Comparative evaluation of shear bond strength of metallic orthodontic brackets bonded to enamel prepared with Laser etching and conventional etching after bleaching: An in vitro study.

Abstract

Objectives: Comparing effect of Er:YAG (Erbium:Yttrium–Aluminum–Garnet) laser versus typical phosphoric acid etching on the shear bond strength of orthodontic brackets after office bleaching.Materials & Methods: Eighty freshly extracted premolars were randomly divided into four groups (n=20) as follows; Group I: conventional acid etching, Group II: Er:YAG laser etching. Group III: bleaching followed by conventional etching, while Group IV: bleaching followed by laser etching. The brackets were bonded to the enamel surfaces, and Shear Bond Strength (SBS) was measured using a universal testing machine. Adhesive remnant index (ARI) scores were determined after debonding under a stereomicroscope. Statistical analysis was performed using the t-test and ANOVA, with significance set at p < 0.05.Results: The bleaching/laser etching group exhibited significantly higher SBS (mean 18.08 MPa) compared to the bleaching/acid etching group (mean 4.15 MPa), indicating superior bonding performance with laser etching. No significant difference was observed between the laser etching group (mean 16.13 MPa) and the conventional etching group (mean 18.54 MPa).Conclusion: Laser conditioning significantly improves SBS in orthodontic brackets applied after bleaching compared to conventional acid etching. Both laser and conventional etching are effective methods, but laser conditioning offers additional benefits for bonding post-bleaching.