T M JD I S O R D E R S

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICESNational Institutes of Health

WHAT IS THETEMPOROMANDIBULAR JOINT?

WHAT ARETMJ DISORDERS?

WHAT CAUSESTMJ DISORDERS?

WHAT ARE THESIGNS AND SYMPTOMS?

HOW ARE TMJDISORDERS DIAGNOSED?

HOW ARE TMJDISORDERS TREATED?

IF YOU THINKYOUHAVE A TMJ DISORDER...

RESEARCH

HOPE FOR THE FUTURE

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CONTENTS

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TMJ DISORDERS

Temporomandibular joint and muscledisorders, commonly called “TMJ,” are agroup of conditions that cause pain anddysfunction in the jaw joint and the musclesthat control jaw movement. We don’t knowfor certain how many people have TMJdisorders, but some estimates suggest thatover 10 million Americans are affected.The condition appears to be more commonin women than men.

For most people, pain in the area of thejaw joint or muscles does not signal aserious problem. Generally, discomfortfrom these conditions is occasional andtemporary, often occurring in cycles. Thepain eventually goes away with little or notreatment. Some people, however, developsignificant, long-term symptoms.

If you have questions about TMJ disorders,you are not alone. Researchers, too, arelooking for answers to what causes theseconditions and what are the best treatments.Until we have scientific evidence for safeand effective treatments, it’s important toavoid, when possible, procedures that cancause permanent changes in your bite orjaw. This booklet provides information youshould know if you have been told by adentist or physician that you have a TMJdisorder.

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WHAT IS THETEMPOROMANDIBULAR JOINT?

The temporomandibular joint connects thelower jaw, called the mandible, to the bone atthe side of the head—the temporal bone. Ifyou place your fingers just in front of yourears and open your mouth, you can feel thejoints. Because these joints are flexible, thejaw can move smoothly up and down andside to side, enabling us to talk, chew andyawn. Muscles attached to and surroundingthe jaw joint control its position and movement.

When we open our mouths, the roundedends of the lower jaw, called condyles, glidealong the joint socket of the temporal bone.The condyles slide back to their originalposition when we close our mouths. To keepthis motion smooth, a soft disc lies betweenthe condyle and the temporal bone. Thisdisc absorbs shocks to the jaw joint fromchewing and other movements.

The temporomandibular joint is differentfrom the body’s other joints. The combinationof hinge and sliding motions makes this jointamong the most complicated in the body.Also, the tissues that make up the temporo-mandibular joint differ from other load-bearingjoints, like the knee or hip. Because of itscomplex movement and unique makeup, thejaw joint and its controlling muscles can posea tremendous challenge to both patients andhealth care providers when problems arise.

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Temporal muscle covering

temporal bone

Disc

Condyle

Masseter muscleMandible

OPEN

CLOSED

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WHAT ARETMJ DISORDERS?

Disorders of the jaw joint and chewingmuscles—and how people respond tothem—vary widely. Researchers generallyagree that the conditions fall into three maincategories:

1 Myofascial pain, the most commontemporomandibular disorder, involves dis-comfort or pain in the muscles that controljaw function.

2 Internal derangement of the joint involvesa displaced disc, dislocated jaw, or injury tothe condyle.

3 Arthritis refers to a group ofdegenerative/inflammatory joint disordersthat can affect the temporomandibular joint.

A person may have one or more of theseconditions at the same time. Some peoplehave other health problems that co-exist withTMJ disorders, such as chronic fatiguesyndrome, sleep disturbances or fibromyal-gia, a painful condition that affects musclesand other soft tissues throughout the body. Itis not known whether these disorders share acommon cause.

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People who have a rheumatic disease,such as rheumatoid arthritis, may developTMJ disease as a secondary condition.Rheumatic diseases refer to a large group ofdisorders that cause pain, inflammation, andstiffness in the joints, muscles, and bone.Both rheumatoid arthritis and some TMJdisorders involve inflammation of the tissuesthat line the joints. The exact relationshipbetween these conditions is not known.

How jaw joint and muscle disordersprogress is not clear. Symptoms worsenand ease over time, but what causes thesechanges is not known. Most people haverelatively mild forms of the disorder. Theirsymptoms improve significantly, or disappearspontaneously, within weeks or months. Forothers, the condition causes long-term,persistent and debilitating pain.

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WHAT CAUSESTMJ DISORDERS?

Trauma to the jaw or temporomandibularjoint plays a role in some TMJ disorders.But for most jaw joint and muscle problems,scientists don’t know the causes. For manypeople, symptoms seem to start withoutobvious reason. Research disputes thepopular belief that a bad bite or orthodonticbraces can trigger TMJ disorders. Becausethe condition is more common in women thanin men, scientists are exploring a possiblelink between female hormones and TMJdisorders.

