Evaluation the Effect of In-Office Bleaching On Color Changes On Restorative Composite Resins

This study evaluated the vitro performance of the effect of in-office bleaching (Zoom gel material) on the color changes of the one hundred twenty discs specimens, 5 mm in diameter and 2 mm thickness and shade color (A1). these were divided to three groups according to material which prepared from; Beautifil II (B), ISP Empress Direct (E) and Ceram. x. mono composite resins (C), each group's discs specimens were subdivided into four subgroups (n=10), according to the time follow up. All specimens? discs were polished and stored in distilled water at 37?C for one week. These specimens' discs were exposed later to four sessions of in office bleaching. The colorimetric measurements were performed at baseline (before bleaching), 48 hours after bleaching, 3 months and 6 months after bleaching. Data statistically analyzed. Results showed: there were significant effects on the different color parameters L*, a* and b* according to the CIE L* a* b* color system and color change (?E) on the specimens of the three contemporary composite resins materials.