TMD brochure

TEMPOROMANDIBULAR
DISORDERS

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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
National Institutes of Health

CONTENTS
2 WHAT IS THE
TEMPOROMANDIBULAR JOINT?

4 WHAT ARE TEMPOROMANDIBULAR
DISORDERS?

6 WHAT CAUSES
TEMPOROMANDIBULAR DISORDERS?

7 WHAT ARE THE

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SIGNS AND SYMPTOMS?

8 HOW ARE TEMPOROMANDIBULAR
DISORDERS DIAGNOSED?

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9 HOW ARE TEMPOROMANDIBULAR
DISORDERS TREATED?

13 IF YOU THINK YOU HAVE A

TEMPOROMANDIBULAR DISORDER …

14 RESEARCH
17 HOPE FOR THE FUTURE

TEMPOROMANDIBULAR
DISORDERS
Temporomandibular joint and muscle
disorders, commonly called “TMDs,” 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 TMDs,
but some estimates suggest that over
10 million Americans are affected. The
condition appears to be more common in
women than men.

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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 temporary, often occurring in
cycles. The pain eventually goes away with
little or no treatment. Some people, however,
develop significant, long-term symptoms.

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If you have questions about TMDs, you
are not alone. Researchers, too, are
looking for answers to what causes these
conditions and what the best treatments
are. 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
temporomandibular 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.

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When we open our mouths, the rounded ends
of the lower jaw joint, 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.

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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 loadbearing 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

CLOSED

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OPEN

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WHAT ARE
TEMPOROMANDIBULAR
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 Myalgia or myofascial pain involves
discomfort or pain in the muscles that control
jaw function.

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2 Intra-articular disorders are a group of
biomechanical disorders involving the disccondyle complex, such as a displaced disc,
dislocated jaw, or degenerative joint disease
that causes deterioration of the disc and/or
changes in the condyle.

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3 Arthralgia refers to inflammation and pain in
the temporomandibular joint.

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TMD
A person may have one or more of these
disorders at the same time. Some people
have other health problems that co-exist with
TMDs such as chronic fatigue syndrome,
sleep disturbances, anxiety, depression,
or chronic pain in other parts of the body,
as well as fibromyalgia, a painful condition
that affects muscles and other soft tissues
throughout the body. Some of these
co-existing conditions may share common
symptoms, which suggest they may share
similar underlying mechanisms of disease.
However, it is not known whether they have a
common cause.

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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.

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WHAT CAUSES
TEMPOROMANDIBULAR
DISORDERS?
Trauma to the jaw or temporomandibular
joint plays a role in some TMDs. However,
for many people symptoms seem to start
without obvious reason and are more
common in women than in men. Scientists
are investigating the potential role of female
hormones, and genetic and environmental
factors in the development of TMDs.

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Research does not support the popular belief
that a bad bite or orthodontic braces can
trigger TMDs. There is no scientific proof
that sounds alone—such as clicking—in
the jaw joint leads to serious problems. In
fact, jaw sounds are common in the general
population. Jaw noises alone, without pain
or limited jaw movement, do not indicate
a temporomandibular disorder and do not
warrant treatment.

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TMD
WHAT ARE THE SIGNS
AND SYMPTOMS?
A variety of symptoms may be linked to TMDs.
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

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■ 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

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■ headache or pain in neck and shoulder
muscles

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HOW ARE
TEMPOROMANDIBULAR
DISORDERS DIAGNOSED?
There is no widely accepted, standard
test now available to correctly diagnose
temporomandibular 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, review oral habits and
psychological stressors, and examine
problem areas, including the head, neck,
face, and jaw. Imaging studies may also be
recommended.

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You may want to consult your doctor to
rule out other known causes of pain. Facial
pain can be a symptom of many conditions,
such as sinus or ear infections, various
types of headaches, and facial neuralgias
(nerve-related facial pain). Ruling out these
problems helps in identifying TMDs.

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TMD
HOW ARE TEMPOROMANDIBULAR
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 temporomandibular disorders have
become persistent, most patients still do not need
aggressive types of treatment.

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Conservative Treatments

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Because many jaw joint and muscle problems
are temporary, simple treatment may be all that is
necessary 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 and repetitive jaw movements
(such as wide yawning, loud singing, and gum
chewing),
■ 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.

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Pain Medications
For many people with temporomandibular
disorders, short-term use of over-thecounter pain medicines or nonsteroidal
anti-inflammatory drugs (NSAIDs), such
as ibuprofen, may provide temporary relief
from jaw discomfort. When necessary, your
dentist or physician can prescribe stronger
anti-inflammatory medications, muscle
relaxants, or anti-depressants to help ease
symptoms.

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Bite Splints

Your physician or dentist may recommend
an oral appliance, also called a bite splint
or bite guard, which is a plastic guard that
fits over the upper or lower teeth. Splints are
a widely used treatment for TMDs because
they may relieve jaw muscle tension or
oral habits such as clenching. Studies of
their effectiveness in providing pain relief,
however, have been inconclusive. If a
bite splint is recommended, it should not
cause permanent changes in the bite. If a
splint causes or increases pain, or affects
your bite, stop using it and see your health
care provider. The conservative, reversible
treatments described are useful for relief
of temporary pain—they are not cures for
TMDs. If symptoms continue over time, come
back often, or worsen, tell your doctor.

