Bone resorption and natural turnover of ligature-induced periodontitis in rats

AIM:To observe the bone resorption in rats with ligature-induced periodontitis and the natural turnover after removing the ligation.METHODS:32 adult male SD rats were randomly divided into 4 groups(n = 8). The right maxillary first molar was assigned to receive wire ligation in the sulcular position,while the contralateral tooth was unligated as the control.The molars in group A were ligated for 7 day;in group B for 21 day;in group C were ligated for 21-days,then the ligation was removed and the rats were fed for another 7 days;in group D were ligated for 21-days,then the ligation was removed and the rats were fed for another 21 days.At the end of the treatment.the animals were sacrificed and the periodontal tissue of the teeth were examined by micro-CT,HE and tartrate resistant acid-phosphatase(TRAP) staining.RESULTS:Inflammatory infiltration in the gingival tissue,osteoclasts lining on the alveolar bone,and decreased alveolar bone height were observed in group A and B.The decrease of bone mineral density(BMD) under the furcation of group B was significant(P 0.05).In groups C and D,the inflammation degree were reduced,the number of osteoclasts decreased,and the alveolar bone height increased when compared with those in group B.BMD of group D was significantly higher than that of group B(P 0.05).CONCLUSION:In the ligature-induced periodontitis of rat model,ligation can promote the development of periodontitis,while removal of the ligation can prevent the development of periodontitis,and activate the self-repair of periodontal tissues.