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 posi tion 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 comp arison was made in the disks as to which degree of displacement was moderat e, a difference of disk position at either the medial or lateral depth of t he TMJ was observed. Conclusion. It was suggested that the permanently displaced disks are locat ed more anteriorly than the reducible displaced disks. When the disk displa cement was moderate, disk reduction was influenced by less disk displacemen t at either the medial or lateral part of the TMJ.