Study Of The Effect Of Mandibular Distraction Osteogenesis On The Tissue Remodeling And The Change Of The Extracelluar Matrix Of Canine Condyle

As a new therapy method that was introduced by Codivilla from Italy in 1905,distraction osteogenesis (DO) had been undergoing a long way to thrive. The research on this area has not been stopped yet. The conclusions of studies from abroad on the effect of mandibular distraction osteogenesis on TMJ showed great differences, and rare relative study was seen by now inland.In this study, fourteen young canines with the age of four to six months old were adopted to establish models of bilateral mandibular distraction osteogenesis. Then the effect of mandibular distraction osteogenesis on the extracelluar matrix of canine condyle was studied with these models by means of scanning electron microscope, immunohistochemical and histochemical methods. This study was a further research on the response of TMJ during DO, and it may offer the experimental basis for the clinical therapy.The study consists of three parts:1 .Ultrastructure changes of condyle following mandibular distraction osteogenesisResults: The agglutinating substances of the condyle decreased and became irregular soon after DO. The surface of condyle was partly destroyed; the underlying collagen fibers were loosed, or even worse disordered and exposed. 8 weeks later, the surface of condyle resumed and looked like the normal structure.Conclusion: Mandibular distraction osteogenesis perhaps causes a temporarily negative effect on the condyle, which will undergo a long remodification process to be resumed.2.1mmunohistochemical study of type I and III collagen in condyle in mandibular distraction osteogenesisResults: The expression of type I collagen increased more slowly. On the other hand, type III collagen in condylar cartilage was enhanced after the completion of the distraction. The expression of the type III collagen rose its summit at the 4th week, and then declined.Conclusion: The changes of type I and Illcollagen may indicate the remodeling of temporomandibular joint after the mandibular distraction osteogenesis by stimulating the collagen synthesis and the secretion of cartilage cells.3.Histochemical study on the mandibular condyle in distraction osteogenesisResults: The proteoglycan expression was weaken as well as collagen after the completion of the distraction and got to its minimum at the 4th week, and then increased.Conclusion: Mandibular distraction osteogenesis may cause the change of the extracelluar matrix in mandibular condyle, which exists in the remodelingof temporomandibular joint.From this study, we can conclude that the mandibular condyles go through a process of extracelluar matrix alteration and remodiflcation during distraction osteogenesis. A new balance will be established in mandibular condyle to maintain its relatively normal function.