Does resin removal with different burs after orthodontic debonding influence hydrogen peroxide diffusion, bleaching...

To evaluate the influence of different burs for residual resin removal after orthodontic debonding on hydrogen peroxide (H₂O₂) 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 (H₂O₂ 35%). The H₂O₂ concentration (μg/mL) in the pulp chamber was measured using a UV-Vis spectrophotometer. Bleaching efficacy was assessed by a digital spectrophotometer (ΔE_ab, ΔE₀₀, 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 H₂O₂ 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 H₂O₂ concentration. However, bleaching efficacy was unaffected by bur type. Notably, ZB burs provided superior enamel surface preservation.