Relative risk of positional and dynamic temporomandibular disc abnormality for osteoarthritis-magnetic resonance imaging study.

Dynamic articular disc abnormality (wR, with reduction; woR, without reduction) is well known as the risk factor for temporomandibular joint osteoarthritis (TMJOA). However, there are few speculations on the potential risk of positional disc abnormalities for TMJOA. The purpose of this study was to investigate the relative risk of positional abnormality and dynamic abnormality of the temporomandibular disc for OA after the three-dimensional interpretation of all the sagittal and coronal planes of magnetic resonance (MR) data in a large dataset of consecutive subjects. Experimental samples consisted of images of 1356 TMJs of patients. A diagnosis of disc state was established in each TMJ utilising a 1.5T MR imaging scanner. A binary logistic regression analysis was performed to identify the significant associations between the outcome (dependent variable: the presence of OA) and the predictors (covariates: age, sex, dynamic disc state [the presence of woR], and 5 categories of the positional disc state [NA, no abnormality; SW, sideways; pADD, partial anterior; cADD, complete anterior; PDD, posterior]). Based on the result of the binary logistic regression analysis, the presence of woR showed an odds ratio of 14.1 (P < .05). In addition, compared with the joints NA, those with SW and cADD showed odds ratios of 5.62 and 10.88, respectively (P < .05). Despite the limitations of the study, in the positional disc abnormalities, sideways disc displacement and complete anterior disc displacement could be associated with the occurrence of TMJOA. All the coronal and sagittal MR images should be evaluated to assess intra-articular joint disorders accurately.