An In Vitro Prosthodontic Evaluation of the Effect of Mouth Rinses on the Translucency of Monolithic and Multi-layered Yttria-Stabilized Zirconia

The aesthetic performance of zirconia restorations depends greatly on their optical properties, particularly translucency, which can be influenced by various chemical exposures in the oral environment. This in vitro study aimed to evaluate the effect of different immersion solutions on the translucency of two types of zirconia materials. A total of 30 zirconia specimens (n = 15 per group) were prepared: Group A comprised monolithic zirconia, while Group B consisted of multilayered yttria-stabilized zirconia. Each group was divided into three subgroups (n = 5) and immersed in one of three solutions: distilled water (DW), chlorhexidine (CHX), or 0% alcohol mouthwash. Translucency parameters (TP) were measured before and after immersion using a spectrophotometer based on the CIELab system. Statistical analysis was conducted using GraphPad Instat software with significance set at p < 0.05. The results revealed that immersion in CHX caused the most significant increase in TP change in both groups, with monolithic zirconia (Group A) showing the highest overall change. Two-way ANOVA indicated that the immersion solution had a statistically significant effect on translucency (p < 0.0001), while the type of zirconia showed no significant main effect (p = 0.0779). These findings suggest that translucency changes are more dependent on the immersion media than the zirconia composition itself. Clinicians should consider the long-term aesthetic implications of chemical exposure on zirconia restorations, especially when prescribing disinfectant mouthwashes