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

چکیده اصلی

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.

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