[Effect of psoralen on the stability after orthodontic tooth movement in rats].

This study was designed to investigate the effect of psoralen on periodontal tissue reconstruction after orthodontic tooth movement(OTM) in rats. Thirty-six male 6-week-old Wistar rats were randomly divided into 2 groups: the experimental group and the control group. The experimental group and the control group were all installed between the central incisor and the left maxillary first molars to pull the first molars away from the force device; after 21 days, the force was removed and the rats in 2 groups were given drug gavage. Rats in the experimental group were given a gavage of psoralen 8 mg/kg per day, while rats in the control group were given the same amount of 0.9% sodium chloride everyday. Maxillary casts were made every week during the experimental and were scanned by 3D Scanner to measure relapse distance, and histologic examination was conducted. After 28 days, the rats were sacrificed and rats' upper jaw was separated. The remaining sections were immunohistochemically stained with BMP2 and BMP4. SPSS 19.0 software package was used for statistical analysis. RESULTS：Both groups had relapse after the force device was removed. Significant decrease of relapse percentage was observed in the experimental group compared with the control group at day 7，day 14，day 21 and day 28（P<0.05）. The speed of relapse of both groups were fastest in the first week and slowed down in the second, third and fourth week gradually. The speed of relapse in the experimental group in the first week was significantly less than in the control group(P<0.05).The expression of BMP2 and BMP4 within periodontal membrane and alveolar bone was significantly higher in the experimental group than in the control group(P<0.05). Psoralen can accelerate the reconstruction of periodontal tissues of orthodontic tooth and reduce relapse.