Expression Of SHP-2in Periodontal Tissue During Orthodontic Tooth Movement In Rats

Aim： To explore the expression of SHP-2in periodontal tissue duringexperimental orthodontic tooth movement in rats, and study the function of SHP-2on orthodontic tooth movement.Method：64male Wistar rats（8weeks old, weights200±10g） were dividedinto8groups randomly, each group had8rats. Tooth movement time points set as0,1,3,5,7,10,14and21d. The right maxillary side was used as the experimentalgroup（EG） and the left maxillary side as the control group（CG） to establishorthodontic tooth movement model. By using closed nickel-titanium coil springs, a50g force was applied between the upper incisors and the maxillary right first molarsin order to mimic orthodontic biomechanics. These forces were kept constant for theset time and followed by animal sacrifice. First, take the plaster model of the tissue,and measure the move distance of the first molar in the plaster model. Then,2piecesof tissues in each group (each group contains8pieces of tissues) were selectedrandomly. Capture the radiographs of the first molar distal roots by scanning electronmicroscope, and observe the root resorption of the mesial surface of distal roots.Next,6pieces of the periodontal tissues in each group were conducted byhematoxylin-eosin staining and immunohistochemistry analysis. The expression ofSHP-2on the tensional and compressive sides were measured by the average opticaldensity. Moreover, compare the expression trend of SHP-2with BMP-2(a key factorin the differentiation of osteoblasts) and TNF-α (a key factor in the differentiationof osteoclasts). Finally, the outcomes were analyzed using SPSS.Result:1、The mesial movement of the first molars were obvious. The root resorptionwas observed in the mesial surface of distal roots. 2、The expression of SHP-2on both the tension and the pressure sides in EGwere increased initially, and then decreased during the period of experimentalorthodontic tooth movement. The expression of SHP-2on both the tensional andcompressive sides in EG reached the peak on3day, then were almost equal to theCG on21day. The expression of SHP-2in CG was steadily weak. The expression ofSHP-2on the tensional side was higher than the compressive side, statisticallysignificant differences were observed on1、5、7day.3、Both the expression of BMP-2on the tensional side and TNF-α on thecompressive side in EG were increased initially, and then decreased during theperiod of experimental orthodontic tooth movement. The expression trend of SHP-2on the tensional side were similar compared to the expression of BMP-2on thetensional side. The expression trend of SHP-2on the compressive side were similarcompared to the expression of TNF-α on the compressive side.Conclusion：The expression of SHP-2in periodontal tissue during orthodontictooth movement in rats reflects that SHP-2involved in the process of alveolar boneremodeling. SHP-2is a crucial factor in the differentiation of osteoblasts andosteoclasts, playing an important role in orthodontic tooth movement.