Effect of Four Bleaching Regimens on Color Changes and Microhardness of Dental Nanofilled Composite

Abstract

Objective . The purpose of this study was to compare the color changes and microhardness of a nanocomposite after four bleaching regimens. Materials . Twenty-five specimens ( n = 25 ) were made with a nanocomposite resin (Filtek Supreme XT). The specimens were divided into five groups equally ( n = 5 ) : bleaching groups and control group, as follows: G1: artificial saliva at 37 ∘ C; (control) G2: hydrogen peroxide (HP) at 7%; G3: hydrogen peroxide (HP) at 35%; G4: carbamide peroxide (CP) at 10%; G5: carbamide peroxide (CP) 35%. Color measurements were made with spectrophotometer using CIELAB color scale. The Vickers hardness (VHN) measurements were performed at the top surface. The data were analyzed with two-way Analysis of Variance. Results . Δ E and VHN mean values into the groups were not statistically different, however, the VHN mean values before and after storage and bleaching showed statistically significant differences. Conclusion . Nanocomposite samples showed no significant alteration (color and microhardness) after bleaching. Thus, no replacement of restorations is required after bleaching.