RESUMO
OBJECTIVE: The aim of this study was to evaluate, through a double-blind study, the effect of gallinium-aluminium- arsenic (GaAlAs) laser irradiation on the speed of orthodontic movement in canine premolars. METHODS: Eighteen dogs were divided into two groups, and their third molars were extracted. An orthodontic device was placed between the first molar and the second premolar for stabilization purpose. Group I was irradiated with a dosage of 5.25 J/cm(2) on the right side, whereas the left side was used as the control group. Group II was submitted to the same procedure, but was irradiated with a dosage of 35.0 J/cm(2). Irradiations were done every 7 days, for a total of nine irradiations. The orthodontic space was measured every 21 days. RESULTS: The 5.25 J/cm(2) dosage accelerated orthodontic movement during the first observation period, from 0 to 21 days (p < 0.05), whereas the 35.0 J/cm(2) dosage retarded the orthodontic movement in the treated group when compared with the control group, during both the first and second observation periods, from 0 to 42 days (p < 0.05). CONCLUSION: The results suggets that photoradiation may accelerate orthodontic movement at a dosage of 5.25 J/cm(2), whereas a higher dosage, 35.0 J/cm(2), may retard it.