Effect of Applying Mouthwashes with an Oral Irrigator on Surface Roughness of Nanohybrid Resin Composites

Objective: This study aimed to evaluate the effects of different mouthwashes, applied either directly or via an oral irrigator, on the surface roughness of stained nanohybrid single-shade resin composites Materials and Methods: Two hundred disk-shaped specimens (8×2 mm) were prepared from two nanohybrid single-shade resin composites (Charisma Diamond One and Vittra APS Unique). All specimens were immersed in a coffee solution (3 g/50 mL) for 12 days to simulate one year of staining. Half of the specimens were treated with direct mouthwash immersion for 12 hours, while the other half were exposed to mouthwash solutions delivered using an oral irrigator for 40 seconds. Each method included subgroups (n=10) treated with distilled water, Sensodyne Pronamel, Listerine Fresh Burst, Colgate Plax White+Charcoal, and Crest 3D White. Surface roughness (Ra, µm) was measured using a profilometer at baseline, after staining, and following mouthwash application. Data were analyzed at p<0.05 level by using Robust ANOVA and Bonferroni post-hoc tests (α=0.05). Results: Coffee staining significantly increased surface roughness compared to baseline (p<0.001). Mouthwash applications reduced roughness compared to the stained condition, but values remained above baseline (p<0.05). No significant difference was found between the application methods (p>0.05). All mouthwashes produced similar surface roughness changes (p>0.05). Conclusion: Colored beverages increase the surface roughness of nanohybrid single-shade resin composites used in this in vitro study. Mouthwashes reduced roughness in stained specimens but did not restore surfaces to original smoothness. Oral irrigator use did not significantly affect the outcome compared to direct application. Mouthwash and dietary habits should be considered in restorative material selection.