Abstract
The aim of this article was to determine whether mechanical forces combined with LLLT stimulate expression of OPG, RANKL, and RANK in animal model by immunohistochemistry. A total of 20 sprague-dawley rats at 15 weeks old were divided into two groups of 10 rats each, to form the laser irradiation and nonirradiation groups. Total of 20 mg of orthodontic force was applied to rat incisors. The duration of tooth movement was 1, 3, 7, 14, and 21 days. A Ga-Al-As diode laser was used to irradiate the area around the moved teeth for 10 seconds once a day for 7 days. Proliferative activities of OPG, RANKL, and RANK were evaluated immunohistochemically. After the application of force, the induction of OPG, RANKL, and RANK was observed on both groups. In the laser irradiation group, however, the expression of OPG, RANKL, and RANK was significantly greater than that of the nonirradiation group at day 1 to day 21. This is the first study about immunohistological findings of RANK/RANKL/OPG triad under LLLT during tooth movement. These findings suggest that low level laser therapy can stimulate bone turnover during experimental orthodontic tooth movement.