The Experimental Study On The Relationship Between The Treatments Of Intracapsular Condylar Fractures And TMJ Ankylosis

Objective: The aim of this study was to elucidate the relationship between different treatments of intracapsular condylar fractures and the formation of traumatic temporomandibular joint(TMJ)ankylosis.Experimental data help us to explore the mechanism of temporomandibular joint ankylosis secondary to intracapsular condylar fractures and guide us to choose the optimized treatment methods.Reliable data were also got to clarify the preventive mechanism of traumatic temporomandibular joint ankylosis.Methods: In this study,miniature porcine animal model was established to simulate intracapsular condylar fractures.Based on different treatment methods,the animals were subdivided into four groups: normal saline group,dexamethasone group,miniature titanium plate fixation group as experimental groups and natural healing group as control group.1.6 months postoperatively,the formation of TMJ ankylosis was evaluated by gross specimen observation,imaging and histological examination.2.The expressions of VEGF,OCN,OPN and BMP2 in TMJ specimen were detected by immunohistochemical staining.3.The mRNA and protein expressions of VEGF,OCN,OPN and BMP2 in TMJ specimen were detected by RT-PCR and Western Blot respectively.Results:1.The incidence of temporomandibular joint ankylosis in the experimental group was significantly lower than that in the control group by gross specimen observation,imaging and histological examination(P <0.05).2.The mean optical density value of VEGF,OCN,OPN and BMP2 in the experimental group was significantly lower than that in the control group by immunohistochemical staining(P <0.01).3.The mRNA expression level of VEGF,OCN,OPN and BMP2 in the experimental group was significantly lower than that in the control group byRT-PCR(P <0.01).4.The expression level of VEGF,OCN,OPN and BMP2 in the experimental group was significantly lower than that in the control group by Western Blot(P <0.01).Conclusion:1.The animal model of TMJ ankylosis with intracapsular condylar fractures is reproducible,which could provide a platform for exploring the mechanism of traumatic temporomandibular joint ankylosis.2.Different treatment of intracapsular condylar fractures is closely related to the incidence of traumatic temporomandibular joint ankylosis.3.Using rigid internal fixation and disc replacing suture can effectively reduce the occurrence of TMJ ankylosis.4.Dexamethasone local injection in the joint cavity can effectively prevent the formation of TMJ ankylosis.5.Removal of hematoma,reduction of bone wound exposure and inhibition of new bone excessive repair would be the key factors for prevention of TMJ ankylosis.