LLLT influences on periodontal tissue remodeling in rat tooth movement

Objectives: The purpose of this study was to investigate whether low level laser application influences on the periodontal tissue remodeling during orthodontic tooth movement in rats. via expression of OPG, RANK, RANKL, fibronectin and collagen type I in rat periodontium by immunohistochemistry. Methods: A total of 30 male sprague-dawley rats at 15 weeks old were divided into two groups of 15 rats each, to form the laser irradiation and non-irradiation groups. Total of 20 gm of force was applied to rat incisors to cause experimental tooth movement. The duration of tooth movement was 1, 3, 7, 14, 21 days. A Ga-Al-As diode laser was used to irradiate the area around the moved teeth for 10 seconds (8.3J/cm2) at each 6 points once a day for 7 days. Expression of OPG and RANKL were evaluated for bone remodeling, and proliferative activities of fibronectin and collagen type I for periodontal ligament change by immunohistochemistry. Furthermore, the expression of mRNA for IL-1b and TNFa were examined using semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR). Results: After the force application, laser irradiation group showed that the significantly strong expression of OPG and RANKL during total experimental period. Proliferative activities of fibronectin and collagen type I, however, were strongly expressed at early stages (1 and 3 days) in laser irradiation group. IL-1b mRNA expression was delayed and TNFa mRNA was down-regulated in laser irradiation group. Conclusion: These findings suggest that low-level laser application can stimulate periodontal tissue remodeling during experimental tooth movement in rats.