Epidemiology of temporomandibular disorders: implications for the investigation of etiologic factors.

Epidemiology is the study of the distribution, determinants, and natural history of disease in populations. Epidemiology has several uses in addition to its traditional role of documenting the public health significance of a condition. Notably, epidemiologic methods and data can be used to identify and verify causes of disease. This article reviews the epidemiologic data on pain in the temporomandibular region, and on signs and symptoms associated with specific subtypes of temporomandibular disorders, with the aim of identifying possible etiologic factors for these conditions that deserve further study. Despite methodologic and population differences, several consistencies are apparent in the epidemiologic literature. Pain in the temporomandibular region appears to be relatively common, occurring in approximately 10% of the population over age 18; it is primarily a condition of young and middle-aged adults, rather than of children or the elderly, and is approximately twice as common in women as in men. This prevalence pattern suggests that etiologic investigations should be directed at biologic and psychosocial factors that are more common in women than in men, and diminish in older age groups. Most signs and symptoms associated with particular temporomandibular disorders (e.g., joint sounds, pain in the joint) also appear to be more prevalent in women than in men, although age patterns for these signs and symptoms are not as clear as for temporomandibular pain. The available data highlight the need for further research on etiologic factors associated with temporomandibular pain and with specific diagnostic subtypes of temporomandibular disorders.