Effect of Simulated Clinical Abrasion and Polishing Kits on Surface Roughness and Color Stability of CAD/CAM Restorative Materials after Coffee Immersion

To evaluate the effect of simulated clinical abrasion followed by manufacturer- recommended and universal chairside polishing kits on the surface roughness of various CAD/CAM restorative materials and on their color stability after coffee immersion.

A total of 80 specimens were analyzed for surface roughness and color stability. Specimens were fabricated from four CAD/CAM materials: lithium disilicate (IE), resin nanoceramics (SH, CS), and a polymer-infiltrated ceramic network (VE). All specimens were standardized, abraded using a fine-grit diamond bur, and polished with either manufacturer-recommended or universal polishing kits. Surface roughness was measured at baseline (Ra0), after abrasion (Ra1), and after polishing (Ra2). Color measurements were performed using a spectrophotometer, and color differences (ΔE₀₀) were calculated after 60 days of coffee immersion. Statistical analyses were conducted using paired t-tests and two-way ANOVA (α = 0.05).

Baseline roughness values were similar among groups (p > 0.05). Polishing significantly reduced Ra in all materials (p < 0.001). The reduction in roughness (ΔRa) was greater in the manufacturer-recommended groups than in the universal groups (p < 0.001), with the highest values observed in CS and SH. Both material type and polishing kits significantly affected color change (ΔE₀₀) (p < 0.001), with a significant interaction between the factors (p < 0.05). The lowest ΔE₀₀ values were recorded in IE, whereas the highest values were observed in SH.

CAD/CAM material type and polishing kits significantly affected surface roughness and color stability. Lithium disilicate showed the highest color stability despite the greatest roughness. Manufacturer-recommended polishing kits yielded lower roughness and better color stability than the universal kit.