The effects of diode laser (660 nm) on the rate of tooth movements: an animal study

Low-level laser has been indicated to have the capability to facilitate the differentiation of the osteoclastic and osteoblastic cells which are responsible for the bone remodeling process. The aim of this study was to evaluate the effects of InGaAlP laser with a wavelength of 660 nm on the rate of tooth movement and histological status. Thirty male Wistar rats of 7 weeks old were selected for this study. The rats were randomly divided into two groups of 15 each to form the experimental (laser-irradiated) and control (non-irradiated) groups. The control group received unilateral orthodontic appliance design (one quadrant), but the laser-irradiated group received split-mouth design, with orthodontic appliance on both sides and laser irradiation on one side only (group b) and on the contralateral side (group c). The orthodontic appliance consisted of a NiTi closed coil spring with a length of 5 mm which was ligated to maxillary molar and incisor. A total of 60 g of force was applied to the rat molar. The diode laser (660 nm) was irradiated with an output power of 25 mW in continuous mode for a total time of 5 min in the laser-irradiated group. After 14 days of orthodontic tooth movement, the amount of tooth movements was measured. In the laser-irradiated group, the amount of tooth movement was significantly greater than that of the non-irradiated group (2.3-fold), but there was no significant difference between the non-irradiated and indirectly irradiated groups. Histopathological studies revealed that the number of osteoclasts in the laser-irradiated group was significantly greater than that of the non-irradiated group (1.5-fold) while this number was almost the same in the non-irradiated and indirectly irradiated groups. The results suggested that low-level laser can accelerate the rate of bone remodeling. However, in order to utilize the low-level laser as an adjunct in orthodontic practice on patients, further research studies are needed for finding the appropriate dosage for the human tissues.