Effect of different concentrations of carbamide peroxide on the staining susceptibility of resin composites

CONTEXT: Bleaching can affect the surface properties of resin composites. AIMS: The aim of this study was to evaluate the effect of three regimens of carbamide peroxide (CP) on staining susceptibility of silorane and methacrylate-based resin composites. METHODS: In this study, 80 composite disks were prepared from A2 shade of P90 and Z250 composite resins (40 each). Samples were divided into three test groups based on the CP concentration (10%, 16%, and 22%) and bleached for 14 days. Controls were kept in distilled water. Then, specimens were immersed in a tea solution for 14 consecutive days. A spectrophotometer was used to measure the specimen colors in CIE L*a*b system, initially and after staining. Data were analyzed using SPSS 16 software using two-way ANOVA, t-test, and Tukey honestly significant difference tests at α = 0.05. RESULTS: The color susceptibility of Z250 samples were significantly affected in groups bleached with 22% CP compared to the controls (P = 0.001). The different concentrations of CP did not affect the staining susceptibility of the P90 samples (P > 0.05). CONCLUSIONS: Bleaching of the tested resin composites did not increase their susceptibility to extrinsic staining in vitro except for the Z250 samples bleached with 22% CP.