There is no scientific proof that clickingsounds in the jaw joint lead to serious prob-lems. In fact, jaw clicking is common in thegeneral population. Jaw noises alone, withoutpain or limited jaw movement, do not indicatea TMJ disorder and do not warrant treatment.

The roles of stress and tooth grinding asmajor causes of TMJ disorders are alsounclear. Many people with these disordersdo not grind their teeth, and many long-timetooth grinders do not have painful jointsymptoms. Scientists note that people withsore, tender chewing muscles are less likelythan others to grind their teeth because itcauses pain. Researchers also found thatstress seen in many persons with jaw jointand muscle disorders is more likely the resultof dealing with chronic jaw pain or dysfunctionthan the cause of the condition.

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WHAT ARE THESIGNS AND SYMPTOMS?

A variety of symptoms may be linked toTMJ disorders. Pain, particularly in thechewing muscles and/or jaw joint, is themost common symptom. Other likelysymptoms 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 thejaw joint when opening or closing themouth,

� a change in the way the upper and lowerteeth fit together.

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HOW ARE TMJDISORDERS DIAGNOSED?

There is no widely accepted, standardtest now available to correctly diagnose TMJdisorders. Because the exact causes andsymptoms are not clear, identifying thesedisorders can be difficult and confusing.Currently, health care providers note thepatient’s description of symptoms, take adetailed medical and dental history, andexamine problem areas, including the head,neck, face, and jaw. Imaging studies mayalso be recommended.

You may want to consult your doctor torule out known causes of pain. Facial paincan be a symptom of many other conditions,such as sinus or ear infections, various typesof headaches, and facial neuralgias(nerve-related facial pain). Ruling out theseproblems first helps in identifying TMJdisorders.

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HOW ARE TMJDISORDERS TREATED?

Because more studies are needed on thesafety and effectiveness of most treatmentsfor jaw joint and muscle disorders, expertsstrongly recommend using the most conser-vative, reversible treatments possible.Conservative treatments do not invade the tis-sues of the face, jaw, or joint, or involve sur-gery. Reversible treatments do not causepermanent changes in the structure or posi-tion of the jaw or teeth. Even when TMJ dis-orders have become persistent, most patientsstill do not need aggressive types of treatment.

Conservative TreatmentsBecause the most common jaw joint andmuscle problems are temporary and do notget worse, simple treatment is all that isusually needed to relieve discomfort.

Self-Care PracticesThere are steps you can take that may behelpful in easing symptoms, such as:

� eating soft foods,

� applying ice packs,

� avoiding extreme jaw movements(such as wide yawning, loud singing,and gum chewing),

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� learning techniques forrelaxing and reducing stress,

� practicing gentle jaw stretching and relax-ing exercises that may help increase jawmovement. Your health care provider or aphysical therapist can recommend exer-cises if appropriate for your particular con-dition.

Pain MedicationsFor many people with TMJ disorders, short-term use of over-the-counter pain medicinesor nonsteroidal anti-inflammatory drugs(NSAIDS), such as ibuprofen, may providetemporary relief from jaw discomfort. Whennecessary, your dentist or doctor canprescribe stronger pain or anti-inflammatorymedications, muscle relaxants, or anti-depressants to help ease symptoms.

Stabilization SplintsYour doctor or dentist may recommendan oral appliance, also called a stabilizationsplint or bite guard, which is a plastic guardthat fits over the upper or lower teeth.Stabilization splints are the most widely usedtreatments for TMJ disorders. Studies oftheir effectiveness in providing pain relief,however, have been inconclusive. If a stabi-lization splint is recommended, it should beused only for a short time and should notcause permanent changes in the bite. If asplint causes or increases pain, stop using itand see your health care provider.

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The conservative, reversible treatmentsdescribed are useful for temporary relief ofpain – they are not cures for TMJ disorders.If symptoms continue over time, come backoften, or worsen, tell your doctor.

Irreversible TreatmentsIrreversible treatments that have not beenproven to be effective – and may make theproblem worse – include orthodontics tochange the bite; crown and bridge work tobalance the bite; grinding down teeth tobring the bite into balance, called “occlusaladjustment"; and repositioning splints, alsocalled orthotics, which permanently alter thebite.

SurgeryOther types of treatments, such assurgical procedures, invade the tissues.Surgical treatments are controversial, oftenirreversible, and should be avoided wherepossible. There have been no long-termclinical trials to study the safety and effec-tiveness of surgical treatments for TMJdisorders. Nor are there standards to identifypeople who would most likely benefit fromsurgery. Failure to respond to conservativetreatments, for example, does not automaticallymean that surgery is necessary. If surgery isrecommended, be sure to have the doctorexplain to you, in words you can understand,the reason for the treatment, the risksinvolved, and other types of treatment thatmay be available.

