Effect of Different Surface Finishing Procedures on Color Stability of Leucite-reinforced Feldspathic CAD-CAM Ceramic

Statement of the problem: The color stability of newly introduced leucite- reinforced feldspathic CAD-CAM ceramic with different surface treatments remains unclear. Objective: This in-vitro study aimed to examine the effect of different surface finishing procedures on the color stability of leucite-reinforced feldspathic CAD-CAM ceramic. Materials & Methods: Twenty-four monochromatic, leucite-reinforced, A2-shaded feldspathic ceramic specimens prepared in 1 mm thickness. The specimens were randomly divided into 3 groups according to their surface finishing methods (n=8): a control group without surface finishing (Group C), surface finishing with polishing discs (Sof-Lex, 3M ESPE), and surface finishing with glaze (Group G). All the specimens were immersed in a coffee solution and kept in an incubator at 37 °C for 14 days. Initial color measurements were made with a digital spectrophotometer and the Commission Internationale de l'Eclairage (CIE) L*a*b* values were recorded. The color measurements were repeated at the ends of the 1st, 3rd, 7th, and 14th days with the spectrophotometer under the same conditions. The color change of the specimens was calculated with the CIEDE2000 (ΔE00) formula. Statistical analysis of the data was performed with a two-way mixed ANOVA and Bonferroni post-hoc tests (α=0.05). Results: Time and surface finishing procedures caused statistically significant color changes in the specimens (P<0.05). However, the interaction of time and surface finishing was not statistically significant (P>0.05). The lowest mean ΔE00 value was observed in Group G on day 14 (0.93 ± 0.74); the highest mean ΔE00 value was found in Group P on the 3rd and 14th days (2.16 ± 0.72). While the C and G groups exhibited similar color change values, Group P caused higher ΔE00 values compared to the glaze application (P<0.05). Conclusions: Based on the findings of this study, glaze application led to less color change compared with disk polishing. Glazing can be preferred to polishing to ensure long-term color stability in leucite-reinforced feldspathic ceramics.