What is TMJ?
The Temporomandibular joint (TMJ) is possibly the least understood joint in the body. A broad variety of presentations ranging from pain, lack of opening, clicking, clenching, grinding, locking or even headaches get lumped into a “you have TMJ” diagnosis. This equates to going to a dentist with a toothache and getting the diagnosis of “you have a tooth,” it is merely pointing out which structure is sore.
The jaw joint is complex. It takes all the best bits of all the other joints in the body and puts them all together in one. The linking table highlights the unique factors a clinician needs to consider when assessing TMJ pain and dysfunction.
At The Headache, Neck & Jaw Clinic, our physiotherapists consider the biomechanics of the jaw to take the guesswork out of what structures are restricted and sore and what is actually causing the dysfunction. Our expertise and clinical focus on a TMJ caseload allows us to identify the individual ligaments, muscles or nerves that are at fault to provide an accurate diagnosis, from which we can implement a precise treatment plan with expectations of timeframes and outcomes.
For example: a painful deviation at 30mm of opening indicates shortening of the Oblique fibres of the lateral collateral ligaments. This is treated by localised stretching in clinic and at home and should see gradual resolution of length over a 4 to 6 week period. If no change is seen, other structures such as the disc are considered or a referral to a dentist/prosthodontist to assess occlusion is actioned
Data we collect on jaw treatment (see next paragraph) is used as a reference to allow us to know exactly how well a condition is progressing over time to justify further treatment or onward referral.
Let's Get Scientific
If you do a literature search on TMJ pain, you will realise how under-researched the field really is (especially when you put physiotherapy in your search). The Headache, Neck & Jaw Clinic values Research Based Practice, and view contribution to the medical database as a priority. We conducted a retrospective internal review of our practice as follows.
Using depression range of motion as a primary outcome measure, we reviewed 52 consecutive patients. On average, our patients initial opening range was 31.6mm. Patients were remeasured before subsequent treatments using calipers (capable our measuring to 1/10 of a mm) for up to 6 treatments. Our results show that after 6 weeks of treatment, on average, patients gained 12.8mm of opening.
Our goal is to restore 45mm of depression which is considered normal range of motion. Our patients achieve on average 44.4mm of opening after 6 weeks. Based on this data, we are confident that our physiotherapists can achieve a functional improvement for our patients when using range of motion as an outcome measure. We are also trialling methods of measuring improvement in jaw pain.
Is physiotherapy the only thing that helps jaw pain?
No. Ideal TMJ dysfunction management involves a multidisciplinary team including Dentists, Prosthodontists, Physiotherapists, GPs, Maxillofacial surgeons and even Psychologists. One of the hardest parts about treating “TMJ” is knowing your limitations of what you can achieve with treatment and when to refer on.
It is hard to know who to refer to as first choice treatment for TMJ pain and dysfunction. The linking table lists the recommended treatment pathways, and you will be surprised to see that physiotherapy isn’t the answer to every problem.
What is a click?
A click is a loss of congruency with the condyle of the jaw and the disc. Instead of having a smooth movement, the condyle sticks behind the disc and then jumps forward quickly making a joint sound. Not all clicks require intervention, but definitely require a referral to a physiotherapist if the click is getting louder or more painful. Clicking jaws progress to locked jaws.
What is a locked jaw?
A locked jaw is when the disc dislocates anteriorly and forms a mechanical block to stop the condyle translating (sliding forward). No translation means the jaw can’t open past 25mm, and any closed lock requires immediate referral to a Physiotherapist and Oral Surgeon.
What causes a deviation/ deflection?
As the jaw opens, both condyles rotate through Phase 1 and then translate through Phase 2. If there is an internal derangement in for example the R disc, the 2 jaws will translate forward at different times; the uninhibited L jaw will slide further and the R jaw will stay put. A deviation to the right is observed on a R internal derangement. On closer examination, shortening in the length of the collateral ligaments will commonly lead to a change in the congruency of the disc.
To further confuse the issue, the overcompensating left jaw that is working hard to keep the jaw functioning is quite often the one that becomes painful from the muscular parafunction.
Can physiotherapy fix nocturnal clenching and grinding?
No. Physiotherapy can alleviate the secondary complications associated with nocturnal grinding but splint therapy from a Dentist or Prosthodontist and medication is generally the best choice. Physiotherapy can help with daytime clenching by highlighting bad postural habits and changing the muscle memories that cause them.
What causes pain when there is no restriction?
The jaw, ear and temple are common areas of referred pain from local muscles, such as the Masseter, Pterygoids or Sternocleidomastoid, but given the complex neural pathways that converge with the cervical spine nerves in the Trigeminocervical nucleus, it is more likely that the origin of pain without restriction is the cervical spine.
What is normal posture of the jaw?
To be able to restore normal TMJ function, the clinician must have clear knowledge of what normal actually is.
• 45 to 55mm of straight line opening with minimal joint sounds or deviations.
• 10mm laterally deviation left and right
• You should be able to put your tongue on the roof of your mouth and open and close or move your jaw side to side without the tongue moving off the roof.
• Through-range control of isolated pterygoid muscles on strength testing
• No head tilting or chin poking when you open your jaw.
Normal posture is the first step to recovering function in any TMJ condition from trauma to derangements or bruxing. Normal posture can be reinforced from all health professionals that manage TMJ conditions and is as follows. Tip of the Tongue on the roof of the mouth (“N for no” position), teeth slightly apart, lips together and breathing through the nose. This minimises parafunction and can be used as a cognitive tool to break bad oral habits that reinforce jaw pain.
Case study 1
51yo female presents pain on opening in her R TMJ after a prolonged dental appointment 4 weeks ago. It has not resolved with nsaids and rest and is progressing to cause R sided neck ache.
On examination, she had 37mm of opening with a deviation to the R at 22mm of opening. She was tender to palpate in her R masseter muscle and R sub occipital muscles. On closer examination, she had scalloped indentations around the edge of her tongue and couldn’t differentiate left and right tongue and jaw movements.
Diagnosis: strained Oblique fibres of lateral collateral ligament (source of pain)
20mm of depression is the transition from rotation to translation which is controlled by the oblique fibres of the lateral collateral ligament. This ligament would be tight and stiff on isolated stress testing and by isolating and stretching it, we should see both an improvement in her pain and the quantity of her range, ie. 40+mm. This will increase right forward translation which will reduce the deflection to the right and in turn reduce the need for her upper neck (extension) to help out with jaw opening.
Improved slide and glide will clear her pain, but won’t necessarily fix the problem. From her examination, she had long term signs of poor proprioceptive awareness of her jaw muscles and signs of long term weakness (tongue thrusting resulting in scallop marks). To completely resolve her symptoms and restore normal function, we must consider what long term muscle failures she may have which led to a simple extraction causing so much trouble. We need to assess the strength and control of her hyoid muscles, tongue muscles and upper cervical spine muscles. We need to demonstrate what compensatory cheats she has, educate her into “good habits” to improve the stability of the jaw to ensure that this doesn’t happen again next time she visits the dentist, who probably didn’t do anything wrong during his procedure, but got the blame for 10 years+ of bad habits.