TMJ and Jaw Resources for Patients
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What is the TMJ?
The TMJ or temporomandibular joint is a ginglymoarthrodial joint, meaning it acts both like a hinge and a sliding joint. A hinge joint acts like a door, allowing one plane of movement and a sliding joint is when two (almost) flat surfaces meet and can allow movement in any direction.
The TMJ is the most used joint in the entire body and is surrounded by a strong muscular and passive support system.
Jaw Resting Position
The neutral jaw resting position, or good posture for your jaw is lightly placing the tip of the tongue to the roof of your mouth behind your front teeth like you are making the ‘N’ sound. Now position your teeth to have a slight gap softly bring your lips together. This position allows the muscles of the jaw to be relaxed at rest, negates the ability to clench as there is a gap in between your teeth and forces nasal breathing.
The opening of the jaw occurs in two ‘compartments’ of the joint. Initially when the jaw begins to open pure rotation of the head of the jaw on the disc occurs (hinge part of the joint) and once the head of the jaw has reached its rotational limit, the disc and head of the jaw lock and slide forward (sliding part of the joint). A poor movement pattern can be the result of dysfunction in either or both of the different compartments of movement.
The articular disc is a butterfly-like shaped structure that sits on top of the condyle of the jaw like an ice cap on a mountain and divides the jaw into 2 compartments (mentioned above).
The TMJ is a relatively avascular and aneural structure (which means it has limited blood and neural supply), it is the role of the retrodiscal tissue to supply the TMJ neural and vascularly. The retrodiscal tissue sits posteriorly to the disc in the jaw joint and is not under any compressive load from either the skull or jaw, however when a disc becomes anteriorly displaced compression of the retrodiscal tissue can occur and be a source of pain. Over a period of time, the retrodiscal tissue, if under a compressive load will create a ‘pseudo-disc’ to take the role of the disc that is no longer in its correct position.
Alveolar Bone Density
When excessive force is applied to a sphere, the force is transferred to the centre of the sphere and it will break down from the inside out. Look at the quality, colour and density of the alveolar bone in the head of the condyle and the articular eminence and compare it to the Anteriorly displaced disc with reduction video.
On X-ray, a jaw joint under sustained compression will not necessarily show up as degeneration as you don’t see changes to the joint surface until the alveolar bone has collapsed.
Author: Nigel Smith
Jaw Resting Position
The resting position of a jaw that commonly clicks is further back and up than compared to a jaw that doesn't click. This change in resting position puts an increase in compression of the disc due to the passive structure being in different positions and creating different areas of pressure. The disc response to compression is to displace forward, altering the normal movement pattern for the jaw.
The altered pattern of movement will involve a click during the opening and closing of the jaw, this may be accompanied by an obvious deflection or deviation of the jaw to one side during movement. The click that you hear or feel on open is the jaw relocating to its correct position on the disc and the click on close is the jaw slipping off the back of the disc and into its altered resting position.
When the disc is anteriorly displaced the jaw loses its ability to differentiate movement into certain compartments. Generally, the jaw will increase the rotation aspect of the movement, compressing the posterior joint capsule before reducing the displaced disc.
As mentioned before, in a normal jaw the retrodiscal tissue will sit posteriorly to the disc, free of compression. When a disc becomes anteriorly displaced the retrodiscal tissue will sit in the middle of the joint and succumb to compressive forces during normal jaw functions like chewing or biting. This is a common source of pain in the jaw or even referring to the ear.
When the condyle (top of the jaw bone) reduces back onto the disc the condyle can still move and translate a long way forward, in some cases of a clicky jaw the range of opening of the jaw will remain unchanged due to this. In some cases, the range can be lessened or the opening can become painful due to the structures bearing weight on the retrodiscal tissue. It is important to assess a clicking jaw as each clicky jaw has its own changing properties and will be slightly different.
Author: Nigel Smith
Jaw Pain Assessed
Was your Jaw Pain properly assessed?
Traditionally, all pain and restriction in the jaw region, whether it be a clicking jaw, a painful bite, clenching, headaches or even a locked jaw, have all been diagnosed under the one umbrella term, “TMJ”.
The TMJ acronym actually stands for Temporo-Mandibular Joint, the anatomical name of the joint, so to diagnose “TMJ” is similar to you going to the GP after tripping and falling and hurting your lower leg and your GP assessing you and diagnosing you with “Ankle.” It’s merely naming the structure you injured, so a more correct umbrella term should be “Temporo-Mandibular Dysfunction (TMD)”.
Incorporated in this umbrella term, there are 4 major muscle groups, 3 different ligaments, 2 joint surfaces, and an articular disc that can all be the cause of TMD, not to mention the trigeminal nerve. Management of an arthritic joint surface is vastly different from managing a spasming muscle, though their initial presentation can be very similar, meaning the ability to accurately diagnose which of these structures are actually causing the dysfunction/pain, determines the correct course of treatment to resolve the symptoms.
There is no “one size fits all” treatment approach to TMJ management. More importantly, accurate diagnosis will provide clinical evidence as to why and how the structure(s) have become involved, so treatment can be tailored to include medium and long term goals to ensure your problem doesn’t return as soon as you finish treatment.
Consider the advice you may have already been given about your “TMD.”
· What was the actual diagnosis?
· Did your practitioner diagnose you from your description alone without actually assessing you manually?
· What assessment techniques (if any) were used to derive that diagnosis?
· What were your treatment goals set after assessment?
· How were these goals reassessed?
