effect of argon laser on enamel demineralization around orthodontic brackets: an in vitro study.

this study was designed to evaluate the effect of argon laser irradiation on development and progress of enamel demineralization around orthodontic brackets.fifty caries-free, intact human premolars were randomly assigned to one of the following five equal groups: groups 1 (control) and 2: the brackets were bonded using conventional halogen light for 40s and argon laser for 10s, respectively. teeth in group 3 were lased with argon laser for 10s before bracket bonding with halogen light. group 4 was the same as group 3 except that brackets were also bonded with argon laser. in group 5 samples were bonded conventionally, immersed in an artificial caries solution for two days and then irradiated for 10s with argon laser. all samples were subjected to demineralization by artificial caries solution for 10 days. after bracket removal, samples were buccolingually sectioned and evaluated by polarized light microscopy. decalcified lesion depth in each section was measured by a trained examiner in a blind fashion. data were analyzed in spss 14 using one-way anova and tukey's hsd post hoc test.the control group showed the greatest mean lesion depth while group 5 revealed the lowest. the laser-treated groups had significantly lower mean lesion depth compared with the control group (p<0.05) except for group 4 (p=0.192).argon laser irradiation for 10s before or during bracket bonding can increase caries resistance of intact and demineralized enamel.