Clinical signs indicative of temporomandibular disorders in adults: time trends and associated factors.

The study aimed to examine possible time trends in the prevalence of clinical signs indicative of temporomandibular disorder (TMD) in an adult population, to analyse possible associations between TMD signs and associated factors and to estimate the need for TMD treatment. Three independent, stratified and randomly selected samples of around 100 individuals in the age groups of 20, 30, 40, 50, 60 and 70 years participated in the Jönköping studies in 1983,1993 and 2003. The study material consisted of 1,693 subjects who, after answering a questionnaire and being interviewed about the presence of TMD symptoms, were clinically examined in terms of the presence of TMD signs according to the Clinical Dysfunction Index (Di) by Helkimo. Associations between clinical signs and the Di as dependent variables and each of the independent variables of age group, gender, reported bruxism, trauma, self-perceived healthiness and the year of investigation were analysed in binary logistic regression models. Estimates of the need for TMD treatment were based on the presence of a combination of severe symptoms and clinical signs. The prevalence of severely impaired jaw movement capacity, relating to horizontal movements, had increased in 2003. The prevalence of muscle pain and temporomandibular joint pain upon posterior palpation was found to vary statistically significantly between 1993 and 2003. Gender differences were noted in these changes overtime. Female gender, advancing age, awareness of bruxism, self-perceived health impairment and the wearing of complete dentures were associated with TMD signs and a higher degree of clinical dysfunction. The estimated need for TMD treatment increased from 5% in 1983 to 8% in 2003 and was higher in women than in men. In conclusion, the results indicate that the prevalence of some TMD signs and of estimated treatment need increased during the period 1983-2003.