I’ve written many times on this blog about my belief that occlusion is one of the potential causes of TMD symptoms. An occluso-muscle disorder is one in which the relationship between upper and lower teeth trigger certain muscles of mastication to become active when they are supposed to be inactive, thus causing fatigue. This disharmony begins with mild muscle soreness and can lead to nastier symptoms like severe pain and locking.
Fortunately, we can put an end to this process if we apply the principles of occlusion. Here’s a link to a quick refresher on what posterior occlusion should look like following the cup-fossa philosophy. Okay, with that in mind, let’s meet our patient:
Mrs. Jones is a middle-aged woman complaining of intermittent “deep muscle pain,” occasional tinnitus, and limited opening that has been present for three months. The exam reveals…
Negative history for trauma
If a patient recently was in a car accident and the airbag hit their jaw, then that would totally change the picture. Why else would a woman with no history of TMD suddenly have issues? Could there have been a traumatic incident that she cannot recall?
Approximately 35mm of opening without discomfort
35mm is a little on the small side but still within the range of normal. But notice that I said “without discomfort.” She actually can open closer to 50mm, but she starts to feels a little sore. There is a difference between a true limited opening and an opening that is uncomfortable. The point at which she can not physically open her jaw any further is her maximum opening. The 35mm mark in this case is more of her “comfortable opening.” So I’m not super concerned about this finding.
Pain to resistance during protrusion
I palpate a few muscles of mastication during my exam. One of the most commonly affected is the inferior lateral pterygoid. It is the major player in opening motions and should be at rest during closing. However if there is an occlusal interference during closing, this guy has to become active to aid in a side-shift of the mandible. So the muscle works during opening AND closing and never gets a break. The inferior lateral pterygoid is best tested by having the patient go into protrusive and providing light resistance with your hand.
Significant dental history
I always ask if the patient had any dental work done around the time the symptoms started. There wasn’t any dentistry done, however she did mention that she once had a “sore jaw” and a prior dentist had made her a lower night guard. She started wearing this thing after some mild symptoms returned and now its getting worse. Let’s take a look at the night guard:
Oh no! It’s a soft night guard! I hate these things. I firmly believe that soft night guards should never be used to treat TMD. Their use is controversial and I have never found conclusive studies, but my anecdotal experience is that they can actually make the problem worse. I advised the patient to stop wearing the appliance.
The patient noted the first point of contact was on the right and a mandibular slide to the left. Here’a photo:
Note the premature contacts on the lingual slopes of the buccal cusps. These teeth are slightly rotated (especially # 5), which can make these slopes more likely to interfere.
We adjusted the two premature contacts, advised her to discontinue the use of the soft night guard, and scheduled a follow up visit 1 week later. The patient stated she noticed a “more balanced bite” immediately after the adjustment. The muscle soreness began to fade within a few days. At the follow up visit we re-examined her. She was able to open more comfortably and there was diminished soreness when giving resistance to protrusion.
If you’d like to dig deeper into the world of occlusion and hone your skills, check out this e-book I wrote on the TMJ and occlusal adjustment.