During 1997 and 1998 261 patients suffering from suspected focal diseases were investigated for the presence of persisting chronic inflammatory disorders in the oral cavity. In 83% of the patients pulp necrosis, chronic inflammation of the apical area and the periodontal tissues could be revelated. The most commonly diagnosed disorders were pulp necrosis, chronic apical periodontitis and periodontitis complicata respectively. Most frequently these diseases could be detected in chronic cardiac disorders, uveitis and dermatological diseases. In the future follow-up studies parallel with the elimination of the dental disorders monitoring of blood and serum parameters will be conducted in order to obtain data of th systemic effect of the persisting chronic dental diseases.