Effect of surface treatment and surface region on the color stainability of a cemented high-translucency monolithic zirconia ceramic after coffee thermocycling.

STATEMENT OF PROBLEM

Restorations should show low color stainability after clinical and laboratory procedures; however, the impacts of surface treatment and surface region on the color stainability of zirconia restorations are unclear.

PURPOSE

The purpose of this in vitro study was to evaluate the effect of surface treatment and surface region on the color stainability of a cemented high-translucency monolithic zirconia ceramic after coffee thermocycling.

MATERIAL AND METHODS

Thirty high-translucency Ø10×0.5-mm monolithic zirconia disk specimens were divided into 3 groups based on the surface treatment applied: adjusting (A), polishing (P), and glazing (G). Specimens were cemented to composite resin backings and given 10 000 thermocycles in a coffee solution. CIELab values were measured with a spectrophotometer before and after thermocycling in central and marginal surface regions. ΔE values were calculated and compared with perceptibility (ΔE=0.8) and acceptability (ΔE=1.8) thresholds to interpret the color changes due to coffee thermocycling. Repeated measures ANOVA and Bonferroni tests were used for data analysis (α=.05).

RESULTS

Mean ΔE values ranged between 0.72 and 1.26. The surface treatment significantly affected the ΔE (P=.005); however, the surface region (P=.499) and the interaction of surface treatment and surface region (P=.998) did not affect the ΔE. The mean ΔE values were less than 0.8 for group G, but greater than 0.8 and less than 1.8 for groups A and P.

CONCLUSIONS

Glazing provides the lowest color stainability for cemented high-translucency monolithic zirconia, inducing imperceptible color changes after coffee thermocycling.