Articular Disc Position and Configuration in Internal Derangement of Temporomandibular Joint

Abstract

Internal derangement of the temporomandibular joint (TMJ) is defined as a malrelationship among the condylar process, mandibular fossa, and articular disc. It produces changes of the disc position and configuration. Magnetic resonance imaging (MRI) is an excellent radiographic method for the primary diagnostic evaluation of TMJ internal derangement, especially for confirming the disc displacement and deformation. The purpose of this study was to evaluate the relationship between the disc position and configuration in the closed and open mouth positions according to the degree of disc displacement and deformation. Of 131 joints with TMJ internal derangement from 98 patients, anterior displacement without reduction of the articular disc was found in 65 joints (49.6%), and deformed disc in about 75.0%. All of the articular discs diagnosed as anterior displacement without reduction of the articular disc accompaning osteoarthrosis, were severely deformed. The disc deformation was preceded by anterior displacement of the articular disc and degenerative change of the condylar process. The more the disease process of TMJ internal derangement became worse, the more the articular disc was anteriorly displaced and severely deformed. Therefore, it was concluded that early treatment of TMJ disorder may decrease the disc displacement and deformation.