Knoop hardness of composites due to three years of storage and depth

Abstract

The purpose of this research was to evaluate the Knoop hard- ness of 3 composites (Z100 A2, Silux Plus XL and Heliomolar RO 20) at times of 1 week, 1 month, 1 and 3 years on the irradiation and opposite surfaces. Specimens were obtained in 2.0mm thick poliacetal discs with perforations of 2.5mm diameter. Photoactivation was performed for 40 seconds with an intensity of 300mW/cm2. The con- clusions were: the opposite surface presented lower hardness values, either significantly or numerically; the comparison of hardness, corres- ponding to the time of 1 week and 3 years, showed a significant increase only for Heliomolar RO, but all the materials presented good compatibility when stored in a 0.9% NaCl solution; the hard- ness of the opposite side did not present convergence with that of the irradiated side. Key words: composite resin, Knoop hardness.