Since 1972, the dentures of 935 patients irradiated for head and neck carcinoma have been preserved after careful selection and according to well-defined criteria, using a prospective programme of daily applications of topical sodium fluoride gel. The results of 1-10 years follow-up are given. Four percent of the patients developed a diffuse dental decay and 1% a bone necrosis which can be related to the dental preservation. None of these complications occurred with careful patient selections nor when programme compliance was maintained. Post-irradiation dental extractions were performed in 29 cases with subsequent healing in all cases but one. The surgical technique of such extractions is described. In March 1980, a randomized protocol was activated to compare the use of the sodium fluoride gel to high content fluoride toothpaste (1350 ppm F-). Two hundred and twenty patients were entered. At 12-36 months follow-up, dental caries were observed in 3% of the patients receiving the fluoride gel as compared to 11% receiving the toothpaste (p = 0.1). However, none of the patients adhering to the programme instructions failed in either arm. Currently, it seems reasonable to state that preservation of teeth in irradiated patients should be the rule and not the exception, given good dental condition prior to treatment and patient cooperation. The 5 min daily application of fluoride gel is the most reliable method for prevention of post-irradiation dental caries. The twice daily use of high content fluoride toothpaste is a good alternative provided its limitations are well understood by the clinician and patient.