Understanding temporomandibular disorders: causes and treatments

Around a third of people in the UK will experience a temporomandibular disorder (TMD) at some point in their life. TMDs affect the two temporomandibular joints (TMJ) that connect your lower jaw to your skull. Pain can originate in the muscles around the TMJ or the bones of the TMJ and can also radiate to other parts of the face and upper body. 

How does your TMJ work?

Your TMJ comprises your lower jaw bone and the base of your skull, with a disc of cartilage sitting in between these bones. The joint is lubricated by synovial fluid that helps reduce friction and allow smooth movement when you move your jaw.

In a healthy TMJ, the lower jaw rotates against the cartilage disc and then, the cartilage disc and lower jaw slide down the base of the skull. Anything that interferes with this process can cause a TMJ disorder.

What are common TMD symptoms?

One of the most common symptoms of a TMD is myofascial pain ie aching or painful muscles on the side of your face, specifically underneath your jaw joint, behind your jaw and/or along your temples (the side of your head behind your eyes). This can cause temple migraines as well as pain in your forehead, neck and shoulder girdle, which includes your shoulder joints, upper arm bone and clavicle.

Myofascial pain is often caused by stress. When you’re stressed, your body releases adrenaline, which tightens up your facial muscles. When these muscles become too tight, their blood supply is temporarily cut off, causing painful cramps and spasms. This can also affect the mechanics of your lower jaw and how your teeth fit together.  

Overly tight muscles can squeeze out the synovial fluid of your TMJ and force the cartilage disc to slip forward. When you then open your jaw, the lower jaw rotates and is then followed by the slipped cartilage disc clicking back into place. This is called internal derangement and causes an audible clicking sound. It occurs in around a third of the UK population. If the only symptom you experience is a clicking sound, you won’t need any treatment. However, if you also experience joint pain, restricted jaw movement or locking of your jaw, it is important to see a maxillofacial surgeon. 

Although the clicking of your cartilage disc during internal derangement doesn’t usually damage your cartilage, it can damage the surrounding soft tissues. These tissues can become inflamed, causing joint pain, usually in front of your ear, which is often mistaken for earache. This pain triggers a vicious circle of muscle spasms and further joint pain. The pain can become so severe that your jaw locks and you can’t open it.

What is the main cause of TMDs?

TMD is often caused by clenching or grinding your teeth, usually without realising you’re doing it, such as while you’re sleeping and specifically during the REM phase of sleep. 

When you’re stressed or anxious, in addition to producing more adrenaline that tightens up your facial muscles, your sleep may be negatively affected with an increase in REM phases. This means there are more opportunities for subconscious jaw clenching. You may, therefore, wake up with a stiff or aching jaw from clenching it overnight. 

Clenching also often occurs when you are in difficult situations eg driving in heavy traffic or in a stressful work meeting. 

What are the risk factors for TMDs?

Stress is the main risk factor for developing a TMD. However, certain situations can increase your likelihood of developing a TMD. This includes a bad jaw injury, such as a heavy blow to your jaw, which can cause muscle spasms, as well as short-term overuse eg during prolonged dental treatment. Holding your mouth open for a long time for dental treatment stretches your jaw muscles and can lead to muscle cramps.

Your risk of developing a TMD also increases if you often chew gum or take certain medications eg the antidepressant and anti-anxiety drug citalopram, which is known to cause muscle tension in the jaw.

Are children at risk of developing a TMD?

Young children may clench and grind their jaws but don’t tend to develop jaw pain. However, people aged between 12 and 20 are more likely to develop jaw pain as a result of a TMD, often due to muscle problems brought on by stress.

How to manage a TMD at home

If you have jaw pain, try resting your jaw by avoiding eating very chewy, sticky or tough foods. If you need dental treatment, ask if it can be performed over several shorter appointments instead of one long one. You can also try gently massaging your jaw muscles and/or applying an over-the-counter anti-inflammatory gel over the joint to help relieve your pain. For more advice on managing a TMD at home, read this patient guide.

When to seek help for a TMD

If your jaw pain persists after two to three weeks of trying the above home remedies, see your dentist. Your dentist can rule out dental causes of your pain, such as wisdom tooth pain. They may recommend you wear a bite splint to reduce overnight clenching or grinding. If a dental cause can’t be found, your dentist can refer you to a maxillofacial surgeon.

Treatment options for TMDs

Only about 10% of people with a TMD need treatment. In most cases when stress is the cause of the TMD, once the stressful situation has passed and the muscles relax, the TMD goes away on its own. 

In those cases where treatment is needed, especially if you have frequent muscle spasms, your maxillofacial surgeon may recommend you see a physiotherapist who specialises in treating the jaw joint.

Your surgeon may also recommend injection of botulinum toxin to ease muscle spasms. This shouldn’t be administered by a general dentist or someone who performs cosmetic botulinum toxin injections but by a doctor trained in using botulinum toxin for the treatment of TMDs. Botulinum toxin needs to be injected into precise locations and if injected into the wrong place can cause weakness in the movement of the corner of your mouth. 

Surgery

If other conservative treatments have not been successful in treating your TMD ie rest, muscle massage, taking anti-inflammatory medication and wearing a bite splint, and you have persistent joint pain, surgery may be appropriate. Persistent joint pain refers to joint pain that is temporarily relieved by having an injection.

In most cases, the initial surgery recommended is an arthroscopy or arthrocentesis.

An arthroscopy is where a thin, telescope-like tube with a light and camera on the end (an arthroscope) is inserted into your jaw via a small cut to see what is going on inside it. This is a more accurate means of diagnosis than an MRI scan. An MRI scan will not provide the information needed to determine if surgery will be effective and should therefore only be used to support a diagnosis.

During an arthroscopy, depending on what your surgeon finds, they may be able to treat your condition by removing inflamed tissue, repositioning a slipped cartilage disc and rinsing out the joint.

An arthrocentesis is a wash out of your TMJ under pressure and can give significant relief of symptoms.

Recovering from a TMJ arthroscopy

Following arthroscopy treatment, around 80% of patients with a TMD get better. Most will get better over the course of six weeks, while around one in 10 will take longer. You will have a small cut in front of your ear, which may be stitched up. In most cases, you can return to work in a week.

Immediately after your arthroscopy, your face will be swollen in front of the ear. Most of the swelling will ease off after a few hours with some residual swelling persisting for a week or so. You will be given facial stretching exercises to get your jaw moving immediately after your surgery and you should continue to perform these daily during your recovery.

One in 10 patients who have treatment during an arthroscopy will initially see an improvement but then have a flare up of pain two to three weeks later. Applying an anti-inflammatory gel is usually enough to resolve this pain. However, if this is not enough, after four to six weeks post-surgery, a steroid injection may be needed.

Throughout your recovery, you should continue to rest your jaw, apply anti-inflammatory gel and wear your bite splint at night. You should gradually return to normal and continue to eat a softer diet until you are free of any TMD symptoms for three months.

For the 20% of patients who don’t improve after arthroscopy treatment, some may need open surgery to address a joint problem. If there is no joint problem identified, ongoing physiotherapy, pain management and conservative management, such as massage and rest, may be needed.