. Resin materials caused less enamel wear than another natural enamel. Vickers microhardness data obtained for antagonistic materials showed a correlation with the wear caused to the enamel. (author)

  20. Diffusion of fluoride in bovine enamel

    International Nuclear Information System (INIS)

    Flim, G.J.; Arends, J.; Kolar, Z.

    1976-01-01

    The uptake of 18 F and the penetration of both F and 18 F in bovine enamel was investigated. Sodium fluoride solutions buffered at pH 7 were employed. The uptake of 18 F was measured by a method described by R. Duckworth and M. Braden, Archs. Oral. Biol., 12(1967), pp. 217-230. The penetration concentration profiles of fluoride (F, 18 F) in the enamel were measured by a sectioning technique. The 18 F uptake in enamel was proportional to approximately tsup(3/4); t being the uptake time. The 18 F concentration as a function of the position in the enamel can be described by: c*(x,t) = c 0 *(t)exp[-α*(t)x]. After correction for the initial fluoride concentration in enamel, for unlabelled fluoride the same dependency is obtained. A model based on simultaneous diffusion and chemical reaction in the pores and diffusion into the hydroxyapatite crystallites will be presented. The results show that diffusion coefficients of the pores are approximately equal to 10 -10 cm 2 s -1 and in the apatite crystallites approximately equal to 10 -17 cm 2 s -1 . The limitations and the approximations of the model are discussed

  1. The fracture behaviour of dental enamel.

    Science.gov (United States)

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

    2010-01-01

    Enamel is the hardest tissue in the human body covering the crowns of teeth. Whereas the underlying dental material dentin is very well characterized in terms of mechanical and fracture properties, available data for enamel are quite limited and are apart from the most recent investigation mainly based on indentation studies. Within the current study, stable crack-growth experiments in bovine enamel have been performed, to measure fracture resistance curves for enamel. Single edge notched bending specimens (SENB) prepared out of bovine incisors were tested in 3-point bending and subsequently analysed using optical and environmental scanning electron microscopy. Cracks propagated primarily within the protein-rich rod sheaths and crack propagation occurred under an inclined angle to initial notch direction not only due to enamel rod and hydroxyapatite crystallite orientation but potentially also due to protein shearing. Determined mode I fracture resistance curves ranged from 0.8-1.5 MPa*m(1/2) at the beginning of crack propagation up to 4.4 MPa*m(1/2) at 500 microm crack extension; corresponding mode II values ranged from 0.3 to 1.5 MPa*m(1/2).

  2. Trace Elements in Human Tooth Enamel

    Energy Technology Data Exchange (ETDEWEB)

    Nixon, G. S. [Turner Dental School, University Of Manchester, Manchester (United Kingdom); Smith, H.; Livingston, H. D. [Department of Forensic Medicine, University Of Glasgow, Glasgow (United Kingdom)

    1967-10-15

    The trace elements are considered to play a role in the resistance of teeth to dental caries. The exact mechanism by which they act has not yet been fully established. Estimations of trace elements have been undertaken in sound human teeth. By means of activation analysis it has been possible to determine trace element concentrations in different layers of enamel in the same tooth. The concentrations of the following elements have been determined: arsenic, antimony, copper, zinc, manganese, mercury, molybdenum and vanadium. The distribution of trace elements in enamel varies from those with a narrow range, such as manganese, to those with a broad range, such as antimony. The elements present in the broad range are considered to be non-essential and their presence is thought to result from a chance incorporation into the enamel. Those in the narrow range appear to be essential trace elements and are present in amounts which do not vary unduly from other body tissues. Only manganese and zinc were found in higher concentrations in the surface layer of enamel compared with the inner layers. The importance of the concentration of trace elements on this surface layer of enamel is emphasized as this layer is the site of the first attack by the carious process. (author)

  3. The Effect of Casein Phosphopeptide-amorphous Calcium Fluoride Phosphate on the Remineralization of Artificial Caries Lesions: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Ngoc Vo Truong Nhu

    2017-08-01

    Full Text Available The studies on electron microstructure of the effect of the use of products that contain casein phosphopeptide-amorphous calcium fluoride phosphate (CPP-ACPF on enamel remineralization are still needed. It is important method to observe of the morphological changes of teeth in different conditions. Objective: To evaluate the remineralization potential of paste on enamel lesions using scanning electron microscopy (SEM. Methods: Sixty enamel specimens were prepared from extracted human premolars. The specimens were placed in a demineralizing solution for four days to produce artificial carious lesions. The specimens were then randomly assigned to two study groups: group A (control group and group B. Group B was incubated in remineralizing paste (CPP-ACPF for 30 minutes per day for 10 days. The control group received no intervention with remineralizing paste. All 60 specimens were stored in artificial saliva at 370C. After remineralization, the samples were observed using SEM. Results: The statistical analysis showed a decrease in the lesion area between the demineralized and remineralized samples, but no significant difference was observed in the lesion depth for group B. There was a significant increase observed in both the lesion depth and lesion area for group A (p = 0.03. Conclusion: The results showed the capacity of CPP-ACPF in supplying calcium and phosphate to the enamel, decreasing the dissolution of the enamel surface and increasing the remineralization of the enamel surface. 

  4. Enamel tissue engineering using subcultured enamel organ epithelial cells in combination with dental pulp cells.

    Science.gov (United States)

    Honda, Masaki J; Shinmura, Yuka; Shinohara, Yoshinori

    2009-01-01

    We describe a strategy for the in vitro engineering of enamel tissue using a novel technique for culturing enamel organ epithelial (EOE) cells isolated from the enamel organ using 3T3-J2 cells as a feeder layer. These subcultured EOE cells retain the capacity to produce enamel structures over a period of extended culture. In brief, enamel organs from 6-month-old porcine third molars were dissociated into single cells and subcultured on 3T3-J2 feeder cell layers. These subcultured EOE cells were then seeded onto a collagen sponge in combination with primary dental pulp cells isolated at an early stage of crown formation, and these constructs were transplanted into athymic rats. After 4 weeks, complex enamel-dentin structures were detected in the implants. These results show that our culture technique maintained ameloblast lineage cells that were able to produce enamel in vivo. This novel subculture technique provides an important tool for tooth tissue engineering. Copyright 2008 S. Karger AG, Basel.

  5. Morphology of the cemento-enamel junction in premolar teeth.

    Science.gov (United States)

    Arambawatta, Kapila; Peiris, Roshan; Nanayakkara, Deepthi

    2009-12-01

    The present study attempted to describe the distribution of the mineralized tissues that compose the cemento-enamel junction, with respect to both the different types of permanent premolars of males and females and the various surfaces of individual teeth. The cervical region of ground sections of 67 premolars that had been extracted for orthodontic reasons were analyzed using transmitted light microscopy to identify which of the following tissue interrelationships was present at the cemento-enamel junction: cementum overlapping enamel; enamel overlapping cementum; edge-to-edge relationship between cementum and enamel; or the presence of gaps between the enamel and cementum with exposed dentin. An edge-to-edge interrelation between root cementum and enamel was predominant (55.1%). In approximately one-third of the sample, gaps between cementum and enamel with exposed dentin were observed. Cementum overlapping enamel was less prevalent than previously reported, and enamel overlapping cementum was seen in a very small proportion of the sample. In any one tooth, the distribution of mineralized tissues at the cemento-enamel junction was irregular and unpredictable. The frequency of gaps between enamel and cementum with exposure of dentin was higher than previously reported, which suggests that this region is fragile and strongly predisposed to pathological changes. Hence, this region should be protected and carefully managed during routine clinical procedures such as dental bleaching, orthodontic treatment, and placement of restorative materials.

  6. Finite element analysis of the cyclic indentation of bilayer enamel

    International Nuclear Information System (INIS)

    Jia, Yunfei; Xuan, Fu-zhen; Chen, Xiaoping; Yang, Fuqian

    2014-01-01

    Tooth enamel is often subjected to repeated contact and often experiences contact deformation in daily life. The mechanical strength of the enamel determines the biofunctionality of the tooth. Considering the variation of the rod arrangement in outer and inner enamel, we approximate enamel as a bilayer structure and perform finite element analysis of the cyclic indentation of the bilayer structure, to mimic the repeated contact of enamel during mastication. The dynamic deformation behaviour of both the inner enamel and the bilayer enamel is examined. The material parameters of the inner and outer enamel used in the analysis are obtained by fitting the finite element results with the experimental nanoindentation results. The penetration depth per cycle at the quasi-steady state is used to describe the depth propagation speed, which exhibits a two-stage power-law dependence on the maximum indentation load and the amplitude of the cyclic load, respectively. The continuous penetration of the indenter reflects the propagation of the plastic zone during cyclic indentation, which is related to the energy dissipation. The outer enamel serves as a protective layer due to its great resistance to contact deformation in comparison to the inner enamel. The larger equivalent plastic strain and lower stresses in the inner enamel during cyclic indentation, as calculated from the finite element analysis, indicate better crack/fracture resistance of the inner enamel. (paper)

  7. Finite element analysis of the cyclic indentation of bilayer enamel

    Science.gov (United States)

    Jia, Yunfei; Xuan, Fu-zhen; Chen, Xiaoping; Yang, Fuqian

    2014-04-01

    Tooth enamel is often subjected to repeated contact and often experiences contact deformation in daily life. The mechanical strength of the enamel determines the biofunctionality of the tooth. Considering the variation of the rod arrangement in outer and inner enamel, we approximate enamel as a bilayer structure and perform finite element analysis of the cyclic indentation of the bilayer structure, to mimic the repeated contact of enamel during mastication. The dynamic deformation behaviour of both the inner enamel and the bilayer enamel is examined. The material parameters of the inner and outer enamel used in the analysis are obtained by fitting the finite element results with the experimental nanoindentation results. The penetration depth per cycle at the quasi-steady state is used to describe the depth propagation speed, which exhibits a two-stage power-law dependence on the maximum indentation load and the amplitude of the cyclic load, respectively. The continuous penetration of the indenter reflects the propagation of the plastic zone during cyclic indentation, which is related to the energy dissipation. The outer enamel serves as a protective layer due to its great resistance to contact deformation in comparison to the inner enamel. The larger equivalent plastic strain and lower stresses in the inner enamel during cyclic indentation, as calculated from the finite element analysis, indicate better crack/fracture resistance of the inner enamel.

  8. Effects of hydrogen peroxide bleaching strips on tooth surface color, surface microhardness, surface and subsurface ultrastructure, and microchemical (Raman spectroscopic) composition.

    Science.gov (United States)

    Duschner, Heinz; Götz, Hermann; White, Donald J; Kozak, Kathleen M; Zoladz, James R

    2006-01-01

    This study examined the effects of hydrogen peroxide tooth bleaching strips on the surface hardness and morphology of enamel and the ultrastructure and chemical composition of enamel and dentin in vitro. Sound human molars were ground and polished to prepare a uniform substrate for bleaching treatments. A cycling treatment methodology was employed which alternated ex vivo human salivary exposures with bleaching treatments under conditions of controlled temperature and durations of treatment. Bleaching treatments included commercial Crest Whitestrips bleaching strips, which utilize hydrogen peroxide in a gel as the in situ bleaching source at 6.0 and 6.5% concentrations of H2O2. Control treatments included an untreated group. Crest Whitestrips bleaching included treatment exposures simulating 2x the recommended clinical exposures (28 hours bleaching). Surface color measurements were taken prior to and following bleaching to ensure tooth bleaching activity. The effects of bleach on physical properties of enamel were assessed with microhardness measures. Ultrastructural effects were classified by surface and subsurface confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) techniques. In addition, the effects of bleaching on tooth microchemical composition was studied in different tooth regions by coincident assessment of Raman spectroscopic signature. Color assessments confirmed significant ex vivo tooth bleaching by Whitestrips. Surface microhardness and SEM measures revealed no deleterious effects on the enamel surfaces. CLSM micromorphological assessments supported the safety of hydrogen peroxide bleaching strips both on surface and subsurface enamel, DEJ, and dentin ultrastructure. Raman spectroscopy analysis demonstrated no obvious effects of bleaching treatments on the microchemical composition of enamel and dentin. These results confirm that tooth bleaching with hydrogen peroxide whitening strips does not produce changes in surface/subsurface

  9. Ph-activated nano-amorphous calcium phosphate-based cement to reduce dental enamel demineralization.

    Science.gov (United States)

    Melo, Mary A S; Weir, Michael D; Passos, Vanara F; Powers, Michael; Xu, Hockin H K

    2017-12-01

    Enamel demineralization is destructive, esthetically compromised, and costly complications for orthodontic patients. Nano-sized amorphous calcium phosphate (NACP) has been explored to address this challenge. The 20% NACP-loaded ortho-cement notably exhibited favorable behavior on reducing demineralization of enamel around brackets in a caries model designed to simulate the carious attack. The 20% NACP-loaded ortho-cement markedly promotes higher calcium and phosphate release at a low pH, and the mineral loss was almost two fold lower and carious lesion depth decreased the by 1/3. This novel approach is promising co-adjuvant route for prevention of dental caries dissemination in millions of patients under orthodontic treatment.

  10. Micro-PIXE (proton-induced X-ray emission) study of the effects of fluoride on mineral distribution patterns in enamel and dentin in the developing hamster tooth germ

    International Nuclear Information System (INIS)

    Lyaruu, D.M.; Tros, G.H.; Bronckers, A.L.; Woeltgens, J.H.

    1990-01-01

    Micro-PIXE (proton-induced X-ray emission) analysis was performed on unfixed and anhydrously prepared sections from developing enamel and dentin from hamsters injected with a single dose of 20 mg NaF/kg body weight. Fluoride, apart from inducing the formation of the characteristic paired response in the enamel (i.e., a hyper- followed by a hypomineralized band in the secretory enamel), also induces the formation of sub-ameloblastic cystic lesions under the transitional and early secretory enamel accompanied by relatively intense hypermineralization of the underlying cystic enamel surface. These cystic lesions, however, were only found to be associated with certain isolated populations of these cells. In addition, these lesions were restricted to the smooth surfaces of the tooth germ only. Cystic lesions such as those seen under the transitional and early secretory ameloblasts were not observed under the fully secretory or maturation stage ameloblasts. Why fluoride induces the formation of cystic lesions in some ameloblast populations while other cells in the same stage of development apparently remain unaffected, is a matter which needs further investigation

  11. Subsurface Ventilation System Description Document

    Energy Technology Data Exchange (ETDEWEB)

    Eric Loros

    2001-07-25

    The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

  12. Subsurface Ventilation System Description Document

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-10-12

    The Subsurface Ventilation System supports the construction and operation of the subsurface repository by providing air for personnel and equipment and temperature control for the underground areas. Although the system is located underground, some equipment and features may be housed or located above ground. The system ventilates the underground by providing ambient air from the surface throughout the subsurface development and emplacement areas. The system provides fresh air for a safe work environment and supports potential retrieval operations by ventilating and cooling emplacement drifts. The system maintains compliance within the limits established for approved air quality standards. The system maintains separate ventilation between the development and waste emplacement areas. The system shall remove a portion of the heat generated by the waste packages during preclosure to support thermal goals. The system provides temperature control by reducing drift temperature to support potential retrieval operations. The ventilation system has the capability to ventilate selected drifts during emplacement and retrieval operations. The Subsurface Facility System is the main interface with the Subsurface Ventilation System. The location of the ducting, seals, filters, fans, emplacement doors, regulators, and electronic controls are within the envelope created by the Ground Control System in the Subsurface Facility System. The Subsurface Ventilation System also interfaces with the Subsurface Electrical System for power, the Monitored Geologic Repository Operations Monitoring and Control System to ensure proper and safe operation, the Safeguards and Security System for access to the emplacement drifts, the Subsurface Fire Protection System for fire safety, the Emplacement Drift System for repository performance, and the Backfill Emplacement and Subsurface Excavation Systems to support ventilation needs.

  13. Novel Dental Cement to Combat Biofilms and Reduce Acids for Orthodontic Applications to Avoid Enamel Demineralization

    Directory of Open Access Journals (Sweden)

    Ning Zhang

    2016-05-01

    Full Text Available Orthodontic treatments often lead to biofilm buildup and white spot lesions due to enamel demineralization. The objectives of this study were to develop a novel bioactive orthodontic cement to prevent white spot lesions, and to determine the effects of cement compositions on biofilm growth and acid production. 2-methacryloyloxyethyl phosphorylcholine (MPC, nanoparticles of silver (NAg, and dimethylaminohexadecyl methacrylate (DMAHDM were incorporated into a resin-modified glass ionomer cement (RMGI. Enamel shear bond strength (SBS was determined. Protein adsorption was determined using a micro bicinchoninic acid method. A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate metabolic activity, colony-forming units (CFU and lactic acid production. Incorporating 3% of MPC, 1.5% of DMAHDM, and 0.1% of NAg into RMGI, and immersing in distilled water at 37 °C for 30 days, did not decrease the SBS, compared to control (p > 0.1. RMGI with 3% MPC + 1.5% DMAHDM + 0.1% NAg had protein amount that was 1/10 that of control. RMGI with triple agents (MPC + DMAHDM + NAg had much stronger antibacterial property than using a single agent or double agents (p < 0.05. Biofilm CFU on RMGI with triple agents was reduced by more than 3 orders of magnitude, compared to commercial control. Biofilm metabolic activity and acid production were also greatly reduced. In conclusion, adding MPC + DMAHDM + NAg in RMGI substantially inhibited biofilm viability and acid production, without compromising the orthodontic bracket bond strength to enamel. The novel bioactive cement is promising for orthodontic applications to hinder biofilms and plaque buildup and enamel demineralization.

  14. Enamel alteration following tooth bleaching and remineralization.

    Science.gov (United States)

    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. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  15. Thermal induced EPR signals in tooth enamel

    International Nuclear Information System (INIS)

    Fattibene, P.; Aragno, D.; Onori, S.; Pressello, M.C.

    2000-01-01

    Electron paramagnetic resonance (EPR) spectroscopy was used to detect the effects of temperature on powdered human tooth enamel, not irradiated in the laboratory. Samples were heated at temperature between 350 and 450, at 600 and at 1000 deg. C, for different heating times, between 6 min and 39 h. Changes in the EPR spectra were detected, with the formation of new signals. Possible correlation between the changes in EPR spectra and modifications in the enamel and in the mineral phase of bone detected with other techniques is discussed. The implications for dosimetric applications of signals induced by overheating due to mechanical friction during sample preparation are underlined

  16. Subsurface Facility System Description Document

    International Nuclear Information System (INIS)

    Eric Loros

    2001-01-01

    The Subsurface Facility System encompasses the location, arrangement, size, and spacing of the underground openings. This subsurface system includes accesses, alcoves, and drifts. This system provides access to the underground, provides for the emplacement of waste packages, provides openings to allow safe and secure work conditions, and interfaces with the natural barrier. This system includes what is now the Exploratory Studies Facility. The Subsurface Facility System physical location and general arrangement help support the long-term waste isolation objectives of the repository. The Subsurface Facility System locates the repository openings away from main traces of major faults, away from exposure to erosion, above the probable maximum flood elevation, and above the water table. The general arrangement, size, and spacing of the emplacement drifts support disposal of the entire inventory of waste packages based on the emplacement strategy. The Subsurface Facility System provides access ramps to safely facilitate development and emplacement operations. The Subsurface Facility System supports the development and emplacement operations by providing subsurface space for such systems as ventilation, utilities, safety, monitoring, and transportation

  17. Retrospective individual dosimetry using EPR of tooth enamel

    International Nuclear Information System (INIS)

    Skvortzo, V.; Ivannikov, A.; Stepanenko, V.; Wieser, A.; Bougai, A.; Brick, A.; Chumak, V.; Radchuk, V.; Repin, V.; Kirilov, V.

    1996-01-01

    The results of joint investigations (in the framework of ECP-10 program) aimed on the improvement of the sensitivity and accuracy of the procedure of dose measurement using tooth enamel EPR spectroscopy are presented. It is shown, what the sensitivity of method may be increased using special physical-chemical procedure of the enamel samples treatment, which leads to the reducing of EPR signal of organic components in enamel. Tooth diseases may have an effect on radiation sensitivity of enamel. On the basis of statistical analysis of the results of more then 2000 tooth enamel samples measurements it was shown, what tooth enamel EPR spectroscopy gives opportunity to register contribution into total dose, which is caused by natural environmental radiation and by radioactive contamination. EPR response of enamel to ultraviolet exposure is investigated and possible influences to EPR dosimetry is discussed. The correction factors for EPR dosimetry in real radiation fields are estimated

  18. Size dependent elastic modulus and mechanical resilience of dental enamel.

    Science.gov (United States)

    O'Brien, Simona; Shaw, Jeremy; Zhao, Xiaoli; Abbott, Paul V; Munroe, Paul; Xu, Jiang; Habibi, Daryoush; Xie, Zonghan

    2014-03-21

    Human tooth enamel exhibits a unique microstructure able to sustain repeated mechanical loading during dental function. Although notable advances have been made towards understanding the mechanical characteristics of enamel, challenges remain in the testing and interpretation of its mechanical properties. For example, enamel was often tested under dry conditions, significantly different from its native environment. In addition, constant load, rather than indentation depth, has been used when mapping the mechanical properties of enamel. In this work, tooth specimens are prepared under hydrated conditions and their stiffnesses are measured by depth control across the thickness of enamel. Crystal arrangement is postulated, among other factors, to be responsible for the size dependent indentation modulus of enamel. Supported by a simple structure model, effective crystal orientation angle is calculated and found to facilitate shear sliding in enamel under mechanical contact. In doing so, the stress build-up is eased and structural integrity is maintained. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Targeted p120-catenin ablation disrupts dental enamel development

    DEFF Research Database (Denmark)

    Bartlett, John D; Dobeck, Justine M; Tye, Coralee E

    2010-01-01

    Dental enamel development occurs in stages. The ameloblast cell layer is adjacent to, and is responsible for, enamel formation. When rodent pre-ameloblasts become tall columnar secretory-stage ameloblasts, they secrete enamel matrix proteins, and the ameloblasts start moving in rows that slide...... by one another. This movement is necessary to form the characteristic decussating enamel prism pattern. Thus, a dynamic system of intercellular interactions is required for proper enamel development. Cadherins are components of the adherens junction (AJ), and they span the cell membrane to mediate...... attachment to adjacent cells. p120 stabilizes cadherins by preventing their internalization and degradation. So, we asked if p120-mediated cadherin stability is important for dental enamel formation. Targeted p120 ablation in the mouse enamel organ had a striking effect. Secretory stage ameloblasts detached...

  20. Regulated fracture in tooth enamel: a nanotechnological strategy from nature.

    Science.gov (United States)

    Ghadimi, Elnaz; Eimar, Hazem; Song, Jun; Marelli, Benedetto; Ciobanu, Ovidiu; Abdallah, Mohamed-Nur; Stähli, Christoph; Nazhat, Showan N; Vali, Hojatollah; Tamimi, Faleh

    2014-07-18

    Tooth enamel is a very brittle material; however it has the ability to sustain cracks without suffering catastrophic failure throughout the lifetime of mechanical function. We propose that the nanostructure of enamel can play a significant role in defining its unique mechanical properties. Accordingly we analyzed the nanostructure and chemical composition of a group of teeth, and correlated it with the crack resistance of the same teeth. Here we show how the dimensions of apatite nanocrystals in enamel can affect its resistance to crack propagation. We conclude that the aspect ratio of apatite nanocrystals in enamel determines its resistance to crack propagation. According to this finding, we proposed a new model based on the Hall-Petch theory that accurately predicts crack propagation in enamel. Our new biomechanical model of enamel is the first model that can successfully explain the observed variations in the behavior of crack propagation of tooth enamel among different humans. Copyright © 2014 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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

  2. Helium ion microscopy of enamel crystallites and extracellular tooth enamel matrix.

    Science.gov (United States)

    Bidlack, Felicitas B; Huynh, Chuong; Marshman, Jeffrey; Goetze, Bernhard

    2014-01-01

    An unresolved problem in tooth enamel studies has been to analyze simultaneously and with sufficient spatial resolution both mineral and organic phases in their three dimensional (3D) organization in a given specimen. This study aims to address this need using high-resolution imaging to analyze the 3D structural organization of the enamel matrix, especially amelogenin, in relation to forming enamel crystals. Chemically fixed hemi-mandibles from wild type mice were embedded in LR White acrylic resin, polished and briefly etched to expose the organic matrix in developing tooth enamel. Full-length amelogenin was labeled with specific antibodies and 10 nm immuno-gold. This allowed us to use and compare two different high-resolution imaging techniques for the analysis of uncoated samples. Helium ion microscopy (HIM) was applied to study the spatial organization of organic and mineral structures, while field emission scanning electron microscopy (FE-SEM) in various modes, including backscattered electron detection, allowed us to discern the gold-labeled proteins. Wild type enamel in late secretory to early maturation stage reveals adjacent to ameloblasts a lengthwise parallel alignment of the enamel matrix proteins, including full-length amelogenin proteins, which then transitions into a more heterogeneous appearance with increasing distance from the mineralization front. The matrix adjacent to crystal bundles forms a smooth and lacey sheath, whereas between enamel prisms it is organized into spherical components that are interspersed with rod-shaped protein. These findings highlight first, that the heterogeneous organization of the enamel matrix can be visualized in mineralized en bloc samples. Second, our results illustrate that the combination of these techniques is a powerful approach to elucidate the 3D structural organization of organic matrix molecules in mineralizing tissue in nanometer resolution.

  3. Helium ion microscopy of enamel crystallites and extracellular tooth enamel matrix

    Directory of Open Access Journals (Sweden)

    Felicitas B Bidlack

    2014-10-01

    Full Text Available An unresolved problem in tooth enamel studies has been to analyze simultaneously and with sufficient spatial resolution both mineral and organic phases in their three dimensional (3D organization in a given specimen. This study aims to address this need using high-resolution imaging to analyze the 3D structural organization of the enamel matrix, especially amelogenin, in relation to forming enamel crystals. Chemically fixed hemi-mandibles from wild type mice were embedded in LR White acrylic resin, polished and briefly etched to expose the organic matrix in developing tooth enamel. Full-length amelogenin was labeled with specific antibodies and 10 nm immuno-gold. This allowed us to use and compare two different high-resolution imaging techniques for the analysis of uncoated samples. Helium ion microscopy (HIM was applied to study the spatial organization of organic and mineral structures, while field emission scanning electron microscopy (FE-SEM in various modes, including backscattered electron detection, allowed us to discern the gold-labeled proteins. Wild type enamel in late secretory to early maturation stage reveals adjacent to ameloblasts a lengthwise parallel alignment of the enamel matrix proteins, including full-length amelogenin proteins, which then transitions into a more heterogeneous appearance with increasing distance from the mineralization front. The matrix adjacent to crystal bundles forms a smooth and lacey sheath, whereas between enamel prisms it is organized into spherical components that are interspersed with rod-shaped protein. These findings highlight first, that the heterogeneous organization of the enamel matrix can be visualized in mineralized en bloc samples. Second, our results illustrate that the combination of these techniques is a powerful approach to elucidate the 3D structural organization of organic matrix molecules in mineralizing tissue in nanometer resolution.

  4. Subsurface remote sensing

    International Nuclear Information System (INIS)

    Schweitzer, Jeffrey S.; Groves, Joel L.

    2002-01-01

    Subsurface remote sensing measurements are widely used for oil and gas exploration, for oil and gas production monitoring, and for basic studies in the earth sciences. Radiation sensors, often including small accelerator sources, are used to obtain bulk properties of the surrounding strata as well as to provide detailed elemental analyses of the rocks and fluids in rock pores. Typically, instrument packages are lowered into a borehole at the end of a long cable, that may be as long as 10 km, and two-way data and instruction telemetry allows a single radiation instrument to operate in different modes and to send the data to a surface computer. Because these boreholes are often in remote locations throughout the world, the data are frequently transmitted by satellite to various locations around the world for almost real-time analysis and incorporation with other data. The complete system approach that permits rapid and reliable data acquisition, remote analysis and transmission to those making decisions is described

  5. AmF/NaF/SnCl2 solution reduces in situ enamel erosion – profilometry and cross-sectional nanoindentation analysis

    Directory of Open Access Journals (Sweden)

    Thayanne Monteiro RAMOS-OLIVEIRA

    2017-03-01

    Full Text Available Abstract This in situ study aimed to investigate the effect of a tin-containing fluoride solution in preventing enamel erosion. Also, its effects on the partly demineralized zone were assessed for the first time. Thirteen volunteers participated in this 2-phase study, wearing removable intra-oral appliances containing four sterilized bovine enamel slabs, for 8 days, where 2 treatment protocols were tested using samples in replicas (n = 13: CO - no treatment (negative control and FL - AmF/NaF/SnCl2 solution (500 ppm F-, 800 ppm Sn2+, pH = 4.5. Samples were daily exposed to an erosive challenge (0.65% citric acid, pH 3.6, 4 min, 2x/day. In the 2nd phase, volunteers switched to the other treatment protocol. Samples were evaluated for surface loss using a profilometer (n = 13 and a cross-sectional nanohardness (CSNH test (n = 13 was carried out in order to determine how deep the partly demineralized zone reaches below the erosive lesion. The data were statistically analyzed by two-way ANOVA. Erosive challenges lead to smaller enamel surface loss (p < 0.001 in the FL group when compared to group CO. Data from CSNH showed that there was no significant difference in demineralized enamel zone underneath erosion lesions between the groups. An amorphous layer could be observed on the surface of enamel treated with tin-containing solution alone. Under the experimental conditions of this in situ study, it can be concluded that AmF/NaF/SnCl2 solution prevents enamel surface loss but does not change the hardness of the partly demineralized zone near-surface enamel.

  6. Deformation behavior of human enamel and dentin-enamel junction under compression.

    Science.gov (United States)

    Zaytsev, Dmitry; Panfilov, Peter

    2014-01-01

    Deformation behavior under uniaxial compression of human enamel and dentin-enamel junction (DEJ) is considered in comparison with human dentin. This deformation scheme allows estimating the total response from all levels of the hierarchical composite material in contrast with the indentation, which are limited by the mesoscopic and microscopic scales. It was shown for the first time that dental enamel is the strength (up to 1850MPa) hard tissue, which is able to consider some elastic (up to 8%) and plastic (up to 5%) deformation under compression. In so doing, it is almost undeformable substance under the creep condition. Mechanical properties of human enamel depend on the geometry of sample. Human dentin exhibits the similar deformation behavior under compression, but the values of its elasticity (up to 40%) and plasticity (up to 18%) are much more, while its strength (up to 800MPa) is less in two times. Despite the difference in mechanical properties, human enamel is able to suppress the cracking alike dentin. Deformation behavior under the compression of the samples contained DEJ as the same to dentin. This feature allows a tooth to be elastic-plastic (as dentin) and wear resistible (as enamel), simultaneously. © 2013 Elsevier B.V. All rights reserved.

  7. Effect of CPP-ACP paste with and without CO2 laser irradiation on demineralized enamel microhardness and bracket shear bond strength

    Directory of Open Access Journals (Sweden)

    Nasrin Farhadian

    Full Text Available ABSTRACT Introduction: Many patients seeking orthodontic treatment already have incipient enamel lesions and should be placed under preventive treatments. The aim of this in vitro study was to evaluate the effect of CPP-ACP paste and CO2 laser irradiation on demineralized enamel microhardness and shear bond strength of orthodontic brackets. Methods: Eighty caries-free human premolars were subjected to a demineralization challenge using Streptococcus mutans. After demineralization, the samples were randomly divided into five equal experimental groups: Group 1 (control, the brackets were bonded without any surface treatment; Group 2, the enamel surfaces were treated with CPP-ACP paste for 4 minutes before bonding; Group 3, the teeth were irradiated with CO2 laser beams at a wavelength of 10.6 µm for 20 seconds. The samples in Groups 4 and 5 were treated with CO2 laser either before or through CPP-ACP application. SEM photomicrographs of a tooth from each group were taken to observe the enamel surface. The brackets were bonded to the buccal enamel using a conventional method. Shear bond strength of brackets and ARI scores were measured. Vickers microhardness was measured on the non-bonded enamel surface. Data were analyzed with ANOVA and Tukey test at the p< 0.05 level. Results: The mean shear bond strength and microhardness of the laser group were higher than those in the control group and this difference was statistically significant (p< 0.05. All groups showed a higher percentage of ARI score 4. Conclusion: CO2 laser at a wavelength of 10.6 µm significantly increased demineralized enamel microhardness and enhanced bonding to demineralized enamel.

  8. Nanoindentation creep behavior of human enamel.

    Science.gov (United States)

    He, Li-Hong; Swain, Michael V

    2009-11-01

    In this study, the indentation creep behavior of human enamel was investigated with a nanoindentation system and a Berkovich indenter at a force of 250 mN with one-step loading and unloading method. A constant hold period of 900 s was incorporated into each test at the maximum load as well at 5 mN minimum load during unloading. The indentation creep at the maximum load and creep recovery at the minimum load was described with a double exponential function and compared with other classic viscoelastic models (Debye/Maxwell and Kohlrausch-Williams-Watts). Indentation creep rate sensitivity, m, of human enamel was measured for the first time with a value of approximately 0.012. Enamel displayed both viscoelastic and viscoplastic behavior similar to that of bone. These results indicate that, associated with entrapment of particulates between teeth under functional loading and sliding wear conditions, the enamel may inelastically deform but recover upon its release. This behavior may be important in explaining the excellent wear resistance, antifatigue, and crack resistant abilities of natural tooth structure. (c) 2008 Wiley Periodicals, Inc.

  9. Tooth enamel hypoplasia in PHACE syndrome.

    Science.gov (United States)

    Chiu, Yvonne E; Siegel, Dawn H; Drolet, Beth A; Hodgson, Brian D

    2014-01-01

    Individuals with PHACE syndrome (posterior fossa malformations, hemangiomas, arterial anomalies, cardiac defects, eye abnormalities, sternal cleft, and supraumbilical raphe syndrome) have reported dental abnormalities to their healthcare providers and in online forums, but dental involvement has not been comprehensively studied. A study was conducted at the third PHACE Family Conference, held in Milwaukee, Wisconsin, in July 2012. A pediatric dentist examined subjects at enrollment. Eighteen subjects were enrolled. The median age was 4.2 years (range 9 mos-9 yrs; 14 girls, 4 boys). Eleven of 18 patients had intraoral hemangiomas and five of these (50%) had hypomature enamel hypoplasia. None of the seven patients without intraoral hemangiomas had enamel hypoplasia. No other dental abnormalities were seen. Enamel hypoplasia may be a feature of PHACE syndrome when an intraoral hemangioma is present. Enamel hypoplasia increases the risk of caries, and clinicians should refer children with PHACE syndrome to a pediatric dentist by 1 year of age. © 2014 Wiley Periodicals, Inc.

  10. Microtensile bond strength of enamel after bleaching.

    Science.gov (United States)

    Lago, Andrea Dias Neves; Garone-Netto, Narciso

    2013-01-01

    To evaluate the bond strength of a composite resin to the bovine enamel bleached with 35% hydrogen peroxide. It was used an etching-and-rinse adhesive system employed immediately, 7 and 14 days after the bleaching. Twenty bovine teeth were randomly distributed into 4 groups (n = 5), 3 experimental and 1 control. G1: Unbleached + restoration 14 days after storage in artificial saliva (control); G2: Bleached + restoration immediately after bleaching; G3: Bleached + restoration 7 days after bleaching; G4: Bleached + restoration 14 days after bleaching. Their buccal enamel surfaces were flattened, and a 25 mm² (5 × 5 mm) area from each one of these regions was outlined so as to standardize the experimental region. Universal hybrid composite resin Filtek™Z350 was inserted into four layers of 1 mm each and photo-activated. The bond strength was quantitatively evaluated by a microtensile test (1.0 mm/min) 24 h after the restorative procedures. The failure mode was assessed through scanning electron microscopy (SEM). There was a significant reduction in the bond strength of the restored teeth immediately after the bleaching (G2). There were no significant differences in enamel bond strength between groups G1, G3, and G4. There was a predominance of adhesive and mixed (cohesive + adhesive) failure in all groups. The 7-day-period after the end of the bleaching with 35% hydrogen peroxide was enough to achieve the appropriate values of bond strength to the enamel.

  11. Assessment of cavitation in artificial approximal dental lesions with near-IR imaging

    Science.gov (United States)

    Simon, Jacob C.; Darling, Cynthia L.; Fried, Daniel

    2017-02-01

    Bitewing radiography is still considered state-of-the-art diagnostic technology for assessing cavitation within approximal carious dental lesions, even though radiographs cannot resolve cavitated surfaces but instead are used to measure lesion depth in order to predict cavitation. Clinicians need new technologies capable of determining whether approximal carious lesions have become cavitated because not all lesions progress to cavitation. Assessing lesion cavitation from near-infrared (NIR) imaging methods holds great potential due to the high transparency of enamel in the NIR region from λ=1300-1700-nm, which allows direct visualization and quantified measurements of enamel demineralization. The objective of this study was to measure the change in lesion appearance between non-cavitated and cavitated lesions in artificially generated lesions using NIR imaging modalities (two-dimensional) at λ=1300-nm and λ=1450-nm and cross-polarization optical coherence tomography (CP-OCT) (thee-dimensional) λ=1300-nm. Extracted human posterior teeth with sound proximal surfaces were chosen for this study and imaged before and after artificial lesions were made. A high speed dental hand piece was used to create artificial cavitated proximal lesions in sound samples and imaged. The cavitated artificial lesions were then filled with hydroxyapatite powder to simulate non-cavitated proximal lesions.

  12. Effect of Argon Laser on Enamel Demineralization around Orthodontic Brackets: An In Vitro Study

    Science.gov (United States)

    Miresmaeili, Amirfarhang; Etrati Khosroshahi, Mohammad; Motahary, Pouya; Rezaei-Soufi, Loghman; Mahjub, Hossein; Dadashi, Maryam; Farhadian, Nasrin

    2014-01-01

    Objective This study was designed to evaluate the effect of argon laser irradiation on development and progress of enamel demineralization around orthodontic brackets. Materials and Methods: Fifty caries-free, intact human premolars were randomly assigned to one of the following five equal groups: Groups 1 (control) and 2: The brackets were bonded using conventional halogen light for 40s and argon laser for 10s, respectively. Teeth in group 3 were lased with argon laser for 10s before bracket bonding with halogen light. Group 4 was the same as group 3 except that brackets were also bonded with argon laser. In group 5 samples were bonded conventionally, immersed in an artificial caries solution for two days and then irradiated for 10s with argon laser. All samples were subjected to demineralization by artificial caries solution for 10 days. After bracket removal, samples were buccolingually sectioned and evaluated by polarized light microscopy. Decalcified lesion depth in each section was measured by a trained examiner in a blind fashion. Data were analyzed in SPSS 14 using one-way ANOVA and Tukey’s HSD post hoc test. Results: The control group showed the greatest mean lesion depth while group 5 revealed the lowest. The laser-treated groups had significantly lower mean lesion depth compared with the control group (Pbracket bonding can increase caries resistance of intact and demineralized enamel. PMID:25584052

  13. Ectopic expression of dentin sialoprotein during amelogenesis hardens bulk enamel.

    Science.gov (United States)

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

    2007-02-23

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

  14. The molecular basis of hereditary enamel defects in humans.

    Science.gov (United States)

    Wright, J T; 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. © International & American Associations for

  15. The Molecular Basis of Hereditary Enamel Defects in Humans

    Science.gov (United States)

    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

  16. Effects of ultrasonic instrumentation on enamel surfaces with various defects.

    Science.gov (United States)

    Kim, S-Y; Kang, M-K; Kang, S-M; Kim, H-E

    2018-05-01

    The aim of this study was to analyse the enamel damage caused by ultrasonic scaling of teeth with various enamel conditions that are difficult to identify by visual inspection, such as enamel cracks, early caries and resin restorations. In total, 120 tooth surfaces were divided into 4 experimental groups using a quantitative light-induced fluorescence-digital system: sound enamel group, enamel cracks group, early caries group and resin restoration group. A skilled dental hygienist performed ultrasonic scaling under a standardized set of conditions: a ≤ 15° angle between the scaler tip and tooth surface and 40-80 g of lateral pressure at the rate of 12 times/10 s. Following scaling, the depth of enamel damage was measured using a surface profilometer and observed using scanning electron microscopy (SEM). The damage depth was the greatest in the enamel cracks group (37.63 ± 34.42 μm), followed by the early caries group (26.81 ± 8.67 μm), resin restoration group (19.63 ± 6.73 μm) and the sound enamel group (17.00 ± 5.66 μm). The damage depth was significantly deeper in the enamel cracks and early caries groups than in the sound enamel group (P enamel loss in the enamel cracks, early caries and resin restoration groups. The results of this study suggest that ultrasonic scaling can cause further damage to teeth with enamel cracks, early caries and resin restorations. Therefore, accurate identification of tooth conditions and calculus before the initiation of ultrasonic scaling is necessary to minimize damage. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Near-UV laser treatment of extrinsic dental enamel stains.

    Science.gov (United States)

    Schoenly, J E; Seka, W; Featherstone, J D B; Rechmann, P

    2012-04-01

    The selective ablation of extrinsic dental enamel stains using a 400-nm laser is evaluated at several fluences for completely removing stains with minimal damage to the underlying enamel. A frequency-doubled Ti:sapphire laser (400-nm wavelength, 60-nanosecond pulse duration, 10-Hz repetition rate) was used to treat 10 extracted human teeth with extrinsic enamel staining. Each tooth was irradiated perpendicular to the surface in a back-and-forth motion over a 1-mm length using an ∼300-µm-diam 10th-order super-Gaussian beam with fluences ranging from 0.8 to 6.4 J/cm(2) . Laser triangulation determined stain depth and volume removed by measuring 3D surface images before and after irradiation. Scanning electron microscopy evaluated the surface roughness of enamel following stain removal. Fluorescence spectroscopy measured spectra of unbleached and photobleached stains in the spectral range of 600-800 nm. Extrinsic enamel stains are removed with laser fluences between 0.8 and 6.4 J/cm(2) . Stains removed on sound enamel leave behind a smooth enamel surface. Stain removal in areas with signs of earlier cariogenic acid attacks resulted in isolated and randomly located laser-induced, 50-µm-diam enamel pits. These pits contain 0.5-µm diam, smooth craters indicative of heat transfer from the stain to the enamel and subsequent melting and water droplet ejection. Ablation stalling of enamel stains is typically observed at low fluences (Laser ablation of extrinsic enamel stains at 400 nm is observed to be most efficient above 3 J/cm(2) with minimal damage to the underlying enamel. Unsound underlying enamel is also observed to be selectively removed after irradiation. Copyright © 2012 Wiley Periodicals, Inc.

