Influence of Propolis Extract on Bleaching Effectiveness and Enamel Physical Properties.

Abstract

<h4>Objectives</h4>This study evaluated the effects of propolis extract on dental enamel following tooth bleaching with 35% hydrogen peroxide (HP).<h4>Materials and methods</h4>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).<h4>Results</h4>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.<h4>Conclusion</h4>Propolis extract did not compromise the whitening efficacy or negatively affect enamel surface roughness or microhardness following treatment with high-concentration hydrogen peroxide.