BACKGROUND AND OBJECTIVE: One of the most reasons for composite restoration replacement is their color change. Bleaching can effect of color of composite restorations’ color. The aim of this study was evaluation the effect of 40% hydrogen peroxide on the color of 3 different composites

METHODS: In this in vitro study, 30 disk-shaped samples of Z250, Z350XT, and Heliomolar composites (10 mm diameter and  mm thickness) were prepared in A3 shade (n=10). Then samples were kept in distilled water for 24 hours. After that samples were exposed to 40% hydrogen peroxide (Opalescence Boost PF) for 40 minutes .the color of samples was measured immediately after preparing, after 24h and after bleaching and ∆E was recorded. The ∆E above 3.3 was considered clinically significant.

FINDINGS: The amount of color change in Z250, Z350 XT and Heliomolar were (DE=2.72), (DE=3.08) and (DE=2.40) the amount of ∆E were lower than 3.3. there were no significant diferences between composites according to effect of 40% hydrogen peroxide on their color change (p=0.15). after completion of polymerization the amount of ∆E was (2.28±0.29), (2.62±0.23) and (2.27±0.12) which were lower than 3.3. there were no significant differences between color change of different composites after 24 hours.(p=0.4).

CONCLUSION: 40% hydrogen peroxide has no effect on the color change of compsites which were evaluated in this study. Completion of polymerization does not make significant change in color of these composites.