Effect of Different Surface Finishing Processes on the Optical Properties of Zirconium Oxide Ceramics

Abstract Objective: Zirconium oxide ceramics are widely used in dentistry due to their excellent mechanical and aesthetic properties. This study investigated the optical properties of zirconium oxide specimens applied with different surface finishing processes Materials and Methods: The study was conducted under in vitro conditions. Thirty zirconium oxide discs (diameter = 15 mm, thickness = 1.2 ± 0.2 mm) were produced and randomly divided into three groups: glazing (Control, Group C), grinding and polishing with EveDiacera (Group L), and grinding and polishing with a polishing paste (Group P). L, a*, and b* values were measured with a spectrophotometer, and color difference (ΔE00), translucency parameter (TP), whiteness index (WI), and modified metameric index (M-MI) were calculated. Data were analysed using ANOVA, Tukey HSD, paired t-tests, and Mann-Whitney U tests (p<0.05). Results: The mean ΔE00 values were 2.04 for Group C, 2.15 for Group P, and 1.81 for Group L. No significant differences were observed in ΔE00 among the groups (p>0.05). Post-treatment TP values significantly decreased in Groups P and L (p<0.001), and a significant difference was found between Group C and Group L (p=0.0017). WI values did not differ significantly between groups (p>0.05), although Group L showed a significant reduction after treatment (p=0.036). No significant differences in M-MI were observed under 4200K (p=0.112) or 5000K (p=0.325) illumination. Conclusion: Different surface finishing processes affect the translucency and whiteness of zirconia, while metamerism remained unaffected under various lighting conditions.