Water Fluoridation

Water fluoridation is the controlled addition of fluoride to public water supplies to reduce tooth decay, maintaining fluoride levels effective for cavity prevention either naturally or through supplementation; in the mouth, fluoride slows tooth enamel demineralization and enhances remineralization in early stage cavities, and defluoridation becomes necessary when natural fluoride levels exceed recommended limits. The World Health Organization recommends fluoride levels of 0.5 to 1.5 milligrams per liter depending on climate and other factors, and in the United States the recommended level has been 0.7 milligrams per liter since 2015, lowered from 1.2. Tooth decay affects sixty to ninety percent of schoolchildren worldwide, and fluoridation reduces cavities in children, with Cochrane reviews estimating reductions of thirty five percent in baby teeth and twenty six percent in permanent teeth when no other fluoride sources are available, though its efficacy in adults is less clear; in Europe and other regions, declining decay rates are instead attributed to topical fluorides and alternatives such as salt fluoridation and nano-hydroxyapatite. The United States was the first country to fluoridate water, and seventy two percent of its population drank fluoridated water as of 2022, while globally only about 5.4 percent of people receive fluoridated water, with the practice remaining rare in Europe outside Ireland and parts of Spain; the World Health Organization, the FDI World Dental Federation, and the United States Centers for Disease Control and Prevention endorse fluoridation as safe and effective at recommended levels, while critics question its risks, efficacy, and ethical implications.