Changes In The Content Of TGF-β₁ In Root Resorption Caused By Depressing The Molars Of Beagle Dogs

Objective:To investigate the role of TGF-β₁ in orthodontic root resorption.Through the establishment of an experimental animal model of orthodontic force-induced root resorption,the expression and content of TGF-β₁ in healthy beagles and root resorption beagles were observed.Methods:Five adult male beagles with a body weight of10kg±2kg were randomly divided into experimental group（3）and control group（2）.A microimplant was inserted into the buccal and palatine sides of the first maxillary molar of the beagles as anchors.The experimental group was immediately applied 150g constant suppressing force with a chain rubber band.In the control group,no force was applied.The venous blood of the subcutaneous head on the inner side of the forelimb of beagles was collected at different afterstress durations（0days,6weeks,9weeks and 12weeks）during the experiment period.The first and second molars of the beagle were removed completely after 12 weeks of continuous exertion.Observe the histological changes in the root peripheries of the maxillary first molars of Beagle dogs after HE staining.The changes of TGF-β₁ content in serum of beagle dogs under different stress durations were detected by ELISA.The differences of TGF-β₁ content in peri-root tissues of maxillary first and second molars between the two groups were detected by WB.Use SPSS 23.0data analysis software for data processing.Results:Absorption pits of cementum were found in the root tip area of depressed molars in the pressure group,and a lot of tooth-breaking cells and macrophages can be seen in the pit.Simultaneously,osteoblasts,osteoblasts and fibroblasts were also observed to repair and remodel root resorption.The serum concentration of TGF-β₁ in the experimental group increased gradually with the prolongation of the depression duration（P<0.05）,and the concentration of TGF-β₁ in the serum of Beagle dogs at the 12th week after stress was significantly higher than that on the 0th day,while the fluctuation was not significant in the control group（P>0.05）.At the 9th and 12th week of the experiment,the serum TGF-β₁ concentration of the experimental group was significantly higher than that of the control group（P<0.05）.WB detection showed that at 12 weeks of the experiment,the content of TGF-β₁ in the periodontal tissue of the depressed molars in the experimental group was significantly higher than that in the control group and the adjacent control group.Conclusion:The pressure value of 150g can effectively suppress the maxillary molars of beagle dogs,and the bone resorption occurs with the repair and reconstruction of peri-root tissue.The change of TGF-β₁ content in local tissue was consistent with that in peripheral blood.The concentration of TGF-β₁ increased with the onset and progression of the root resorption in beagle canines,which confirmed that TGF-β₁ is related to orthodontic root resorption,and speculated that TGF-β₁ factor plays a certain role in the repair and reconstruction of root resorption.