The relationship between the degree of disk displacement and ability to perform disk reduction

Objective. To evaluate the difference in temporomandibular joint (TMJ) disk position between reducible and permanently displaced disks. Study design. We found 182 joints with disk displacement (83 with reduction and 99 without reduction) that were available for the study. The disk position was estimated by using magnetic resonance imaging. Results. There was a statistically significant difference between them with the permanently displaced disks being located more anteriorly. When a comparison was made in the disks as to which degree of displacement was moderate, a difference of disk position at either the medial or lateral depth of the TMJ was observed. Conclusion. It was suggested that the permanently displaced disks are located more anteriorly than the reducible displaced disks. When the disk displacement was moderate, disk reduction was influenced by less disk displacement at either the medial or lateral part of the TMJ.