Effect of parathyroid hormone on experimental tooth movement in rats.

INTRODUCTION: The aim of this study was to investigate the effect of parathyroid hormone injection on experimental tooth movement in rats. METHODS: Sixty male Wistar rats were randomly divided into 2 groups. Their maxillary right first molars were moved mesially with nickel-titanium closed-coil springs. The experimental group received daily subcutaneous injections of parathyroid hormone at a dose of 4 mug per 100 g of body weight for 12 days, and the control group received vehicle injections. The results were evaluated by intraoral measurements and by hematoxylin and eosin, tartrate-resistant acid phosphatase, and immunohistochemistry staining. RESULTS: The tooth movement and osteoclast numbers were significantly increased in the parathyroid hormone group compared with the control group. The expressions of receptor activator of nuclear factor kappa B ligand and insulin-like growth factor-I were significantly stimulated in the parathyroid hormone group. CONCLUSIONS: The data suggest that short-term parathyroid hormone injection might be a potential method for accelerating orthodontic tooth movement by increasing the alveolar bone turnover rate.