Effects of laser therapy on the speed of orthodontic movement

Objectives: This study evaluated the effect of low level laser irradiation on the speed of orthodontic tooth movement of canines submitted to initial retraction. Methods: Twenty six canines were retracted using NiTi spring (force of 150g/side). Thirteen of those were irradiated with diode laser at the predetermined point areas in only one of the canines randomly chosen. Only one side of the arch was laser irradiated, representing the Laser Group (LG), while the other side was not irradiated and then considered Control Group (CG). The employed equipment was a semiconductor diode low level Alluminun-Gallium-arsenide (AsGaAl) laser that presents wavelength at the infra-red spectrum (ë=780nm) and emits continuous waves. The used output was 20mW, with energy density of 5J/cm2 and it was employed for 10 seconds per point, resulting in 0.2J of energy per point. As 10 points per tooth (5 bucally and 5 lingually) received irradiation, the total energy (TE) surrounding canine roots was 2J per treatment time. (780nm, 20mW, 10s, 5J/cm2) for 3 days; and the other 13 were not irradiated and thus considered control group. Patients were followed up for 4 months and 9 laser applications were performed (3 each month). The movement of canines was evaluated through 3D casts and the statistical analysis performed with ANOVA and Tukey test (P<0.05). Periapical x-rays of the studied teeth were submitted to Levander, Malmgreen and alveolar bone ridge analyses to evaluate tissue integrity and compared by Wilcoxon test (P<0.05). Results: A statistical significant increase on movement speed of irradiated canines was observed in comparison with no irradiated canines in all evaluation periods. No statistical significant difference was observed on bone and root resorption of canines irradiated or not. Conclusion: The diode laser used within the protocol guidelines increased the speed of tooth movement. This fact might reduce orthodontic treatment time.