| Clinical treatment effect of the long-term stability depends on the alveolar bone remodeling.The osteoblasts and osteoclasts on the surface of alveolar bone involved in bone reconstruction and resorption and tooth movement after tooth is moved by the force. Maintained after the cessation of stress application, the changes of osteoblasts and osteoclasts is an important part of research on bone remodeling in the retention stage.Many experimental studies show that periodontal tissue in orthodontic tooth movement can be stimulated and produce a large amount of IGF-â… and OPG They can induce mesenchymal cell transformation and regulate differentiation and multiplication of the osteoclasts and osteoblasts. Fibroblasts and osteoblasts can produce IGF-â… and OPG also. However, the impacts of IGF-â… and OPG on periodontal tissue in retention stage have been reported rarely.Objective:This experiment is aimed at testing the change and pattern of osteoblasts and osteoclasts in periodontal tissues, and to discuss the impact of IGF-â… and OPG on teeth and surrounding tissues in retention stage.Methods:The experiment was carried out on thirty-six,8 weeks old female SD rats, weight 180-220g, and randomly divided into six groups, control group, to retention 1 day,4 days and 7 days,14 days and 21 days group, n=6. Space maintainence was done after applying force for 10 days. Histological changes in periodontium and expression of IGF-â… and OPG were observed on 1,4,7,14 and 21 days after tooth retention by using HE and immuno-histochemical staining. The results were analyzed by using SPSS13.0 software, using ANOVA, LSD and Pearson test. P<0.05 indicated significant or very significant difference respectively. Results:1. HE staining results:the periodontal fiber arrangement on the side of tension after 1 day retention was more disordered, and periodontal ligament was widened, and a significant formation of osteoblasts. Over time, the number of osteoblasts was reduced, and increased bone formation and gradual integration. In tension side of the 21-day group, periodontal ligament returned to the normal form.2. Normal periodontal tissue tension side of the IGF-â… and OPG showed a weak positive expression. The IGF-â… and OPG expression in the experimental group were highest of the 1 day retention group after 10 days of force. Fellow the time keeping, the two gradually decreased the expression of the 14-day retention group the 21 days retention group, OPG and maintain the expression of IGF-â… group and control group comparison ANOVA comparison, P> 0.05, no significant difference.3. IGF-â… and OPG Pearson correlation, N=108, r=0.81, indicating they are highly correlated.Conclusion:1. Phase of retention is not a dependent stadge, is the continuation, after the mobile extension of the completion of.2. It contins bone resorption on tension side of the phase of retention, and is complete at an earlier time, completed in 14 days, but bone formation completed at a later stage, continuing to 21 days.3. IGF-â… and OPG were standed in the bone remodeling,and IGF-â… and OPG are highly correlated;4. Retention after tooth movement in rats should be not less than 21 days.5. Orthodontic tooth movement requires a certain time to maintain. |
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