Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.013
Filtrar
1.
Nature ; 583(7814): 66-71, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32612224

RESUMO

Dental enamel is a principal component of teeth1, and has evolved to bear large chewing forces, resist mechanical fatigue and withstand wear over decades2. Functional impairment and loss of dental enamel, caused by developmental defects or tooth decay (caries), affect health and quality of life, with associated costs to society3. Although the past decade has seen progress in our understanding of enamel formation (amelogenesis) and the functional properties of mature enamel, attempts to repair lesions in this material or to synthesize it in vitro have had limited success4-6. This is partly due to the highly hierarchical structure of enamel and additional complexities arising from chemical gradients7-9. Here we show, using atomic-scale quantitative imaging and correlative spectroscopies, that the nanoscale crystallites of hydroxylapatite (Ca5(PO4)3(OH)), which are the fundamental building blocks of enamel, comprise two nanometric layers enriched in magnesium flanking a core rich in sodium, fluoride and carbonate ions; this sandwich core is surrounded by a shell with lower concentration of substitutional defects. A mechanical model based on density functional theory calculations and X-ray diffraction data predicts that residual stresses arise because of the chemical gradients, in agreement with preferential dissolution of the crystallite core in acidic media. Furthermore, stresses may affect the mechanical resilience of enamel. The two additional layers of hierarchy suggest a possible new model for biological control over crystal growth during amelogenesis, and hint at implications for the preservation of biomarkers during tooth development.


Assuntos
Amelogênese , Esmalte Dentário/química , Ácidos/química , Cálcio/química , Carbonatos/química , Cristalização , Teoria da Densidade Funcional , Esmalte Dentário/ultraestrutura , Durapatita/química , Fluoretos/química , Humanos , Magnésio/química , Microscopia Eletrônica de Transmissão e Varredura , Sódio/química , Tomografia , Difração de Raios X
2.
J Appl Oral Sci ; 28: e20190163, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32236351

RESUMO

OBJECTIVE: This in vitro study evaluated the effect of commercial whitening dentifrices on erosive tooth wear (ETW) of bovine enamel samples, in comparison with commercial regular dentifrices. METHODOLOGY: Sixty bovine crowns were embedded in acrylic resin, polished and then had their baseline profile determined. They were randomly assigned to 5 groups (n=12/group), according to the type of commercial dentifrice to be tested: GI - Crest Anti-cavity Regular; GII - Crest 3D White; GIII - Colgate Total 12 Clean Mint; GIV - Colgate Optic White; GV - Placebo (negative control, fluoride-free dentifrice). The samples were submitted to daily erosive and abrasive challenges for 3 days. The erosive challenges were performed 3 times a day by immersing the specimens in 0.1% citric acid solution (pH 2.5) for 90 s. Each day after the first and last erosive challenges, the specimens were subjected to the abrasive challenge for 15 s, using a toothbrushing machine (Biopdi, São Carlos, SP, Brazil), soft toothbrushes and slurry (1:3 g/ml) of the tested toothpastes (1.5 N). The specimens were kept in artificial saliva between the challenges. The final profile was obtained and the ETW (µm) was calculated. Data were analyzed by Kruskal-Wallis and Dunn's tests (p<0.05). RESULTS: All dentifrices tested significantly reduced the enamel wear in comparison with the Placebo, except GIII. The median (95% CI) ETW was 1.35 (1.25-1.46)bc for GI, 1.17 (1.01-1.34)cd for GII, 1.36 (1.28-1.45)ab for GIII, 1.08 (1.04-1.14)d for GIV and 2.28 (2.18-2.39)a for GV. CONCLUSION: When dentifrices from the same manufacturer were compared, the whitening dentifrices led to similar or less wear than the regular ones.


Assuntos
Esmalte Dentário/efeitos dos fármacos , Clareadores Dentários/efeitos adversos , Erosão Dentária/induzido quimicamente , Cremes Dentais/efeitos adversos , Animais , Bovinos , Esmalte Dentário/química , Teste de Materiais , Estatísticas não Paramétricas , Propriedades de Superfície , Fatores de Tempo , Clareadores Dentários/química , Escovação Dentária/efeitos adversos , Cremes Dentais/química
3.
J Appl Oral Sci ; 28: e20190501, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32236356

