Purpose: Argon lasers, because of their significant time savings over conventional curing lights and their ability to confer demineralization resistance on enamel, have been investigated for use in orthodontics. The purpose of this study was to assess their effect on the shear bond strength of brackets. Materials and Methods: Fifty intact human premolars were randomly divided in to 5 groups. In groups 1 and 2, the brackets were bonded with conventional light (600 mW) and argon laser (200 mW), respectively. In groups 3 and 4, the enamel was prelased, and then brackets were bonded as in groups 1 and 2, respectively. Brackets in group 5 were bonded conventionally, and after 2 days of immersion in artificial caries solution, laser was applied. Then all of the samples immersed in Ten Cate solution for 10 days. The shear bond strength was subsequently measured automatically using an Instron machine. One-way ANOVA, Dunnetts t-test and Tukeys test were used for data analysis. The adhesive remnants were also evaluated. Results: The mean shear bond strength of groups 2 and 5 were significantly lower than group 1 (p = 0.02, p = 0.01 respectively). There were no statistically significant differences between any laser treated groups (p > 0.05). The adhesive remnant index analysis revealed no statistically significant difference between all 5 groups (p > 0.05). Conclusion: Lasing the enamel before bracket bonding had no effect on bond strength. Laser application, during or after bracket bonding, may lead to lower bond strength.
Keywords: orthodontics, argon laser, composite curing system, bond strength