Study Of The Effect Of Occlusal Vertical Rising On The Condylar Cartilage Histological Featuers And The Expression Of PCNA And BMP-2 In Adolescent Rats

The changes of occlusion have substantial effects on stomatognathic system function and craniofacial growth. Clinically, the occlusal Viertcial rising has been used to treat deep overbite, sleep bruxism, temporomandibular joint disorder, et al. At present, there are scarely studies in effects of the changes of occlusal vertical rising on temporomandibular joint, And there are different views in the effect of occlusal vertical rising on inducing condylar cartilage remodeling. Forty five-week-old male Sprague-Dawley (SD) rats were divided randomly into experimental group (n=20) and control group (n=20). Animals in experimental group were fitted with the upper posterior bite rising splints on their bilateral upper molars. The animals of experimental group, together with their matched control, were sacrificed 7, 14, 21d and 28d after the appliance insertion (n=5 per group each time). Sections were cut from right condyles. Then, HE and Ponceau staining and immunohistochemistry for PCNA and BMP-2 were applied to evaluate the effect of occlusal vertical rising on the remodeling of condylar cartilage, and it may offer the experimental basis for the clinical therapy.The study consists of two parts:1. Effect of occlusal vertical rising on condylar cartilage remodeling in adolescent rats.RESULTS:In comparison with control group, 7 and 14d after the appliance insertion, the condyle cartilage thickness decreased significantly in the experimental group(P﹤0.05). 28d after the appliance insertion, the condyle cartilage thickness in the posterior region increased significantly in the experimental group(P﹤0.05)and new formed bone were found in the posterior region of the condyle cartilage in the experimental group but not in the control group.2. Effect of occlusal vertical rising on the expression of PCNA and BMP-2 in condylar cartilage of adolescent rats.RESULTS:PCNA was predominantly localized in proliferative zone and upper hypertrophic zone in condylar cartilage. BMP-2 was predominantly localized in hypertrophic zone in ondylar cartilage. In comparison with control group, 7 and 14d after the appliance insertion, the positive cells of PCNA and BMP-2 in condyle cartilage were significant less in the experimental group(P﹤0.05). After that, the expression increased gradually. 21 and 28d after the appliance insertion, the positive cells of PCNA and BMP-2 in condyle cartilage were significant more in the experimental group(P﹤0.05). CONCLUSION:The occlusal vertical rising could lead to adaptive remodeling activities of condyle cartilage in adolescent rats. The condyle cartilage thickness and new formed bone in the posterior region increased significantly in the experimental group. The positive cells of PCNA and BMP-2 in condyle cartilage were significant increased,which might play an essential role in the remodeling of condyle cartilage.