Abstract The most common mental disorder, depression, is internationally acknowledged as a considerable public health problem, major depression being one of the leading causes of premature mortality and disability in the world (Murray & Lopez 1996).

Besides its associations with disturbances in psychological and social functioning, depression is also associated with various biological alterations. Accordingly, extensive research has been conducted to link depression with several somatic diseases. The relationship between depression and oral health is still obscure, however.

This study was carried out to investigate the relationship of depressive symptoms with oral health and related factors in 55-year-old inhabitants of Oulu, 780 of whom participated. Depressive symptoms were measured with the Zung Self-Rating Depression Scale (ZSDS). A high rate of depressive symptoms was associated with symptoms of temporomandibular disorders (TMD), the subjective sensation of dry mouth, and high counts of salivary lactobacilli. An uncertain association was demonstrated between depressive symptoms and abundant growth of salivary mutans streptococci and the presence of yeasts in saliva. Depressive symptoms were associated with edentulousness in a subgroup of men who had never smoked. The dentate women with high rates of depressive symptoms did not consider it equally important to preserve their natural teeth as did the dentate women with fewer depressive symptoms. They also consumed sweets, snacks, and soft drinks more often, and a longer time had elapsed since their last visit to a dentist. No associations between depressive symptoms and periodontal pocketing or dental caries could be demonstrated in this cross-sectional study.

It is suggested that depression should be considered as a possible underlying factor when treating patients with TMD symptoms and complaints of oral dryness. Furthermore, considering the discovered association between depressive symptoms and microbial growth, the possibility of an increased risk for impaired oral health among depressed persons is emphasized.