comparison of shear bond strength, adhesive remnant index and enamel cracks in bonding and rebonding of stainless steel brackets to enamel surface conditioned with er:yag laser versus conventional acid etching

objectives: the aim of the present study was to compare shear bond strength (sbs), adhesive remnant index and enamel cracks in bonding and rebonding of brackets to enamel, conditioned with erbium-doped yttrium aluminium garnet (er:yag) laser and conventional acid-etching. materials and methods: fifty-two bovine lower incisors were randomly divided into four groups consisting of group 1 (acid-conditioning in both bondings), group 2 (acid-conditioning in first and laser-conditioning in second bonding), group 3 (laser-conditioning in first- and acid-conditioning in second bonding), and group 4 (laser-conditioning in both bondings). after bracket placement, the samples were thermocycled and tested for sbs in both bonding procedures. adhesive remnant index scores and enamel cracks were also determined. tukey s test and one-way analysis of variance was used for statistical analysis (p 0.05). results: mean sbs in the first bonding was 23.59mpa in groups 1 and 2, and 6.9mpa in groups 3 and 4. (p 0.001). the acid-etched teeth had a significantly lower sbs in rebonding, regardless of the reconditioning method (p 0.001). the sbs of the teeth conditioned with er:yag laser in the first bonding did not show significant changes in rebonding, although mean sbs was higher compared to the first bonding (p=0.675). bonding most often failed at the enamel-adhesive interface and enamel cracks were observed in a few teeth. conclusion: the method of primary enamel preparation can affect sbs in rebonding. based on our results, the mean sbs of er:yag-conditioned groups was clinically acceptable in bonding and rebonding, although it was lower compared to the acid-etched samples.