Bone Formation-promoting Effect of Daidzein after Experimental Tooth Movement in Middle-aged Female Model Rats

This study focused on Daidzein（DZ）. The aim was to promote bone formation and suppress relapse by administering DZ after tooth movement in a middle-aged female orthodontic patient model rat. Using female Wistar rats（n=36）, we performed an ovariectomy（OVX）at 60 days of age and started the experiment at 88 days of age. The rats were randomly divided into two groups: the DZ group, which received DZ administration during the retention period, and the Control group. The right first maxillary molar was moved over a 14-day period, followed by a 14-day retention using composite resin（CR）. After retention, the CR was removed, and a 14-day relapse observation was conducted. bone structure analysis, including bone density and bone volume fraction, was performed using micro-CT to measure tooth movement and relapse amount. Immunohistochemical staining was also conducted using BMP-2, Runx-2, and Osx, which are bone formation markers. The relapse rate was significantly lower in the DZ group compared to the Control group. Bone density and bone volume fraction were significantly increased in the DZ group on days 28 and 42 compared to the Control group. Immunohistochemical staining showed a significant increase in bone formation factors Runx-2, BMP-2, and Osx in the DZ group on days 28 and 42. The results of administering DZ during the retention period in a middle-aged female orthodontic patient model rat suggest the possibility of reducing the risk of relapse in middle-aged female orthodontic patients.