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Temporomandibular Disorder Basics

Temporomandibular Disorder (TMD)

What Are Temporomandibular Disorder (TMD)
Possible Causes
Making A Tough Diagnosis

What Are Temporomandibular Disorder (TMD)

Temporomandibular disorders (TMD) may be one of the most controversial topics in dentistry today. This is because dentists and physicians don't have a clear understanding of what causes it and how to prevent it. There is also disagreement about how it is best treated.

Although it may be surrounded by confusion, TMD is a common ailment. It is estimated that more than 10 million Americans experience TMD symptoms at one time or another. A majority of these people are women between the ages of 20 and 40.

The good news is that for most TMD sufferers, symptoms usually do not mean they have a serious, long-term problem. In fact, with or without treatment, most people get better. Unfortunately, some people experience severe pain and discomfort that lasts for many years.


TMD is not just one specific problem. It is a group of conditions that affect the jaw joint, also known as the temporomandibular joint or TMJ, and/or the muscles that control chewing and moving the jaw.

The TMJ is like a ball and socket. When you open your mouth, the ball, or condyle, moves out of the joint socket. When you close your mouth, the ball slides smoothly
back in place. A soft cushion, or disc, lies between the ball and socket to prevent them from rubbing and to absorb shocks from movements like chewing. Holding all this together are muscles that stretch from the top of the skull to the lower jaw. Usually the muscles that help close the jaw are the ones affected by TMD.

The jaw joint, or TMJ, allows us to open and close our mouths and move our jaws from side to side and backward and forward. As a result, we can talk, yawn, chew and swallow. You can feel your two TMJs by placing fingers on each side of your face in
front of your ears. Now open and close your mouth. You should feel the condyle moving in and out of the socket.

Today, most experts agree that TMD falls into three categories:

  • Problems that affect the muscles in the jaw and neck
  • Problems that affect the bones in the face
  • Problems that affect the bones and cartilage of the face

Some people have TMD that falls into more than one category.


TMD can cause many different types of symptoms. In fact, it often causes symptoms very similar to other diseases and conditions. That's one reason why it can be so difficult for doctors to diagnose.

The most common symptom of TMD is pain or discomfort in the jaw joint or chewing muscles. Other symptoms may include:

  • Popping, clicking or grating noises when the jaw opens and closes
  • The inability to open the mouth very wide
  • Lockjaw
  • Pain in the face, neck and shoulders
  • A tired feeling in the face
  • A sudden uncomfortable bite, as if the upper and lower teeth aren't fitting together the right way
  • Swelling on the side of the face

Some people also experience earaches, toothaches, headaches, ringing in the ears, dizziness and hearing problems.

Possible Causes

Experts are unsure about what causes TMD. However, many think that symptoms can be the result of:

  • Injury to the jaw, chin or TMJ as a result of a car accident, fight or fall. It is also possible to injure the jaw by opening the mouth too wide, like when someone tries to bite into a huge submarine sandwich.
  • Grinding or clenching the teeth, which puts a lot of pressure on the TMJ
  • Dislocation of the soft cushion or disc between the ball and socket
  • Arthritis, such as osteoarthritis or rheumatoid arthritis, which can result from injury
  • Stress, which causes a person to tighten facial and jaw muscles or clench his or her teeth

In some cases, dentists are unable to determine the exact cause of a person's TMD.

Making A Tough Diagnosis

Because the symptoms of TMD often resemble or mimic other conditions and diseases — including migraine headaches and neuralgia — it is difficult to diagnose. To make matters worse, there are no established guidelines for dentists to follow to diagnose these disorders and there is no test that gives a definitive answer.

If your dentist suspects that you have TMD, he or she will go over your dental and medical charts, and will take your medical history, including information about:

  • Your symptoms
  • When symptoms started
  • Whether the symptoms are constant or come and go
  • How the symptoms affect your life
  • Whether you have other conditions, illnesses or diseases such as arthritis
  • Whether you take medicine for other conditions
  • Whether there have been recent changes in your life that are causing you stress

Your doctor also will do a physical examination, and will:

  • Feel your jaw joints and facial muscles
  • Listen for popping or clicking noises as you open and close your mouth
  • Examine how far you can open your mouth
  • Look at your teeth for signs of teeth grinding or clenching, also called bruxism

Usually this is enough information to identify the problem, make a diagnosis and determine the best form of treatment. Your dentist also may take a panoramic X-ray so he or she can see the bony anatomy of the temporomandibular joint. This also allows the dentist to be sure that other problems aren't causing your symptoms.

In some cases, more testing is needed. Your dentist may request magnetic resonance imaging (MRI). This special test provides an image of the TMJ disc and its relation to the ball and socket when the jaw moves. In rare instances, other imaging tests may be needed.

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