渐进性咬合紊乱导致兔髁突退行性变的研究

Study on the effect of gradually induced disordered occlusion on the condyle of New Zealand Rabbit TMJ

目的 探讨渐进性咬合紊乱是否可导致兔髁突软骨退行性变。方法 2 7只 5月龄雄性新西兰大白兔 ,随机分为渐进性咬合紊乱组 (A组 )、操作对照组 (B组 )和空白对照组 (C组 )。A组动物以正畸用橡皮圈分别将一侧上颌和对侧下颌第一前磨牙向近中牵拉 ,以形成上下牙不吻合接触的咬合紊乱 ;B组作结扎钢丝操作对照 ,不牵拉。分别在 6月龄、7月龄、8月龄时取材 ,各时间点每组取材 3只实验动物 ,对双侧髁突作组织学观察和测量。结果 B、C两组髁突软骨表现无明显差异 ,A组有明显随时间延长而加重的退行性变 ,表现为髁突前、中部软骨变薄 ,肥大层软骨不连续 ,局部组织纤维化 ;髁突后部软骨增厚 ,增殖层未成熟细胞比例增加。结论 渐进性咬合紊乱可导致兔髁突软骨退行性变。

Objective To investigate whether the gradually induced disordered occlusion can induce degenerative changes in rabbit TMJ. Methods 27 male New Zealand Rabbits, age of 5 months were divided equally and randomly into three groups: Group A: One premolar in upper dentition at one side and another premolar in lower dentition at the other side were pulled to move medially to the anterior intrinsic space by an orthodontic string to cause the corresponding premolars not to occlude with the opposites coincidently. Group B: the sham operating controls, all animals were treated similar to those in Group A but without pulling. At the age of 6, 7 and 8 months , three rabbits of each group were killed by deeply anaesthetizing and bilateral condyles of TMJs were excised, sectioned and stained with HE. Results There was no significant histological difference in condylar cartilage between Group B and C. The cartilage of TMJs condyle in Group A was found with significant degenerative changes that increased with age. The thickness of cartilage of anterior and intermediate part of condyles decreased, the disturbance of continuation of hypertrophic layer appeared and part of hypertrophic layer was locally replaced by fibrous tissue. While the thickness of cartilage of posterior part of condyle increased obviously with a significant increase of the proportion of immature chondrocytes. Conclusion The gradually induced disorder occlusion may lead to degenerative changes in rabbit condyle .