To evaluate the influence of different burs for residual resin removal after orthodontic debonding on hydrogen peroxide (H ₂ O ₂ ) concentration into the pulp chamber, bleaching efficacy and physical changes on the enamel surface following in-office tooth bleaching.

Sixty premolars subjected to bracket installation and debonding were randomized into five groups ( n = 12): no bleaching (control), only bleaching, Carbide bur + bleaching (CB), Diamond FF bur + bleaching (DB) and Zirconia bur + bleaching (ZB). All groups, except the control, received bleaching (H ₂ O ₂ 35%). The H ₂ O ₂ concentration (μg/mL) in the pulp chamber was measured using a UV-Vis spectrophotometer. Bleaching efficacy was assessed by a digital spectrophotometer (ΔE _ab , ΔE ₀₀ , and WI _D ) before and after 7 days of bleaching. Enamel surface alterations were analysed by FE-SEM. All data were submitted to statistical analysis (α = 0.05).

The groups submitted to resin removal with CB and ZB post-orthodontic debonding showed a lower H ₂ O ₂ concentration when compared to the Only Bleaching group after bleaching procedure ( P < 0.02). No significant differences were observed in bleaching efficacy between groups submitted to different burs when compared to the Only bleaching group ( P > 0.05) across evaluated parameters.

The use of CB and ZB burs to remove residual resin post-orthodontic debonding results in lower H ₂ O ₂ concentration. However, bleaching efficacy was unaffected by bur type. Notably, ZB burs provided superior enamel surface preservation.