Efeito da Degradação Química sobre a Rugosidade Superficial e Estabilidade de Cor de Resinas Compostas Micro-híbrida e Nanoparticulada / Effect of Chemical Degradation on Surface Roughness and on Color Stability of Micro hybrid and Nanofilled Composites

A resina composta é o material restaurador mais utilizado atualmente. Apesar de seu sucesso clínico, o material está sujeito a alterações em suas propriedades físicas, quando exposto ao meio bucal. O objetivo foi avaliar a influência da degradação química na estabilidade de cor e na rugosidade superficial de resinas micro-híbrida e nanoparticulada. Foram confeccionados 40 discos (6,0mm x 2,0mm) da resina composta micro-híbrida (Z250XT) e 40 da resina nanoparticulada (Z350XT). Após a análise da cor inicial e da rugosidade inicial, 10 discos de cada resina foram imersos em saliva artificial (Controle, pH=6,4), suco de laranja (pH= 3,4), refrigerante de limão (pH=2,9) e vinho tinto (pH=3,1), por 4 horas por dia (37ºC) durante 30 dias. Após, foram realizadas as leituras finais de cor e rugosidade. Os dados obtidos para a estabilidade de cor foram analisados pelo Teste de Kruskal-Wallis, seguido pelo Teste de Dunn (α=5%). Para a análise da rugosidade foi utilizado o Teste t para amostras pareadas (α=5%). O manchamento provocado pela saliva artificial, suco de laranja e refrigerante foi similar, mas foi estatisticamente diferente do manchamento produzido pelo vinho, em ambas as resinas testadas. O vinho produziu o mesmo grau de manchamento nas resinas micro-híbrida e nanoparticulada. Foi observado que o suco de laranja, o refrigerante e o vinho promoveram aumento da rugosidade superficial dos discos de resina. Diante disso, concluiu-se que o vinho alterou a cor de resinas compostas micro-híbrida e nanoparticulada, e que a rugosidade superficial dos discos de resina foi alterada por todas as bebidas utilizadas. (AU).

Composite resin is the most used restorative material. Despite its clinical success, it is susceptible to changes in its physical properties when exposed to the oral environment. The aim was to evaluate the influence of acidic beverages on the color stability and on the surface roughness of the nanofilled and micro hybrid composite. Forty discs (6.0mm x 2.0mm) of the micro hybrid composite (Z250XT) and 40 of the nanofilled composite (Z350XT) were manufactured. After the measurement of the initial color and the initial roughness, 10 discs of each composite were individually immersed in artificial saliva (control, pH = 6.4), orange juice (pH=3.4), lime soda (pH = 2.9) and red wine (pH = 3.1) during 4 hours per day at 37°C for 30 days. At the end of the experiment, the final analysis of color and surface roughness were performed. The data obtained for the color stability were analyzed by Kruskal-Wallis and Dunn's test (α= 5%). For the analysis of the surface roughness, the t test for related samples was used (α= 5%). The color changes promoted by artificial saliva, orange juice and soda were similar, but they were statistically different from staining produced by wine, in both tested composites. Wine produced the same degree of staining in both composites. Orange juice, soda and red wine increased the surface roughness of the composite discs. It was concluded that red wine significantly changes the color of micro hybrid and nanofilled composites. Furthermore, all beverages increased the surface roughness of the composites tested in the study herein. (AU).

Effects of different desensitizing treatments on root dentin permeability.

The objective of this study was to evaluate the effects of diode laser and a desensitizing dentifrice on dentin permeability. Fifty-two root dentin fragments were obtained (5 × 5mm) and treated with 24% EDTA gel. The samples were divided into 4 groups (n = 13): G1, control (no treatment); G2, diode laser (λ = 908 nm, 1.5 W, continuous mode, 20s); G3, application of abrasive dentifrice for 1 minute (Elmex Sensitive Professional (International Gaba); and G4, application of abrasive dentifrice for 1 minute followed by irradiation with diode laser. Ten samples per group were immersed in 2% methylene blue solution for 4h. The specimens were washed, longitudinally sectioned, observed under optical microscopy, photographed and assessed based on the degree of dye leakage. The remaining samples were observed under scanning electron microscopy (SEM). The leakage data were subjected to ANOVA test, followed by Tukey's t-test (α = 5%). Groups 2, 3 and 4 showed less dye penetration than the control group (p < 0.05), but were similar among each other. SEM images showed that dentinal tubules were open in G1, and fused and occluded in G2. Group 3 showed dentinal tubules that were occluded by the metal ions from the toothpaste. G4 presented similar characteristics to G3, and the presence of fused dentin. The diode laser and the dentifrice were effective in reducing dentinal permeability, and the combination of the two treatments did not show better results than either one used alone.

Effects of different desensitizing treatments on root dentin permeability

Abstract The objective of this study was to evaluate the effects of diode laser and a desensitizing dentifrice on dentin permeability. Fifty-two root dentin fragments were obtained (5 × 5mm) and treated with 24% EDTA gel. The samples were divided into 4 groups (n = 13): G1, control (no treatment); G2, diode laser (λ = 908 nm, 1.5 W, continuous mode, 20s); G3, application of abrasive dentifrice for 1 minute (Elmex Sensitive Professional (International Gaba); and G4, application of abrasive dentifrice for 1 minute followed by irradiation with diode laser. Ten samples per group were immersed in 2% methylene blue solution for 4h. The specimens were washed, longitudinally sectioned, observed under optical microscopy, photographed and assessed based on the degree of dye leakage. The remaining samples were observed under scanning electron microscopy (SEM). The leakage data were subjected to ANOVA test, followed by Tukey's t-test (α = 5%). Groups 2, 3 and 4 showed less dye penetration than the control group (p < 0.05), but were similar among each other. SEM images showed that dentinal tubules were open in G1, and fused and occluded in G2. Group 3 showed dentinal tubules that were occluded by the metal ions from the toothpaste. G4 presented similar characteristics to G3, and the presence of fused dentin. The diode laser and the dentifrice were effective in reducing dentinal permeability, and the combination of the two treatments did not show better results than either one used alone.