Chewing muscle pain: the muscle or the jaw joint?

When you clench your teeth, you can feel with your fingers a muscle that hardens in two places: the masseter in the cheek, just above the angle of the lower jaw, and the temporalis in the temple. These muscles produce the force of chewing. NIDCR lists pain in the chewing muscles and the jaw joint as the most common symptom of TMD; it writes that TMD affects about 5 percent of adults in the US and is twice as common in women as in men, especially in women aged 35–44.

There is usually more than one cause of muscle pain. The NHS lists among the causes of TMD teeth grinding, wear of the joint, a blow to the head or face, stress and an uneven bite. NIDCR, on the other hand, writes that in most people the exact cause is not known, that research suggests genes, psychological and life stress and how a person perceives pain play a part together, and that it does not support the belief that a bad bite or braces cause TMD. Clenching your teeth during the day without realising it, chewing gum and biting your nails also put extra load on the muscle.

The criteria used internationally to diagnose jaw joint and muscle problems (DC/TMD) separate muscle pain from joint pain by examination. The doctor presses on the masseter and temporalis with a pressure of about 1 kilogram for 2 seconds and asks you to open your mouth; at the same time, they ask whether the pain that comes is the familiar pain you have been having. For a diagnosis, the criteria require the patient's familiar pain to be reproduced by jaw movement or pressure. The accuracy of the muscle pain criterion was found to be high in research: it picked up 90 percent of people with muscle pain and correctly ruled it out in 99 percent of those without.

The same criteria divide muscle pain into three. If the pain stays only at the point being pressed, it is called local myalgia; if it spreads within the boundaries of the muscle, myofascial pain; and if it is referred somewhere outside the muscle, myofascial pain with referral. For this distinction, the doctor holds the pressure for 5 seconds. DC/TMD writes that referred pain is important at least for differential diagnosis, and that pain referred to the teeth that eventually turns out to come from the muscles also falls into this group.

Pain referred from a muscle to a tooth is a real trap. In a case published from India, the source of pain felt in a lower right tooth was the masseter muscle on the opposite side; the correct diagnosis was made with a detailed history, a head and neck examination and a diagnostic injection into the trigger point in the muscle, and unnecessary dental work was avoided. A study of 20 women with jaw muscle pain in Spain also found that the points in the temple and jaw muscles that brought on the patient's familiar pain when pressed (active trigger points) referred pain to the mouth and face.

One way to roughly tell muscle from joint at home is to look at where the pain is. Masseter pain is felt in the cheek, above the angle of the lower jaw; temporalis pain is felt in the temple. Joint pain, on the other hand, is just in front of the ear canal, at the point where you feel movement when you put your finger there and open and close your mouth. Clicking, popping or locking points more to the joint. NIDCR writes that painless clicking and popping are common, considered normal and need no treatment. Muscle and joint pain are also often seen together.

You also need to know that familiar pain does not always mean muscle pain. DC/TMD stresses that infection and rheumatic diseases affecting the jaw joint can also cause familiar pain with movement or pressure, so the criteria should be used as part of a broader clinical assessment. The NHS also asks for an urgent doctor's appointment if there is tenderness in the temple or scalp and problems with vision along with jaw pain; these signs can point to a blood vessel disease such as temporal arteritis.

The course is usually good. The NHS writes that TMD is usually not serious and often gets better on its own. NIDCR states that most TMDs are short-lived while some can become long-term, and that TMD can be seen together with other painful conditions such as headache, back pain, sleep problems and fibromyalgia. The DC/TMD classification also lists chewing muscle pain linked to fibromyalgia and widespread pain as a separate group; if there is pain elsewhere in the body too, the treatment plan changes accordingly.

The first list is signs that make it more likely the pain is coming from the chewing muscles. The second list is signs that point to the joint, a tooth or a situation that should not wait. The examination makes the distinction; these lists are so that you take the right information to the doctor.

The sequence first sorts out the situations that should not wait, then moves on to telling muscle from joint and to reversible treatments.

1. 1

   First, emergency signs

   If there is swelling around the eye or in the neck, swelling that makes it hard to breathe, swallow or speak, or sudden loss of vision, call 112. If you cannot open your mouth or eat and drink, or there is tenderness in the temple and a visual symptom, see a doctor the same day.

2. 2

   History

   You are asked where the pain is, what makes it worse, whether it is worse in the morning or the evening, about clenching and gum-chewing habits, stress, sleep and whether there is pain elsewhere. DC/TMD counts whether the pain changes with jaw movement, chewing or clenching habits as part of the diagnosis.

3. 3

   Muscle and joint examination

   The doctor presses on the masseter and temporalis with a standard pressure, feels around the joint, measures how wide your mouth opens and asks where the familiar pain is coming from. The pressure is held for a few seconds to see whether the pain spreads.

4. 4

   Ruling out the teeth

   If the pain also spreads to the teeth, the dentist assesses the teeth with cold, tapping and bite tests and X-rays. If no tooth reproduces the pain, no procedure that cannot be reversed is done on a tooth.

5. 5

   Self-care and information

   In a meta-analysis combining 47 randomised trials, explaining the condition to the patient and teaching self-care gave similar results to many other conservative treatments in the medium and long term; other treatments were able to reduce pain more in the short term. The certainty of the evidence was low or very low.

6. 6

   Jaw exercises

   The 2023 guideline of the Japanese Society for Temporomandibular Joint recommends mouth-opening exercises done by the person themselves and hard stabilisation splints as primary treatment; the level of evidence was rated as very low. In a systematic review examining 5 studies, coordination exercises that teach the jaw to open and close smoothly showed significant improvement in pain and range of movement. Learn the exercises from a dentist or a physiotherapist.

7. 7

   Further steps if it does not go away

   The NHS writes that your GP can give stronger painkillers, relaxation techniques and sleep advice, can refer you to a dentist, a psychologist or a physiotherapist if needed, and that if these do not help, a joint specialist can consider painkilling injections or surgery.

Because the evidence is limited, NIDCR recommends protective and reversible treatments first, and avoiding treatments that permanently change the teeth, the bite or the joint and those that involve surgery.

Below are the wrong decisions often seen with this picture, and what they cost.

The NHS writes that TMD often gets better on its own, while NIDCR writes that some cases can become long-term. The sequence below is a general framework; the plan of the doctor who follows you up comes first.

1. The first days

   Soft foods, painkillers, applying ice or heat and gently massaging the muscles. Stay away from chewing gum and hard foods, and take care to keep your teeth apart during the day.

2. The first weeks

   If the pain is easing, keep up the self-care. Try to notice the clenching habit; if needed, the dentist teaches you exercises or takes an impression for a night guard.

3. If it is still there after a few weeks

   Your dentist or GP reassesses you; physiotherapy, psychological support or a pain specialist may become involved.

4. Long-term pain

   If the pain lasts for months and spreads to other areas, an assessment by an orofacial pain specialist is appropriate. Get a second opinion before treatments that cannot be reversed.

We do not give a single figure here, because treatment for chewing muscle pain usually stays limited to simple measures, but sometimes needs several specialists. These are the items that determine the scope:

Examination and tests

In addition to the muscle and joint examination, an X-ray may be needed to rule out the teeth.

Night guard

A guard made from an impression and the follow-up appointments are a separate item.

Physiotherapy or psychological support

The number of sessions is set according to the course of the pain.

How long the pain lasts

With long-term and widespread pain, follow-up by a pain specialist widens the scope.