Variation Of MMP-8 Expression In Periodontal Tissues In Rats With Periodontitis During Orthodontic Tooth Movement

Objective: To study the normal and inflammation of periodontal tissue remodeling in rats underwent orthodontic force,and the expression and distribution of matrix metalloproteinase-8(MMP-8).To explore the effect of inflammatory periodontal environment and orthodontic forces on periodontal tissue remodeling in rats.Methods: 50 healthy male wistar rats(weight 200-250 g)were randomly divided into 2 groups,including normal force group 25(control group),inflammatory force group 25(experimental group).After establishing experimental periodontitis model for 4 weeks,the periodontal irritants were removed and 50 g orthodontic forces were applied respectively to the maxillary first molars.5 rats were sacrificed on the 1st,3rd,5th,7th,and 14 th day after the strength.The tooth movement distance was measured.Meanwhile,the periodontal tissue morphology was observed by HE staining,and the expression of MMP-8 in the pressure side and tension side periodontium tissues was detected by IHC.Results: 1 Distance of tooth movement: the distance of tooth movement in the experimental group,compared with the control group were significantly grater,with statistical significant on 3,5,7 and 14 days(P<0.05).2 Histological results: from the point of the variation for the periodontal ligament(PDL)on the pressure side,the tension side,and the bone resorption pits on the alveolar bone(Ab)surface,two groups has not any significant difference.However,the number of osteoclasts in the experimental groups increased significantly.3 IHC results: the expression intensity of MMP-8 in the experimental group was higher than that in the control group,both of which showed a trend of increasing firstly and then decreasing,and peaked at the 5th day.There was a significant difference between the 3rd,5th,7th,and 14 th days(P<0.05).At the same time point,the expression intensity of MMP-8 on the pressure side for the two groups was higher than that of the tension side with the statistical difference on 1,3,5,7 and 14 days(P<0.05).Conclusions:1 After the orthodontic force of periodontitis in rats,the movement speed of teeth was faster than that of normal teeth movement,and the periodontal tissue injury was relatively increased.2 Under the effect of orthodontic force,the expression of MMP-8 in Inflammatory periodontal tissue was increased and the pressure side was more obvious.The declined expression occur with the reduced orthodontic force with the passage of time,which indicates that MMP-8 was involved in the tooth reconstruction process under the action of mechanical force,especially for the pressure side.