RESUMO

INTRODUCTION: The acquired pellicle formation is the first step in dental biofilm formation. It distinguishes dental biofilms from other biofilm types. OBJECTIVE: To explore the influence of salivary pellicle formation before biofilm formation on enamel demineralization. METHODOLOGY: Saliva collection was approved by Indiana University IRB. Three donors provided wax-stimulated saliva as the microcosm bacterial inoculum source. Acquired pellicle was formed on bovine enamel samples. Two groups (0.5% and 1% sucrose-supplemented growth media) with three subgroups (surface conditioning using filtered/pasteurized saliva; filtered saliva; and deionized water (DIW)) were included (n=9/subgroup). Biofilm was then allowed to grow for 48 h using Brain Heart Infusion media supplemented with 5 g/l yeast extract, 1 mM CaCl2.2H2O, 5% vitamin K and hemin (v/v), and sucrose. Enamel samples were analyzed for Vickers surface microhardness change (VHNchange), and transverse microradiography measuring lesion depth (L) and mineral loss (∆Z). Data were analyzed using two-way ANOVA. RESULTS: The two-way interaction of sucrose concentration × surface conditioning was not significant for VHNchange (p=0.872), ∆Z (p=0.662) or L (p=0.436). Surface conditioning affected VHNchange (p=0.0079), while sucrose concentration impacted ∆Z (p<0.0001) and L (p<0.0001). Surface conditioning with filtered/pasteurized saliva resulted in the lowest VHNchange values for both sucrose concentrations. The differences between filtered/pasteurized subgroups and the two other surface conditionings were significant (filtered saliva p=0.006; DIW p=0.0075). Growing the biofilm in 1% sucrose resulted in lesions with higher ∆Z and L values when compared with 0.5% sucrose. The differences in ∆Z and L between sucrose concentration subgroups was significant, regardless of surface conditioning (both p<0.0001). CONCLUSION: Within the study limitations, surface conditioning using human saliva does not influence biofilm-mediated enamel caries lesion formation as measured by transverse microradiography, while differences were observed using surface microhardness, indicating a complex interaction between pellicle proteins and biofilm-mediated demineralization of the enamel surface.


Assuntos
Biofilmes/crescimento & desenvolvimento , Esmalte Dentário/microbiologia , Saliva/química , Sacarose/química , Desmineralização do Dente/microbiologia , Animais , Bovinos , Esmalte Dentário/química , Película Dentária/microbiologia , Dureza , Microrradiografia/métodos , Pasteurização , Valores de Referência , Saliva/microbiologia , Sacarose/análise , Propriedades de Superfície
4.
Nature ; 580(7802): 235-238, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32269345

RESUMO

The phylogenetic relationships between hominins of the Early Pleistocene epoch in Eurasia, such as Homo antecessor, and hominins that appear later in the fossil record during the Middle Pleistocene epoch, such as Homo sapiens, are highly debated1-5. For the oldest remains, the molecular study of these relationships is hindered by the degradation of ancient DNA. However, recent research has demonstrated that the analysis of ancient proteins can address this challenge6-8. Here we present the dental enamel proteomes of H. antecessor from Atapuerca (Spain)9,10 and Homo erectus from Dmanisi (Georgia)1, two key fossil assemblages that have a central role in models of Pleistocene hominin morphology, dispersal and divergence. We provide evidence that H. antecessor is a close sister lineage to subsequent Middle and Late Pleistocene hominins, including modern humans, Neanderthals and Denisovans. This placement implies that the modern-like face of H. antecessor-that is, similar to that of modern humans-may have a considerably deep ancestry in the genus Homo, and that the cranial morphology of Neanderthals represents a derived form. By recovering AMELY-specific peptide sequences, we also conclude that the H. antecessor molar fragment from Atapuerca that we analysed belonged to a male individual. Finally, these H. antecessor and H. erectus fossils preserve evidence of enamel proteome phosphorylation and proteolytic digestion that occurred in vivo during tooth formation. Our results provide important insights into the evolutionary relationships between H. antecessor and other hominin groups, and pave the way for future studies using enamel proteomes to investigate hominin biology across the existence of the genus Homo.


Assuntos
Esmalte Dentário/química , Esmalte Dentário/metabolismo , Fósseis , Hominidae , Proteoma/análise , Proteoma/metabolismo , Sequência de Aminoácidos , Animais , República da Geórgia , Humanos , Masculino , Dente Molar/química , Dente Molar/metabolismo , Homem de Neandertal , Fosfoproteínas/análise , Fosfoproteínas/química , Fosfoproteínas/metabolismo , Fosforilação , Filogenia , Proteoma/química , Espanha
5.
Arch Oral Biol ; 112: 104686, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32112967

RESUMO

OBJECTIVE: Aim of this in vitro study was to investigate erosive tooth loss in dependence of the enamel surface structure and presence of an acquired pellicle. METHODS: Enamel specimens from 19 bovine incisors (4 specimens/incisor) were allocated to four experimental groups (n = 19). The surfaces of half of the specimens were polished (two groups), while the other half was left native (two groups). Specimens of one polished and one native group were placed in pooled human saliva (30 min) for the formation of an acquired pellicle. Thereafter, all specimens were demineralized by superfusion with hydrochloric acid (17 min, pH 2.3) with collection of the superfluent. Erosive substance loss was determined by measuring the dissolved calcium content using a colorimetric assay with Arsenazo III reagent. Differences in erosive substance loss were statistically analyzed with respect to enamel surface and pellicle. A linear mixed effects model was fitted to the data and pairwise differences between groups were evaluated (significance level α= 0.05). RESULTS: Enamel surface structure (p < 0.001) and presence of pellicle (p = 0.01) had a significant effect on erosive substance loss. Polished surfaces with pellicle showed the lowest cumulative calcium release [nmol Ca/mm2] (means ± standard deviation: 48+/-5), followed by polished specimens without (51+/-9) and native specimens with pellicle (54+/-10). No significant differences were found between these groups. Highest cumulative calcium release was found for native specimens without pellicle (61+/-9; p < 0.05). CONCLUSIONS: Both enamel surface structure and the acquired pellicle are important determinants of the susceptibility to erosive tooth loss.


