Effect of chitosan-containing desensitizers applied prior to bleaching on the physical properties of enamel.

This in vitro study evaluated the effects of adding chitosan (Chi) to desensitizing agents applied before dental bleaching on enamel properties. Bovine enamel specimens were allocated to seven groups (n = 12): no treatment (negative control), 2% NaF (positive control), 2% NaF + 2% Chi, 2% NaF + 5% Chi, 2% NaF + 5% KNO3, 2% NaF + 5% KNO3 + 2% Chi, and 2% NaF + 5% KNO3 + 5% Chi. All specimens underwent three bleaching sessions with 35% hydrogen peroxide, each preceded by a 10-min application of desensitizing agents. Color change (∆L*, ∆a*, ∆b*, ∆Eab, and ∆E00), whiteness index (∆WID), surface roughness (Ra), and microhardness (SMH) were evaluated at baseline (T0) and after each session (T1-T3). Scanning electron microscopy analysis was performed at T3. Color parameters did not differ among groups (p > 0.05), indicating bleaching efficacy. Surface roughness increased in all groups (p < 0.0001), with greater increases in chitosan-containing groups. However, groups 2% NaF + 5% Chi and 2% NaF + 5% KNO3 + 5% Chi showed significantly higher microhardness values than controls at T2 and T3. Incorporation of chitosan into desensitizing agents increased enamel surface roughness but preserved microhardness without compromising bleaching efficacy. These findings suggest chitosan may represent strategy for protecting enamel during in-office bleaching.