関節円板に由来する閉口末期の閉口障害

Abstract

We report seven cases of mouth closing disturbance caused by the disc of the temporomandibular joint during the final phase of occlusion. The diagnosis was based on the results of magnetic resonance imaging or arthrographic imaging. Two of the seven patients had posterior disc displacement without reduction, while one had the same condition with reduction and the remaining four had posterior folding of the retrodiscal tissue.The patients with posterior disc displacement had a history of luxation, open lock, or both, suggesting that the mouth closing disturbance may have been caused by loosening of the lateral and medial attachments of the disc to the condyle as well as by excessive anterior movement of the condyle. The cases of posterior folding of the retrodiscal tissue were apparently related to anterior disc displacement. This condition, which was similar to the posterior open bite that occurs during anterior repositioning splint treatment for internal derangement, apparently occurred spontaneously.An important point in distinguishing between posterior folding of the retrodiscal tissue and posterior disc displacement is whether the patient has a past history of reciprocal clicking.