Efecto de la energía de polimerización sobre la resistencia flexural y módulo elástico, en composites envejecidos por UV

Abstract

The effect of the energy density on the immediate mechanical properties of composites is well known; although the relationship, between energy density and the time of degradation by UV, on flexural strength and elastic modulus is not clear. The aim of this study was to in vitro evaluate the flexural strength (σ) and the elastic modulus (E), as a function of accelerated aging under UV exposure on specimens prepared with different energy densities. Four resin composites were used in this study; F. Z-250, F. Supreme (3M ESPE), Tetric Ceram and Tetric EvoCeram (Ivoclar Vivadent), from each material, 60 specimens were divided in three groups: A (3.75 J/cm2 ), B (9 J/cm2 ) and C (24 J/cm2 ) and subdivided in: 1(no aging), 2 (500 hours of aging), 3 (1000 hours of aging) and 4 (1500 hours of aging). The results were analyzed by means of ANOVA and Tukey tests (p< 0.05) to determine the effect of the factors. Significant differences were found on flexural strength in subgroups: 1 (125 MPa), 2 and 3 (117 and 116 MPa) as well as in 4 (106 MPa). Significant differences were observed in the elastic modulus, between subgroups in Tetric Ceram and Tetric EvoCeram: 1 (8.0 GPa), 2 and 3 (10.2 GPa) and 4 (11.6 GPa); in the other hand, F. Z-250 and F. Supreme showed significant differences in subgroups: 1 and 3 (11.1 y 11.5 GPa), 2 (12.9 GPa) and 4 (13.5 GPa).