Water fluoridation
Health and dental organizations worldwide have endorsed its safety and effectiveness. Its use began in 1945, following studies of children in a region where higher levels of fluoride occur naturally in the water. Further research showed that moderate fluoridation prevents tooth decay.
Hans Rudolf Mühlemann
During his years in the United States, Mühlemann had learned that caries incidence could be significantly reduced through fluoridation of the communal water supply. The assumption at that time was that fluoride by way of the blood vascular system would be incorporated into tooth substance during tooth development, and positively affect caries resistance. Mühlemann was able to demonstrate that fluoride was also effective when applied topically after tooth eruption; this led him to the development of fluoride-containing dentifrice and mouthwash, and also to the fluoridation of table salt. He created a Caries Research Station led by Klaus G. König, who was called to a professorship in Nijmegen, the Netherlands, in 1968.