RESUMO
Human provenance studies employing isotopic analysis have become an essential tool in forensic and archaeological sciences, with multi-isotope approaches providing more specific location estimates compared to single isotope studies. This study reports on the human provenancing capability of neodymium isotopes (143Nd/144Nd), a relatively conservative tracer in the environment. Neodymium isotope ratios have only recently been determined on human remains due to low concentrations in human dental enamel (ppb range), requiring thermal ionisation mass spectrometry (TIMS) using 1013â¯Ω resistors. Dental elements (third molars) from 20 individuals born and raised in the Netherlands were analysed for Nd concentration (nâ¯=â¯12) and Nd isotope ratios (nâ¯=â¯15). The geological control on Nd isotope composition was examined using coupled Nd-Sr isotope analysis of the same third molar. Teeth from different geological environments were also analysed (Caribbean, Columbian, and Icelandic, nâ¯=â¯5). Neodymium elemental concentrations in dental elements ranged between 0.1 and 7.9â¯ppb (median 0.5â¯ppb). The Dutch 143Nd/144Nd ratios of the provinces of Limburg and Friesland were between 0.5118 and 0.5121, with Dutch 87Sr/86Sr ratios in agreement with the previously established local range (0.708-0.710). The current findings were compared to previously published results on Nd concentration and composition from Dutch individuals. The concentration of Nd and 143Nd/144Nd ratios were weakly correlated (R2â¯=â¯0.47, nâ¯=â¯17) in Dutch human dental enamel. The majority (nâ¯=â¯25, 83.3%) of individuals had Nd and Sr isotope values isotopically indistinguishable from the geological environment in which their third molars formed and mineralised. However, the Nd isotope ratios of the Icelandic individual and several Dutch individuals (nâ¯=â¯4) suggested that Nd in enamel is not solely influenced by geological environment. In order for neodymium isotopes to be quantitatively applied in forensic and archaeological settings further analyses of individuals from various geographical regions with well-defined dietary Nd isotope data are required.
Assuntos
Esmalte Dentário/química , Isótopos/análise , Espectrometria de Massas , Dente Serotino/química , Neodímio/análise , Radioisótopos/análise , Adolescente , Região do Caribe , Criança , Colômbia , Dieta , Impedância Elétrica , Odontologia Legal/métodos , Humanos , Islândia , Países Baixos , Dinâmica Populacional , Isótopos de Estrôncio/análiseRESUMO
The aim was to evaluate the influence of different dentin preparation mode in the smear layer characteristics (SL), hybrid layer (HL), and microtensile bond strength (µTBS) to dentin with two resin cements. The occlusal dentin of 120 third molars was exposed. The teeth were divided into 4 groups (n=30) according to the dentin preparation mode: 1- fine grain diamond bur; 2- coarse grain diamond bur; 3- multi laminate carbide steel bur; and, 4- ultrasonic CV Dentus diamond bur. Each treated dentin group was divided into 2 sub-groups (n=15) according to the resin cement: (1) RelyX U200 and (2) RelyX ARC. Resin composite blocks were cemented on dentin. After storage at 37o C for 24 h, beams with a cross section area of 1.0 mm2 were obtained, and tested in a universal testing machine at a crosshead speed of 0.5 mm/min. Two additional teeth for each sub-group were prepared to analyze the SL and HL on a scanning electron microscopy. According to Kruskal-Wallis test and Dunn tests, there was no significant difference in µTBS among the rotary instruments within each resin cement group. RelyX ARC obtained higher µTBS values compared to RelyX U200 (p<0.05). RelyX ARC formed evident HL, which was not observed for RelyX U200. The dentin mode preparation did not influence the µTBS of the resin cements. The SL was different for all instruments. The cementing agent is more determinant in the hybrid layer formation and bond strength to dentin than the instruments applied on dentin.
