小型猪一侧失牙及义齿修复后颞下颌关节腔内压的测定与分析

Measurement and analysis of intra-articular pressure in temporomandibular joints of miniature pigs following one side posterior teeth extraction and denture restoration

目的观察小型猪一侧失牙及义齿修复后颞下颌关节(temporomandibular joint,TMJ)关节内压(intra-articular pressure,IAP)的波动规律。方法将11只小型猪随机分为空白组(2只)、拔牙组(4只)和修复组(5只),将拔牙组和修复组小型猪左侧上下后牙全部拔除,修复组并于拔牙后3个月进行义齿修复,利用钛钉骨内种植的方法固定义齿。对3组小型猪双侧TMJ在3个功能位的IAP进行测定(每月1次,共6个月);并在每月同一时间记录其体重变化。结果一侧失牙不及时修复可造成双侧TMJ IAP的失调:休息位不再维持均衡的负压;被动开口出现异常增大的负压;被动闭口出现较高正压;开闭口后不能完全或只能缓慢回到原休息位压力水平;对侧牙齿严重磨耗。一侧失牙3个月后及时义齿修复可明显改善双侧TMJ IAP的失调状况:休息位恢复负压;被动开口为增大的负压;被动闭口升高为正压;开闭口后能迅速回到原休息位压力水平;左右侧压力变化协调一致;对侧牙齿磨耗减轻。3组小型猪体重变化比较P=0.064>0.05,无组间差异。结论一侧失牙可破坏咬合、TMJ、咀嚼肌的平衡,及时义齿修复可调节三者不协调的关系,使之重建新的平衡。

Objective To survey the fluctuating curve of intra- articular pressure （IAP） in temporomandibular joints（ TMJ ） of miniature pigs following one side posterior teeth extraction and denture restoration. Methods 11 adult female normal miniature pigs were randomly divided into 3 groups： group Ⅰ -control group （2 pigs）, group Ⅱ - tooth - extraction without denture restoration （4 pigs）, group Ⅲ -tooth -extraction with denture restoration （5 pigs） . In group Ⅱ and Ⅲ, pigs＇left side upper and lower posterior teeth were pulled out. Co - Cr casting dentures were fabricated for the pigs in group Ⅲ 3 months after teeth missing; the dentures were fixed by implanting titanium nails through the base plate into the alveolar bone. TMJ IAPs of both sides were determined montldy at 3 jaw positions respectively; meanwhile , the weight of pigs were measured to monitor their growth. The experiment period was 6 months. Results Compared with controls, the imbalance of bilateral pressure in group II was showed： the IAP at rest could not maintain subatmospheric identically on both sides; during operator- assisted opening movement, the negative IAP was significantly lower;however, when the jaw was closed , the IAP increased to a higher positive level; and the pressure could not return to baseline or slowly decayed to original values ; the severe attrition of teeth in working side was found out. The pressure values of group III indicated that the treatment with denture timely could evidently improve the asymmetric conditions： IAP resumed to be subatmospheric;as the jaw was opened, a negative pressure was presented followed by an increased positive pressure while the mouth was closed; the IAP could immediately decayed to baseline after jaw movement; the bilateral IAP was close to equality and balance ; the attrition of teeth was alleviated. During the 6 months, the pigs maintained their weight within the normal range and grew healthily. Conclusion Missing one side teeth could disturb the balance of occlusion,TMJ and masticatory muscles; on the other hand , denture restoration could regulate the unbalanced relation and make them harmonious.