Diagnosis
Pain is the most common reason for people with TMD to seek medical advice. Joint noises may require auscultation with a stethoscope to detect. Clicks of the joint may also be palpated, over the joint itself in the preauricular region, or via a finger inserted in the external acoustic meatus, which lies directly behind the TMJ. The differential diagnosis is with degenerative joint disease (e.g. osteoarthritis), rheumatoid arthritis, temporal arteritis, otitis media, parotitis, mandibular osteomyelitis, Eagle syndrome, trigeminal neuralgia, oromandibular dystonia, deafferentation pains, and psychogenic pain. Diagnostic criteria
Various diagnostic systems have been described. Some consider the Research Diagnostic Criteria method the gold standard. Abbreviated to "RDC/TMD", this was first introduced in 1992 by Dworkin and LeResche in an attempt to classify temporomandibular disorders by etiology and apply universal standards for research into TMD. This method involves 2 diagnostic axes, namely axis I, the physical diagnosis, and axis II, the psychologic diagnosis. Axis I contains 3 different groups which can occur in combinations of 2 or all 3 groups, (see table). McNeill 1997 described TMD diagnostic criteria as follows:
Pain in muscles of mastication, the TMJ, or the periauricular area (around the ear), which is usually made worse by manipulation or function. Asymmetric mandibular movement with or without clicking. Limitation of mandibular movements.
It is the gold standard method for assessing disc position and is sensitive for intra-articular degenerative alterations.Indications for MRI are pre-auricular pain, detection of joint clicking and crepitus, frequent incidents of subluxation and jaw dislocation, limited mouth opening with terminal stiffness, suspicion of neoplastic growth, and osteoarthritic symptoms. It is also useful for assessing the integrity of neural tissues, which may produce orofacial pain when compressed.MRI provides evaluation of pathology such as necrosis and oedema all without any exposure to ionizing radiation. However, there is a high cost associated with this method of imaging, due to the need for sophisticated facilities. Caution should be taken in patient selection, as MRI is contraindicated in those with claustrophobic tendencies, pacemakers and metallic heart valves, ferromagnetic foreign bodies and pregnant women. Ultrasound
Where internal TMJ disorders are concerned, ultrasound (US) imaging can be a useful alternative in assessing the position of the disc While having significant diagnostic sensitivity, US has inadequate specificity when identifying osteoarthrosis. Moreover, it is not accurate enough for the diagnosis of cortical and articular disc morphology based on the findings done related to morphological alterations. However, with US, identification of effusion in individuals with inflammatory conditions associated with pain is possible and confirmed by MRIUS can be a useful alternative in initial investigation of internal TMJ dysfunctions especially in MRI contraindicated individuals despite its limitations.