Temporomandibular Disorder (TMD) Definition
Temporomandibular disorder (TMD) refers to pain and dysfunction of the chewing muscles and temporomandibular joints (TMJs) from various causes. TMJs are symmetrical joints that connect the temporal bones of the skull to the jawbone (the mandible). TMD most commonly develops in women between 20 and 40 years of age .
The main approach to TMD should be the prevention and removal of the underlying causes rather than physiotherapy and jaw exercises.
What do TMJ, TMD and TMJD stand for?
- TMJ stands for temporomandibular joint, but the acronym is also often used as short for temporomandibular disorder.
- TMD stands for temporomandibular disorder and TMJD for temporomandibular joint dysfunction, which are two names for the same condition.
Symptoms and Signs of TMD
- Intermittent dull or severe pain in the jaw, in front of the bottom part of the ear (tragus) on one or both sides, especially when opening the mouth or chewing or when exposed to cold wind
- Tenderness or swelling in front of the ear
- Stiffness and tightness of the chewing muscles, decreased range of motion of the jaw (lockjaw or trismus) and clicking, popping or grating sounds during the jaw movements
- Trigger points in the chewing muscles from which pain can radiate to the ears, cheeks, temples, behind the eyes, to the neck or shoulders (myofascial pain) .
- Lateral deviation of the jaw
- Fullness or ringing in the ears (tinnitus), vertigo
- Throat pain without infection, difficulty swallowing
- Numbness in the hands
- References: [1,2,30,31,40,45]
Individuals with TMD also often suffer from insomnia, tension headache, migraine, chronic lower back pain, fibromyalgia, chronic fatigue syndrome (CFS), irritable bowel syndrome, interstitial cystitis, dizziness and vulvar pain (vulvodynia) [8,9,32,33,43]. Sometimes, these problems can be a part of a psychosomatic disorder (due to psychological stress) or central sensitization disorder (due to increased perception of pain by the brain).
Symptoms not typical for TMD:
- Nausea (more likely in acid reflux and stomach problems)
- Fever (more likely in strep throat)
- Facial numbness (can occur in TMD, but more likely results from damage to the trigeminal or cervical nerve, multiple sclerosis or stroke)
Causes and Risk Factors for TMD
1. Increased tension in the chewing muscles
Increased tension in the chewing muscles can result from:
- Psychological problems, such as stress , frustration, fear and repressed anger , anxiety , depression , bipolar disorder  and schizophrenia 
- Overuse of the chewing muscles: gum chewing, eating hard-to-chew foods, nail biting, singing, playing a wind instrument [2,1]
- Poor posture (poking chin, holding your head up by cradling the jaw in a hand, holding the phone between the ear and shoulder, playing violin) or wearing a helmet [23,24]
- Sleep deprivation, obstructive sleep apnea 
- Whiplash  or other neck or head trauma
2. Disorders of the Temporomandibular Joint (TMJ)
The following disorders of TMJ can cause TMD:
- TMJ disc displacement [1,47,48]
- TMJ dislocation (luxation or subluxation, which is usually bilateral) due to over function, for example, forceful opening of the mouth while yawning, singing, laughing, yelling, vomiting or during dental work or due to TMJ hypermobility (in Marfan and Down’s syndrome) 
- Infection or arthritis (osteoarthritis, rheumatoid arthritis, systemic lupus erythematosus (SLE)  gout, psoriasis or ankylosing spondylitis), which can result in inflammation of the TMJ synovial membrane (synovitis) or capsule (capsulitis) or abnormal adhesion of the jaw and temporal bones (ankylosis)
- Tumors in the TMJ 
- TMJ hypomobility (in scleroderma) 
Video 1. Temporomandibular disorder due to disc displacement
3. Other Risk Factors for TMD
- Genetic predisposition 
- Increased sensitivity to pain 
- Wisdom tooth extraction 
The following may not be as important factors in the development of TMD as previously believed:
- Uneven bite (dental malocclusion) and other congenital disorders of the teeth and mouth 
- Teeth grinding and clenching (bruxism) [19,20,21,22,34]
Diagnosis of TMD
A doctor can often make a diagnosis of TMD after a simple physical examination. Sometimes a careful dental, orthopedic or neurological examination is required.