  18. Effect of Violet-Blue Light on Streptococcus mutans-Induced Enamel Demineralization

    Directory of Open Access Journals (Sweden)

    Grace Gomez Felix Gomez

    2018-03-01

    Full Text Available Background: This in vitro study determined the effectiveness of violet-blue light (405 nm on inhibiting Streptococcus mutans-induced enamel demineralization. Materials and Methods: S. mutans UA159 biofilm was grown on human enamel specimens for 13 h in 5% CO2 at 37 °C with/without 1% sucrose. Wet biofilm was treated twice daily with violet-blue light for five minutes over five days. A six-hour reincubation was included daily between treatments excluding the final day. Biofilms were harvested and colony forming units (CFU were quantitated. Lesion depth (L and mineral loss (∆Z were quantified using transverse microradiography (TMR. Quantitative light-induced fluorescence Biluminator (QLF-D was used to determine mean fluorescence loss. Data were analyzed using one-way analysis of variance (ANOVA to compare differences in means. Results: The results demonstrated a significant reduction in CFUs between treated and non-treated groups grown with/without 1% sucrose. ∆Z was significantly reduced for specimens exposed to biofilms grown without sucrose with violet-blue light. There was only a trend on reduction of ∆Z with sucrose and with L on both groups. There were no differences in fluorescence-derived parameters between the groups. Conclusions: Within the limitations of the study, the results indicate that violet-blue light can serve as an adjunct prophylactic treatment for reducing S. mutans biofilm formation and enamel mineral loss.

  19. Two-year Randomized Clinical Trial of Self-etching Adhesives and Selective Enamel Etching.

    Science.gov (United States)

    Pena, C E; Rodrigues, J A; Ely, C; Giannini, M; Reis, A F

    2016-01-01

    The aim of this randomized, controlled prospective clinical trial was to evaluate the clinical effectiveness of restoring noncarious cervical lesions with two self-etching adhesive systems applied with or without selective enamel etching. A one-step self-etching adhesive (Xeno V(+)) and a two-step self-etching system (Clearfil SE Bond) were used. The effectiveness of phosphoric acid selective etching of enamel margins was also evaluated. Fifty-six cavities were restored with each adhesive system and divided into two subgroups (n=28; etch and non-etch). All 112 cavities were restored with the nanohybrid composite Esthet.X HD. The clinical effectiveness of restorations was recorded in terms of retention, marginal integrity, marginal staining, caries recurrence, and postoperative sensitivity after 3, 6, 12, 18, and 24 months (modified United States Public Health Service). The Friedman test detected significant differences only after 18 months for marginal staining in the groups Clearfil SE non-etch (p=0.009) and Xeno V(+) etch (p=0.004). One restoration was lost during the trial (Xeno V(+) etch; p>0.05). Although an increase in marginal staining was recorded for groups Clearfil SE non-etch and Xeno V(+) etch, the clinical effectiveness of restorations was considered acceptable for the single-step and two-step self-etching systems with or without selective enamel etching in this 24-month clinical trial.

  20. Sub ablative Er: YAG laser irradiation on surface roughness of eroded dental enamel.

    Science.gov (United States)

    Curylofo-Zotti, Fabiana Almeida; Lepri, Taísa Penazzo; Colucci, Vivian; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

    2015-11-01

    This study evaluated the effects of Er:YAG laser irradiation applied at varying pulse repetition rate on the surface roughness of eroded enamel. Bovine enamel slabs (n = 10) were embedded in polyester resin, ground, and polished. To erosive challenges, specimens were immersed two times per day in 20mL of concentrated orange juice (pH = 3.84) under agitation, during a two-day period. Specimens were randomly assigned to irradiation with the Er:YAG laser (focused mode, pulse energy of 60 mJ and energy density of 3.79 J/cm(2) ) operating at 1, 2, 3, or 4 Hz. The control group was left nonirradiated. Surface roughness measurements were recorded post erosion-like formation and further erosive episodes by a profilometer and observed through atomic force microscopy (AFM). Analysis of variance revealed that the control group showed the lowest surface roughness, while laser-irradiated substrates did not differ from each other following post erosion-like lesion formation. According to analysis of covariance, at further erosive episodes, the control group demonstrated lower surface roughness (P > 0.05), than any of the irradiated groups (P enamel eroded. The AFM images showed that the specimens irradiated by the Er:YAG laser at 1 Hz presented a less rough surface than those irradiated at 2, 3, and 4 Hz. © 2015 Wiley Periodicals, Inc.

  1. Relationship between mineral distributions in dentine lesions and subsequent remineralization in vitro

    NARCIS (Netherlands)

    Kawasaki, K; Ruben, J; Tsuda, H; Huysmans, MCDNJM; Takagi, O

    2000-01-01

    Though the mineral distribution of the dentine carious lesion varies largely from tooth to tooth and from patient to patient, there are two main distribution profiles that characterize natural carious lesions in dentine. These profiles include softened and subsurface lesion types. The mineral

  2. Subsurface Geotechnical Parameters Report

    International Nuclear Information System (INIS)

    Rigby, D.; Mrugala, M.; Shideler, G.; Davidsavor, T.; Leem, J.; Buesch, D.; Sun, Y.; Potyondy, D.; Christianson, M.

    2003-01-01

    The Yucca Mountain Project is entering a the license application (LA) stage in its mission to develop the nation's first underground nuclear waste repository. After a number of years of gathering data related to site characterization, including activities ranging from laboratory and site investigations, to numerical modeling of processes associated with conditions to be encountered in the future repository, the Project is realigning its activities towards the License Application preparation. At the current stage, the major efforts are directed at translating the results of scientific investigations into sets of data needed to support the design, and to fulfill the licensing requirements and the repository design activities. This document addresses the program need to address specific technical questions so that an assessment can be made about the suitability and adequacy of data to license and construct a repository at the Yucca Mountain Site. In July 2002, the U.S. Nuclear Regulatory Commission (NRC) published an Integrated Issue Resolution Status Report (NRC 2002). Included in this report were the Repository Design and Thermal-Mechanical Effects (RDTME) Key Technical Issues (KTI). Geotechnical agreements were formulated to resolve a number of KTI subissues, in particular, RDTME KTIs 3.04, 3.05, 3.07, and 3.19 relate to the physical, thermal and mechanical properties of the host rock (NRC 2002, pp. 2.1.1-28, 2.1.7-10 to 2.1.7-21, A-17, A-18, and A-20). The purpose of the Subsurface Geotechnical Parameters Report is to present an accounting of current geotechnical information that will help resolve KTI subissues and some other project needs. The report analyzes and summarizes available qualified geotechnical data. It evaluates the sufficiency and quality of existing data to support engineering design and performance assessment. In addition, the corroborative data obtained from tests performed by a number of research organizations is presented to reinforce

  3. Subsurface Geotechnical Parameters Report

    Energy Technology Data Exchange (ETDEWEB)

    D. Rigby; M. Mrugala; G. Shideler; T. Davidsavor; J. Leem; D. Buesch; Y. Sun; D. Potyondy; M. Christianson

    2003-12-17

    The Yucca Mountain Project is entering a the license application (LA) stage in its mission to develop the nation's first underground nuclear waste repository. After a number of years of gathering data related to site characterization, including activities ranging from laboratory and site investigations, to numerical modeling of processes associated with conditions to be encountered in the future repository, the Project is realigning its activities towards the License Application preparation. At the current stage, the major efforts are directed at translating the results of scientific investigations into sets of data needed to support the design, and to fulfill the licensing requirements and the repository design activities. This document addresses the program need to address specific technical questions so that an assessment can be made about the suitability and adequacy of data to license and construct a repository at the Yucca Mountain Site. In July 2002, the U.S. Nuclear Regulatory Commission (NRC) published an Integrated Issue Resolution Status Report (NRC 2002). Included in this report were the Repository Design and Thermal-Mechanical Effects (RDTME) Key Technical Issues (KTI). Geotechnical agreements were formulated to resolve a number of KTI subissues, in particular, RDTME KTIs 3.04, 3.05, 3.07, and 3.19 relate to the physical, thermal and mechanical properties of the host rock (NRC 2002, pp. 2.1.1-28, 2.1.7-10 to 2.1.7-21, A-17, A-18, and A-20). The purpose of the Subsurface Geotechnical Parameters Report is to present an accounting of current geotechnical information that will help resolve KTI subissues and some other project needs. The report analyzes and summarizes available qualified geotechnical data. It evaluates the sufficiency and quality of existing data to support engineering design and performance assessment. In addition, the corroborative data obtained from tests performed by a number of research organizations is presented to reinforce

  4. Clinical and radiographic assessment of approximal carious lesions

    International Nuclear Information System (INIS)

    Espelid, I.; Tveit, A.B.

    1986-01-01

    The aim of the study was to compare the radiographic diagnosis of approximal carious lesions with visual observations of the approximal surfaces and within drilled Class II cavities (made into the pulp). Sound (n=28) and carious (n=123) approximal surfaces of extracted premolars and molars were radiographed. The radiographs were studied by seven observers to diagnose caries. Lesions without cavitation were most often classified as sound (61.3%). When lesions had cavities, the rate of detection increased to 89.1%. Sound surfaces were erroneously classified as carious in 15.7% of cases. Statistically, about 6 our of every 10 qualitative assessments of lesion depth on the basis of radiographs, correctly recorded lesions as being in enamel or extending into dentin. The interexaminer variation in radiographic caries diagnosis were mostly due to difference in diagnostic criteria, whereas differences in diagnostic capability were less important

  5. Fluoride releasing and enamel demineralization around orthodontic brackets by fluoride-releasing composite containing nanoparticles.

    Science.gov (United States)

    Melo, Mary A S; Morais, Weslanny A; Passos, Vanara F; Lima, Juliana P M; Rodrigues, Lidiany K A

    2014-05-01

    Fluoride-containing materials have been suggested to control enamel demineralization around orthodontic brackets during the treatment with fixed appliances. The improvement of their properties has been made through innovations, such as the application of nanotechnology by incorporation of nanofillers. This in vitro study evaluated the capacity of fluoride releasing and enamel demineralization inhibition of fluoride-releasing nanofilled cement around orthodontic brackets using an artificial caries biofilm model. Forty bovine enamel discs were selected by evaluating surface microhardness and randomized into four groups (n = 10): non-fluoride-releasing microfilled composite, fluoride-releasing microfilled composite, resin-modified glass ionomer cement (RMGI), and fluoride-releasing nanofilled composite (FN). After brackets bonding in each disc, the specimens were subjected to a cariogenic challenge through a Streptococcus mutans biofilm model. After the experimental period, the biofilm formed around the brackets was collected for fluoride analysis and the mineral loss around the brackets was determined by integrated demineralization via cross-sectional microhardness measurement at 20 and 70 μm from the bracket margin. Additionally, samples of each group were subjected to energy-dispersive X-ray spectroscopy (EDX) analysis examined under a scanning electron microscopy (SEM). ANOVA followed by Tukey test were applied for fluoride concentration and mineral loss data, respectively. At both distances, only RMGI statistically differed from the other groups presenting the lowest demineralization, although there was a trend to a lower demineralization of enamel around brackets in FN group. Similar condition was found to fluoride concentration and EDX/SEM analysis. Under the cariogenic exposure condition of this study, the fluoride-releasing nanofilled material had similar performance to fluoride-releasing microfilled materials. The presence of nanofillers in the fluoride

  6. Effect of beverages on bovine dental enamel subjected to erosive challenge with hydrochloric acid.

    Science.gov (United States)

    Amoras, Dinah Ribeiro; Corona, Silmara Aparecida Milori; Rodrigues, Antonio Luiz; Serra, Mônica Campos

    2012-01-01

    This study evaluated by an in vitro model the effect of beverages on dental enamel previously subjected to erosive challenge with hydrochloric acid. The factor under study was the type of beverage, in five levels: Sprite® Zero Low-calorie Soda Lime (positive control), Parmalat® ultra high temperature (UHT) milk, Ades® Original soymilk, Leão® Ice Tea Zero ready-to-drink low-calorie peach-flavored black teaand Prata® natural mineral water (negative control). Seventy-five bovine enamel specimens were distributed among the five types of beverages (n=15), according to a randomized complete block design. For the formation of erosive wear lesions, the specimens were immersed in 10 mL aqueous solution of hydrochloric acid 0.01 M for 2 min. Subsequently, the specimens were immersed in 20 mL of the beverages for 1 min, twice daily for 2 days at room temperature. In between, the specimens were kept in 20 mL of artificial saliva at 37ºC. The response variable was the quantitative enamel microhardness. ANOVA and Tukey's test showed highly significant differences (penamel exposed to hydrochloric acid and beverages. The soft drink caused a significantly higher decrease in microhardness compared with the other beverages. The black tea caused a significantly higher reduction in microhardness than the mineral water, UHT milk and soymilk, but lower than the soft drink. Among the analyzed beverages, the soft drink and the black tea caused the most deleterious effects on dental enamel microhardness.

  7. Quantitative analysis of fluoride-induced hypermineralization of developing enamel in neonatal hamster tooth germs

    Science.gov (United States)

    Tros, G. H. J.; Lyaruu, D. M.; Vis, R. D.

    1993-10-01

    A procedure was developed for analysing the effect of fluoride on mineralization in the enamel of neonatal hamster molars during amelogenesis by means of the quantitative determination of the mineral content. In this procedure the distribution of calcium and mineral concentration was determined in sections containing developing tooth enamel mineral embedded in an organic epoxy resin matrix by means of the micro-PIXE technique. This allowed the determination of the calcium content along preselected tracks with a spatial resolution of 2 μm using a microprobe PIXE setup with a 3 MeV proton beam of 10 to 50 pA with a spot size of 2 μm in the track direction. In this procedure the X-ray yield is used as a measure for the calcium content. The thickness of each sample section is determined independently by measuring the energy loss of α-particles from a calibration source upon passing through the sample. The sample is considered as consisting of two bulk materials, allowing the correction for X-ray self-absorption and the calculation of the calcium concentration. The procedure was applied for measuring the distribution of mineral concentration in 2 μm thick sections taken from tooth germs of hamsters administered with NaF. The measurements indicated that a single intraperitoneal administration of 20 mg NaF/kg body weight to 4-to-5-day-old hamsters leads within 24 h to hypermineralization of certain focal enamel surface areas containing cystic lesions under transitional and early secretory ameloblasts. The mineral concentration there is substantially increased due to the fluoride treatment (35%, instead of 5 to 10% as in the controls), indicating that the normal mineralization process has been seriously disturbed. Furthermore it is found that using this technique the mineral concentration peaks at about 70% at the dentine-enamel junction, which is comparable to that reported for human dentine using other techniques.

  8. Proteomic Mapping of Dental Enamel Matrix from Inbred Mouse Strains: Unraveling Potential New Players in Enamel.

    Science.gov (United States)

    Lima Leite, Aline; Silva Fernandes, Mileni; Charone, Senda; Whitford, Gary Milton; Everett, Eric T; Buzalaf, Marília Afonso Rabelo

    2018-01-01

    Enamel formation is a complex 2-step process by which proteins are secreted to form an extracellular matrix, followed by massive protein degradation and subsequent mineralization. Excessive systemic exposure to fluoride can disrupt this process and lead to a condition known as dental fluorosis. The genetic background influences the responses of mineralized tissues to fluoride, such as dental fluorosis, observed in A/J and 129P3/J mice. The aim of the present study was to map the protein profile of enamel matrix from A/J and 129P3/J strains. Enamel matrix samples were obtained from A/J and 129P3/J mice and analyzed by 2-dimensional electrophoresis and liquid chromatography coupled with mass spectrometry. A total of 120 proteins were identified, and 7 of them were classified as putative uncharacterized proteins and analyzed in silico for structural and functional characterization. An interesting finding was the possibility of the uncharacterized sequence Q8BIS2 being an enzyme involved in the degradation of matrix proteins. Thus, the results provide a comprehensive view of the structure and function for putative uncharacterized proteins found in the enamel matrix that could help to elucidate the mechanisms involved in enamel biomineralization and genetic susceptibility to dental fluorosis. © 2018 S. Karger AG, Basel.

  9. SUBSURFACE CONSTRUCTION AND DEVELOPMENT ANALYSIS

    International Nuclear Information System (INIS)

    N.E. Kramer

    1998-01-01

    The purpose of this analysis is to identify appropriate construction methods and develop a feasible approach for construction and development of the repository subsurface facilities. The objective of this analysis is to support development of the subsurface repository layout for License Application (LA) design. The scope of the analysis for construction and development of the subsurface Repository facilities covers: (1) Excavation methods, including application of knowledge gained from construction of the Exploratory Studies Facility (ESF). (2) Muck removal from excavation headings to the surface. This task will examine ways of preventing interference with other subsurface construction activities. (3) The logistics and equipment for the construction and development rail haulage systems. (4) Impact of ground support installation on excavation and other construction activities. (5) Examination of how drift mapping will be accomplished. (6) Men and materials handling. (7) Installation and removal of construction utilities and ventilation systems. (8) Equipping and finishing of the emplacement drift mains and access ramps to fulfill waste emplacement operational needs. (9) Emplacement drift and access mains and ramps commissioning prior to handover for emplacement operations. (10) Examination of ways to structure the contracts for construction of the repository. (11) Discussion of different construction schemes and how to minimize the schedule risks implicit in those schemes. (12) Surface facilities needed for subsurface construction activities

  10. Program overview: Subsurface science program

    International Nuclear Information System (INIS)

    1994-03-01

    The OHER Subsurface Science Program is DOE's core basic research program concerned with subsoils and groundwater. These practices have resulted in contamination by mixtures of organic chemicals, inorganic chemicals, and radionuclides. A primary long-term goal is to provide a foundation of knowledge that will lead to the reduction of environmental risks and to cost-effective cleanup strategies. Since the Program was initiated in 1985, a substantial amount of research in hydrogeology, subsurface microbiology, and the geochemistry of organically complexed radionuclides has been completed, leading to a better understanding of contaminant transport in groundwater and to new insights into microbial distribution and function in the subsurface environments. The Subsurface Science Program focuses on achieving long-term scientific advances that will assist DOE in the following key areas: providing the scientific basis for innovative in situ remediation technologies that are based on a concept of decontamination through benign manipulation of natural systems; understanding the complex mechanisms and process interactions that occur in the subsurface; determining the influence of chemical and geochemical-microbial processes on co-contaminant mobility to reduce environmental risks; improving predictions of contaminant transport that draw on fundamental knowledge of contaminant behavior in the presence of physical and chemical heterogeneities to improve cleanup effectiveness and to predict environmental risks

  11. Theobromine Effects on Enamel Surface Microhardness: In Vitro

    OpenAIRE

    Grace Syafira; Rina Permatasari; Nina Wardani

    2013-01-01

    Dental caries is still a dental health problem in Indonesia. Fluoride, one of the dental caries prevention material, but its safety and the danger of fluorosis is still debated. Theobromine is an alkaloid compound contained in cocoa beans. Theobromine is believed to increase enamel microhardness with mineral changes in the enamel superficial layer. Objectives: To determine the influence of theobromine on the enamel surface microhardness. Methods: This study used 40 premolar tooth crown pieces...

  12. Enamelin is critical for ameloblast integrity and enamel ultrastructure formation.

    Directory of Open Access Journals (Sweden)

    Jan C-C Hu

    Full Text Available Mutations in the human enamelin gene cause autosomal dominant hypoplastic amelogenesis imperfecta in which the affected enamel is thin or absent. Study of enamelin knockout NLS-lacZ knockin mice revealed that mineralization along the distal membrane of ameloblast is deficient, resulting in no true enamel formation. To determine the function of enamelin during enamel formation, we characterized the developing teeth of the Enam-/- mice, generated amelogenin-driven enamelin transgenic mouse models, and then introduced enamelin transgenes into the Enam-/- mice to rescue enamel defects. Mice at specific stages of development were subjected to morphologic and structural analysis using β-galactosidase staining, immunohistochemistry, and transmission and scanning electron microscopy. Enamelin expression was ameloblast-specific. In the absence of enamelin, ameloblasts pathology became evident at the onset of the secretory stage. Although the aggregated ameloblasts generated matrix-containing amelogenin, they were not able to create a well-defined enamel space or produce normal enamel crystals. When enamelin is present at half of the normal quantity, enamel was thinner with enamel rods not as tightly arranged as in wild type suggesting that a specific quantity of enamelin is critical for normal enamel formation. Enamelin dosage effect was further demonstrated in transgenic mouse lines over expressing enamelin. Introducing enamelin transgene at various expression levels into the Enam-/- background did not fully recover enamel formation while a medium expresser in the Enam+/- background did. Too much or too little enamelin abolishes the production of enamel crystals and prism structure. Enamelin is essential for ameloblast integrity and enamel formation.

  13. Enamelin Is Critical for Ameloblast Integrity and Enamel Ultrastructure Formation

    Science.gov (United States)

    Hu, Jan C.-C.; Hu, Yuanyuan; Lu, Yuhe; Smith, Charles E.; Lertlam, Rangsiyakorn; Wright, John Timothy; Suggs, Cynthia; McKee, Marc D.; Beniash, Elia; Kabir, M. Enamul; Simmer, James P.

    2014-01-01

    Mutations in the human enamelin gene cause autosomal dominant hypoplastic amelogenesis imperfecta in which the affected enamel is thin or absent. Study of enamelin knockout NLS-lacZ knockin mice revealed that mineralization along the distal membrane of ameloblast is deficient, resulting in no true enamel formation. To determine the function of enamelin during enamel formation, we characterized the developing teeth of the Enam−/− mice, generated amelogenin-driven enamelin transgenic mouse models, and then introduced enamelin transgenes into the Enam−/− mice to rescue enamel defects. Mice at specific stages of development were subjected to morphologic and structural analysis using β-galactosidase staining, immunohistochemistry, and transmission and scanning electron microscopy. Enamelin expression was ameloblast-specific. In the absence of enamelin, ameloblasts pathology became evident at the onset of the secretory stage. Although the aggregated ameloblasts generated matrix-containing amelogenin, they were not able to create a well-defined enamel space or produce normal enamel crystals. When enamelin is present at half of the normal quantity, enamel was thinner with enamel rods not as tightly arranged as in wild type suggesting that a specific quantity of enamelin is critical for normal enamel formation. Enamelin dosage effect was further demonstrated in transgenic mouse lines over expressing enamelin. Introducing enamelin transgene at various expression levels into the Enam−/− background did not fully recover enamel formation while a medium expresser in the Enam+/− background did. Too much or too little enamelin abolishes the production of enamel crystals and prism structure. Enamelin is essential for ameloblast integrity and enamel formation. PMID:24603688

  14. Indentation Damage and Crack Repair in Human Enamel*

    OpenAIRE

    Rivera, C.; Arola, D.; Ossa, A.

    2013-01-01

    Tooth enamel is the hardest and most highly mineralized tissue in the human body. While there have been a number of studies aimed at understanding the hardness and crack growth resistance behavior of this tissue, no study has evaluated if cracks in this tissue undergo repair. In this investigation the crack repair characteristics of young human enamel were evaluated as a function of patient gender and as a function of the distance from the Dentin Enamel Junction (DEJ). Cracks were introduced ...

  15. Effect of light-curable fluoride varnish on enamel demineralization adjacent to orthodontic brackets: an in-vivo study.

    Science.gov (United States)

    Mehta, Anurag; Paramshivam, Ganesh; Chugh, Vinay Kumar; Singh, Surjit; Halkai, Sudha; Kumar, Santosh

    2015-11-01

    The purpose of this in-vivo study was to evaluate the effect of a single application of Clinpro XT (3M ESPE, Pymble, New South Wales, Australia), a light-curable fluoride varnish, on enamel demineralization adjacent to orthodontic brackets. Thirty-eight patients (152 teeth) whose orthodontic treatment involved extraction of 4 first premolars were recruited. Two premolars each were assigned to the control group (no treatment) and the experimental group (received fluoride varnish application). The study was designed as a nonrandomized split-mouth study in which diagonally opposite quadrants received the same treatment. After the bonding procedures, a sectional T-loop was ligated into each bracket to serve as a site for plaque retention for enhanced demineralization. Clinpro XT was applied on the buccal surfaces adjacent to the brackets on all teeth in the experimental group only. Teeth in both groups were extracted after 15 days (n = 30), 30 days (n = 30), 45 days (n = 30), 90 days (n = 18), and 120 days (n = 18). Buccolingual sections were then evaluated under polarized light microscopy. After we excluded the dropouts, the mean depth of the demineralized enamel lesions was measured in final sample of 126 teeth. The Mann-Whitney test was used for comparison of the groups. In the control group, the depths of the demineralized enamel lesions increased from 30 to 120 days, whereas in the experimental group no sign of demineralization was noted throughout the observation period except for 3 teeth. Significant differences in the depths of demineralized lesions were found between the study groups. Clinpro XT light-curable fluoride varnish may be a reasonable alternative in the reduction of enamel demineralization around orthodontic brackets, especially in noncompliant and high-risk patients. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  16. Quantification of white spot lesions around orthodontic brackets with image analysis.

    NARCIS (Netherlands)

    Livas, C.; Kuijpers-Jagtman, A.M.; Bronkhorst, E.M.; Derks, A.; Katsaros, C.

    2008-01-01

    OBJECTIVE: To investigate the use of image analysis for diagnosis and quantification of artificial white spot lesions on digital photographs before and after removal of orthodontic brackets. MATERIALS AND METHODS: Enamel demineralization was artificially induced on the labial surface of 20 teeth

  17. Special Frits for Direct-On Enamelling of Pipelines

    International Nuclear Information System (INIS)

    Berdzenishvili, I.; Siradze, M.; Erokhin, V.; Kldiashvili, R.

    2010-01-01

    The compositions of low-melting zirconium-strontium frits have been developed for direct-on enamelling of pipes. Owing to the given combination of active cations, toxic fluorine and expensive nickel and lithium were eliminated from glass frit compositions. The enamels were subjected to firing by the induction method. In the synthesized enamels, the optimal complex of properties combining high corrosion-resistant and thermo-mechanic indices, adhesive strength and required specifications was realized. These enamels are recommended for testing on pipelines. (author)

  18. Tooth enamel sample preparation using alkaline treatment in ESR dosimetry

    International Nuclear Information System (INIS)

    Yongzeng, Zhou; Jiadong, Wang; Xiaomei, Jia; Ke, Wu; Jianbo, Cong

    2002-01-01

    Tooth enamel sample preparation using alkaline treatment was studied and compared with traditional mechanical method in this paper. 20 adult teeth were used. Samples were placed into NaOH solution. This method requires 4-5 weeks and the enamel was separated from dentin. Experimental results show that 8M NaOH was appropriate for separating enamel from dentin and that there is no difference in background signal relative intensity between samples prepared by mechanical and by chemical methods. There is also no difference in radiosensitivity between samples prepared by two methods mentioned above. Dose response curve for tooth enamel samples isolated by 8M NaOH solution was obtained

  19. Fluoride uptake from restorative dental materials by human enamel

    International Nuclear Information System (INIS)

    Forsten, L.; Rytoemaa, I.; Anttila, A.; Keinonen, J.

    1976-01-01

    The purpose of the study was to determine the uptake in vitro of fluoride from restorative materials by tooth enamel and whether prior etching of the enamel causes a change of uptake. The outermost layer of the labial surface of extracted canines was removed by grinding and the enamel was covered with five different fluoride-containing materials ; a silicate, a composite resin, an amalgam, a silicophosphate, and a polycarboxylate luting cement. The material was either removed immediately or after storing the tooth in distilled water. The fluoride content was determined using a sensitive physical method based on the 19 F (p, αγ) 16 O reaction. In addition, the fluoride content of enamel after etching for different periods of time and of etched enamel which had been in contact with silicate cement was determined. The mean fluoride content of uncovered interior enamel was 226 parts 10 6 . All materials, except the composite, increased clearly the fluoride content of the underlying enamel. Etching of interior enamel also increased the fluoride values. No difference could be shown in fluoride uptake from silicate and composite resin between etched and unetched enamel. (author)

  20. On the R-curve behavior of human tooth enamel.

    Science.gov (United States)

    Bajaj, Devendra; Arola, Dwayne D

    2009-08-01

    In this study the crack growth resistance behavior and fracture toughness of human tooth enamel were quantified using incremental crack growth measures and conventional fracture mechanics. Results showed that enamel undergoes an increase in crack growth resistance (i.e. rising R-curve) with crack extension from the outer to the inner enamel, and that the rise in toughness is a function of distance from the dentin enamel junction (DEJ). The outer enamel exhibited the lowest apparent toughness (0.67+/-0.12 MPam(0.5)), and the inner enamel exhibited a rise in the growth toughness from 1.13 MPam(0.5)/mm to 3.93 MPam(0.5)/mm. The maximum crack growth resistance at fracture (i.e. fracture toughness (K(c))) ranged from 1.79 to 2.37 MPam(0.5). Crack growth in the inner enamel was accompanied by a host of mechanisms operating from the micro- to the nano-scale. Decussation in the inner enamel promoted crack deflection and twist, resulting in a reduction of the local stress intensity at the crack tip. In addition, extrinsic mechanisms such as bridging by unbroken ligaments of the tissue and the organic matrix promoted crack closure. Microcracking due to loosening of prisms was also identified as an active source of energy dissipation. In summary, the unique microstructure of enamel in the decussated region promotes crack growth toughness that is approximately three times that of dentin and over ten times that of bone.

  1. Mineral composition of enamel from two South African population groups

    Energy Technology Data Exchange (ETDEWEB)

    Retief, D H [University of the Witwatersrand, Johannesburg (South Africa). Dental Research Unit; Turkstra, J [University of Fort Hare, Alice (South Africa). Department of Chemistry; Cleaton-Jones, P E; Biddlecombe, F [Atomic Energy Board, Pelindaba, Pretoria (South Africa). Chemistry Div.

    1979-10-01

    The mineral composition of pooled bulk enamel from Black and White South Africans respectively, resident in the Johannesburg area, was determined by neutron activation analysis and high resolution gamma spectromety. The differences between the concentrations of Ca, Cl, Mg, Na, Br and Co in the enamel of the two population groups were apparently not significant. There was a trend for the concentrations of Al, Ag, Au, Fe, Sb, and Zn to be higher in the enamel from the White subjects and for the concentrations of Mn, Se and Sr to be higher in the enamel from the Black subjects.

  2. Enamel alteration following tooth bleaching and remineralization

    OpenAIRE

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

    2015-01-01

    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.\\ud \\ud 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 ...

  3. Microtensile bond strength of enamel after bleaching

    Directory of Open Access Journals (Sweden)

    Andréa Dias Neves Lago

    2013-01-01

    Full Text Available Objective: To evaluate the bond strength of a composite resin to the bovine enamel bleached with 35% hydrogen peroxide. It was used an etching-and-rinse adhesive system employed immediately, 7 and 14 days after the bleaching. Materials and Methods: Twenty bovine teeth were randomly distributed into 4 groups (n = 5, 3 experimental and 1 control. G1: Unbleached + restoration 14 days after storage in artificial saliva (control; G2: Bleached + restoration immediately after bleaching; G3: Bleached + restoration 7 days after bleaching; G4: Bleached + restoration 14 days after bleaching. Their buccal enamel surfaces were flattened, and a 25 mm² (5 × 5 mm area from each one of these regions was outlined so as to standardize the experimental region. Universal hybrid composite resin Filtek™Z350 was inserted into four layers of 1 mm each and photo-activated. The bond strength was quantitatively evaluated by a microtensile test (1.0 mm/min 24 h after the restorative procedures. The failure mode was assessed through scanning electron microscopy (SEM. Results: There was a significant reduction in the bond strength of the restored teeth immediately after the bleaching (G2. There were no significant differences in enamel bond strength between groups G1, G3, and G4. There was a predominance of adhesive and mixed (cohesive + adhesive failure in all groups. Conclusion: The 7-day-period after the end of the bleaching with 35% hydrogen peroxide was enough to achieve the appropriate values of bond strength to the enamel.

  4. Subsurface microbial habitats on Mars

    Science.gov (United States)

    Boston, P. J.; Mckay, C. P.

    1991-01-01

    We developed scenarios for shallow and deep subsurface cryptic niches for microbial life on Mars. Such habitats could have considerably prolonged the persistence of life on Mars as surface conditions became increasingly inhospitable. The scenarios rely on geothermal hot spots existing below the near or deep subsurface of Mars. Recent advances in the comparatively new field of deep subsurface microbiology have revealed previously unsuspected rich aerobic and anaerobic microbal communities far below the surface of the Earth. Such habitats, protected from the grim surface conditions on Mars, could receive warmth from below and maintain water in its liquid state. In addition, geothermally or volcanically reduced gases percolating from below through a microbiologically active zone could provide the reducing power needed for a closed or semi-closed microbial ecosystem to thrive.

  5. Investigation of EPR signals on tooth enamel

    Energy Technology Data Exchange (ETDEWEB)

    Pavlenko, A; Mironova-Ulmane, N; Polakov, M; Riekstina, D [Institute of Solid State Physics, University of Latvia, Riga (Latvia)

    2007-12-15

    Calcified tissues are involved in continues metabolic process in human organism exchanging a number of chemical elements with environment. The rate of biochemical reactions is tissue dependent and the slowest one at the tooth enamel, the most mineralized tissue of human organism. The long time stability and unique chemical composition make tooth enamel suitable for number of application. The assessment of individual radiation dose by Electron Paramagnetic Resonance (EPR) and evaluations of elemental composition by Instrumentation Neutron Activation Analysis (INAA) are the well known procedures where properties of tooth enamel intensively used. The current work is focused on investigation of EPR signals and determination of chemical composition on several teeth samples having different origin. The EPR spectra and INAA element content of milk tooth, caries tooth, and paradantose tooth have been compared to each other. The results showed that the intensity of EPR signal is much higher for the caries tooth than the for paradantose tooth that is in agreement with depleted Ca content.

  6. A comparative study on component volumes from outer to inner dental enamel in relation to enamel tufts.

    Science.gov (United States)

    Setally Azevedo Macena, Marcus; de Alencar e Silva Leite, Maria Luísa; de Lima Gouveia, Cíntia; de Lima, Tamires Alcoforado Sena; Athayde, Priscilla Alves Aguiar; de Sousa, Frederico Barbosa

    2014-06-01

    Dental enamel presents marked mechanical properties gradients from outer to inner enamel, a region lacking component volumes profiles. Tufts, structures of inner enamel, have been shown to play a role in enamel resilience. We aimed at comparing component volumes from inner to outer enamel in relation to enamel tufts. Transversal ground sections from the cervical half of unerupted human third molars (n=10) were prepared and histological points were selected along transversal lines (extending from innermost to outer enamel) traced across tufts and adjacent control areas without tufts. Component volumes were measured at each histological point. Component volumes ranges were: 70.6-98.5% (mineral), 0.02-20.78% (organic), 3.8-9.8% (total water), 3-9% (firmly bound water), and 0.02-3.3% (loosely bound water). Inner enamel presented the lowest mineral volumes and the highest non-mineral volumes. Mineral, water and organic contents differed as a function of the distance from innermost enamel but not between the tuft and control lines. Tufts presented opaqueness in polarizing microscopy (feature of fracture lines). Organic volume gradient correlated with a relatively flat profile of loosely bound water. Inner, but not outer enamel, rehydrated after air-dried enamel was heated to 50°C and re-exposed to room conditions, as predicted by the organic/water gradient profiles. Component volumes vary markedly from outer to inner enamel, but not between areas with or without tufts (that behave like fracture lines under polarizing microscopy). Copyright © 2014 Elsevier Ltd. All rights reserved.

  7. Subsurface Fire Hazards Technical Report

    International Nuclear Information System (INIS)

    Logan, R.C.

    1999-01-01

    The results from this report are preliminary and cannot be used as input into documents supporting procurement, fabrication, or construction. This technical report identifies fire hazards and proposes their mitigation for the subsurface repository fire protection system. The proposed mitigation establishes the minimum level of fire protection to meet NRC regulations, DOE fire protection orders, that ensure fire containment, adequate life safety provisions, and minimize property loss. Equipment requiring automatic fire suppression systems is identified. The subsurface fire hazards that are identified can be adequately mitigated

  8. Treatment of a Periodontic-Endodontic Lesion in a Patient with Aggressive Periodontitis

    OpenAIRE

    Fahmy, Mina D.; Luepke, Paul G.; Ibrahim, Mohamed S.; Guentsch, Arndt

    2016-01-01

    Case Description. This case report describes the successful management of a left mandibular first molar with a combined periodontic-endodontic lesion in a 35-year-old Caucasian woman with aggressive periodontitis using a concerted approach including endodontic treatment, periodontal therapy, and a periodontal regenerative procedure using an enamel matrix derivate. In spite of anticipated poor prognosis, the tooth lesion healed. This case report also discusses the rationale behind different tr...

  9. Effect of Surface Treatment on Enamel Cracks After Orthodontic Bracket Debonding: Er,Cr:YSGG Laser-Etching Versus Acid-Etching

    Science.gov (United States)

    Ghaffari, Hassanali; Mirhashemi, Amirhossein; Baherimoghadam, Tahereh; Azmi, Amir

    2017-01-01

    Objectives: This study sought to compare enamel cracks after orthodontic bracket debonding in the surfaces prepared with erbium, chromium: yttrium-scandium-galliumgarnet (Er,Cr:YSGG) laser and the conventional acid-etching technique. Materials and Methods: This in-vitro experimental study was conducted on 60 sound human premolars extracted for orthodontic purposes. The teeth were randomly divided into two groups (n=30). The teeth in group A were etched with 37% phosphoric acid gel, while the teeth in group B were subjected to Er,Cr:YSGG laser irradiation (gold handpiece, MZ8 tip, 50Hz, 4.5W, 60μs, 80% water and 60% air). Orthodontic brackets were bonded to the enamel surfaces and were then debonded in both groups. The samples were inspected under a stereomicroscope at ×38 magnification to assess the number and length of enamel cracks before bonding and after debonding. Independent-samples t-test was used to compare the frequency of enamel cracks in the two groups. Levene’s test was applied to assess the equality of variances. Results: No significant difference was noted in the frequency or length of enamel cracks between the two groups after debonding (P>0.05). Conclusions: Despite the same results of the frequency and length of enamel cracks in the two groups and by considering the side effects of acid-etching (demineralization and formation of white spot lesions), Er,Cr:YSGG laser may be used as an alternative to acid-etching for enamel surface preparation prior to bracket bonding. PMID:29296111

  10. Targeted p120-catenin ablation disrupts dental enamel development.

    Science.gov (United States)

    Bartlett, John D; Dobeck, Justine M; Tye, Coralee E; Perez-Moreno, Mirna; Stokes, Nicole; Reynolds, Albert B; Fuchs, Elaine; Skobe, Ziedonis

    2010-09-16

    Dental enamel development occurs in stages. The ameloblast cell layer is adjacent to, and is responsible for, enamel formation. When rodent pre-ameloblasts become tall columnar secretory-stage ameloblasts, they secrete enamel matrix proteins, and the ameloblasts start moving in rows that slide by one another. This movement is necessary to form the characteristic decussating enamel prism pattern. Thus, a dynamic system of intercellular interactions is required for proper enamel development. Cadherins are components of the adherens junction (AJ), and they span the cell membrane to mediate attachment to adjacent cells. p120 stabilizes cadherins by preventing their internalization and degradation. So, we asked if p120-mediated cadherin stability is important for dental enamel formation. Targeted p120 ablation in the mouse enamel organ had a striking effect. Secretory stage ameloblasts detached from surrounding tissues, lost polarity, flattened, and ameloblast E- and N-cadherin expression became undetectable by immunostaining. The enamel itself was poorly mineralized and appeared to be composed of a thin layer of merged spheres that abraded from the tooth. Significantly, p120 mosaic mouse teeth were capable of forming normal enamel demonstrating that the enamel defects were not a secondary effect of p120 ablation. Surprisingly, blood-filled sinusoids developed in random locations around the developing teeth. This has not been observed in other p120-ablated tissues and may be due to altered p120-mediated cell signaling. These data reveal a critical role for p120 in tooth and dental enamel development and are consistent with p120 directing the attachment and detachment of the secretory stage ameloblasts as they move in rows.

  11. The efficiency of child formula dentifrices containing different calcium and phosphate compounds on artificial enamel caries.

    Science.gov (United States)

    Rirattanapong, Praphasri; Vongsavan, Kadkao; Saengsirinavin, Chavengkiat; Khumsub, Ploychompoo

    2016-01-01

    Fluoride toothpaste has been extensively used to prevent dental caries. However, the risk of fluorosis is concerning, especially in young children. Calcium phosphate has been an effective remineralizing agent and is present in commercial dental products, with no risk of fluorosis to users. This in vitro study aimed to compare the effects of different calcium phosphate compounds and fluoride-containing dentifrices on artificial caries in primary teeth. Fifty sound primary incisors were coated with nail varnish, leaving two 1 mm 2 windows on the labial surface before immersion in demineralizing solution for 96 hours to produce artificial enamel lesions. Subsequently, one window from each tooth was coated with nail varnish, and all 50 teeth were divided into five groups ( n = 10); group A - deionized water; group B - casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste (Tooth Mousse); group C - 500 ppm F (Colgate Spiderman ® ); group D - nonfluoridated toothpaste with triple calcium phosphate (Pureen ® ); and group E - tricalcium phosphate (TCP). Polarized light microscopy and Image-Pro ® Plus software were used to evaluate lesions. After a 7-day pH-cycle, mean lesion depths in groups A, B, C, D, and E had increased by 57.52 ± 10.66%, 33.28 ± 10.16%, 17.04 ± 4.76%, 32.51 ± 8.99%, and 21.76 ± 8.15%, respectively. All data were processed by the Statistical Package for the Social Sciences (version 16.0) software package. Comparison of percentage changes using one-way analysis of variance and Fisher's least squares difference tests at a 95% level of confidence demonstrated that group A was significantly different from the other groups ( P < 0.001). Lesions in groups B and D had a significant lesion progression when compared with groups C and E. All toothpastes in this study had the potential to delay the demineralization progression of artificial enamel caries in primary teeth. The fluoride 500 ppm and TCP toothpastes were equal in the deceleration of

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

    Science.gov (United States)

    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. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Feasibility of a subsurface storage

    International Nuclear Information System (INIS)

    1998-11-01

    This report analyses the notion of subsurface storage under the scientifical, technical and legal aspects. This reflection belongs to the studies about long duration storage carried out in the framework of the axis 3 of the December 30, 1991 law. The report comprises 3 parts. The first part is a synthesis of the complete subsurface storage study: definitions, aim of the report, very long duration storage paradigm, description files of concepts, thematic synthesis (legal aspects, safety, monitoring, sites, seismicity, heat transfers, corrosion, concretes, R and works, handling, tailings and dismantlement, economy..), multi-criteria/multi-concept cross-analysis. The second part deals with the technical aspects of the subsurface storage: safety approach (long duration impact, radiation protection, mastery of effluents), monitoring strategy, macroscopic inventory of B-type waste packages, inventory of spent fuels, glasses, hulls and nozzles, geological contexts in the French territory (sites selection and characterization), on-site activities, hydrogeological and geochemical aspects, geo-technical works and infrastructures organization, subsurface seismic effects, cooling modes (ventilation, heat transfer with the geologic environment), heat transfer research programs (convection, poly-phase cooling in porous media), handling constraints, concretes (use, behaviour, durability), corrosion of metallic materials, technical-economical analysis, international context (experience feedback from Sweden (CLAB) and the USA (Yucca Mountain), other European and French facilities). The last part of the report is a graphical appendix with 3-D views and schemes of the different concepts. (J.S.)