Assuntos
Esmalte Dentário/química , Película Dentária/química , Erosão Dentária , Animais , Bovinos , Ácido Cítrico , Solubilidade do Esmalte Dentário , Humanos , Ácido Clorídrico , Saliva
6.
Braz Oral Res ; 33: e121, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31939500

RESUMO

The objective of the study was to analyze the surface area (SA) of the wear caused by simulated chewing on human enamel and opposing restorative material, namely: composite resin (CR), porcelain fused to metal (PFM), lithium disilicate (LD), or monolithic zirconia (MZr). Forty-eight premolars were selected as enamel specimens and divided randomly into 4 groups (n = 48; n =12) used as antagonists in chewing simulation (250,000 loading cycles) against one of the four selected test materials. Enamel and material specimens were scanned and evaluated under digital microscope, and wear SA (mm2) were recorded. Descriptive statistics, paired t-test, one-way ANOVA, and post-hoc Tukey-HSD tests were used for statistics (p < 0.05). The smallest and largest SA were exhibited by enamel against LD (0.80 mm2) and PFM (1.74 mm2), respectively. PFM (3.48 mm2) showed the largest SA and CR (2.28 mm2) showed the smallest SA. Paired t-test for SA values showed significant difference (p < 0.05) in all wear comparisons between materials and enamel antagonists. The wear of materials were greater than that of their respective enamel antagonists (p < 0.05). One-way ANOVA of the logarithmic means of wear SA revealed significant differences (P<0.05). Post-hoc Tukey test revealed significance for PFM (p < 0.05) with other materials. Wear of all test materials was greater compared to the wear of enamel antagonists. PFM and LD caused the largest and the smallest enamel wear, respectively. CR, LD, and MZr are more resistant than PFM to wear after simulated chewing against enamel.


Assuntos
Resinas Compostas/química , Esmalte Dentário/química , Porcelana Dentária/química , Mastigação , Ligas Metalo-Cerâmicas/química , Desgaste dos Dentes/etiologia , Zircônio/química , Adolescente , Adulto , Análise de Variância , Polimento Dentário/métodos , Humanos , Processamento de Imagem Assistida por Computador , Teste de Materiais , Microscopia/instrumentação , Valores de Referência , Estatísticas não Paramétricas , Propriedades de Superfície , Adulto Jovem
7.
Arch Oral Biol ; 109: 104573, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31568993

RESUMO

OBJECTIVE: The purpose of this investigation was to establish microstructure, microhardness, fracture toughness, chemical composition, and crack repair of bovine enamel and to compare these features with their human counterparts. DESIGN: Bovine enamel fragments were prepared and optical microscopy and atomic force microscopy were used to establish microstructure; Raman spectroscopy was used to estimate composition and microindentation using Vickers testing was performed to evaluate hardness. RESULTS: A strong dependence between indentation load and microhardness values was observed, as was the case in human enamel. Similar microstructure and chemical composition between bovine and human enamel, 7.89% lower microhardness and 40% higher fracture toughness values for bovine enamel were found. CONCLUSION: From a structural and mechanical standpoint, bovine enamel is a suitable alternative to human enamel for in vitro testing of dental products.


Assuntos
Esmalte Dentário/química , Dureza , Animais , Bovinos , Microscopia de Força Atômica
8.
Mater Sci Eng C Mater Biol Appl ; 106: 110277, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31753341

RESUMO

The self-growth and self-strengthening of natural biomaterials provided us strategies for new materials design. In this paper, the microstructure and fracture mechanisms of the wild wolf tusk's enamel were studied. The enamel included four-order hierarchies, which were the hydroxyapatite (HAP) fiber (first-order, nano-scale, ploy-crystals), enamel rod (second-order, micro-scale, rope-like), enamel type (third-order, meso-scale, mat-like) and the enamel patterns (forth-order, macro-scale), respectively. It was interesting to find that the numerous nano-grains distributed disorderly in a single HAP fiber. The thousands HAP fibers bundled together to form the rope-like enamel rod. The protein ligaments were discovered between adjacent enamel rods. The out enamel, inner enamel and P&D-zones showed a criss-cross type and ran through whole enamel pattern in three-dimensional space. The enamel of the wild wolf tusk exhibited an excellent fracture toughness based on the nanoindentation tests. The fracture morphology in transverse direction indicated that the cracks preferred to propagate along the weak interface (protein or interrod) and cut those enamel rods perpendicular to the propagation direction. However, the cracks extended obviously forward along the step-like paths from the outmost surface of the enamel to the enamel-dentin junction in the longitudinal direction. It was considered that the protein ligament was the main reason for the good fracture toughness of the bulk enamel. Our studies reveal that the design strategies of the natural material can be applied to guide the development of high-performance artificial materials.


