Prevalence of temporomandibular disorder ( TMD )

The Nuprin Pain Report showed that the major health complaint in the USA was pain (88%)18 . In the same US population, recurrent or persistent orofacial pain (not including ‘toothache’) has been estimated to occur in 6-12% of people, with a similar figure of 5% of the population in the Netherlands. The variability in the US figures is probably related to the respective investigators adopting different diagnostic criteria in achieving a firm diagnosis of temporomandibular disorder (TMD). Other names ascribed to this condition include Costen’s syndrome, temporomandibular joint dysfunction, and craniomandibular disorder. TMD is characterised by a complex of signs and symptoms, with orofacial pain as a main symptom. TMD is the most common orofacial pain disorder but its prevalence varies between studies, due likely to age-related differences in the groups analysed. One survey reported the prevalence of TMD symptoms or signs to occur in 70-80% of young adults. TMD is usually associated with a predilection for females in the 18-35 year age group. In this group, TMD is usually of limited duration (days to weeks) and it is often recurrent because ‘stress’ is a prime causal factor. Nearly 2% of the population seek treatment for their symptoms. However, it should be noted that Vickers et al. have shown that TMD occurs in another targeted age group (45-60 years); patients referred to a medical multidisciplinary pain centre reported chronic ‘persistent’ pain, in contrast to ‘recurrent’ pain. No definitive reason has been established for ‘persistent’ pain, although there is compelling evidence to indicate that one cause is muscle spasm secondary to neuropathic orofacial pain, and thus, the consequent development of a TMD.