· What was the clinical reasoning behind the treatment that you may already have gone through?
· Did it work?
Most failed treatment occurs because of inappropriate treatment choices due to inaccurate or lazy diagnosis. Just because treatment has failed in the past doesn’t mean you are unfixable, it means you need a better assessment and an appropriate treatment plan. There is no guesswork in treating “TMD”
Author: Nigel Smith
What is a locked jaw?
A locked jaw occurs when the disc/the cartilage that sits behind the jaw joint slides forward and forms a mechanical block, which prevents your jaw from opening. When this occurs, your movement is significantly limited and you are unable to fit more than 2 fingers in your mouth.
Most people who experience a locked jaw have a history of sporadic clicking and when the jaw locks the clicking stops. It is important to note that if the clicking returns this is a good thing as the click itself is the disc/cartilage moving back into place as you overcome the mechanical block it has formed. It is also important to note that not every clicking jaw will become locked. A consistent, pain-free unchanging click that you have had for years is unlikely to become unstable and lock. It is the recent onset clicking, the sporadic clicking or changing click that warrants ongoing investigation.
A locked jaw requires immediate referral to a Physiotherapist with experience in locked jaws and/or referral to an Oral Surgeon in cases where we are unable to relocate the disc.
Author: Nigel Smith
Dislocation refers to the displacement of the temporomandibular joint disc or condylar head within the joint complex. Appropriate treatment resides in individual patient progression post injury, additional trauma and the extent of secondary complications and soft tissue contribution. Cases are typically seen through emergency department, Oral and Maxillofacial surgery, dentist or GP in some cases prior to referral to the clinic. However, in some cases we may also have direct contact without referral. The two typical kinds of dislocation we see include disc displacement without reduction (anterior or posteriorly placed) or condylar displacement secondary to compromised ligamentous integrity.
We typically refer on for further imaging such as Cone beam CT or MRI (preferably) through either specialist or GP for Medicare rebate purposes and a diagnostic baseline. Conservative management is attempted in communication with the associated referrer and if they are unresponsive to conservative management early on, we ensure referral to Oral and Maxillofacial surgery for further assessment and management. We typically expect 45-55 mm of movement in depression ROM (opening availability).
However, the minimum normal range is 40 mm, and limited opening in combination with self-reported restriction on a side that may have previously resolved with a click is often reported by the patient. Typically, there has been a history of intermittent clicking prior to this. Depending on the nature of the dislocation, it may reduce quickly in which case the emphasis is largely on strengthening the stabilizes and maintaining functionality to avoid subsequent displacement. More restricted closed lock conditions or chronic displacement often require more intensive capsular de-loading to release the posterior capsule and support reduction of the disc. This is accompanied with motor control exercises, pterygoid strengthening and postural retraining to encourage movement patterns, head positioning and a jaw posture.
On initial assessment we expect ipsilateral condylar translation limitation due to blocking of the disc, and the contralateral condyle translating past the point of blocking. This limitation is felt quite clearly through palpation of the joint on that side. From a rehab perspective it is therefore critical to reinforce midline translation to avoid secondary capsular restriction, spasming and hyper-translation of the contralateral joint as a result of altered movement patterning.
Author: Nigel Smith
Fractured Jaws explained
Motor vehicle accidents, sporting injuries and assaults are all common causes of jaw fractures. Jaw fractures are usually diagnosed at hospital with either an x-ray or CT scan. Depending on the type and location of fracture you will either require surgery or a period of immobility. During this period of immobility you will be required to go on a soft/liquid diet, avoid excessive jaw movements with brushing and speaking and you may also require splint therapy. During this time Physiotherapist treatment will primarily focus on your upper neck, which is commonly a secondary source of pain following jaw trauma and plays a large role in the posture, positioning and function of your jaw.
Once your fracture has healed, your Physiotherapist will begin to mobilise and stretch your jaw joint to assist in regaining your opening range and jaw function. During this period you will also be required to do some exercises at home to regain the strength, control and coordination of your jaw muscles.
Author: Nigel Smith
Clenching or Grinding Jaw
Do you suffer from Clenching or Grinding?
Bruxism is the term used to describe habitual clenching or grinding of the teeth and is a sign of oral para-function. Factors that contribute to the prevalence of bruxing include stress, anxiety, an abnormal or uncomfortable bite which is common in those suffering from sleep apnoea with 70% also complaining of bruxing.
Night bruxing may be identified by a partner or family member who can see or hear when you grind at night or, by a dentist who can identify physical signs such as excessive wearing of the teeth and scalloping of the tongue. Other signs of night bruxing include a dull headache and jaw tenderness first thing in the morning, as well as catching yourself with your teeth tightly closed at night.
The normal resting jaw posture during the day is with your tongue on the roof of the mouth, teeth apart, lips together, breathing through the nose. Day bruxing occurs when you find yourself resting with your teeth pressed firmly together. Treatment of bruxism commonly involves splint therapy to unload the jaw during the night and to protect your teeth from further damage. Physiotherapy is most effective for day bruxism and typically requires retraining of the postural muscles of your neck and jaw.
Author: Nigel Smith
Headache, Neck & Jaw Conditions We Treat
Our Brisbane clinics specialise in the treatment of head, neck and jaw conditions, many of which are notoriously difficult to treat. If you’re experiencing symptoms of any of the following problems, our team has the expertise and training to help.
Jaw and Orofacial Pain
Neck Pain and Trauma
Whiplash and Nerve Pain
Vertigo & Dizziness
Singing / Vocal
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