TMJ & TMD: temporomandibular joint and muscle disorders

TMD stands for temporomandibular disorders, and it refers to a problem with the temporomandibular joint, or TMJ. Many use the terms TMJ and TMD interchangeably, but it is more accurate to use TMD when referring to the group of conditions that cause pain and dysfunction in the jaw joint and muscles that control chewing, and to use TMJ when referring to the joint itself. Although we don't know how many people have TMD, some estimates suggest that over 10 million people in the United States are affected, with twice as many women impacted as men.

Injury plays a role in some TMJ problems, but for many people symptoms seem to start for no obvious reason. The good news is that for most people, clicking, popping or pain in the area of the jaw joint or muscles does not signal a serious problem. Generally, discomfort from TMD is occasional and temporary, often occurring in cycles. The pain eventually goes away with little or no treatment, and only a small percentage of people with TMD develop significant, long-term symptoms. For these individuals, however, TMD can be a major health problem that can severely affect quality of life.

If you have questions about TMD, you are not alone. Researchers continue to investigate the causes of TMD and the best ways to diagnose, treat and prevent the disorders resulting from it.

What is the TMJ?

The TMJ, or the temporomandibular joint, connects the lower jaw to the temporal bones at the side of the skull. If you place your fingers in front of your ears and open your mouth, you can feel the joint on each side of your head. Because these joints function as both sliding and hinge joints, the jaw can move smoothly up and down and side to side, enabling us to talk, chew and yawn. Muscles attached to and surrounding the jaw joint control its position and movement.

When we open our mouths, the rounded ends of the lower jaw, called condyles, glide along the joint socket of the temporal bone. The condyles slide back to their original position when we close our mouths. To keep this motion smooth, a soft disc lies between the condyle and the temporal bone. This disc absorbs shocks to the TMJ from chewing and other movements.

What are TMDs (temporomandibular disorders)?

Today, researchers generally agree that temporomandibular disorders fall into three main categories:

  • Myofascial pain: The most common form of TMD, causing discomfort or pain in the muscles that control jaw function, along with the neck and shoulder muscles, is myofascial pain.
  • Internal derangement of the joint: A dislocated jaw, displaced disc, or injury to the condyle may result in internal derangement of the joint.
  • Degenerative joint disease: Osteoarthritis, rheumatoid arthritis, or other diseases in the jaw joint are examples of degenerative joint disease.

A person may have one or more of these conditions at the same time.

What causes TMJ pain & TMD?

 An injury to the jaw or temporomandibular joint can cause TMD. A heavy blow, for example, can fracture the bones of the joint or damage the disc, disrupting the smooth motion of the jaw and causing pain or locking. Arthritis in the jaw joint may also result from injury and cause pain. Other causes of TMD are less clear.  Some have suggested, for example, that a misaligned bite (malocclusion) and orthodontic treatments such as braces and the use of headgear are to blame for some forms of TMD, but recent studies show that these claims probably are unfounded.

There also is no scientific proof that gum chewing causes clicking sounds in the jaw joint, or that jaw clicking leads to serious TMJ problems. In fact, jaw noises are common in the general population, and researchers believe that most people with clicking or popping in the jaw joint likely have a displaced disc. This means the soft, shock-absorbing disc is not in its normal position. And, if there are no other symptoms, such as pain or locking, jaw clicking or popping usually does not need treatment.

Some experts suggest that mental or physical stress may cause or aggravate TMD. People with TMD often clench or grind their teeth at night, which can tire the jaw muscles and lead to pain. It is not clear whether stress causes clenching, grinding and the related jaw pain, or is itself a result of chronic jaw pain. Scientists are exploring how behavioral, psychological and physical factors may combine to cause TMD.

TMD symptoms

A variety of symptoms may be linked to TMD. Pain, particularly in the chewing muscles and jaw joint, is the most common symptom. Other signs and symptoms include:

  • Sticking and limited movement in the jaw joint, or a total inability to move the jaw, known as “lockjaw”
  • Severe pain or discomfort in the face, neck or shoulders, especially while chewing, speaking or opening your mouth wide
  • Painful clicking, popping or grating sounds in the jaw joint, when opening or closing the mouth
  • A sudden, major change in the way the upper and lower teeth fit together
  • Trouble chewing
  • Swelling on the side of the face
  • Tired feeling in the facial muscles
  • Headaches, including migraines, earaches, itching feeling in the ear, toothaches, dizziness, hearing problems, and ringing in the ears (tinnitus)

Occasional discomfort in the jaw joint or chewing muscles is quite common and generally not a cause for concern. Other diseases, including tooth decay, sinus issues, arthritis and gum disease, can show similar symptoms. Researchers studying TMD symptoms hope to develop more effective diagnosis and treatment methods.