  14. Safety analysis in subsurface repositories

    International Nuclear Information System (INIS)

    1985-06-01

    The development of mathematical models to represent the repository-geosphere-biosphere system, and the development of a structure for data acquisition, processing, and use to analyse the safety of subsurface repositories, are presented. To study the behavior of radionuclides in geosphere a laboratory to determine the hydrodynamic dispersion coefficient was constructed. (M.C.K.) [pt

  15. The increasing of enamel calcium level after casein phosphopeptideamorphous calcium phosphate covering

    Directory of Open Access Journals (Sweden)

    Widyasri Prananingrum

    2012-06-01

    Full Text Available Background: Caries process is characterized by the presence of demineralization. Demineralization is caused by organic acids as a result of carbohydrate substrate fermentation. Remineralization is a natural repair process for non-cavitated lesions. Remineralization occurs if there are Ca2+ and PO43- ions in sufficient quantities. Casein-amorphous calcium phosphate phosphopeptide (CPP-ACP is a paste material containing milk protein (casein, that actually contains minerals, such as calcium and phosphate. The casein ability to stabilize calcium phosphate and enhance mineral solubility and bioavailability confers upon CPP potential to be biological delivery vehicles for calcium and phosphate. Purpose: The aim of this study was to determine the calcium levels in tooth enamel after being covered with CPP-ACP 2 times a day for 3, 14 and 28 days. Methods: Sample were bovine incisors of 3 year old cows divided into 4 groups, namely group I as control group, group II, III and IV as treatment groups covered with CPP-ACP 2 times a day. All of those teeth were then immersed in artificial saliva. Group II was immersed for 3 days, while group III was immersed for 14 days, and group IV was immersed for 28 days. One drop of CPP-ACP was used to cover the entire labial surface of teeth. The measurement of the calcium levels was then conducted by using titration method. All data were analyzed by One- Way ANOVA test with 5% degree of confidence. Results: The results showed significant difference of the calcium levels in tooth enamel of those groups after covered with CPP-ACP 2 times a day for 3, 14 and 28 days (p = 0.001. There is also significant difference of the calcium levels in tooth enamel of those treatment groups and the control group (p = 0.001. Conclusion: The calcium levels of tooth enamel are increased after covered with CPP-ACP 2 times a day for 3, 14 and 28 days.Latar belakang: Proses terjadinya karies gigi ditandai oleh adanya demineralisasi

  16. SUBSURFACE VISUAL ALARM SYSTEM ANALYSIS

    International Nuclear Information System (INIS)

    D.W. Markman

    2001-01-01

    The ''Subsurface Fire Hazard Analysis'' (CRWMS M andO 1998, page 61), and the document, ''Title III Evaluation Report for the Surface and Subsurface Communication System'', (CRWMS M andO 1999a, pages 21 and 23), both indicate the installed communication system is adequate to support Exploratory Studies Facility (ESF) activities with the exception of the mine phone system for emergency notification purposes. They recommend the installation of a visual alarm system to supplement the page/party phone system The purpose of this analysis is to identify data communication highway design approaches, and provide justification for the selected or recommended alternatives for the data communication of the subsurface visual alarm system. This analysis is being prepared to document a basis for the design selection of the data communication method. This analysis will briefly describe existing data or voice communication or monitoring systems within the ESF, and look at how these may be revised or adapted to support the needed data highway of the subsurface visual alarm. system. The existing PLC communication system installed in subsurface is providing data communication for alcove No.5 ventilation fans, south portal ventilation fans, bulkhead doors and generator monitoring system. It is given that the data communication of the subsurface visual alarm system will be a digital based system. It is also given that it is most feasible to take advantage of existing systems and equipment and not consider an entirely new data communication system design and installation. The scope and primary objectives of this analysis are to: (1) Briefly review and describe existing available data communication highways or systems within the ESF. (2) Examine technical characteristics of an existing system to disqualify a design alternative is paramount in minimizing the number of and depth of a system review. (3) Apply general engineering design practices or criteria such as relative cost, and degree

  17. Topographic assessment of human enamel surface treated with different topical sodium fluoride agents: Scanning electron microscope consideration

    Directory of Open Access Journals (Sweden)

    Gurlal Singh Brar

    2017-01-01

    Full Text Available Introduction: Continuous balanced demineralization and remineralization are natural dynamic processes in enamel. If the balance is interrupted and demineralization process dominates, it may eventually lead to the development of carious lesions in enamel and dentine. Fluoride helps control decay by enhancing remineralization and altering the structure of the tooth, making the surface less soluble. Methodology: One hundred and twenty sound human permanent incisors randomly and equally distributed into six groups as follows: Group I - Control, II - Sodium fluoride solution, III - Sodium fluoride gel, IV - Sodium fluoride varnish, V - Clinpro Tooth Crème (3M ESPE, and VI-GC Tooth Mousse Plus or MI Paste Plus. The samples were kept in artificial saliva for 12 months, and the topical fluoride agents were applied to the respective sample groups as per the manufacturer instructions. Scanning electron microscope (SEM evaluation of all the samples after 6 and 12 months was made. Results: Morphological changes on the enamel surface after application of fluoride in SEM revealed the presence of globular precipitate in all treated samples. Amorphous, globular, and crystalline structures were seen on the enamel surface of the treated samples. Clear differences were observed between the treated and untreated samples. Conclusion: Globular structures consisting of amorphous CaF2precipitates, which acted as a fluoride reservoir, were observed on the enamel surface after action of different sodium fluoride agents. CPP-ACPF (Tooth Mousse and Tricalcium phosphate with fluoride (Clinpro tooth crème are excellent delivery vehicles available in a slow release amorphous form to localize fluoride at the tooth surface.

  18. Dental enamel defects in children with coeliac disease

    NARCIS (Netherlands)

    Werink, Claar D.; van Diermen, Denise E.; Aartman, Irene H. A.; Heymans, Hugo S. A.

    2007-01-01

    OBJECTIVE: The aim of this study was to investigate whether Dutch children with proven coeliac disease show specific dental enamel defects, and to asses whether children with the same gastrointestinal complaints, but proved no-coeliac disease, lack these specific dental enamel defects. MATERIALS AND

  19. Brief communication: Enamel thickness and durophagy in mangabeys revisited.

    Science.gov (United States)

    McGraw, W Scott; Pampush, James D; Daegling, David J

    2012-02-01

    The documentation of enamel thickness variation across primates is important because enamel thickness has both taxonomic and functional relevance. The Old World monkeys commonly referred to as mangabeys have figured prominently in investigations of feeding ecology and enamel thickness. In this article, we report enamel thickness values for four mangabey taxa (Cercocebus atys, Cercocebus torquatus, Lophocebus aterrimus, and Lophocebus albigena), offer revised interpretation of the significance of thick enamel in papionin evolution, and place our new data in a broader comparative framework. Our data indicate that all mangabeys have thick enamel and that the values obtained for Cercocebus and Lophocebus equal or exceed those published for most extant non-human primates. In addition, new field data combined with a current reading of the dietary literature indicate that hard foods make up a portion of the diet of every mangabey species sampled to date. Clarification on the relationship between diet and enamel thickness among mangabeys is important not only because of recognition that mangabeys are not a natural group but also because of recent arguments that explain thick enamel as an evolved response to the seasonal consumption of hard foods. Copyright © 2011 Wiley Periodicals, Inc.

  20. Human enamel structure studied by high resolution electron microscopy

    International Nuclear Information System (INIS)

    Wen, S.L.

    1989-01-01

    Human enamel structural features are characterized by high resolution electron microscopy. The human enamel consists of polycrystals with a structure similar to Ca10(PO4)6(OH)2. This article describes the structural features of human enamel crystal at atomic and nanometer level. Besides the structural description, a great number of high resolution images are included. Research into the carious process in human enamel is very important for human beings. This article firstly describes the initiation of caries in enamel crystal at atomic and unit-cell level and secondly describes the further steps of caries with structural and chemical demineralization. The demineralization in fact, is the origin of caries in human enamel. The remineralization of carious areas in human enamel has drawn more and more attention as its potential application is realized. This process has been revealed by high resolution electron microscopy in detail in this article. On the other hand, the radiation effects on the structure of human enamel are also characterized by high resolution electron microscopy. In order to reveal this phenomenon clearly, a great number of electron micrographs have been shown, and a physical mechanism is proposed. 26 references

  1. Targeted overexpression of amelotin disrupts the microstructure of dental enamel.

    Science.gov (United States)

    Lacruz, Rodrigo S; Nakayama, Yohei; Holcroft, James; Nguyen, Van; Somogyi-Ganss, Eszter; Snead, Malcolm L; White, Shane N; Paine, Michael L; Ganss, Bernhard

    2012-01-01

    We have previously identified amelotin (AMTN) as a novel protein expressed predominantly during the late stages of dental enamel formation, but its role during amelogenesis remains to be determined. In this study we generated transgenic mice that produce AMTN under the amelogenin (Amel) gene promoter to study the effect of AMTN overexpression on enamel formation in vivo. The specific overexpression of AMTN in secretory stage ameloblasts was confirmed by Western blot and immunohistochemistry. The gross histological appearance of ameloblasts or supporting cellular structures as well as the expression of the enamel proteins amelogenin (AMEL) and ameloblastin (AMBN) was not altered by AMTN overexpression, suggesting that protein production, processing and secretion occurred normally in transgenic mice. The expression of Odontogenic, Ameloblast-Associated (ODAM) was slightly increased in secretory stage ameloblasts of transgenic animals. The enamel in AMTN-overexpressing mice was much thinner and displayed a highly irregular surface structure compared to wild type littermates. Teeth of transgenic animals underwent rapid attrition due to the brittleness of the enamel layer. The microstructure of enamel, normally a highly ordered arrangement of hydroxyapatite crystals, was completely disorganized. Tomes' process, the hallmark of secretory stage ameloblasts, did not form in transgenic mice. Collectively our data demonstrate that the overexpression of amelotin has a profound effect on enamel structure by disrupting the formation of Tomes' process and the orderly growth of enamel prisms.

  2. Role of crystal arrangement on the mechanical performance of enamel.

    Science.gov (United States)

    An, Bingbing; Wang, Raorao; Zhang, Dongsheng

    2012-10-01

    The superior mechanical properties of enamel, such as excellent penetration and crack resistance, are believed to be related to the unique microscopic structure. In this study, the effects of hydroxyapatite (HAP) crystallite orientation on the mechanical behavior of enamel have been investigated through a series of multiscale numerical simulations. A micromechanical model, which considers the HAP crystal arrangement in enamel prisms, the hierarchical structure of HAP crystals and the inelastic mechanical behavior of protein, has been developed. Numerical simulations revealed that, under compressive loading, plastic deformation progression took place in enamel prisms, which is responsible for the experimentally observed post-yield strain hardening. By comparing the mechanical responses for the uniform and non-uniform arrangement of HAP crystals within enamel prisms, it was found that the stiffness for the two cases was identical, while much greater energy dissipation was observed in the enamel with the non-uniform arrangement. Based on these results, we propose an important mechanism whereby the non-uniform arrangement of crystals in enamel rods enhances energy dissipation while maintaining sufficient stiffness to promote fracture toughness, mitigation of fracture and resistance to penetration deformation. Further simulations indicated that the non-uniform arrangement of the HAP crystals is a key factor responsible for the unique mechanical behavior of enamel, while the change in the nanostructure of nanocomposites could dictate the Young's modulus and yield strength of the biocomposite. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  3. Triad 'Metal – Enamel – Glass'

    International Nuclear Information System (INIS)

    Mukhina, T; Petrova, S; Toporova, V; Fedyaeva, T

    2014-01-01

    This article shows how to change the color of metal and glass. Both these materials are self–sufficient, but sometimes used together. For example, enameling. In this case, the adhesion between metal substrate and stekloobraznae enamel layer, which was conducted on a stretching and a bend, was tested

  4. Targeted overexpression of amelotin disrupts the microstructure of dental enamel.

    Directory of Open Access Journals (Sweden)

    Rodrigo S Lacruz

    Full Text Available We have previously identified amelotin (AMTN as a novel protein expressed predominantly during the late stages of dental enamel formation, but its role during amelogenesis remains to be determined. In this study we generated transgenic mice that produce AMTN under the amelogenin (Amel gene promoter to study the effect of AMTN overexpression on enamel formation in vivo. The specific overexpression of AMTN in secretory stage ameloblasts was confirmed by Western blot and immunohistochemistry. The gross histological appearance of ameloblasts or supporting cellular structures as well as the expression of the enamel proteins amelogenin (AMEL and ameloblastin (AMBN was not altered by AMTN overexpression, suggesting that protein production, processing and secretion occurred normally in transgenic mice. The expression of Odontogenic, Ameloblast-Associated (ODAM was slightly increased in secretory stage ameloblasts of transgenic animals. The enamel in AMTN-overexpressing mice was much thinner and displayed a highly irregular surface structure compared to wild type littermates. Teeth of transgenic animals underwent rapid attrition due to the brittleness of the enamel layer. The microstructure of enamel, normally a highly ordered arrangement of hydroxyapatite crystals, was completely disorganized. Tomes' process, the hallmark of secretory stage ameloblasts, did not form in transgenic mice. Collectively our data demonstrate that the overexpression of amelotin has a profound effect on enamel structure by disrupting the formation of Tomes' process and the orderly growth of enamel prisms.

  5. Chymotrypsin C (Caldecrin) Is Associated with Enamel Development

    Science.gov (United States)

    Lacruz, R.S.; Smith, C.E.; Smith, S.M.; Hu, P.; Bringas, P.; Sahin-Tóth, M.; Moradian-Oldak, J.; Paine, M.L.

    2011-01-01

    Two main proteases cleave enamel extracellular matrix proteins during amelogenesis. Matrix metalloprotease-20 (Mmp20) is the predominant enzyme expressed during the secretory stage, while kallikrein-related peptidase-4 (Klk4) is predominantly expressed during maturation. Mutations to both Mmp20 and Klk4 result in abnormal enamel phenotypes. During a recent whole-genome microarray analysis of rat incisor enamel organ cells derived from the secretory and maturation stages of amelogenesis, the serine protease chymotrypsin C (caldecrin, Ctrc) was identified as significantly up-regulated (> 11-fold) during enamel maturation. Prior reports indicate that Ctrc expression is pancreas-specific, albeit low levels were also noted in brain. We here report on the expression of Ctrc in the enamel organ. Quantitative PCR (qPCR) and Western blot analysis were used to confirm the expression of Ctrc in the developing enamel organ. The expression profile of Ctrc is similar to that of Klk4, increasing markedly during the maturation stage relative to the secretory stage, although levels of Ctrc mRNA are lower than for Klk4. The discovery of a new serine protease possibly involved in enamel development has important implications for our understanding of the factors that regulate enamel biomineralization. PMID:21828354

  6. A comparison of terahertz-pulsed imaging with transverse microradiography and microhardness to measure mineral changes in enamel after treatment with fluoride dentifrices

    Science.gov (United States)

    Churchley, David; Lippert, Frank; Lynch, Richard; Alton, Jesse; Gonzalez-Cabezas, C.; Eder, J.

    2009-02-01

    The aim of this study was to determine the ability of Terahertz Pulsed Imaging (TPI) to measure mineral changes in enamel lesions during de/remineralisation studies. A comparison was made between transverse microradiography (TMR) and microhardness measurements. Artificial lesions were formed in bovine enamel using a solution of 0.1 M lactic acid (pH 5.0) containing 0.2% Carbopol C907 and 50% saturated with hydroxyapatite. The 20 day experimental protocol consisted of four, one-minute treatment periods with dentifrices containing 10, 675, 1385 and 2700ppm fluoride, a 4 h/day acid challenge, and for the remaining time specimens were stored in a 50:50 pooled human / artificial saliva mixture. Terahertz images were generated by positioning the specimens at the focus of the beam and raster scanning the optics to collect the reflections from the air / enamel (AEI) and lesion / enamel (LEI) interface. Significant differences were observed in the intensity change from baseline of the AEI and LEI reflections upon treatment with the four dentifrices. A linear correlation was observed between ΔAEI vs ΔVHN (r2 = 0.997), ΔAEI vs ΔKHN (r2 =0.964), ΔII (ratio of LEI to AEI) vs ΔΔZ (r2 =0.875) and ΔLEI vs ΔΔZ (r2 =0.870). Statistically significant correlations (ptechnology to measure in vitro (and possibly in situ) mineral changes in enamel and is sufficiently sensitive to discriminate between the levels of remineralization produced by the different dentifrices.

  7. ONLINE TECHNOLOGICAL MONITORING OF INSULATION DEFECTS IN ENAMELED WIRES

    Directory of Open Access Journals (Sweden)

    V. M. Zolotaryov

    2017-08-01

    Full Text Available In this paper the authors used non-destructive technological monitoring of defects insulation enameled wire with poliimid polymer. The paper is devoted to the statistical method for processing, comparison and analysis of results of measurements of parameters of insulation of enameled wire because of mathematical model of trend for application in active technological monitoring is developed; the recommendations for parameters of such monitoring are used. It is theoretically justified and the possibility of determination of dependence of the error on the velocity of movement of a wire for want of quantifying of defects in enameled insulation by non-destructive tests by high voltage. The dependence of average value of amount of defects for enameled wire with two-sheeted poliimid insulation in a range of nominal diameter 0.56 mm is experimentally determined. The technological monitoring purpose is to reduce the quantifying defects of enameled insulation.

  8. Integrated geomechanical modelling for deep subsurface damage

    NARCIS (Netherlands)

    Wees, J.D. van; Orlic, B.; Zijl, W.; Jongerius, P.; Schreppers, G.J.; Hendriks, M.

    2001-01-01

    Government, E&P and mining industry increasingly demand fundamental insight and accurate predictions on subsurface and surface deformation and damage due to exploitation of subsurface natural resources, and subsurface storage of energy residues (e.g. CO2). At this moment deformation is difficult to

  9. Effect of various tooth-whitening products on enamel microhardness.

    Science.gov (United States)

    Grobler, S R; Majeed, A; Moola, M H

    2009-11-01

    The purpose of this in vitro study was to evaluate the effect of various tooth-whitening products containing carbamide peroxide (CP) or hydrogen peroxide (HP), on enamel microhardness. Enamel blocks were exposed to: Nite White ACP 10% CP (Group 2, n=10); Yotuel Patient 10% CP (Group 3, n=10); Opalescence PF 10% CP (Group 4, n=10); Opalescence PF 20% CP (Group 5, n=10); Opalescence Treswhite Supreme 10% HP (Group 6, n=10); Yotuel 10 Minutes 30% CP (Group 7, n=10); Opalescence Quick 45% CP (Group 8, n=10), Yotuel Special 35% HP (Group 9, n=10), Opalescence Boost 38% HP (Group 10, n=10) according to the instructions of the manufacturers. The control (Group 1, n=10) was enamel blocks kept in artificial saliva at 37 degrees C without any treatment. The microhardness values were obtained before exposure and after a 14-day treatment period. Specimens were kept in artificial saliva at 37 degrees C between treatments. Data were analysed using Kruskal-Wallis one-way ANOVA and Tukey-Kramer Multiple Comparison Test. Indent marks on the enamel blocks were also examined under the Scanning Electron Microscope. All whitening products decreased enamel microhardness except group 10 but only Groups 2, 3, 4, 5 and 7 showed significant decrease in enamel microhardness as compared to the control group (p enamel. All products tested in this study decreased enamel microhardness except Opalescence Boost 38% HP. The products containing carbamide peroxide were more damaging to enamel because of the longer application times. Nite White ACP 10% CP showed the highest reduction in enamel microhardness as compared to other products tested.

  10. Keratins as components of the enamel organic matrix

    Science.gov (United States)

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

    2016-01-01

    Dental enamel is a 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 150 years. 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

  11. Indentation damage and mechanical properties of human enamel and dentin.

    Science.gov (United States)

    Xu, H H; Smith, D T; Jahanmir, S; Romberg, E; Kelly, J R; Thompson, V P; Rekow, E D

    1998-03-01

    Understanding the mechanical properties of human teeth is important to clinical tooth preparation and to the development of "tooth-like" restorative materials. Previous studies have focused on the macroscopic fracture behavior of enamel and dentin. In the present study, we performed indentation studies to understand the microfracture and deformation and the microcrack-microstructure interactions of teeth. It was hypothesized that crack propagation would be influenced by enamel rods and the dentino-enamel junction (DEJ), and the mechanical properties would be influenced by enamel rod orientation and tooth-to-tooth variation. Twenty-eight human third molars were used for the measurement of hardness, fracture toughness, elastic modulus, and energy absorbed during indentation. We examined the effect of enamel rod orientation by propagating cracks in the occlusal surface, and in the axial section in directions parallel and perpendicular to the occlusal surface. The results showed that the cracks in the enamel axial section were significantly longer in the direction perpendicular to the occlusal surface than parallel. The cracks propagating toward the DEJ were always arrested and unable to penetrate dentin. The fracture toughness of enamel was not single-valued but varied by a factor of three as a function of enamel rod orientation. The elastic modulus of enamel showed a significant difference between the occlusal surface and the axial section. It is concluded that the cracks strongly interact with the DEJ and the enamel rods, and that the mechanical properties of teeth are functions of microstructural orientations; hence, single values of properties (e.g., a single toughness value or a single modulus value) should not be used without information on microstructural orientation.

  12. Enamel microstructure and microstrain in the fracture of human and pig molar cusps.

    Science.gov (United States)

    Popowics, T E; Rensberger, J M; Herring, S W

    2004-08-01

    The role of microstructure in enamel strain and breakage was investigated in human molar cusps and those of the pig, Sus scrofa. Rosette strain gauges were affixed to cusp surfaces (buccal human M3, n=15, and lingual pig M1, n=13), and a compressive load was applied to individual cusps using an MTS materials testing machine. Load and strain data were recorded simultaneously until cusp fracture, and these data were used to estimate enamel stresses, principal strains, and stiffness. Fractured and polished enamel fragments were examined in multiple planes using scanning electron microscopy (SEM). Human cusp enamel showed greater stiffness than pig enamel (P=0.02), and tensile stress at yield was higher (17.9 N/mm2 in humans versus 8.9 N/mm2 in pigs, P=0.06). SEM revealed enamel rod decussation in both human and pig enamel; however, only pig enamel showed a decussation plane between rod and inter-rod crystallites. Human inter-rod enamel was densely packed between rods, whereas in pig enamel, inter-rod enamel formed partitions between rows of enamel rods. Overall, human enamel structure enabled molar cusps to withstand horizontal tensile stress during both elastic and plastic phases of compressive loading. In contrast, pig cusp enamel was less resistant to horizontal tensile stresses, but appeared to fortify the enamel against crack propagation in multiple directions. These structural and biomechanical differences in cusp enamel are likely to reflect species-level differences in occlusal function.

  13. Gold Enamel Choumps – A Case report

    Directory of Open Access Journals (Sweden)

    Sargam D. Kotecha

    2016-09-01

    Full Text Available Tooth jewellery has been practiced since time immemorial and has become an increasingly popular trend. This case report provides a brief insight into a kind of tooth adornment/a tooth tattoo on the enamel prevalent in parts of western Uttar Pradesh, India locally known as a ‘Choump’. A tooth tattooed with ‘Choumps’ has extremely low incidence and could be used as an identification trait. Tooth adornment with ‘Choumps’ has been reported in adults however, this is the first reported case of ‘Choumps’ in children.

  14. Comparison of shear bond strength between unfilled resin to dry enamel and dentin bonding to moist and dry enamel

    Directory of Open Access Journals (Sweden)

    Yasini E.

    2005-05-01

    Full Text Available Statement of Problem: The use of dentine bondings on enamel and dentin in total etch protocols has recently become popular. Unfilled resin is hydrophobic and dentin bonding is hydrophilic in nature. This chemical difference could be effective in enamel bonding process. Purpose: The aim of this study was to compare the shear bond strength of unfilled resin to dry enamel and dentin bonding to dry and moist enamel. Materials and Methods: In this experimental study, a total of 30 incisor teeth were used. The specimens were randomly assigned to three groups of 10. 37% phosphoric acid etchant was applied to the enamel surfaces in each group for 15 seconds, rinsed with water for 20 seconds and dried for 20 seconds with compressed air in groups one and two. After conditioning, group 1 received unfilled resin (Margin Bond, Colten and group 2 received dentin bonding (Single Bond, 3M and in group 3 after conditioning and rinsing with water, a layer of dentin bonding (Single Bond was applied on wet enamel. The enamel and dentin bonding were light cured for 20 seconds. A ring mold 3.5 mm in diameter and 2 mm height was placed over the specimens to receive the composite filling material (Z100, 3M. The composite was cured for 40 seconds. The specimens were thermocycled and shear bond strengths were determined using an Instron Universal Testing Machine. The findings were analyzed by ANOVA One-Way and Tukey HSD tests. Results: Shear bond strength of dentin bonding to dry enamel was significantly less than unfilled resin to dry enamel (P<0.05. There was no significant difference between the bond strength of dentin bonding to moist and dry enamel. In addition bond strength of dentin bonding to wet enamel was not significantly different from unfilled resin to dry enamel. Conclusion: Based on the findings of this study, it is suggested that enamel surface should remain slightly moist after etching before bonding with single bond but when using unfilled resin, the

  15. Subsurface Noble Gas Sampling Manual

    Energy Technology Data Exchange (ETDEWEB)

    Carrigan, C. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Sun, Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-09-18

    The intent of this document is to provide information about best available approaches for performing subsurface soil gas sampling during an On Site Inspection or OSI. This information is based on field sampling experiments, computer simulations and data from the NA-22 Noble Gas Signature Experiment Test Bed at the Nevada Nuclear Security Site (NNSS). The approaches should optimize the gas concentration from the subsurface cavity or chimney regime while simultaneously minimizing the potential for atmospheric radioxenon and near-surface Argon-37 contamination. Where possible, we quantitatively assess differences in sampling practices for the same sets of environmental conditions. We recognize that all sampling scenarios cannot be addressed. However, if this document helps to inform the intuition of the reader about addressing the challenges resulting from the inevitable deviations from the scenario assumed here, it will have achieved its goal.

  16. Changes in surface morphology of enamel after Er:YAG laser irradiation

    Science.gov (United States)

    Rechmann, Peter; Goldin, Dan S.; Hennig, Thomas

    1998-04-01

    Aim of the study was to investigate the surface and subsurface structure of enamel after irradiation with an Er:YAG laser (wavelength 2.94 micrometer, pulse duration 250 - 500 microseconds, free running, beam profile close to tophead, focus diameter 600 micrometer, focus distance 13 mm, different power settings, air-water spray 2 ml/min; KAVO Key Laser 1242, Kavo Biberach, Germany). The surface of more than 40 freshly extracted wisdom teeth were irradiated using a standardized application protocol (pulse repetition rate 4 and 6 Hz, moving speed of the irradiation table 2 mm/sec and 3 mm/sec, respectively). On each surface between 3 and 5 tracks were irradiated at different laser energies (60 - 500 mJ/pulse) while each track was irradiated between one and ten times respectively. For the scanning electron microscope investigation teeth were dried in alcohol and sputtered with gold. For light microscopic examinations following laser impact, samples were fixed in formaldehyde, dried in alcohol and embedded in acrylic resin. Investigations revealed that at subsurface level cracks can not be observed even at application of highest energies. Borders of the irradiated tracks seem to be sharp while melted areas of different sizes are observed on the bottom of the tracks depending on applied energy. Small microcracks can be seen on the surface of these melted areas.

  17. Enamel formation in vitro in mouse molar explants exposed to amelogenin polypeptides ATMP and LRAP on enamel development.

    Science.gov (United States)

    Ravindranath, Rajeswari M H; Devarajan, Asokan; Bringas, Pablo

    2007-12-01

    The enamel matrix contains amelogenin, leucine-rich amelogenin-polypeptide (LRAP), resulting from alternative splicing of the primary amelogenin-RNA transcript and tyrosine-rich amelogenin-polypeptide (TRAP), a proteolytic product of amelogenin. Presence of amelogenin-trityrosyl-motif peptide (ATMP) distinguishes TRAP from LRAP. The roles of these polypeptides in the formation of enamel remain to be elucidated. The mouse in vitro molar tooth-organ developed from bud stage (E16) was exposed to LRAP, ATMP, and mutated ATMP (T-ATMP, third proline replaced by threonine). The histology and morphometry of the explants on day-12 in culture was examined using Mallory's stain. Guanidine-HCl soluble protein concentrations of explants were compared. The enamel width and protein solubility indicate that the explant on day-12 is comparable to postnatal molar on day-3 in vivo. The enamel of both untreated explants as well as that in vivo is fuchinophilic (acid fuchsin, AF+). ATMP reduced the ameloblast-height, accumulated AF+ spherules at the apical end of ameloblasts, and disrupted enamel-dentin bonding. T-ATMP abrogated deposition of AF+ material on the aniline blue positive (AB+) enamel matrix. LRAP reduced ameloblast-height, increased the enamel-width without disruption (at 17.25 nmol) and increased the density of AF+ dentinal tubules. AF+ substance from the tubules is released onto the surface of the dentin. The Guanidine-HCl-soluble protein is elevated in ATMP-treated explants but decreased in LRAP-treated explants. Exogenous ATMP, T-ATMP and LRAP have divergent effects on developing enamel. Exogenous ATMP, but not LRAP, abrogates enamel-dentin bonding at 17.25 nmol. LRAP may play a role in the differentiation of ameloblasts, growth of enamel and formation of dentinal tubules.

  18. VISUALIZATION OF REGISTERED SUBSURFACE ANATOMY

    DEFF Research Database (Denmark)

    2010-01-01

    A system and method for visualization of subsurface anatomy includes obtaining a first image from a first camera and a second image from a second camera or a second channel of the first camera, where the first and second images contain shared anatomical structures. The second camera and the secon....... A visual interface displays the registered visualization of the first and second images. The system and method are particularly useful for imaging during minimally invasive surgery, such as robotic surgery....

  19. Geophysical characterization of subsurface barriers

    International Nuclear Information System (INIS)

    Borns, D.J.

    1995-08-01

    An option for controlling contaminant migration from plumes and buried waste sites is to construct a subsurface barrier of a low-permeability material. The successful application of subsurface barriers requires processes to verify the emplacement and effectiveness of barrier and to monitor the performance of a barrier after emplacement. Non destructive and remote sensing techniques, such as geophysical methods, are possible technologies to address these needs. The changes in mechanical, hydrologic and chemical properties associated with the emplacement of an engineered barrier will affect geophysical properties such a seismic velocity, electrical conductivity, and dielectric constant. Also, the barrier, once emplaced and interacting with the in situ geologic system, may affect the paths along which electrical current flows in the subsurface. These changes in properties and processes facilitate the detection and monitoring of the barrier. The approaches to characterizing and monitoring engineered barriers can be divided between (1) methods that directly image the barrier using the contrasts in physical properties between the barrier and the host soil or rock and (2) methods that reflect flow processes around or through the barrier. For example, seismic methods that delineate the changes in density and stiffness associated with the barrier represents a direct imaging method. Electrical self potential methods and flow probes based on heat flow methods represent techniques that can delineate the flow path or flow processes around and through a barrier

  20. Subsurface transport program: Research summary

    International Nuclear Information System (INIS)

    1987-01-01

    DOE's research program in subsurface transport is designed to provide a base of fundamental scientific information so that the geochemical, hydrological, and biological mechanisms that contribute to the transport and long term fate of energy related contaminants in subsurface ecosystems can be understood. Understanding the physical and chemical mechanisms that control the transport of single and co-contaminants is the underlying concern of the program. Particular attention is given to interdisciplinary research and to geosphere-biosphere interactions. The scientific results of the program will contribute to resolving Departmental questions related to the disposal of energy-producing and defense wastes. The background papers prepared in support of this document contain additional information on the relevance of the research in the long term to energy-producing technologies. Detailed scientific plans and other research documents are available for high priority research areas, for example, in subsurface transport of organic chemicals and mixtures and in the microbiology of deep aquifers. 5 figs., 1 tab

  1. Testing functional and morphological interpretations of enamel thickness along the deciduous tooth row in human children.

    OpenAIRE

    Mahoney, Patrick

    2013-01-01

    The significance of a gradient in enamel thickness along the human permanent molar row has been debated in the literature. Some attribute increased enamel thickness from first to third molars to greater bite force during chewing. Others argue that thicker third molar enamel relates to a smaller crown size facilitated by a reduced dentin component. Thus, differences in morphology, not function, explains enamel thickness. This study draws on these different interpretive models to assess enamel ...

  2. Role of Prism Decussation on Fatigue Crack Growth and Fracture of Human Enamel

    OpenAIRE

    Bajaj, Devendra; Arola, Dwayne

    2009-01-01

    The role of prism decussation on the crack growth resistance of human enamel is evaluated. Miniature inset Compact Tension (CT) specimens embodying a section of cuspal enamel were subjected to Mode I cyclic or monotonic loads. Cracks were grown in either the forward (from outer enamel inwards) or reverse (from inner enamel outwards) direction and the responses were compared quantitatively. Results showed that the outer enamel exhibits lower resistance to the inception and growth of cracks. Re...

  3. Enamel Defects Reflect Perinatal Exposure to Bisphenol A

    Science.gov (United States)

    Jedeon, Katia; De la Dure-Molla, Muriel; Brookes, Steven J.; Loiodice, Sophia; Marciano, Clémence; Kirkham, Jennifer; Canivenc-Lavier, Marie-Chantal; Boudalia, Sofiane; Bergès, Raymond; Harada, Hidemitsu; Berdal, Ariane; Babajko, Sylvie

    2014-01-01

    Endocrine-disrupting chemicals (EDCs), including bisphenol A (BPA), are environmental ubiquitous pollutants and associated with a growing health concern. Anecdotally, molar incisor hypomineralization (MIH) is increasing concurrently with EDC-related conditions, which has led us to investigate the effect of BPA on amelogenesis. Rats were exposed daily to BPA from conception until day 30 or 100. At day 30, BPA-affected enamel exhibited hypomineralization similar to human MIH. Scanning electron microscopy and elemental analysis revealed an abnormal accumulation of organic material in erupted enamel. BPA-affected enamel had an abnormal accumulation of exogenous albumin in the maturation stage. Quantitative real-timePCR, Western blotting, and luciferase reporter assays revealed increased expression of enamelin but decreased expression of kallikrein 4 (protease essential for removing enamel proteins) via transcriptional regulation. Data suggest that BPA exerts its effects on amelogenesis by disrupting normal protein removal from the enamel matrix. Interestingly, in 100-day-old rats, erupting incisor enamel was normal, suggesting amelogenesis is only sensitive to MIH-causing agents during a specific time window during development (as reported for human MIH). The present work documents the first experimental model that replicates MIH and presents BPA as a potential causative agent of MIH. Because human enamel defects are irreversible, MIH may provide an easily accessible marker for reporting early EDC exposure in humans. PMID:23764278

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

    Science.gov (United States)

    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

  5. DESIGN AND APPLICATION OF TRANSPARENT AND TRANSLUCENT ENAMELS ON ALUMINUM

    Directory of Open Access Journals (Sweden)

    H. AHMADI MOGHADDAM

    2012-09-01

    Full Text Available Transparent and opaque glass enamels for aluminum plates were designed with a minimum or with no heavy atom oxides such as lead and bismuth oxides. The thermal properties of the enamels were studied by DTA and their stability as measured by the difference of glass transition and crystallization onset temperatures was determined. Bending and rapid deformation (impact tests indicated the interfacial adhesion. The enamel/aluminum interfacial qualities were viewed and examined by scanning electron microscopy (SEM. A large amount of NaF and P2O5 in their formulation created opaque enamels. The three methods of melt dipping, pouring, and sintering were used to apply layers of enamels on aluminum plates. The novelty of the pouring and spreading method and its advantages over other methods, were in the use of lower stability and higher melting point enamels, without thermally/mechanically damaging the aluminum. Observations suggested that the interfacial contact and adhesion properties were good, particularly with the transparent or glassy state enamels.

  6. Spatial distribution of the human enamel fracture toughness with aging.

    Science.gov (United States)

    Zheng, Qinghua; Xu, Haiping; Song, Fan; Zhang, Lan; Zhou, Xuedong; Shao, Yingfeng; Huang, Dingming

    2013-10-01

    A better understanding of the fracture toughness (KIC) of human enamel and the changes induced by aging is important for the clinical treatment of teeth cracks and fractures. We conducted microindentation tests and chemical content measurements on molar teeth from "young" (18 ≤ age ≤ 25) and "old" (55 ≤ age) patients. The KIC and the mineral contents (calcium and phosphorus) in the outer, the middle, and the inner enamel layers within the cuspal and the intercuspal regions of the crown were measured through the Vickers toughness test and Energy Dispersive X-Ray Spectroscopy (EDS), respectively. The elastic modulus used for the KIC calculation was measured through atomic force microscope (AFM)-based nanoindentation tests. In the outer enamel layer, two direction-specific values of the KIC were calculated separately (direction I, crack running parallel to the occlusal surface; direction II, perpendicular to direction I). The mean KIC of the outer enamel layer was lower than that of the internal layers (penamel layer, old enamel has a lower KIC, II and higher mineral contents than young enamel (penamel surface becomes more prone to cracks with aging partly due to the reduction in the interprismatic organic matrix observed with the maturation of enamel. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. A novel biomimetic orthodontic bonding agent helps prevent white spot lesions adjacent to brackets.

    Science.gov (United States)

    Manfred, Lauren; Covell, David A; Crowe, Jennifer J; Tufekci, Eser; Mitchell, John C

    2013-01-01

    To compare changes in enamel microhardness adjacent to orthodontic brackets after using bonding agents containing various compositions of bioactive glass compared to a traditional resin adhesive following a simulated caries challenge. Extracted human third molars (n  =  10 per group) had orthodontic brackets bonded using one of four novel bioactive glass (BAG)-containing orthodontic bonding agents (BAG-Bonds) or commercially available Transbond-XT. The four new adhesives contained BAG in varying percentages incorporated into a traditional resin monomer mixture. Teeth were cycled through low-pH demineralizing and physiologic-pH remineralizing solutions once each day over 14 days. Microhardness was measured on longitudinal sections of the teeth 100, 200, and 300 µm from the bracket edge and beneath the brackets, at depths of 25 to 200 µm from the enamel surface. Normalized hardness values were compared using three-way analysis of variance. Significantly less reduction in enamel microhardness was found with the experimental adhesives at depths of 25 and 50 µm at all distances from the bracket edge. In all groups, there were no significant changes in enamel microhardness past 125-µm depth. Results varied with the different BAG-Bonds, with 81BAG-Bond showing the smallest decrease in enamel microhardness. The BAG-Bonds tested in this study showed a reduction in the amount of superficial enamel softening surrounding orthodontic brackets compared to a traditional bonding agent. The results indicate that clinically, BAG-Bonds may aid in maintaining enamel surface hardness, therefore helping prevent white spot lesions adjacent to orthodontic brackets.

  8. In vitro evaluation of casein phosphopeptide-amorphous calcium phosphate effect on the shear bond strength of dental adhesives to enamel.

    Science.gov (United States)

    Shadman, Niloofar; Ebrahimi, Shahram Farzin; Shoul, Maryam Azizi; Sattari, Hasti

    2015-01-01

    Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is applied for remineralization of early caries lesions or tooth sensitivity conditions and may affect subsequent resin bonding. This in vitro study investigated the effect of CPP-ACP on the shear bond strength of dental adhesives to enamel. Sixty extracted human molar teeth were selected and randomly divided into three groups and six subgroups. Buccal or lingual surfaces of teeth were prepared to create a flat enamel surface. Adhesives used were Tetric N-Bond, AdheSE and AdheSE One F. In three subgroups, before applying adhesives, enamel surfaces were treated with Tooth Mousse CPP-ACP for one hour, rinsed and stored in 37°C temperature with 100% humidity. This procedure was repeated for 5 days and then adhesives were applied and Tetric N-Ceram composite was adhered to the enamel. This procedure was also fulfilled for the other three subgroups without CPP-ACP treatment. After 24 hour water storage, samples were tested for shear bond strength test in a universal testing machine. Failure modes were determined by stereomicroscope. Data were analyzed by t-test and one-way analysis of variance with P enamel only in Tetric N-Bond (P > 0.05). In non-applied CPP-ACP subgroups, there were statistically significant differences among all subgroups. Tetric N-Bond had the highest and AdheSE One F had the lowest shear bond strength. CPP-ACP application reduces the shear bond strength of AdheSE and AdheSE One F to enamel but not Tetric N-Bond.

  9. Microstructure and hardness of bovine enamel in roselle extract solution

    Science.gov (United States)

    Dame, M. T.; Noerdin, A.; Indrani, D. J.

    2017-08-01

    The aim of this study was to analyze the effect of roselle extract solution on the microstructure and hardness of bovine enamel. Ten bovine teeth and a 5% concentration of roselle extract solution were prepared. Immersions of each bovine tooth in roselle extract solution were conducted up to 60 minutes. The bovine enamel surface was characterized in hardness and microscopy. It was apparent that the initial hardness was 328 KHN, and after immersion in 15 and 60 min, the values decrease to 57.4 KHN and 11 KHN, respectively. Scanning electron microscopy (SEM) revealed changes in enamel rods after immersion in the roselle extract solution.

  10. Chromatographic separation of alkaline phosphatase from dental enamel

    DEFF Research Database (Denmark)

    Moe, D; Kirkeby, S; Salling, E

    1989-01-01

    Alkaline phosphatase (AP) was prepared from partly mineralized bovine enamel by extraction in phosphate buffer, centrifugation and various chromatographic techniques. Chromatofocusing showed that the enamel enzyme possessed five isoelectric points at the acid pH level ranging from pH 5.7 to pH 4.......4. Three enzyme peaks were eluted using low pressure chromatography with a Bio-gel column. With a HPLC gel filtration column the separation of the enamel extract resulted in only one peak with AP activity. The fractions of this peak were used to produce an antibody against bovine AP....

