| Objective By constructing rat orthodontic tooth movement models under different force values,the morphological changes of the periodontal tissues and roots of the pressure side of the forceps were observed;the expression of HO-1,IL-10 and osteoclasts in the periodontium were detected.And changes in law;to explore the content of HO-1 and IL-10 in periodontal ligament and periodontal tissue remodeling,to further explore and elaborate the process of orthodontic tooth movement.Methods 32 male Wistar rats(aged 8-10 weeks)were randomly divided into 4 groups: 10 g group,20 g group,40 g group and 60 g group.The experimental groups(10g,20 g,40g,60g)were subjected to different forces to induce a mesially tipping movement of the right upper first molars with NiTi spring while left upper first molars were subjected to no treatment.The rats were sacrificed after 12 and 72 hours of orthodontic force application to simulate the occurring of OIIRR at different time points.The morphological alterations of periodontium on the pressure side of the orthodontic tooth were observed by HEstaining.The expression levels of HO-1 and IL-10 in periodontal ligament were determined by immunohistochemical analysis and were measured by Image-pro-plus6.0 image analysis system.The quantity of osteoclasts was examined by TRAP staining.Finally,all the data were analyzed by SPSS16.0statistical software.Results(1)successfully established rat orthodontic tooth movement models with different force values.(2)Under the light force,only the alveolar bone was absorbed on the pressure side of the force-applied tooth and no obvious root absorption was observed.In addition to the gravity,the alveolar bone was absorbed and the roots also showed different degrees of absorption.(3)The expression of HO-1 in the 12-hour experiment group was higher than that in the control group,and the difference was statistically significant(P<0.05).72 hours of HO-1 expression in the experimental groups and their own control group no difference(P> 0.05).(4)There was no significant difference in IL-12 between the experimental groups and the control group at 12 hours(P>0.05).The expression level in the10 g force group and 20 g force group at 72 h was higher than that in the control group.The expression level in the 60 g force group was lower than that in the control group,and the difference was statistically significant(P<0.05).(5)Compared with the 12-hour HO-1 experimental group,the expression level increased with the increase of the power value during the light force,reached the maximum value at the 40 g force value,and then no longer changed,the difference was statistically significant(P<0.05)..(6)Compared with the IL-10 experimental group of 72 hours,there was nochange in light force,and the expression level gradually decreased during gravity,and reached the lowest value when the force was 60 g.The difference was statistically significant(P<0.05).(7)There was a highly negative correlation between 12-hour HO-1 and 72-hour IL-10.(8)At 12 hours,there was no statistically significant difference in the number of osteoclasts between the experimental group and the control group(P<0.05);at72 hours,the number of osteoclasts in each of the forcing groups showed an increasing trend,compared with the control group.There was a statistically significant difference between the two groups(P<0.05).There was a statistically significant difference in the number of osteoclasts between the 10 g force group and the 40 g group and the 60 g force group(P<0.05).Conclusion HO-1 is present in the periodontal tissues of the rat occlusal pressure side and participates in the remodeling of the periodontal tissues during orthodontic tooth movement.The content of HO-1 increases with the increase of the force value.The 40 g force value does not change after reaching the maximum value. |
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