Abstract

Introduction: Several experimental studies have displayed positive result for laser radiation on stimulating bone regeneration in recent years. The purpose of this experimental study was to determine low-level laser (LLL) effects on partial bone defects in hypothyroidism male rat. Methods: Forty male Wistar rats were randomly distributed as below groups: hypothyroidism + laser (Hypo + laser), hypothyroidism (Hypo), and control. Four weeks after surgery, the tibia bone was removed. Biomechanical and histological examinations were performed immediately. Results: Our results showed significant reduction in the absorption of energy, resistance in bending deformation (bending stiffness), maximum force, high stress load, trabecular bone volume, and number of osteocytes, osteoblasts and osteoclasts in the osteotomy site in hypothyroidism rats compared to hypothyroidism + laser group (P < 0.05). Conclusion: The results indicated that using laser may improve fracture regeneration and it may accelerate bone healing in hypothyroidism rat.