  11. Thermal cycling effects on adhesion of resin-bovine enamel junction among different composite resins.

    Science.gov (United States)

    Chen, Wen-Cheng; Ko, Chia-Ling; Wu, Hui-Yu; Lai, Pei-Ling; Shih, Chi-Jen

    2014-10-01

    Thermal cycling is used to mimic the changes in oral cavity temperature experienced by composite resins when used clinically. The purpose of this study is to assess the thermal cycling effects of in-house produced composite resin on bonding strength. The dicalcium phosphate anhydrous filler surfaces are modified using nanocrystals and silanization (w/NP/Si). The resin is compared with commercially available composite resins Filtek Z250, Z350, and glass ionomer restorative material GIC Fuji-II LC (control). Different composite resins were filled into the dental enamel of bovine teeth. The bond force and resin-enamel junction graphical structures of the samples were determined after thermal cycling between 5 and 55°C in deionized water for 600 cycles. After thermal cycling, the w/NP/Si 30wt%, 50wt% and Filtek Z250, Z350 groups showed higher shear forces than glass ionomer GIC, and w/NP/Si 50wt% had the highest shear force. Through SEM observations, more of the fillings with w/NP/Si 30wt% and w/NP/Si 50wt% groups flowed into the enamel tubule, forming closed tubules with the composite resins. The push-out force is proportional to the resin flow depth and uniformity. The push-out tubule pore and resin shear pattern is the most uniform and consistent in the w/NP/Si 50wt% group. Accordingly, this developed composite resin maintains great mechanical properties after thermal cycling. Thus, it has the potential to be used in a clinical setting when restoring non-carious cervical lesions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. In vitro study of hydroxy apatite and enamel powder fused in human enamel by Nd:YAG laser

    International Nuclear Information System (INIS)

    Ferrreira, Marcus Vinicius Lucas

    2000-01-01

    The aim of this study was to evaluate the effects of pulsed Nd:YAG (1064 nm) laser irradiation on hydroxyapatite and enamel powder fusion. This laser beam is not well absorbed by this two compounds for this reason they were mixed with vegetal coal to increase the absorption of the laser beam. Fifteen enamel flat surfaces and six occlusal enamel surfaces were prepared with three different substances: hydroxyapatite mixed with vegetal coal (3:1 in weigh); enamel powder mixed with vegetal coal (3:1 in weigh); vegetal coal. The occlusal surfaces were utilized to determine if the compounds could seal pits and fissures. Flat surfaces were utilized to determine fusion of hydroxyapatite and enamel powder. All samples were irradiated with Nd:YAG laser with the parameters: 80 mJ, 15 Hz, 1,2 W, 100 μs pulse-width, 131,1 J/cm 2 . Laser beam was delivered to the samples with a 300 μm diameter fiber optic. Morphology of the irradiated surfaces were examined by scanning electron microscopy (SEM). The compounds with hydroxyapatite and enamel powder were fused to enamel surfaces. Only partial pits and fissures sealing could be observed. (author)

  13. Metatranscriptomics reveals overall active bacterial composition in caries lesions

    Directory of Open Access Journals (Sweden)

    Aurea Simón-Soro

    2014-10-01

    Full Text Available Background: Identifying the microbial species in caries lesions is instrumental to determine the etiology of dental caries. However, a significant proportion of bacteria in carious lesions have not been cultured, and the use of molecular methods has been limited to DNA-based approaches, which detect both active and inactive or dead microorganisms. Objective: To identify the RNA-based, metabolically active bacterial composition of caries lesions at different stages of disease progression in order to provide a list of potential etiological agents of tooth decay. Design: Non-cavitated enamel caries lesions (n=15 and dentin caries lesions samples (n=12 were collected from 13 individuals. RNA was extracted and cDNA was constructed, which was used to amplify the 16S rRNA gene. The resulting 780 bp polymerase chain reaction products were pyrosequenced using Titanium-plus chemistry, and the sequences obtained were used to determine the bacterial composition. Results: A mean of 4,900 sequences of the 16S rRNA gene with an average read length of 661 bp was obtained per sample, giving a comprehensive view of the active bacterial communities in caries lesions. Estimates of bacterial diversity indicate that the microbiota of cavities is highly complex, each sample containing between 70 and 400 metabolically active species. The composition of these bacterial consortia varied among individuals and between caries lesions of the same individuals. In addition, enamel and dentin lesions had a different bacterial makeup. Lactobacilli were found almost exclusively in dentin cavities. Streptococci accounted for 40% of the total active community in enamel caries, and 20% in dentin caries. However, Streptococcus mutans represented only 0.02–0.73% of the total bacterial community. Conclusions: The data indicate that the etiology of dental caries is tissue dependent and that the disease has a clear polymicrobial origin. The low proportion of mutans streptococci

  14. Treatment of a Periodontic-Endodontic Lesion in a Patient with Aggressive Periodontitis.

    Science.gov (United States)

    Fahmy, Mina D; Luepke, Paul G; Ibrahim, Mohamed S; Guentsch, Arndt

    2016-01-01

    Case Description. This case report describes the successful management of a left mandibular first molar with a combined periodontic-endodontic lesion in a 35-year-old Caucasian woman with aggressive periodontitis using a concerted approach including endodontic treatment, periodontal therapy, and a periodontal regenerative procedure using an enamel matrix derivate. In spite of anticipated poor prognosis, the tooth lesion healed. This case report also discusses the rationale behind different treatment interventions. Practical Implication. Periodontic-endodontic lesions can be successfully treated if dental professionals follow a concerted treatment protocol that integrates endodontic and periodontic specialties. General dentists can be the gatekeepers in managing these cases.

  15. Treatment of a Periodontic-Endodontic Lesion in a Patient with Aggressive Periodontitis

    Directory of Open Access Journals (Sweden)

    Mina D. Fahmy

    2016-01-01

    Full Text Available Case Description. This case report describes the successful management of a left mandibular first molar with a combined periodontic-endodontic lesion in a 35-year-old Caucasian woman with aggressive periodontitis using a concerted approach including endodontic treatment, periodontal therapy, and a periodontal regenerative procedure using an enamel matrix derivate. In spite of anticipated poor prognosis, the tooth lesion healed. This case report also discusses the rationale behind different treatment interventions. Practical Implication. Periodontic-endodontic lesions can be successfully treated if dental professionals follow a concerted treatment protocol that integrates endodontic and periodontic specialties. General dentists can be the gatekeepers in managing these cases.

  16. External resorption presenting as an intracoronal radiolucent lesion in a pre-eruptive tooth.

    LENUS (Irish Health Repository)

    McNamara, C M

    1997-09-01

    A large intracoronal radiolucent lesion in an unerupted permanent molar was found during the routine assessment of a young male Caucasian prior to orthodontic treatment. The tooth was extracted. Histological examination indicated the lesion was caused by external resorption. The defect extended widely into the enamel and dentine, and was repaired in part by bone. The pulp chamber was not involved. The aetiology of these lesions is often obscure but in this case it appeared to have originated in the floor of two developmental pits on the occlusal surface of the tooth.

  17. Type VII Collagen is Enriched in the Enamel Organic Matrix Associated with the Dentin-Enamel Junction of Mature Human Teeth

    OpenAIRE

    McGuire, Jacob D.; Walker, Mary P.; Mousa, Ahmad; Wang, Yong; Gorski, Jeff P.

    2014-01-01

    The inner enamel region of erupted teeth is known to exhibit higher fracture toughness and crack growth resistance than bulk phase enamel. However, an explanation for this behavior has been hampered by the lack of compositional information for the residual enamel organic matrix. Since enamel-forming ameloblasts are known to express type VII collagen and type VII collagen null mice display abnormal amelogenesis, the aim of this study was to determine whether type VII collagen is a component of...

  18. Determining the Effect of Calculus, Hypocalcification, and Stain on Using Optical Coherence Tomography and Polarized Raman Spectroscopy for Detecting White Spot Lesions

    Directory of Open Access Journals (Sweden)

    Amanda Huminicki

    2010-01-01

    Full Text Available Optical coherence tomography (OCT and polarized Raman spectroscopy (PRS have been shown as useful methods for distinguishing sound enamel from carious lesions ex vivo. However, factors in the oral environment such as calculus, hypocalcification, and stain could lead to false-positive results. OCT and PRS were used to investigate extracted human teeth clinically examined for sound enamel, white spot lesion (WSL, calculus, hypocalcification, and stain to determine whether these factors would confound WSL detection with these optical methods. Results indicate that OCT allowed differentiating caries from sound enamel, hypocalcification, and stain, with calculus deposits recognizable on OCT images. ANOVA and post-hoc unequal N HSD analyses to compare the mean Raman depolarization ratios from the various groups showed that the mean values were statistically significant at P<.05, except for several comparison pairs. With the current PRS analysis method, the mean depolarization ratios of stained enamel and caries are not significantly different due to the sloping background in the stained enamel spectra. Overall, calculus and hypocalcification are not confounding factors affecting WSL detection using OCT and PRS. Stain does not influence WSL detection with OCT. Improved PRS analysis methods are needed to differentiate carious from stained enamel.

  19. Microbial activity in the terrestrial subsurface

    International Nuclear Information System (INIS)

    Kaiser, J.P.; Bollag, J.M.

    1990-01-01

    Little is known about the layers under the earth's crust. Only in recent years have techniques for sampling the deeper subsurface been developed to permit investigation of the subsurface environment. Prevailing conditions in the subsurface habitat such as nutrient availability, soil composition, redox potential, permeability and a variety of other factors can influence the microflora that flourish in a given environment. Microbial diversity varies between geological formations, but in general sandy soils support growth better than soils rich in clay. Bacteria predominate in subsurface sediments, while eukaryotes constitute only 1-2% of the microorganisms. Recent investigations revealed that most uncontaminated subsurface soils support the growth of aerobic heteroorganotrophic bacteria, but obviously anaerobic microorganisms also exist in the deeper subsurface habitat. The microorganisms residing below the surface of the earth are capable of degrading both natural and xenobiotic contaminants and can thereby adapt to growth under polluted conditions. (author) 4 tabs, 77 refs

  20. Enamel hypoplasias and physiological stress in the Sima de los Huesos Middle Pleistocene hominins.

    Science.gov (United States)

    Cunha, E; Rozzi, F Ramirez; Bermúdez de Castro, J M; Martinón-Torres, M; Wasterlain, S N; Sarmiento, S

    2004-11-01

    This study presents an analysis of linear enamel hypoplasias (LEH) and plane-form defects (PFD) in the hominine dental sample from the Sima de los Huesos (SH) Middle Pleistocene site in Atapuerca (Spain). The SH sample comprises 475 teeth, 467 permanent and 8 deciduous, belonging to a minimum of 28 individuals. The method for recording PFD and LEH is discussed, as well as the definition of LEH. The prevalence of LEH and PFD in SH permanent dentition (unilateral total count) is 4.6% (13/280). Only one deciduous tooth (lower dc) showed an enamel disruption. Prevalence by individual ranges from 18.7-30%. The most likely explanation for the relatively low LEH and PFD prevalence in the SH sample suggests that the SH population exhibited a low level of developmental stress. The age at occurrence of LEH and PFD was determined by counting the number of perikymata between each lesion and the cervix of the tooth. Assuming a periodicity of nine days for the incremental lines, the majority of LEH in the SH sample occurred during the third year of life and may be related to the metabolic stress associated with weaning.

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

    Science.gov (United States)

    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

  2. Glass enamel and glass-ceramic coatings for chemical apparatus

    International Nuclear Information System (INIS)

    Es'kov, A.S.; Oleinik, M.I.; Shabrova, E.A.

    1984-01-01

    Among the known anticorrosion coatings used in chemical engineering, glass enamel base coatings are distinguished by such advantages as a high degree of continuity and chemical resistance. The paper describes basic principles for the creation of acid and alkali resistant glass enamel and ceramic coatings for chemical apparatus. As the result of investgations, glass enamel coatings with increased electrical conductivity and also experimental production compositions of chemical, temperature and radiation resistant coatings for protection of chemical equipment of 12Kh18N10T stainless steel have been developed. The coatings have successfully passed testing under service conditions. A new type of coating is short-term glass enamel, which may be recommended for use in chemical machinery manufacturing and other branches of industry in oxidation-free heating and forming of stainless steels

  3. Abrasive wear of enamel by bioactive glass-based toothpastes.

    Science.gov (United States)

    Mahmood, Asad; Mneimne, Mohammed; Zou, Li Fong; Hill, Robert G; Gillam, David G

    2014-10-01

    To determine the abrasivity of a 45S5 bioactive glass based toothpaste on enamel as a function of the particle size and shape of the glass. 45S5 glass was synthesized ground and sieved to give various particle sized fractions toothpastes and their tooth brush abrasivity measured according to BS EN ISO11609 methodology. Enamel loss increased with increasing particle size. The percussion milled powder exhibited particles that had sharp edges and the pastes were significantly more abrasive than the pastes made with round ball milled powders. One interesting observation made during the present study was that there was preferential wear of the enamel at the dentin-enamel junction (DEJ), particularly with the coarse particle sized pastes.

  4. Geographic Variations in the EPR Spectrum of Tooth Enamel

    International Nuclear Information System (INIS)

    Romanyukha, A.A.; Hayes, R.B.; Haskell, E.H.; Kenner, G.H.

    1999-01-01

    The presence of stable radiation-induced radicals in the mineral component of tooth enamel allows use of this material as a biological dosemeter. Estimation of the dose absorbed in tooth enamel can be done by EPR. Generally, for the purpose of dose reconstruction, the EPR spectrum of tooth enamel is interpreted in terms of two main components. The first is a broad background signal often called the native signal centered at a g value of 2.0045. The origin of this signal is not precisely known. The second main component in the tooth enamel spectrum is purely radiation induced and can be used for retrospective dosimetry. Internal structure of the native signal and variations of its amplitude and linewidth were investigated for the samples prepared from modern teeth obtained from different geographic locations (USA and Russia). Possible reasons for the variations observed are discussed as are the potential effects of the variations on the reliability of dose estimation. (author)

  5. Protection of enamel surfaces in the oral cavity

    DEFF Research Database (Denmark)

    Lazovic, Maja Bruvo

    The two main diseases that can affect the tooth enamel are dental caries and dental erosion, which both are caused by exposure of the enamel surfaces to acids. In the case of dental caries, acids from bacterial metabolism cause chemical dissolution of the tooth surface, whereas acids from drinks...... and foodstuffs or gastric juice can cause dental erosion. During a lifetime the enamel surface is also exposed to fluids that can have protective effects against dental caries and erosion such as saliva, various foodstuffs, drinking water and many types of drinks. However, little is still known about simple...... inorganic interactions between different fluids and dental caries and little is also known about which saliva proteins are able to protect the enamel surface against dental erosion. Therefore, the overall aim of this thesis was to examine simple inorganic and protein related protective effects with dental...

  6. In phantom dosimetric response of tooth enamel to neutrons

    International Nuclear Information System (INIS)

    Fattibene, P.; Angelone, M.; Pillon, M.; De Coste, V.

    2004-01-01

    Electron Paramagnetic Resonance dosimetry based on tooth enamel has one important application in dose reconstruction of nuclear plant workers, where the contribution of neutrons to individual dose is often important. Evaluation of tooth enamel response to neutrons is thus an important goal. A few experimental data at thermal and fast neutron energies are available. A first evaluation of the tooth enamel relative response to 60 Co in monoenergetic neutron flux of 2.8 and of 14 MeV, published elsewhere, has provided results apparently non-consistent with the results obtained at lower and higher energies. A comparison of those results in the 2.8 and 14 MeV beams with those available in the literature for other beams is reported and possible reasons for incongruities are discussed. Dose conversion factors of enamel to the water and air are also calculated and reported. (authors)

  7. Femtosecond laser etching of dental enamel for bracket bonding.

    Science.gov (United States)

    Kabas, Ayse Sena; Ersoy, Tansu; Gülsoy, Murat; Akturk, Selcuk

    2013-09-01

    The aim is to investigate femtosecond laser ablation as an alternative method for enamel etching used before bonding orthodontic brackets. A focused laser beam is scanned over enamel within the area of bonding in a saw tooth pattern with a varying number of lines. After patterning, ceramic brackets are bonded and bonding quality of the proposed technique is measured by a universal testing machine. The results are compared to the conventional acid etching method. Results show that bonding strength is a function of laser average power and the density of the ablated lines. Intrapulpal temperature changes are also recorded and observed minimal effects are observed. Enamel surface of the samples is investigated microscopically and no signs of damage or cracking are observed. In conclusion, femtosecond laser exposure on enamel surface yields controllable patterns that provide efficient bonding strength with less removal of dental tissue than conventional acid-etching technique.

  8. Large scale study of tooth enamel

    International Nuclear Information System (INIS)

    Bodart, F.; Deconninck, G.; Martin, M.T.

    Human tooth enamel contains traces of foreign elements. The presence of these elements is related to the history and the environment of the human body and can be considered as the signature of perturbations which occur during the growth of a tooth. A map of the distribution of these traces on a large scale sample of the population will constitute a reference for further investigations of environmental effects. On hundred eighty samples of teeth were first analyzed using PIXE, backscattering and nuclear reaction techniques. The results were analyzed using statistical methods. Correlations between O, F, Na, P, Ca, Mn, Fe, Cu, Zn, Pb and Sr were observed and cluster analysis was in progress. The techniques described in the present work have been developed in order to establish a method for the exploration of very large samples of the Belgian population. (author)

  9. Relationship between enamel bond fatigue durability and surface free-energy characteristics with universal adhesives.

    Science.gov (United States)

    Nagura, Yuko; Tsujimoto, Akimasa; Barkmeier, Wayne W; Watanabe, Hidehiko; Johnson, William W; Takamizawa, Toshiki; Latta, Mark A; Miyazaki, Masashi

    2018-04-01

    The relationship between enamel bond fatigue durability and surface free-energy characteristics with universal adhesives was investigated. The initial shear bond strengths and shear fatigue strengths of five universal adhesives to enamel were determined with and without phosphoric acid pre-etching. The surface free-energy characteristics of adhesive-treated enamel with and without pre-etching were also determined. The initial shear bond strength and shear fatigue strength of universal adhesive to pre-etched enamel were higher than those to ground enamel. The initial shear bond strength and shear fatigue strength of universal adhesive to pre-etched enamel were material dependent, unlike those to ground enamel. The surface free-energy of the solid (γ S ) and the hydrogen-bonding force (γSh) of universal adhesive-treated enamel were different depending on the adhesive, regardless of the presence or absence of pre-etching. The bond fatigue durability of universal adhesives was higher to pre-etched enamel than to ground enamel. In addition, the bond fatigue durability to pre-etched enamel was material dependent, unlike that to ground enamel. The surface free-energy characteristics of universal adhesive-treated enamel were influenced by the adhesive type, regardless of the presence or absence of pre-etching. The surface free-energy characteristics of universal adhesive-treated enamel were related to the results of the bond fatigue durability. © 2018 Eur J Oral Sci.

  10. Analysis of enamel development using murine model systems: approaches and limitations.

    Directory of Open Access Journals (Sweden)

    Megan K Pugach

    2014-09-01

    Full Text Available A primary goal of enamel research is to understand and potentially treat or prevent enamel defects related to amelogenesis imperfecta (AI. Rodents are ideal models to assist our understanding of how enamel is formed because they are easily genetically modified, and their continuously erupting incisors display all stages of enamel development and mineralization. While numerous methods have been developed to generate and analyze genetically modified rodent enamel, it is crucial to understand the limitations and challenges associated with these methods in order to draw appropriate conclusions that can be applied translationally, to AI patient care. We have highlighted methods involved in generating and analyzing rodent enamel and potential approaches to overcoming limitations of these methods: 1 generating transgenic, knockout and knockin mouse models, and 2 analyzing rodent enamel mineral density and functional properties (structure, mechanics of mature enamel. There is a need for a standardized workflow to analyze enamel phenotypes in rodent models so that investigators can compare data from different studies. These methods include analyses of gene and protein expression, developing enamel histology, enamel pigment, degree of mineralization, enamel structure and mechanical properties. Standardization of these methods with regard to stage of enamel development and sample preparation is crucial, and ideally investigators can use correlative and complementary techniques with the understanding that developing mouse enamel is dynamic and complex.

  11. Microabrasion as treatment of enamel fluorosis

    Directory of Open Access Journals (Sweden)

    Ana Caroline Brito

    2008-01-01

    Full Text Available There is currently a trend in favor of using fluoride as a coadjuvant in reducing caries indexes, as much in underdeveloped as in developedcountries. However, simultaneously the indexes of dental fluorosis seem to grow in an inverse proportion. This is brought about by chronic ingestion of fluoride for a prolonged length of time or in high concentration. Enamel microabrasion is an effective method to remove superficial stains caused by this condition, which affects esthetics of that tissue. The use of 18% hydrochloric acid in association with pumice, despite being a simple and low cost method, has been gradually replaced due to its potential of causing damage to periodontal tissues. Thus, this article reports the treatment of a fluorosis clinical case solved with microabrasion using phosphoric acid 37%, because its costbenefit is supposedly better than with chloridric acid. The deliberate ingestion of toothpaste was the probable cause of the tooth stains. Due to the location of the teeth and to the patient’s smile, only the six upper anterior teeth were selected to receive the proposed treatment. Four clinical sessions, with a seven days interval between each other, were carried out using 37% phosphoric acid and pumice. Under rubber dam isolation, the two first sessions consisted of rubbing the acid-pumice mix on enamel surface using a rubber cup on slow speed, and abrasive paper strips on the interproximal tooth surfaces. On the two final sessions, only finishing touches were performed using a wooden spatula to manually rub the acid-pumice paste.

  12. Influence of Surfactants and Fluoride against Enamel Erosion.

    Science.gov (United States)

    Zanatta, Rayssa Ferreira; Ávila, Daniele Mara da Silva; Miyamoto, Karen Mayumi; Torres, Carlos Rocha Gomes; Borges, Alessandra Bühler

    2018-06-06

    This study investigated the effect of surfactants associated with sodium fluoride (NaF) on enamel erosion prevention, using an erosion-remineralization in vitro model. Sodium lauryl sulfate (SLS), polysorbate 20 (P20), and cocoamidopropyl betaine (CAPB) were tested, at concentrations of 1.0 and 1.5%, and associated or not with NaF (275 ppm). The control groups were distilled water and the NaF solution. Bovine enamel samples (n = 12) were prepared and submitted to a 5-day cycling model: acid challenge (0.3% citric acid, pH 2.6, 4×/day), human saliva (2 h, 4×/day), and the treatment solutions (2 min, 2×/day). The protective potential of the agents against initial erosion was assessed by microhardness and the surface loss by profilometry. Enamel surface wettability was determined by goniometry, protein adsorption was measured by spectroscopy (FTIR), and the KOH-soluble fluoride was quantified. Goniometry showed that SLS and CAPB increased enamel wettability. No differences were found among the surfactants regarding protein adsorption. Microhardness showed that SLS reduced NaF protection. P20 (1 and 1.5%) and CAPB 1.5% presented a protective effect, but lower than the NaF solution. Profilometry showed that CAPB protected enamel, but no agent associated with NaF promoted a higher protection than the NaF solution alone. KOH-soluble fluoride analysis showed that all surfactants reduced the fluoride adsorption on the enamel surface. Therefore, the surfactants tested (except for P20) changed the enamel surface energy. The SLS decreased the protective potential of NaF on initial erosion, but no tested agent interfered with the protective effect of NaF on enamel erosive wear. © 2018 S. Karger AG, Basel.

  13. Enamel: From brittle to ductile like tribological response.

    Science.gov (United States)

    Guidoni, G; Swain, M; Jäger, I

    2008-10-01

    To identify the intrinsic nano-scale wear mechanisms of enamel by comparing it with that of highly brittle glass, and highly ductile copper and silver monocrystals. A sharp cube corner indenter tip (20-50 nm radius) was used to abrade glass, enamel as well as copper and silver monocrystals. Square abraded areas (5 microm x 5 microm, 10 microm x 10 microm) were generated with loads of 50 microN for enamel and 100 microN for the remaining materials (2D abrasion). The normal load and displacement data were utilized in a complementary manner to support the comparison. In addition normal and lateral forces were simultaneously measured along 10 microm single scratched lines (1D abrasion). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were also used to characterise the worn areas and debris. The sharp tip cuts into and ploughs the specimens creating a wedge or ridge of material ahead of itself which eventually detaches, for the ductile materials and at high loads in enamel. For glass and enamel at low loads, the indenter tip ploughs into the material and the removed material is redistributed and pressed back into the abraded area. The wear behaviour of enamel at the nano-level resembles that obtained with glass at low loads (50 microN) and that obtained with metal mono-crystals at high load (100 microN). The role of the microstructural heterogeneity in the wear behaviour of enamel is considered in the discussion. The relevance to clinical wear of enamel is also considered.

  14. DENTAL ENAMEL FORMATION AND IMPLICATIONS FOR ORAL HEALTH AND DISEASE.

    Science.gov (United States)

    Lacruz, Rodrigo S; Habelitz, Stefan; Wright, J Timothy; Paine, Michael L

    2017-07-01

    Dental enamel is the hardest and most mineralized tissue in extinct and extant vertebrate species and provides maximum durability that allows teeth to function as weapons and/or tools as well as for food processing. Enamel development and mineralization is an intricate process tightly regulated by cells of the enamel organ called ameloblasts. These heavily polarized cells form a monolayer around the developing enamel tissue and move as a single forming front in specified directions as they lay down a proteinaceous matrix that serves as a template for crystal growth. Ameloblasts maintain intercellular connections creating a semi-permeable barrier that at one end (basal/proximal) receives nutrients and ions from blood vessels, and at the opposite end (secretory/apical/distal) forms extracellular crystals within specified pH conditions. In this unique environment, ameloblasts orchestrate crystal growth via multiple cellular activities including modulating the transport of minerals and ions, pH regulation, proteolysis, and endocytosis. In many vertebrates, the bulk of the enamel tissue volume is first formed and subsequently mineralized by these same cells as they retransform their morphology and function. Cell death by apoptosis and regression are the fates of many ameloblasts following enamel maturation, and what cells remain of the enamel organ are shed during tooth eruption, or are incorporated into the tooth's epithelial attachment to the oral gingiva. In this review, we examine key aspects of dental enamel formation, from its developmental genesis to the ever-increasing wealth of data on the mechanisms mediating ionic transport, as well as the clinical outcomes resulting from abnormal ameloblast function. Copyright © 2017 the American Physiological Society.

  15. Indirect veneer treatment of anterior maxillary teeth with enamel hypoplasia

    OpenAIRE

    Juniarti, Devi Eka

    2010-01-01

    Background: Nowadays, aesthetic rehabilitation becomes a necessity. It is affected by patient’s background, especially career, social and economic status. The aesthetic abnormality of anterior teeth i.e discoloration, malposition and malformation can affect patient’s appearance, especially during smile. These dental abnormalities, as a result, can decrease patient’s performance. Dental malformation, for instance, can be caused by developmental tooth defect, such as enamel hypoplasia. Enamel h...

  16. Refining enamel thickness measurements from B-mode ultrasound images.

    Science.gov (United States)

    Hua, Jeremy; Chen, Ssu-Kuang; Kim, Yongmin

    2009-01-01

    Dental erosion has been growing increasingly prevalent with the rise in consumption of heavy starches, sugars, coffee, and acidic beverages. In addition, various disorders, such as Gastroenterological Reflux Disease (GERD), have symptoms of rapid rates of tooth erosion. The measurement of enamel thickness would be important for dentists to assess the progression of enamel loss from all forms of erosion, attrition, and abrasion. Characterizing enamel loss is currently done with various subjective indexes that can be interpreted in different ways by different dentists. Ultrasound has been utilized since the 1960s to determine internal tooth structure, but with mixed results. Via image processing and enhancement, we were able to refine B-mode dental ultrasound images for more accurate enamel thickness measurements. The mean difference between the measured thickness of the occlusal enamel from ultrasound images and corresponding gold standard CT images improved from 0.55 mm to 0.32 mm with image processing (p = 0.033). The difference also improved from 0.62 to 0.53 mm at the buccal/lingual enamel surfaces, but not significantly (p = 0.38).

  17. Separate whitening effects on enamel and dentin after fourteen days.

    Science.gov (United States)

    Kugel, Gerard; Petkevis, Jason; Gurgan, Sevil; Doherty, Eileen

    2007-01-01

    The purpose of this study was to investigate the mechanism of action of a bleaching agent, as it relates to enamel and dentin. Twenty-six extracted human molar teeth were sectioned at the cemento-enamel junction and were randomly assigned to two groups. L*a*b* readings were taken with a spectrophotometer: on buccal surfaces of the crown, at enamel and dentin. The teeth were exposed to carbamide peroxide or placebo gel and L*a*b* scores were again recorded to determine color changes. Treatments were compared using ancova test with baseline color as the covariate. Relative to placebo, buccal surfaces exhibited the greatest Deltab* and DeltaL* color change. On buccal surfaces, the adjusted mean (SE) treatment differences were -7.8 (1.00) for Deltab* and 5.7 (0.97) for DeltaL, with groups differing significantly (p enamel surfaces, treatment differences were -3.6 (0.61) for Deltab* and 4.6 (0.80) for DeltaL* (p tooth crowns exposed to carbamide peroxide 15% was because of the color change in enamel. As compared to enamel, dentin was less affected after 14 days.

  18. Anisotropic properties of the enamel organic extracellular matrix.

    Science.gov (United States)

    do Espírito Santo, Alexandre R; Novaes, Pedro D; Line, Sérgio R P

    2006-05-01

    Enamel biosynthesis is initiated by the secretion, processing, and self-assembly of a complex mixture of proteins. This supramolecular ensemble controls the nucleation of the crystalline mineral phase. The detection of anisotropic properties by polarizing microscopy has been extensively used to detect macromolecular organizations in ordinary histological sections. The aim of this work was to study the birefringence of enamel organic matrix during the development of rat molar and incisor teeth. Incisor and molar teeth of rats were fixed in 2% paraformaldehyde/0.5% glutaraldehyde in 0.2 M phosphate-buffered saline (PBS), pH 7.2, and decalcified in 5% nitric acid/4% formaldehyde. After paraffin embedding, 5-microm-thick sections were obtained, treated with xylene, and hydrated. Form birefringence curves were obtained after measuring optical retardations in imbibing media, with different refractive indices. Our observations showed that enamel organic matrix of rat incisor and molar teeth is strongly birefringent, presenting an ordered supramolecular structure. The birefringence starts during the early secretion phase and disappears at the maturation phase. The analysis of enamel organic matrix birefringence may be used to detect the effects of genetic and environmental factors on the supramolecular orientation of enamel matrix and their effects on the structure of mature enamel.

  19. Theobromine Effects on Enamel Surface Microhardness: In Vitro

    Directory of Open Access Journals (Sweden)

    Grace Syafira

    2013-07-01

    Full Text Available Dental caries is still a dental health problem in Indonesia. Fluoride, one of the dental caries prevention material, but its safety and the danger of fluorosis is still debated. Theobromine is an alkaloid compound contained in cocoa beans. Theobromine is believed to increase enamel microhardness with mineral changes in the enamel superficial layer. Objectives: To determine the influence of theobromine on the enamel surface microhardness. Methods: This study used 40 premolar tooth crown pieces that were embedded in epoxy resin. Furthermore specimens were randomly divided into 4 groups, which were control (distilled water, theobromine 100 mg/L (T100, theobromine 500 mg/L (T500 and theobromine 1000 mg/L (T1000. Specimens were immersed for 15 minutes and microhardness test was performed using Knoop microhardness tester. Results: Increasing enamel microhardness was observed after treatment with four different theobromine concentrations. The highest icreased of enamel microhardness was shown in T1000 group and difference compared to other groups were statistically significant (p<0.05. Conclusion: theobromine is a potential dental caries prevention material due to its effect in improving the microhardness of tooth enamel.

  20. Ca2+ transport and signalling in enamel cells

    Science.gov (United States)

    Nurbaeva, Meerim K.; Eckstein, Miriam; Feske, Stefan

    2016-01-01

    Abstract Dental enamel is one of the most remarkable examples of matrix‐mediated biomineralization. Enamel crystals form de novo in a rich extracellular environment in a stage‐dependent manner producing complex microstructural patterns that are visually stunning. This process is orchestrated by specialized epithelial cells known as ameloblasts which themselves undergo striking morphological changes, switching function from a secretory role to a cell primarily engaged in ionic transport. Ameloblasts are supported by a host of cell types which combined represent the enamel organ. Fully mineralized enamel is the hardest tissue found in vertebrates owing its properties partly to the unique mixture of ionic species represented and their highly organized assembly in the crystal lattice. Among the main elements found in enamel, Ca2+ is the most abundant ion, yet how ameloblasts modulate Ca2+ dynamics remains poorly known. This review describes previously proposed models for passive and active Ca2+ transport, the intracellular Ca2+ buffering systems expressed in ameloblasts and provides an up‐dated view of current models concerning Ca2+ influx and extrusion mechanisms, where most of the recent advances have been made. We also advance a new model for Ca2+ transport by the enamel organ. PMID:27510811

  1. Enamel dose calculation by electron paramagnetic resonance spectral simulation technique

    International Nuclear Information System (INIS)

    Dong Guofu; Cong Jianbo; Guo Linchao; Ning Jing; Xian Hong; Wang Changzhen; Wu Ke

    2011-01-01

    Objective: To optimize the enamel electron paramagnetic resonance (EPR) spectral processing by using the EPR spectral simulation method to improve the accuracy of enamel EPR dosimetry and reduce artificial error. Methods: The multi-component superimposed EPR powder spectral simulation software was developed to simulate EPR spectrum models of the background signal (BS) and the radiation- induced signal (RS) of irradiated enamel respectively. RS was extracted from the multi-component superimposed spectrum of irradiated enamel and its amplitude was calculated. The dose-response curve was then established for calculating the doses of a group of enamel samples. The result of estimated dose was compared with that calculated by traditional method. Results: BS was simulated as a powder spectrum of gaussian line shape with the following spectrum parameters: g=2.00 35 and Hpp=0.65-1.1 mT, RS signal was also simulated as a powder spectrum but with axi-symmetric spectrum characteristics. The spectrum parameters of RS were: g ⊥ =2.0018, g ‖ =1.9965, Hpp=0.335-0.4 mT. The amplitude of RS had a linear response to radiation dose with the regression equation as y=240.74x + 76 724 (R 2 =0.9947). The expectation of relative error of dose estimation was 0.13. Conclusions: EPR simulation method has improved somehow the accuracy and reliability of enamel EPR dose estimation. (authors)

  2. Enamel and dentin bond strength following gaseous ozone application.

    Science.gov (United States)

    Cadenaro, Milena; Delise, Chiara; Antoniollo, Francesca; Navarra, Ottavia Chiara; Di Lenarda, Roberto; Breschi, Lorenzo

    2009-08-01

    To evaluate the effects of gaseous ozone application on enamel and dentin bond strength produced by two self-etching adhesive systems. The shear bond strength test was conducted to assess adhesion on enamel (protocol 1), while the microtensile bond strength test was performed on dentin (protocol 2). Protocol 1: 96 bovine incisors were randomly divided into 4 groups, and enamel surfaces were bonded in accordance with the following treatments: (1E) ozone + Clearfil Protect Bond; (2E) Clearfil Protect Bond (control); (3E) ozone + Xeno III; (4E) Xeno III (control). Ozone gas was applied for 80 s. Shear bond strength was measured with a universal testing machine. Protocol 2: 40 noncarious human molars were selected. Middle/deep dentin was exposed and bonded in accordance with the following treatments: (1D) ozone+Clearfil Protect Bond; (2D) Clearfil Protect Bond (control); (3D) ozone+Xeno III (4D) Xeno III (control). Four-mm-thick buildups were built on the adhesives, then specimens were sectioned in accordance with the nontrimming technique. Specimens were stressed until failure occurred, and failure modes were analyzed. Shear bond and microtensile bond strength data were analyzed using two-way ANOVA and Tukey's post-hoc test. No statistical differences were found between ozone treated specimens and controls, neither on enamel nor on dentin irrespective of the tested adhesive. Clearfil Protect Bond showed higher bond strength to enamel than Xeno III, irrespective of the ozone treatment (p enamel and dentin bond strength.

  3. Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

    Science.gov (United States)

    Yasuhiro, Matsuda; Katsushi, Okuyama; Hiroko, Yamamoto; Hisanori, Komatsu; Masashi, Koka; Takahiro, Sato; Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano

    2015-04-01

    To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials ["MS coats F" (MSF)] and fluoride-free sealing materials ("hybrid coats 2" [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8-4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries.

  4. Metabolism in tooth enamel and reliability of retrospective EPR dosimetry connected with Chernobyl accident

    International Nuclear Information System (INIS)

    Brik, A.; Radchuk, V.; Scherbina, O.; Matyash, M.; Gaver, O.

    1996-01-01

    It is shown that the results of retrospective EPR dosimetry by tooth enamel are essentially determined by the fact that tooth enamel is the mineral of biological origin. The structure of tooth enamel, properties of radiation defects and the role of metabolism in tooth enamel are discussed. It is shown that at deep metamorphic modifications tooth enamel don't save information about its radiation history. The reliability and accuracy of retrospective EPR dosimetry are discussed. Because after Chernobyl accident have passed 10 years the application of tooth enamel for reconstruction of doses which are connected with Chernobyl accident need care and additional investigations

  5. [Differential diagnosis of dental enamel focal demineralization and fluorosis by means of spectrophotometry].

    Science.gov (United States)

    Makarova, N E; Vinnichenko, Yu A

    2018-01-01

    The article presents the results of spectrophotometric tooth enamel scanning for differential diagnosis of focal enamel demineralization and fluorosis. Research was conducted in vivo on teeth affected by these diseases. VITA EasyShade spectrophotometer measurements were made on the affected area and on the visually healthy part of enamel. The lightness appeared as the only one differential significant optical characteristics of tooth enamel. Lightness metrics were higher in the case of initial caries than on the healthy part of enamel when these metrics were lower in the case of fluorosis than on the healthy part of enamel.

  6. Indirect veneer treatment of anterior maxillary teeth with enamel hypoplasia

    Directory of Open Access Journals (Sweden)

    Devi Eka Juniarti

    2010-09-01

    Full Text Available Background: Nowadays, aesthetic rehabilitation becomes a necessity. It is affected by patient’s background, especially career, social and economic status. The aesthetic abnormality of anterior teeth i.e discoloration, malposition and malformation can affect patient’s appearance, especially during smile. These dental abnormalities, as a result, can decrease patient’s performance. Dental malformation, for instance, can be caused by developmental tooth defect, such as enamel hypoplasia. Enamel hypoplasia is a developmental defect caused by the lack of matrix amount which leads to thin and porous enamel. Enamel hypoplasia can also be caused by matrix calcification disturbance starting from the formation and development of enamel matrix causing defect and permanent changes which can occur on one or more tooth. Purpose: The aim of the study is to improve dental discoloration and tooth surface texture on anterior maxillary teeth with enamel hypoplasia by using indirect veneer with porcelain material. Case: A 20 years-old woman with enamel hypoplasia came to the Dental Hospital, Faculty of Dentistry Airlangga University. The patient wanted to improve her anterior maxillary teeth. It is clinically known that there were some opaque white spots (chalky spotted and porous on anterior teeth’s surface. Case management: Indirect veneer with porcelain material had been chosen as a restoration treatment which has excellent aesthetics and strength, and did not cause gingival irritation. As a result, the treatment could improve the confidence of the patient, and could also make their function normal. Conclusion: Indirect veneer is an effective treatment, which can improve patient’s appearance and self confidence.Latar belakang: Saat ini perbaikan estetik menjadi suatu kebutuhan. Kebutuhan akan estetik dipengaruhi latar belakang penderita, terutama karir, status sosial dan ekonomi. Hal ini disebabkan, kelainan estetik seperti diskolorasi, malposisi

  7. Cultivating the Deep Subsurface Microbiome

    Science.gov (United States)

    Casar, C. P.; Osburn, M. R.; Flynn, T. M.; Masterson, A.; Kruger, B.

    2017-12-01

    Subterranean ecosystems are poorly understood because many microbes detected in metagenomic surveys are only distantly related to characterized isolates. Cultivating microorganisms from the deep subsurface is challenging due to its inaccessibility and potential for contamination. The Deep Mine Microbial Observatory (DeMMO) in Lead, SD however, offers access to deep microbial life via pristine fracture fluids in bedrock to a depth of 1478 m. The metabolic landscape of DeMMO was previously characterized via thermodynamic modeling coupled with genomic data, illustrating the potential for microbial inhabitants of DeMMO to utilize mineral substrates as energy sources. Here, we employ field and lab based cultivation approaches with pure minerals to link phylogeny to metabolism at DeMMO. Fracture fluids were directed through reactors filled with Fe3O4, Fe2O3, FeS2, MnO2, and FeCO3 at two sites (610 m and 1478 m) for 2 months prior to harvesting for subsequent analyses. We examined mineralogical, geochemical, and microbiological composition of the reactors via DNA sequencing, microscopy, lipid biomarker characterization, and bulk C and N isotope ratios to determine the influence of mineralogy on biofilm community development. Pre-characterized mineral chips were imaged via SEM to assay microbial growth; preliminary results suggest MnO2, Fe3O4, and Fe2O3 were most conducive to colonization. Solid materials from reactors were used as inoculum for batch cultivation experiments. Media designed to mimic fracture fluid chemistry was supplemented with mineral substrates targeting metal reducers. DNA sequences and microscopy of iron oxide-rich biofilms and fracture fluids suggest iron oxidation is a major energy source at redox transition zones where anaerobic fluids meet more oxidizing conditions. We utilized these biofilms and fluids as inoculum in gradient cultivation experiments targeting microaerophilic iron oxidizers. Cultivation of microbes endemic to DeMMO, a system

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

    Science.gov (United States)

    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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Wear of human enamel: a quantitative in vitro assessment.

    Science.gov (United States)

    Kaidonis, J A; Richards, L C; Townsend, G C; Tansley, G D

    1998-12-01

    Many factors influence the extent and rate at which enamel wears. Clinical studies in humans are limited by difficulties in the accurate quantification of intra-oral wear and by a lack of control over the oral environment. The purpose of this study was to determine the wear characteristics of human dental enamel under controlled experimental conditions. An electro-mechanical tooth wear machine, in which opposing enamel surfaces of sectioned, extracted teeth were worn under various conditions, was used to simulate tooth grinding or bruxism. Enamel surface wear was quantified by weight to an accuracy of 0.1 mg, with water uptake and loss controlled. The variables considered included the structure and hardness of enamel, facet area, duration of tooth contact, relative speed of opposing surfaces, temperature, load, pH, and the nature of the lubricant. Enamel wear under non-lubricated conditions increased with increasing load over the range of 1.7 to 16.2 kg. The addition of a liquid lubricant (pH = 7) reduced enamel wear up to 6.7 kg, but when the load increased above this threshold, the rate of wear increased dramatically. With the viscosity of the lubricant constant and pH = 3, the rate of wear was further reduced to less than 10% of the non-lubricated rate at 9.95 kg, after which the rate again increased substantially. Under more extreme conditions (pH = 1.2, simulating gastric acids), the wear was excessive under all experimental loads. When saliva was used as a lubricant, the amount of wear was relatively low at 9.95 kg, but rapid wear occurred at 14.2 kg and above. These results indicate that under non-lubricated conditions, enamel wear remains low at high loads due to the dry-lubricating capabilities of fine enamel powder. Under lubricated conditions, low loads with an acidic lubricant lead to little enamel wear, whereas very low pH results in a high rate of wear under all loads.

