Does resin removal with different burs after orthodontic debonding influence hydrogen peroxide diffusion, bleaching efficacy, and enamel alterations during tooth bleaching? An in-vitro study

Abstract

Objectives

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.

Material and methods

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).

Results

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.

Conclusions

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.