Influence of commercial mouth rinses with different formulations on enamel properties during at-home bleaching

Dental bleaching is a widely used esthetic procedure often associated with oral hygiene products such as mouth rinses. However, the effects of different mouth rinse formulations on enamel during bleaching remain unclear. This study evaluated in vitro the properties of dental enamel exposed to mouth rinses with different active ingredients during at-home bleaching with 10% carbamide peroxide. Bovine enamel-dentin discs were randomly assigned to four groups (n=12): distilled water (DW, control), Listerine Cool Mint Zero Alcohol (CMZ, essential oils), Listerine Cool Mint (CM, essential oils + alcohol), and Listerine Whitening Extreme (WE, essential oils + alcohol + hydrogen peroxide). Bleaching was performed for 4 h/day for 14 days, and mouth rinses were applied twice daily. Color parameters (ΔL* ,Δa*, Δb*, ΔE, ΔE), surface roughness (Ra), and microhardness (KHN) were evaluated at baseline and after treatment. Surface morphology was analyzed by scanning electron microscopy (SEM). Data were analyzed using linear mixed models, generalized linear mixed models, and Kruskal-Wallis tests (α=0.05). No significant differences among groups were observed for color change or surface roughness (p›0.05). All groups showed a significant reduction in microhardness over time (p‹0.05). CMZ and CM exhibited the greatest decrease in microhardness at the final evaluation, differing significantly from the other groups (p‹0.05). SEM images revealed similar surface alterations in all groups, including porosity and depressions. Mouth rinses did not affect bleaching effi cacy or enamel color. Although enamel microhardness, roughness, and morphology changed after bleaching, only microhardness and morphological alterations were influenced by the active ingredients of the mouth rinses. CLINICAL RELEVANCE: The use of mouth rinses during at-home bleaching with carbamide peroxide does not compromise the bleaching efficacy. However, it may adversely affect the properties of dental enamel.