Magnetic resonance imaging findings of internal derangement in temporomandibular joints without a clinical diagnosis of temporomandibular disorder.

The purpose of this study was to assess the prevalences of magnetic resonance (MR) imaging findings of internal derangement (ID) in temporomandibular joints (TMJs) without a specific clinical diagnosis of temporomandibular disorder (TMD), and to investigate whether in this TMJ group the variable of pain may be linked to MR imaging findings of ID. The study comprised 109 patients, who were assigned a clinical uni- or bilateral TMJ-related diagnosis of 'absence of TMD'. Bilateral sagittal and coronal MR images were obtained subsequently to establish the prevalence of TMJ ID. An MR imaging diagnosis of ID was found in 99 (55.9%) of the 177 TMJs investigated. About 30.3% of the closed mouth-related TMJ positions characterized by disc displacement presented with anterior disc displacement, while 27.3% had anterolateral and 25.3% anteromedial disc displacement. Analysis of the data revealed the presence of TMJ pain to be associated with significantly more MR imaging diagnoses of disc displacement without reduction than disc displacement with reduction (P < 0.05), while there was no significant difference in the prevalences of ID and those of absence of ID (P > 0.05). Using chi-square analysis, no significant relationship was found between the presence of TMJ pain and the MR imaging diagnosis of TMJ ID (P=0.93). Use of the kappa statistical test indicated poor diagnostic agreement between the presence of TMJ pain and the MR imaging diagnosis of ID (kappa=0.01). The results suggest TMJs with a clinical diagnosis of 'absence of TMD' to be associated with a high rate of IDs, while in these instances the clinical variable of TMJ pain may have no effect on prevalences of MR imaging diagnoses TMJ ID. The data confirm the aspect of clinical diagnostic criteria as an unreliable instrument in predicting MR imaging diagnoses of TMJ ID.