Different studies have shown that the decrease in caries in industrialized countries in recent decades is based on the use of fluorides, with topical fluoride application being of primary importance, especially the use of fluoride-containing toothpaste. The following article presents the current status of research into the mechanism of action and reaction of fluorides. Reference is made to the latest systematic review articles and guidelines on the subjects of "Caries-reducing efficacy" and "Recommendations for fluoride use".