| Research Abstract |
The purpose of the present study was to investigate the effect of transforming growth factor-β1 (TGF -β1), 1, 25-dihydroxyvitamine DィイD23ィエD2, 24, 25-dihydroxyvitamine D3 on relapse after experimental tooth movement in rats. Fifty five Sprague Dawley rats, 6 weeks old, were used for this experiment. The upper first molar was moved mesially with the magnitude of 20 gf exerted by a ringlet. It took about 48 days to obtain 1mm movement. The appliance them removed. 10ィイD1-10ィエD1〜10ィイD1-9ィエD1 mol/L 1, 25-dihydroxyvitamine DィイD23ィエD2, 10ィイD1-8ィエD1〜10ィイD1-5ィエD1 mol/L 24, 25-dihydroxyvitamine DィイD23ィエD2 or 0.2〜20ng/ml TGF -β1 was injected into the subperiosteum of upper first molar of animals of experimental groups every two days for 14 days. Injection was initiated on 2 days prior to removal of the appliance and continued till 12 days after the removal. 24, 25-dihydroxyvitamine DィイD23ィエD2 treated group, and TGF -β1 treated group showed suppressive effects on the relapse after experimental too
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th movement compared with PBS treated group. The PBS treated group exhibited 0.60 mm relapse on 12 days after removal of the appliance, while 10ィイD1-5ィエD1 mol/L 24, 25-dihydroxyvitamine DィイD23ィエD2 treated group showed 0.31 mm and 2 ng/ml TGF -β1 treated group showed 0.38 mm relapse, respectively. However, there was no significant difference between 1, 25-dihydroxyvitamine DィイD23ィエD2 treated group and PBS treated group.
Bone histomorphometrically, on the pressure side of the interradicular septum in 24, 25-dihydroxyvitamine DィイD23ィエD2 treated group and TGF -β1 treated group, BV/TV and Ob.S/BS were significantly larger, and Oc.S/BS and was No.Oc/BS were significantly smaller than those of PBS treated group on 12 days after removal of the appliance. On the tension side in 24, 25-dihydroxyvitamine DィイD23ィエD2 treated group and TGF-β1 treated group, BV/TV and Ob.S/BS were significantly large , and No.Oc/BS was significantly smaller than those of PBS treated group. There was no significant difference between 1, 25-dihydroxyvitamine DィイD23ィエD2 treated group and PBS treated group in BV/TV, Ob.S/BS, Oc.S/Bs, and No.Oc/BS on both pressure and tension sides.
These results suggest that the 24, 25-dihydroxyvitamine DィイD23ィエD2 and TGF -β1 inhibit bone resorption and stimulate bone formation of the alveolar bone during relapse after experimental tooth movement, and could be useful in preventing the orthodontic relapse. Less
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