Effect of thermal cycling and microhardness on roughness of composite restorative materials

Abstract

Objective: This study is aimed to investigate the effect of thermal cycling and microhardness on surface roughness of four different composite restorative materials. Materials and Methods: In this study Nonofilled(Ivoclar Heliomolar, 3M ESPE Filtek Supreme) and microhybrid(3M ESPE Filtek Z250, Kuraray Clearfil AP-X) composites were used. The surface roughness (Ra) was initially measured in a profilometer using a cut off 0,25mm, after 6000 and 12000 thermal cycles. In addition to microhardness of composites Vicker hardness (HV) were determined. Data were subjected to Anova and Tukey′s test.(α=0,05). Results: One-way Anova indicated significant differences in Vicker hardness(HV) between four composite resins. Significant lowest HV was found for Heliomolar (HV=22); mean values were considerably lower than three composite resins. In addition to overall 6000 thermal cycles increased the surface of roughness values for all materials and there was a trend in all groups to decrease the roughness after 12000 thermal cycles. Conclusion: The material composition including type of organic matrix could be more relevant to roughness maintenance over time than the general behavior of composites based on particle fillers. Moreover, this study revealed that correlations between microhardness (HV) and surface of roughness were poor.