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TMD
Botox
Botox® (botulinum toxin type A) is a drug
made from the same bacterium that causes
food poisoning. Used in small doses, Botox
injections can actually help alleviate some
health problems and have been approved
by the Food and Drug Administration (FDA)
for certain disorders. However, Botox is
currently not approved by the FDA for use in
TMDs. Results from recent clinical studies are
inconclusive regarding the effectiveness of
Botox for treatment of chronic TMDs.

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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.

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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 TMDs. 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.
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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.

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.

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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 implants to the FDA
through MedWatch at www.fda.gov/medwatch
or telephone toll-free at 1–800 –332 –1088.

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TMD
IF YOU THINK YOU HAVE
A TEMPOROMANDIBULAR
DISORDER …
Remember that for most people, discomfort
from TMDs 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.

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Because there is no certified specialty for TMDs
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 orofacial pain
conditions. Pain clinics in hospitals and
universities may be 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), part of the
National Institutes of Health (NIH), leads the
federal research effort on TMDs. Here are
some highlights of NIDCR research in
this area:

The Orofacial Pain: Prospective
Evaluation and Risk Assessment
(OPPERA) study

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In this landmark study launched in 2005,
NIDCR-funded scientists tracked nearly
3,000 healthy adults over several years to
identify risk factors that contribute to the
development of TMD. In the second phase
of the study, the researchers followed
participants who were diagnosed with TMD
to determine why some went on to develop
a chronic form of the condition. Scientists
identified several pain-related clinical
symptoms and designed a mathematical
model that strongly predicts greater risk
of progressing from acute to chronic
TMD. These predictive clinical signs and
symptoms may help clinicians identify
the most at-risk patients and take steps
to prevent or provide earlier treatment for
chronic painful TMD. Researchers are
continuing to analyze data from this study,
including looking for genes associated with
TMD risk, identifying potential biomarkers of
the condition, and investigating other pain
conditions that overlap with TMD.

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TMD
Pain Studies
NIDCR scientists are conducting a wide range
of pain studies to better understand the pain
process, including:
■ Understanding the causes of facial pain in TMD
disorders and what biological pathways it may
have in common with other pain conditions, such
as headache and widespread muscle pain;
■ Establishing why craniofacial pain is often more
severe and emotionally draining than pain in other
areas of the body;

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■ Pinpointing factors that lead to chronic or
persistent jaw joint and muscle pain;

■ Determining the genetic factors that contribute to
pain and how patients respond to and manage
pain;

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■ Advancing the discovery and validation of
biomarkers for pain research and treatment;

■ Exploring differences between men and women in
how they respond to pain and pain medications;
■ Examining the effects of stressors, such as noise,
cold, and physical stress, on pain symptoms in
patients with TMD disorders to learn how lifestyle
adjustments can decrease pain;
■ Clarifying pain mechanisms and new biological
targets for treatment of pain;
■ Identifying medications, or combinations of
medications and conservative treatments (as
described on page 9), that will provide effective
chronic pain relief; and
■ Identifying factors contributing to TMD treatment
adherence and evaluating the effect of different
treatments on pain intensity and jaw function.

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TMD Tissue Repair
NIDCR-supported researchers are using
regenerative medicine techniques to develop
strategies for regrowing or replacing tissues
damaged by TMD. Scientists are:
■ studying stem cells that may be used to
regenerate and repair cartilage;
■ developing delivery techniques for stem-cell
based therapies;
■ creating and improving animal models for
studying and testing temporomandibular joint
tissue regeneration; and

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■ improving current implant devices and
developing safer, more life-like materials for use
in repairing or replacing damaged joints, discs
and chewing muscles.

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National Academy of Sciences
Consensus Report

NIDCR sponsored the development of a
consensus report on temporomandibular
disorders by the National Academy of
Sciences (NAS). The NAS expert committee
assessed the current state of knowledge
about TMDs, safety and efficacy of treatments,
and burden and costs associated with
TMD. The report provides recommendations
for enhancing research, training, and
education to enable development of
effective, evidence-based therapies. For
more information, visit the NAS web page
Temporomandibular Disorders (TMD): From
Research Discoveries to Clinical Treatment at
https://www.nationalacademies.org/our-work/
temporomandibular-disorders-tmd-fromresearch-discoveries-to-clinical-treatment.
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TMD
HOPE FOR THE FUTURE
The challenges posed by TMD span
the research spectrum, from causes to
diagnosis to treatment and prevention.
Researchers throughout the health
sciences are working to gain a better
understanding of TMD by studying
the mechanisms of the disorder, the
progression from acute to chronic disease,
new methods of diagnosis, and how
best to offer personalized treatment.
The ultimate goal of such research is to
improve the quality of life for those with this
painful disorder.

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For more copies contact:
National Institute of Dental and Craniofacial Research
National Oral Health Information Center
1 NOHIC Way
Bethesda, MD 20892-3500
1–866–232–4528
www.nidcr.nih.gov
This publication is not copyrighted.
Make as many photocopies as you need.

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NIH Publication No. XX-3487

May 2020

NIH…Turning Discovery Into Health ®