Effect of Different Bleaching Methods on Optical Behaviors of CAD/CAM Ceramics

Background: The present study aimed to survey the influence of two different bleaching techniques on changes of color, translucency, and whiteness of the four CAD/CAM materials.Methods: The monolithic blocks of Vita Suprinity, Vita Enamic, IPS e.max CAD, and Katana Zirconia were sectioned to discs with thickness of ۲ mm (n = ۳۰ / each group). Samples from each type of ceramic were assigned to three subgroups: ۱) the ۴۰% hydrogen peroxide for ۲۰ minutes; ۲) the ۱۶% carbamide peroxide for three hours/day for ۲ weeks; and ۳) the control. Then CIELab coordinates of each sample were evaluated before and after the intervention by a spectrophotometer. Final color change (ΔE), Whiteness (ΔWI D), and Translucency Parameter (ΔTP) were calculated. Two-way ANOVA test was adopted to analyze the data (α = ۰.۰۵).Results: Type of ceramic, bleaching subgroups, and interaction between them had a statistically significant influence on mean values of ΔE, ΔWID. The influence of bleaching subgroup on the mean value of ΔTP was also significant (P < ۰.۰۰۱).Conclusions: Carbamide peroxide ۱۶% for three hours/day and for two weeks caused the most considerable changes in final color, whiteness, and translucency of the all tested CAD/CAM materials. Maximum color change and whiteness were detected in the Vita Enamic, which were clinically unacceptable.

Keywords:

Optical behaviors , Bleaching , CAD/CAM