Assuntos
Esmalte Dentário/química , Animais , Análise do Estresse Dentário , Durapatita/química , Dureza , Microscopia Eletrônica de Varredura , Lobos
9.
Niger J Clin Pract ; 22(12): 1675-1679, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31793473

RESUMO

Aims: The aim of this in vitro investigation was to evaluate the efficiency of self-adhering flowable resin composite (Vertise Flow, Kerr, Orange, CA, USA) and different surface treatments in the repair microtensile bond strength (µTBS) of aged nanofill resin composites using a universal adhesive. Materials and Methods: Aged substrates (×5000 thermocycling) were prepared using a nanofill (Filtek Ultimate; 3M ESPE) resin composite and randomly assigned to different surface treatments: (1) no treatment (control), (2) acid etching with 37% phosphoric acid, (3) Al2O3sandblasting, and (4) sandblasting with CoJet (3M ESPE). After surface treatment, specimens were further divided into two groups: no universal adhesive application and universal adhesive application. Vertise Flow was added to the substrates at 2-mm layer increments to a height of 5 mm and light cured. Restored specimens were sectioned to obtain 1.0-mm2 beams for µTBS testing. Data were analyzed with two-way analysis of variance and Tukey's honest significant difference tests (P < 0.05). Results: The lowest µTBS values were recorded in the control and acid etching groups with no universal adhesive application (P < 0.05). Universal adhesive application significantly increased the repair µTBS values of all surface treatments (P < 0.05), except CoJet treatment. There were no significant differences between Al2O3sandblasting, CoJet application, and acid etching groups with the universal adhesive application (P > 0.05). Conclusion: Vertise Flow can be used effectively in the repair of old nanofill resin composites. The usage of universal adhesive with prior acid etching to obtain acceptable repair performance would be the practical choice under clinical conditions.


Assuntos
Resinas Compostas/química , Colagem Dentária/métodos , Esmalte Dentário/química , Adesivos Dentinários , Dentina/química , Cimentos de Resina/química , Adesivos , Análise do Estresse Dentário , Humanos , Teste de Materiais/métodos , Propriedades de Superfície , Resistência à Tração
10.
Cient. dent. (Ed. impr.) ; 16(3): 201-207, sept.-dic. 2019. tab, ilus
Artigo em Espanhol | IBECS | ID: ibc-185995

RESUMO

Introducción: El empleo de dientes autógenos, como material de injerto, es una opción terapéutica actual en casos de regeneración ósea. Su obtención se ha facilitado con la introducción de dispositivos capaces de procesar los dientes. El objetivo de este trabajo es realizar, a propósito de un caso clínico, una revisión de la literatura sobre el uso de dientes autólogos como material de injerto óseo y los dispositivos para su procesamiento. Caso clínico: Paciente varón de 18 años que acude a consulta presentando un cordal inferior retenido. El diagnóstico determinó la necesidad de extraer el diente y se informó al paciente de la posibilidad de utilizarlo como material de regeneración ósea. Tras la exodoncia, el diente procesado con el dispositivo Tooth Transformer(R) (Imbiodent), fue utilizado como material de injerto autólogo. El postoperatorio no presentó ninguna complicación y la evaluación radiográfica, tras 8 días y tras 10 semanas, mostró una evolución favorable del tratamiento. Discusión: La dentina desmineralizada es un material orgánico cuyo potencial reside en los factores de crecimiento que contiene para estimular la formación y reparación ósea. No obstante, no existe consenso sobre el grado de desmineralización o tamaño de partícula ideal. La reciente introducción de dispositivos, capaces de procesar dientes, facilita la obtención de un material de injerto dental para su uso en terapias de regeneración ósea. Conclusión: El uso de dientes autólogos constituye una alternativa prometedora en el campo de los injertos óseos. La técnica de transformación del diente es sencilla con el empleo de los dispositivos actuales


Introduction: The use of autogenous teeth, as graft material, is a current therapeutic option in cases of bone regeneration. Its obtention has been facilitated by the introduction of devices capable of processing teeth. The aim of this article is to perform, based on a clinical case, a review of the literature about the use of autologous teeth as bone graft material and the devices for its processing. Clinical case: Male patient, 18 years of age, who comes to the dental office presenting a lower wisdom retained. Extraction of the tooth was determined by diagnosis and the patient was informed about the possibility of using it as bone regeneration material. After the extraction, the tooth was processed by the Tooth Transformer(R) (Imbiodent) device and was used as autologous graft material. No postoperative complications were presented and the radiographic evaluation, at 8 days and 10 weeks, showed a favorable evolution of the treatment. Discusion: Demineralized dentin is a organic material whose potential relies in the growth factors it contains to stimulate bone formation and repair. However, there is no consensus on the degree of demineralization or the ideal particle size. The recent introduction of devices, capable of processing teeth, enables the obtention of a dental graft material for bone regeneration therapies. Conclusion: The use of autologous teeth is a promising alternative in the bonev grafts field. The technique of tooth transformation is simple with the use of the current devices


