[Clinical study on treatment of internal derangement of the T.M. joint].

The author has studied on treatment of internal derangement of the temporomandibular joint induced by incision of the retrodiscal ligament, and on an extracapsular surgical treatment method composed of lower repositioning of the mandibular condyle with oblique osteotomy of the ramus on the animals and 5 patients with internal derangement of the T.M. joint. To induce internal derangement on experimental animals, 5 Malaysian monkeys aging around 2 years and weighing about 3kg. were used, the retrodiscal ligament of the left temporomandibular joint was incised, and 1mm lower repositioning surgery of the condyle was performed 3 weeks after. The animals were observed and sacrificed on the 1st, 2nd, 3rd, 4th and 5th weeks thereafter, and the temporomandibular joints and their surrounding tissues were obtained to make microscopic specimens stained with Hematoxylin-Eosin and with Van Gieson method and patient treated by means of lower reposition surgery and 5 patients treated have been observed clinically. And 5 patients treated have been observed clinically. The results obtained were as follows: 1. Internal derangement of the T.M. joint occurred in by resecting retrodiscal ligament. 2. A lots of bone resorption on articular eminence was shown, 1-2 weeks after lower repositioning surgery. 3. Bone healing on articular eminence was shown, 3-5 weeks after lower repositioning surgery. 4. Displased articular disks came back to normal positions by lower repositioning surgery. 5. 5 patients with internal derangement completely treated by application of lower repositioning surgery.