Influence of Beverage Immersion and Repolishing on the Color Stability of CAD/CAM Restorative Materials: An In Vitro Study

Long-term aesthetic success in dentistry largely depends on the color stability of restorative materials. This study investigated the color changes (ΔE00) of resin nanoceramic and lithium disilicate ceramic restorative materials used in computer-aided design and computer-aided manufacturing (CAD/CAM) systems following beverage immersion and after repolishing. One hundred specimens were prepared from lithium disilicate (Initial LiSi Block) and resin nanoceramic (Cerasmart), and polished. The specimens were divided into ten groups according to material and beverage type (n = 10) and immersed in distilled water, cola, tea, coffee, and turnip juice at 37 °C for 3 months. Color values were recorded at baseline, 1 week, 1 month, and 3 months, and after repolishing. ∆E00 values were calculated using the CIEDE2000 color difference formula. Data were analyzed using three-way repeated measures ANOVA and post hoc Tukey and Bonferroni tests (α = 0.05). Material type, beverage type, and immersion time significantly affected color stability (p < 0.05). The highest ∆E00 observed in the resin nanoceramic–tea group at 3 months (ΔE00 = 11.39 ± 1.76). Lithium disilicate demonstrated better color stability. After repolishing, all ΔE00 values were below the clinically acceptable limit (ΔE00 ≤ 1.8). Repolishing may help maintain the long-term aesthetic success of dental restorations in the oral environment.