中文摘要：

目的探讨渐进性咬合紊乱对大鼠髁突软骨中肿瘤坏死因子-α（TNF-α）表达的影响。方法48只8周龄大鼠，随机分为实验组和对照组各4个时间点，雌雄各半，每组3只。以皮筋弹性力推右侧下颌、左侧上颌第一磨牙近中移动，4周后同样方式推右侧下颌、左侧上颌第三磨牙远中移动，造成渐进性咬合紊乱动物模型，实验2、4、6、8周后处死动物。苏木精-伊红染色观察髁突软骨组织学变化及软骨厚度变化，免疫组织化学方法检测和阳性细胞面积百分比法分析髁突软骨中TNF-α．的表达特点。结果实验4、6、8周组髁突软骨均较对照组增厚（P〈0．05），实验组出现以无菌坏死为主的软骨退行性变。TNF-α主要集中表达于髁突软骨的肥大层，实验2、6、8N组表达高于同龄对照组（P〈0．05），实验4周组与同龄对照组之间无差异（P〉0．05），雌雄变化趋势基本相同。结论TNF-α参与了异常咬合所导致的髁突软骨病理性改建活动，随时间延长，咬合紊乱较重者，髁突软骨的分解代谢活动更加明显。

英文摘要：

Objective To investigate the effect of gradually induced disordered occlusion （GIDO） on the expression of tumor necrosis factor-α （TNF-α） in condylar cartilage in rat. Methods Fourty-eight SD rats, aged 8 weeks, were included, and were divided into experimental and control groups randomly, with the same gender distribution. By inserting elastic rubber band the first mandibular lower and maxillary upper molar was moved medially. Four weeks later the third mandibular lower and maxillary upper molars were moved distally with the same method. In this way the GIDO was established in rats. The rats were sacrificed at the end of 2nd, 4th, 6th, 8th week respectively after the application of the GIDO and the temporomandibular joints were stained with HE. The cartilage thickness was measured. The expression of TNF-α in condylar cartilage was examined by immunohistoehemistry and calculated by the percentage of positive cells areas. Results The cartilage thickness increased in 4th, 6th, 8th week subgroups of experimental group（P〈0.05）. Typical degenerative changes were observed in the experimental group. The expression of TNF-α was mainly in the hypertrophic layer of the condylar cartilage. Compared with the age-matched control group, the expression of TNF-α in experimental group increased at the end of 2nd, 6th and 8th week CP〈0.05）, but kept the same level at the end of 4th week （P〉0.05）. Conclusion The present results suggest that TNF-α take part in the procedure of the abnormal remodeling activities of condylar cartilage in GIDO rat model. The catabolism in condylar cartilage in GIDO rats was even obvious when the experimental period was longer with more serious GIDO.