Property changes in resin composite exposed to mouth rinses during 10% carbamide peroxide bleaching

Aim: This in vitro study evaluated the effects of different mouth rinses in combination with 10% carbamide peroxide bleaching gel on the properties of resin composite. Methods: Cylindrical specimens of a nanofilled resin composite (n = 12) were allocated to four groups: distilled water (control, C), mouth rinse with essential oils (EO), mouth rinse with essential oils and alcohol (EO+A), and mouth rinse with essential oils, alcohol, and hydrogen peroxide (EO+A+HP). Samples were bleached daily for 14 days with 10% carbamide peroxide gel for 4 hours and immersed in 5 mL of the assigned mouth rinse before and after bleaching. Surface microhardness (SMH), surface roughness (Ra), and color changes (ΔL*, Δa*, Δb*, ΔEab, and ΔE00) were assessed at baseline (T1) and post-treatment (T2). Data were analyzed using generalized linear mixed models and Kruskal–Wallis/Dunn tests. Results: All groups exhibited decreased SMH and increased Ra at T2. No significant differences in SMH were observed among groups, whereas Ra was highest in the EO+A+HP group. The EO+A and EO+A+HP groups showed greater Δa* and ΔE00 values compared with the control. Conclusion: Mouth rinses used during 10% carbamide peroxide bleaching increase roughness, reduce microhardness, and alter resin composite color, depending on their active ingredients.