Editing Temporomandibular joint dysfunction (section)

==Epidemiology==

TMD mostly affects people in the 20 – 40 age group,<ref name="Guo 2009" /> and the average age is 33.9 years.<ref name="Edwab 2003" /> People with TMD tend to be younger adults,<ref name="Medscape reference" /> who are otherwise healthy. Within the catchall umbrella of TMD, there are peaks for disc displacements at age 30, and for inflammatory-degenerative joint disorders at age 50.<ref name="Manfredini 2011" />

About 75% of the general population may have at least one abnormal sign associated with the TMJ (e.g. clicking), and about 33% have at least one symptom of TMD.<ref name="Wright 2010" /> However, only in 3.6–7% will this be of sufficient severity to trigger the individual to seek medical advice.<ref name="Wright 2010" />

For unknown reasons, females are more likely to be affected than males, in a ratio of about 2:1,<ref name="Edwab 2003" /> although others report this ratio to be as high as 9:1.<ref name="Wright 2010" /> Females are more likely to request treatment for TMD, and their symptoms are less likely to resolve.<ref name="Wright 2010" /> Females with TMD are more likely to be [[nulliparous]] than females without TMD.<ref name="Scully 2008" /> It has also been reported that female [[American English|caucasians]] are more likely to be affected by TMD, and at an earlier age, than female [[African American]]s.<ref name="Medscape reference" />

According to the most recent analyses of epidemiologic data using the RDC/TMD diagnostic criteria, of all TMD cases, group I (muscle disorders) accounts for 45.3%, group II (disc displacements) 41.1%, and group III (joint disorders) 30.1% (individuals may have diagnoses from more than one group).<ref name="Manfredini 2011" /> Using the RDC/TMD criteria, TMD has a prevalence in the general population of 9.7% for group I, 11.4% for group IIa, and 2.6% for group IIIa.<ref name="Manfredini 2011" />

The highest prevalence of TMD (regardless of type) is in South America at 47%, followed by Asia at 33%, Europe at 29%, and North America at 26%.<ref name="ReferenceA"/>