I was pleased to see the conclusions presented by Dr. Rüdiger Emshoff and colleagues in "Magnetic Resonance Imaging Predictors of Temporomandibular Joint Pain" (June JADA). I agree with the authors’ findings that temporomandibular joint surgery based on anatomical findings is not warranted, as they are common findings in controls. Specifically, they found disk displacement and osteoarthrosis, or OA, to be common in the control group. These radiographic findings represent functional changes and remodeling based on daily joint loading from para-functional oral habits.
OA is different from osteoarthritis found in other joints of the body. Many providers do not differentiate between the two. On the basis of the criteria for osteoarthritis for other joints of the body as set forth by the American College of Rheumatology,1 joint stiffness and pain after periods of rest that go away after 30 minutes of using the joint must be present. This finding is uncommon in patients with temporomandibular dysfunction, or TMD. Usually, their pain exacerbates with function. This is different from morning jaw stiffness, which usually can be attributed to bruxism and/or sleep position.
One point of contention is a sentence in the article on internal derangements, or IDs: "Several studies have supported the assertion that IDs are associated with the progressive development of radiographically detectable degenerative changes." One of the studies referenced at the end of this sentence supports the opposite; the work by deLeeuw and colleagues2 in a 30-year follow-up study shows that joint changes stabilized, particularly once disk displacement with reduction had occurred.
The authors also conclude that magnetic resonance imaging, or MRI, may not always offer additional diagnostic information to help with the clinical examination. I agree with this. What this means in practice is that ordering advanced imaging without first examining the patient is a waste of time and health care dollars. Unfortunately, many patients report that previous providers would not even examine them unless they first obtained an MRI, a computed tomographic scan, lateral and anteroposterior skull radiographs with open and closed mouth views, and so forth.
The correct way to examine TMD patients is to do a clinical examination first, and then order advanced imaging if needed. For example, a clinical examination reveals a taut band of muscle in the trapezius that refers pain to the angle of the mandible upon palpation. If the rest of the exam is noncontributory, there is no justification for advanced imaging. The exception to this is a panoramic radiograph, which is a useful tool to screen for gross abnormalities.
One suggestion for those studying and treating TMD and orofacial pain is to examine all the structures of the body that fall within the confines of the trigeminal thalamic tract, or TTT. Anatomical studies have shown that cervical nerves as caudal as C7 can project to the subnucleus caudalis via the TTT.3,4 Clinically, this means that we should be examining the neck, the shoulders and the upper back.
Another frequently ignored phenomenon is pain referral.5 An auriculotemporal nerve block can readily help distinguish between intracapsular and muscular sources of pain, and differentiate pain source versus pain site. However, neither this study nor the Research Diagnostic Criteria for the study of TMD takes these two clinically relevant factors into account.6
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