A STUDY ON TMJ DISC POSITION BY MAPPING METHOD

ABSTRACT

According to the autopsy study for the temporomandibular joint disc position, rotation and sideway displacements as well as anterior displacement of TMJ discs are important aspect of internal derangement. There were some trials to suspect anterior and sideway disc displacements through MR images. But the sagittal and the coronal views of MRI could only show the image of cutted slices, these images were not sufficient for showing the entire correlations amomg glenoid fossa, condylar head and articular disc. In this study we combined the images of the each slice of sagittal views like drawing a map, then we could see the interrelations among these three major components of TMJ smore precisely. Applying this method to both asymtomatic volunteers and TMD patients, we classified the interrelationships between condylar head and articular disc of TMJ as twelve types. The distributions are as follows 1. In asymptomatic volunteers cases, normal relations were 65.0%, sideways or rotational displacements without anterior displacement were 20.0%, only anterior displacements were 15.0%, and anterior displacements combined with rotational displacements were 5.0%. 2. In unaffected sides of TMD patients, normal relations were 42.1%, rotational displacements were 11.8% and anterior displacements were 47.0%. 3. In affected sides of TMD patients, normal relations were 10.6%, sideways or rotational displacements were 13.6%, anterior displacements were 75.8%. 4. In asymptomatic volunteers or unaffected sides of TMD patients, pure anterior displacement was more prominent than combined with sideways or rotational displacement, but in affected sides of TMD patients pure anterior displacement was less prominent.