小型猪一侧失牙及义齿修复后颞下颌关节的组织病理学观察

Histopathological investigation of miniature pig's TMJ following one side teeth missing and denture restoration

目的:观察一侧失牙及义齿修复对小型猪颞下颌关节(temporomandibular joint,TMJ)组织结构的影响。方法:11只小型猪随机分为空白组(2只)、拔牙组(4只)、修复组(5只),将拔牙组和修复组左侧后牙全部拔除,修复组并于拔牙后3个月进行义齿修复。小型猪一侧失牙6个月时处死,解剖TMJ并制作光镜(HE染色)和透射电镜标本,观察其组织结构改变。结果:拔牙组和修复组小型猪双侧TMJ均发生不同程度的退行性改变。髁突软骨表面带玻璃样变性、断裂、剥脱;肥大带下陷成乳突样,软骨细胞成簇;骨小梁破坏呈蚕蚀状。关节盘胶原纤维变性、紊乱、断裂,盘后组织出现明显软骨化生。髁突软骨瘀斑、凹陷、剥脱的超微病理特征分别是细胞变性、凋亡、坏死。结论:长期一侧失牙可导致双侧TMJ退行性变,及时义齿修复可减轻TMJ的病理损伤。

Objective： To investigate the histopathological response of temporomandibular joint （TMJ） in miniature pig following missing one side posterior teeth and denture restoration. Methods： 11 adult female normal miniature pigs were randomly divided into 3 groups： group Ⅰ- control group （2 pigs）, group Ⅱ （4 pigs）, group Ⅲ （5 pigs）. In group Ⅱ and Ⅲ, pigs＇left posterior teeth were pulled out. Dentures were fabricated for the pigs in group Ⅲ 3 months after teeth missing. 6 months after teeth extraction, the animals were killed and the sections of condyles and discs of TMJs were observed by light microscopy （H.E staining） and electron microscopy respectively. Results： Obvious degenerative changes were found in all TMJs of the experimental pigs. The fibrous articular layer of condylar cartilage showed the hyaline degeneration, fragment and loss. Mastoid structure could be formed in the hypertrophic layer which separated the chondrocytes into islands. The condylar bone was damaged by the osteoclasts. The discs presented hyaline change, irregular running and rupture, chondroitic metaplasia was marked in the retrodiscal tissue. The ultrastructures of ecchymosis, cave, partial loss of condylar cartilage were characterized by degeneration, apoptosis and necrosis respectively. Conclusion： A long-term unilateral tooth-loss could lead to the degenerative changes of bilateral TMJs, however the denture restoration in time could alleviate the damage to the TMJs.