Color Stability and Staining Susceptibility of Direct Resin-Based Composites after Light-Activated In-Office Bleaching

This study evaluated color stability and staining susceptibility of five direct resin-based composites (RBCs) subjected to light-activated in-office bleaching with 40% hydrogen peroxide (HP). The test materials included 5 RBCs, which consisted of one nano-filled, one sub-micron, one bulk-filled, and two nano-hybrid RBC types. Ten disc-shaped specimens of each RBC were fabricated and divided into bleaching (BLE) and non-bleaching (CON) groups (n = 5 for each group). Specimens were then immersed in red wine solution over 4 h. A spectrophotometer was used to obtain Commission Internationale de l'Eclairage (CIE) L*a*b* parameters for each of the following periods tested: before bleaching (T-BA), after bleaching (T-BL), and after staining (T-ST). Color stability and staining susceptibility were evaluated using two metrics, CIEDE2000 color differences (Delta E-00) and whiteness variations using the whiteness index (Delta WID). Data were analyzed using repeated measures two-way analysis of variance (ANOVA) (alpha = 0.05). Statistically significant and clinically unaccepted Delta E-00 and Delta WID were observed for all tested specimens between T-BA and T-BL. The nano-hybrid type RBCs showed the highest discoloration among materials after bleaching treatment. The BLE group exhibited significantly higher Delta E-00 and Delta WID than the CON group for all the tested RBCs between T-BA and T-ST. The sub-micron type RBC showed the highest discoloration among materials after immersion in the red wine. Conclusion. The light-activated in-office bleaching with 40% HP's influences on color and whiteness index were material-dependent. The use of bleaching treatment also increased the susceptibility to red wine for all RBCs.