The Effect of Dental Bleaching on Surface Roughness and Microhardness of three Different Filler Types of Composites (An in vitro Study)

Aim: This study looked at the effects of in-office bleaching on surface microhardness and roughness of three composite resin materials: Nano filled, Nano hybrid, and Supra-nano spherical resin composite. Methods: A total eighty-four discs-like of nano filled, nano hybrid, Supra-nano spherical resin composite restorations were divided into two main groups for microhardness and surface roughness tests. Then, according to the type of composite, each main group was separated into three subgroups. Before and after bleaching with 32 percent hydrogen peroxide, the surface roughness and microhardness of all samples were assessed. The microhardness was measured by using Vickers tester, and a mechanical 2D profilometer surface roughness tester was used to measure the surface roughness. Repeated measures ANOVA and post hoc Tukey's test (alpha=0.05) were used to evaluate the data. Results: After bleaching for surface roughness, the data demonstrates a statistically significant difference between the three tested groups, as well as a statistically significant difference between the three tested groups after bleaching for microhardness. Conclusion: The application of bleaching substance increased the surface roughness and lowered the surface hardness of the three tested groups.