Assuntos
Humanos , Masculino , Adolescente , Regeneração Óssea , Polpa Dentária/citologia , Dentina , Carga Imediata em Implante Dentário/métodos , Transplante Ósseo/métodos , Procedimentos Cirúrgicos Reconstrutivos , Desmineralização do Dente , Esmalte Dentário/química , Procedimentos Cirúrgicos Bucais/métodos
11.
Braz Oral Res ; 33: e101, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31778472

RESUMO

The aim of this study was to evaluate the influence of different calcium phosphates (CaPs) on the physical, biological, and remineralizing properties of experimental resin-based sealants (RBSs). Triethylene-glycol dimethacrylate (90wt%) and bisphenol A-glycidyl methacrylate (10wt%) were used to produce resin-based sealants. Hydroxyapatite (SHAp), α-tricalcium phosphate (Sα-TCP) and octacalcium phosphate (SOCP) were added to the sealants in a 10wt% concentration. One group without CaPs was used as the control group (SCG). The degree of conversion (DC) was assessed with Fourier-transformed infrared spectroscopy, whereas cytotoxicity was tested with the HaCaT keratinocyte cell line. The ultimate tensile strength (UTS) was used to assess the mechanical strength of the experimental RBSs. Sealed enamel was used for colorimetric assay. Mineral deposition was assessed with Raman spectroscopy after 7, 14, and 28 days of sample immersion in artificial saliva. Scanning electron microscopy was used to analyze the surface morphology after 28 days of immersion. The addition of 10wt% of fillers significantly reduced the DC of sealants. SOCP groups showed reduced cell viability. Higher UTS was found for Sα-TCP and SHAp. The color analysis showed that SGC and demineralized teeth presented higher mismatches with the sound tissue. Mineral deposition was observed for SHAp and Sα-TCP after 7 days, with increased phosphate content and mineral deposits for SHAp after 28 days. RBS with the addition of 10% HAp promoted increased mineralization in vitro after 28 days, and did not affect cell viability, DC, mechanical properties, or RBS color in the enamel.


Assuntos
Fosfatos de Cálcio/química , Durapatita/química , Minerais/química , Selantes de Fossas e Fissuras/química , Resinas Sintéticas/química , Animais , Fosfatos de Cálcio/toxicidade , Bovinos , Linhagem Celular , Colorimetria , Esmalte Dentário/química , Esmalte Dentário/efeitos dos fármacos , Durapatita/toxicidade , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Selantes de Fossas e Fissuras/toxicidade , Valores de Referência , Reprodutibilidade dos Testes , Resinas Sintéticas/toxicidade , Saliva Artificial/química , Análise Espectral Raman , Propriedades de Superfície , Resistência à Tração , Fatores de Tempo
12.
Braz Oral Res ; 33: e120, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31778475

RESUMO

The objective of this study is to compare the resin-enamel bond strength (mµSBS), in-situ degree of conversion (DC), and the enamel-etching pattern (SEM/EDX) of universal adhesive systems when applied to sound and fluorotic enamel. Ninety-eight human molars were sectioned into 4 parts and divided into 24 groups according to 1) enamel surface (sound or fluorotic enamel), 2) adhesive system (Clearfil Universal Bond [CUB], Futurabond U [FBU], iBond Universal [IBU], and Scotchbond Universal [SBU]), and 3) application mode (etch-and-rinse [ER], active self-etch [Active-SE], and passive self-etch [Passive-SE]). Specimens were stored at 37 °C, for 24 hours and tested at 1.0 mm/min (µSBS). Enamel-resin interfaces were evaluated for in-situ DC. The enamel-etching pattern was evaluated under a SEM/EDX. Data from mµSBS and in-situ DC was analyzed using a three-way ANOVA and Tukey's test at 5 % level of significance. For all adhesives, the ER resulted in a statistically significant higher mean mµSBS than the passive-SE in both substrates (p < 0.001). For all adhesives, active-SE resulted in mean mµSBS (p > 0.31) and in-situ DC (p > 0.45) that were statistically similar to those obtained with the ERs in both substrates. A statistically significant, higher mean mµSBS and in-situ DC were obtained in sound enamel (p < 0.001) than in fluorotic enamel. In general, SBU showed higher mean values for mµSBS and in-situ DC compared to those of CUB and IBU (p < 0.001). ER and active-SE showed the deepest enamel-etching pattern in both substrates. A higher amount of fluor was observed in fluorotic enamel. The active application of universal adhesives in the SE-mode may be a viable alternative to increase the adhesive properties in sound and fluorotic enamel.


