Temporomandibular disorders =========================== * Eric T. Stoopler * Thomas P. Sollecito ## Temporomandibular disorder is regarded as a complex medical disorder, often with a multifactorial cause Temporomandibular disorder (TMD) is a diagnostic term describing a wide variety of disorders associated with the temporomandibular joint complex (bone, muscles, cartilage, and/or ligaments), with a high prevalence rate (up to 40%–75%) in a general population of having at least sign of the disorder.1 Based on evidence from multiple epidemiologic and experimental studies, as well as clinical trials, the diagnosis and treatment of TMD may be most appropriately conceptualized within the biopsychosocial medical model of disease.2 ![Figure1](http://www.cmaj.ca/https://www.cmaj.ca/content/cmaj/185/4/324/F1.medium.gif) [Figure1](http://www.cmaj.ca/content/185/4/324/F1) Image courtesy of © 2013 Thinkstock ## Otologic symptoms are common indicators of temporomandibular disorder Based on a prospective clinical study, otologic complaints such as otalgia, tinnitus, vertigo and muffling have reportedly higher prevalence in patients with TMD than in controls.3 ## Clicking of the temporomandibular joint that is otherwise asymptomatic often does not require active treatment Clicking of the temporomandibular joint (a common finding in a general population) is usually attributed to an articular disc disorder within the temporomandibular joint complex.4 A longitudinal study involving patients with an asymptomatic click failed to show a significant risk for long-term complications.4 ## Most cases are not substantially influenced by dental occlusion Although this finding is controversial, multiple systematic reviews, epidemiologic and case–control studies have shown that the influence of occlusion as a cause of temporomandibular disorder is low.5 ## Centrally and peripherally acting disorders can significantly affect prognosis As seen in multiple clinical epidemiologic studies, both centrally acting conditions, such as fibromyalgia and anxiety or depression, and peripherally acting conditions, such as trauma and postural tension, have been associated with delayed or incomplete recovery despite conventional treatments.6 Such conditions are also associated with increased risk of progression of temporomandibular disorders from acute to chronic status.6 *CMAJ* invites submissions to “Five things to know about …” Submit manuscripts online at [http://mc.manuscriptcentral.com/cmaj](http://mc.manuscriptcentral.com/cmaj) ## Footnotes * **Competing interests:** Eric Stoopler receives royalties from the American Dental Association (ADA). Thomas Sollecito is a consultant for the ADA Council on Scientific Affairs; he has received payment for manuscript preparation from the Compendium of Continuing Education in Dentistry. Both authors are members of the executive committee and board of trustees of the American Academy of Oral Medicine. No other competing interests were declared. * This article has been peer reviewed. ## References 1. Scrivani SJ, Keith DA, Kaban LB. Temporomandibular disorders. N Engl J Med 2008;359:2693–705. [CrossRef](http://www.cmaj.ca/lookup/external-ref?access_num=10.1056/NEJMra0802472&link_type=DOI) [PubMed](http://www.cmaj.ca/lookup/external-ref?access_num=19092154&link_type=MED&atom=%2Fcmaj%2F185%2F4%2F324.atom) [Web of Science](http://www.cmaj.ca/lookup/external-ref?access_num=000261757300009&link_type=ISI) 2. Suvinen TI, Reade PC, Kempainnen P, et al. 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