Effect of vital bleaching on surface roughness and microhardness of nanofilled and nanohybrid composite resins

Background: To compare the surface roughness and microhardness of Ceram.x® SphereTEC™ one and Filtek Z350 XT after in-office vital bleaching with Pola office. Methods: A total of 20 samples of 10 mm diameter and 2 mm height of Ceram.x® SphereTEC™ one and Filtek Z350 XT were prepared. The samples were subjected to two bleaching sessions with 35% hydrogen peroxide (Pola office) with a seven-day interval between each session. Surface roughness and microhardness of the prepared samples prior to and after the bleaching regimen were measured using a profilometer and Vickers hardness tester, respectively. Results: A significant reduction (p <0.001) in the surface hardness of Filtek Z350 XT from 26.67 ± 2.10 to 17.83 ± 1.36 Vickers hardness number (VHN) was observed after the bleaching whereas no significant reduction in surface hardness was observed with Ceram.x® SphereTEC™ one. However, in-office bleaching of these materials did not significantly alter their surface roughness. Conclusions: The effect of in-office bleaching on the surface hardness of resin composites seem to vary due to variations in the composition of dental composites such as filler loading. Among the composites tested, in office bleaching of Ceram.x® SphereTEC™ did not result in significant changes in its surface hardness and roughness.