What you can and cannot see in TMJ imaging - an overview related to the RDC/TMD diagnostic system

TLDR

Current RDC/TMD guidelines do not mandate TMJ imaging, and there is no consensus on when imaging should be used to aid diagnosis or treatment. Future RDC/TMD revisions aim to evaluate and define recommended radiographic techniques, calibrate observers, and conduct randomized controlled trials linking imaging findings to therapeutic outcomes. TMJ imaging employs panoramic, plain, conventional CT, cone‑beam CT, arthrography, and MRI techniques. Radiological findings frequently fail to corroborate RDC/TMD clinical diagnoses; tomography best visualizes osseous changes, with CBCT showing promise yet requiring comparative validation, while MRI is preferred for disc imaging but its diagnostic efficacy remains insufficiently supported.

Abstract

In the current version (I) of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD), imaging of the temporomandibular joint (TMJ) is not required for a diagnosis. Research has shown that radiological findings of the TMJ do not always support the clinical findings of the RDC/TMD diagnosis. But imaging should only be performed when it is known that it could contribute to (i) a proper diagnosis and (ii) treatment with a better prognosis. Several techniques are used to image the TMJ: panoramic radiography, plain radiography, conventional and computed tomography (CT), digital volume tomography or cone-beam computed tomography (CBCT), arthrography and magnetic resonance imaging (MRI). Osseous changes are best visualized in tomography, and the newly developed CBCT is a promising method but must be evaluated in a comparative analysis with other tomographic techniques. And although MRI is the method of choice for imaging the disc, a systematic review found the evidence grade for the diagnostic efficacy of MRI to be insufficient. Today, there is no clear evidence for when TMD patients should be examined with imaging methods. Future research designs should be randomized controlled trials where various radiological examination findings are analysed in relation to therapeutic outcome. In future versions of the RDC/TMD diagnostic system, recommended radiographic techniques must be evaluated and defined, diagnostic criteria well defined and observers calibrated.