Editor's Comment and Q&A : Effects of simvastatin on relapse and remodeling of periodontal tissues after tooth movement in rats

Introduction Our objectives were to determine the effects of simvastatin on relapse and periodontal tissue remodeling after experimental tooth movement in rats and to explore the molecule mechanism. Methods Thirty-two adult male Wistar rats were randomly divided into 2 groups. Bilateral mandibular first molars were moved mesially with nickel-titanium closed-coil springs in both groups. On the 21st day, the springs were removed, and dental casts were made. Animals in the experimental group began receiving simvastatin at a dose of 2.5 mg per kilogram per day for 4 weeks, and animals in the control group received 0.9% sodium chloride. The results were evaluated by model measuring and immunohistochemistry staining. Results Relapse distances and relapse percentages were decreased in the simvastatin group compared with the controls. Osteoprotegerin expression increased, and RANKL decreased. Conclusions These results indicate that simvastatin inhibits the bone-resorbing activity of osteoclasts while stimulating bone formation, probably by controlling the ratio of local osteoprotegerin to RANKL in the periodontal tissues. Therefore, it might be useful for retention.