Evaluation of mechanical properties of Z250 composite resin light-cured by different methods

Abstract

); e). PAC (1320mW/cm 2 -3s); f). LED (350mW/cm 2 -40s). After 24 ± 1 h, the specimens were loaded at a crosshead speed of 0.5 mm/min until fracture. The mechanical properties were calculated and analyzed by ANOVA and Tukey test (5%). The results showed that the highest compressive strength values were found for the continuous, exponential, intermittent and stepped light methods, whereas PAC and LED obtained the lowest values. LED, stepped light, PAC, exponential and continuous light presented the highest values for diametral tensile strength. The intermittent light showed the lowest value, which was significantly lower than the value obtained for LED only. Flexural strength results were not significantly different between all light-curing methods. Finally, the highest modulus of elasticity values were obtained for LED, exponential, continuous and intermittent light, whereas PAC and stepped light showed the lowest values. The mechanical properties were affected by light-curing methods employed. Uniterms: Composite resins; Light-curing methods, Compressive strength; Diametral tensile strength; Flexural strength; Modulus of elasticity. ste estudo avaliou algumas propriedades mecânicas da resina composta Z250 usando diferentes métodos de fotoativação. Dez amostras foram preparadas para cada grupo, com diferentes dimensões de acordo com o ensaio. Os métodos de fotoativação foram: a) luz contínua (800mW/cm 2 -40s); b) luz exponencial (0-800mW/cm 2 -40s); c) luz intermitente (2s-600mW/cm 2 ; 2s sem luz80s); d) dupla intensidade (10s-150mW/cm 2 ; 30s-650mW/cm 2 ); e) PAC (1320mW/cm 2 -3s); f) LED (350mW/cm 2 -40s). Após 24 ± 1 h, as amostras foram carregadas até fraturar (v=0,5 mm/min.). As propriedades mecânicas foram calculadas e os dados analisados estatisticamente (ANOVA e teste de Tukey 5%). Os resultados mostraram que, para resistência à compressão, os maiores valores foram encontrados com os métodos luz contínua, intermitente, exponencial e dupla intensidade, enquanto que PAC e LED obtiveram os menores valores. Os métodos LED, PAC, luz contínua, exponencial e dupla intensidade, mostraram os maiores valores para resistência à tração diametral, enquanto luz intermitente mostrou os menores valores, que diferiram apenas do LED. Para a resistência flexural, não houve diferença entre os métodos. Já, para o módulo de elasticidade, os maiores valores foram obtidos com LED, luz exponencial, contínua e intermitente, enquanto que PAC e dupla intensidade mostraram os menores valores. As propriedades mecânicas podem ser afetadas pelo método de fotativação utilizado. Unitermos: Resinas compostas; Fotoativação; Resistência à compressão; Tração diametral; Flexão; Módulo de elasticidade. 393J Appl Oral Sci. 2005;13(4):393-8

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