[Comparison of color change of silorane and methacrylate-based composites due to bleaching]

Bleaching treatments may alter the color stability of composite restorations. Silorane-based composites have shown similar or superior physical and mechanical properties compared to other types of composites. Furthermore, studies have shown variable and sometimes contradictory results regarding the effect of bleaching agents on the color stability of composite restorations. This study aimed to assess the effect of two Iranian bleaching agents on color stability of a Silorane-based [P90] composite compared with two methacrylate-based composites [nanofiller[Z350] and microhybrid. [Z250]. In this in vitro study, a total of 18 disc-shaped specimens [10 x 2 mm] of Z250, Z350 and P90 composites [A3 shade] were fabricated and randomly divided into 3 groups [n=6] and subjected to bleaching treatment with 16 % carbamide peroxide, 35% carbamide peroxide and distilled water as the control group. Color parameters were measured using CIE-L*a*b* system and a spectrophotometer before and after bleaching. The factors were statistically analyzed by means of two-sided ANOVA [repeated measures ANOVA] and Tukey's multiple comparisons tests.The mean +/- standard deviation of total color change [delta E] in control, 16% carbamide peroxide and 35% carbamide peroxide groups was 3.48 +/- 1.43,4.55 +/- 1.7 and 4.17 +/- 1.9, for Z250, 4.33 +/- 2.41, 4.94 +/- 2.23 and 4.25 +/- 1.65, for Z350 and 4.97 +/- 2.47, 5.28 +/- 1.67 and 3.4U2.26 for P90, respectively. delta E was clinically perceptible after bleaching treatments of all composite materials [delta E>3.3]