Color Stability and Surface Roughness of Cad/Cam Ceramic and Composite

Objectives: This study aimed to evaluate in vitro the effects of the immersion on staining solutions, with or without brushing, on surface roughness and color stability of leucite-reinforced glass-ceramic (IPS Empress^® CAD) and cross-linked dimethacrylate-based composite (Tetric^® CAD) used in prosthesis manufacturing through CAD/CAM technology.
Methods: Samples of ceramic and composite (40 units, each) were randomly assigned to immersion solutions (n=8): 1)Coffee; 2)Black tea; 3)Cola soft drink; 4)Red wine; 5)Distilled water. Surface roughness (Ra) and color stability (ΔE₀₀) parameters were evaluated before (T0) and after immersion (T1). Subsequently, the samples underwent brushing, and the parameters were reanalyzed (T2). Immersion and brushing simulated a 5-year period. Data analysis considered the variation found between T1-T0 (Δ1), and the variation T2-T0 (Δ2). Data were expressed as mean and standard deviation, subjected to the Shapiro-Wilk normality test, and compared using the three-way ANOVA test followed by Bonferroni post-test (p<0.05).
Results: In the ΔE₀₀ analysis, it was observed that all variables (material, solution, brushing) had statistical significance. The composite showed greater color changes than ceramic (p<0.001), and red wine solution promoted the most significant color changes, followed by tea and coffee (p<0.001). The most substantial color changes were observed in Δ1, demonstrating that brushing was able to remove some pigments. Black tea altered the color beyond the acceptability threshold (ΔE₀₀ 1.8), even after brushing, of the composite (3.70±1.11) and ceramic (2.79±1.01). This was also recorded in composite samples immersed in red wine (6.46±3.87). In the roughness analysis, only the variable “brushing” was statistically determinant (p=0.029).
Conclusions: It was concluded that brushing after immersion increased the roughness of the materials, but this increase was less than 0.2μm (acceptable for dental prostheses to prevent plaque accumulation). Color changes were more observed in the composite than in the ceramic, although the ceramic samples immersed in black tea showed significant color changes.