Roughness and Microhardness of Composites after Different Bleaching Techniques

Background The aim of this study was to evaluate the roughness and microhardness of SonicFill™ (Kerr), and compare it with Filtek™ Supreme XTE (3M ESPE) after 2 bleaching regimens. Methods Sixty cylindrical specimens (10 × 2 mm) of each of the 2 composites were prepared and divided into 6 groups (n = 20): groups 1, 2: no treatment; groups 3, 4: 10% carbamide peroxide (CP); and groups 5, 6: 35% hydrogen peroxide (HP) plus LED. After treatments, specimens were thermocycled (500 cycles, 5°C/55°C, dwell time 30 minutes). A mechanical roughness tester was employed to measure the surface roughness parameters and the Vickers test to measure microhardness. One-way ANOVA, Tukey and Bonferroni methods with a significance level of 5% were used for the statistical analysis. Results For SonicFill™, there was no statistically significant difference in microhardness between the control group (no. 1) and the bleached groups (nos. 3, 5), but there was difference between CP and HP treatments; for Filtek™ Supreme XTE, there was no significant difference in microhardness among all groups. There was no significant difference in average roughness (R _a ) and the root mean square of the roughness (R _q ) among all groups. The mean roughness depth (R _z ) parameter showed no statistically significant differences among all groups for SonicFill™, but in Filtek™ Supreme XTE, there was a significant increase between control and bleaching treatments; roughness skewness (R _sk ) showed no statistically significant differences among all groups for SonicFill™ and Filtek™ Supreme XTE, except for nos. 2 and 4, where the R _sk increased with CP. Conclusions The microhardness of Filtek™ Supreme XTE is less affected by bleaching than that of SonicFill™. Both bleaching treatments affect R _z in Filtek™ Supreme XTE in contrast to SonicFill™, but only the CP treatment affects the R _sk of Filtek™ Supreme XTE, with no significant effect of SonicFill™.