The Expression Of HMGB1 In Periodontal Tissue During Experimental Tooth Movement In Rats

Objective: The aim of this investigation was to study the expression and distribution of HMGB1 in rat periodontal tissue under orthodontic force, this paper discusses the relationship between the HMGB1 and orthodontic tooth movement, to further un-derstand the mechanism of orthodontic moving and provide a theoretical basis for clinic of orthodontic treatment.Methods: 30 male wistar rats were randomly divided into five groups, with one blank group and four experimental groups, and each group with six rats .In each ex-perimental group, animal model was established as follow: the maxillary incisors of rats were selected as anchorage tooth, with 60g force to pull the first molar of the left maxillary to the mesial . Rats were killed respectively on 1, 3, 5, 7 days get the maxillary molars and surrounding tissues for HE dyeing and HMGB1 immuno-histochemical staining, histological observation and image analysis were carried out to testing the expression of HMGB1 in periodontal tissue in the mesial and distal of the first molar.Results: HMGB1 in periodontal tissue in the blank groups rats was in a strong stained, mainly express in the nucleus of fibroblasts, gum epithelial cells, bone cells and endothelial cell; On the first day, HMGB1 in periodontal tissues in tension area was not change obviously, periodontal membrane became narrow in pressure area and the HMGB1 decrease significantly. On the third day, periodontal cell hyperplasia ac-tively in the tension side, it seems that the expression of HMGB1 seems slightly in-creased, but the difference was not statistically significant. Periodontal membranes continue to become narrow in pressure area and the expression of HMGB1 remains weak. On the fifth day, cuboidal osteoblasts appear on the alveolar surface of tension zone, fibroblasts were stretched spindly, and HMGB1 still show a strong expression. A lot of osteoclast and bone resorption lacuna emerges on the pressure area, and HMGB1 expression increase slightly. On the seventh day, the thickness of new bone deposition increases, and there is no change in HMGB1 expression in tension area. In the pressure area, hyaline variable region become narrow, and the expression of HMGB1 increased.Conclusion: HMGB1 is exist in periodontal cells of normal rats and its distribu-tion is different according to the position, and its expression may be relevant to cell differentiation and state. Further experiments are needed to answer whether and how HMGB1 is participated in orthodontic tooth movement.