Many epidemiological studies have shown that the prevention of dental caries by fluoride is a basic and indispensable method to maintain and improve dental health. However, the countermeasures for maintenance of dental health and implementation of preventive programs for caries are still not satisfactory in Japan. In developed countries, it is thought that the prevalence of water fluoridation and use of fluoride-containing dentifrices are the primary factors responsible for the remarkable decrease in the prevalence of dental caries in children. Topical application of fluorides, especially fluoride mouth rinsing, has an extremely important role in Japan as compared with various other countries, because systemic application of fluorides, such as water fluoridation and use of fluoride tablets are not yet available in Japan. However, fluoride mouth rinsing has not become prevalent on a nationwide scale. Therefore, it is hoped that fluoride mouth rinsing will be enforced in more kindergartens, elementary schools, and junior high schools to contribute to the improvement of dental health in the future.