Effect of CO₂ laser irradiation on shear bond strength and enamel surface roughness after ceramic brackets removal:...

This study aimed to evaluate the shear bond strength and surface roughness of the enamel after removal of ceramic brackets with CO₂ laser. Thirty extracted premolars were randomly assigned to three groups (n = 10): Untreated enamel (GI), Conventional debonding (GII), and CO₂ laser debonding (GIII). Polycrystalline ceramic brackets were adhered on the buccal surface of GII and GIII groups, using 35% phosphoric acid and Transbond Plus Color Change resin (3 M Unitek; Monrovia, California, USA); shear bond strength was evaluated with a universal testing machine (EZ Graph; Shimadzu, Kyoto, Japan). Prior to debonding, brackets in the GIII group were irradiated with a CO₂ laser (Yoshida Dental MFG; Tokyo, Japan) at a wavelength of 10.6 μm, power output of 6 W, for 5 s, at 5 mm. Each specimen was evaluated for adhesive remnant index score, and enamel surfaces were polished to assess roughness (with and without the CO₂ laser) under atomic force microscopy. Ra, Rq, and Ry roughness parameters were analyzed. Statistical analysis was carried out using Student's t-test to evaluate shear bond strength, the Mann-Whitney U to assess the adhesive remnant index, and the Kruskal-Wallis and Dunn's post hoc to examine enamel roughness. GIII group showed statistically significant differences, with a reduction in shear bond strength (p < 0.001) and enamel roughness (p < 0.0083) compared to GII. These findings indicate that CO₂ laser irradiation can be considered as an alternative in debonding ceramic brackets in orthodontic treatments.