OBJECTIVE: To make recommendations, based on current evidence, for practising physicians and dentists on interventions for the prevention of dental caries in their patients. OPTIONS: Systemic fluoride administration, professionally administered fluoride, use of fluoride mouth rinses, fissure sealants, oral-hygiene practices, dietary practices, identification of groups at a high risk of dental caries, and early diagnosis and treatment. OUTCOMES: Reduced prevalence of dental caries and fluorosis, longer retention of teeth and lower treatment costs. EVIDENCE: Several MEDLINE searches were conducted for articles published from January 1980 to December 1992, including relevant review articles. VALUES: Relevant clinical findings were evaluated and categorized with the use of the evidence-based methods and values of the Canadian Task Force on the Periodic Health Examination. Recommendations were developed for each method of caries prevention, with reduced incidence of dental caries and improved prevalence of caries-free teeth given high values. BENEFITS, HARMS AND COSTS: The potential benefits of these measures in the long-term are a lower incidence of tooth decay, longer retention of teeth and prevention of fluorosis. The cost saving can be considerable for patients and insurers; however, implementation of some recommendations will be difficult, since the traditional preventive practices of dentists and dental hygienists are not easily changed. RECOMMENDATIONS: There is good evidence that the following manoeuvres are effective in preventing dental caries: use of dentifrices containing fluoride, fluoridation of drinking water, fluoride supplements for patients in areas where there is a low level (0.3 ppm or less) of fluoride in the drinking water, professionally applied topical fluoride and the use of fluoride mouth rinses for patients with very active decay or at a high risk of dental caries and selective use of professionally applied fissure sealants on permanent molar teeth. There is poor evidence that the following manoeuvres are effective in preventing dental caries: professionally applied topical fluoride and the use of fluoride mouth rinses for patients with a low risk of caries, toothbrushing (without a dentifrice containing fluoride) and flossing, cleaning of teeth by a dentist or dental hygienist before topical application of fluoride or at a dental visit and dietary counselling for the general population. There is good evidence to recommend against the use of over-the-counter fluoride mouth rinses by the general population. VALIDATION: These guidelines are compatible with those of the US Preventive Services Task Force. SPONSOR: These guidelines were developed and endorsed by the task force, which is funded by Health Canada. Major funding was provided by the Faculty of Dentistry of the University of Toronto, Toronto and the Faculty of Dentistry of Dalhousie University, Halifax.