A classification of temporomandibular joint disk morphology.

Disk morphology has been recognized as an important feature of internal derangements of the temporomandibular joint and as a suspect in functional impediments. A classification of disk shapes was devised by means of corrected lateral cephalometric arthrotomograms and histopathologic sagittal sections. Five basic shapes were identified: bow tie (normal), straight, funnel, bulge, and Y. Statistical analyses were performed. The normal condyle-disk-fossa relationship and slight-to-moderate disk displacement occurred with disk shape 1 (bow tie). Severe disk displacement without reduction occurred predominantly with disk shape 4 (bulge). Beaking of dye in the anterior recess of the inferior joint space was an indicator of abnormal disk morphology and displacement.