Assuntos
Colagem Dentária , Preparo da Cavidade Dentária/métodos , Adesivos Dentinários/química , Dentina/química , Cimentos de Resina/química , Resistência à Tração , Bis-Fenol A-Glicidil Metacrilato , Análise do Estresse Dentário , Humanos , Microscopia Eletrônica de Varredura , Dente Serotino/química , Polietilenoglicóis , Ácidos Polimetacrílicos , Camada de EsfregaçoRESUMO
Abstract The aim was to evaluate the influence of different dentin preparation mode in the smear layer characteristics (SL), hybrid layer (HL), and microtensile bond strength (µTBS) to dentin with two resin cements. The occlusal dentin of 120 third molars was exposed. The teeth were divided into 4 groups (n=30) according to the dentin preparation mode: 1- fine grain diamond bur; 2- coarse grain diamond bur; 3- multi laminate carbide steel bur; and, 4- ultrasonic CV Dentus diamond bur. Each treated dentin group was divided into 2 sub-groups (n=15) according to the resin cement: (1) RelyX U200 and (2) RelyX ARC. Resin composite blocks were cemented on dentin. After storage at 37o C for 24 h, beams with a cross section area of 1.0 mm2 were obtained, and tested in a universal testing machine at a crosshead speed of 0.5 mm/min. Two additional teeth for each sub-group were prepared to analyze the SL and HL on a scanning electron microscopy. According to Kruskal-Wallis test and Dunn tests, there was no significant difference in µTBS among the rotary instruments within each resin cement group. RelyX ARC obtained higher µTBS values compared to RelyX U200 (p<0.05). RelyX ARC formed evident HL, which was not observed for RelyX U200. The dentin mode preparation did not influence the µTBS of the resin cements. The SL was different for all instruments. The cementing agent is more determinant in the hybrid layer formation and bond strength to dentin than the instruments applied on dentin.
Resumo O objetivo deste estudo foi avaliar a influência de diferentes modos de preparação da dentina nas características da smear layer (SL), da camada híbrida (CH) e na resistência de união à microtração (RUµT) à dentina com dois cimentos resinosos. A dentina oclusal de 120 terceiros molares humanos foi exposta. Os dentes foram divididos em 4 grupos (n=30) de acordo com o modo de preparação da dentina: 1 - ponta diamantada de granulação fina; 2 - ponta diamantada de granulação grossa; 3 - ponta de carboneto de aço multilaminada; 4 - ponta diamantada ultrassônica. Cada grupo foi subdividido em dois subgrupos (n=15) de acordo com o cimento resinoso: (1) RelyX U200 e (2) RelyX ARC. Blocos de resina composta foram cimentados na dentina. Após armazenamento a 37 °C por 24 h, as amostras foram cortadas para obter palitos com área de 1,0 mm2, os quais foram testados em máquina de ensaio universal com velocidade de 0,5 mm/min. Dois dentes adicionais por subgrupo foram preparados para analisar as características da SL e da CH em microscópio eletrônico de varredura. De acordo com o teste de Kruskal-Wallis e o teste de Dunn, não houve diferença significativa na RUµT entre os instrumentos rotatórios para cada cimento resinoso. RelyX ARC obteve maiores valores de RUµT em comparação ao RelyX U200 (p<0,05). RelyX ARC formou uma CH evidente, o que não foi observado para o RelyX U200. O modo de preparação da dentina não influenciou na RUµT dos cimentos resinosos. A SL foi diferente para todos os instrumentos. O agente de cimentação foi mais determinante na formação da camada híbrida e na resistência de união do que os instrumentos utilizados para preparar a dentina.
Assuntos
Humanos , Resistência à Tração , Colagem Dentária , Adesivos Dentinários/química , Cimentos de Resina/química , Preparo da Cavidade Dentária/métodos , Dentina/química , Polietilenoglicóis , Ácidos Polimetacrílicos , Microscopia Eletrônica de Varredura , Camada de Esfregaço , Bis-Fenol A-Glicidil Metacrilato , Análise do Estresse Dentário , Dente Serotino/químicaRESUMO
BACKGROUND AND AIM: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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).
Assuntos
Esmalte Dentário/química , Esmalte Dentário/ultraestrutura , Humanos , Microscopia de Polarização , Minerais/análise , Dente Serotino/químicaRESUMO
This study evaluates the bond strength of dentin prepared with Er:YAG laser or bur, after rewetting with chlorhexidine on long-term artificial saliva storage and thermocycling. One hundred and twenty human third molars were sectioned in order to expose the dentin surface (n = 10). The specimens were randomly divided in 12 groups according to treatment and aging: Er:YAG laser rewetting with deionized water (LW) and 24 h storage in artificial saliva (WC); LW and 6 months of artificial saliva storage + 12.000 thermocycling (6M), LW and 12 months of artificial saliva storage + 24.000 thermocycling (12M), Er:YAG laser rewetting with 2% chlorhexidine (LC) and WC, LC and 6M, LC and 12M, bur on high-speed turbine rewetting with deionized water (TW) and WC, TW6M, TW12M, bur on high-speed turbine + 2% chlorhexidine (TC) and WC, TC and 6M, TC and 12M. The specimens were etched with 35% phosphoric acid, washed, and dried with air. Single Bond 2 adhesive was applied and the samples were restored with a composite. Each tooth was sectioned in order to obtain 4 sticks, which were submitted to microtensile bond strength test (µTBS). The two-way ANOVA, showed no significant differences for the interaction between the factors and for the aging factor. Tukey 5% showed that the LC group had the lowest µTBS. The rewetting with chlorhexidine negatively influenced the bond strength of the preparation with the Er:YAG laser. The artificial saliva aging and thermocycling did not interfere with dentin bond strength.