  10. Drawing the subsurface : an integrative design approach

    NARCIS (Netherlands)

    Hooimeijer, F.L.; Lafleur, F.; Trinh, T.T.; Gogu, Constantin Radu; Campbell, Diarmad; de Beer, Johannes

    2017-01-01

    The sub-surface, with its man-made and natural components, plays an important, if not crucial, role in the urban climate and global energy transition. On the one hand, the sub-surface is associated with a variety of challenges such as subsidence, pollution, damage to infrastructure and shortages of

  11. Extracting subsurface fingerprints using optical coherence tomography

    CSIR Research Space (South Africa)

    Akhoury, SS

    2015-02-01

    Full Text Available Subsurface Fingerprints using Optical Coherence Tomography Sharat Saurabh Akhoury, Luke Nicholas Darlow Modelling and Digital Science, Council for Scientific and Industrial Research, Pretoria, South Africa Abstract Physiologists have found... approach to extract the subsurface fingerprint representation using a high-resolution imaging technology known as Optical Coherence Tomography (OCT). ...

  12. Innovative Approaches to Regenerate Enamel and Dentin

    Directory of Open Access Journals (Sweden)

    Xanthippi Chatzistavrou

    2012-01-01

    Full Text Available The process of tooth mineralization and the role of molecular control of cellular behavior during embryonic tooth development have attracted much attention the last few years. The knowledge gained from the research in these fields has improved the general understanding about the formation of dental tissues and the entire tooth and set the basis for teeth regeneration. Tissue engineering using scaffold and cell aggregate methods has been considered to produce bioengineered dental tissues, while dental stem/progenitor cells, which can differentiate into dental cell lineages, have been also introduced into the field of tooth mineralization and regeneration. Some of the main strategies for making enamel, dentin, and complex tooth-like structures are presented in this paper. However, there are still significant barriers that obstruct such strategies to move into the regular clinic practice, and these should be overcome in order to have the regenerative dentistry as the important mean that can treat the consequences of tooth-related diseases.

  13. Bonding strategies for MIH-affected enamel and dentin.

    Science.gov (United States)

    Krämer, Norbert; Bui Khac, Ngoc-Han Nana; Lücker, Susanne; Stachniss, Vitus; Frankenberger, Roland

    2018-02-01

    Aim of the present study was to evaluate resin composite adhesion to dental hard tissues affected by molar incisor hypomineralisation (MIH). 94 freshly extracted human molars and incisors (53 suffering MIH) were used. 68 teeth (35 with MIH) were used for μ-TBS tests in enamel and dentin, 26 (18 with MIH) for qualitative evaluation. Specimens were bonded with Clearfil SE Bond, Scotchbond Universal, and OptiBond FL. For MIH affected enamel, additional OptiBond FL groups with NaOCl and NaOCl+Icon were investigated. Beside fractographic analysis, also qualitative evaluations were performed using SEM at different magnifications as well as histological sectioning. Highest μ-TBS values were recorded with dentin specimens (ANOVA, mod. LSD, p0.05). Pre-test failures did not occur in dentin specimens. Sound enamel specimens exhibited significantly higher μ-TBS values than MIH enamel (p0.05), however, it caused less pre-test failures (pMIH enamel is the limiting factor in adhesion to MIH teeth. MIH-affected dentin may be bonded conventionally. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

  15. EFFECT OF SURFACE CONDTIONINGON BOND STRENGTH TO ENAMEL AND DENTIN

    Directory of Open Access Journals (Sweden)

    M MOUSAVINASAB

    2002-09-01

    Full Text Available Introduction. Compoglass is a trade mark of dental compomers and because of its partially resinus structure, surface conditioning of dental surfaces is needed for a better bonding process. In this study, the effect of enamel and dentin conditioning procedure on shear bond strength (SBS of compoglass to tooth surfaces was studied. Methods. four groups each one including 11 sound premolars were chosen and their surfaces were prepared as following groups: group1, unconitioned dentin; group 2, dentin conditioning with phosphoric acid 35%; group 3, dentin conditioning with polyacrylic acid 20% group 4, unconditioning enamel; group 5, enamel conditioning with phosphoric acid 35%; and group 6, enamel conditioning with polyacrylic acid 20%. Compoglass was bonded to prepared surfaces and after fixation of the samples in acrylic molds, all samples were tested under shear force of instron testing machine at a rate of 1 mm/min speed. Results. The mean SBS obtained in these 6 groups were 6.207, 8.057, 10.146, 25.939 and 11.827 mpa. the mode of fracture also studied using a streomicroscope. Statistical analysis of the results showed that the maximum SBS obtained in group 5 and the lowest SBS about 6.207 mpa obtained in group 1. Despite increase in SBS group 2 and 3, there was no statistical differncies between group 1, 2 and 3. Discussion. Based on results of this study, conditioning of enamel and dentin surface due to improve SBS is recommeneded.

  16. Enzyme replacement prevents enamel defects in hypophosphatasia mice

    Science.gov (United States)

    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

    2012-01-01

    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−/−, a.k.a. 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 (sALP-FcD10, a.k.a. ENB-0040) 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

  17. Solubility and diffusivity of hydrogen in enameling steel

    Energy Technology Data Exchange (ETDEWEB)

    De Gregorio, P.; Valentini, R.; Solina, A.; Gastaldo, F. (Centro Sviluppo Materiali, Rome (Italy) Pisa Univ. (Italy). Dip. di Ingegneria Chimica, Chimica Industriale e Scienza dei Materiali)

    1991-06-01

    In recent years, continuous casting has almost expelled conventional ingot casting from the steel-making process by its much higher productivity. However, enameling steel sheets doesn't give the steel sufficient resistance to fishscale, as that which is achieved by the inclusions in case of ingot capped steel. Fishscales are caused by hydrogen gas building up pressure at the interface between enamel and steel, resulting in the rupture of enamel. Object of this study, was not only to correlate fishscale susceptibility with metallurgical parameters, but to define the effect of reversible and irreversible traps on hydrogen solubility and diffusivity in enameling steel. Hydrogen permeation was studied, in low carbon enameling steel, with an electrochemical technique developed by Devanathan and co-workers. This method was used to calculate concentrations of irreversibly adsorbed hydrogen and evaluate hydrogen diffusion coefficients. The results on reversible traps correlated with micro-voids formations around the carbide precipitate, while the irreversible traps correlated with inclusions and precipitate content.

  18. Enamel formation and growth in non-mammalian cynodonts

    Science.gov (United States)

    Dirks, Wendy; Martinelli, Agustín G.

    2018-01-01

    The early evolution of mammals is associated with the linked evolutionary origin of diphyodont tooth replacement, rapid juvenile growth and determinate adult growth. However, specific relationships among these characters during non-mammalian cynodont evolution require further exploration. Here, polarized light microscopy revealed incremental lines, resembling daily laminations of extant mammals, in histological sections of enamel in eight non-mammalian cynodont species. In the more basal non-probainognathian group, enamel extends extremely rapidly from cusp to cervix. By contrast, the enamel of mammaliamorphs is gradually accreted, with slow rates of crown extension, more typical of the majority of non-hypsodont crown mammals. These results are consistent with the reduction in dental replacement rate across the non-mammalian cynodont lineage, with greater rates of crown extension required in most non-probainognathians, and slower crown extension rates permitted in mammaliamorphs, which have reduced patterns of dental replacement in comparison with many non-probainognathians. The evolution of mammal-like growth patterns, with faster juvenile growth and more abruptly terminating adult growth, is linked with this reduction in dental replacement rates and may provide an additional explanation for the observed pattern in enamel growth rates. It is possible that the reduction in enamel extension rates in mammaliamorphs reflects an underlying reduction in skeletal growth rates at the time of postcanine formation, due to a more abruptly terminating pattern of adult growth in these more mammal-like, crownward species. PMID:29892415

  19. Amelogenesis Imperfect, Enamel Hypoplasia and Fluorosis Dental - Literature Review

    Directory of Open Access Journals (Sweden)

    Flávia Magnani Bevilacqua

    2015-12-01

    Full Text Available The developmental disorders of enamel are abnormalities of structure which can affect both dentitions. These abnormalities include amelogenesis imperfecta, enamel hypoplasia and dental fluorosis. The amelogenesis imperfecta is a hereditary change and enamel hypoplasia is a quantitative defect of enamel that occurs as a result of systemic problems, local and also inherited factors, or even the combination of them. Dental fluorosis is a hypoplasia caused by the chronic ingestion of fluoride during odontogenesis. All these anomalies have similar clinical characteristics, and it is necessary to be careful in their assessment. It is extremely important to know these abnormalities to establish a differential diagnosis and, consequently, a treatment plan, which can be set for each situation. Therefore, the purpose of this study was to review the literature regarding these three anomalies: amelogenesis imperfecta, enamel hypoplasia and dental fluorosis. It was concluded that to establish the differential diagnosis of these abnormalities as well as a proper treatment plan, it is indispensable the professional knowledge associated with the clinical examination. The examination has to consist of medical history and physical examination, and in some cases, x-ray examination.

  20. Indentation damage and crack repair in human enamel.

    Science.gov (United States)

    Rivera, C; Arola, D; Ossa, A

    2013-05-01

    Tooth enamel is the hardest and most highly mineralized tissue in the human body. While there have been a number of studies aimed at understanding the hardness and crack growth resistance behavior of this tissue, no study has evaluated if cracks in this tissue undergo repair. In this investigation the crack repair characteristics of young human enamel were evaluated as a function of patient gender and as a function of the distance from the Dentin Enamel Junction (DEJ). Cracks were introduced via microindentation along the prism direction and evaluated as a function of time after the indentation. Microscopic observations indicated that the repair of cracks began immediately after crack initiation and reaches saturation after approximately 48 h. During this process he crack length decreased up to 10% of the initial length, and the largest degree of reduction occurred in the deep enamel, nearest the DEJ. In addition, it was found that the degree of repair was significantly greater in the enamel of female patients. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. Indentation Damage and Crack Repair in Human Enamel*

    Science.gov (United States)

    Rivera, C.; Arola, D.; Ossa, A.

    2013-01-01

    Tooth enamel is the hardest and most highly mineralized tissue in the human body. While there have been a number of studies aimed at understanding the hardness and crack growth resistance behavior of this tissue, no study has evaluated if cracks in this tissue undergo repair. In this investigation the crack repair characteristics of young human enamel were evaluated as a function of patient gender and as a function of the distance from the Dentin Enamel Junction (DEJ). Cracks were introduced via microindentation along the prism direction and evaluated as a function of time after the indentation. Microscopic observations indicated that the repair of cracks began immediately after crack initiation and reaches saturation after approximately 48 hours. During this process he crack length decreased up to 10% of the initial length, and the largest degree of reduction occurred in the deep enamel, nearest the DEJ. In addition, it was found that the degree of repair was significantly greater in the enamel of female patients. PMID:23541701

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. In vitro evaluation of casein phosphopeptide-amorphous calcium phosphate effect on the shear bond strength of dental adhesives to enamel

    Directory of Open Access Journals (Sweden)

    Niloofar Shadman

    2015-01-01

    Full Text Available Background: Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP is applied for remineralization of early caries lesions or tooth sensitivity conditions and may affect subsequent resin bonding. This in vitro study investigated the effect of CPP-ACP on the shear bond strength of dental adhesives to enamel. Materials and Methods: Sixty extracted human molar teeth were selected and randomly divided into three groups and six subgroups. Buccal or lingual surfaces of teeth were prepared to create a flat enamel surface. Adhesives used were Tetric N-Bond, AdheSE and AdheSE One F. In three subgroups, before applying adhesives, enamel surfaces were treated with Tooth Mousse CPP-ACP for one hour, rinsed and stored in 37°C temperature with 100% humidity. This procedure was repeated for 5 days and then adhesives were applied and Tetric N-Ceram composite was adhered to the enamel. This procedure was also fulfilled for the other three subgroups without CPP-ACP treatment. After 24 hour water storage, samples were tested for shear bond strength test in a universal testing machine. Failure modes were determined by stereomicroscope. Data were analyzed by t-test and one-way analysis of variance with P 0.05. In non-applied CPP-ACP subgroups, there were statistically significant differences among all subgroups. Tetric N-Bond had the highest and AdheSE One F had the lowest shear bond strength. Conclusion: CPP-ACP application reduces the shear bond strength of AdheSE and AdheSE One F to enamel but not Tetric N-Bond.

  4. The impact of fluoride on ameloblasts and the mechanisms of enamel fluorosis

    NARCIS (Netherlands)

    Bronckers, A.L.J.J.; Lyaruu, D.M.; Denbesten, P.K.

    2009-01-01

    Intake of excess amounts of fluoride during tooth development cause enamel fluorosis, a developmental disturbance that makes enamel more porous. In mild fluorosis, there are white opaque striations across the enamel surface, whereas in more severe cases, the porous regions increase in size, with

  5. Study of the arrangement of crystallites in γ-irradiated human enamel by electron paramagnetic resonance

    International Nuclear Information System (INIS)

    Cevc, P.; Schara, M.; Ravnik, C.; Skaleric, U.

    1976-01-01

    The arrangement of tooth enamel microcrystals has been studied on CO 3 3- bound electrons by paramagnetic resonance. It was found that noncarious human maxillary central incisors have a greater degree of alignment of tooth enamel microcrystals than the carious ones. The outermost surface layer of enamel showed a greater crystallite degree of alignment than other parts

  6. Type VII collagen is enriched in the enamel organic matrix associated with the dentin-enamel junction of mature human teeth.

    Science.gov (United States)

    McGuire, Jacob D; Walker, Mary P; Mousa, Ahmad; Wang, Yong; Gorski, Jeff P

    2014-06-01

    The inner enamel region of erupted teeth is known to exhibit higher fracture toughness and crack growth resistance than bulk phase enamel. However, an explanation for this behavior has been hampered by the lack of compositional information for the residual enamel organic matrix. Since enamel-forming ameloblasts are known to express type VII collagen and type VII collagen null mice display abnormal amelogenesis, the aim of this study was to determine whether type VII collagen is a component of the enamel organic matrix at the dentin-enamel junction (DEJ) of mature human teeth. Immunofluorescent confocal microscopy of demineralized tooth sections localized type VII collagen to the organic matrix surrounding individual enamel rods near the DEJ. Morphologically, immunoreactive type VII collagen helical-bundles resembled the gnarled-pattern of enamel rods detected by Coomassie Blue staining. Western blotting of whole crown or enamel matrix extracts also identified characteristic Mr=280 and 230 kDa type VII dimeric forms, which resolved into 75 and 25 kDa bands upon reduction. As expected, the collagenous domain of type VII collagen was resistant to pepsin digestion, but was susceptible to purified bacterial collagenase. These results demonstrate the inner enamel organic matrix in mature teeth contains macromolecular type VII collagen. Based on its physical association with the DEJ and its well-appreciated capacity to complex with other collagens, we hypothesize that enamel embedded type VII collagen fibrils may contribute not only to the structural resilience of enamel, but may also play a role in bonding enamel to dentin. Copyright © 2014 Elsevier Inc. All rights reserved.

  7. Oropharynx lesion biopsy

    Science.gov (United States)

    ... as papilloma) Fungal infections (such as candida) Histoplasmosis Oral lichen planus Precancerous sore (leukoplakia) Viral infections (such as Herpes simplex) Risks Risks of the procedure may ... Throat lesion biopsy; Biopsy - mouth or throat; Mouth lesion biopsy; Oral cancer - biopsy ...

  8. Managing Carious Lesions

    DEFF Research Database (Denmark)

    Schwendicke, F; Frencken, J E; Bjørndal, L

    2016-01-01

    should be prioritized, while in shallow or moderately deep lesions, restoration longevity becomes more important. For teeth with shallow or moderately deep cavitated lesions, carious tissue removal is performed according toselective removal to firm dentine.In deep cavitated lesions in primary......The International Caries Consensus Collaboration undertook a consensus process and here presents clinical recommendations for carious tissue removal and managing cavitated carious lesions, including restoration, based on texture of demineralized dentine. Dentists should manage the disease dental...

  9. Modeling subsurface contamination at Fernald

    International Nuclear Information System (INIS)

    Jones, B.W.; Flinn, J.C.; Ruwe, P.R.

    1994-01-01

    The Department of Energy's Fernald site is located about 20 miles northwest of Cincinnati. Fernald produced refined uranium metal products from ores between 1953 and 1989. The pure uranium was sent to other DOE sites in South Carolina, Tennessee, Colorado,and Washington in support of the nation's strategic defense programs. Over the years of large-scale uranium production, contamination of the site's soil and groundwater occurred.The contamination is of particular concern because the Fernald site is located over the Great Miami Aquifer, a designated sole-source drinking water aquifer. Contamination of the aquifer with uranium was found beneath the site, and migration of the contamination had occurred well beyond the site's southern boundary. As a result, Fernald was placed on the National Priorities (CERCLA/Superfund) List in 1989. Uranium production at the site ended in 1989,and Fernald's mission has been changed to one of environmental restoration. This paper presents information about computerized modeling of subsurface contamination used for the environmental restoration project at Fernald

  10. Modeling Subsurface Hydrology in Floodplains

    Science.gov (United States)

    Evans, Cristina M.; Dritschel, David G.; Singer, Michael B.

    2018-03-01

    Soil-moisture patterns in floodplains are highly dynamic, owing to the complex relationships between soil properties, climatic conditions at the surface, and the position of the water table. Given this complexity, along with climate change scenarios in many regions, there is a need for a model to investigate the implications of different conditions on water availability to riparian vegetation. We present a model, HaughFlow, which is able to predict coupled water movement in the vadose and phreatic zones of hydraulically connected floodplains. Model output was calibrated and evaluated at six sites in Australia to identify key patterns in subsurface hydrology. This study identifies the importance of the capillary fringe in vadose zone hydrology due to its water storage capacity and creation of conductive pathways. Following peaks in water table elevation, water can be stored in the capillary fringe for up to months (depending on the soil properties). This water can provide a critical resource for vegetation that is unable to access the water table. When water table peaks coincide with heavy rainfall events, the capillary fringe can support saturation of the entire soil profile. HaughFlow is used to investigate the water availability to riparian vegetation, producing daily output of water content in the soil over decadal time periods within different depth ranges. These outputs can be summarized to support scientific investigations of plant-water relations, as well as in management applications.

  11. Introduction: energy and the subsurface

    Science.gov (United States)

    Viswanathan, Hari S.

    2016-01-01

    This theme issue covers topics at the forefront of scientific research on energy and the subsurface, ranging from carbon dioxide (CO2) sequestration to the recovery of unconventional shale oil and gas resources through hydraulic fracturing. As such, the goal of this theme issue is to have an impact on the scientific community, broadly, by providing a self-contained collection of articles contributing to and reviewing the state-of-the-art of the field. This collection of articles could be used, for example, to set the next generation of research directions, while also being useful as a self-study guide for those interested in entering the field. Review articles are included on the topics of hydraulic fracturing as a multiscale problem, numerical modelling of hydraulic fracture propagation, the role of computational sciences in the upstream oil and gas industry and chemohydrodynamic patterns in porous media. Complementing the reviews is a set of original research papers covering growth models for branched hydraulic crack systems, fluid-driven crack propagation in elastic matrices, elastic and inelastic deformation of fluid-saturated rock, reaction front propagation in fracture matrices, the effects of rock mineralogy and pore structure on stress-dependent permeability of shales, topographic viscous fingering and plume dynamics in porous media convection. This article is part of the themed issue ‘Energy and the subsurface’. PMID:27597784

  12. Pb enamel biomarker: Deposition of pre- and postnatal Pb isotope injection in reconstructed time points along rat enamel transect

    International Nuclear Information System (INIS)

    Rinderknecht, A.L.; Kleinman, M.T.; Ericson, J.E.

    2005-01-01

    Exposure to lead (Pb) as well as other heavy metals in the environment is still a matter of public health concern. The development of the enamel biomarker for heavy metal exposure assessment is designed to improve studies of dose-effect relationships to developmental anomalies, particularly embryonic dysfunctions, and to provide a time-specific recount of past exposures. The work presented in this paper demonstrates maternal transfer across the placental barrier of the enriched isotope 206 Pb tracer to the enamel of the rat pup. Likewise, injections of 204 Pb-enriched tracer in the neonate rat resulted in deposition of the tracer in the enamel histology as measured by secondary ion microprobe spectrometry. Through enamel, we were able to observe biological removal and assimilation of prenatal and postnatal tracers, respectively. This research demonstrates that enamel can be used as a biomarker of exposure to Pb and may illustrate the toxicokinetics of incorporating Pb into fetal and neonatal steady-state system processes. The biomarker technique, when completely developed, may be applied to cross-sectional and longitudinal epidemiological research

  13. The Chernobyl accident: EPR dosimetry on dental enamel of children

    International Nuclear Information System (INIS)

    Gualtieri, G.; Colacicchi, S.; Sgattoni, R.; Giannoni, M.

    2001-01-01

    The radiation dose on tooth enamel of children living close to Chernobyl has been evaluated by EPR. The sample preparation was reduced to a minimum of mechanical steps to remove a piece of enamel. A standard X-ray tube at low energy was used for additive irradiation. The filtration effect of facial soft tissue was taken into account. The radiation dose for a group of teeth slightly exceeds the annual dose, whereas for another group the dose very much exceeds the annual dose. Since the higher dose is found in teeth whose enamel have much lower EPR sensitivity to the radiation, it can be suggested that for these teeth the native signal could alter the evaluation of the smaller radiation signal

  14. Evaluation of the bleached human enamel by Scanning Electron Microscopy

    DEFF Research Database (Denmark)

    Miranda, Carolina Baptista; Pagani, Clovis; Benetti, Ana Raquel

    2005-01-01

    Since bleaching has become a popular procedure, the effect of peroxides on dental hard tissues is of great interest in research. Purpose: The aim of this in vitro study was to perform a qualitative analysis of the human enamel after the application of in-office bleaching agents, using Scanning......: 2h); G3- four 2-hour exposures to 35% carbamide peroxide (total exposure: 8h); G4- two applications of 35% hydrogen peroxide, which was light-activated with halogen lamp at 700mW/cm² during 7min and remained in contact with enamel for 20min (total exposure: 40min). All bleaching treatments adopted...... analysis performing gold sputter coating under vacuum and were examined using 15kV at 500x and 2000x magnification. Results: Morphological alterations on the enamel surface were similarly detected after bleaching with either 35% carbamide peroxide or 35% hydrogen peroxide. Surface porosities were...

  15. Remineralization of enamel lesion. A study of the physico-chemical mechanism.

    NARCIS (Netherlands)

    Cate, Jacob Martien ten

    1979-01-01

    This thesis contains data on the remineralization occurring in very simplified “oral fluid”. As such, this study needs a follow-up in experiments in wich more parameters of the oral environment and the oral fluid will be simulated in more detail. There is no doubt that remineralization will be one

  16. Prevention and treatment of white spot lesions in orthodontic patients

    Directory of Open Access Journals (Sweden)

    Maryam Khoroushi

    2017-01-01

    Full Text Available Decalcification of enamel, appearing as white spot lesions (WSLs, around fixed orthodontic appliances is a major challenge during and after fixed orthodontic treatment by considering the fact that the goal of orthodontic treatment is to enhance facial and dental esthetic appearance. Banded or bonded teeth exhibit a significantly higher rate of WSLs compared to the controls with no braces as fixed appliances and the bonding materials promote retention of biofilms. These lesions are managed in the first step by establishing good oral hygiene habits and prophylaxis with topical fluorides, including high-fluoride toothpastes, fluoride mouthwashes, gels, varnishes, fluoride-containing bonding materials, and elastic ligatures. Recently, other materials and methods have been recommended, including the application of casein phosphopeptides-amorphous calcium phosphate, antiseptics, probiotics, polyols, sealants, laser, tooth bleaching agents, resin infiltration, and microabrasion. This article reviews the currently used methods to manage enamel demineralization during and after orthodontic treatment and the risk factors and preventive measures based on the latest evidence.

  17. Enamel thickness after preparation of tooth for porcelain laminate.

    Science.gov (United States)

    Pahlevan, Ayoub; Mirzaee, Mansoreh; Yassine, Esmaeil; Ranjbar Omrany, Ladan; Hasani Tabatabaee, Masumeh; Kermanshah, Hamid; Arami, Sakineh; Abbasi, Mehdy

    2014-07-01

    In this investigation the thickness of enamel in the gingival, middle, and incisal thirds of the labial surface of the anterior teeth were measured regarding preparation of the teeth for porcelain laminate veneers. Part one, 20 extracted intact human maxillary central and lateral incisors ten of each were selected. The teeth were imbedded in autopolimerize acrylic resin. Cross section was preformed through the midline of the incisal, middle and cervical one-third of the labial surface of the teeth. The samples were observed under reflected stereomicroscope and the thickness of enamel was recorded. Part II, the effect of different types of preparation on dentin exposure was evaluated. Thirty maxillary central incisor teeth were randomly divided into two groups: A: Knife-edge preparation. B: Chamfer preparation. All samples were embedded in autopolimerize acrylic resin using a silicon mold. The samples were cut through the midline of the teeth. The surface of the samples were polished and enamel and dentin were observed under the stereomicroscope. Data were analyzed by ANOVA-one way test. The results of this study showed that the least enamel thickness in the central incisor was 345 and in lateral incisor is 235 μ this thickness is related to the one-third labial cervical area. Maximum thickness in maxillary central and lateral incisors in the one-third labial incisal surface was 1260 μ and 1220μ, respectively. In the second part of the study, the tendency of dentinal exposure was shown with the chamfer preparation, but no dentinal exposure was found in the knife-edge preparation. The differences between groups were significant (p<0.05). The knowledge of enamel thickness in different part of labial surface is very important. The thickness of enamel in the gingival area does not permit a chamfer preparation. The knife edge preparation is preferable in gingival area.

  18. Enamel thickness after preparation of tooth for porcelain laminate.

    Directory of Open Access Journals (Sweden)

    Ayoub Pahlevan

    2014-08-01

    Full Text Available In this investigation the thickness of enamel in the gingival, middle, and incisal thirds of the labial surface of the anterior teeth were measured regarding preparation of the teeth for porcelain laminate veneers.Part one, 20 extracted intact human maxillary central and lateral incisors ten of each were selected. The teeth were imbedded in autopolimerize acrylic resin. Cross section was preformed through the midline of the incisal, middle and cervical one-third of the labial surface of the teeth. The samples were observed under reflected stereomicroscope and the thickness of enamel was recorded. Part II, the effect of different types of preparation on dentin exposure was evaluated. Thirty maxillary central incisor teeth were randomly divided into two groups: A: Knife-edge preparation. B: Chamfer preparation. All samples were embedded in autopolimerize acrylic resin using a silicon mold. The samples were cut through the midline of the teeth. The surface of the samples were polished and enamel and dentin were observed under the stereomicroscope.Data were analyzed by ANOVA-one way test. The results of this study showed that the least enamel thickness in the central incisor was 345 and in lateral incisor is 235 μ this thickness is related to the one-third labial cervical area. Maximum thickness in maxillary central and lateral incisors in the one-third labial incisal surface was 1260 μ and 1220μ, respectively. In the second part of the study, the tendency of dentinal exposure was shown with the chamfer preparation, but no dentinal exposure was found in the knife-edge preparation. The differences between groups were significant (p<0.05.The knowledge of enamel thickness in different part of labial surface is very important. The thickness of enamel in the gingival area does not permit a chamfer preparation. The knife edge preparation is preferable in gingival area.

  19. Quantitative analysis of enamel on debonded orthodontic brackets.

    Science.gov (United States)

    Cochrane, Nathan J; Lo, Thomas W G; Adams, Geoffrey G; Schneider, Paul M

    2017-09-01

    Iatrogenic damage to the tooth surface in the form of enamel tearouts can occur during removal of fixed orthodontic appliances. The aim of this study was to assess debonded metal and ceramic brackets attached with a variety of bonding materials to determine how frequently this type of damage occurs. Eighty-one patients close to finishing fixed orthodontic treatment were recruited. They had metal brackets bonded with composite resin and a 2-step etch-and-bond technique or ceramic brackets bonded with composite resin and a 2-step etch-and- bond technique, and composite resin with a self-etching primer or resin-modified glass ionomer cement. Debonded brackets were examined by backscattered scanning electron microscopy with energy dispersive x-ray spectroscopy to determine the presence and area of enamel on the base pad. Of the 486 brackets collected, 26.1% exhibited enamel on the bonding material on the bracket base pad. The incidences of enamel tearouts for each group were metal brackets, 13.3%; ceramic brackets, 30.2%; composite resin with self-etching primer, 38.2%; and resin-modified glass ionomer cement, 21.2%. The percentage of the bracket base pad covered in enamel was highly variable, ranging from 0% to 46.1%. Enamel damage regularly occurred during the debonding process with the degree of damage being highly variable. Damage occurred more frequently when ceramic brackets were used (31.9%) compared with metal brackets (13.3%). Removal of ceramic brackets bonded with resin-modified glass ionomer cement resulted in less damage compared with the resin bonding systems. Copyright © 2017 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  20. Recovery of crystallographic texture in remineralized dental enamel.

    Science.gov (United States)

    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

  1. Electron paramagnetic resonance biophysical radiation dosimetry with tooth enamel

    International Nuclear Information System (INIS)

    Khan, Rao F.H.

    2003-01-01

    This thesis deals with the advancements made in the field of Electron Paramagnetic Resonance (EPR) for biophysical dosimetry with tooth enamel for accident, emergency, and retrospective radiation dose reconstruction. A methodology has been developed to measure retrospective radiation exposures in human tooth enamel. This entails novel sample preparation procedures with minimum mechanical treatment to reduce the preparation induced uncertainties, establish optimum measurement conditions inside the EPR cavity, post-process the measured spectrum with functional simulation of dosimetric and other interfering signals, and reconstruct dose. By using this technique, retrospective gamma exposures as low as 80±30 mGy have been successfully deciphered. The notion of dose modifier was introduced in EPR biodosimetry for low dose measurements. It has been demonstrated that by using the modified zero added dose (MZAD) technique for low radiation exposures, doses in 100 mGy ranges can be easily reconstructed in teeth that were previously thought useless for EPR dosimetry. Also, the use of a dose modifier makes robust dose reconstruction possible for higher radiation exposures. The EPR dosimetry technique was also developed for tooth samples extracted from rodents, which represent small tooth sizing. EPR doses in the molars, extracted from the mice irradiated with whole body exposures, were reassessed and shown to be correct within the experimental uncertainty. The sensitivity of human tooth enamel for neutron irradiation, obtained from the 3 MV McMaster K.N. Van de Graaff accelerator, was also studied. For the first time this work has shown that the neutron sensitivity of the tooth enamel is approximately 1/10th of the equivalent gamma sensitivity. Parametric studies for neutron dose rate and neutron energy within the available range of the accelerator, showed no impact on the sensitivity of the tooth enamel. Therefore, tooth enamel can be used as a dosimeter for both neutrons

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

    Directory of Open Access Journals (Sweden)

    Carolina Loch

    Full Text Available 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

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

    Science.gov (United States)

    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

  4. A model for predicting wear rates in tooth enamel.

    Science.gov (United States)

    Borrero-Lopez, Oscar; Pajares, Antonia; Constantino, Paul J; Lawn, Brian R

    2014-09-01

    It is hypothesized that wear of enamel is sensitive to the presence of sharp particulates in oral fluids and masticated foods. To this end, a generic model for predicting wear rates in brittle materials is developed, with specific application to tooth enamel. Wear is assumed to result from an accumulation of elastic-plastic micro-asperity events. Integration over all such events leads to a wear rate relation analogous to Archard׳s law, but with allowance for variation in asperity angle and compliance. The coefficient K in this relation quantifies the wear severity, with an arbitrary distinction between 'mild' wear (low K) and 'severe' wear (high K). Data from the literature and in-house wear-test experiments on enamel specimens in lubricant media (water, oil) with and without sharp third-body particulates (silica, diamond) are used to validate the model. Measured wear rates can vary over several orders of magnitude, depending on contact asperity conditions, accounting for the occurrence of severe enamel removal in some human patients (bruxing). Expressions for the depth removal rate and number of cycles to wear down occlusal enamel in the low-crowned tooth forms of some mammals are derived, with tooth size and enamel thickness as key variables. The role of 'hard' versus 'soft' food diets in determining evolutionary paths in different hominin species is briefly considered. A feature of the model is that it does not require recourse to specific material removal mechanisms, although processes involving microplastic extrusion and microcrack coalescence are indicated. Published by Elsevier Ltd.

  5. Recovery of crystallographic texture in remineralized dental enamel.

    Directory of Open Access Journals (Sweden)

    Samera Siddiqui

    Full Text Available 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

  6. Assessment of White Spot Lesions and In-Vivo Evaluation of the Effect of CPP-ACP on White Spot Lesions in Permanent Molars of Children.

    Science.gov (United States)

    Munjal, Deepti; Garg, Shalini; Dhindsa, Abhishek; Sidhu, Gagandeep Kaur; Sethi, Harsimran Singh

    2016-05-01

    As hindrance of remineralisation process occurs during orthodontic therapy resulting in decalcification of enamel because number of plaque retention sites increases due to banding and bonding of appliances to teeth. The present analytic study was undertaken to assess the occurrence of white spot lesions in permanent molars of children with and without orthodontic therapy and to evaluate the effect of Casein PhosphoPeptide-Amorphous Calcium Phosphate (CPP-ACP) on white spot lesions in post-orthodontic patients in a given period of time. The study comprised of examination of 679 first permanent molars which were examined to assess the occurrence of smooth surface white spot lesions in children of 8 to 16 years age group. Group I comprised subjects without any orthodontic treatment and Group II comprised of subjects who had undergone orthodontic therapy. The sample size was calculated using the epi-info6 computer package. Treatment group included 20 post-orthodontic patients examined with at least one white spot lesion within the enamel who received remineralizing cream (GC Tooth Mousse, Recaldent, GC Corporation.) i.e., CPP-ACP cream two times a day for 12 consecutive weeks. Computerized image analysis method was taken to evaluate white spot lesions. These frequency and percentages were compared with chi-square test. For comparison of numeric data, paired t-test was used. Of the total 278 (49.6%) first permanent molars showed occurrence of smooth surface white spot lesions out of 560 in Group I and 107 (89.9%) first permanent molars showed presence of white spot lesions out of 119 debanded first permanent molars of children examined in Group II. CPP-ACP therapy group showed reduction in severity of codes which was found to be highly significant after 12 weeks and eight weeks on gingival-third, p-value (spot lesions on teeth undergoing fixed orthodontic therapy according to the present study.

  7. Periodontal bone lesions

    International Nuclear Information System (INIS)

    Linden, L.W.J. van der.

    1985-01-01

    In the course of life the periodontum is subject to changes which may be physiological or pathological. Intraoral radiographs give insight into the hard structures of the dentomaxillar region and provides information on lesions in the bone of the periodontum in that they show radiopacities and radiolucencies caused by such lesions. In this thesis the relation is investigated between the true shape and dimensions of periodontal bone lesions and their radiographic images. A method is developed and tested of making standardized and reproducible radiographs suitable for longitudinal studies of periodontal lesions. Also the possibility is demonstrated of an objective and reproducible interpretation of radiographic characteristics of periodontal bone lesions. (Auth.)

  8. Effects of etching time on enamel bond strengths.

    Science.gov (United States)

    Triolo, P T; Swift, E J; Mudgil, A; Levine, A

    1993-12-01

    This study evaluated the effects of etching time on bond strengths of composite to enamel. Proximal surfaces of extracted molars were etched with either a conventional etchant (35% phosphoric acid) or one of two dentin/enamel conditioners, 10% maleic acid (Scotchbond Multi-Purpose Etchant), or a solution of oxalic acid, aluminum nitrate, and glycine (Gluma 1 & 2 Conditioner). Each agent was applied for 15, 30, or 60 seconds. Specimens etched with 35% phosphoric acid had the highest mean bond strengths at each etching time. At the manufacturer's recommended application times, the other two agents gave significantly lower shear bond strengths than phosphoric acid.

  9. Inter-proximal enamel reduction in contemporary orthodontics.

    Science.gov (United States)

    Pindoria, J; Fleming, P S; Sharma, P K

    2016-12-16

    Inter-proximal enamel reduction has gained increasing prominence in recent years being advocated to provide space for orthodontic alignment, to refine contact points and to potentially improve long-term stability. An array of techniques and products are available ranging from hand-held abrasive strips to handpiece mounted burs and discs. The indications for inter-proximal enamel reduction and the importance of formal space analysis, together with the various techniques and armamentarium which may be used to perform it safely in both the labial and buccal segments are outlined.

  10. Mammalian enamel maturation: Crystallographic changes prior to tooth eruption

    Czech Academy of Sciences Publication Activity Database

    Kallistová, Anna; Horáček, I.; Šlouf, Miroslav; Skála, Roman; Fridrichová, Michaela

    2017-01-01

    Roč. 12, č. 2 (2017), č. článku e0171424. E-ISSN 1932-6203 R&D Projects: GA MŠk(CZ) LO1507 Institutional support: RVO:67985831 ; RVO:61389013 Keywords : resolution electron-microscopy * atomic-force microscopy * dental enamel * vertebrate dentition * rat enamel * protein * evolution * crystals * shape * ameloblastin Subject RIV: EH - Ecology, Behaviour; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Other biological topics; Polymer science (UMCH-V) Impact factor: 2.806, year: 2016

  11. Surface changes of enamel after brushing with charcoal toothpaste

    Science.gov (United States)

    Pertiwi, U. I.; Eriwati, Y. K.; Irawan, B.

    2017-08-01

    The aim of this study was to determine the surface roughness changes of tooth enamel after brushing with charcoal toothpaste. Thirty specimens were brushed using distilled water (the first group), Strong® Formula toothpaste (the second group), and Charcoal® Formula toothpaste for four minutes and 40 seconds (equivalent to one month) and for 14 minutes (equivalent to three months) using a soft fleece toothbrush with a mass of 150 gr. The roughness was measured using a surface roughness tester, and the results were tested with repeated ANOVA test and one-way ANOVA. The value of the surface roughness of tooth enamel was significantly different (penamel.

  12. Non-specific esterases in partly mineralized bovine enamel

    DEFF Research Database (Denmark)

    Moe, D; Kirkeby, S

    1990-01-01

    Activity for non-specific esterase was demonstrated in the matrix of developing bovine enamel with alpha-naphthyl acetate and 5-bromoindoxyl acetate as the esterase substrates. By use of high-performance liquid chromatography gel filtration, ion-exchange chromatography, and electrophoresis three...... esterases were shown to be present in the enamel matrix. The enzymes showed highest activity at pH 6.5-7.5. In sections a strong reaction was observed in the secretory ameloblasts. The esterases may be proteolytic enzymes that participate in the degradation of the matrix proteins....

  13. SUBSURFACE REPOSITORY INTEGRATED CONTROL SYSTEM DESIGN

    International Nuclear Information System (INIS)

    Randle, D.C.

    2000-01-01

    The primary purpose of this document is to develop a preliminary high-level functional and physical control system architecture for the potential repository at Yucca Mountain. This document outlines an overall control system concept that encompasses and integrates the many diverse process and communication systems being developed for the subsurface repository design. This document presents integrated design concepts for monitoring and controlling the diverse set of subsurface operations. The Subsurface Repository Integrated Control System design will be composed of a series of diverse process systems and communication networks. The subsurface repository design contains many systems related to instrumentation and control (I andC) for both repository development and waste emplacement operations. These systems include waste emplacement, waste retrieval, ventilation, radiological and air monitoring, rail transportation, construction development, utility systems (electrical, lighting, water, compressed air, etc.), fire protection, backfill emplacement, and performance confirmation. Each of these systems involves some level of I andC and will typically be integrated over a data communications network throughout the subsurface facility. The subsurface I andC systems will also interface with multiple surface-based systems such as site operations, rail transportation, security and safeguards, and electrical/piped utilities. In addition to the I andC systems, the subsurface repository design also contains systems related to voice and video communications. The components for each of these systems will be distributed and linked over voice and video communication networks throughout the subsurface facility. The scope and primary objectives of this design analysis are to: (1) Identify preliminary system-level functions and interfaces (Section 6.2). (2) Examine the overall system complexity and determine how and on what levels the engineered process systems will be monitored

  14. DOE UST interim subsurface barrier technologies workshop

    International Nuclear Information System (INIS)

    1992-09-01

    This document contains information which was presented at a workshop regarding interim subsurface barrier technologies that could be used for underground storage tanks, particularly the tank 241-C-106 at the Hanford Reservation

  15. Design and maintenance of subsurface gravel wetlands.

    Science.gov (United States)

    2015-02-01

    This report summarizes the University of New Hampshire Stormwater Center (UNHSC) evaluation of : a review of Subsurface Gravel Wetlands design and specifications used by the New Hampshire : Department of Transportation (NHDOT or Department). : Subsur...

  16. Component-based framework for subsurface simulations

    International Nuclear Information System (INIS)

    Palmer, B J; Fang, Yilin; Hammond, Glenn; Gurumoorthi, Vidhya

    2007-01-01

    Simulations in the subsurface environment represent a broad range of phenomena covering an equally broad range of scales. Developing modelling capabilities that can integrate models representing different phenomena acting at different scales present formidable challenges both from the algorithmic and computer science perspective. This paper will describe the development of an integrated framework that will be used to combine different models into a single simulation. Initial work has focused on creating two frameworks, one for performing smooth particle hydrodynamics (SPH) simulations of fluid systems, the other for performing grid-based continuum simulations of reactive subsurface flow. The SPH framework is based on a parallel code developed for doing pore scale simulations, the continuum grid-based framework is based on the STOMP (Subsurface Transport Over Multiple Phases) code developed at PNNL Future work will focus on combining the frameworks together to perform multiscale, multiphysics simulations of reactive subsurface flow

  17. Subsurface Prospecting by Planetary Drones, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed program innovates subsurface prospecting by planetary drones to seek a solution to the difficulty of robotic prospecting, sample acquisition, and sample...

  18. Effect of ethanol-wet-bonding technique on resin–enamel bonds

    Directory of Open Access Journals (Sweden)

    Muhammet Kerim Ayar

    2014-03-01

    Conclusion: The ethanol-wet-bonding technique may increase the bond strength of commercial adhesives to enamel. The chemical composition of the adhesives can affect the bond strength of adhesives when bonding to acid-etched enamel, using the ethanol-wet-bonding technique. Some adhesive systems used in the present study may simultaneously be applied to enamel and dentin using ethanol-wet-bonding. Furthermore, deploying ethanol-wet-bonding for the tested commercial adhesives to enamel can increase the adhesion abilities of these adhesives to enamel.

  19. Thermal Transformations of Iron Cations in the System Metal-Vitreous Enamel Coat. Moessbauer Spectroscopic Study

    International Nuclear Information System (INIS)

    Barcova, K.; Mashlan, M.; Zboril, R.; Hrabovska, K.

