With a questionnaire addressed to general dental practitioners in Sweden, the Swedish Council on Technology Assessment in Health Care launched a project group in 1999 to systematically review and evaluate the existing literature on various caries preventive methods. The aim of this article was to report findings concerning the caries preventive effect of fluoride toothpastes in various age groups, with special emphasis on fluoride concentration and supervised versus non-supervised brushing. A systematic search in electronic databases for articles published between 1966 and April 2003 was conducted with the inclusion criteria of a randomized or controlled clinical trial, at least 2 years follow-up and caries increment in the permanent (deltaDMFS/T) or primary (deltadmfs/t) dentition as endpoint. Out of 905 articles originally identified, 54 met the inclusion criteria. These studies were assessed independently by at least two reviewers and scored A-C according to predetermined criteria for methodology and performance. The measure of effect was the prevented fraction (PF), expressed as percent. The results revealed strong evidence (level 1) (i) for the caries preventive effect of daily use of fluoride toothpaste compared to placebo in the young permanent dentition (PF 24.9%), (ii) that toothpastes with 1,500 ppm of fluoride had a superior preventive effect compared with standard dentifrices with 1,000 ppm F in the young permanent dentition (PF 9.7%), and (iii) that higher caries reductions were recorded in studies with supervised toothbrushing compared with non-supervised (PF 23.3%). However, incomplete evidence (level 4) was found regarding the effect of fluoride toothpaste in the primary dentition. In conclusion, this review reinforced the importance of daily toothbrushing with fluoridated toothpastes for preventing dental caries, although long-term studies in age groups other than children and adolescents are still lacking.