Color change of direct resin-based composites after bleaching: An in vitro study

This in vitro study was designed to quantitatively evaluate and compare color changes in different types of direct resin-based composites including a silorane-based low-shrink resin composite, after bleaching with 10% carbamide peroxide.Fifty disc-shaped specimens (10/material) from five resin-based composites (Z250, Z350, Valux Plus, P90, and Dyract Extra) were fabricated in a cylindrical rubber mold (10 mm diameter × 2 mm depth) according to the respective manufacturers’ instruction. A spectrophotometer (Color Eye 7000A) against a white background using CIE (L∗a∗b∗) relative to a standard illuminate D65 was used to measure the color of specimens before bleaching procedure as baseline records and after bleaching procedure using (Opalescence PF-10% carbamide peroxide) 8-h daily for 14 consecutive days. The magnitude of color difference (between baseline and after bleaching measurements) is represented by ΔE. Data were subjected to a one-way ANOVA and Bonferroni multiple comparison test at 95% confidence level.The mean color change values (ΔE) were less than 1 and visually non-perceptible to the naked eye for silorane-based low-shrink composite (P90) as well as the other resin-based composites used in this study (nanofilled Z350, hybrid Valux Plus, and microhybrid Z250). Whereas, the mean color change value (ΔE) was higher than 1 and noticeable to the naked eye for polyacid-modified resin-based composite (Dyract Extra), yet considered clinically not significant.