Assuntos
Antibacterianos/farmacologia , Clorexidina/farmacologia , Colagem Dentária , Adesivos Dentinários/farmacologia , Dentina/efeitos dos fármacos , Dentina/efeitos da radiação , Análise do Estresse Dentário , Dentina/química , Humanos , Terapia a Laser , Dente Serotino/química , Dente Serotino/efeitos dos fármacos , Dente Serotino/efeitos da radiação , Resistência à Tração , Fatores de TempoRESUMO
The aim of this study was to evaluate the concentrations of calcium (Ca), inorganic phosphate (Pi) and fluoride (F) in carious dentin and in different layers of sound dentin. The samples examined were 52 permanent teeth (26 sound and 26 carious), which were subjected to two experiments to assess the mineral content of: 1) two layers (internal and external) of sound dentin and 2) sound and carious dentin. Ca and Pi were analyzed using a colorimetric method with arsenazo III (C22H18As2N4O14S2) and molybdate reagents, and F was analyzed using a specific electrode. A non-parametric test, the Mann-Whitney test, was used to verify differences between groups. Sound dentin showed a higher concentration of fluoride in the internal layer than in the external layer (P = 0.03), but no inter-layer differences in Ca or Pi concentration were evident. Lower concentrations of Ca, Pi and F were observed in carious dentin than in sound dentin (P < 0.05). The results of this study suggest that the internal layer of sound dentin has a higher fluoride content than the external layer, and that carious dentin has lower concentrations of Ca, Pi and F than sound dentin.
Assuntos
Cárie Dentária/patologia , Dentina/química , Arsenazo III , Cálcio/análise , Colorimetria/métodos , Corantes , Fluoretos/análise , Humanos , Indicadores e Reagentes , Eletrodos Seletivos de Íons , Dente Molar/química , Dente Serotino/química , Molibdênio , Fosfatos/análiseRESUMO
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.
Assuntos
Esmalte Dentário/química , Esmalte Dentário/ultraestrutura , Modelos Biológicos , Modelos Químicos , Dente Serotino/química , Adolescente , Simulação por Computador , Feminino , Dureza , Humanos , Masculino , Teste de Materiais , Estresse Mecânico , Propriedades de Superfície , Adulto JovemRESUMO
We present a new method to determine Sr/Ca changes in hard dental tissues based on laser ablation and spectroscopic detection. By using femtosecond Laser Induced Breakdown Spectroscopy (fs-LIBS), we micro mapped the relative amount of strontium in the enamel of three human lower third molar. We also analyzed the Sr/Ca ratio along the striae of Retzius. Results show that microlibs allows detection of variation in relative Sr/Ca ratio through enamel. The same values of Sr/Ca ratio were found along a single stria. The method has a precision better than 95% and is sensitive enough to detect Sr/Ca ratio variations among striae and within stria. Fs-LIBS generates information in a fast and simple way that can be used by non-specialists to make inferences about diet or mobility in human populations and fossil hominids.
