Color Stability of Multi-Layered Zirconia Versus Lithium Disilicate Glass Ceramic: An in Vitro Study

Introduction: Patients who receive ceramic restorations use daily oral care products or plaque-control agents, which may cause discoloration of these restorations. The present study assessed the color stability of multi-layered zirconia and lithium disilicate pressable ceramic after 28 days of immersion in chlorhexidine, coffee, and soda. Methods: A disc measuring 2 mm in thickness and 10 mm in diameter was designed to fabricate 30 discs, divided into two groups based on the ceramic material: multi-layered (ML) zirconia and lithium disilicate (LD). Each group was further subdivided into three subgroups based on the staining solution: chlorhexidine, Cola, and coffee. The samples were immersed in staining liquids at room temperature for 28 days. Color was measured immediately at t0 and every week (t1 , t2 , t3 , and t4 ) using a spectrophotometer. Color changes were calculated. For pairwise comparisons, the Friedman test was first employed, followed by post hoc tests. Results: The greatest ∆E was observed in LD specimens immersed in chlorhexidine (5.65), followed by LD specimens immersed in coffee (5.44). The lowest ∆E was observed for ML zirconia specimens immersed in coffee (0.64). Significant differences were observed between ∆E values of all tested groups and subgroups (P≤0.05). Conclusion: ML zirconia exhibited significantly higher color stability than LD pressable ceramic after being subjected to simulated 28 months of beverage consumption and using chlorhexidine. Clinical Significance: Multi-layered zirconia exhibited higher resistance to discoloration than lithium disilicate pressable ceramic. Dental professionals should inform patients about the effects of chlorhexidine, Cola, and coffee on lithium disilicate pressable restorations.