Differential Energy Laser Regulates Orthodontic Tooth Movement And Bone Remodeling

This study investigates the effects of low-level and high-level laser on orthodontic tooth movement (OTM) in rats, aiming to determine optimal parameters and assess bone remodeling. Self-controlled groups of 6-week-old SD rats were used, with 650-nm diode laser regulating OTM acceleration and inhibition. Five subgroups with different energy densities were created by varying laser irradiation duration every other day. Rats were sacrificed on days 7, 14, and 21. Micro-CT measured OTM distance to select the best parameter groups. HE and TRAP staining observed periodontal tissue and osteoclasts, while real-time PCR and immunohistochemistry analyzed gene and protein expression. Energy densities of 6.7 J/cm² and 106.7 J/cm² were optimal for accelerating and inhibiting OTM, with efficiencies of 34.9% and 36.7%, respectively. On days 7 and 14, the 6.7 J/cm² subgroup had increased lacunae and osteoclasts, while the 106.7 J/cm² subgroup had decreased levels. Gene expression showed upregulation of RANKL, ALP, RUNX2, and OCN, and downregulation of OPG in the 6.7 J/cm² subgroup, with opposite results in the 106.7 J/cm² subgroup. The study concludes that diode laser with different energy densities can regulate OTM. Laser irradiation at 6.7 J/cm² accelerated OTM by 34.9%, while 106.7 J/cm² decreased OTM by 36.7%. This corresponded with changes in osteoclast and osteoblast activity in the surrounding bone.