Assuntos
Colagem Dentária/métodos , Esmalte Dentário/química , Esmalte Dentário/efeitos dos fármacos , Fluorose Dentária , Cimentos de Resina/química , Análise de Variância , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Distribuição Aleatória , Valores de Referência , Reprodutibilidade dos Testes , Resistência ao Cisalhamento/efeitos dos fármacos , Espectrometria por Raios X , Análise Espectral Raman , Propriedades de Superfície/efeitos dos fármacos
13.
Braz Oral Res ; 33: e098, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31664361

RESUMO

The aim was to evaluate the effect of 2% grape seed extract (GSE) containing phosphoric acid (PhA) on the bond strength to enamel and dentin. The control group was 37% PhA. The following three PhA formulations with 2% GSE and 20% ethanol were obtained: GSE5 = 5% PhA; GSE10 = 10% PhA; and GSE20 = 20% PhA. The enamel and dentin surfaces of molars were etched with the acid solutions, followed by Scotchbond Multi-Purpose adhesive and composite resin application. The tensile bond strength (TBS) test evaluated the bond to enamel after 24 h, and the microtensile bond strength (µTBS) test evaluated the bond to dentin after 24 h and 12-month water storage. Etched enamel and dentin were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively. The TBS data were submitted to one-way ANOVA, while µTBS data were submitted to two-way ANOVA and Tukey's test (α = 0.05). The TBS (MPa) to enamel did not significantly differ among the control (48.1 ± 15.7), GSE5 (46.1 ± 9.6), GSE10 (49.8 ± 13.6) and GSE20 (44.1 ± 11.9) groups (p = 0.537). The µTBS (MPa) to dentin of the control (28.4 ± 14.4) and GSE20 (24.1 ± 8.1) groups were significantly higher than those of the GSE5 (16.8 ± 7.4) and GSE10 (17.5 ± 6.6) groups at 24 h (p < 0.006). After 12-month storage, only GSE5 (21.0 ± 7.8) and GSE10 (17.6 ± 8.0) did not show significantly decreased µTBS (p > 0.145). SEM micrographs showed a shallower enamel etching pattern for GSE5. AFM images showed the formation of collagenous globular structures for GSE5 and GSE10. The different acid solutions did not influence the TBS to enamel, and the µTBS to dentin was stable over time when dentin was etched with GSE5 and GSE10.


Assuntos
Condicionamento Ácido do Dente/métodos , Colagem Dentária/métodos , Esmalte Dentário/efeitos dos fármacos , Dentina/efeitos dos fármacos , Extrato de Sementes de Uva/química , Ácidos Fosfóricos/química , Adolescente , Adulto , Análise de Variância , Esmalte Dentário/química , Dentina/química , Humanos , Teste de Materiais , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Valores de Referência , Reprodutibilidade dos Testes , Estatísticas não Paramétricas , Propriedades de Superfície/efeitos dos fármacos , Resistência à Tração , Fatores de Tempo , Adulto Jovem
14.
Braz Oral Res ; 33: e0088, 2019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31531566

RESUMO

The main of the study was quantify the effect of two ceramics with two underlying resin cements on apparent fluorescence levels. Buccal surfaces of two bovine incisors were ground flat producing one enamel and one dentin substrate. The veneers were fabricated (0.5 and 1.0 mm thickness) using two ceramics (IPSe.max Press and IPSe.max Zirpress, Ivoclar Vivadent). Veneers were cemented using either light-cured (Variolink II, Ivoclar Vivadent) or self-adhesive dual (Rely X U200, 3M ESPE) cement. The layered Control group materials had no cement application. Semi-quantitative fluorescence image analysis (Matlabs software, Matworks) involved processing the images as captured under each daylight (DL, Gretagmacbeth) and ultraviolet illuminants (UVA, Sylvania) within a neutral-gray lightbox (Macbeth Spectral Light). Statistical analysis of the quantitative fluorescence values was performed using two-way ANOVA and Tukey's test (p < 0.05). The e.max Zirpress on the dentin substrate produced greater fluorescence (p < 0.05) when subjected to UV illumination and more fluorescence (p < 0.05) than e.max Press in both cement groups. Light-cured cement produced higher (p < 0.05) fluorescence than the dual-cement with e.max Press on enamel under UV illumination. The fluorescence for e.max Press on the dentin substrate was greater (p < 0.05) than for e.max Zirpress using dual self-adhesive cement subjected to daylight illumination. Thus, it is possible to conclude that the combination of ceramic and cement produce definite, significant effects on the apparent fluorescence, vital quality for restorative dentistry.