Assuntos
Esmalte Dentário/química , Análise Espectral/métodos , Estrôncio/análise , Fatores Etários , Antropologia Física , Cálcio/análise , Fósseis , Humanos , Dente Serotino/anatomia & histologia , Dente Serotino/química , Dente Serotino/crescimento & desenvolvimento , Sensibilidade e EspecificidadeRESUMO
STATEMENT OF THE PROBLEM: The effectiveness of bond strength using dual-polymerizing cementing systems ([DCSs] defined as the combination of dual-polymerizing bonding agents and resin cements) used with indirect restorations has not been evaluated when used solely with the autopolymerizing mode. PURPOSE: This study evaluated the in vitro microtensile bond strength (MTBS) of fourth- and fifth-generation DCSs with indirect composite restorations either light polymerized or autopolymerized. MATERIAL AND METHODS: Occlusal dentin surfaces of 48 human third molars were exposed and flattened. Teeth were assigned to 8 groups (n=6) according to the DCS and polymerizing modes: All-Bond2/Duolink (AB2), Optibond/Nexus2 (OPT), Bond1/Lute-it (B1), and Optibond Solo Dual Cure/Nexus2 (SOLO). Bonding agents were applied to dentin surfaces and left in the unpolymerized state. Resin cements were applied to prepolymerized resin discs (2 mm thick/Z250), which were subsequently bonded to the dentin surfaces. The restored teeth were light polymerized according to manufacturers' instructions (PP/XL 3000) or allowed to autopolymerize (AP). Restored teeth were stored in water at 37 degrees C for 24 hours and were both mesio-distally and bucco-lingually sectioned to obtain multiple bonded beams (1.2 mm2 of cross-sectional area). Each specimen was tested in tension at a crosshead speed of 0.6 mm/min until failure. Data (MPa) were analyzed by 2-way analysis of variance and the Tukey post hoc test (alpha=.05). Failure patterns of tested specimens were analyzed using scanning electron microscopy. RESULTS: The mean (SD) MTBS values (MPa) were: AB2/PP: 36.9 (6.5); AB2/AP: 32.7 (7.3); B1/PP: 38.2 (7.0); B1/AP: 13.0 (4.2); SOLO/PP: 33.2 (7.2); SOLO/AP: 23.4 (3.4); OPT/PP: 30.8 (7.5); OPT/AP: 13.1 (5.8). The AP groups showed significantly lower MTBS than the PP groups (P<.0001), except for AB2, which showed no difference between polymerization modes (P=.2608). CONCLUSION: The autopolymerizing mode of some dual-polymerizing cement systems may not be effective in promoting bond strength.
Assuntos
Colagem Dentária/métodos , Falha de Restauração Dentária , Adesivos Dentinários/química , Dente Serotino/química , Análise de Variância , Análise do Estresse Dentário/métodos , Humanos , Luz , Resistência à TraçãoRESUMO
Despite fluoride (F) use in caries prevention, not much is known about its effects on tooth quality. This study evaluated the effect of tooth F concentration ([F]) on selected dentin structural and mechanical properties. Third molars (n = 136) from Toronto, which has 1 part per million (p.p.m.) water [F], Montreal (0.2 p.p.m. water [F]), and Fortaleza (Brazil) (0.7 p.p.m. water [F]), were analyzed for [F], dental fluorosis (DF) severity, ultrasound velocity, and dentin tubule size and density. The enamel [F] was found to vary between 32 and 940 p.p.m., the dentin [F] was found to vary between 110 and 860 p.p.m., while the DF severity varied between TF0 and TF4. The enamel [F] showed no correlation with dentin [F], DF severity, ultrasound velocity, dentin tubule size or density. The dentin [F] correlated with DF severity, dentin tubule size, and ultrasound velocity. DF severity showed a correlation with dentin [F] and ultrasound velocity. It was concluded that dentin [F] is an indicator of dentin structural properties (dentin tubule size and ultrasound velocity), while DF severity is an indicator of dentin mechanical properties (ultrasound velocity).
Assuntos
Dentina/efeitos dos fármacos , Dentina/diagnóstico por imagem , Fluoretos/farmacologia , Análise de Variância , Brasil , Esmalte Dentário/química , Esmalte Dentário/diagnóstico por imagem , Dentina/química , Dentina/ultraestrutura , Elasticidade , Fluoretação , Fluoretos/análise , Fluorose Dentária/diagnóstico por imagem , Fluorose Dentária/patologia , Humanos , Dente Serotino/química , Dente Serotino/diagnóstico por imagem , Dente Serotino/ultraestrutura , Análise de Ativação de Nêutrons , Ontário , Quebeque , Ultrassonografia , VibraçãoRESUMO
This study evaluated the effects of peroxide bleaching regimens on the ultimate tensile strength (UTS) of human enamel. A resin composite block was built-up on the bonded occlusal surface of 14 extracted, sound, erupted third molars to enable posterior preparation for the microtensile test. The bonded teeth were serially sectioned in a buccal-lingual direction into approximately 0.7-mm thick slices. Each slice was trimmed with a fine diamond bur to reduce the area of the buccal, internal slope of the cusps to a dumb-bell shape with a cross-sectional area of less than 1 mm2. The samples were randomly divided into seven groups (n = 10): unbleached control group and bleached groups treated with six bleaching regimens. The specimens were tested in tension at 0.5 mm/minute and the data were analyzed by ANOVA and Tukey test. Specimens from the control group presented 51.3 +/- 8.6 MPa, while the UTS of bleached enamel ranged from 22.0 +/- 5.6 to 36.3 +/- 9.1 MPa. All bleaching procedures significantly reduced enamel UTS (p < 0.05). Differences were also observed among treatments. The results suggested that bleaching regimens can significantly reduce enamel UTS.
