Evaluation of color stainability of computer-aided design/computer-aided manufacturing blocks with different microstructures

The stainability of ceramic materials is a critical factor in the long-term esthetic success of computer-aided design/computer-aided manufacturing (CAD/CAM) restorations. This study aimed to evaluate the color stainability of CAD/CAM ceramic blocks with different microstructures after immersion in a coffee solution for varying durations. Three types of CAD/CAM blocks—Vita Mark II (MG), Vita Suprinity ([SG] and [SP]), and Vita Enamic (EP)—were used. Finishing and polishing were performed according to the manufacturers’ instructions. CIE L*, a*, and b* values were measured at baseline (T₀), and after 1 (T₁), 12 (T₁₂), and 30 (T₃₀) days of immersion in coffee using a spectrophotometer. Color differences (ΔE₀₀), ΔL\', ΔC\', and ΔH\' were calculated using the CIEDE2000 formula. One-way ANOVA was used to compare these values across materials. Multiple linear regression analysis was conducted to assess the influence of ΔL\', ΔC\', and ΔH\' on ΔE₀₀ (p<0.05). Statistically significant differences in ΔE₀₀, ΔL\', ΔC\', and ΔH\' values were observed at all time intervals (p=.000), except for ΔH\' between T₀-T₁₂ (p=.199). ΔL\' was the primary influencing factor for MG, SG, and SP materials, while ΔH\' had the greatest effect on EP over the T₀–T₃₀ interval. Within the limitations of this study, the chemical composition of the material influenced ΔE₀₀, ΔL\', ΔC\', and ΔH\' values. SG showed the lowest and clinically acceptable level of staining, while EP exhibited a moderate but clinically unacceptable degree of discoloration.