Changes in disc position, disc length, and condylar height in the temporomandibular joint with anterior disc displacement: a longitudinal retrospective magnetic resonance imaging study.

PURPOSE: To quantitatively assess the changes in disc position relative to the condyle, disc length, and condylar height, with magnetic resonance imaging in patients with anterior disc displacement of the temporomandibular joint who had received no treatment, to provide useful information regarding treatment planning.

PATIENTS AND METHODS: The study included 83 joints in 62 patients. The joints were assessed quantitatively for the disc position relative to the condyle, disc length, and condylar height on magnetic resonance imaging scans of the temporomandibular joint at initial and follow-up visits. Student t tests were used to assess the statistical significance of the changes.

RESULTS: The mean age at first visit was 30.4 years. The mean follow-up interval was 10.9 months. Thirty-nine joints were shown to have disc displacement with reduction at the initial visit. Of these joints, 27 changed to having disc displacement without reduction after follow-up. The mean disc position relative to the condyle changed from 5.28 to 6.73 mm, whereas the mean disc length changed from 8.31 to 6.91 mm and the mean condylar height from 5.21 to 4.65 mm. Differences were all statistically significant.

CONCLUSIONS: The disc would likely become more anteriorly displaced and shortened and the condylar height would decrease during its natural course. However, further stratified studies with longer follow-up are necessary.