Assuntos
Esmalte Dentário/efeitos dos fármacos , Peróxido de Hidrogênio/farmacologia , Peróxidos/farmacologia , Clareamento Dental , Ureia/análogos & derivados , Análise de Variância , Peróxido de Carbamida , Esmalte Dentário/química , Combinação de Medicamentos , Humanos , Dente Serotino/química , Dente Serotino/efeitos dos fármacos , Resistência à Tração/efeitos dos fármacos , Ureia/farmacologiaRESUMO
PURPOSE: To evaluate the long-term effects of etching time, adhesive system and storage condition on resin bond strength to dentin. METHODS: Twenty-five extracted human third molars had a flat dentin surface exposed. Two total-etch adhesives, Single Bond (SB) and One-Step (OS), and one self-etching adhesive system, Clearfil Liner Bond 2V (CL), were used. The adhesives were bonded to dentin according to their respective manufacturer's instructions. Additional groups of SB and OS systems were created, in which the phosphoric acid etching time was doubled (30 seconds). After bonding, build-up crowns were constructed incrementally with Z250 resin composite and the teeth were stored for 24 hours in distilled water at 37 degrees C. The teeth were serially and vertically sectioned to obtain several bonded beams with approximately 0.8 mm2 of cross-sectional area. Beams were tested in microtensile (0.6 mm/minute) either immediately (control) or after storage for 6 months or 1 year in either distilled water or mineral oil. Data were analyzed by ANOVA and Tukey's multiple comparison tests. RESULTS: Significant reductions (P< 0.05) in bond strength were observed after both long-term storage periods in water for all the materials, regardless of the etching time for SB and OS. Bond strengths were either preserved or increased in specimens stored in oil.
Assuntos
Falha de Restauração Dentária , Adesivos Dentinários/química , Dente Serotino/química , Água/efeitos adversos , Resinas Acrílicas/química , Análise de Variância , Resinas Compostas/química , Corrosão Dentária/métodos , Humanos , Poliuretanos/química , Fatores de TempoRESUMO
This study provided morphological evidence that discrepancies between the depth of demineralisation and the depth of resin infiltration can occur in some mild self-etch adhesives. Sound dentine specimens derived from extracted human third molars were bonded with 5 one-step and 5 two-step self-etch adhesives. One millimeter thick slabs containing the resin-dentine interfaces were immersed in 50 wt% aqueous ammoniacal silver nitrate and processed for TEM examination. A zone of partially etched but uninfiltrated dentine was identified beneath the hybrid layers in the milder versions of both one-step and two-step self-etch adhesives. This zone was characterised by the occurrence of silver deposits along the interfibrillar spaces of mineralised collagen fibrils. The silver infiltrated interfibrillar spaces were clearly identified from the one-step self-etch adhesives Xeno III, iBond, Brush&Bond and the experimental adhesive, and were thinner and only occasionally observed in the two-step self-etch adhesives Clearfil SE Bond and Clearfil Protect Bond. The more aggressive one-step and two-step adhesives that exhibit more abrupt transitions from completely demineralised to mineralised dentin were devoid of these silver-infiltrated interfibrillar spaces beneath the hybrid layers. Incomplete resin infiltration observed in some self-etch adhesives may be caused by the reduced etching potential of the acidic monomers toward the base of hybrid layers, or the presence of acidic but non-polymerisable hydrolytic adhesive components, creating potential sites for the degradation of the bonded created by these self-etch adhesives.
Assuntos
Cimentação/métodos , Corrosão Dentária/métodos , Adesivos Dentinários/química , Dentina/química , Dentina/ultraestrutura , Dente Serotino/química , Água/química , Condicionamento Ácido do Dente/métodos , Humanos , Técnicas In Vitro , Teste de Materiais , Aderências TeciduaisRESUMO
Enamel fluoride concentrations in buccal and lingual surfaces were determined in successive layers obtained by the acid etch method. The 48 unerupted third molar teeth were from subjects who had lived continuously since birth in two Brazilian towns (Barretos and Ribeirão Pr-eto) with different fluoride levels in the drinking water but with similar socioeconomic conditions. The DMFT index was determined for children 7-12 years old living in the two towns. Enamel fluoride concentrations were significantly higher in the teeth from the town with higher fluoride levels in drinking water. The children residing in the community with near-optimum fluoride concentration in the water had mean DMFT scores that were less than half those found in the community with a low level of fluoride in the drinking water.