The effects of estrogen on experimental tooth movement in ovariectomized rats

Jin, Keun Ho; Kim, Jong Ghee; Park, Byung Keon; Kim, Oh Hwan

Abstract

The purpose of this study was to evaluate the effect of estrogen on the periodontium and alveolar bone tissue response during experimental tooth movement in ovariectomized rats. Eighty female rats, 250gm in body weight, were classified into four groups ; sham operated group(NN), ovariectomized group(ON), ovariectomized & estrogen injected group(OE), sham operated & estrogen injected injected group(NE), Rats were ovariectomized before 3 weeks to begin the experiment, which resulted in estrogen-deficient osteoporosis. In OE group & NE group, estrogen was injected 50microgramg/kg B.W. every other days. The left maxillary 1st molar was moved mesially with 60g force. Each four rats were sacrificed after 1, 3, 7, 15 days from application of orthodontic appliance and after additional 7 days from removal of orthodontic appliance. Histological findings on mesial roots of upper 1st molar in pressure and tension side are observed. The results were summarized as follows ; 1. In pressure side of alveolar bone, the number of osteoclasts and Howship's lacuna of ON group was significantly more than that of NN group from 1 day to 15 days(P<0.05). Especially the number of Howship's lacuna of ON group was significantly more than that of OE group during all experimental period(P<0.05). 2. In tension side of alveolar bone, the number of osteoclasts of ON group was significantly increased from 1 day to 3 days and decreased after 7 days. But the number of osteoclast of ON group was significantly more than that of NN group during all experimental period(P<0.05). Also the number of Howship's lacuna of all group was abruptly increased at 1 day, but slowly decreased till experimental 15 days. And the number of Howship's lacuna of ON group was significantly more than that of NN group from 0 hr to 7 days(P<0.05). 3. The speed of tooth movement of OE group & NE group was similar to that of NN group(P>0.05). The amount of tooth movement of ON group between 7 days and 15 days was significantly greater than those of other groups(P<0.05). 4. The degree of relapse of ON group after 7 days from removal of orthodontic appliance was similar to those of other group(P>0.05).