    2005-01-01

    Vitreous enameling on steel is carried out to provide a protective layer against chemical corrosion from the surrounding environment. The glass bonds with the steel to form a composite material. The Moessbauer spectroscopy was firstly applied to study the vitreous enameling in which the complex of processes, as diffusion of species, adhesion between the glass and the steel, galvanic reactions, plays an important role. The Moessbauer spectroscopy provides unique information about the Fe-phase structure of the vitreous enamel layer and that of the steel-enamel interface. Diffusion of iron from steel surface towards enamel layer and formation of a new Fe2+ phase was proved

  20. Determination of fracture toughness of human permanent and primary enamel using an indentation microfracture method.

    Science.gov (United States)

    Hayashi-Sakai, Sachiko; Sakai, Jun; Sakamoto, Makoto; Endo, Hideaki

    2012-09-01

    The purpose of the present study was to examine the fracture toughness and Vickers microhardness number of permanent and primary human enamel using the indentation microfracture method. Crack resistance and a parameter indirectly related to fracture toughness were measured in 48 enamel specimens from 16 permanent teeth and 12 enamel specimens obtained from six primary teeth. The Vickers microhardness number of the middle portion was greater than the upper portion in primary enamel. The fracture toughness was highest in the middle portion of permanent enamel, because fracture toughness greatly depends upon microstructure. These findings suggest that primary teeth are not miniature permanent teeth but have specific and characteristic mechanical properties.

  1. An in vitro study of dental enamel wear by restorative materials using radiometric method

    International Nuclear Information System (INIS)

    Adachi, Lena Katekawa

    2000-01-01

    There is an increasing demand and interest to study the dental materials wear as well as about the abrasion effect on antagonistic teeth. Due to the fact that the existent restorative materials have no specifications about their abrasiveness, it is necessary the establishment of degrees of comparison among them to support clinical application. In this work, the radiometric method was applied to study the enamel wear caused by another enamel and by restorative materials (Ceramco II, Noritake and Finesse porcelains, Artglass and Targis). The dental enamel made radioactive by irradiation at the IEA-R1m nuclear research reactor under a thermal neutron flux was submitted to wear in a machine which allows sliding motion of an antagonistic surface in contact with this radioactive enamel. The enamel wear was evaluated by measuring beta activity of 32 P transferred to water from this irradiated tooth. Results obtained indicated that dental porcelains cause pronounced enamel wear when compared with that provoked by another enamel or by resin materials. Resin materials caused less enamel wear than another enamel. Vickers microhardness data obtained for antagonistic materials showed a correlation with the wear caused to the enamel. This study allowed to conclude that the radiometric method proposed can be used satisfactorily in the evaluation of enamel wear by restorative materials. This method presents advantages due to quick responses and ease of analyses There is (author)

  2. On the critical parameters that regulate the deformation behaviour of tooth enamel.

    Science.gov (United States)

    Xie, Zonghan; Swain, Michael; Munroe, Paul; Hoffman, Mark

    2008-06-01

    Tooth enamel is the hardest tissue in the human body with a complex hierarchical structure. Enamel hypomineralisation--a developmental defect--has been reported to cause a marked reduction in the mechanical properties of enamel and loss of dental function. We discover a distinctive difference in the inelastic deformation mechanism between sound and hypomineralised enamels that is apparently controlled by microstructural variation. For sound enamel, when subjected to mechanical forces the controlling deformation mechanism was distributed shearing within nanometre thick protein layer between its constituent mineral crystals; whereas for hypomineralised enamel microcracking and subsequent crack growth were more evident in its less densely packed microstructure. We develop a mechanical model that not only identifies the critical parameters, i.e., the thickness and shear properties of enamels, that regulate the mechanical behaviour of enamel, but also explains the degradation of hypomineralised enamel as manifested by its lower resistance to deformation and propensity for catastrophic failure. With support of experimental data, we conclude that for sound enamel an optimal microstructure has been developed that endows enamel with remarkable structural integrity for durable mechanical function.

  3. Quantitative assessment of the enamel machinability in tooth preparation with dental diamond burs.

    Science.gov (United States)

    Song, Xiao-Fei; Jin, Chen-Xin; Yin, Ling

    2015-01-01

    Enamel cutting using dental handpieces is a critical process in tooth preparation for dental restorations and treatment but the machinability of enamel is poorly understood. This paper reports on the first quantitative assessment of the enamel machinability using computer-assisted numerical control, high-speed data acquisition, and force sensing systems. The enamel machinability in terms of cutting forces, force ratio, cutting torque, cutting speed and specific cutting energy were characterized in relation to enamel surface orientation, specific material removal rate and diamond bur grit size. The results show that enamel surface orientation, specific material removal rate and diamond bur grit size critically affected the enamel cutting capability. Cutting buccal/lingual surfaces resulted in significantly higher tangential and normal forces, torques and specific energy (pmachinability for clinical dental practice. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Error in assessing the absorbed dose from the EPR signal from dental enamel

    International Nuclear Information System (INIS)

    Kleshchenko, E.D.; Kushnereva, K.K.

    1997-01-01

    Dose measurements from EPR signals from dental enamel were analyzed in a random sampling of 100 teeth extracted in liquidators of the Chernobyl accident aftermath and the EPR spectra of dental enamel of 80 intact teeth from children studied. The mean square deviation of enamel sensitivity to ionizing radiation in some teeth is approximately 0.3 of the mean sensitivity value. The variability of the nature EPR spectrum of dental enamel limits in principle the lower threshold of EPR-measured 60 mGy doses. When assessing the individual absorbed doses from the EPR signal from dental enamel without additional exposure it is necessary to bear in mind the extra error of approximately 6-% at a confidence probability P=0.95 caused by the variability of enamel sensitivity to radiation in some teeth. This additional error may be ruled out by graduated additional exposure of the examined enamel samples

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

    Science.gov (United States)

    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. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  6. Evaluation of the Esthetic Properties of Developmental Defects of Enamel: A Spectrophotometric Clinical Study

    Directory of Open Access Journals (Sweden)

    Fabrizio Guerra

    2015-01-01

    Full Text Available Objectives. Detailed clinical quantification of optical properties of developmental defect of enamel is possible with spectrophotometric evaluation. Developmental defects of enamel (DDE are daily encountered in clinical practice. DDE are an alteration in quality and quantity of the enamel, caused by disruption and/or damage to the enamel organ during amelogenesis. Methods. Several clinical indices have been developed to categorize enamel defects based on their nature, appearance, microscopic features, or cause. A sample of 39 permanent teeth presenting DDE on labial surface was examined using the DDE Modified Index and SpectroShade evaluation. The spectrophotometric approach quantifies L* (luminosity, a* (quantity of green-red, and b* (quantity of blue-yellow of different DDE. Conclusions. SpectroShade evaluation of the optical properties of the enamel defect enhances clinical understanding of severity and extent of the defect and characterizes the enamel alteration in terms of color discrepancy and surface characterization.

  7. Distinguishing between enamel fluorosis and other enamel defects in permanent teeth of children

    Directory of Open Access Journals (Sweden)

    Aira Sabokseir

    2016-02-01

    Full Text Available Background. The inconsistent prevalence of fluorosis for a given level of fluoride in drinking water suggests developmental defects of enamel (DDEs other than fluorosis were being misdiagnosed as fluorosis. The imprecise definition and subjective perception of fluorosis indices could result in misdiagnosis of dental fluorosis. This study was conducted to distinguish genuine fluorosis from fluorosis-resembling defects that could have adverse health-related events as a cause using Early Childhood Events Life-grid method (ECEL. Methods. A study was conducted on 400 9-year-old children from areas with high, optimal and low levels of fluoride in the drinking water of Fars province, Iran. Fluorosis cases were diagnosed on the standardized one view photographs of the anterior teeth using Dean’s and TF (Thylstrup and Fejerskov Indices by calibrated dentists. Agreements between examiners were tested. Early childhood health-related data collected retrospectively by ECEL method were matched with the position of enamel defects. Results. Using both Dean and TF indices three out of four dentists diagnosed that 31.3% (115 children had fluorosis, 58.0%, 29.1%, and 10.0% in high (2.12–2.85 ppm, optimal (0.62–1.22 ppm, and low (0.24–0.29 ppm fluoride areas respectively (p < 0.001. After matching health-related events in the 115 (31.3% of children diagnosed with fluorosis, 31 (8.4% of children had fluorosis which could be matched with their adverse health-related events. This suggests that what was diagnosed as fluorosis were non-fluoride related DDEs that resemble fluorosis. Discussion. The frequently used measures of fluorosis appear to overscore fluorosis. Use of ECEL method to consider health related events relevant to DDEs could help to differentiate between genuine fluorosis and fluorosis-resembling defects.

  8. Effects of Treatment with Various Remineralizing Agents on the Microhardness of Demineralized Enamel Surface

    Directory of Open Access Journals (Sweden)

    Kiana Salehzadeh Esfahani

    2015-12-01

    Full Text Available Background and aims. Remineralization of incipient caries is one of the goals in dental health care. The present study aimed at comparing the effects of casein phosphopeptide-amorphous calcium phosphate complex (CPP-ACP, Remin Pro®, and 5% sodium fluoride varnish on remineralization of enamel lesions. Materials and methods. In this in vitro study, 60 enamel samples were randomly allocated to six groups of 10. After four days of immersion in demineralizing solution, microhardness of all samples was measured. Afterward, groups 1-3 under-went one-time treatment with fluoride varnish, CPP-ACP, and Remin Pro®, respectively. Microhardness of groups 4-6 was measured not only after one-month treatment with the above-mentioned materials (for eight hours a day, but also after re-exposing to the demineralizing solution. The results were analyzed by one-way analysis of variance (ANOVA, repeated measures ANOVA, and Fisher’s least significant difference (LSD test. Results. None of the regimens could increase microhardness in groups 1-3. However, one-month treatment regimens in groups 4-6 caused a significant increase in microhardness. The greatest microhardness was detected in the group treated with CPP-ACP (P = 0.001. In addition, although microhardness reduced following re-demineralization in all three groups, the mean reduction was minimum in the CPP-ACP-treated group (P < 0.001. Conclusion. While long-term repeated application of all compounds improved microhardness, the remineralization potential of CPP-ACP was significantly higher than that of Remin Pro® and sodium fluoride varnish.

  9. Enamel hypoplasia in deciduous teeth of great apes: do differences in defect prevalence imply differential levels of physiological stress?

    Science.gov (United States)

    Lukacs, J R

    1999-11-01

    five times more often than maxillary canine teeth. Differences in LHPC prevalence by sex are small and not significant. Intergeneric differences are large and non-random: chimpanzees (Pan) exhibit a significantly lower frequency of LHPC (22%, n = 50) by individual count, than either the orangutan (Pongo, 88.0%, n = 25) or the gorilla (Gorilla, 88.7%, n = 53). Tooth count prevalences exhibit a similar pattern of variation and are also statistically significant. These findings suggest that large bodied great apes (gorilla and orangutan) may be under greater physiological stress during perinatal and early postnatal development than the chimpanzee. The size, position, and timing of LHPC lesions are currently under analysis and may yield more insight into the etiological origin of this enamel defect. Copyright 1999 Wiley-Liss, Inc.

  10. Shear bond strength of hydrophilic adhesive systems to enamel.

    Science.gov (United States)

    Hara, A T; Amaral, C M; Pimenta, L A; Sinhoreti, M A

    1999-08-01

    To compare the enamel shear bond strength of four hydrophilic adhesive systems: one multiple-bottle (Scotchbond Multi-Purpose Plus), two one-bottle (Stae, Single Bond) and one self-etching (Etch & Prime). 120 bovine incisor teeth were obtained, embedded in polyester resin, polished to 600 grit to form standardized enamel surfaces, and randomly assigned to four groups (n = 30). Each adhesive system was used on enamel according to the manufacturer's instructions, and resin-based composite (Z100) cylinders with 3 mm diameter and 5 mm height were bonded. Specimens were stored in humid environment for 1 week, and bond strength was determined using a universal testing machine, at a crosshead speed of 0.5 mm/minute. The mean shear bond strength values (MPa +/- SD) were: Single Bond: 24.28 +/- 5.27 (a); Scotchbond Multi-Purpose Plus: 21.18 +/- 4.35 (ab); Stae: 19.56 +/- 4.71 (b); Etch & Prime 3.0: 15.13 +/- 4.92 (c). ANOVA revealed significant difference in means (P < 0.01) and Tukey's test showed the statistical differences that are expressed by different letters for each group. It could be concluded that the self-etching adhesive system did not provide as good a bond to enamel surface, as did the one- and multiple-bottle systems.

  11. The remineralisation of enamel: a review of the literature.

    Science.gov (United States)

    Li, Xiaoke; Wang, Jinfang; Joiner, Andrew; Chang, Jiang

    2014-06-01

    The purpose of this paper is to review current knowledge and technologies for tooth remineralisation. The literature was searched using the "Scopus" and "Web of Knowledge" database from the year 1971, with principal key words of *miner*, teeth and enamel. Language was restricted to English. Original studies and reviews were included. Conference papers and posters were excluded. The importance of oral health for patients and consumers has seen a steady increase in the number of tooth remineralisation agents, products and procedures over recent years. Concomitantly, there has been continued publication of both in vivo and in vitro tooth remineralisation and demineralisation studies. It is clear that fluoride treatments are generally effective in helping to protect the dental enamel from demineralisation and enhancing remineralisation. Continued efforts to increase the efficacy of fluoride have been made, in particular, by the addition of calcium salts or calcium containing materials to oral care products which may enhance the delivery and retention of fluoride into the oral cavity. In addition, the calcium salts or materials may act as additional sources of calcium to promote enamel remineralisation or reduce demineralisation processes. Inspired by the concept of bioactive materials for bone repair and regeneration, bioglass and in particular calcium silicate type materials show potential for enamel health benefits and is a growing area of research. © 2014 Elsevier Ltd. All rights reserved.

  12. Quantitative evaluation of the enamel caries which were treated with ...

    African Journals Online (AJOL)

    Objectives: The aim of this in vivo study was to quantitatively evaluate the remineralization of the enamel caries on smooth and occlusal surfaces using DIAGNOdent, after daily application of casein phosphopeptide‑amorphous calcium fluoride phosphate (CPP‑ACFP). Materials and Methods: Thirty volunteers, aged 18–30 ...

  13. Human and bovine enamel erosion under 'single-drink' conditions

    NARCIS (Netherlands)

    White, Andrew J.; Yorath, Celyn; ten Hengel, Valerie; Leary, Sam D.; Huysmans, Marie-Charlotte D. N. J. M.; Barbour, Michele E.

    2010-01-01

    Tooth-surface pH is lowered, during drinking, to a value close to the pH of the drink itself. After the drink is swallowed, the pH rises to baseline values but this process can take several minutes. Few techniques can quantify enamel erosion at timescales representative of single drinks. The

  14. Argon laser induced changes to the carbonate content of enamel

    International Nuclear Information System (INIS)

    Ziglo, M.J.; Nelson, A.E.; Heo, G.; Major, P.W.

    2009-01-01

    Argon laser irradiation can be used to cure orthodontic brackets onto teeth in significantly less time than conventional curing lights. In addition, it has been shown that the argon laser seems to impart a demineralization resistance to the enamel. The purpose of this study was to use surface science techniques to ascertain if this demineralization resistance is possibly a result of a decrease in the carbonate content of enamel. Eleven mandibular third molars previously scheduled for extraction were collected and used in the present study. The teeth were sectioned in two and randomly assigned to either the argon laser (457-502 nm; 250 mW cm -2 ) or the control (no treatment) group. The sections assigned to the argon laser group were cured for 10 s and analyzed. To exaggerate any potential changes the experimental sections were then exposed to a further 110 s of argon laser irradiation. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results showed no statistically significant change in the carbonate content of enamel after argon laser irradiation (p > 0.05). Thus, it is suggested that any demineralization resistance imparted to the enamel surface by argon laser irradiation is not due to alterations in carbonate content.

  15. Argon laser induced changes to the carbonate content of enamel

    Energy Technology Data Exchange (ETDEWEB)

    Ziglo, M.J. [Orthodontic Graduate Program, Faculty of Medicine and Dentistry, University of Alberta, Private Practice, Regina, Saskatchewan (Canada); Nelson, A.E., E-mail: aenelson@dow.com [Department of Chemical and Materials Engineering, Faculty of Engineering, University of Alberta (Canada); Heo, G.; Major, P.W. [Orthodontic Graduate Program, Faculty of Medicine and Dentistry, University of Alberta (Canada)

    2009-05-15

    Argon laser irradiation can be used to cure orthodontic brackets onto teeth in significantly less time than conventional curing lights. In addition, it has been shown that the argon laser seems to impart a demineralization resistance to the enamel. The purpose of this study was to use surface science techniques to ascertain if this demineralization resistance is possibly a result of a decrease in the carbonate content of enamel. Eleven mandibular third molars previously scheduled for extraction were collected and used in the present study. The teeth were sectioned in two and randomly assigned to either the argon laser (457-502 nm; 250 mW cm{sup -2}) or the control (no treatment) group. The sections assigned to the argon laser group were cured for 10 s and analyzed. To exaggerate any potential changes the experimental sections were then exposed to a further 110 s of argon laser irradiation. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results showed no statistically significant change in the carbonate content of enamel after argon laser irradiation (p > 0.05). Thus, it is suggested that any demineralization resistance imparted to the enamel surface by argon laser irradiation is not due to alterations in carbonate content.

  16. Argon laser induced changes to the carbonate content of enamel

    Science.gov (United States)

    Ziglo, M. J.; Nelson, A. E.; Heo, G.; Major, P. W.

    2009-05-01

    Argon laser irradiation can be used to cure orthodontic brackets onto teeth in significantly less time than conventional curing lights. In addition, it has been shown that the argon laser seems to impart a demineralization resistance to the enamel. The purpose of this study was to use surface science techniques to ascertain if this demineralization resistance is possibly a result of a decrease in the carbonate content of enamel. Eleven mandibular third molars previously scheduled for extraction were collected and used in the present study. The teeth were sectioned in two and randomly assigned to either the argon laser (457-502 nm; 250 mW cm -2) or the control (no treatment) group. The sections assigned to the argon laser group were cured for 10 s and analyzed. To exaggerate any potential changes the experimental sections were then exposed to a further 110 s of argon laser irradiation. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results showed no statistically significant change in the carbonate content of enamel after argon laser irradiation ( p > 0.05). Thus, it is suggested that any demineralization resistance imparted to the enamel surface by argon laser irradiation is not due to alterations in carbonate content.

  17. Diffusion of calcium and fluride ions in bovine enamel

    NARCIS (Netherlands)

    Flim, Gerrit Jan

    1976-01-01

    This thesis deals with the diffusion of calcium and fluoride ions in bovine enamel, Special attention was given to the mechanism of this diffusion, The experiments were carried out with radioactive labeled ions. The information obtained is relevant with respect to de- and remineralization processes

  18. Microtensile bond strength to enamel affected by hypoplastic amelogenesis imperfecta.

    Science.gov (United States)

    Yaman, Batu Can; Ozer, Fusun; Cabukusta, Cigdem Sozen; Eren, Meltem M; Koray, Fatma; Blatz, Markus B

    2014-02-01

    This study compared the microtensile bond strengths (μTBS) of two different self-etching (SE) and etchand- rinse (ER) adhesive systems to enamel affected by hypoplastic amelogenesis imperfecta (HPAI) and analyzed the enamel etching patterns created by the two adhesive systems using scanning electron microscopy (SEM). Sixteen extracted HPAI-affected molars were used for the bond strength tests and 2 molars were examined under SEM for etching patterns. The control groups consisted of 12 healthy third molars for μTBS tests and two molars for SEM. Mesial and distal surfaces of the teeth were slightly ground flat. The adhesive systems and composite resin were applied to the flat enamel surfaces according to the manufacturers' instructions. The tooth slabs containing composite resin material on their mesial and distal surfaces were cut in the mesio-distal direction with a slow-speed diamond saw. The slabs were cut again to obtain square, 1-mm-thick sticks. Finally, each stick was divided into halves and placed in the μTBS tester. Bond strength tests were performed at a speed of 0.5 mm/min. Data were analyzed with two-way ANOVA and Tukey's tests. There was no significant difference between the bond strength values of ER and SE adhesives (p > 0.05). However, significant differences were found between HPAI and control groups (p systems provide similar bond strengths to HPAI-affected enamel surfaces.

  19. Micro-indentation fracture behavior of human enamel.

    Science.gov (United States)

    Padmanabhan, Sanosh Kunjalukkal; Balakrishnan, Avinash; Chu, Min-Cheol; Kim, Taik Nam; Cho, Seong Jai

    2010-01-01

    The purpose of this study was to determine the crack resistance behavior (K(R)) of human enamel in relation to its microstructure. Human molar teeth were precision cut, polished and tested using Vickers micro-indentation at different loads ranging from 0.98 to 9.8 N. Five indentation load levels were considered, 20 indentation cracks for each load level were introduced on the surface of the test specimen (10 indentations per tooth) and their variability was evaluated using Weibull statistics and an empirical model. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to analyze the crack morphology and propagation mechanisms involved. The results showed that enamel exhibited increasing cracking resistance (K(R)) with increasing load. It was found that the crack propagation mainly depended on the location and the microstructure it encountered. SEM showed the formation of crack bridges and crack deflection near the indentation crack tip. The crack mode was of Palmqvist type even at larger loads of 9.8 N. This was mainly attributed to the large process zone created by the interwoven lamellar rod like microstructure exhibited by the enamel surface. This study shows that there are still considerable prospects for improving dental ceramics and for mimicking the enamel structure developed by nature.

  20. HeNe-laser light scattering by human dental enamel

    NARCIS (Netherlands)

    Zijp, [No Value; tenBosch, JJ; Groenhuis, RAJ

    1995-01-01

    Knowledge of the optical properties of tooth enamel and an understanding of the origin of these properties are necessary for the development of new optical methods for caries diagnosis and the measurement of tooth color. We measured the scattering intensity functions for HeNe-laser light of 80- to

  1. Composition of enamel pellicle from dental erosion patients.

    Science.gov (United States)

    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 erosion patients (p 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. © 2014 S. Karger AG, Basel.

  2. Spectrally enhanced image resolution of tooth enamel surfaces

    Science.gov (United States)

    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.

  3. The aesthetic and functional properties of enamel coatings on steel

    International Nuclear Information System (INIS)

    Scrinzi, E.; Rossi, S.

    2010-01-01

    In this work, the aesthetic and functional properties of enamelled steel panels were investigated. Enamelling is one of the oldest techniques to protect metallic substrates from corrosive phenomena and to improve the aesthetic aspects. This kind of coating is still up-to-date because of its durability, the possibility of creating different aesthetic effects and the eco-sustainability of the production process. Therefore, these kinds of coatings present a great potential in the field of product design. In this work, the durability and the change in the surface properties of different types of enamels are investigated. Chemical resistance, abrasion resistance and ultraviolet radiation (UV) exposure resistance were studied. To determine the chemical resistance, the samples were immersed in acid and basic solutions. Gloss and colour changes were measured. The falling abrasive test was used to evaluate the abrasion resistance: gloss changes were measured to determine the loss of aesthetic properties, and electrochemical impedance spectroscopy was used to evaluate the loss of protective properties. Gloss and colour changes were measured after 1000 h of UV exposure. Optical microscopy and environmental scanning electron microscopy were used to study the morphology of the damage and correlate it to the gloss and colour changes. All the samples presented good resistance in acid solution and good UV exposure resistance. For the other tests the results varied and were correlated to the characteristics of the enamels in terms of composition, thickness, surface roughness and application technique.

  4. Characterization of glazes, enamels and oxides by XRF

    International Nuclear Information System (INIS)

    Mbarek, Iheb

    2009-01-01

    The purpose of this work is to control the technique of X-ray fluorescence, both in qualitative and quantitative characterization for ceramic glazes, enamels and oxides. it's a recent subject of investigation, its purpose is to discover the presence of toxic substances (Pb, Cd, Sn, As ..) and their quantities if it exists in the manufacturing materials.

  5. Ghost cell lesions

    Directory of Open Access Journals (Sweden)

    E Rajesh

    2015-01-01

    Full Text Available Ghost cells have been a controversy for a long time. Ghost cell is a swollen/enlarged epithelial cell with eosnophilic cytoplasm, but without a nucleus. In routine H and E staining these cells give a shadowy appearance. Hence these cells are also called as shadow cells or translucent cells. The appearance of these cells varies from lesion to lesion involving odontogenic and nonodontogenic lesions. This article review about the origin, nature and significance of ghost cells in different neoplasms.

  6. The efficacy of laser-assisted in-office bleaching and home bleaching on sound and demineralized enamel

    Science.gov (United States)

    Akbari, Majid; Mohammadpour, Sakineh

    2015-01-01

    Aims: This study investigated the effectiveness of laser-assisted in-office bleaching and home-bleaching in sound and demineralized enamel. Materials and Methods: The sample consisted of 120 freshly-extracted bovine incisors. Half of the specimens were stored in a demineralizing solution to induce white spot lesions. Following exposure to a tea solution for 7.5 days, the specimens were randomly assigned to 4 groups of 30 according to the type of enamel and the bleaching procedure employed. Groups 1 and 2 consisted of demineralized teeth subjected to in-office bleaching and home bleaching, whereas in groups 3 and 4, sound teeth were subjected to in-office and home bleaching, respectively. A diode laser (810 nm, 2 W, continuous wave, four times for 15 seconds each) was employed for assisting the in-office process. The color of the specimens was measured before (T1) and after (T2) staining and during (T3) and after (T4) the bleaching procedures using a spectrophotometer. The color change (ΔE) between different treatments stages was compared among the groups. Results: There were significant differences in the color change between T2 and T3 (ΔE T2–T3) and T2 and T4 (ΔE T2–T4) stages among the study groups (pbleaching (group 1) as compared to the other groups (Pbleaching could provide faster and greater whitening effect than home bleaching on stained demineralized enamel, but both procedures produced comparable results on sound teeth. PMID:26877590

  7. Intelligent SUBsurface Quality : Intelligent use of subsurface infrastructure for surface quality

    NARCIS (Netherlands)

    Hooimeijer, F.L.; Kuzniecow Bacchin, T.; Lafleur, F.; van de Ven, F.H.M.; Clemens, F.H.L.R.; Broere, W.; Laumann, S.J.; Klaassen, R.G.; Marinetti, C.

    2016-01-01

    This project focuses on the urban renewal of (delta) metropolises and concentrates on the question how to design resilient, durable (subsurface) infrastructure in urban renewal projects using parameters of the natural system – linking in an efficient way (a) water cycle, (b) soil and subsurface

  8. Magnesium stable isotope ecology using mammal tooth enamel

    Science.gov (United States)

    Martin, Jeremy E.; Vance, Derek; Balter, Vincent

    2015-01-01

    Geochemical inferences on ancient diet using bone and enamel apatite rely mainly on carbon isotope ratios (δ13C) and to a lesser extent on strontium/calcium (Sr/Ca) and barium/calcium (Ba/Ca) elemental ratios. Recent developments in nontraditional stable isotopes provide an unprecedented opportunity to use additional paleodietary proxies to disentangle complex diets such as omnivory. Of particular relevance for paleodietary reconstruction are metals present in large quantity in bone and enamel apatite, providing that biologically mediated fractionation processes are constrained. Calcium isotope ratios (δ44Ca) meet these criteria but exhibit complex ecological patterning. Stable magnesium isotope ratios (δ26Mg) also meet these criteria but a comprehensive understanding of its variability awaits new isotopic data. Here, 11 extant mammal species of known ecology from a single locality in equatorial Africa were sampled for tooth enamel and, together with vegetation and feces, analyzed for δ26Mg, δ13C, Sr/Ca, and Ba/Ca ratios. The results demonstrate that δ26Mg incorporated in tooth enamel becomes heavier from strict herbivores to omnivores/faunivores. Using data from experimentally raised sheep, we suggest that this 26Mg enrichment up the trophic chain is due to a 26Mg enrichment in muscle relative to bone. Notably, it is possible to distinguish omnivores from herbivores, using δ26Mg coupled to Ba/Ca ratios. The potential effects of metabolic and dietary changes on the enamel δ26Mg composition remain to be explored but, in the future, multiproxy approaches would permit a substantial refinement of dietary behaviors or enable accurate trophic reconstruction despite specimen-limited sampling, as is often the case for fossil assemblages.

  9. Effects of bleaching agents on human enamel light reflectance.

    Science.gov (United States)

    Markovic, Ljubisa; Fotouhi, Kasra; Lorenz, Heribert; Jordan, Rainer A; Gaengler, Peter; Zimmer, Stefan

    2010-01-01

    Tooth whitening has been associated with splitting-up chromogenic molecules by hydrogen peroxides. Though micromorphological alterations are well documented, little is known about optical changes as a function of shifting in wavelengths. Therefore, the aim of the current study was to measure reflectance changes after bleaching in vitro by using a spectrometer. Forty-eight enamel slabs (diameter = 5 mm) were prepared from the sound enamel of extracted human teeth that were: 1) fully impacted, 2) from juveniles ages 10 to 16 years, 3) from adults 35 to 45 years of age and 4) from seniors older than age 65. In all specimens, the baseline total reflectance measurement was performed with a computer-assisted spectrometer (Ocean Optics, Dunedin, FL, USA) within wavelengths (wl) from 430 nm to 800 nm. Four enamel samples of each age group were exposed to either 10% or 15% carbamide peroxide (Illuminé Home, Dentsply, Konstanz, Germany) or 35% hydrogen peroxide (Pola Office, SDI Limited, Victoria, Australia). After surface treatment, all slabs underwent total reflectance measurement again. Statistical analysis was calculated at wl 450, 500 and 750 nm using the Student's paired t-test and one-way variance analysis. Total reflectance significantly increased after bleaching at all enamel maturation stages, irrespective of the bleaching agent concentration, for wl 450 nm (blue) and 500 nm (green) with penamel from adults and seniors (pwhitening of the dental enamel works at different maturation stages, even in impacted teeth. This effect is irrespective of the bleaching protocol used and the bleaching agent concentration.

  10. THE EFFECT OF IRRADIATION ON ENAMEL MICRO-STRUCTURE CHANGES

    Directory of Open Access Journals (Sweden)

    Harun Gunawan

    2015-06-01

    Full Text Available Radiotherapy plays an important role in the management of head and neck carcinoma therapy. The radiation dose ranges from 40 – 70 Gy, depends on the severity and location of the malignancy. Many patients experience an increased dental caries or sensitivity occurrence following radiotherapy. The objective of this study is to analyze the enamel micro-structure changes after irradiation. Nine polished enamel slabs were prepared from impacted 3rd molars. The slabs were flushed in non-ionic distilled water and dried by using air spray and divided into 3 groups, the control, 20 Gy and 40 Gy irradiation group. Irradiations were performed from Co60 using Gammacell-220E, with duration variables to produce the irradiation doses of 20 and 40 Gy. Philips pW370-XRD was used to examine specimen microstructure changes after irradiation. 1-way ANOVA was used for statistics analysis. It was revealed that grain size after 40 Gy irradiation was 66.29±2.7 nm, and after 20 Gy was 51.64±15.8 whilst 43.95±11.1 nm for the control group. The micro-stain deviation of the 40 Gy group was 0.594±0.15 N/m, and 0.45±2.6 N/m for the 20 Gy group, and 0.378±0.27 N/m for control group. Statistic analysis showed significant grain size differences between 40 Gy compared to both 20 Gy and control groups, but not between 20 Gy compared to the control group. Similarly, there were micro-stain differences between 40 Gy compared to 20 Gy and control groups, but not between 20 Gy compared to control group. It was concluded that irradiation with 40 Gy caused elevation of the enamel microstrain and apaite grainsize. Elevation of the enamel microstrain could lead to enamel crack and gave hypersensitive sensation.

  11. Enamel Bond Strength of New Universal Adhesive Bonding Agents.

    Science.gov (United States)

    McLean, D E; Meyers, E J; Guillory, V L; Vandewalle, K S

    2015-01-01

    Universal bonding agents have been introduced for use as self-etch or etch-and-rinse adhesives depending on the dental substrate and clinician's preference. The purpose of this study was to evaluate the shear bond strength (SBS) of composite to enamel using universal adhesives compared to a self-etch adhesive when applied in self-etch and etch-and-rinse modes over time. Extracted human third molars were used to create 120 enamel specimens. The specimens were ground flat and randomly divided into three groups: two universal adhesives and one self-etch adhesive. Each group was then subdivided, with half the specimens bonded in self-etch mode and half in etch-and-rinse mode. The adhesives were applied as per manufacturers' instructions, and composite was bonded using a standardized mold and cured incrementally. The groups were further divided into two subgroups with 10 specimens each. One subgroup was stored for 24 hours and the second for six months in 37°C distilled water and tested in shear. Failure mode was also determined for each specimen. A three-way analysis of variance (ANOVA) found a significant difference between groups based on bonding agent (p0.05). Clearfil SE in etch-and-rinse and self-etch modes had more mixed fractures than either universal adhesive in either mode. Etching enamel significantly increased the SBS of composite to enamel. Clearfil SE had significantly greater bond strength to enamel than either universal adhesive, which were not significantly different from each other.

  12. Preliminary surface analysis of etched, bleached, and normal bovine enamel

    International Nuclear Information System (INIS)

    Ruse, N.D.; Smith, D.C.; Torneck, C.D.; Titley, K.C.

    1990-01-01

    X-ray photoelectron spectroscopic (XPS) and secondary ion-mass spectroscopic (SIMS) analyses were performed on unground un-pumiced, unground pumiced, and ground labial enamel surfaces of young bovine incisors exposed to four different treatments: (1) immersion in 35% H2O2 for 60 min; (2) immersion in 37% H3PO4 for 60 s; (3) immersion in 35% H2O2 for 60 min, in distilled water for two min, and in 37% H3PO4 for 60 s; (4) immersion in 37% H3PO4 for 60 s, in distilled water for two min, and in 35% H2O2 for 60 min. Untreated unground un-pumiced, unground pumiced, and ground enamel surfaces, as well as synthetic hydroxyapatite surfaces, served as controls for intra-tooth evaluations of the effects of different treatments. The analyses indicated that exposure to 35% H2O2 alone, besides increasing the nitrogen content, produced no other significant change in the elemental composition of any of the enamel surfaces investigated. Exposure to 37% H3PO4, however, produced a marked decrease in calcium (Ca) and phosphorus (P) concentrations and an increase in carbon (C) and nitrogen (N) concentrations in unground un-pumiced specimens only, and a decrease in C concentration in ground specimens. These results suggest that the reported decrease in the adhesive bond strength of resin to 35% H2O2-treated enamel is not caused by a change in the elemental composition of treated enamel surfaces. They also suggest that an organic-rich layer, unaffected by acid-etching, may be present on the unground un-pumiced surface of young bovine incisors. This layer can be removed by thorough pumicing or by grinding. An awareness of its presence is important when young bovine teeth are used in a model system for evaluation of resin adhesiveness

  13. SUBSURFACE REPOSITORY INTEGRATED CONTROL SYSTEM DESIGN

    International Nuclear Information System (INIS)

    C.J. Fernado

    1998-01-01

    The purpose of this document is to develop preliminary high-level functional and physical control system architectures for the proposed subsurface repository at Yucca Mountain. This document outlines overall control system concepts that encompass and integrate the many diverse systems being considered for use within the subsurface repository. This document presents integrated design concepts for monitoring and controlling the diverse set of subsurface operations. The subsurface repository design will be composed of a series of diverse systems that will be integrated to accomplish a set of overall functions and objectives. The subsurface repository contains several Instrumentation and Control (I andC) related systems including: waste emplacement systems, ventilation systems, communication systems, radiation monitoring systems, rail transportation systems, ground control monitoring systems, utility monitoring systems (electrical, lighting, water, compressed air, etc.), fire detection and protection systems, retrieval systems, and performance confirmation systems. Each of these systems involve some level of I andC and will typically be integrated over a data communication network. The subsurface I andC systems will also integrate with multiple surface-based site-wide systems such as emergency response, health physics, security and safeguards, communications, utilities and others. The scope and primary objectives of this analysis are to: (1) Identify preliminary system level functions and interface needs (Presented in the functional diagrams in Section 7.2). (2) Examine the overall system complexity and determine how and on what levels these control systems will be controlled and integrated (Presented in Section 7.2). (3) Develop a preliminary subsurface facility-wide design for an overall control system architecture, and depict this design by a series of control system functional block diagrams (Presented in Section 7.2). (4) Develop a series of physical architectures

  14. SUBSURFACE REPOSITORY INTEGRATED CONTROL SYSTEM DESIGN

    Energy Technology Data Exchange (ETDEWEB)

    C.J. Fernado

    1998-09-17

    The purpose of this document is to develop preliminary high-level functional and physical control system architectures for the proposed subsurface repository at Yucca Mountain. This document outlines overall control system concepts that encompass and integrate the many diverse systems being considered for use within the subsurface repository. This document presents integrated design concepts for monitoring and controlling the diverse set of subsurface operations. The subsurface repository design will be composed of a series of diverse systems that will be integrated to accomplish a set of overall functions and objectives. The subsurface repository contains several Instrumentation and Control (I&C) related systems including: waste emplacement systems, ventilation systems, communication systems, radiation monitoring systems, rail transportation systems, ground control monitoring systems, utility monitoring systems (electrical, lighting, water, compressed air, etc.), fire detection and protection systems, retrieval systems, and performance confirmation systems. Each of these systems involve some level of I&C and will typically be integrated over a data communication network. The subsurface I&C systems will also integrate with multiple surface-based site-wide systems such as emergency response, health physics, security and safeguards, communications, utilities and others. The scope and primary objectives of this analysis are to: (1) Identify preliminary system level functions and interface needs (Presented in the functional diagrams in Section 7.2). (2) Examine the overall system complexity and determine how and on what levels these control systems will be controlled and integrated (Presented in Section 7.2). (3) Develop a preliminary subsurface facility-wide design for an overall control system architecture, and depict this design by a series of control system functional block diagrams (Presented in Section 7.2). (4) Develop a series of physical architectures that

  15. Bonding brackets on white spot lesions pretreated by means of two methods

    Directory of Open Access Journals (Sweden)

    Julia Sotero Vianna

    2016-04-01

    Full Text Available Abstract Objective: The aim of this study was to evaluate the shear bond strength (SBS of brackets bonded to demineralized enamel pretreated with low viscosity Icon Infiltrant resin (DMG and glass ionomer cement (Clinpro XT Varnish, 3M Unitek with and without aging. Methods: A total of 75 bovine enamel specimens were allocated into five groups (n = 15. Group 1 was the control group in which the enamel surface was not demineralized. In the other four groups, the surfaces were submitted to cariogenic challenge and white spot lesions were treated. Groups 2 and 3 were treated with Icon Infiltrant resin; Groups 4 and 5, with Clinpro XT Varnish. After treatment, Groups 3 and 5 were artificially aged. Brackets were bonded with Transbond XT adhesive system and SBS was evaluated by means of a universal testing machine. Statistical analysis was performed by one-way analysis of variance followed by Tukey post-hoc test. Results: All groups tested presented shear bond strengths similar to or higher than the control group. Specimens of Group 4 had significantly higher shear bond strength values (p < 0.05 than the others. Conclusion: Pretreatment of white spot lesions, with or without aging, did not decrease the SBS of brackets.

  16. A Fourth KLK4 Mutation Is Associated with Enamel Hypomineralisation and Structural Abnormalities

    Directory of Open Access Journals (Sweden)

    Claire E. L. Smith

    2017-05-01

    Full Text Available “Amelogenesis imperfecta” (AI describes a group of genetic conditions that result in defects in tooth enamel formation. Mutations in many genes are known to cause AI, including the gene encoding the serine protease, kallikrein related peptidase 4 (KLK4, expressed during the maturation stage of amelogenesis. In this study we report the fourth KLK4 mutation to be identified in autosomal recessively-inherited hypomaturation type AI, c.632delT, p.(L211Rfs*37 (NM_004917.4, NP_004908.4. This homozygous variant was identified in five Pakistani AI families and is predicted to result in a transcript with a premature stop codon that escapes nonsense mediated decay. However, the protein may misfold, as three of six disulphide bonds would be disrupted, and may be degraded or non-functional as a result. Primary teeth were obtained from one affected individual. The enamel phenotype was characterized using high-resolution computerized X-ray tomography (CT, scanning electron microscopy (SEM, energy dispersive X-ray spectroscopy (EDX, and microhardness testing (MH. Enamel from the affected individual (referred to as KLK4 enamel was hypomineralised in comparison with matched control enamel. Furthermore, KLK4 inner enamel was hypomineralised compared with KLK4 outer enamel. SEM showed a clear structural demarcation between KLK4 inner and outer enamel, although enamel structure was similar to control tissue overall. EDX showed that KLK4 inner enamel contained less calcium and phosphorus and more nitrogen than control inner enamel and KLK4 outer enamel. MH testing showed that KLK4 inner enamel was significantly softer than KLK4 outer enamel (p < 0.001. However, the hardness of control inner enamel was not significantly different to that of control outer enamel. Overall, these findings suggest that the KLK4 c.632delT mutation may be a common cause of autosomal recessive AI in the Pakistani population. The phenotype data obtained mirror findings in the Klk4

  17. Subsurface barrier verification technologies, informal report

    International Nuclear Information System (INIS)

    Heiser, J.H.

