The Evaluation of the Effect of Coffee Staining and 16% Carbamide Peroxide Bleaching on the Color Change of Chairside CAD/CAM Ceramics

Introduction: The aim of this study was to evaluate the effect of coffee staining and home bleaching agent on the color stability of stained CAD/CAM ceramics.Methods: Forty specimens were prepared from feldspathic ceramic (CEREC Blocs) and hybrid nano-ceramic (Cerasmart) CAD/CAM blocks (N=40). The polished specimens were ultrasonically cleaned in distilled water and then, immersed in coffee for seven days. The stained specimens were divided into four subgroups (n=10) according to their type of ceramic and bleaching treatment; CEREC control, CEREC bleaching, Cerasmart control and, Cerasmart bleaching. The home bleaching agent (Opalescence PF 16%)  was applied to specimens of bleaching groups for seven days. Control groups did not take any bleaching procedure and were placed in distilled water during this period. Then the specimens were immersed in coffee for seven days again for staining susceptibility. CIELAB parameters were recorded at four times; initial color, 1-week coffee staining, after bleaching, and coffee staining after bleaching with a dental spectrophotometer (VITA Easyshade). Color changes between each step were calculated as ΔE values. The data were statistically analyzed with t-test and Kruskal Wallis test. Results: After 1-week coffee staining the highest ΔE values were obtained from Cerasmart (p<0.001). The bleached Cerasmart group showed significantly higher color change values compared to Cerasmart control and both CEREC groups (P<0.05). No significant differences were found between control and bleached groups in both Cerasmart and CEREC groups after coffee immersion.Conclusion: Coffee staining and 16% carbamide peroxide bleaching significantly influenced the color of resin ceramic CAD/CAM materials.