[Arthrography of recurrent dislocation of the TMJ--with special reference to the movement of the articular disk].

To investigate the movement of the articular disk in recurrent luxations, 4 temporomandibular joints in three patients were studied with the arthrotomographs. All the superior articular cavities were extended anteriorly. On the mouth open in two patients with recurrent subluxation, the mandibular head accompanied with the articular disk located very anterior position from the articular tubercle. At this time, the retro-discal pad were stretched, but the relation between mandibular head and articular disk were normal findings: the mandibular head located on the central thin part of the articular disk. One of them showed anterior disk displacement with reduction. The other patient showed the bone cavity at the anterior slope of the articular tubercle. On the mouth open, the mandibular head and posterior band fitted that cavity. The other hand, remaining one patient was recurrent luxation on the left side. On the mouth open, the relation between mandibular head and articular disk were abnormal findings: The mandibular head located very anterior position, over the articular tubercle and anterior band of the disk. Therefore, the inferior articular cavity was extended, but the retro-discal pad was not stretched. The anterior slope of the articular tubercle was steep. The other side TMJ of this patient was recurrent subluxation and anterior disk displacement with reduction. On the mouth open, it was showed the hypermobility of mandibular head. But the relation between mandibular head and articular disk were normal findings. As mentioned above, in luxation and subluxation, it was made obvious that there were tow types about the relation between mandibular head and articular disk on the mouth open: one type was that mandibular head located anteriorly to the anterior band of the disk, the other was under the disk.