The Effects of Office Bleaching Techniques on Nanoceramic Composite Resin

Objective: The aim was to evaluate the effect of activated bleaching agents on the nanoceramic composite resins based on microhardness and surface roughness measurements. Methods: Opalescence Boost (Ultradent Products, USA) and Whiteness HP Blue Calcium (FGM Dental Products, Brazil) bleaching agents and a nanoceramic composite resin Ceram.X® SphereTEC™ One (DENTSPLY, Germany) were used in the study. Fifty composite samples in disc form (8x2mm) were prepared. The samples were polished with discs (Sof-Lex, 3M Dental Products, St.Paul, USA) and incubated in the dark in distilled water. Samples were divided into 5 main groups (n=10). Control group (C), Opalescence Boost/ without light (OB), Opalescence Boost/ with light (OBL), Whiteness HP Blue/ without light (WB), and Whiteness HP Blue/ with light (WBL). Surface roughness (Ra) and Vickers microhardness (VHN) measurements were conducted after the bleaching process. Statistical analyses were performed using the Kruskal Wallis – H test and the Mann Whitney – U test; a p value of < 0.05 was considered statistically significant. Result: The VHN was significantly different among groups in terms of the application of bleaching agents and light (p = 0.008). The Ra was not significantly different among groups with respect to the application of bleaching agents or lighting conditions (p = 0.144). Conclusion: Within the conditions of this study, after bleaching procedure the microhardness values of the nanoceramic composite increased, however bleaching did not show any effect on surface roughness.