Effect of Surface Finishing Methods and Aging on Surface Roughness and Optical Properties of Zirconia-Reinforced Lithium Silicate Glass-Ceramic

Abstract

ABSTRACT Objectives: The effects of three different surface finishing methods and aging on the surface roughness and optical properties of zirconia-reinforced lithium silicate (ZLS) glass-ceramic were investigated. Materials and Methods: Rectangular specimens (0.6 mm thickness) were sliced from ZLS blocks (N=36). Three different types of surface finishing [glazing combined with crystallization (ZLS-CF) or after crystallization (ZLS-G) and polishing (ZLS-P)] (n=12) and 5000 thermocycles were applied. Three sets of measurements were performed before and after aging to determine the color coordinates and surface roughness (Ra) by using a colorimeter and profilometer, respectively. The mean surface roughness (Ra) values were calculated. Color differences and translucency parameter (TP) values were calculated using the color difference ΔEab and TP formulas. ANOVA was used to analyze the color difference, translucency, and surface roughness values (α=.05). Results: Significant differences in the ΔE values were not observed (P=.736) for specimens with different types of surface finishing. A significant difference was observed between the translucency values for different surface finishing groups before aging (P<.001). A significant difference in the surface roughness data between samples with different kinds of surface finishing was observed both before and after aging (P<.001). The ZLS-P group exhibited lowest surface roughness values before and after aging (P<.001). A positive significant correlation between the ΔE and translucency change values was observed in both the ZLS-G (P=.005) and ZLS-P (P<.001) groups. Conclusions: The surface finishing type did not affect the color change of ZLS glass-ceramic. The translucency values for different surface finished ZLS glass-ceramic specimens changed before aging. After aging, the surface finishing did not affect the translucency of ZLS glass-ceramic. All tested groups exhibited surface roughness values higher than the plaque accumulation threshold (Ra=0.2 mm).