Abstract

This study evaluated the effects of 4 different bleaching agents with 2 different bleaching methods (2 in-office bleaching systems: 38%HP Opalescence Xtra Boost and 35% HP Beyond Maxx; 2 home bleaching systems: Opalescence PF 35% CP and Beyond 6% HP) on the micro hardness and surface roughness of 4 different resin composites (Aelite-hybrid, Grandio-nanohybrid, Clearfil Majesty-nano superfilled, Siloran-silorane based). One hundred square samples, with A3 shading, were prepared with 10 mm in diameter and 2 mm in depth. Samples were divided into 20 test groups (n=5). 5 samples of each of the 4 different resin composite samples were selected for baseline surface roughness measurements (with a non-contact, 3D, optical, surface profilometer) and surface micro hardness tests (with Vickers instrument) as control groups. The appropriate bleaching procedure was performed on the top surface of test groups for 14 days. Surface roughness and hardness were tested at the end of the duration. Statistical calculations were performed with NCSS 2007 program for Windows. The statistical significance level was established at p<0.05. Significance levels of the 4 treatments were as follows: Beyond home bleaching agent (p= 0.0005), Beyond office bleaching agent (p=0.0007), Opalescence home bleaching agent (p= 0.0005) and Opalescence Xtra Boost office bleaching agent (p=0.0006). After the exposure duration described above, there was a significant difference between the micro hardness of the tested composite groups. In response to exposure to beyond home bleaching agent, there was a significant difference among the surface roughness (Sa) within the tested composite groups (p=0.03). After exposure to Opalescence office bleaching agent, there is a significant difference between the surface roughness (Sa) of the tested composite groups (p=0.0007). Clinical relevance: The conditions of this study included a 2-week bleaching regimen with high peroxide, concentrated either in a dental office or at home. Bleaching agents affected the roughness and hardness of hybrids, nano hybrids, nano super filled, and silorane composites. Nano-based composites were affected less than the hybrids and siloranes.

Key words: Laser profilometer, micro hardness, nano-composites, siloranes, surface roughness.