Effect of Successive Bleaching Treatments Followed by Staining on Color, Whiteness, and Translucency of Polymer-Based...

To evaluate differences in color, whiteness, and translucency of CAD-CAM materials after successive bleaching treatments and coffee immersion.

Lava Ultimate (LU) and VITA Enamic (VE) were divided into four groups (n = 12): untreated (control), 35% hydrogen peroxide (WH), 10% carbamide peroxide (OP), or WH followed by OP (WHOP). Color measurements were taken at baseline (T ₀) and after three consecutive bleaching sessions, each followed by coffee exposure (T ₁, T ₂, and T ₃). Differences in color (ΔE ₀₀), whiteness (ΔWI_D), and translucency (ΔRTP₀₀) were statistically analyzed for each material using two-way ANOVA and Bonferroni's tests and interpreted based on their respective perceptibility and acceptability thresholds. Surface topography was assessed by scanning electron microscopy.

For LU, there were no differences in ΔE ₀₀ and ΔWI_D among bleaching treatments. The second and third sessions increased ΔE ₀₀ and ΔWI_D values. The WH showed the greatest imperceptible ΔRTP₀₀. In VE, no treatment increased ΔE ₀₀, and only OP showed higher ΔE₀₀ in T ₃-T ₀ compared with T ₁-T ₀, but it was still imperceptible. All treatments decreased ΔWI_D in T ₂-T ₀ and T ₃-T ₀, with no significant differences in ΔRTP₀₀ compared with control. Except for WHOP, there were no statistical differences among sessions for ΔRTP₀₀. Only WH in VE did not result in topographic changes.

Successive bleaching treatments and coffee immersion resulted in imperceptible or deemed acceptable color, whiteness, and translucency changes of LU and VE.

Despite the surface topographic changes, all the bleaching methods tested in up to three sessions each followed by exposure to coffee did not adversely affect the esthetic durability of Lava Ultimate and VITA Enamic CAD-CAM materials.