Dental symptoms, oral medicine and psychiatric and psychologic problems have strict relationships in several domains. Behavior and behavioural problems (deficient oral hygiene, lack of regular dental control, dependence of nicotine or alcohol, etc.) as well as certain psychiatric diseases influence the patients' dental state to a great extent. There are further problems determined by the different types of anxiety, fear and bad previous experiences which have an impact on people's attitudes towards dental treatment and the development of hygienic habits. Dentists' psychologic and psychiatric knowledge can have a considerable contribution to the reduction of the patients' anxiety, furthermore to an appropriate treatment, by the recognition of the underlying psychiatric disease.