下颌骨功能性偏斜对发育期大鼠髁突软骨胶原改建的影响

Characterization of Mandibular Condylar Cartilage Collagen Response to Functional Lateral Deviation of the Mandible

目的:观察下颌骨功能性偏斜对发育期大鼠髁突软骨内I型、II型以及III型胶原纤维分布及表达的影响。方法:取4周龄雄性SD大鼠40只,随机分为实验组(20只)和正常对照组(20只)。实验组佩戴自制的上切牙金属牙套引导下颌骨功能性右偏,对照组不佩戴任何装置,分别于实验1周、4周取得标本。HE染色及番红-O染色观察髁突软骨组织形态,苦味酸-天狼猩红偏振光染色以及免疫组化染色分别观察髁突软骨内I型、II型、III型胶原纤维含量以及分布表达情况,并进行相关半定量图像分析。结果:HE以及番红-O染色显示,实验1周后实验组牵张侧较正常组髁突软骨厚度显著增加,到4周后两组差异不显著;而实验组受压侧髁突软骨厚度4周后显著下降。天狼猩红染色及免疫组化染色结果显示,I型胶原主要表达在增殖层至成骨细胞层,II型胶原主要表达在软骨细胞层和肥大层。与正常组相比,1周及4周时实验组牵张侧软骨中区I型及II型胶原表达增强;受压侧软骨后区I型及II型胶原表达均显著减少。III型胶原主要表达在软骨纤维层至软骨细胞层,两组间无显著表达差异。结论:下颌骨功能性偏斜导致两侧髁突软骨发生了差异性生长改建,I型及II型胶原参与了改建中软骨内骨化过程。

Objective： This study was designed to examine condylar bone response to lateral functional shift of the mandible by examining the changes of type I/II/III collagen. Methods： Male Sprague-Dawley rats aged 4 weeks （n=40） were randomly divided into 2 groups （n=20 in each group）. Rats in experiment group wore intraoral positioners, which could shift the mandibular postural position asymmetrically, whereas for the control rats no appliances were fitted. The rats were sacrificed at 1 and 4 weeks respectively. The condylar histomorphology was analyzed by hematoxylin eosin staining and safranin O staining. Picric acid-sirius red staining and immuohistochemical method were used to determine the relative content and local changes of type I/II/III collagen and then for hemi-quantitative imaging analyses. Results： Hematoxylin eosin staining and safranin O staining showed that in the experimental group, total condylar cartilage thickness on the re- gions of the contralateral side significantly increased after 1 week of functional deviation, while the total cartilage thickness on three investigated regions had no significant difference at 4 weeks. However, total condylar cartilage thickness on the three regions of the ipsilateral side had significantly decreased at 4 weeks. Results of Picric acid-sirius red staining and immuohistochemical method indicated that positive findings for type I collagen were observed from fibrous layer to chon- drocyte layer, and type II collagen were mainly observed in chondrocyte layer and hypertrophic layer. As compared with the control group, the expression of type I and type II collagen in the central region of the contralateral condyle increased significantly on 1 week and 4 weeks, while that in the lateral region of the ipsilateral condyle continued to decrease on 1 week and 4 weeks. Positive findings for type Ill collagen were observed from fibrous layer to chondrocyte layer, no signifi- cant differences were identified between the experimental and control groups. Conclusion： It is suggested that each side of the condylar cartilage was altered differently by functional lateral deviation of the mandible, and type I and type II collagen appeared to involve in intraeartilaginous ossification during the cartilage growth and remodeling process.