A study of the relationship between the position of the condylar head and displacement of the temporomandibular joint disk

Objectives: To examine the possible relationship between condylar position and disk displacement in the TMJ. Methods: Forty-eight joints with no disk displacement (NDD), 84 joints with a reducible displaced disk (RDD) and 99 joints with a permanently displace d disk (PDD) were selected. The positions of the condyle and TMJ disk were calculated from lateral MR, images. Results: There were significant differences in condylar position between ti le joints with NDD and RDD. while there was no difference between those wit h NDD and PBD (Kruskal-Wallis and post-hoc test. P<0.05). There was also a significant correlation between the position oi the condylar and the displa ced disk (Spearman's rank correlation P<0.05). The condyle was located more anteriorly with advancing disk displacement. Conclusions: We suggest that if the disk displacement is slight. the condyl e is displaced posteriorly: as the disk displacement becomes mol-e sevel e (i.e. more anteriorly displaced) :he condyle returns to the concentric posi tion.