Getting to the bottom of jaw or muscle pain is about putting together the pieces of a puzzle, which is made of the signs, symptoms and diagnostic findings. During a pre-clinical interview with a new patient today he shared that he has pain over his right joint sometimes when eating. Noting this I began to wonder what I might find as I did my exam to narrow down the possible conditions that can cause true jaw pain during function, or muscle pain that is being referred over the lateral pole of the joint. During his comprehensive exam the patient reported a similar discomfort in his right joint when moving to the left. We discovered this as I had him move to the left to measure range of motion. Both the exam finding and his report of discomfort could be caused by muscle, in particular the Lateral Pterygoid, which refers pain directly over the joint. They could also be coming from retrodiscal tissues that are being loaded in the joint space during translation and initiating the pain response. Being able to differentiate between them is a critical piece of the diagnosis and subsequent treatment recommendations.
The steps are as follows:
- Have the patient bite their teeth together
- Cradle their mandible with both hands applying upward force the patient can work against.
- Ask the patient to attempt the movement that caused the discomfort, without actually moving their lower jaw.
When the patient attempts to move their mandible against the pressure of your hands, the lateral pterygoid will automatically fire. On the other hand, the condyle disc assembly is stable as it is not moving through rotation and translation with the mandible stationary. Given this we can now isolate the cause of the discomfort. During a stabilization test if the pain is present, then we know the cause is the lateral pterygoid firing. If the test results in no pain, we can now identify that it is coming from the change in the condyle disc assembly during actual movement.These findings overlay what I learn about the location of the disc from palpable joint sounds, patient history and joint auscultation.
For my patient we were able to complete a stabilization test and quickly identify that the pain happened even though his mandible was not moving. This focused my attention to the lateral pterygoid muscle as the cause of his discomfort. This information when combined with the rest of the information we gathered during his exam and history helps me determine the most appropriate style of appliance and understand the amount of functional risk .