TMD diagnosis for TMJ pain

Because the exact causes and symptoms of TMD are not clear, diagnosing these disorders can be confusing. At present, there is no universal, standard test to diagnose TMD. An examination includes feeling the jaw joints and chewing muscles for pain or tenderness, and your dentist will listen for clicking, popping or grating sounds during jaw movement. They will also look for limited motion or locking of the jaw while opening or closing the mouth. Checking the patient's dental and medical history is also very important. Indeed, in about 90 percent of cases, the patient's description of symptoms, combined with the physical exam of the face and jaw, provides enough information to diagnose these disorders and make treatment recommendations.

Regular dental X-rays and TMJ X-rays (transcranial radiographs) offer limited help in diagnosing TMD. Depending on the severity and duration of your symptoms, your dentist may use other X-ray techniques instead, such as arthrography (joint X-rays using dye), magnetic resonance imaging (MRI) and tomography (a special type of X-ray). These are used when the practitioner suspects a condition, such as arthritis, or when significant pain persists over time and symptoms do not improve with treatment. Before undergoing any expensive diagnostic tests or treatments, it may beneficial to get a second opinion.

At-home TMD treatments

TMD treatments should always be conservative and reversible. Conservative treatments are minimally invasive, making no changes to the teeth, jaws or joints. Reversible treatments do not cause permanent or irreversible changes in the structure or position of the jaw or teeth.

Because most TMD problems are temporary and do not progress, simple treatments usually work to relieve discomfort. Self-care practices like eating soft foods, applying heat or ice packs, and avoiding extreme jaw movements can ease TMD symptoms. Learning relaxation techniques for reducing stress may also be helpful.

Other conservative treatments include at-home physical therapy, which focuses on gentle muscle stretching and relaxing exercises. Short-term use of muscle-relaxing and anti-inflammatory drugs can aid these exercises.

Your health care provider may recommend an oral appliance, such as a nightguard, which is a plastic guard that fits over the upper or lower teeth, or a splint, which helps reduce clenching and grinding and eases muscle tension. A splint should be used for only a short time, to avoid causing permanent changes in the bite, and if it increases the pain, stop using it and see your practitioner.

The conservative, reversible treatments described above are useful for temporary relief of pain and muscle spasm. They are not cures for TMD. If symptoms continue over time, or recur often, check with your doctor.

Treatments for chronic TMD

Treatments for chronic TMD include non-invasive and invasive options. Non-invasive transcutaneous electrical nerve stimulation (TENS) uses low-level electrical currents to relax jaw muscles. Ultrasound technology delivers pain-soothing penetrative heat to the jaw muscles. Radio wave therapy that stimulates the TMJ and increases blood flow can ease pain. Low-level laser therapy lessens inflammation for greater range of motion in the neck and jaw. Studies of the overall effectiveness of these modalities have been inconclusive. More invasive treatments have been performed with limited success, such as injecting anesthetics into painful muscle sites, often called "trigger points." Another is arthroscopy, where the doctor inserts the arthroscope in an incision near the ear to visualize the joint interior and then removes inflamed tissue and corrects joint alignment.

Irreversible treatments that have not been proven to be effective — and may make the problem worse — include orthodontics to change the bite; crown and bridge work to balance the bite; grinding down teeth to bring the bite into balance, called “occlusal adjustment”; and repositioning splints, also called orthotics, which permanently alter the bite. When no other option suffices, doctors may turn to open-joint surgery. This most invasive of all TMD treatments requires opening the entire temporomandibular area to remove scarred or damaged tissue and bone fragments.

Surgical treatments are often irreversible and should be avoided, when possible. When surgery is necessary, be sure to have the doctor explain in plain words the reason for the treatment, the risks involved, and other types of treatment that may be available.

Dangers of irreversible treatments

Scientists have learned that certain irreversible treatments, such as surgical replacement of jaw joints with artificial implants, may cause severe pain and permanent jaw damage. Also, some of these devices fail to function properly or break apart in the jaw over time, and there have been no long-term studies to test the safety and effectiveness of these procedures. Before undergoing any surgery on the jaw joint, it is crucial to get other independent opinions and to fully understand your risks.

Although more studies are needed on the safety and effectiveness of most TMD treatments, scientists strongly recommend using the most conservative, reversible treatments possible before considering invasive options. Even for chronic TMD problems, most patients do not need aggressive treatment.

TMD diagnosis and second opinions

Many dental practitioners are familiar with the conservative treatment of TMD. Look for one who understands musculoskeletal disorders (affecting muscle, bone and joints), and who is trained in treating pain conditions. Because TMD is usually painful, pain clinics in hospitals and universities are also a good source of advice and second opinions. Specially trained facial pain experts can often be helpful in diagnosing and treating TMD.




TMJ Disorders. National Institute of Dental and Craniofacial Research.  NIH Publication No. 17-3487.  2017. Accessed July 2018.

Less Is Often Best In Treating TMJ Disorders. National Institute of Dental and Craniofacial Research. 2013 Accessed July 2018.

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