Effects of traditional Chinese medicine pyritum on orthodontic tooth movement in rats.

INTRODUCTION

The objective of this study was to investigate the effects of pyritum on tooth movement.

METHODS

Thirty 9-week-old male Sprague Dawley rats were divided into 3 groups: control group, tooth movement + saline (TM+S) group, and tooth movement + pyritum (TM+P) group. The OTM model was established in both the TM+S group and the TM+P group. TM+P group received a local injection of pyritum decoction, whereas the other 2 groups received normal saline. Tooth movement distance was measured after 7 and 14 days. Histologic stains included hematoxylin and eosin staining for tissue morphology, tartrate-resistant acid phosphatase staining for osteoclasts, and immunohistochemistry for receptor activator of nuclear factor kappa β ligand (RANKL), osteoprotegerin (OPG), runt-related protein 2, and 5-bromo-2'-dexoyuridine.

RESULTS

At day 14, local injection of pyritum significantly (P <0.05) slowed down tooth movement, with the number of osteoclasts in the TM+P group significantly (P <0.05) reduced than that in the TM+S group. Runt-related protein 2 demonstrated higher expression in the TM+P group than in the TM+S group on both pressure and tension sides (P <0.05). The number of 5-bromo-2'-dexoyuridine-positive cells on the tension side in the TM+P group was significantly (P <0.05) higher than that in the TM+S group. RANKL expression on the pressure side in the TM+P group was significantly (P <0.05) lower than that in the TM+S group, whereas OPG expression exhibited an opposite trend. On days 7 and 14, the RANKL/OPG ratio in the TM+P group was significantly (P <0.05) lower than that in the TM+S group.

CONCLUSIONS

The study indicated that pyritum was capable of slowing down the speed of tooth movement while potentially promoting bone formation and inhibiting bone resorption.