Whetten L L, Johnston L E
Am J Orthod. 1985 Sep;88(3):181-90. doi: 10.1016/s0002-9416(85)90213-1.
The present study used 21 male albino rats to test the hypothesis that lateral pterygoid traction regulates the growth of the mandibular condyle. The condyles, the rami, and the top of each glenoid fossa were marked with metallic implants, and, following bilateral section of the condylar neck, one lateral pterygoid muscle was extirpated. On the basis of the literal details of Petrovic's cybernetic model, it was assumed that the continued forward growth of the midface and the backward translation of the glenoid fossa would combine to produce a progressive disturbance in the buccal occlusion that would, in turn, generate a reflex contraction of the remaining lateral pterygoid muscle. Initially, however, growth of the isolated condyles would have little impact on the spatial position of the rest of the mandible. As a result, the condyles on the side with the intact lateral pterygoid should grow for a time at a maximal, open-circuit rate, whereas the experimental condyle, deprived of all muscle traction, should show only a minimal "commanded" rate of growth. The serial change in the position of the condylar and ramal implants was assessed cephalometrically for 6 weeks, and between-sides differences were analyzed by randomized block analysis of variance. The presence or absence of the lateral pterygoid muscle had no significant effect on the anteroposterior position of the condylar implants and only a slight, transitory effect on their vertical position. The translation of the ramal implants, however, was greatly affected by the condylotomy. On both control and experimental sides, the mandible collapsed upward and backward until contact between the growing condyle and ramus had been achieved, whereupon a downward and forward pattern of translatory growth was re-established. Although it could not be shown that lateral pterygoid traction per se is a significant factor in the growth of isolated condyles, it was concluded that the condyle is vitally important to the translatory growth of the mandible as a whole. On the basis of these data and the current literature, a simple hypothesis was advanced for the control of condylar growth by the ongoing pattern of functional loading and for the role of this growth in the normal downward and forward displacement of the rest of the mandible.
本研究使用21只雄性白化大鼠来检验翼外肌牵引调节下颌髁突生长这一假说。在髁突、下颌支以及每个关节窝顶部植入金属标记物，双侧髁突颈部截断后，切除一侧翼外肌。基于彼得罗维奇控制论模型的文字细节，假定面中部持续向前生长以及关节窝向后移位会共同导致颊侧咬合逐渐紊乱，进而引起剩余翼外肌反射性收缩。然而，最初孤立髁突的生长对下颌骨其余部分的空间位置影响很小。因此，翼外肌完整一侧的髁突应在一段时间内以最大开路速率生长，而缺乏所有肌肉牵引的实验侧髁突应仅表现出最小的“指令性”生长速率。通过头影测量法评估髁突和下颌支植入物位置的连续变化，为期6周，并采用随机区组方差分析来分析两侧差异。翼外肌的有无对髁突植入物的前后位置没有显著影响，对其垂直位置仅有轻微、短暂的影响。然而，下颌支植入物的移位受髁突截断术的影响很大。在对照侧和实验侧，下颌骨均向上和向后塌陷，直至生长中的髁突与下颌支接触，随后重新建立向下和向前的移位生长模式。尽管无法证明翼外肌牵引本身是孤立髁突生长的重要因素，但得出的结论是，髁突对整个下颌骨的移位生长至关重要。基于这些数据和当前文献，提出了一个简单的假说，即通过持续的功能负荷模式来控制髁突生长，以及这种生长在正常情况下对下颌骨其余部分向下和向前移位的作用。
