Effect of Simvastatin and Low-Level Laser Therapy on Sutural Bone Formation After Expansion in Rats: Biomechanical, Computed Tomography and Immunohistochemical Assessment.

Introduction: The application of low-level laser therapy (LLLT) and some medications have been shown to accelerate bone formation in rapid palatal expansion (RPE). A combination of these two therapeutic modalities may reduce the time required for the retention period. This study sought to assess the effects of simvastatin and LLLT, alone and combined, on sutural bone formation in rats. Methods: Sixty male Wistar rats averagely weighing 150 g were divided into five groups (n=12) of control (group 1), 5 mg simvastatin (group 2), 10 mg simvastatin (group 3), LLLT (group 4), and LLLT plus 10 mg simvastatin (group 5). The expansion appliance was placed in the parietal bone in all groups. One week after placing the appliance, the spring was fixed with Duralay acrylic resin to serve as a retainer during the rest of the experiment. The rats were sacrificed after 30 (for biomechanical and computed tomography [CT] assessments) or 60 days (for biomechanical, CT and immunohistochemical [IHC] assessments). Results: Groups 3 and 4 showed a significant improvement in osteogenesis (confirmed by CT findings, histological analysis and biomechanical test) compared to the control group. Group 5 was significantly superior to all other groups in terms of all parameters ( P  < 0.001). Group 2 and the control group were not significantly different ( P >0.05). Conclusion: Although LLLT, simvastatin treatment and the combination of both significantly improved sutural bone formation in rats compared to the control group, the combined treatment showed significantly superior clinical results compared to other interventions.