This study aimed to identify the optimal technological parameters for rebonding zirconia brackets treated using an erbium-doped yttrium aluminum garnet (Er:YAG) laser. Er:YAG lasers with varying energies were compared with the flaming and sandblasting treatment methods. Detached zirconia brackets were treated and evaluated for shear rebond strength, bracket bottom-plate morphology, position, and depth of microleakage. They were then treated for rebonding using flaming, sandblasting, or an Er:YAG laser set at 250-mJ, 300-mJ, 350-mJ energy. Their shear rebond strength were measured using microforce tester. The topography of the treated bottom plates were observed using scanning electron microscopy. A confocal laser scanning microscope was used to measure the depth of the joint and gingival-side microleakage at the bracket-adhesive (B-A) and enamel-adhesive interfaces. With 300 mJ Er:YAG laser treatment, the detached zirconia brackets can obtain good rebonding strength and minimize the shape change of bracket bottom plates; the adhesion of the B-A interface is better than other methods.
Keywords: Er:YAG laser; Microleakage; Shear rebonding strength; Zirconia bracket.