Assuntos
Cerâmica/química , Facetas Dentárias , Imagem Óptica/métodos , Cimentos de Resina/química , Animais , Bovinos , Esmalte Dentário/química , Esmalte Dentário/efeitos dos fármacos , Dentina/química , Dentina/efeitos dos fármacos , Luz , Teste de Materiais , Valores de Referência , Reprodutibilidade dos Testes , Propriedades de Superfície
15.
Sci Adv ; 5(8): eaaw9569, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31497647

RESUMO

The regeneration of tooth enamel, the hardest biological tissue, remains a considerable challenge because its complicated and well-aligned apatite structure has not been duplicated artificially. We herein reveal that a rationally designed material composed of calcium phosphate ion clusters can be used to produce a precursor layer to induce the epitaxial crystal growth of enamel apatite, which mimics the biomineralization crystalline-amorphous frontier of hard tissue development in nature. After repair, the damaged enamel can be recovered completely because its hierarchical structure and mechanical properties are identical to those of natural enamel. The suggested phase transformation-based epitaxial growth follows a promising strategy for enamel regeneration and, more generally, for biomimetic reproduction of materials with complicated structure.


Assuntos
Apatitas/química , Materiais Biomiméticos/química , Esmalte Dentário/química , Animais , Cristalização , Humanos
16.
J Appl Oral Sci ; 27: e20180593, 2019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31508792

RESUMO

There is growing evidence that C. albicans is associated with dental caries, but its role on caries development needs to be better clarified. Label="OBJECTIVE">To evaluate at the hard tissue level the effect of C. albicans on the cariogenic potential of S. mutans biofilms focusing on the mineral profile of induced carious lesions. This study also aimed to evaluate the effect of C. albicans on the acidogenic potential of S. mutans biofilms. METHODOLOGY Dual-species (CA+SM) and single-species biofilms (CA or SM) were grown on the surface of enamel slabs in the presence of glucose/sucrose supplemented culture medium for 24, 48 and 72 hours. Demineralization was evaluated through percentage of surface microhardness change (%SMC) and transversal microradiography analysis (ILM and LD) and pH of the spent medium was recorded daily. Data were analyzed by two-way ANOVA followed by Bonferroni correction. RESULTS%SMC was statistically different among the biofilms at each time point being the highest for SM biofilms and the lowest for CA biofilms which also differed from CA+SM biofilms [SM (24 h: 47.0±7.3; 48 h: 66.3±8.3; 72 h: 75.4±3.9); CA (24 h: 7.3±3.3; 48 h: 7.1±6.4; 72 h: 6.6±3.6); CA+SM (24 h: 35.9±7.39.1; 48 h: 47.2±9.5; 72 h: 47.6±9.5)]. pH of spent medium was statistically lower for SM biofilms compared to the other biofilms at each time point and remained constant over time while pH values increased from 24 to 72 h for both CA and CA+SM biofilms [SM (24 h: 4.4±0.1; 48 h: 4.4±0.1; 72 h: 4.5±0.1); CA (24 h: 6.9±0.3; 48 h: 7.2±0.2; 72 h: 7.5±0.2); CA+MS (24 h: 4.7±0.2; 48 h: 5.1±0.1; 72 h: 6.1±0.6)]. IML and LD for SM biofilms increased over time while no difference was observed from 24 to 72 h for the other biofilms. CONCLUSIONS The present data suggest that C. albicans has low enamel demineralization potential and the presence of C. albicans can reduce both the cariogenic and acidogenic potentials of S. mutans biofilms.


Assuntos
Biofilmes/crescimento & desenvolvimento , Candida albicans/fisiologia , Esmalte Dentário/microbiologia , Streptococcus mutans/metabolismo , Desmineralização do Dente/microbiologia , Ácidos/metabolismo , Animais , Bovinos , Contagem de Colônia Microbiana , Esmalte Dentário/química , Testes de Dureza , Concentração de Íons de Hidrogênio , Microrradiografia/métodos , Valores de Referência , Propriedades de Superfície , Fatores de Tempo
17.
Biomed Mater Eng ; 30(4): 365-374, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31476141

RESUMO

BACKGROUND: Ceramic crown that fires the layering porcelain on zirconia corping is starting to be used due to aesthetic requirements. However, many ceramics are used, but wear characteristics are often unknown. OBJECTIVE: This study was performed to investigate the wear of human enamel by porcelains, and to determine the influence of porcelain hardness, surface roughness and crystal of porcelain on the enamel wear. METHODS: Enamel specimens were prepared from extracted human molar teeth. Porcelain specimens were prepared from Deguceram Gold, Vita Omega 900, and Cercon Ceram Kiss. Enamel wear volume was calculated and the porcelain wear depth, surface roughness and Vickers hardness was measured. Moreover, the observation of a crystal by scanning electron microscope and the crystal by X-ray diffraction were identified. RESULTS: Omega 900 showed the smallest enamel wear volume and porcelain wear depth. The Vickers hardnesses of Omega 900 and Cercon Ceram Kiss were almost identical. Leucite was detected from Deguceram Gold and Omega 900, and Silica and Silicon Nitride were detected from Cercon Ceram Kiss. CONCLUSIONS: The enamel wear is influenced not by the hardness of the porcelain but by the surface roughness, the size and shape of the crystal.