    1994-06-01

    One of the more promising remediation options available to the DOE waste management community is subsurface barriers. Some of the uses of subsurface barriers include surrounding and/or containing buried waste, as secondary confinement of underground storage tanks, to direct or contain subsurface contaminant plumes and to restrict remediation methods, such as vacuum extraction, to a limited area. To be most effective the barriers should be continuous and depending on use, have few or no breaches. A breach may be formed through numerous pathways including: discontinuous grout application, from joints between panels and from cracking due to grout curing or wet-dry cycling. The ability to verify barrier integrity is valuable to the DOE, EPA, and commercial sector and will be required to gain full public acceptance of subsurface barriers as either primary or secondary confinement at waste sites. It is recognized that no suitable method exists for the verification of an emplaced barrier's integrity. The large size and deep placement of subsurface barriers makes detection of leaks challenging. This becomes magnified if the permissible leakage from the site is low. Detection of small cracks (fractions of an inch) at depths of 100 feet or more has not been possible using existing surface geophysical techniques. Compounding the problem of locating flaws in a barrier is the fact that no placement technology can guarantee the completeness or integrity of the emplaced barrier. This report summarizes several commonly used or promising technologies that have been or may be applied to in-situ barrier continuity verification

  18. Subsurface Science Program Bibliography, 1985--1992

    International Nuclear Information System (INIS)

    1992-08-01

    The Subsurface Science Program sponsors long-term basic research on (1) the fundamental physical, chemical, and biological mechanisms that control the reactivity, mobilization, stability, and transport of chemical mixtures in subsoils and ground water; (2) hydrogeology, including the hydraulic, microbiological, and geochemical properties of the vadose and saturated zones that control contaminant mobility and stability, including predictive modeling of coupled hydraulic-geochemical-microbial processes; and (3) the microbiology of deep sediments and ground water. TWs research, focused as it is on the natural subsurface environments that are most significantly affected by the more than 40 years of waste generation and disposal at DOE sites, is making important contributions to cleanup of DOE sites. Past DOE waste-disposal practices have resulted in subsurface contamination at DOE sites by unique combinations of radioactive materials and organic and inorganic chemicals (including heavy metals), which make site cleanup particularly difficult. The long- term (10- to 30-year) goal of the Subsurface Science Program is to provide a foundation of fundamental knowledge that can be used to reduce environmental risks and to provide a sound scientific basis for cost-effective cleanup strategies. The Subsurface Science Program is organized into nine interdisciplinary subprograms, or areas of basic research emphasis. The subprograms currently cover the areas of Co-Contaminant Chemistry, Colloids/Biocolloids, Multiphase Fluid Flow, Biodegradation/ Microbial Physiology, Deep Microbiology, Coupled Processes, Field-Scale (Natural Heterogeneity and Scale), and Environmental Science Research Center

  19. Subsurface Shielding Source Term Specification Calculation

    International Nuclear Information System (INIS)

    S.Su

    2001-01-01

    The purpose of this calculation is to establish appropriate and defensible waste-package radiation source terms for use in repository subsurface shielding design. This calculation supports the shielding design for the waste emplacement and retrieval system, and subsurface facility system. The objective is to identify the limiting waste package and specify its associated source terms including source strengths and energy spectra. Consistent with the Technical Work Plan for Subsurface Design Section FY 01 Work Activities (CRWMS M and O 2001, p. 15), the scope of work includes the following: (1) Review source terms generated by the Waste Package Department (WPD) for various waste forms and waste package types, and compile them for shielding-specific applications. (2) Determine acceptable waste package specific source terms for use in subsurface shielding design, using a reasonable and defensible methodology that is not unduly conservative. This calculation is associated with the engineering and design activity for the waste emplacement and retrieval system, and subsurface facility system. The technical work plan for this calculation is provided in CRWMS M and O 2001. Development and performance of this calculation conforms to the procedure, AP-3.12Q, Calculations

  20. Camel molar tooth enamel response to gamma rays using EPR spectroscopy.

    Science.gov (United States)

    El-Faramawy, N A; El-Somany, I; Mansour, A; Maghraby, A M; Eissa, H; Wieser, A

    2018-03-01

    Tooth enamel samples from molar teeth of camel were prepared using a combined procedure of mechanical and chemical tooth treatment. Based on electron paramagnetic resonance (EPR) spectroscopy, the dose response of tooth enamel samples was examined and compared to that of human enamel. The EPR dose response of the tooth enamel samples was obtained through irradiation to gamma doses from 1 Gy up to 100 kGy. It was found that the radiation-induced EPR signal increased linearly with gamma dose for all studied tooth enamel samples, up to about 15 kGy. At higher doses, the dose response curve leveled off. The results revealed that the location of the native signal of camel tooth enamel was similar to that of enamel from human molars at 2.00644, but different from that of enamel from cows and goats. In addition, the peak-to-peak width (ΔH pp ) for human and camel molar teeth was similar. It was also found that the response of camel enamel to gamma radiation was 36% lower than that of human enamel. In conclusion, the results indicate the suitability of camel teeth for retrospective gamma dosimetry.

  1. Synchrotron radiation microbeam X-ray fluorescence analysis of zinc concentration in remineralized enamel in situ.

    Science.gov (United States)

    Matsunaga, Tsunenori; Ishizaki, Hidetaka; Tanabe, Shuji; Hayashi, Yoshihiko

    2009-05-01

    Remineralization is an indispensable phenomenon during the natural healing process of enamel decay. The incorporation of zinc (Zn) into enamel crystal could accelerate this remineralization. The present study was designed to investigate the concentration and distribution of Zn in remineralized enamel after gum chewing. The experiment was performed at the Photon Factory. Synchrotron radiation was monochromatized and X-rays were focused into a small beam spot. The X-ray fluorescence (XRF) from the sample was detected with a silicon (Si) (lithium (Li)) detector. X-ray beam energy was tuned to detect Zn. The examined samples were small enamel fragments remineralized after chewing calcium phosphate-containing gum in situ. The incorporation of Zn atom into hydroxyapatite (OHAP), the main component of enamel, was measured using Zn K-edge extended X-ray absorption fine structure (EXAFS) with fluorescence mode at the SPring-8. A high concentration of Zn was detected in a superficial area 10-microm deep of the sectioned enamel after gum chewing. This concentration increased over that in the intact enamel. The atomic distance between Zn and O in the enamel was calculated using the EXAFS data. The analyzed atomic distances between Zn and O in two sections were 0.237 and 0.240 nm. The present experiments suggest that Zn is effectively incorporated into remineralized enamel through the physiological processes of mineral deposition in the oral cavity through gum-chewing and that Zn substitution probably occurred at the calcium position in enamel hydroxyapatite.

  2. Camel molar tooth enamel response to gamma rays using EPR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    El-Faramawy, N.A.; El-Somany, I. [Ain Shams University, Physics Department, Faculty of Science, Cairo (Egypt); Mansour, A. [National Center for Radiation Research and Technology, Atomic Energy Authority, Cairo (Egypt); Maghraby, A.M.; Eissa, H. [National Institute of Standards (NIS), Ionizing Radiation Metrology Laboratory, Giza (Egypt); Wieser, A. [Helmholtz Zentrum Muenchen-German Research Center for Environmental Health, Department of Radiation Sciences, Institute of Radiation Protection, Neuherberg (Germany)

    2018-03-15

    Tooth enamel samples from molar teeth of camel were prepared using a combined procedure of mechanical and chemical tooth treatment. Based on electron paramagnetic resonance (EPR) spectroscopy, the dose response of tooth enamel samples was examined and compared to that of human enamel. The EPR dose response of the tooth enamel samples was obtained through irradiation to gamma doses from 1 Gy up to 100 kGy. It was found that the radiation-induced EPR signal increased linearly with gamma dose for all studied tooth enamel samples, up to about 15 kGy. At higher doses, the dose response curve leveled off. The results revealed that the location of the native signal of camel tooth enamel was similar to that of enamel from human molars at 2.00644, but different from that of enamel from cows and goats. In addition, the peak-to-peak width (ΔH{sub pp}) for human and camel molar teeth was similar. It was also found that the response of camel enamel to gamma radiation was 36% lower than that of human enamel. In conclusion, the results indicate the suitability of camel teeth for retrospective gamma dosimetry. (orig.)

  3. Heat Transfer Behavior across the Dentino-Enamel Junction in the Human Tooth.

    Directory of Open Access Journals (Sweden)

    Lin Niu

    Full Text Available During eating, the teeth usually endure the sharply temperature changes because of different foods. It is of importance to investigate the heat transfer and heat dissipation behavior of the dentino-enamel junction (DEJ of human tooth since dentine and enamel have different thermophysical properties. The spatial and temporal temperature distributions on the enamel, dentine, and pulpal chamber of both the human tooth and its discontinuous boundaries, were measured using infrared thermography using a stepped temperature increase on the outer boundary of enamel crowns. The thermal diffusivities for enamel and dentine were deduced from the time dependent temperature change at the enamel and dentine layers. The thermal conductivities for enamel and dentine were calculated to be 0.81 Wm-1K-1 and 0.48 Wm-1K-1 respectively. The observed temperature discontinuities across the interfaces between enamel, dentine and pulp-chamber layers were due to the difference of thermal conductivities at interfaces rather than to the phase transformation. The temperature gradient distributes continuously across the enamel and dentine layers and their junction below a temperature of 42°C, whilst a negative thermal resistance is observed at interfaces above 42°C. These results suggest that the microstructure of the dentin-enamel junction (DEJ junction play an important role in tooth heat transfer and protects the pulp from heat damage.

  4. Lesion activity assessment

    DEFF Research Database (Denmark)

    Ekstrand, K R; Zero, D T; Martignon, S

    2009-01-01

    in response to cariogenic plaque as well as lesion arrest. Based on this understanding, different clinical scoring systems have been developed to assess the severity/depth and activity of lesions. A recent system has been devised by the International Caries Detection and Assessment System Committee...

  5. Subsurface Contaminants Focus Area annual report 1997

    International Nuclear Information System (INIS)

    1997-01-01

    In support of its vision for technological excellence, the Subsurface Contaminants Focus Area (SCFA) has identified three strategic goals. The three goals of the SCFA are: Contain and/or stabilize contamination sources that pose an imminent threat to surface and ground waters; Delineate DNAPL contamination in the subsurface and remediate DNAPL-contaminated soils and ground water; and Remove a full range of metal and radionuclide contamination in soils and ground water. To meet the challenges of remediating subsurface contaminants in soils and ground water, SCFA funded more than 40 technologies in fiscal year 1997. These technologies are grouped according to the following product lines: Dense Nonaqueous-Phase Liquids; Metals and Radionuclides; Source Term Containment; and Source Term Remediation. This report briefly describes the SCFA 1997 technologies and showcases a few key technologies in each product line

  6. Complete Subsurface Elemental Composition Measurements With PING

    Science.gov (United States)

    Parsons, A. M.

    2012-01-01

    The Probing In situ with Neutrons and Gamma rays (PING) instrument will measure the complete bulk elemental composition of the subsurface of Mars as well as any other solid planetary body. PING can thus be a highly effective tool for both detailed local geochemistry science investigations and precision measurements of Mars subsurface reSOurces in preparation for future human exploration. As such, PING is thus fully capable of meeting a majority of both ncar and far term elements in Challenge #1 presented for this conference. Measuring the ncar subsurface composition of Mars will enable many of the MEPAG science goals and will be key to filling an important Strategic Knowledge Gap with regard to In situ Resources Utilization (ISRU) needs for human exploration. [1, 2] PING will thus fill an important niche in the Mars Exploration Program.

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

    Science.gov (United States)

    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.

  8. Improving the biodegradative capacity of subsurface bacteria

    International Nuclear Information System (INIS)

    Romine, M.F.; Brockman, F.J.

    1993-04-01

    The continual release of large volumes of synthetic materials into the environment by agricultural and industrial sources over the last few decades has resulted in pollution of the subsurface environment. Cleanup has been difficult because of the relative inaccessibility of the contaminants caused by their wide dispersal in the deep subsurface, often at low concentrations and in large volumes. As a possible solution for these problems, interest in the introduction of biodegradative bacteria for in situ remediation of these sites has increased greatly in recent years (Timmis et al. 1988). Selection of biodegradative microbes to apply in such cleanup is limited to those strains that can survive among the native bacterial and predator community members at the particular pH, temperature, and moisture status of the site (Alexander, 1984). The use of microorganisms isolated from subsurface environments would be advantageous because the organisms are already adapted to the subsurface conditions. The options are further narrowed to strains that are able to degrade the contaminant rapidly, even in the presence of highly recalcitrant anthropogenic waste mixtures, and in conditions that do not require addition of further toxic compounds for the expression of the biodegradative capacity (Sayler et al. 1990). These obstacles can be overcome by placing the genes of well-characterized biodegradative enzymes under the control of promoters that can be regulated by inexpensive and nontoxic external factors and then moving the new genetic constructs into diverse groups of subsurface microbes. ne objective of this research is to test this hypothesis by comparing expression of two different toluene biodegradative enzymatic pathways from two different regulatable promoters in a variety of subsurface isolates

  9. MSTS - Multiphase Subsurface Transport Simulator theory manual

    International Nuclear Information System (INIS)

    White, M.D.; Nichols, W.E.

    1993-05-01

    The US Department of Energy, through the Yucca Mountain Site Characterization Project Office, has designated the Yucca Mountain site in Nevada for detailed study as the candidate US geologic repository for spent nuclear fuel and high-level radioactive waste. Site characterization will determine the suitability of the Yucca Mountain site for the potential waste repository. If the site is determined suitable, subsequent studies and characterization will be conducted to obtain authorization from the Nuclear Regulatory Commission to construct the potential waste repository. A principal component of the characterization and licensing processes involves numerically predicting the thermal and hydrologic response of the subsurface environment of the Yucca Mountain site to the potential repository over a 10,000-year period. The thermal and hydrologic response of the subsurface environment to the repository is anticipated to include complex processes of countercurrent vapor and liquid migration, multiple-phase heat transfer, multiple-phase transport, and geochemical reactions. Numerical simulators based on mathematical descriptions of these subsurface phenomena are required to make numerical predictions of the thermal and hydrologic response of the Yucca Mountain subsurface environment The engineering simulator called the Multiphase Subsurface Transport Simulator (MSTS) was developed at the request of the Yucca Mountain Site Characterization Project Office to produce numerical predictions of subsurface flow and transport phenomena at the potential Yucca Mountain site. This document delineates the design architecture and describes the specific computational algorithms that compose MSTS. Details for using MSTS and sample problems are given in the open-quotes User's Guide and Referenceclose quotes companion document

  10. Heating systems for heating subsurface formations

    Science.gov (United States)

    Nguyen, Scott Vinh [Houston, TX; Vinegar, Harold J [Bellaire, TX

    2011-04-26

    Methods and systems for heating a subsurface formation are described herein. A heating system for a subsurface formation includes a sealed conduit positioned in an opening in the formation and a heat source. The sealed conduit includes a heat transfer fluid. The heat source provides heat to a portion of the sealed conduit to change phase of the heat transfer fluid from a liquid to a vapor. The vapor in the sealed conduit rises in the sealed conduit, condenses to transfer heat to the formation and returns to the conduit portion as a liquid.

  11. Subsurface clade of Geobacteraceae that predominates in a diversity of Fe(III)-reducing subsurface environments

    Science.gov (United States)

    Holmes, Dawn E.; O'Neil, Regina A.; Vrionis, Helen A.; N'Guessan, Lucie A.; Ortiz-Bernad, Irene; Larrahondo, Maria J.; Adams, Lorrie A.; Ward, Joy A.; Nicoll , Julie S.; Nevin, Kelly P.; Chavan, Milind A.; Johnson, Jessica P.; Long, Philip E.; Lovely, Derek R.

    2007-01-01

    There are distinct differences in the physiology of Geobacter species available in pure culture. Therefore, to understand the ecology of Geobacter species in subsurface environments, it is important to know which species predominate. Clone libraries were assembled with 16S rRNA genes and transcripts amplified from three subsurface environments in which Geobacter species are known to be important members of the microbial community: (1) a uranium-contaminated aquifer located in Rifle, CO, USA undergoing in situ bioremediation; (2) an acetate-impacted aquifer that serves as an analog for the long-term acetate amendments proposed for in situ uranium bioremediation and (3) a petroleum-contaminated aquifer in which Geobacter species play a role in the oxidation of aromatic hydrocarbons coupled with the reduction of Fe(III). The majority of Geobacteraceae 16S rRNA sequences found in these environments clustered in a phylogenetically coherent subsurface clade, which also contains a number of Geobacter species isolated from subsurface environments. Concatamers constructed with 43 Geobacter genes amplified from these sites also clustered within this subsurface clade. 16S rRNA transcript and gene sequences in the sediments and groundwater at the Rifle site were highly similar, suggesting that sampling groundwater via monitoring wells can recover the most active Geobacter species. These results suggest that further study of Geobacter species in the subsurface clade is necessary to accurately model the behavior of Geobacter species during subsurface bioremediation of metal and organic contaminants.

  12. Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

    Energy Technology Data Exchange (ETDEWEB)

    Yasuhiro, Matsuda, E-mail: matsuda@den.hokudai.ac.jp [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Katsushi, Okuyama [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Hiroko, Yamamoto [Graduate School of Dentistry, Osaka University (Japan); Hisanori, Komatsu [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan); Masashi, Koka; Takahiro, Sato [Takasaki Advanced Radiation Research Institute, JAEA (Japan); Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano [Department of Restorative Dentistry, Graduate School of Dental Medicine Hokkaido University (Japan)

    2015-04-01

    To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials [“MS coats F” (MSF)] and fluoride-free sealing materials (“hybrid coats 2” [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8–4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries.

  13. Fluorine uptake into the human enamel surface from fluoride-containing sealing materials during cariogenic pH cycling

    International Nuclear Information System (INIS)

    Yasuhiro, Matsuda; Katsushi, Okuyama; Hiroko, Yamamoto; Hisanori, Komatsu; Masashi, Koka; Takahiro, Sato; Naoki, Hashimoto; Saiko, Oki; Chiharu, Kawamoto; Hidehiko, Sano

    2015-01-01

    To prevent the formation of caries and reduce dentin hypersensitivity, sealing materials, either with or without fluoride, are generally applied on the tooth in clinical practice. Application of fluoride-free sealing materials results in the formation of an acid-resistant layer on the tooth surface. On the other hand, fluoride-containing sealing materials might not only form an acid-resistant layer but could possibly further provide fluoride to enhance remineralization and reduce demineralization. In this study, the demineralization prevention ability and fluorine uptake rate in human enamel of fluoride-containing sealing materials [“MS coats F” (MSF)] and fluoride-free sealing materials (“hybrid coats 2” [HI]) were evaluated using an automatic pH cycling system. Each material was applied to the original tooth surface, the cut surfaces were covered with sticky wax, and the automatic pH-cycling system simulated daily acid changes (pH 6.8–4.5) occurring in the oral cavity for 4 weeks. Caries progression was analyzed using transverse microradiography (TMR) taken pre and post the 4 weeks of pH cycling. The fluorine and calcium distributions in the carious lesion in each specimen were evaluated using the proton-induced gamma emission (PIGE) and proton-induced X-ray (PIXE) techniques, respectively. TMR analysis showed that both MSF and HI had a caries-preventing effect after 4 weeks of pH cycling. PIGE/PIXE analysis demonstrated that only MSF resulted in fluoride uptake in the enamel surface. Therefore, MSF can help to form an acid-resistant layer and provide fluoride to the enamel surface. The presence of fluoride on the enamel surface suggested that MSF could prevent demineralization, even if the acid-resistant layer was removed, in clinical settings. The data obtained using the PIGE and PIXE techniques are useful for understanding the benefits of the use of a fluoride-containing sealing material for preventing caries

  14. Effectiveness of fluoride sealant in the prevention of carious lesions around orthodontic brackets: an OCT evaluation

    Science.gov (United States)

    Pithon, Matheus Melo; Santos, Mariana de Jesus; de Souza, Camilla Andrade; Leão, Jorge César Borges; Braz, Ana Karla Souza; de Araujo, Renato Evangelista; Tanaka, Orlando Motohiro; Oliveira, Dauro Douglas

    2015-01-01

    Abstract Objective: This article aimed to evaluate in vitro the efficiency of Pro Seal fluoride sealant application in the prevention of white spot lesions around orthodontic brackets. Material and Methods: Brackets were bonded to the buccal surface of bovine incisors, and five groups were formed (n = 15) according to the exposure of teeth to oral hygiene substances and the application of enamel sealant: G1 (control), only brushing was performed with 1.450 ppm fluoride; G2 (control) brushing associated with the use of mouthwash with 225 ppm fluoride; G3, only Pro Seal sealant application was performed with 1.000 ppm fluoride; G4 Pro Seal associated with brushing; G5 Pro Seal associated with brushing and mouthwash. Experimental groups alternated between pH cycling and the procedures described. All specimens were kept at a temperature of 37 °C throughout the entire experiment. Both brushing and immersion in solutions were performed within a time interval of one minute, followed by washing in deionized water three times a day for 28 days. Afterwards, an evaluation by Optical Coherence Tomography (OCT) of the spectral type was performed. In each group, a scanning exam of the white spot lesion area (around the sites where brackets were bonded) and depth measurement of carious lesions were performed. Analysis of variance (ANOVA) was applied to determine whether there were significant differences among groups. For post hoc analysis, Tukey test was used. Results: There was statistically significant difference between groups 1 and 2 (p = 0.003), 1 and 3 (p = 0.008), 1 and 4 (p = 0.000) and 1 and 5 (p = 0.000). The group in which only brushing was performed (Group 1) showed deeper enamel lesion. Conclusion: Pro Seal sealant alone or combined with brushing and/or brushing and the use of a mouthwash with fluoride was more effective in protecting enamel, in comparison to brushing alone. PMID:26691968

  15. In vitro demineralization of enamel by orange juice, apple juice, Pepsi Cola and Diet Pepsi Cola.

    Science.gov (United States)

    Grobler, S R; Senekal, P J; Laubscher, J A

    1990-12-01

    Enamel demineralization was studied over periods related to normal use of an orange juice, an apple juice, Pepsi Cola and Diet Pepsi Cola. Rectangular blocks of intact human enamel (3 mm x 3 mm) were cut from teeth, coated with nail varnish except for the enamel surface and exposed to the drinks for 2, 4, 5, 6 or 40 minutes. The amount of calcium released from the enamel into solution was determined with the use of an atomic absorption spectrophotometer. The results showed the following degree of enamel demineralization: Pepsi Cola = orange juice greater than apple juice greater than Diet Pepsi Cola. The results suggest that diet colas are less demineralizing than other acid drinks, and complementary plaque studies indicate that they are also less cariogenic. The study emphasized the importance of acid-type, buffer capacity, pH and the presence of other components on the degree of enamel demineralization.

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

    Energy Technology Data Exchange (ETDEWEB)

    Belikov, A V; Skrypnik, A V; Shatilova, K V [St. Petersburg National Research University of Information Technologies, Mechanics and Optics, St. Petersburg (Russian Federation)

    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)

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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. (laser biophotonics)

  18. Photomechanical model of tooth enamel ablation by Er-laser radiation

    Science.gov (United States)

    Belikov, A. V.; Shatilova, K. V.; Skrypnik, A. V.; Vostryakov, R. G.; Maykapar, N. O.

    2012-03-01

    The photomechanical model of ablation of human tooth enamel is described in this work. It takes into account the structural peculiarities of enamel: free water in the enamel pores or cracks. We consider the photomechanical destruction of the enamel rods of hydroxyapatite by the pressure of water contained in the enamel pores and heated by laser radiation. This model takes into account attenuation by the Lambert-Beer law when radiation passes through the tissue and the fact that the tissue removal occurs when a unit volume of water was heated to the critical temperature. Decreasing logarithmic dependence of the enamel removal efficiency on the energy density was obtained as a result of the calculations. The shape of this function follows the shape of the experimental curve.

  19. Analysis of the enamel hypoplasia using micro-CT scanner versus classical method.

    Science.gov (United States)

    Marchewka, Justyna; Skrzat, Janusz; Wróbel, Andrzej

    2014-01-01

    This article demonstrates the use of micro-CT scanning of the teeth surface for recognizing and evaluating severity of the enamel hypoplasia. To test capabilities of the microtomography versus classical method of evaluation hypoplastic defects of the enamel we selected two human teeth (C, M(2)) showing different types of enamel hypoplasia: linear, pits, and groove. Examined samples derive from archeological material dated on XVII-XVIII AD and excavated in Poland. In the current study we proved that micro-CT scanning is a powerful technique not only for imaging all kinds of the enamel hypoplasia but also allows to perform accurate measurements of the enamel defects. We figure out that contrary to the classical method of scoring enamel defects, the micro-computed tomography yields adequate data which serve for estimating the length of stress episode and length of interval between them.

  20. Retrospective radiation dosimetry using electron paramagnetic resonance in canine dental enamel

    International Nuclear Information System (INIS)

    Khan, Rao F.H.; Pekar, J.; Rink, W.J.; Boreham, D.R.

    2005-01-01

    Electron paramagnetic resonance (EPR) biodosimetry of human tooth enamel has been widely used for measuring radiation doses in various scenarios. We have now developed EPR dosimetry in tooth enamel extracted from canines. Molars and incisors from canines were cleaned by processing in supersaturated aqueous potassium hydroxide solution. The dosimetric signal in canine tooth enamel was found to increase linearly as a function of laboratory added dose from 0.44±0.02 to 4.42±0.22 Gy. The gamma radiation sensitivity of the canine molar enamel was found to be comparable to that of human tooth enamel. The dosimetric signal in canine enamel has been found to be stable up to at least 6 weeks after in vitro irradiation. A dosimetric signal variation of 10-25% was observed for canines ranging from in age 3 years to 16 year old

  1. Comparison Of Bond Strength Of Orthodontic Molar Tubes Using Different Enamel Etching Techniques And Their Effect On Enamel

    International Nuclear Information System (INIS)

    Abd el Rahman, H.Y.

    2013-01-01

    In fixed orthodontic treatment, brackets and tubes are used for transferring orthodontic forces to the teeth. Those attachments were welded to cemented bands. Fifty years ago, direct bonding of brackets and other attachments has become a common technique in fixed orthodontic treatment. Orthodontists used to band teeth, especially molars and second premolars, to avoid the need for re bonding accessories in these regions of heavy masticatory forces. However, it is a known fact that direct bonding saves chair time as it does not require prior band selection and fitting, has the ability to maintain good oral hygiene, improve esthetics and make easier attachment to crowded and partially erupted teeth. Moreover, when the banding procedure is not performed with utmost care it can damage periodontal and/or dental tissues. Molar tubes bonding decreases the chance of decalcification caused by leakage beneath the bands. Since molar teeth are subjected to higher masticatory impact, especially lower molars, it would be convenient to devise methods capable of increasing the efficiency of their traditional bonding. These methods may include variation in bond able molar tube material, design, bonding materials and etching techniques. For achieving successful bonding, the bonding agent must penetrate the enamel surface; have easy clinical use, dimensional stability and enough bond strength. Different etching techniques were introduced in literature to increase the bond strength which includes: conventional acid etching, sandblasting and laser etching techniques. The process of conventional acid etching technique was invented In (1955) as the surface of enamel has great potential for bonding by micromechanical retention, to form ‘the mechanical lock‘. The primary effect of enamel etching is to increase the surface area. However, this roughens the enamel microscopically and results in a greater surface area on which to bond. By dissolving minerals in enamel, etchants remove the

  2. A comparison of orthodontic bracket shear bond strength on enamel deproteinized by 5.25% sodium hypochlorite using total etch and self-etch primer

    Science.gov (United States)

    Ongkowidjaja, F.; Soegiharto, B. M.; Purbiati, M.

    2017-08-01

    The shear bond strength (SBS) can be increased by removing protein pellicles from the enamel surface by deproteinization using 5.25% sodium hypochlorite (NaOCl). The SBS of a self-etch primer is lower than that of a total etch primer; nonetheless, it prevents white spot lesions. This study aimed to assess the SBS of the Anyetch (AE) total etch primer and FL-Bond II Shofu (FL) self-etch primer after enamel deproteinization using 5.25% NaOCl. Forty eight human maxillary first premolars were extracted, cleaned, and divided into four groups. In group A, brackets were bonded to the enamel without deproteinization before etching (A1: 10 teeth using total etch primer (AE); A2: 10 teeth using self-etch primer (FL)). In group B, brackets were bonded to the enamel after deproteinization with 5.25% NaOCl before etching (B1: 10 teeth using total etch primer (AE); B2: 10 teeth using self-etch primer (FL)). Brackets were bonded using Transbond XT, stored in artificial saliva for 24 h at 37°C, mounted on acrylic cylinders, and debonded using a Shimadzu AG-5000 universal testing machine. There were no significant differences in SBS between the total etch (AE) groups (p > 0.05) and between the self-etch (FL) groups (p > 0.05). There were significant differences in SBS between groups A and B. The mean SBS for groups A1, A2, B1, and B2 was 12.91±3.99, 4.46±2.47, 13.06±3.66, and 3.62±2.36 MPa, respectively. Deproteinization using NaOCl did not affect the SBS of the total etch primer (AE) group; it reduced the SBS of the self-etch primer (FL) group, but not with a statistically significant difference.

  3. Intraosseous osteolytic lesions

    Energy Technology Data Exchange (ETDEWEB)

    Adler, C.P.; Wenz, W.

    1981-10-01

    Any pathological damage occurring in a bone will produce either an osteolytic or osteosclerotic lesion which can be seen in the macroscopic specimen as well as in the roentgenogram. Various bone lesions may lead to local destructions of the bone. An osteoma or osteoplastic osteosarcoma produces an osteosclerotic lesion showing a dense mass in the roentgenogram; a chondroblastoma or an osteoclastoma, on the other hand, induces an osteolytic focal lesion. This paper presents examples of different osteolytic lesions of the humerus. An osteolytic lesion seen in the roentgenogram may be either produced by an underlying non-ossifying fibroma of the bone, by fibrous dysplasia, osteomyelitis or Ewing's sarcoma. Differential diagnostic considerations based on the radiological picture include eosinophilic bone granuloma, juvenile or aneurysmal bone cyst, multiple myeloma or bone metastases. Serious differential diagnostic problems may be involved in case of osteolytic lesions occurring in the humerus. Cases of this type involving complications have been reported and include the presence of an teleangiectatic osteosarcoma as well as that of a hemangiosarcoma of the bone.

  4. Dose response of hydrazine - Deproteinated tooth enamel under blue light stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Yuece, Ulkue Rabia, E-mail: ulkuyuce@hotmail.co [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Tandogan - Ankara (Turkey); Meric, Niyazi, E-mail: meric@ankara.edu.t [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Tandogan - Ankara (Turkey); Atakol, Orhan, E-mail: atakol@science.ankara.edu.t [Ankara University, Science Faculty, Department of Chemistry, 06100, Tandogan - Ankara (Turkey); Yasar, Fusun, E-mail: ab121310@adalet.gov.t [Council of Forensic Medicine, Ankara Branch, Ankara (Turkey)

    2010-08-15

    The beta dose response and Optically Stimulated Luminescence (OSL) signal stability characteristics of human tooth enamel deproteinated by hydrazine reagent under blue photon stimulation are reported. Removal of the protein organic component of tooth enamel resulted in a higher OSL sensitivity and slower fading of OSL signals. The effect of chemical sample preparation on the enamel sample sensitivity is discussed and further steps to make this deproteinization treatment suitable for in vitro dose reconstruction studies are suggested.

  5. Dose response of hydrazine - Deproteinated tooth enamel under blue light stimulation

    International Nuclear Information System (INIS)

    Yuece, Ulkue Rabia; Meric, Niyazi; Atakol, Orhan; Yasar, Fusun

    2010-01-01

    The beta dose response and Optically Stimulated Luminescence (OSL) signal stability characteristics of human tooth enamel deproteinated by hydrazine reagent under blue photon stimulation are reported. Removal of the protein organic component of tooth enamel resulted in a higher OSL sensitivity and slower fading of OSL signals. The effect of chemical sample preparation on the enamel sample sensitivity is discussed and further steps to make this deproteinization treatment suitable for in vitro dose reconstruction studies are suggested.

  6. A study on the characteristics of enamel to electron spin resonance spectrum for retrospective dosimetry

    International Nuclear Information System (INIS)

    Hong, Dae Seok; Lee, Kun Jai

    2003-01-01

    Electron Spin Resonance (ESR) spectroscopy is one of the methods applicable to retrospective dosimetry. The retrospective dosimetry is a part of dose reconstruction for estimation of exposed dose occurred years before the estimation. A tooth can be separated as enamel, dentine and cementum. Among the three parts, enamel is known as to show the best sensitivity to the absorbed dose and is most widely used. Since the later 80s, ESR dosimetry with tooth enamel has been studied and applied for the retrospective dosimetry. There are some factors affecting the sensitivity of enamel to absorbed dose. One of the factors is a size of enamel. Grain size of the 1.0mm∼0.1mm range is commonly used and 0.6mm∼0.25mm is recommended in other study. But the sensitivity can be varied by the grain size. In this study, the granular effect of enamel to the sensitivity is examined for application to retrospective dosimetry. In the enamel separation, to minimize the physically induced ESR spectrum, only chemical separation method was used. Separated enamels were divided by their size. The sizes of each sample is 1.0mm∼0.71mm, 0.5mm∼0.3mm, and below 0.1mm, respectively. All enamel samples show ESR spectrum related to the absorbed dose and the ESR spectrum shows linearity to the absorbed dose. The sensitivities are similar for each sample. But the enamel of size below 0.1mm shows poor characteristics relative to other enamel size. So, it is not recommended to use enamel samples below 0.1mm

  7. Effect of a New Surface Treatment Solution on the Bond Strength of Composite to Enamel

    Science.gov (United States)

    2016-06-01

    Bond Strength of Composite to Enamel " is appropriately acknowledged and, beyond brief excerpts, is with the permission of the copyright owner...Solution on the Bond Strength of Composite to Enamel ABSTRACT Clean & Boost (Apex Dental Materials) is a novel surface treatment solution...designed to be used in place of phosphoric acid to increase the bond strength of self-etch adhesives to enamel and more effectively remove contaminants

  8. Spectra processing at tooth enamel dosimetry: Analytical description of EPR spectrum at different microwave power

    International Nuclear Information System (INIS)

    Tieliewuhan, E.; Ivannikov, A.; Zhumadilov, K.; Nalapko, M.; Tikunov, D.; Skvortsov, V.; Stepanenko, V.; Toyoda, S.; Tanaka, K.; Endo, S.; Hoshi, M.

    2006-01-01

    Variation of the electron paramagnetic resonance (EPR) spectrum of the human tooth enamel recorded at different microwave power is investigated. The analytical models describing the native and the radiation-induced signals in the enamel are proposed, which fit the experimental spectra in wide range of microwave power. These models are designed to use for processing the spectra of irradiated enamel at determination of the absorbed dose from the intensity of the radiation-induced signal

  9. Dose-Dependent Rescue of KO Amelogenin Enamel by Transgenes in Vivo.

    Science.gov (United States)

    Bidlack, Felicitas B; Xia, Yan; Pugach, Megan K

    2017-01-01

    Mice lacking amelogenin (KO) have hypoplastic enamel. Overexpression of the most abundant amelogenin splice variant M180 and LRAP transgenes can substantially improve KO enamel, but only ~40% of the incisor thickness is recovered and the prisms are not as tightly woven as in WT enamel. This implies that the compositional complexity of the enamel matrix is required for different aspects of enamel formation, such as organizational structure and thickness. The question arises, therefore, how important the ratio of different matrix components, and in particular amelogenin splice products, is in enamel formation. Can optimal expression levels of amelogenin transgenes representing both the most abundant splice variants and cleavage product at protein levels similar to that of WT improve the enamel phenotype of KO mice? Addressing this question, our objective was here to understand dosage effects of amelogenin transgenes ( Tg ) representing the major splice variants M180 and LRAP and cleavage product CTRNC on enamel properties. Amelogenin KO mice were mated with M180 Tg , CTRNC Tg and LRAP Tg mice to generate M180 Tg and CTRNC Tg double transgene and M180 Tg , CTRNC Tg , LRAP Tg triple transgene mice with transgene hemizygosity (on one allelle) or homozygosity (on both alleles). Transgene homo- vs. hemizygosity was determined by qPCR and relative transgene expression confirmed by Western blot. Enamel volume and mineral density were analyzed by microCT, thickness and structure by SEM, and mechanical properties by Vickers microhardness testing. There were no differences in incisor enamel thickness between amelogenin KO mice with three or two different transgenes, but mice homozygous for a given transgene had significantly thinner enamel than mice hemizygous for the transgene ( p structure, but only up to a maximum of ~80% that of molar and ~40% that of incisor wild-type enamel.

  10. A Comparison of Fatigue Crack Growth in Human Enamel and Hydroxyapatite

    OpenAIRE

    Bajaj, Devendra; Nazari, Ahmad; Eidelman, Naomi; Arola, Dwayne

    2008-01-01

    Cracks and craze lines are often observed in the enamel of human teeth, but they rarely cause tooth fracture. The present study evaluates fatigue crack growth in human enamel, and compares that to the fatigue response of sintered hydroxyapatite (HAp) with similar crystallinity, chemistry and density. Miniature inset compact tension (CT) specimens were prepared that embodied a small piece of enamel (N=8) or HAp (N=6). The specimens were subjected to mode I cyclic loads and the steady state cra...

  11. Using Bonding Enamel-Coated Steel Fixtures to Produce More Durable Brick/Masonry Structures

    Science.gov (United States)

    2010-02-01

    Initial tests with enameled metal straps cracked all the test cylinders and straps would not pull out BUILDING STRONG® New Strong Durable Ties...BUILDING STRONG® Using Bonding Enamel -Coated Steel Fixtures to Produce More Durable Brick/Masonry Structures Principal Investigator: Steven C...COVERED 00-00-2010 to 00-00-2010 4. TITLE AND SUBTITLE Using Bonding Enamel -Coated Steel Fixtures to Produce More Durable Brick/Masonry

  12. Modelling Nitrogen Transformation in Horizontal Subsurface Flow ...

    African Journals Online (AJOL)

    A mathematical model was developed to permit dynamic simulation of nitrogen interaction in a pilot horizontal subsurface flow constructed wetland receiving effluents from primary facultative pond. The system was planted with Phragmites mauritianus, which was provided with root zone depth of 75 cm. The root zone was ...

  13. Electrical resistivity determination of subsurface layers, subsoil ...

    African Journals Online (AJOL)

    Electrical resistivity determination of subsurface layers, subsoil competence and soil corrosivity at and engineering site location in Akungba-Akoko, ... The study concluded that the characteristics of the earth materials in the site would be favourable to normal engineering structures/materials that may be located on it.

  14. Assessment of performance parameters for EPR dosimetry with tooth enamel

    International Nuclear Information System (INIS)

    Wieser, A.; Fattibene, P.; Shishkina, E.A.; Ivanov, D.V.; De Coste, V.; Guettler, A.; Onori, S.

    2008-01-01

    In the framework of a comparison between three laboratories, electron paramagnetic resonance (EPR) signal-to-dose response curves were measured for sets of 30 tooth enamel samples and the variance of EPR measurements in dependence on absorbed dose was evaluated, in nine combinations of laboratory of sample preparation and EPR evaluation, respectively. As a test for benchmarking of EPR evaluation, the parameters 'critical dose' and 'limit of detection' were proposed as performance parameters following definitions from chemical-metrology, and a model function was suggested for analytical formulation of the dependence of the variance of EPR measurement on absorbed dose. First estimates of limits of detection by weighted and unweighted fitting resulted in the range 101-552 and 67-561 mGy, respectively, and were generally larger with weighted than with unweighted fitting. Indication was found for the influence of methodology of sample preparation and applied EPR measurement parameters on performance of EPR dosimetry with tooth enamel

  15. Selective saturation method for EPR dosimetry with tooth enamel

    International Nuclear Information System (INIS)

    Ignatiev, E.A.; Romanyukha, A.A.; Koshta, A.A.; Wieser, A.

    1996-01-01

    The method of selective saturation is based on the difference in the microwave (mw) power dependence of the background and radiation induced EPR components of the tooth enamel spectrum. The subtraction of the EPR spectrum recorded at low mw power from that recorded at higher mw power provides a considerable reduction of the background component in the spectrum. The resolution of the EPR spectrum could be improved 10-fold, however simultaneously the signal-to-noise ratio was found to be reduced twice. A detailed comparative study of reference samples with known absorbed doses was performed to demonstrate the advantage of the method. The application of the selective saturation method for EPR dosimetry with tooth enamel reduced the lower limit of EPR dosimetry to about 100 mGy. (author)

  16. Characterization of enameled glass excavated from Laem Pho, southern Thailand

    Science.gov (United States)

    Dhanmanonda, W.; Won-in, K.; Tancharakorn, S.; Tantanuch, W.; Thongleurm, C.; Kamwanna, T.; Dararutana, P.

    2012-07-01

    Laem Pho in Surat Thani, southern province of Thailand is one of the most important historic site on the eastern shore of the Gulf of Thailand. In this work, the enameled glass fragments which looked-like Islamic glass mainly excavated from this site were analyzed using SEM-EDS, PIXE and μ-XRF, in order to understand the chemical composition by comparing the archaeological data and topology. The structure of the enameled decoration was also studied. The resulting data indicated that high-magnesia alkali-lime silicate glass was produced. The presence of transition metals such as copper, iron and manganese were affected on the glass colorations. Typological classifications, technological observations and comparative studies serve to clarify the development and cultural inter-relationships of various glass objects along the trade and exchange networks in ancient maritime.

  17. Characterization of enameled glass excavated from Laem Pho, southern Thailand

    International Nuclear Information System (INIS)

    Dhanmanonda, W; Won-in, K; Tancharakorn, S; Tantanuch, W; Thongleurm, C; Kamwanna, T; Dararutana, P

    2012-01-01

    Laem Pho in Surat Thani, southern province of Thailand is one of the most important historic site on the eastern shore of the Gulf of Thailand. In this work, the enameled glass fragments which looked-like Islamic glass mainly excavated from this site were analyzed using SEM-EDS, PIXE and μ-XRF, in order to understand the chemical composition by comparing the archaeological data and topology. The structure of the enameled decoration was also studied. The resulting data indicated that high-magnesia alkali-lime silicate glass was produced. The presence of transition metals such as copper, iron and manganese were affected on the glass colorations. Typological classifications, technological observations and comparative studies serve to clarify the development and cultural inter-relationships of various glass objects along the trade and exchange networks in ancient maritime.

  18. Determination of atomic number and composition of human enamel

    International Nuclear Information System (INIS)

    Nogueira, M.S.; Rodas Duran, J.E.

    2001-01-01

    The teeth are organs of complicated structure that consist, partly, of hard tissue containing in its interior the dental pulp, rich in vases and nerves. The main mass of the tooth is constituted by the dentine, which is covered with hard tissues and of epithelial origin called enamel. The dentine of the human teeth used in this work were completely removed and the teeth were cut with a device with a diamond disc. In this work the chemical composition of the human enamel was determined, which showed a high percentage of Ca and P, in agreement with the results found in the literature. The effective atomic number of the material and the half-value layer in the energy range of diagnostic X-ray beams were determined. Teeth could be used to evaluated the public's individual doses as well as for retrospective dosimetry what confirms the importance of their effective atomic number and composition determination. (author)

  19. Treatment of enamel hypoplasia in a patient with Usher syndrome.

    Science.gov (United States)

    de la Peña, Victor Alonso; Valea, Martín Caserío

    2011-08-01

    Usher syndrome (USH) is a group of autosomal recessive diseases characterized by the association of retinitis pigmentosa with sensorineural hearing loss. There are three types of USH. In addition, in people with USH and hypoplasia, the thickness of the enamel is reduced. The authors describe a case of a patient with USH type II associated with severe enamel hypoplasia and multiple unerupted teeth. The authors placed direct composite crowns and extracted severely affected and impacted molars. There is little information available on the oral pathologies of USH. Because the authors did not know how the patient's condition would progress and the patient still was growing, the authors treated the patient conservatively by placing direct composite crowns. The treatment has met both esthetic and functional expectations for 10 years. Copyright © 2011 American Dental Association. All rights reserved.

  20. Fluorine uptake into human enamel around fluoride-containing dental materials during cariogenic pH cycling

    International Nuclear Information System (INIS)

    Komatsu, H.; Yamamoto, H.; Nomachi, M.; Yasuda, K.; Matsuda, Y.; Kinugawa, M.; Kijimura, T.; Sano, H.; Satou, T.; Oikawa, S.; Kamiya, T.

