Coordinated movements of the mandibular condyle and the articular disk in decreased occlusal vertical dimension in rabbit.

在咬合垂直距离减小时，记录下颌运动和肌电图活动。并对下颌髁突运动与咬合关系的变化进行了研究。本实验通过观察下颌髁突在关节结节方向上的运动对下颌骨应力的影响，初步探讨了磨牙区切除对下颌骨应力的影响。在结节切削侧为工作侧的情况下，在咬合阶段随着向前突出而引起的运动修正。此外，运动轨迹转移在一个前上方的方向在此期间，当活动的颌骨关闭肌肉不发生作为开放阶段。这说明关节结节是通过闭合颌肌的静息张力和皮肤的弹性力来承受应力的。在同侧磨牙区截骨时，牙合期前伸运动量增加，运动轨迹前移。颞下颌关节紊乱病的发病机制被认为是多因素的，如咬合异常、肌张力增高、生活习惯、精神压力等。然而，异常的应力负荷和异常的颌骨运动是导致颞下颌关节形态缺损和关节盘位置异常的必要条件，本研究有望在揭示关节盘前脱位的发病机制方面发挥重要作用。

In decreased occlusal vertical dimension, jaw movement and electromyogram activity were recorded. And we studied the relation between movements of the mandibular condyle and alteration of occlusion. The experiment which after cut the articular tubercle visualizes stress as mandibular condyle movement in the articular tubercle direction was conducted as preliminary step for investigate influence of cut the molar region. In tubercle cutting side was working side case, modification in the movement caused as project forward in occlusal phase. Additionally, trajectory of motion shifted in an anterosuperior direction in the period when activity of the jaw closing muscle does not occur as opening phase. This shows that articular tubercle received stress by resting tension of jaw closing muscle and elastic force of skin. Moreover when cut the molar region on the ipsilateral side, project forward movement in occlusal phase and trajectory of motion forward shift increased. This suggest that stress for articular tubercle increased.Pathogenesis of temporomandibular disorder is considered multifactor, for example, occlusal abnormality, increase in muscle tone, lifestyle habit, mental stress. However, abnormal stress loading and abnormal jaw movement are essential for morphological defect of temporomandibular joint and abnormal position of articular disk.This studies are expected to play an important role in revealing the pathogenesis of anterior dislocation of articular disk.