Temporomandibular disorder (TMD) is a problem affecting the 'chewing' muscles and the joints between the lower jaw and the base of the skull.
Doctors sometimes refer to the condition as "myofascial pain disorder".
It's been estimated that up to 30% of adults will experience TMD at some point in their lives.
The condition itself isn't usually serious, and the symptoms it can cause – including pain, jaw joint clicking or popping, and difficulties eating – usually only last a few months before getting better.
However, these symptoms can significantly lower quality of life, and specialist treatment might be required if they're severe.
What are the symptoms?
TMD can cause:
clicking, popping or grating noises as you chew or move your mouth
muscle pain around the jaw
pain in front of the ear that may spread to the cheek, ear and temple
difficulty opening the mouth – the jaw may feel tight, as if it is stuck, making eating difficult
headache or migraine
earache or a "buzzing" or blocked sensation in the ear
pain in other areas of the body – such as neckache or backache
These symptoms may lead to related symptoms, such as disturbed sleep.
What are the causes?
Possible causes of TMD include:
clenching your jaw or grinding your teeth during sleep (bruxism) – which overworks the jaw muscles and puts pressure on the joint (often caused by stress)
wear and tear of the inside of the jaw joint – usually caused byosteoarthritis
injury to the jaw joint – for example, after a blow to the face or surgery
stress – some people may inherit increased sensitivity to pain or stress
uneven bite – for example, when new fillings, dental crowns or dentures are fitted
specific diseases – TMD may be associated with specific diseases such as rheumatoid arthritis, gout or fibromyalgia
However, some people may develop TMD without an obvious cause being found.
How is TMD treated?
If you have TMD, see your GP or dentist first for diagnosis and to discuss treatment options.
Generally, non-surgical treatments such as lifestyle changes and self-help physiotherapy-type treatments are tried first.
A small number of people with severe TMD may be referred to an oral and maxillofacial surgeon to discuss further treatment options.
There are a number of self-help measures that can help improve TMD, including:
resting the joint by eating soft food and avoiding chewing gum
holding a warm or cold flannel to the jaw for 10-20 minutes, several times a day
doing a few gentle jaw-stretching exercises – your healthcare professional can recommend appropriate exercises
avoiding opening the joint too wide until the pain settles
avoiding clenching the teeth for long periods of time
massaging the muscles around the joint
relaxation techniques to relieve stress
not resting your chin on your hand
Mouth guards (plastic devices that fit over your teeth) may be helpful if you grind your teeth.
These cover the teeth at night to reduce jaw clenching and teeth grinding, and can be made to measure by your dentist.
Painkillers such as paracetamol, ibuprofen or codeine can help relieve the pain associated with TMD.
If these aren't enough to control the pain, your doctor may prescribe stronger medication such as a muscle relaxant or antidepressant.
If TMD is caused by a disease such as arthritis, a steroid injection into the jaw joint can help reduce pain and swelling in a joint or the surrounding soft tissue.
Most people report feeling less pain within the first 24 hours to one week.
You may find your pain improves for a period of a few weeks to several months and, in some cases, the injection resolves the pain completely.
If the above measures don't help and the source of your symptoms is the temporomandibular joint – rather than the chewing muscles – your specialist may suggest a surgical treatment such as arthrocentesis (joint wash-out).
Open joint surgery may be considered in the rare cases where there is an abnormality within the joint.
Total joint replacement may be recommended for an extremely small number of people with severe, long-lasting symptoms and impaired jaw function. The National Institute for Health and Care Excellence (NICE) has produced guidelines on this procedure.
All joint surgery can have significant side effects and you should discuss these with your surgeon.
Most cases of TMD improve over time and do not get worse, and most people will not need surgery.
In the meantime, symptoms can often be improved with the treatments mentioned above.