Influence of Propolis Extract on Bleaching Effectiveness and Enamel Physical Properties

This study evaluated the effects of propolis extract on dental enamel following tooth bleaching with 35% hydrogen peroxide (HP).

Sixty bovine enamel specimens were divided into six groups: Artificial Saliva (Control); Whiteness HP35% (HP35%); Whiteness HP35% + potassium nitrate desensitizer (HP35%+KF); Whiteness HP35% + potassium nitrate desensitizer + propolis extract (HP35%+KF+P); Whiteness HP35% + neutral fluoride + propolis extract (HP35%+F+P); and Whiteness HP35% + propolis extract (HP35%+P). The in-office bleaching protocol consisted of three sessions (3 × 15 minutes). Color change (ΔE*, ΔE₀₀, ΔWID), surface roughness (Ra), and microhardness (KHN) were evaluated at baseline (T₁) and after 24 hours (T₂). Color parameters were analyzed using generalized linear models (p ≤ 0.05), and Ra and KHN were assessed using a generalized linear mixed model for repeated measures (p ≤ 0.05).

All HP-treated groups showed significantly greater color change compared to the control group. Surface roughness increased after bleaching; however, groups treated with desensitizers, fluoride, and/or propolis showed lower Ra values at T₂ compared to baseline. For microhardness, only the HP35%+KF+P group maintained KHN values comparable to the control group after bleaching.

Propolis extract did not compromise the whitening efficacy or negatively affect enamel surface roughness or microhardness following treatment with high-concentration hydrogen peroxide.