PURPOSE The aim of this study was to evaluate the efficacy of three topical fluoride treatments to arrest initial root carious lesions. MATERIALS AND METHODS Forty patients participated in a randomised study. Of the 60 root carious lesions that were included, 20 were randomised for treatment with the Carisolv chemo-mechanical technique and the Duraphat (2.23% F) fluoride varnish, 20 with Duraphat alone and 20 with stannous fluoride solution (8%). The lesions were treated at baseline and after three and six months; a clinical evaluation was carried out on these occasions and after 1 year. RESULTS All but four lesions were categorised as arrested caries during the 1-year follow-up period: 18 in the Carisolv/Duraphat group and 19 each in the Duraphat and the stannous fluoride groups, respectively. There was a minor reduction in the mean size of the lesions of around 0.1 to 0.2 mm height and width and a moderate change in colour from a lighter to a darker appearance. No obvious differences were found between the groups. The mean percentage of mutans streptococci in plaque from all lesions was 3.5% at baseline, and it decreased to 1.8% during the year. The decrease was, however, not statistically significant, and no significant differences were found between the groups. CONCLUSIONS It can be concluded that the frequent topical application of fluoride could be a successful treatment for incipient root carious lesions, irrespective of the type of fluoride treatment used.