T M J

D I S O R D E R S

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

National Institutes of Health
WHAT IS THE

TEMPOROMANDIBULAR JOINT?

WHAT ARE

TMJ DISORDERS?

WHAT CAUSES

TMJ DISORDERS?

WHAT ARE THE

SIGNS AND SYMPTOMS?

HOW ARE TMJ

DISORDERS DIAGNOSED?

HOW ARE TMJ

DISORDERS TREATED?

IF YOU THINK YOU

HAVE A TMJ DISORDER...

RESEARCH

HOPE FOR THE FUTURE

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CONTENTS
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TMJ DISORDERS

Temporomandibular joint and muscle

disorders, commonly called “TMJ,” are a

group of conditions that cause pain and

dysfunction in the jaw joint and the muscles

that control jaw movement. We don’t know

for certain how many people have TMJ

disorders, but some estimates suggest that

over 10 million Americans are affected.

The condition appears to be more common

in women than men.

For most people, pain in the area of the

jaw joint or muscles does not signal a

serious problem. Generally, discomfort

from these conditions is occasional and

temporary, often occurring in cycles. The

pain eventually goes away with little or no

treatment. Some people, however, develop

significant, long-term symptoms.

If you have questions about TMJ disorders,

you are not alone. Researchers, too, are

looking for answers to what causes these

conditions and what are the best treatments.

Until we have scientific evidence for safe

and effective treatments, it’s important to

avoid, when possible, procedures that can

cause permanent changes in your bite or

jaw. This booklet provides information you

should know if you have been told by a

dentist or physician that you have a TMJ

disorder.
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WHAT IS THE

TEMPOROMANDIBULAR JOINT?

The temporomandibular joint connects the

lower jaw, called the mandible, to the bone at

the side of the head—the temporal bone. If

you place your fingers just in front of your

ears and open your mouth, you can feel the

joints. Because these joints are flexible, 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 jaw joint from

chewing and other movements.

The temporomandibular joint is different

from the body’s other joints. The combination

of hinge and sliding motions makes this joint

among the most complicated in the body.

Also, the tissues that make up the temporomandibular joint differ from other load-bearing

joints, like the knee or hip. Because of its

complex movement and unique makeup, the

jaw joint and its controlling muscles can pose

a tremendous challenge to both patients and

health care providers when problems arise.
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Temporal muscle covering

temporal bone

Disc

Condyle

Masseter muscle

Mandible

OPEN

CLOSED
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WHAT ARE

TMJ DISORDERS?

Disorders of the jaw joint and chewing

muscles—and how people respond to

them—vary widely. Researchers generally

agree that the conditions fall into three main

categories:

1 Myofascial pain, the most common

temporomandibular disorder, involves discomfort or pain in the muscles that control

jaw function.

2 Internal derangement of the joint involves

a displaced disc, dislocated jaw, or injury to

the condyle.

3 Arthritis refers to a group of

degenerative/inflammatory joint disorders

that can affect the temporomandibular joint.

A person may have one or more of these

conditions at the same time. Some people

have other health problems that co-exist with

TMJ disorders, such as chronic fatigue

syndrome, sleep disturbances or fibromyalgia, a painful condition that affects muscles

and other soft tissues throughout the body. It

is not known whether these disorders share a

common cause.
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People who have a rheumatic disease,

such as rheumatoid arthritis, may develop

TMJ disease as a secondary condition.

Rheumatic diseases refer to a large group of

disorders that cause pain, inflammation, and

stiffness in the joints, muscles, and bone.

Both rheumatoid arthritis and some TMJ

disorders involve inflammation of the tissues

that line the joints. The exact relationship

between these conditions is not known.

How jaw joint and muscle disorders

progress is not clear. Symptoms worsen

and ease over time, but what causes these

changes is not known. Most people have

relatively mild forms of the disorder. Their

symptoms improve significantly, or disappear

spontaneously, within weeks or months. For

others, the condition causes long-term,

persistent and debilitating pain.

TMJ
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WHAT CAUSES

TMJ DISORDERS?

Trauma to the jaw or temporomandibular

joint plays a role in some TMJ disorders.

But for most jaw joint and muscle problems,

scientists don’t know the causes. For many

people, symptoms seem to start without

obvious reason. Research disputes the

popular belief that a bad bite or orthodontic

braces can trigger TMJ disorders. Because

the condition is more common in women than

in men, scientists are exploring a possible

link between female hormones and TMJ

disorders.

There is no scientific proof that clicking

sounds in the jaw joint lead to serious problems. In fact, jaw clicking is common in the

general population. Jaw noises alone, without

pain or limited jaw movement, do not indicate

a TMJ disorder and do not warrant treatment.

