Comparison of magnetic resonance imaging before and after nonsurgical treatment of closed lock.

Ten temporomandibular joints with the closed lock in 10 patients who were successfully treated clinically nonsurgically with the occlusal splint, were studied with magnetic resonance imaging. In all patients, the pretreatment images of temporomandibular joints showed anteriorly dislocated disks that failed to recapture together with various changes in disk morphology. Three to four months after the treatment, all patients could open their mouths more than 47 mm at the incisor position and were asymptomatic. But the follow-up magnetic resonance images showed that the disks were still anteriorly displaced and deformed and their relationships with the condyles were unchanged. The reestablishment of mouth opening appeared to occur not by recapturing of the disks but by improvement in condylar mobility and the adaptation of the posterior attachment.