The number of patients treated on account of tumourous diseases is steadily rising. Patients owe to comprehensive oncological treatment not only improvement of the prognosis of the disease and a longer survival period but also cure. Along with more effective treatment there are also more complications. Patients with tumours in the region of head and neck can suffer from a number of complications. The paper deals with damage of hard dental tissues, causes and prevention of this damage.

        Key words: radiotherapy – chemotherapy – radiation caries – xerostomia – fluorides – chlorhexidine – artificial saliva