Temporomandibular Disorders (TMD) is an umbrella term that includes disorders of the temporomandibular joint (i.e., jaw joints) and its associated anatomical structures. TMDs can be intra-articular (i.e., within the joint) or extra-articular (i.e., outside the joint). There is also a strong correlation between cervical spine postural dysfunction and TMD. There are many conditions that cause temporomandibular joint (TMJ) pain. It is important to make an accurate diagnosis to ensure that the best management is administered and that potentially serious problems are not overlooked.
Causes of Temporomandibular Disorders
1. Inflammatory conditions. Caused by direct trauma, such as a blow to the chin or jaw, indirect trauma, such as a whiplash associated disorder (WAD), heavy chewing, grinding (i.e., bruxism), clenching of the jaw or loss of dental height due to worn down or missing teeth.
- Synovitis. The synovium or the capsule of the TMJ may be inflamed. There is often pain at rest and limited range of movement, or pain at the end of range.
- Retrodiscitis. The retrodiscal tissue (i.e., the posterior attachment of the articular disc to the mandibular fossa) is highly vascular and innervated by nerve endings, and if inflamed can cause severe pain. The jaw may deviate away from the painful side at rest and with opening.
2. Internal derangement. Refers to structural changes to the TMJ and can be caused by direct trauma, such as a blow to the jaw or falling on the chin, indirect trauma, such as a WAD, long-term clenching or grinding, heavy or hard chewing or prolonged periods of mouth opening, such as a dental procedure or a general anaesthetic.
- Disc displacement with reduction. The articular disc within the TMJ can become displaced in any direction, but anterior displacement is most common. The disc will be pushed forward during opening and will bunch up. At a certain point within opening/closing the jaw, the disc will reposition or reduce itself causing an audible or palpable click. The jaw will often deviate towards the affected/restricted side.
- Disc displacement without reduction. This is a more severe version in which the disc will not reduce causing pain and a loss of range. This is called a closed lock. The jaw will often deviate towards the affected/restricted side. There will be no click but the patient may report that there was a click at the time when their jaw locked.
- Degenerative arthritis. Is age-related and is often seen on plain x-ray as a flattening of the surface of the TMJ and bone spurs. Crepitus (i.e., the cracking/clicking/popping sounds with joint movement) can often be felt or heard.
- Inflammatory joint diseases. Autoimmune conditions (i.e., body attacks self) such as rheumatoid arthritis, ankylosing spondylitis, infectious arthritis, reactive arthritis and gout.
4. Hypermobility. Refers to abnormally increased joint movement, which can result in excessive anterior movement of the jaw and the articular disc. This causes deviation of the jaw away from the affected side. Clicking sounds in the TMJ and pain may be experienced. Hypermobility may be related to connective tissue disorders such as Marfan syndrome or conditions such as Down’s syndrome and cerebral palsy. Long-term hypermobility can cause the articular disc to stretch and degenerate. The disc can then fail to reduce on closing, causing the TMJ to become stuck in an open position (i.e., open lock).
1. Muscle Spasm. Causes pain and limited jaw movement. This is referred to as trismus. It often affects one or more muscles, commonly the muscles of mastication (i.e., chewing), especially masseter, temporalis and the pterygoid muscles. Causes include prolonged dental procedures or anaesthetics where the mouth has been held open for extended periods of time, stress, bruxism and postural dysfunction.
2. Cervical Postural Disorders. Muscles that run from the chin to the hyoid bone in the neck cause posterior forces on the jaw when the head is protracted forward. Prolonged neck protraction can lead to poor posture and stress-related posture on the jaw, which pushes back on the tissue adjacent to the TMJ disc, eventually causing swelling, pain and gradual degeneration of the disc.
3. Temporal Tendonopathy. Caused by excessive contraction of the temporalis muscle usually as a result of bruxism. There is tenderness and swelling of the front part of the temporalis tendon.
4. Fractures of the Mandible. Usually fractures will occur in the mandible together with a fracture/dislocation of the TMJ condyles. Treatment can usually begin within a week or two of surgery to begin early mobilisation of the TMJ and to restore function.
Conservative Management of Temporomandibular Disorders
TMD can be a recurring conditions, but patients can self-manage effectively and symptoms may not progress. Research has shown that conservative management should be trialled first in cases of TMD.
Treatment in the acute stage
Conservative management would need to address the symptoms identified in the assessment, but initially involves reducing pain, swelling and muscle spasm. When the pain and swelling is managed, treatment may include soft tissue releases and TMJ mobilisation techniques.
Treating the neck
It is also important to treat any associated neck pain and headaches. Neck posture correction and self-management techniques of the neck and jaw such as range of motion and neck strengthening exercises and self-mobilisations of the jaw are important. The aim is to improve coordination, stability and alignment of the TMJ and neck.
If the patient has signs of sleep bruxism then they should discuss this with their dentist and whether an occlusal splint would be appropriate for them. Occlusal splints hold the TMJ slightly apart as the patient clenches or grinds, preventing compression of the TMJ. This can help to relax jaw muscles and reduce swelling and inflammation. There is some evidence to supporting the use of splints to reduce long term degeneration of the TMJ, disc and teeth. Other dental problems, such as cavities, that are causing pain or uneven chewing, lack of dental height or missing teeth may also need to be addressed.
Self-management strategies to improve sleep habits including sleeping positions, stress management and diet modification should also be addressed.
With appropriate conservative management, most patients will see a significant improvement in their symptoms within 3-6 weeks. The chiropractors at Sydney Spine & Sports Centre (S3C) provide the best, evidence-based practice with a focus on self-management in patients with TMD.
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