The Appliance as a Diagnostic Tool

The oral orthotic appliance has almost as many uses as a diagnostic aid and for treatment as it has names – splint, bite splint, guard, night guard, piece of plastic, acrylic thing, drawer space holder, bathroom counter ornament, etc.

We can use them to protect teeth at night, create a temporary physiologic occlusion to test or confirm comfort, or identify difficult areas to re-contour/equilibrate do to lack of adequate tooth morphology to name a few. (Figs. 1-2)

Appliances and Joint or Muscle Pain

Recently in a SpearTalk thread discussing diagnosis of joint or muscle pain, the topic of using a full-coverage appliance for TMD diagnosis came up. You may remember that the teeth and joints form a class III lever system. Posterior contacts close to the joint (lever) support the joint, decreasing the load; anterior contacts farthest away from the joint (lever), load the joint, almost isolating the pressure to the joint.



When we build and equilibrate an appliance (pre-insertion in the lab), we have the option to increase or decrease the area that we are loading by placing contacts on the anterior, posterior or both. (Figs 3-4)

We can even create an environment with slightly lighter pressure on the posterior teeth; taking the second molars out of occlusion to move some forces farther from the lever, if we want. By doing so, we can start our diagnostic evaluation intentionally, from the day we deliver the appliance.

If we leave our contacts on anterior teeth to load the joint and the pain decreases, our diagnosis begins to lean towards an origin of muscle. If we leave our contacts on posterior teeth – like a posterior pivot or aqualizer – and the pain decreases, our diagnosis begins to lean towards that of joint origin. Similarly, if we load the joint with anterior contacts and the pain becomes significantly worse over time, our diagnosis also begins to lean towards an origin of the TMJ.

Almost equally as important, if not more, this thought process forces us to determine why we are making the appliance and what we expect or hope to see – before we even construct it! Imagine that.



When we are adjusting the appliance, we can remove contacts on back teeth if we want to create an anterior bite plane in an attempt to deprogram the lateral pterygoid. But again, if pain increases, we can quickly remove some of the anterior contacts to pick up some posterior support and evaluate the pain or discomfort with increased joint support. Knowing this might be needed ahead of time also allows us to consider how thick the applicance should be – anticipating this option for a diagnostic process when appropriate.

So, as opposed to just adjusting for even and simultaneous contact, you might consider using the intensity and location of dots and stripes to help diagnose and find individual comfort for your patients.


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