Effect of stain brand and shade on color stability of stains applied on a CAD-CAM feldspathic ceramic

The aim of this study was to investigate the effect of stain brand and color on color stability of stains on a CAD-CAM ceramic after aging. Specimens (15 × 8 × 1.5 mm) were fabricated from A2-shade ceramic blocks (Mark II; Vita Zahnfabrik) (N = 120). Specimens were divided into two groups (n = 10) to be stained with six different stains (yellow, orange, blue, gray, violet, and brown) from two manufacturers (GC initial spectrum (GC) and IPS e.max Ceram (IPS)). Aging was performed for 5 h at 134 °C. Color coordinates before and after aging were measured to calculate color differences (ΔE₀₀). Kubelka–Munk absorption (K) and scattering coefficients (S) of stains were compared with those of A2 shade tab. Two-way ANOVA was used to analyze the ΔE₀₀ values and Tamhane T2 was used to analyze the K and S coefficients (alpha = 0.05). A significant interaction was found between stain color and brand (p < 0.001). Color changes with IPS stains were higher than those with GC stains except for brown. The highest color difference was with orange stain of IPS (p < 0.001). Absorption and scattering coefficients of different stains on CAD-CAM ceramic were different from those of A2 shade tab except for brown stain (p < 0.001). Tested stains on CAD-CAM ceramic had varying color changes after aging. Color of gray, violet and brown of both stains was stable. Yellow, orange, and blue GC stains were more color stable compared with IPS. Absorption and scattering coefficients of stains in different colors varied.