effect of four methods of surface treatment on shear bond strength of orthodontic brackets to zirconium

o bjectives: providing reliable attachment between bracket base and zirconia surface is a prerequisite for exertion of orthodontic force. the purpose of the present study was to eval- uate the effect of four zirconium surface treatment methods on shear bond strength (sbs) of orthodontic brackets. mat erials and methods: one block of zirconium was trimmed into four zirconium sur- faces, which served as our four study groups and each had 18 metal brackets bonded to them. once the glazed layer was removed, the first group was etched with 9.6% hydrofluoric acid (hf), and the other three groups were prepared by means of sandblasting and 1 w, and 2 w er: yag laser, respectively. after application of silane, central incisor brackets were bonded to the zirconium surfaces. the sbs values were measured by a dartec testing ma- chine with a crosshead speed of 1 mm/min. results: the highest sbs was achieved in the sandblasted group (7.81±1.02 mpa) followed in a descending order by 2 w laser group (6.95±0.87 mpa), 1 w laser group (6.87±0.92mpa) and hf acid etched group (5.84±0.78 mpa). the differences between the study groups, were statistically significant except between the laser groups (p < 0.05). conclusion: in terms of higher bond strength and safety, sandblasting and er: yag laser irradiation with power output of 1 w and 2 w can be considered more appropriate alterna- tives to hf acid etching for zirconium surface treatment prior to bracket bonding.