Computer tomography (CT) or magnetic resonance imaging (MRI) can reveal TMJ dislocation, disc displacement or arthritis.
An endoscopic investigation (arthroscopy) can reveal problems within the temporomandibular joint in detail.
Treatment of TMD
Heat pads applied for 15 minutes each hour, several hours during a day, may help relieve pain caused by increased muscle tension .
Ice packs wrapped in a cloth and applied for 10-15 minutes several times per day may reduce pain in inflammation of the TMJ with swelling, for example, due to rheumatoid arthritis .
Sleeping on the side with a pillow support between your shoulder and jaw can keep your neck muscles relaxed and thus decrease jaw pain that arises from the neck overuse .
Medications and Physiotherapy
There is INSUFFICIENT EVIDENCE about the effectiveness of analgesics , such as over-the-counter nonsteroidal anti-inflammatory drugs (acetaminophen, aspirin, ibuprofen), steroid (prednisone) injections, trigger point injections of a local anesthetic , muscle relaxants or tricyclic antidepressants, physiotherapy including jaw exercises [28,29] and manual therapy (massage, myofascial release) [25,26,29], behavioral therapy , bite guards (occlusal splints, braces) [17,35], transcutaneous electric nerve stimulation (TENS) [37,38], prolotherapy , botulinum toxin , hyaluronic acid  or acupuncture [4,14] in the prevention or treatment of TMD.
There seems to be NO EVIDENCE of the effectiveness of magnesium supplements and swishing of the essential oils in the mouth (“oil pulling”) in the treatment of TMD.
Surgical treatment can help in jaw fractures, chronic TMJ luxation, ankylosis or congenital abnormalities.
Unless an obvious organic abnormality has been found, AVOID treatments that permanently change the bite or jaw, such as crown and bridgework, orthodontics, occlusal adjustment, repositioning splints, surgery or implants, because they may not be necessary or effective and may even worsen the pain [10,12].
Prevention of TMD
To prevent pain, learn how to deal with stress. Accept personal and work challenges that bring peace to you and decline those that do not.
Avoid caffeinated drinks (coffee, tea, cola, energy drinks), chewing gum, hard-to-chew foods and extreme jaw movements (laughing, yawning, yelling, singing). Do not poke your chin forward during computer work and do not cradle the phone between the ear and shoulder or carry heavy bags over a shoulder.
Frequently Asked Questions
Do you always feel pain in TMD?
TMD is usually associated with pain but sometimes only with other symptoms, such as lockjaw, jaw clicking or fullness in the ears.
How long does TMD last?
TMD can last as long as the underlying cause (anxiety, rheumatoid arthritis, etc.) persists. The condition is rarely permanent.
Is TMD hereditary?
In most cases, TMD is an acquired condition. There are certain genetic predispositions, such as anatomical variants of the TMJ or genetic diseases, such as Marfan syndrome, which increase the risk of TMD.
What does temporomandibular arthralgia mean?
Pain in the temporomandibular joint.
Which specialist treats TMD?
Your primary doctor can perform a basic physical examination of your mouth, ear and jaw. Depending on the suspected cause the doctor can refer you to a dentist, orthopedist, neurologist or maxillofacial surgeon.
What is the cost of TMD surgery?
Surgery cost in the United States may vary greatly and can range from $300 to $70,000 [49,50]. Nonsurgical treatment can cost from $200 to $10,000 .
Can jaw exercises help in TMD?
Exercises may not be very helpful in TMD that results from anxiety or overuse of the chewing muscles. In these cases, prevention is more important. It is your doctor who can tell if and which exercises can help in your case.
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