    2009-01-01

    Using PIGE (Proton Induced Gamma Emission) technique at TARRI (Takasaki Advanced Radiation Research Institute), Japan, we measured fluorine (F) uptake into the tooth enamel around two fluoride-containing materials during caries progression using pH cycling. Class V cavities in extracted human teeth were drilled and filled with fluoride-containing materials (i.e. 'Fuji IX' (FN) and 'UniFil flow with MEGA bond' (UF)) and a non-fluoride-containing material (i.e. 'SOLARE with MEGA bond' (SO)). Three 120 μm longitudinal sections including the filling material were obtained from each tooth. In order to simulate daily acid attack occurring in the oral cavity, the pH cycling (pH 6.8-4.5) was carried out for 1, 3 and 5 weeks, separately. After pH cycling, the caries progression in all specimens was observed using transverse microradiography (TMR). The F and calcium distributions of the specimens were evaluated using PIGE and PIXE techniques. The F distribution of the specimens clearly showed the F uptake from FN into enamel adjacent to the filling material, while the F uptakes from UF and SO were not detected. For UF, the MEGA bond (non-fluoride-containing) between the tooth and UniFil flow interfered with the F absorption into the tooth. For FN, the amount of F uptake into the subsurface enamel increased during pH cycling. The amount of F uptake in 5-week pH cycling had significantly higher value compared to those in 1- and 3-week pH cycling. For UF and SO, there were no significant differences between the different durations of pH cycling. Among fluoride-containing materials, there were some differences in the F uptake with increased pH cycling, which could possibly lead to obtaining difference in clinical performance. The data obtained using PIGE and PIXE techniques were useful in understanding the benefit of fluorine by means of fluoride-containing material for preventing caries.

  1. Fluorine uptake into human enamel around fluoride-containing dental materials during cariogenic pH cycling

    Energy Technology Data Exchange (ETDEWEB)

    Komatsu, H. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan)], E-mail: kom@den.hokudai.ac.jp; Yamamoto, H. [Graduate School of Dentistry, Osaka University, 1-8 Yamada-Oka, Suita 565-0871 (Japan); Nomachi, M. [Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka 560-0043 (Japan); Yasuda, K. [The Wakasa wan Energy Research Center, 64-52-1 Hase, Tsuruga 914-0192 (Japan); Matsuda, Y.; Kinugawa, M.; Kijimura, T.; Sano, H. [Graduate School of Dental Medicine, Hokkaido University, Kita-13, Nishi-7, Kita-ku, Sapporo 060-8586 (Japan); Satou, T.; Oikawa, S.; Kamiya, T. [Advanced Radiation Technology, TARRI, JAEA, 1233 Watanuki-machi, Takasaki 370-1292 (Japan)

    2009-06-15

    Using PIGE (Proton Induced Gamma Emission) technique at TARRI (Takasaki Advanced Radiation Research Institute), Japan, we measured fluorine (F) uptake into the tooth enamel around two fluoride-containing materials during caries progression using pH cycling. Class V cavities in extracted human teeth were drilled and filled with fluoride-containing materials (i.e. 'Fuji IX' (FN) and 'UniFil flow with MEGA bond' (UF)) and a non-fluoride-containing material (i.e. 'SOLARE with MEGA bond' (SO)). Three 120 {mu}m longitudinal sections including the filling material were obtained from each tooth. In order to simulate daily acid attack occurring in the oral cavity, the pH cycling (pH 6.8-4.5) was carried out for 1, 3 and 5 weeks, separately. After pH cycling, the caries progression in all specimens was observed using transverse microradiography (TMR). The F and calcium distributions of the specimens were evaluated using PIGE and PIXE techniques. The F distribution of the specimens clearly showed the F uptake from FN into enamel adjacent to the filling material, while the F uptakes from UF and SO were not detected. For UF, the MEGA bond (non-fluoride-containing) between the tooth and UniFil flow interfered with the F absorption into the tooth. For FN, the amount of F uptake into the subsurface enamel increased during pH cycling. The amount of F uptake in 5-week pH cycling had significantly higher value compared to those in 1- and 3-week pH cycling. For UF and SO, there were no significant differences between the different durations of pH cycling. Among fluoride-containing materials, there were some differences in the F uptake with increased pH cycling, which could possibly lead to obtaining difference in clinical performance. The data obtained using PIGE and PIXE techniques were useful in understanding the benefit of fluorine by means of fluoride-containing material for preventing caries.

  2. An exploratory study of human teeth enamel by using Ft-Raman spectroscopy

    International Nuclear Information System (INIS)

    Afishah Alias; Siti Rahayu Mohd Hashim; Mihaly, Judith; Julyannie Wajir; Fauziah Abdul Aziz

    2009-01-01

    Unaffected , affected and heavily affected teeth enamel were studied by using FT-Raman spectroscopy. The 14 permanent teeths enamel surface were measured randomly, resulting in total n = 43 FT-Raman spectra. The results obtained from FT-Raman spectra of heavily affected, affected and unaffected tooths enamel surfaces did not show any significant difference. In this study, Kruskal-Wallis and Wilcoxon rank sum tests were used to compare the intensity between the categories of enamel as well as the surfaces of teeth samples. (author)

  3. Enamel protein regulation and dental and periodontal physiopathology in MSX2 mutant mice.

    Science.gov (United States)

    Molla, Muriel; Descroix, Vianney; Aïoub, Muhanad; Simon, Stéphane; Castañeda, Beatriz; Hotton, Dominique; Bolaños, Alba; Simon, Yohann; Lezot, Frédéric; Goubin, Gérard; Berdal, Ariane

    2010-11-01

    Signaling pathways that underlie postnatal dental and periodontal physiopathology are less studied than those of early tooth development. Members of the muscle segment homeobox gene (Msx) family encode homeoproteins that show functional redundancy during development and are known to be involved in epithelial-mesenchymal interactions that lead to crown morphogenesis and ameloblast cell differentiation. This study analyzed the MSX2 protein during mouse postnatal growth as well as in the adult. The analysis focused on enamel and periodontal defects and enamel proteins in Msx2-null mutant mice. In the epithelial lifecycle, the levels of MSX2 expression and enamel protein secretion were inversely related. Msx2+/- mice showed increased amelogenin expression, enamel thickness, and rod size. Msx2-/- mice displayed compound phenotypic characteristics of enamel defects, related to both enamel-specific gene mutations (amelogenin and enamelin) in isolated amelogenesis imperfecta, and cell-cell junction elements (laminin 5 and cytokeratin 5) in other syndromes. These effects were also related to ameloblast disappearance, which differed between incisors and molars. In Msx2-/- roots, Malassez cells formed giant islands that overexpressed amelogenin and ameloblastin that grew over months. Aberrant expression of enamel proteins is proposed to underlie the regional osteopetrosis and hyperproduction of cellular cementum. These enamel and periodontal phenotypes of Msx2 mutants constitute the first case report of structural and signaling defects associated with enamel protein overexpression in a postnatal context.

  4. Fluoride reactions with dental enamel following different forms of fluoride supply

    International Nuclear Information System (INIS)

    Hellstroem, I.; Ericsson, Y.

    1976-01-01

    The reactions with dental enamel of NaF as tablets dissolved in different beverages or supplied with NaCl, simulating domestic salt fluoridation, were studied in tests with enamel surfaces and enamel powder. It was confirmed that powdered enamel can react quite differently from enamel surfaces under certain conditions. Enamel surfaces took up much more fluoride (F) from orange juice than from water or milk, and neither the low pH nor the citrate content of the juice increased the formation of unstable CaF 2 in the enamel, as judged from a KOH leaching test. The F uptake by enamel surfaces from 0.25 mM NaF in 175 mM NaCl, corresponding to a dish prepared with salt containing 500 parts/10 6 F, was about 80 percent greater than from the same NaF concentration in water. This NaCl concentration did not increase the formation of CaF 2 in the enamel, as judged from the KOH test, while 350 mM NaCl caused a moderate increase. The investigations support the administration of NaF tablets with orange juice and the plans for domestic salt fluoridation. (author)

  5. Circadian Rhythm Regulates Development of Enamel in Mouse Mandibular First Molar

    Science.gov (United States)

    Tao, Jiang; Zhai, Yue; Park, Hyun; Han, Junli; Dong, Jianhui; Xie, Ming; Gu, Ting; Lewi, Keidren; Ji, Fang; Jia, William

    2016-01-01

    Rhythmic incremental growth lines and the presence of melatonin receptors were discovered in tooth enamel, suggesting possible role of circadian rhythm. We therefore hypothesized that circadian rhythm may regulate enamel formation through melatonin receptors. To test this hypothesis, we examined expression of melatonin receptors (MTs) and amelogenin (AMELX), a maker of enamel formation, during tooth germ development in mouse. Using qRT-PCR and immunocytochemistry, we found that mRNA and protein levels of both MTs and AMELX in normal mandibular first molar tooth germs increased gradually after birth, peaked at 3 or 4 day postnatal, and then decreased. Expression of MTs and AMELX by immunocytochemistry was significantly delayed in neonatal mice raised in all-dark or all-light environment as well as the enamel development. Furthermore, development of tooth enamel was also delayed showing significant immature histology in those animals, especially for newborn mice raised in all daylight condition. Interestingly, disruption in circadian rhythm in pregnant mice also resulted in delayed enamel development in their babies. Treatment with melatonin receptor antagonist 4P-PDOT in pregnant mice caused underexpression of MTs and AMELX associated with long-lasting deficiency in baby enamel tissue. Electromicroscopic evidence demonstrated increased necrosis and poor enamel mineralization in ameloblasts. The above results suggest that circadian rhythm is important for normal enamel development at both pre- and postnatal stages. Melatonin receptors were partly responsible for the regulation. PMID:27494172

  6. In vitro demineralization of tooth enamel subjected to two whitening regimens.

    Science.gov (United States)

    Ogura, Kayoko; Tanaka, Reina; Shibata, Yo; Miyazaki, Takashi; Hisamitsu, Hisashi

    2013-07-01

    The resistance of bleached enamel to demineralization has not been elucidated fully. In this study, the authors aimed to examine the level of in vitro demineralization of human tooth enamel after bleaching by using two common bleaching regimens: home bleaching (HB) and office bleaching (OB) with photoirradiation. The authors bleached teeth to equivalent levels by means of the two bleaching regimens. They used fluorescence spectroscopy to measure the reduction in enamel density and the release of calcium into solution after storing the treated teeth in a demineralizing solution for two weeks. They also visualized and quantified mineral distribution in demineralized bleached enamel over time by using a desktop microcomputed-tomographic analyzer. Enamel subjected to HB or to photoirradiation without bleaching showed increased demineralization. In contrast, enamel treated with OB was more resistant to demineralization. This resistance to demineralization in teeth treated with OB presumably is due to peroxide's permeating to deeper layers of enamel before being activated by photoirradiation, which enhances mineralization. The mineral distribution pattern of enamel after treatment plays a critical role in providing resistance to demineralization in whitened teeth. OB confers to enamel significant resistance to in vitro demineralization. Dentists should supervise the nightguard HB process.

  7. Application of micro-PIXE analysis to investigate trace elements in deciduous teeth enamel

    International Nuclear Information System (INIS)

    Igari, K.; Takahashi, A.; Ando, H.

    2010-01-01

    The early life environment has widespread consequences for later health and disease. To prevent the disease in later life, the assessment of fetal environment is very important. In Japan, birthweight has fallen rapidly during recent two decades. The reduction of birthweight represents reduced fetal nutrition. Deciduous tooth enamel contains pre- and postnatal enamel and its chemical composition reflects the status of metabolism of trace elements during formation period. Deciduous tooth enamel is considered to be a suitable indicator of trace elements exposure in utero. We applied micro-PIXE analysis to investigate the trace elemental content in deciduous tooth enamel. Two deciduous canines from one healthy Japanese boy were used for this study. The enamel section including pre- and postnatal enamel was prepared for micro-PIXE analysis. Five trace elements (Na, Mg, Cl, Zn, and Sr) were detected in the scanning area of tooth. The distribution profiles of 5 elements were obtained as X-ray maps. The distribution profiles of zinc and chlorine were specific, and showed higher concentration in surface enamel. No elements showed different profiles of X-ray maps between pre- and postnatal enamel in this sample. The results of this study suggested that micro-PIXE analysis would be able to estimate the trace elements in prenatal and postnatal enamel, respectively. (author)

  8. Maturation Stage Enamel Malformations in Amtn and Klk4 Null Mice

    Science.gov (United States)

    Nunez, Stephanie M.; Chun, Yong-Hee P.; Ganss, Bernhard; Hu, Yuanyuan; Richardson, Amelia S; Schmitz, James E.; Fajardo, Roberto; Yang, Jie; Hu, Jan C-C.; Simmer, James P.

    2015-01-01

    Amelotin (AMTN) and kallikrein-4 (KLK4) are secreted proteins specialized for enamel biomineralization. We characterized enamel from wild-type, Amtn−/−, Klk4−/−, Amtn+/−Klk4+/− and Amtn−/−Klk4−/− mice to gain insights into AMTN and KLK4 functions during amelogenesis. All of the null mice were healthy and fertile. The mandibular incisors in Amtn−/−, Klk4−/− and Amtn−/−Klk4−/− mice were chalky-white and chipped. No abnormalities except in enamel were observed, and no significant differences were detected in enamel thickness or volume, or in rod decussation. Micro-computed tomography (µCT) maximum intensity projections localized the onset of enamel maturation in wild-type incisors distal to the first molar, but mesial to this position in Amtn−/−, Klk4−/− and Amtn−/−Klk4−/− mice, demonstrating a delay in enamel maturation in Amtn−/− incisors. Micro-CT detected significantly reduced enamel mineral density (2.5 and 2.4 gHA/cm3) in the Klk4−/− and Amtn−/−Klk4−/− mice respectively, compared with wild-type enamel (3.1 gHA/cm3). Backscatter scanning electron microscopy showed that mineral density progressively diminished with enamel depth in the Klk4−/− and Amtn−/−Klk4−/− mice. Knoop hardness of Amtn−/− outer enamel was significantly reduced relative to the wild-type and was not as hard as the middle or inner enamel. Klk4−/− enamel hardness was significantly reduced at all levels, but the outer enamel was significantly harder than the inner and middle enamel. Thus the hardness patterns of the Amtn−/− and Klk4−/− mice were distinctly different, while the Amtn−/−Klk4−/− outer enamel was not as hard as in the Amtn−/− and Klk4−/− mice. We conclude that AMTN and KLK4 function independently, but are both necessary for proper enamel maturation. PMID:26620968

  9. SEM Evaluation of Surrounding Enamel after Finishing of Composite Restorations- Preliminary Results

    Science.gov (United States)

    Iovan, G.; Stoleriu, S.; Solomon, S.; Ghiorghe, A.; Sandu, A. V.; Andrian, S.

    2017-06-01

    The purpose of this study was to analyze the surface characteristics of the enamel adjacent to composite resin after finishing the restoration with different diamond and tungsten carbide burs. The topography of enamel was observed by using a scanning electron microscope. Finishing with extra-/ultra-fine carbide burs, and extra-fine diamond burs resulted in smooth surfaces. In few areas some superficial scratches with no clinical relevance were observed. Deep grooves were observed on the surface of enamel when fine diamond burs were used. Finishing of composite restorations with coarse burs should be avoided when there is a high risk of touching and scratching adjacent enamel during the procedure.

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

    Science.gov (United States)

    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

  11. Bmp2 deletion causes an amelogenesis imperfecta phenotype via regulating enamel gene expression.

    Science.gov (United States)

    Guo, Feng; Feng, Junsheng; Wang, Feng; Li, Wentong; Gao, Qingping; Chen, Zhuo; Shoff, Lisa; Donly, Kevin J; Gluhak-Heinrich, Jelica; Chun, Yong Hee Patricia; Harris, Stephen E; MacDougall, Mary; Chen, Shuo

    2015-08-01

    Although Bmp2 is essential for tooth formation, the role of Bmp2 during enamel formation remains unknown in vivo. In this study, the role of Bmp2 in regulation of enamel formation was investigated by the Bmp2 conditional knock out (Bmp2 cKO) mice. Teeth of Bmp2 cKO mice displayed severe and profound phenotypes with asymmetric and misshaped incisors as well as abrasion of incisors and molars. Scanning electron microscopy analysis showed that the enamel layer was hypoplastic and enamel lacked a typical prismatic pattern. Teeth from null mice were much more brittle as tested by shear and compressive moduli. Expression of enamel matrix protein genes, amelogenin, enamelin, and enamel-processing proteases, Mmp-20 and Klk4 was reduced in the Bmp2 cKO teeth as reflected in a reduced enamel formation. Exogenous Bmp2 up-regulated those gene expressions in mouse enamel organ epithelial cells. This result for the first time indicates Bmp2 signaling is essential for proper enamel development and mineralization in vivo. © 2015 Wiley Periodicals, Inc.

  12. Biofilm extracellular polysaccharides degradation during starvation and enamel demineralization.

    Directory of Open Access Journals (Sweden)

    Bárbara Emanoele Costa Oliveira

    Full Text Available This study was conducted to evaluate if extracellular polysaccharides (EPS are used by Streptococcus mutans (Sm biofilm during night starvation, contributing to enamel demineralization increasing occurred during daily sugar exposure. Sm biofilms were formed during 5 days on bovine enamel slabs of known surface hardness (SH. The biofilms were exposed to sucrose 10% or glucose + fructose 10.5% (carbohydrates that differ on EPS formation, 8x/day but were maintained in starvation during the night. Biofilm samples were harvested during two moments, on the end of the 4th day and in the morning of the 5th day, conditions of sugar abundance and starvation, respectively. The slabs were also collected to evaluate the percentage of surface hardness loss (%SHL. The biofilms were analyzed for EPS soluble and insoluble and intracellular polysaccharides (IPS, viable bacteria (CFU, biofilm architecture and biomass. pH, calcium and acid concentration were determined in the culture medium. The data were analyzed by two-way ANOVA followed by Tukey's test or Student's t-test. The effect of the factor carbohydrate treatment for polysaccharide analysis was significant (p 0.05. Larger amounts of soluble and insoluble EPS and IPS were formed in the sucrose group when compared to glucose + fructose group (p < 0.05, but they were not metabolized during starvation time (S-EPS, p = 0.93; I-EPS, p = 0.11; and IPS = 0.96. Greater enamel %SHL was also found for the sucrose group (p < 0.05 but the demineralization did not increase during starvation (p = 0.09. In conclusion, the findings suggest that EPS metabolization by S. mutans during night starvation do not contribute to increase enamel demineralization occurred during the daily abundance of sugar.

  13. Enamel apatite crystallinity significantly contributes to mammalian dental adaptations

    Czech Academy of Sciences Publication Activity Database

    Kallistová, Anna; Skála, Roman; Šlouf, Miroslav; Čejchan, Petr; Matulková, I.; Horáček, I.

    2018-01-01

    Roč. 8, APR 3 2018 (2018), č. článku 5544. ISSN 2045-2322 R&D Projects: GA MŠk(CZ) LO1507 Institutional support: RVO:67985831 ; RVO:61389013 Keywords : tooth enamel * mechanical -properties * electron-microscopy * diffraction * teeth * size * morphology * behavior * minipig * pattern Subject RIV: EA - Cell Biology; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Other biological topics; Polymer science (UMCH-V) Impact factor: 4.259, year: 2016

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

    Science.gov (United States)

    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.

  15. In vitro effect of energy drinks on human enamel surface

    Directory of Open Access Journals (Sweden)

    Marise Sano Suga MATUMOTO

    Full Text Available Abstract Introduction Energy drinks (ED possess low pH and citric acid in their composition, making them potentially erosive beverages that can contribute to the high dental erosion rates found currently in the general population and also in young people. Objective To evaluate the mean pH and titratable acidity of commercial ED and the influence of a brand of ED on the superficial microhardness of human enamel. Material and method Ten commercial ED were selected and the pH of two lots of each ED with and without gas was obtained. Acid titration was conducted with the addition of NaOH aliquots until the pH 7 was reached. Eighteen human enamel specimens were allocated in three groups (N=6, Red Bull (RB, Red Bull Light (RBL and distilled water (C, submitted to an acid challenge with the ED, six consecutive times, with 12 hours intervals, during three days. Knoop microhardness was measured before and after the acid challenge. Result All ED brands tested presented low pH levels ranging from 2.1 to 3.2. Regarding titratable acidity, it was found that the amount of base required promoting the neutralization of the solutions ranged from 1200μL to 3750μL. Samples of human enamel in the RB and RBL groups submitted to the acid challenge presented significantly decreased Knoop microhardness when compared with the group C. Conclusion All ED examined have potential to promote mineral loss due to the low pH and high titratable acidity. The ED analyzed promoted significant mineral losses on the dental enamel surface.

  16. Microstructural analysis of demineralized primary enamel after in vitro toothbrushing

    Directory of Open Access Journals (Sweden)

    Neves Aline de Almeida

    2002-01-01

    Full Text Available The aim of this study was to investigate, in vitro, the morphological characteristics of demineralized primary enamel subjected to brushing with a dentifrice with or without fluoride. In order to do so, 32 enamel blocks were divided in 4 different groups containing 8 blocks each. They were separately immersed in artificial saliva for 15 days. The experimental groups were: C - control; E - submitted to etching with 37% phosphoric acid gel (30 s; EB - submitted to etching and brushing 3 times a day with a non-fluoridated dentifrice; EBF = submitted to etching and brushing 3 times a day with a fluoridated dentifrice. The toothbrushing force was standardized at 0.2 kgf and 15 double strokes were performed on each block. After the experimental period, the samples were prepared and examined under SEM. The control group (C showed a smooth surface, presenting scratches caused by habitual toothbrushing. The etched samples (E exhibited different degrees of surface disintegration, but the pattern of acid etching was predominantly the type II dissolution. The brushed surfaces were smooth, with elevations which corresponded to the exposure of Tomes? process pits and depressions which corresponded to interrod enamel. Particles resembling calcium carbonate were found in the most protected parts of the grooves. No morphological differences were observed between brushing with fluoridated (EBF and non-fluoridated (EB dentifrice. The results suggest that the mechanical abrasion caused by brushing demineralized enamel with dentifrice smoothes the rough etched surface, and the presence of fluoride does not cause morphological modifications in this pattern.

  17. AFM analysis of bleaching effects on dental enamel microtopography

    International Nuclear Information System (INIS)

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

    2010-01-01

    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 x 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.

  18. AFM analysis of bleaching effects on dental enamel microtopography

    Energy Technology Data Exchange (ETDEWEB)

    Pedreira de Freitas, Ana Carolina, E-mail: anacarolfreitas@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Cardoso Espejo, Luciana, E-mail: luespejo@hotmail.com [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Brossi Botta, Sergio, E-mail: sbbotta@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Sa Teixeira, Fernanda de, E-mail: nandast@if.usp.br [Laboratorio de Filmes Finos, Instituto de Fisica da Universidade de Sao Paulo, Rua do Matao, Travessa R, 187 - Cidade Universitaria, CEP 05314-970, Sao Paulo (Brazil); Cerqueira, Luz Maria Aparecida A., E-mail: maacluz@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Garone-Netto, Narciso, E-mail: ngarone@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Bona Matos, Adriana, E-mail: bona@usp.br [Departamento de Dentistica, Faculdade de Odontologia da Universidade de Sao Paulo, Av. Prof. Lineu Prestes, 2227 - Cidade Universitaria, CEP 05508-000, Sao Paulo (Brazil); Barbosa da Silveira Salvadori, Maria Cecilia, E-mail: mcsalva@if.usp.br [Laboratorio de Filmes Finos, Instituto de Fisica da Universidade de Sao Paulo, Rua do Matao, Travessa R, 187 - Cidade Universitaria, CEP 05314-970, Sao Paulo (Brazil)

    2010-02-15

    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 {mu}m x 15 {mu}m 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.

  19. Interaction between the enamel matrix proteins amelogenin and ameloblastin

    International Nuclear Information System (INIS)

    Ravindranath, Hanumanth H.; Chen, Li-Sha; Zeichner-David, Margaret; Ishima, Rieko; Ravindranath, Rajeswari M.H.

    2004-01-01

    Enamel matrix consists of amelogenin and non-amelogenins. Though amelogenin is not involved in nucleation of minerals, the enamel mineralization is impaired when amelogenin or other matrix protein (ameloblastin/enamelin) genes are mutated. We hypothesize that amelogenin may promote enamel mineralization by interacting with the calcium-binding matrix proteins. Specific binding of amelogenin to N-acetylglucosamine (GlcNAc), GlcNAc-mimicking peptides (GMps), and their carrier proteins and the identification of amelogenin-trityrosyl-motif-peptide (ATMP) as a GlcNAc/GMp-binding domain in amelogenin favor the hypothesis. This study tested the interaction of amelogenin with ameloblastin, a carrier of GMp sequence at intermittent sites. Neither GlcNAc nor sialic acids were identified in the recombinant-ameloblastin. Amelogenin bound to recombinant-ameloblastin in both Western blots and in ELISA. More specifically, [ 3 H]ATMP bound to both recombinant and native ameloblastins. Dosimetry and Scatchard analyses showed the specific interaction between ATMP and ameloblastin, suggesting that amelogenin may interact with ameloblastin to form a heteromolecular assembly

  20. Colour Change of Enamel after Application of Averrhoa bilimbi

    Directory of Open Access Journals (Sweden)

    Cut Fauziah

    2013-07-01

    Full Text Available Normal 0 false false false MicrosoftInternetExplorer4 Teeth discoloration is mainly treated with dental bleaching. Use of chemical bleaching has side effects, so it is important to find an alternative natural dental bleaching agent. Averrhoa bilimbi contains peroxide and oxalate acid that possess tooth whitening properties. Objective: To determine the change in color of dental enamel after the application of Averrhoa bilimbi and 10% carbamide peroxide. Methods: Samples were 20 post-extracted of the two tested materials premolars (10 specimens each for Averrhoa bilimbi and carbamide peroxide application. After the application, the specimens were incubated at 37ºC for 2 hours, washed and soaked in aquadest before further incubated for another 14 days. The colour changed was observed by 5 independent observers using shade guide. Results: Quantitative and qualitative analyzes were performed. Qualitatively, A3 color has changed into C1, A2, D2, B2 and B1 in the Averrhoa bilimbi group. A more significant color change in the 10% carbamide peroxide group (p=0.005 compared to Averrhoa bilimbi group (p=0.005 were observed. The difference of resulted enamel colour change was statistically significant (p=0.002. Conclusion: Averrhoa bilimbi had a good prospect as dental bleaching agent since its application effectively resulted in a slight enamel colour change although its whitening properties was still lower than 10% carbamide peroxide.DOI: 10.14693/jdi.v19i3.134

  1. A simple model for enamel fracture from margin cracks.

    Science.gov (United States)

    Chai, Herzl; Lee, James J-W; Kwon, Jae-Young; Lucas, Peter W; Lawn, Brian R

    2009-06-01

    We present results of in situ fracture tests on extracted human molar teeth showing failure by margin cracking. The teeth are mounted into an epoxy base and loaded with a rod indenter capped with a Teflon insert, as representative of food modulus. In situ observations of cracks extending longitudinally upward from the cervical margins are recorded in real time with a video camera. The cracks appear above some threshold and grow steadily within the enamel coat toward the occlusal surface in a configuration reminiscent of channel-like cracks in brittle films. Substantially higher loading is required to delaminate the enamel from the dentin, attesting to the resilience of the tooth structure. A simplistic fracture mechanics analysis is applied to determine the critical load relation for traversal of the margin crack along the full length of the side wall. The capacity of any given tooth to resist failure by margin cracking is predicted to increase with greater enamel thickness and cuspal radius. Implications in relation to dentistry and evolutionary biology are briefly considered.

  2. Interaction between the enamel matrix proteins amelogenin and ameloblastin.

    Science.gov (United States)

    Ravindranath, Hanumanth H; Chen, Li-Sha; Zeichner-David, Margaret; Ishima, Rieko; Ravindranath, Rajeswari M H

    2004-10-22

    Enamel matrix consists of amelogenin and non-amelogenins. Though amelogenin is not involved in nucleation of minerals, the enamel mineralization is impaired when amelogenin or other matrix protein (ameloblastin/enamelin) genes are mutated. We hypothesize that amelogenin may promote enamel mineralization by interacting with the calcium-binding matrix proteins. Specific binding of amelogenin to N-acetylglucosamine (GlcNAc), GlcNAc-mimicking peptides (GMps), and their carrier proteins and the identification of amelogenin-trityrosyl-motif-peptide (ATMP) as a GlcNAc/GMp-binding domain in amelogenin favor the hypothesis. This study tested the interaction of amelogenin with ameloblastin, a carrier of GMp sequence at intermittent sites. Neither GlcNAc nor sialic acids were identified in the recombinant-ameloblastin. Amelogenin bound to recombinant-ameloblastin in both Western blots and in ELISA. More specifically, [(3)H]ATMP bound to both recombinant and native ameloblastins. Dosimetry and Scatchard analyses showed the specific interaction between ATMP and ameloblastin, suggesting that amelogenin may interact with ameloblastin to form a heteromolecular assembly.

  3. Diffuse cavitary lung lesions

    Energy Technology Data Exchange (ETDEWEB)

    Grunzke, Mindy; Garrington, Timothy [University of Colorado Denver, Department of Pediatrics, Aurora, CO (United States); The Children' s Hospital, Rick Wilson Center for Cancer and Blood Disorders, Aurora, CO (United States); Hayes, Kari [The Children' s Hospital, Pediatric Radiology, Aurora, CO (United States); Bourland, Wendy [Children' s Hospital at St. Francis, Warren Clinic, Inc., Tulsa, OK (United States)

    2010-02-15

    An 11-year-old girl presented with a 2-month history of progressively worsening cough, daily fevers, and weight loss. A chest radiograph revealed multiple cystic cavitary lung lesions. An extensive infectious work-up was negative. Chest CT verified multiple cavitary lung lesions bilaterally, and [F-18]2-fluoro-2-deoxy-D-glucose ({sup 18}F-FDG) positron emission tomography with CT (PET/CT) showed increased uptake in the lung lesions as well as regional lymph nodes. Subsequent biopsy of an involved lymph node confirmed classical Hodgkin lymphoma, nodular sclerosis type. This case represents an unusual presentation for a child with Hodgkin lymphoma and demonstrates a role for {sup 18}F-FDG PET/CT in evaluating a child with cavitary lung lesions. (orig.)

  4. Diffuse cavitary lung lesions

    International Nuclear Information System (INIS)

    Grunzke, Mindy; Garrington, Timothy; Hayes, Kari; Bourland, Wendy

    2010-01-01

    An 11-year-old girl presented with a 2-month history of progressively worsening cough, daily fevers, and weight loss. A chest radiograph revealed multiple cystic cavitary lung lesions. An extensive infectious work-up was negative. Chest CT verified multiple cavitary lung lesions bilaterally, and [F-18]2-fluoro-2-deoxy-D-glucose ( 18 F-FDG) positron emission tomography with CT (PET/CT) showed increased uptake in the lung lesions as well as regional lymph nodes. Subsequent biopsy of an involved lymph node confirmed classical Hodgkin lymphoma, nodular sclerosis type. This case represents an unusual presentation for a child with Hodgkin lymphoma and demonstrates a role for 18 F-FDG PET/CT in evaluating a child with cavitary lung lesions. (orig.)

  5. Uterine Vascular Lesions

    Science.gov (United States)

    Vijayakumar, Abhishek; Srinivas, Amruthashree; Chandrashekar, Babitha Moogali; Vijayakumar, Avinash

    2013-01-01

    Vascular lesions of the uterus are rare; most reported in the literature are arteriovenous malformations (AVMs). Uterine AVMs can be congenital or acquired. In recent years, there has been an increasing number of reports of acquired vascular lesions of the uterus following pregnancy, abortion, cesarean delivery, and curettage. It can be seen from these reports that there is confusion concerning the terminology of uterine vascular lesions. There is also a lack of diagnostic criteria and management guidelines, which has led to an increased number of unnecessary invasive procedures (eg, angiography, uterine artery embolization, hysterectomy for abnormal vaginal bleeding). This article familiarizes readers with various vascular lesions of the uterus and their management. PMID:24340126

  6. In vitro progression of artificial white spot lesions sealed with an infiltrant resin.

    Science.gov (United States)

    Gelani, R; Zandona, A F; Lippert, F; Kamocka, M M; Eckert, G

    2014-01-01

    This study assessed the ability of an infiltrant resin (Icon, DMG Chemisch-Pharmazeutische Fabrik GmbH, Hamburg, Germany) to prevent artificial lesion progression in vitro when used to impregnate white spot lesions and also assessed the effect of saliva contamination on resin infiltration. Enamel specimens (n=252) were prepared and covered with nail varnish, leaving a window of sound enamel. After demineralization (pH 5.0; four weeks), specimens were divided into six groups (n=42 per group): group 1, 2% fluoride gel (positive control); group 2, resin infiltrant; group 3, resin infiltrant + fluoride gel; group 4, no treatment (negative control); group 5, resin infiltrant application after saliva contamination; and group 6, resin infiltrant + fluoride gel after saliva contamination. Specimens from each group were cut perpendicular to the surface, and one-half of each specimen was exposed to a demineralizing solution for another four weeks. The other half was set aside as a record of initial lesion depth and was used later in the determination of lesion progression. Lesion progression and infiltrant penetration were measured using confocal laser scanning microscopy (CLSM) and transverse microradiography (TMR). For lesion depth, based on CLSM, groups 2 and 3 showed the least changes when submitted to demineralization challenge, followed by group 1, then groups 5 and 6, and finally group 4. There were no significant differences between groups 2 and 3 or groups 5 and 6 in their ability to inhibit further lesion progression (p<0.05). Based on TMR, groups 2 and 3 also showed the fewest changes when submitted to demineralization challenge, followed by group 5, then groups 1 and 6, and finally group 4. In terms of mineral loss as measured by TMR, all groups that contained fluoride (groups 1, 3, and 6) show less percentage change in mineral loss than the groups that did not contain fluoride (groups 2, 4, and 5). It can be concluded that infiltrant penetration into early

  7. Male breast lesions

    International Nuclear Information System (INIS)

    Matushita, J.P.K.; Andrade, L.G. de; Carregal, E.; Marimatsu, R.I.; Matushita, J.S.

    1989-01-01

    Roentgenographic examination of the male breast is an important aspect of the continued, intensive investigation of the radiologic morphology of the normal and diseased breast conducted in 17 cases examined at the Instituto Nacional do Cancer - RJ. It is purpose of this report to present the Roentgen appearance of various lesions of the male breast as they have been found in our practice and also to stress some of the difficulties in the differential diagnosis of these lesions. (author) [pt

  8. Benign fibroosseous lesions

    Directory of Open Access Journals (Sweden)

    Cansu Köseoğlu Seçgin

    2016-05-01

    Full Text Available Benign fibroosseous lesions represent a group of lesions that share the same basic evolutive mechanism and are characterized by replacement of normal bone with a fibrous connective tissue that gradually undergoes mineralization. These lesions are presented by a variety of diseases including developmental, reactive-dysplastic processes and neoplasms. Depending on the nature and amount of calcified tissue, they can be observed as radiolucent, mixed or radiopaque. Their radiographic features could be well-defined or indistinguishable from the surrounding bone tissue. They can be asymptomatic as in osseous dysplasias and can be detected incidentally on radiographs, or they can lead to expansion in the affected bone as in ossifying fibroma. All fibroosseous lesions seen in the jaws and face are variations of the same histological pattern. Therefore, detailed clinical and radiographic evaluation in differential diagnosis is important. In this review, fibroosseous benign lesions are classified as osseous dysplasia, fibrous dysplasia and fibroosseous tumors; and radiographic features and differential diagnosis of these lesions are reviewed taking into account this classification.

  9. Kekerasan mikro enamel gigi permanen muda setelah aplikasi bahan pemutih gigi dan pasta remineralisasi (Enamel micro hardness of young permanent tooth after bleaching and remineralization paste application

    Directory of Open Access Journals (Sweden)

    Budianto Liwang

    2014-12-01

    Full Text Available Background: Studies showed that bleaching agent had demineralization effect to enamel, and encourage use of remineralization paste after bleaching treatment especially in young permanent tooth which in post-eruptive enamel maturation. Purpose: The study ere aimed to determine the bleaching agent effect on enamel surface micro hardness, and to determine the effect of remineralization paste application on enamel surface micro hardness of young permanent tooth after bleaching treatment. Methods: Fourteen young permanent teeth were placed in a block of resin with a window on the buccal surface enamel. The initial enamel surface hardness was measured using Microvickers Hardness Tester. Then the application of hydrogen peroxide bleaching materials 30% was done three times for 15 minutes and followed by surface hardness of enamel measurement. Samples were divided into 2 groups; the first group was applied paste of Hydroxy apatite + NaF 1450ppm , and the second group was applied paste of CPP–ACP + NaF 900ppm. Each paste was applied for 30 minutes for 7 days, then the enamel surface hardness of samples were measured. Results: The enamel surface micro hardness decreased after bleaching from 333.09 ± 10.49 VHN to 299.15±5.70 VHN. Micro hardness after application of Hidroxy apatite + NaF 1450ppm was 316.61±5.87 VHN and after application of CPP-ACP + NaF 900ppm was 319.94±3.25 VHN, however the micro hardness still lower than initial micro hardness. Conclusion: Tooth bleaching agent caused a decrease of enamel surface micro hardness in young permanent tooth. The use of remineralization paste enabled to increase the enamel surface micro hardness young permanent tooth.Latar belakang: Penelitian-penelitian sebelumnya menunjukkan bahwa produk pemutih gigi memiliki efek demineralisasi enamel gigi, dan mendorong penggunaan pasta remineralisasi setelah pemutihan gigi terutama di gigi muda permanen yang enamelnya masih dalam proses maturasi pasca-erupsi. Tujuan

  10. The abrasive effect of commercial whitening toothpastes on eroded enamel.

    Science.gov (United States)

    Mosquim, Victor; Martines Souza, Beatriz; Foratori Junior, Gerson Aparecido; Wang, Linda; Magalhães, Ana Carolina

    2017-06-01

    To evaluate the in vitro abrasive effect of commercial whitening toothpastes on eroded bovine enamel samples in respect to erosive tooth wear. 72 bovine crowns were embedded, polished and subjected to the baseline profile analysis. The samples were then protected in 2/3 of the enamel surface and were randomly assigned to six groups (n= 12/group): G1: Oral-B 3D White, G2: Close-up Diamond Attraction Power White, G3: Sorriso Xtreme White 4D, G4: Colgate Luminous White, G5: Crest (conventional toothpaste), G6:erosion only (control). All samples were submitted to an erosive pH cycling (4 x 90 seconds in 0.1% citric acid, pH 2.5, per day) and abrasive challenges (2 x 15 seconds, per day) for 7 days. After the first and the last daily cycles, the samples were subjected to abrasive challenges, using a toothbrushing machine, soft toothbrushes and slurry of the tested toothpastes (1.5 N). Between the challenges, the samples were immersed in artificial saliva. The final profile was obtained and overlaid to the baseline profile for the calculation of the erosive tooth wear (μm). The data were subjected to Kruskal-Wallis/Dunn tests (Penamel wear (3.68±1.06 μm), similarly to G3 (3.17± 0.80 μm) and G4 (3.44± 1.29 μm). G3 and G4 performed similarly between them and compared with G5 (2.35± 1.44 μm). G2 (1.51± 0.95 μm) and G6 (0.85± 0.36 μm) showed the lowest enamel wear, which did not differ between them and from G5. Oral-B 3D White showed the highest abrasive potential while Close-up Diamond Attraction Power White showed the lowest abrasive potential on eroded enamel in vitro. This study showed that some commercial whitening toothpastes, especially those containing pyrophosphate associated with hydrated silica, enhanced enamel erosive wear.

  11. Detection of early carious lesions using contrast enhancement with coherent light scattering (speckle imaging)

    International Nuclear Information System (INIS)

    Deana, A M; Jesus, S H C; Koshoji, N H; Bussadori, S K; Oliveira, M T

    2013-01-01

    Currently, dental caries still represent one of the chronic diseases with the highest prevalence and present in most countries. The interaction between light and teeth (absorption, scattering and fluorescence) is intrinsically connected to the constitution of the dental tissue. Decay induced mineral loss introduces a shift in the optical properties of the affected tissue; therefore, study of these properties may produce novel techniques aimed at the early diagnosis of carious lesions. Based on the optical properties of the enamel, we demonstrate the application of first-order spatial statistics in laser speckle imaging, allowing the detection of carious lesions in their early stages. A highlight of this noninvasive, non-destructive, real time and cost effective approach is that it allows a dentist to detect a lesion even in the absence of biofilm or moisture. (paper)

  12. Corrosion resistance properties of enamels with high B2O3-P2O5 content to molten aluminum

    International Nuclear Information System (INIS)

    Zhou, M.; Li, K.; Shu, D.; Sun, B.D.; Wang, J.

    2003-01-01

    Anticorrosive properties of borophosphate and boron-free enamels to molten aluminum were investigated using SEM and electron probe. Carbonates of alkali metal and alkaline earth metal were added in an appropriate weight ratio to achieve desired melting temperature of the enamels. SEM examination on the solidified interface between the enamels and aluminum alloy show that the enamels can spread slightly on aluminum alloy. For anticorrosive sample of borophosphate enamel, phosphorus was not detected by electron probe at the side of aluminum alloy near the interface, but silicon was detected in the silica-free enamels side. For the sample of boron-free enamels, however, phosphorus was found at the side of aluminum alloy near the interface. It was revealed that the enamels with high B 2 O 3 -P 2 O 5 content have high corrosion resistance to molten aluminum

  13. Intravesicular Phosphatase PHOSPHO1 Function in Enamel Mineralization and Prism Formation

    Directory of Open Access Journals (Sweden)

    Mirali Pandya

    2017-10-01

    Full Text Available The transport of mineral ions from the enamel organ-associated blood vessels to the developing enamel crystals involves complex cargo packaging and carriage mechanisms across several cell layers, including the ameloblast layer and the stratum intermedium. Previous studies have established PHOSPHO1 as a matrix vesicle membrane-associated phosphatase that interacts with matrix vesicles molecules phosphoethanolamine and phosphocholine to initiate apatite crystal formation inside of matrix vesicles in bone. In the present study, we sought to determine the function of Phospho1 during amelogenesis. PHOSPHO1 protein localization during amelogenesis was verified using immunohistochemistry, with positive signals in the enamel layer, ameloblast Tomes' processes, and in the walls of ameloblast secretory vesicles. These ameloblast secretory vesicle walls were also labeled for amelogenin and the exosomal protein marker HSP70 using immunohistochemistry. Furthermore, PHOSPHO1 presence in the enamel organ was confirmed by Western blot. Phospho1−/− mice lacked sharp incisal tips, featured a s