The Effect of Bleaching on the Color Stability and Microhardness of Tooth-Colored Restorative Materials

Aims: This study investigated the effect of two home- bleaching regimens (7.5% hydrogen peroxide, 16% carbamide peroxide) on the color change and microhardness of microhybrid composite (Compo-san) and hybrid composite (TetricCeram) and RMGIC (Vivaglass). Materials and Methods: Thirty six disk – shaped specimens (5 × 2 mm)(of each restorative material for each test) were prepared and di-vided into three subgroup (n = 12).An unbleached group was used as control, while the remaining spec-imens in the two subgroups were bleached with bleaching regimens . Color change was assessed by using Vita Easy shade device , and the microhardness was determined by a Vicker,s microhardness tester. Means values were compared statistically with one way analysis of variance (ANOVA) followed by Duncan's Multiple Rang Test to determine the significant differences among the tested groups at (p = ≤ 0.05 )level of significance. Results: TetricCeram displayed unacceptable color change after bleach-ing with(16% carbamide peroxide) bleaching regimen. Decreasing in microhardness of Vivaglass after bleaching regimens, and microhardness of Composan after16% carbamide peroxide. Conclusion: The 16% carbamide peroxide bleaching regimen has significant effects on color change of TetricCeram and decreasing microhardness of Vivaglass and Composan restorative materials.