The roles of stress and tooth grinding as

major causes of TMJ disorders are also

unclear. Many people with these disorders

do not grind their teeth, and many long-time

tooth grinders do not have painful joint

symptoms. Scientists note that people with

sore, tender chewing muscles are less likely

than others to grind their teeth because it

causes pain. Researchers also found that

stress seen in many persons with jaw joint

and muscle disorders is more likely the result

of dealing with chronic jaw pain or dysfunction

than the cause of the condition.
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WHAT ARE THE

SIGNS AND SYMPTOMS?

A variety of symptoms may be linked to

TMJ disorders. Pain, particularly in the

chewing muscles and/or jaw joint, is the

most common symptom. Other likely

symptoms include:

■ radiating pain in the face, jaw, or neck,

■ jaw muscle stiffness,

■ limited movement or locking of the jaw,

■ painful clicking, popping or grating in the

jaw joint when opening or closing the

mouth,

■ a change in the way the upper and lower

teeth fit together.

TMJ
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HOW ARE TMJ

DISORDERS DIAGNOSED?

There is no widely accepted, standard

test now available to correctly diagnose TMJ

disorders. Because the exact causes and

symptoms are not clear, identifying these

disorders can be difficult and confusing.

Currently, health care providers note the

patient’s description of symptoms, take a

detailed medical and dental history, and

examine problem areas, including the head,

neck, face, and jaw. Imaging studies may

also be recommended.

You may want to consult your doctor to

rule out known causes of pain. Facial pain

can be a symptom of many other conditions,

such as sinus or ear infections, various types

of headaches, and facial neuralgias

(nerve-related facial pain). Ruling out these

problems first helps in identifying TMJ

disorders.
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HOW ARE TMJ

DISORDERS TREATED?

Because more studies are needed on the

safety and effectiveness of most treatments

for jaw joint and muscle disorders, experts

strongly recommend using the most conservative, reversible treatments possible.

Conservative treatments do not invade the tissues of the face, jaw, or joint, or involve surgery. Reversible treatments do not cause

permanent changes in the structure or position of the jaw or teeth. Even when TMJ disorders have become persistent, most patients

still do not need aggressive types of treatment.

Conservative Treatments

Because the most common jaw joint and

muscle problems are temporary and do not

get worse, simple treatment is all that is

usually needed to relieve discomfort.

Self-Care Practices

There are steps you can take that may be

helpful in easing symptoms, such as:

■ eating soft foods,

■ applying ice packs,

■ avoiding extreme jaw movements

(such as wide yawning, loud singing,

and gum chewing),

TMJ
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■ learning techniques for

relaxing and reducing stress,

■ practicing gentle jaw stretching and relaxing exercises that may help increase jaw

movement. Your health care provider or a

physical therapist can recommend exercises if appropriate for your particular condition.

Pain Medications

For many people with TMJ disorders, shortterm use of over-the-counter pain medicines

or nonsteroidal anti-inflammatory drugs

(NSAIDS), such as ibuprofen, may provide

temporary relief from jaw discomfort. When

necessary, your dentist or doctor can

prescribe stronger pain or anti-inflammatory

medications, muscle relaxants, or antidepressants to help ease symptoms.

Stabilization Splints

Your doctor or dentist may recommend

an oral appliance, also called a stabilization

splint or bite guard, which is a plastic guard

that fits over the upper or lower teeth.

Stabilization splints are the most widely used

treatments for TMJ disorders. Studies of

their effectiveness in providing pain relief,

however, have been inconclusive. If a stabilization splint is recommended, it should be

used only for a short time and should not

cause permanent changes in the bite. If a

splint causes or increases pain, stop using it

and see your health care provider.
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The conservative, reversible treatments

described are useful for temporary relief of

pain – they are not cures for TMJ disorders.

If symptoms continue over time, come back

often, or worsen, tell your doctor.

Irreversible Treatments

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.

Surgery

Other types of treatments, such as

surgical procedures, invade the tissues.

Surgical treatments are controversial, often

irreversible, and should be avoided where

possible. There have been no long-term

clinical trials to study the safety and effectiveness of surgical treatments for TMJ

disorders. Nor are there standards to identify

people who would most likely benefit from

surgery. Failure to respond to conservative

treatments, for example, does not automatically

mean that surgery is necessary. If surgery is

recommended, be sure to have the doctor

explain to you, in words you can understand,

the reason for the treatment, the risks

involved, and other types of treatment that

may be available.

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Implants

Surgical replacement of jaw joints with

artificial implants may cause severe pain and

permanent jaw damage. Some of these

devices may fail to function properly or may

break apart in the jaw over time. If you have

already had temporomandibular joint surgery,

be very cautious about considering additional

operations. Persons undergoing multiple

surgeries on the jaw joint generally have a

poor outlook for normal, pain-free joint function. Before undergoing any surgery on the

jaw joint, it is extremely important to get other

independent opinions and to fully understand

the risks.