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ImplantsSurgical replacement of jaw joints withartificial implants may cause severe pain andpermanent jaw damage. Some of thesedevices may fail to function properly or maybreak apart in the jaw over time. If you havealready had temporomandibular joint surgery,be very cautious about considering additionaloperations. Persons undergoing multiplesurgeries on the jaw joint generally have apoor outlook for normal, pain-free joint func-tion. Before undergoing any surgery on thejaw joint, it is extremely important to get otherindependent opinions and to fully understandthe risks.

The U.S. Food and Drug Administration (FDA)monitors the safety and effectiveness of medicaldevices implanted in the body, including artificialjaw joint implants. Patients and their healthcare providers can report serious problemswith TMJ implants to the FDA throughMedWatch at www.fda.gov/medwatch ortelephone toll-free at 1-800-332-1088.

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IF YOU THINK YOUHAVE A TMJ DISORDER...

Remember that for most people, discomfortfrom TMJ disorders will eventually go awayon its own. Simple self-care practices areoften effective in easing symptoms. If treat-ment is needed, it should be based on areasonable diagnosis, be conservative andreversible, and be customized to your specialneeds. Avoid treatments that can causepermanent changes in the bite or jaw. Ifirreversible treatments are recommended, besure to get a reliable, independent secondopinion.

Because there is no certified specialty forTMJ disorders in either dentistry or medicine,finding the right care can be difficult. Lookfor a health care provider who understandsmusculoskeletal disorders (affecting muscle,bone and joints) and who is trained in treatingpain conditions. Pain clinics in hospitals anduniversities are often a good source of advice,particularly when pain continues over timeand interferes with daily life. Complex cases,often marked by prolonged, persistent andsevere pain; jaw dysfunction; co-existingconditions; and diminished quality of life,likely require a team of experts from variousfields, such as neurology, rheumatology, painmanagement and others, to diagnose andtreat this condition.

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RESEARCH

The National Institute of Dental andCraniofacial Research (NIDCR), one of theNational Institutes of Health (NIH), leads theFederal research effort on temporomandibularjoint and muscle disorders. In a landmarkstudy, NIDCR is tracking healthy people overtime to identify risk factors that contribute tothe development of these conditions. Thefindings may lead to a better understandingof the onset and natural course of TMJdisorders and potentially to new diagnosticand treatment approaches.

Pain StudiesBecause pain is the major symptom of theseconditions, NIH scientists are conducting awide range of studies to better understandthe pain process, including:

� understanding the nature of facial pain inTMJ disorders and what it may hold incommon with other pain conditions, suchas headache and widespread musclepain,

� exploring differences between men andwomen in how they respond to pain andto pain medications,

� pinpointing factors that lead to chronic orpersistent jaw joint and muscle pain,

� examining the effects of stressors, suchas noise, cold and physical stress, onpain symptoms in patients with TMJdisorders to learn how lifestyle adjus-ments can decrease pain,

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� identifying medications, or combinationsof medications and conservative treat-ments, that will provide effective chronicpain relief,

� investigating possible links betweenosteoarthritis and a history of orofacialpain.

Replacement PartsResearch is also under way to grow humantissue in the laboratory to replace damagedcartilage in the jaw joint. Other studies areaimed at developing safer, more life-likematerials to be used for repairing or replacingdiseased temporomandibular joints, discs,and chewing muscles.

Implant RegistryTo learn more about TMJ implants and theirmedical effects on patients, NIDCR haslaunched a TMJ implant registry. The registrytracks the health of patients who receiveimplants, as well as those who already havethe devices, or who have had them removed.Scientists also examine implants that havebeen removed to learn why problems devel-oped in these patients. By increasingunderstanding of how temporomandibularjoint implants perform and why they often fail,the study will help scientists design safer andmore effective implants. To learn more aboutthe TMJ implant registry, visit the registrywebsite at http://tmjregistry.org.

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HOPE FOR THE FUTURE

The challenges posed by TMJ disordersspan the research spectrum, from causes todiagnosis through treatment and prevention.Researchers throughout the health sciencesare working together not only to gain a betterunderstanding of the temporomandibularjoint and muscle disease process, but also toimprove quality of life for people affected bythese disorders.

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TMJ

TMJ DISORDERS is produced anddistributed by the National Institute ofDental and Craniofacial Research inpartnership with the Office of Researchon Women’s Health, components ofthe National Institutes of Health(NIH) in Bethesda, Maryland. Part ofthe U.S. Department of Health andHuman Services, NIH is one of theworld's foremost medical researchcenters and the Federal focal point formedical research in the United States.

For additional copies of this pamphlet contact:

National Institute of Dental and Craniofacial ResearchNational Oral Health Information Clearinghouse1 NOHIC WayBethesda, MD 20892-3500

301-402-7364www.nidcr.nih.gov

This publication is not copyrighted.Make as many photocopies as you need.

NIH Publication No. 06-3487 Revised June 2006