A Study On The Effect Of Modified Functional Twin-block On Condylar In Growing Rabbits

Objective The study was to establish the animal model of mandibular protrusion and analyze the adaptive remodeling of condyle,through releasing the stress of temporomandibular joint.Investigate the effect of modified functional twin-block appliance on extracellular matrix and proliferation in the different parts of condylar cartilage as well as subchondral bone.Methods1.Eighteen rabbits with eight weeks of age were simple randomly divided into three groups.In the functional group,The modified functional appliance consist of double teeth pad in the rabbits’ upper and lower molars,at the same time,exert vertical elastic force in anterior teeth to release the stress of TMJ。2.Examed the morphological change by HE staining3.The expression of growth factors such as VEGF、SOX-9、collagen Ⅱ in condylar were evaluated by immunohistochemistry.4.To evaluate the architecture and the measurement of bone histomorphometry.Result1.The thickness of condylar cartilage in the modified functional twin-block appliance group increased most in the experiment.2.In the group of control and experimental,the growth factors expression were the most in the middle and posterior region of the condyle.In the anterior of condyle,the VEGF expression in modified functional twin-block appliance group is higher than others.3.In the modified twin-block appliance group,The amont of bone volume fraction and trabecular thickness were the largest,compared with the control group.However,the number of trabecular bone is less than others.Conclusion The growth factors expression is elevated during use the modified functional twin-block appliance.In this study,the thickness of condylar cartilage,experssion of growth factors and remodeling of subchondral bone has a high correlation with the adaptive remodeling of the condyle after functional appliance.