Hiroyuki Kai

Clinical symptoms of open lock position of the condyle. Relation to anterior dislocation of the temporomandibular joint.

Nine cases of open lock position of the condyle of the temporomandibular joint (TMJ) are reported. In two patients recurrent dislocation of the TMJ was diagnosed clinically, and four had previous episodes of anterior dislocation. An arthrotomographic examination revealed that the condyles of the affected TMJs were located anterior to the anterior bands of the disks at an open-mouth position. An arthrographic fluoroscopic examination showed that the anterior bands mechanically obstructed the anteriorly displaced condyles from posterior movement into the articular fossae to various degrees at open-mouth position. One cause of anterior dislocation of the TMJ is thought to be fixation of the condyle in the open lock position resulting from a disturbance of a neuromuscular mechanism. In the two patients with dislocation, occlusal treatment eliminated muscular symptoms and the dislocations completely disappeared.

The Significance of Posterior Open Bite After Anterior Repositioning Splint Therapy for Anteriorly Displaced Disk of the Temporomandibular Joint

Spontaneous posterior open bite was observed in 15 patients after the application of anterior repositioning splints in the treatment of anteriorly displaced disk. Recapture of the disk after treatment was clinically diagnosed in five patients. Arthrography performed on 10 patients with open bite revealed a completely recaptured disk in four patients, an anteriorly displaced disk without reduction in four patients, and an anteriorly displaced disk with reduction in two patients. This suggests that recapture of the disk in the correct position at mouth closing should be a major cause of the posterior open bite in patients who have a relatively short duration of locking and successful mandibular manipulation. Although the cause of posterior open bite with the persistently displaced disk is still unclear, an increase in the posterosuperior joint space by the posterior open bite appears to eventually produce favorable effects to joints with anteriorly displaced disks.

Tardive dyskinesia affected by occlusal treatment--a case report.

The following is a case report of occlusal treatment for involuntary mandibular movement occurring in a 79-year old woman. This was diagnosed as sulpiride-induced tardive dyskinesia. The patient had been treated with sulpiride to improve gastrointestinal symptoms for five years until the onset of involuntary mandibular movement. The involuntary movement worsened even after discontinuation of the drug for 10 weeks. The dyskinesia improved in the course of treatment with an occlusal splint placed over her upper denture. After wearing the new denture with increased occlusal vertical dimension, the dyskinesia disappeared almost completely. Sirognathographic observation showed that previous denture wear evoked remarkable involuntary movement of the mandible once again. It is uncertain whether such improvement may result from discontinuation of the drug or from the occlusal treatment. However, it appears that occlusal factors played an important role in orofacial manifestation of tardive dyskinesia (TD) in this case.