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Conditions InDepth: Temporomandibular Disorders (TMD)

by Rosalyn Carson-DeWitt, MD

Temporomandibular disorders (TMD) involves the two joints that attach the lower jaw (mandible) to the skull. These two joints open and close the mouth, and are located directly in front of your ears.

Adult Skull Showing Temporomandibular Joint

Adult Skull Showing TMJ and Muscles
Copyright © Nucleus Medical Media, Inc.

You may have TMD if:

  • The temporomandibular joints (TMJ) are chronically inflamed and sore.
  • The muscles that work the temporomandibular joints are regularly in spasm.
  • The cushioning disc that should rest between the temporomandibular joint and the skull becomes worn out or displaced.

Researchers do not exactly know what causes TMD. Some people have had accidents or injuries involving their jaw, but many others have had no such incident. Some of the possible causes include:

  • Grinding the teeth or clenching the jaw in response to stress, known as bruxism
  • Arthritis of the temporomandibular joint
  • History of injury or trauma to the joint
  • Facial bone defects
  • Misalignments of the jaw or of the bite

Enlargement of TMJ With Jaw Open

Enlargement of TMJ with Open Jaw
Copyright © Nucleus Medical Media, Inc.

TMD symptoms may originate within the joint itself or from the muscles that surround the joint. The treatment of these two variants of TMD may differ.

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References:

Diatchenko L, Slade GD, et al. Genetic basis for individual variations in pain perception and the development of a chronic pain condition. Hum Mol Genet. 2005;14:135-143.
Nackley AG, Tan KS, et al. Catechol-O-methyltransferase inhibition increases pain sensitivity through activation of both beta(2)- and beta(3)-adrenergic receptors (published electronically ahead of print). Pain. Nov 3, 2006.
Siccoli MM. Facial pain: a clinical differential diagnosis. Lancet Neurology. 2006;5:257-267.
Temporomandibular joint (TMJ) dysfunction. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php. Updated November 27, 2012. Accessed April 5, 2013.
TMJ. American Academy of Otolaryngology—Head and Neck Surgery website. Available at: http://www.entnet.org/. Updated December 2010. Accessed April 5, 2013.
TMJ. American Dental Association Mouth Healthy website. Available at: http://www.mouthhealthy.org/en/az-topics/t/tmj.aspx. Accessed April 5, 2013.
TMJ (temporomandibular joint and muscle disorders). National Institute of Dental and Craniofacial Research website. Available at: http://www.nidcr.nih.gov/OralHealth/Topics/TMJ. Updated March 21, 2013. Accessed April 5, 2013.
Last reviewed February 2013 by Peter Lucas, MD; Brian Randall, MD
Last Updated: 4/5/2013