Objectives: The color stability of dental restorative materials must be maintained over their functional lifespan to preserve the esthetic integrity of the restoration. However, the regular use of mouthwash may impact their color. Therefore, this study aimed to assess the effects of two commercially available types of mouthwash with different compositions on the color stability of nano-hybrid CAD-CAM blocks.

Methods: Thirty square samples of 1 mm thickness were constructed from nano-hybrid CAD-CAM blocks (CERASMART, GC, Tokyo, Japan). Samples were randomly divided into 3 groups (n=10) according to the oral rinse solutions; Control group: distilled water (DW), group I: Tantum Verde and group II: Hexitol. Samples were incubated for 24 hours in the investigated solutions. The alteration of color resulting from immersion in various solutions was assessed utilizing a spectrophotometer. The values of color change (?E) were subsequently calculated. Data were analyzed using one-way ANOVA (?=0.05). Tukey’s HSD post-hoc was used for pairwise comparison.

Results: There were significant differences in ?E of CERASMART samples exposed to a range of immersion media (p<0.001). Tantum Verde showed the highest ?E values. Both investigated mouthwashes showed non-significant differences when compared to each other. ?E values for both mouth rinses showed a significant difference when compared to the control group.

Conclusion: Extended use of mouth rinses has the potential to induce color changes in hybrid composite CAD-CAM materials. Therefore, mouth rinses containing ethanol and alcohol should be advised with caution for daily use, especially with nano-hybrid CAD-CAM restorations.