Análise comparativa do desgaste de materiais odontológicos através de Tribômetro Callowear – ensaio “in vitro”

The aim of present study was to evaluate the wear coeficient of different dental materials submited to ballcrattering test. Different restorative materials were compared to bovine enamel. The samples were made with nylon matrix stripes and had 7mm diameter and 2mm thickness. The samples were submitted to the ballcratering test in a Calowear tribometer (CSEM Instruments Advanced Mechanical Surface Testing) and maded six measures in each sample with different revolutions of the ball: 10, 20, 30, 40, 50 and 60 revolutions. After the crattering generation the samples were avaliated to a Zeiss Axiotech Vario Microscope with SVGA Cam and all cratters photographed. After, the photos were evaluated at UTHSCSA ImageTool for Windows 3.0 and the meaning of measured radius were inserted at SigmaPlot, that gave the wear coefficients by linear regression. To bovine enamel the coefficient was 3,83 X 10-14 m²/N, to microhybrid resin was 3,6542 x 10-14 m²/N, 2,06 x 10-12 m²/N to amalgam and 2,18 x 10-12 m²/N to acrylic resin. In conclusion, bovine teeth presented higher wear resistance and lower wear coefficient than composite resin, amalgam and acrylic resin.O objetivo do presente estudo foi avaliar o coeficiente de resistência ao desgaste de diferentes materiais odontológicos submetidos ao ensaio de micro-abrasão através da metodologia de ball-crattering. Para isso foram avaliados diferentes materiais restauradores em comparação com o esmalte bovino. As amostras foram confeccionadas através de matrizes de nylon bipartida, com 7mm de diâmetro e 2mm de espessura em negativo e após, a resistência ao desgaste foi avaliada em um ensaio de micro abrasão (Ball cratering test) realizado em tribômetro modelo Calowear (CSEM Instruments Advanced Mechanical Surface Testing). Em cada corpo de prova foram feitas seis medições com variação no número de voltas realizadas pela esfera: 10, 20, 30, 40, 50 e 60 voltas. Após a realização das crateras o corpo de prova foi levado a um Zeiss Axiotech Vario Microscope com câmera SVGA acoplada onde foram fotografadas todas as crateras geradas e após, foram analisadas em UTHSCSA ImageTool for Windows versão 3.0, os valores de raio médio das marcas foram, então levados ao SigmaPlot versão 8.0 que através da correlação dos dados determinou o coeficiente de desgaste através de uma regressão linear. Para os corpos de esmalte bovino foi encontrado o coeficiente de desgaste de 3,83 X 10-14 m²/N, para resina composta micro híbrida 3,6542 x 10-14 m²/N, para amálgama de prata 2,06 x 10-12 m²/N e para resina acrílica autopolimerizável foi de 2,18 x 10-12 m²/N. Após a execução dos ensaios chega-se a conclusão que o esmalte bovino apresentou maior resistência e menor coeficiente de desgaste, seguido por resina composta, amálgama de prata e resina acrílica autopolimerizável

Development of experimental HEMA-free three-step adhesive system.

To evaluate the influence of Bis-EMA 30 on the resin-to-dentin microtensile bond strength (microTBS) and structural reliability of the experimental three-step etch-and-rinse adhesive systems.Five experimental primers containing different dimethacrylate monomer concentrations (0, 10, 20, 40, 60 wt% of the Bis-EMA 30, P0.P60) added to acid monomer and solvents (ethanol/water), and a resin bond (Bis-GMA/TEGDMA, 50/50 wt%) were formulated. The adhesive system Scotchbond MultiPurpose (SBMP, 3M ESPE) was tested as commercial reference. Sixty bovine incisors were randomly separated into six groups, and their superficial coronal dentin was exposed. After acid etching and rinsing, the excess water was removed from the surface with absorbent paper. Each experimental primer was actively applied (30 s), followed by a mild air stream (10 s). The experimental adhesive resin was applied and light activated for 20 s. Resin composite restorations were incrementally built up. The restored teeth were stored in distilled water at 37 degrees C for 24 h, and then sectioned to obtain sticks with a cross-sectional area of approximately 0.5 mm(2), after which 24 specimens per group were subjected to the microTBS test. Data (MPa) were analyzed by One-way ANOVA, Tukey test (alpha=0.05) and Weibull analysis.The P40 group showed microTBS means similar to those of the control (SBMP), whereas both had statistically higher values when compared with the other groups (p0.001). Moreover, P40 showed higher structural reliability, represented by the high Weibull modulus and characteristic strength values. The lowest microTBS was observed in the P0, P10 and P20 groups, which also had low structural reliability.Bis-EMA 30 is a promising monomer to be considered as a substitute for HEMA in adhesive system compositions

Bismuth subsalicylate as filler particle for an experimental epoxy-based root canal sealer

Aim: To evaluate the influence of bismuth subsalicylate addition in different concentrations on theproperties ofan experimental epoxy-based root canal sealer. Methods: Bismuth subsalicylate in 20%, 40%, 60%, 80%, 100% and 120 wt% was added tothe sealer. Flow, film thickness, working time, setting time, dimensional change, sorption, solubility and cytotoxicity were evaluated according to ISO standard. Data were statistically analyzed by one-way ANOVA and Tukey’stest with a significance level of 5% for all tests. Results: The flow, working and setting times significantly decreased withincreasing particle concentration. The film thickness, dimensional change, water sorption and solubility values significantly increased with higher particle amount. The results for cytotoxicity showed no statistically significant differences among the particle proportions. Conclusions: The results suggest that the addition up to 80% wt of bismuth subsalicylate appears to be a promising filler particle to root canal sealer development

Avaliação da resistência da união imediata à dentina de sistemas adesivos simplificados