Assuntos
Coroas , Esmalte Dentário/anatomia & histologia , Porcelana Dentária/química , Coroas/efeitos adversos , Cristalização , Esmalte Dentário/química , Porcelana Dentária/efeitos adversos , Desgaste de Restauração Dentária/efeitos adversos , Dureza , Humanos , Teste de Materiais , Propriedades de Superfície , Difração de Raios X
18.
Biomed Mater Eng ; 30(4): 439-448, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31476144

RESUMO

BACKGROUND: Adhesion strength of orthodontic attachments to enamel should be within optimal range to resist occlusal forces and to allow debonding without enamel damage. OBJECTIVE: The present study compared the effect of non-thermal plasma (NTP) and conventional surface treatment on the adhesion strength of orthodontic bracket to enamel. METHODS: A total of 100 premolar teeth were allocated into 5 groups according to the bonding procedure followed: Group 1 (Etch, prime and composite adhesive); Group 2 (Prime and composite adhesive); Group 3 (Glass ionomer cement); Group 4 (NTP, prime and composite adhesive) and Group 5 (NTP and glass ionomer cement). Ten specimens in each group were subjected to artificial aging and the remaining ten specimens served as baseline specimens. Adhesion strength values were recorded after debonding and bond failure types were scored. Water contact angles of the NTP treated and untreated enamel surface were measured. RESULTS: Group 1 specimen demonstrated highest bond strength at baseline (21.5 ± 3.01) and thermocycling (15.8 ± 2.87) and the least values were in Group 2 specimens at baseline (3.9 ± 1.01) and thermocycling (1.6 ± 0.7). Among the experimental (NTP) groups, Group 4 specimens exhibited high adhesion strength at baseline (10.2 ± 1.76) and after thermocycling (9.8 ± 2.15) compared to Group 5 specimens at baseline (10.1 ± 1.05) and thermocycling (6.5 ± 2.19). The water contact angle on untreated enamel surface was 53.1° ± 2.1° as compared to 1.4° ± 0.7° in treated surface. CONCLUSION: Non-thermal plasma (NTP) treatment in conjunction with composite adhesives demonstrated clinically acceptable adhesion strength and was well within the optimal range (7-14 MPa) for enamel bonding.


Assuntos
Adesivos/química , Esmalte Dentário/química , Braquetes Ortodônticos , Adesividade , Análise do Estresse Dentário , Retenção de Dentadura/efeitos adversos , Cimentos de Ionômeros de Vidro/química , Humanos , Teste de Materiais , Braquetes Ortodônticos/efeitos adversos , Gases em Plasma , Cimentos de Resina/química
19.
Forensic Sci Int ; 302: 109919, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31451316

RESUMO

We report isotopic ratios for δ18O and 87Sr/86Sr from 71 individual human permanent teeth, obtained from 61 individuals with known regions of origins from eight of the 32 departments in Colombia. This survey of the applicability of isotopic provenancing is a vital addition to the ongoing identification efforts within Colombia concerning unidentified decedents recovered from clandestine and cemetery burials. At this time, only median isotopic values are reported due to heterogeneity of inter- and intra-departmental variance among the obtained isotopic values. The use of department of origin as a regional assignment schema is inadequate to effectively georeference unidentified human remains, given the wide-ranging topography and climatic diversity within Colombia. Therefore, a critical need for additional isotopic sampling of individual reference material exists, in order to improve the accuracy of potential region of origin estimates of unknown decedents originating from forensic contexts within Colombia.


Assuntos
Esmalte Dentário/química , Durapatita/química , Odontologia Legal/métodos , Isótopos de Oxigênio/análise , Isótopos de Estrôncio/análise , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Conflitos Armados , Restos Mortais , Colômbia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
20.
Protein Pept Lett ; 26(12): 880-886, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31364509

RESUMO

Amelognein protein plays a vital role in the formation and mineralization of enamel matrix. Amelogenin structure is complex in nature and researchers have studied it with different experimental techniques. Considering its important role, there is a need to understand this important protein, which has been discussed in detail in this review. In addition, various experimental techniques to study amelogenin protein used previously have been tackled along with their advantages and disadvantages. A selection of 67 relevant articles/book chapters was included in this study. The review concluded that amelogenins act as nanospheres or spacers for the growth of enamel crystals. Various experimental techniques can be used to study amelogenins, however, their advantages and drawbacks should be kept in mind before performing analysis.


Assuntos
Amelogenina/química , Amelogenina/metabolismo , Esmalte Dentário/química , Esmalte Dentário/metabolismo , Animais , Cristalização , Difusão Dinâmica da Luz , Humanos , Microscopia de Força Atômica , Microscopia Eletrônica , Técnicas de Microbalança de Cristal de Quartzo , Transdução de Sinais
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA