Risk factors for temporomandibular joint pain in patients with disc displacement without reduction – a magnetic resonance imaging study

summary The purpose of this study was to evaluate whether the magnetic resonance (MR) imaging variables of temporomandibular joint (TMJ) internal derangement, osteoarthrosis and/or effusion may predict the presence of pain in patients with a clinical disorder of an internal derangement type (ID)‐III. The relationship between TMJ ID‐III pain and TMJ internal derangement, osteoarthrosis and effusion was analysed in MR images of 84 TMJs in 42 patients with a clinical unilateral diagnosis of TMJ ID‐III pain. Criteria for including a TMJ ID‐III pain patient were report of orofacial pain referred to the TMJ, with the presence of unilateral TMJ pain during palpation, function and/or unassisted or assisted mandibular opening. Bilateral sagittal and coronal MR images were obtained to establish the presence or absence of TMJ internal derangement, osteoarthrosis and effusion. Using chi‐square analysis for pair‐wise comparison, the data showed a significant relationship between the MR imaging findings of TMJ ID‐III pain and those of internal derangement ( P =0·01) and effusion ( P =0·00). Of the MR imaging variables considered simultaneously in the multiple logistic regression analysis, osteoarthrosis ( P =0·82) and effusion ( P =0·08) dropped out as non‐significant in the diagnostic TMJ pain group when compared with the TMJ non‐pain group. The odds ratio that a TMJ with an internal derangement type of disk displacement without reduction might belong to the pain group was strong (2·7:1) and highly significant ( P =0·00). Significant increases in risk of TMJ pain occurred with ‘disk displacement without reduction in combination with osteoarthrosis’ (5·2:1) ( P =0·00) and/or ‘disk displacement without reduction in combination with osteoarthrosis and effusion’ (6·6:1) ( P =0·00). The results suggest that TMJ pain is related to internal derangement, osteoarthrosis and effusion. However, the data re‐emphasize the aspect that these MR imaging variables may not be regarded as the unique and dominant factors in defining TMJ pain instances.