Objetive: The aim of this study was to evaluate the microtensile-bond strength of four commercial adhesive systems. Methods: Twenty bovine incisors had the buccal dentin exposed and restorations were made using four different adhesive systems (n=5): Magic Bond DE and OptiBond Solo (two-step etch-and-rinse), One-Up Bond F and Adper Prompt L-Pop (one-step self-etch). Teeth were sectioned perpendicularly to the adhesive interface to obtain beams of 1mm² of section. The beams were submitted to microtensile-bond strength on a universal testing machine. Data were analyzed by one way ANOVA and Tukey post hoc at a 5% of significance. Results: The mean bond strength values were 48.81±0.56 to Magic Bond DE, 47.52±13.03 to OptiBond Solo, 44.68±13.32 to One-Up Bond F and 31.59±11.81 to Adper Prompt L-Pop. Adper Prompt L-Pop exhibited lower bond strength than etch-and-rinse adhesive systems (pObjetivo: Avaliar quatro sistemas adesivos comerciais de diferentes composições quanto ao desempenho da resistência da união à dentina. Métodos: Vinte incisivos bovinos tiveram a dentina vestibular exposta e receberam restaurações de resina confeccionadas com quatro (n=5) diferentes sistemas adesivos simplificados: Magic Bond DE e OptiBond Solo (convencionais), One-Up Bond F e Adper Prompt L-Pop (auto-condicionantes). Os dentes foram seccionados perpendicularmente a interface adesiva utilizando-se um disco de diamante, de modo a se obter palitos de 1mm² de área de secção. Os palitos foram submetidos ao ensaio de micro-tração em uma máquina de ensaios universal. Os valores médios de resistência de união dos diferentes sistemas adesivos foram comparados utilizando-se ANOVA de uma via e teste Tukey, em um nível de significância de 5%. Resultados: Os valores médios de resistência da união foram 48,81±0,56 para o Magic Bond DE, 47,52±13,03 para o OptiBond Solo, 44,68±13,32 para o One-Up Bond F e 31,59±11,81 para o Adper Prompt L-Pop. O adesivo Adper Prompt L-Pop apresentou resistência de união inferior a dos adesivos convencionais (

Resistência adesiva à microtração ao esmalte de um adesivo auto-condicionante simplifi cado: infl uência de múltiplas camadas

This study tested the null hypothesis that the number of applications of a self-etching primer would not infl uence the microtensile bond strength at the interface resin/enamel. Bovine teeth were fl atted to expose the prismatic enamel with wet 600 grit silicon carbide papers. The teeth were divided into two groups: FB 1coat, FuturaBond (Voco) applied according to the manufacturer’s instruction for 30 s; and, FB 4coats, applied four times, 30s each. Then, they were restored with Polofi l (Voco) resin composite. After 24h, samples were cut with a diamond low speed saw under water cooling to obtain stick-shaped specimens of approximately 0,5 mm2 cross-sectional area. The sticks underwent microtensile testing at a speed of 1 mm/min. The bond strength, in MPa, was: FB 1coat, 33.57 ±8.77 (18); FB 4coats: 33.57 ±8.77 (18). This values, at t student test, had not showed signifi cant difference (p=0.58). In this study, the number of coats did not interfere at the values of bond strength at the interface resin/enamel.Este estudo testou a hipótese nula de que o número de camadas de aplicação de um primer auto-condicionante pode não influenciar não resistência da interface adesiva resina/esmalte à microtração. Dentes bovinos foram niveladas, para expor os prismas de esmalte, utilizando-se lixa d´água #600. Os dentes foram divididos em dois grupos: FB 1 camada, FuturaBond (Voco) aplicado de acordo com as recomendações do fabricante por 30 s; e, FB 4 camadas, aplicadas quatro vezes, 30s cada. Foram então restaurados com a resina composta fotopolimerizável Polofil (Voco). Após 24 horas as amostras foram cortadas com um disco diamantado em baixa rotação sob abundante irrigação para obter palitos de aproximadamente 0,5 mm2 de área. Os palitos foram submetidos á microtração a uma velocidade de 1 mm/min. A resistência adesiva, em MPa, foi: FB 1 camada, 33.57 ±8.77 (18); FB 4 camadas: 33.57 ±8.77 (18). Esses valores, no teste t de student, não apresentaram diferença significativa (p=0.58). Nesse estudo, o número de camadas não interferiu nos valores de resistência de união da interface resina/esmalte

effect of the silane concentration on the selected properties of an experimental microfilled composite resin

The aim of present study was evaluate the effect of different percentages of an organo-functionalized silane monomer as adhesion promoter between barium borosilicate glass fillers and (co)monomer blend in experimental dental composite resin. Gamma-methacryloxypropyltrimethoxysilane (γ-MPS) was assessed in an experimental luting cement, at the concentrations of 0, 1, 3, 5, 7 and 10 (wt%). The experimental resin without fillers was used as control group. The flexural strength (FS) and elastic modulus (E) were obtained by mini-flexural test and expressed in MPa and GPa, respectively. Water sorption (WS) and solubility (SL) were determined based on ISO standard 4049:2000. Kruskal–Wallis and Student–Newman–Keuls test were used for comparisons of FS, E and WS. The comparisons of SL means were performed using one-way ANOVA and Tukey's method (α = 5 %). The treatment with 3 % silane revealed statistically higher FS, while the group treated with 1 % silane showed statistically higher E than 3 % silane (p < 0.05) and E similar to control. The experimental composite without filler content showed the highest SL (p < 0.05) while the control composite showed the highest WS (p < 0.05). Based on present findings, flexural strength and elastic modulus can sometimes be improved with lower concentrations (1–3 %) rather than higher concentrations (5–7 %) of the silane (γ-MPS) used as coupling agent on barium borosilicate glass filler microparticles of the dental composite resin