The U.S. Food and Drug Administration (FDA)

monitors the safety and effectiveness of medical

devices implanted in the body, including artificial

jaw joint implants. Patients and their health

care providers can report serious problems

with TMJ implants to the FDA through

MedWatch at www.fda.gov/medwatch or

telephone toll-free at 1-800-332-1088.
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IF YOU THINK YOU

HAVE A TMJ DISORDER...

Remember that for most people, discomfort

from TMJ disorders will eventually go away

on its own. Simple self-care practices are

often effective in easing symptoms. If treatment is needed, it should be based on a

reasonable diagnosis, be conservative and

reversible, and be customized to your special

needs. Avoid treatments that can cause

permanent changes in the bite or jaw. If

irreversible treatments are recommended, be

sure to get a reliable, independent second

opinion.

Because there is no certified specialty for

TMJ disorders in either dentistry or medicine,

finding the right care can be difficult. Look

for a health care provider who understands

musculoskeletal disorders (affecting muscle,

bone and joints) and who is trained in treating

pain conditions. Pain clinics in hospitals and

universities are often a good source of advice,

particularly when pain continues over time

and interferes with daily life. Complex cases,

often marked by prolonged, persistent and

severe pain; jaw dysfunction; co-existing

conditions; and diminished quality of life,

likely require a team of experts from various

fields, such as neurology, rheumatology, pain

management and others, to diagnose and

treat this condition.

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RESEARCH

The National Institute of Dental and

Craniofacial Research (NIDCR), one of the

National Institutes of Health (NIH), leads the

Federal research effort on temporomandibular

joint and muscle disorders. In a landmark

study, NIDCR is tracking healthy people over

time to identify risk factors that contribute to

the development of these conditions. The

findings may lead to a better understanding

of the onset and natural course of TMJ

disorders and potentially to new diagnostic

and treatment approaches.

Pain Studies

Because pain is the major symptom of these

conditions, NIH scientists are conducting a

wide range of studies to better understand

the pain process, including:

■ understanding the nature of facial pain in

TMJ disorders and what it may hold in

common with other pain conditions, such

as headache and widespread muscle

pain,

■ exploring differences between men and

women in how they respond to pain and

to pain medications,

■ pinpointing factors that lead to chronic or

persistent jaw joint and muscle pain,

■ examining the effects of stressors, such

as noise, cold and physical stress, on

pain symptoms in patients with TMJ

disorders to learn how lifestyle adjusments can decrease pain,
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■ identifying medications, or combinations

of medications and conservative treatments, that will provide effective chronic

pain relief,

■ investigating possible links between

osteoarthritis and a history of orofacial

pain.

Replacement Parts

Research is also under way to grow human

tissue in the laboratory to replace damaged

cartilage in the jaw joint. Other studies are

aimed at developing safer, more life-like

materials to be used for repairing or replacing

diseased temporomandibular joints, discs,

and chewing muscles.

Implant Registry

To learn more about TMJ implants and their

medical effects on patients, NIDCR has

launched a TMJ implant registry. The registry

tracks the health of patients who receive

implants, as well as those who already have

the devices, or who have had them removed.

Scientists also examine implants that have

been removed to learn why problems developed in these patients. By increasing

understanding of how temporomandibular

joint implants perform and why they often fail,

the study will help scientists design safer and

more effective implants. To learn more about

the TMJ implant registry, visit the registry

website at http://tmjregistry.org.

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HOPE FOR THE FUTURE

The challenges posed by TMJ disorders

span the research spectrum, from causes to

diagnosis through treatment and prevention.

Researchers throughout the health sciences

are working together not only to gain a better

understanding of the temporomandibular

joint and muscle disease process, but also to

improve quality of life for people affected by

these disorders.
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TMJ

TMJ DISORDERS is produced and

distributed by the National Institute of

Dental and Craniofacial Research in

partnership with the Office of Research

on Women’s Health, components of

the National Institutes of Health

(NIH) in Bethesda, Maryland. Part of

the U.S. Department of Health and

Human Services, NIH is one of the

world's foremost medical research

centers and the Federal focal point for

medical research in the United States.
For additional copies of this pamphlet contact:

National Institute of Dental and Craniofacial Research

National Oral Health Information Clearinghouse

1 NOHIC Way

Bethesda, MD 20892-3500

301-402-7364

www.nidcr.nih.gov

This publication is not copyrighted.

Make as many photocopies as you need.

NIH Publication No. 06-3487 Revised June 2006