DIAGNOSTIC-VALUE OF 4 CRITERIA TO INTERPRET TEMPOROMANDIBULAR-JOINT NORMAL DISK POSITION ON MAGNETIC-RESONANCE IMAGES

Objective. This study was undertaken to evaluate different criteria to establish normal disk position on magnetic resonance Images. Study de sign. Magnetic resonance image findings of 137 consecutive patients wi th temporomandibular disorders and 23 asymptomatic volunteers were use d in this study. Three calibrated observers interpreted the images ind ividually. Four closed-mouth and 1 open-mouth criteria were tested for their ability to define normal and abnormal temporomandibular joint d isk positions on magnetic resonance images. Results. For the 46 joints in the asymptomatic volunteers, the criterion that yielded the highes t percentage of normal disk position diagnoses was the disk's intermed iate zone (93.5%). Clock face criteria produced the following declinin g percentages of normal disk position diagnoses: 10 o'clock, 82.6%; 11 o'clock, 63.0%; and 12 o'clock, 39.1%. Similar results were obtained for the patients with temporomandibular disorders. In both groups, as the number of normal disk position diagnoses declined, the percentage of joints with a diagnosis of disk displacement with reduction increas ed. Conversely, the percentage of joints with a diagnosis of disk disp lacement without reduction (in the group of patients with temporomandi bular disorders) did not appear to be substantially affected by the 4 closed-mouth disk position criteria. Conclusions. These results sugges t that the intermediate zone criterion for disk displacement is the mo re stringent criterion and the one that would yield the lowest number of false positives when the disk position is being judged in the close d-mouth sagittal view.