Is Occlusion A Primary Cause of TMD?

By Karen McCloy, DDS

Occlusion is the act of the teeth coming together.


A primary cause is a factor that if present will reliably initiate the pathological changes that lead to tmd in a patient that did not previously have tmd

TMD is a state of chronic pain in the tmj and the soft tissues supporting it. Chronic pain implies the presence of neural plasticity, so we are talking about a state of central sensitization involving the trigeminal nerve. There is no rule that says that tmd patients may not have similar changes in other areas of the central nervous system. Saying that someone has chronic pain does not address it's etiology, and someone with a clicking joint does not have tmd unless they have pain.

If you ask me is occlusion an important pain producing factor in patients with tmd the answer is a definite yes. In normal patients, without plastic changes, occclusal dsiharmony may be nociceptive, but that means it is not pain. Once there are neural changes it becomes pain, a form of allodynia where a nonpainful stimulus causes pain, like when you have a headache and touching your skin or brushing your hair hurts, and controlling it is key to calming down that nervous system.

But our treatment has multiple modes of action, besides occlusion.

It has a placebo effect, becasue we believe, and because of that our patients believe they will improve. Plus the decision to seek treatment also changes someones mindset and makes them more in control

Our orthotics are a form of CBT - cognitive behavioral therapy. We insert them and say lips together teeth apart, and the plastic reminds the patient what the correct oral posture is.

Orthotics provide an occlusal effect, because they provide stable and even point occlusion around the arch.

Orthotics have an orthopedic effect because the realign the mandible to the cranial base and cervical structures.

So we are back to Larry's the chicken or the egg. We only see the pain patients, and in them pain is correlated with occlusion, but that is not the same thing as causation. Our 1st study on nonpain patients showed that most of them had some form of occlusal issue, but they did not have pain. So I think something else has to happen.