Water Fluoridation for Dental Caries Prevention

Do community water fluoridation programs prevent dental caries?

Fluoridating water may result in a small reduction in tooth decay in children’s primary teeth, but its impact on permanent teeth remains unclear. Community water fluoridation may slightly decrease the proportion of children with “decayed, missing, or filled” primary and permanent teeth.¹ (Strength of Recommendation: B, inconsistent or limited-quality patient-oriented evidence.)

Dental caries, or cavities, are a significant public health issue, affecting approximately 60% to 90% of the global population. Community water fluoridation began in the United States in 1945 and is now practiced in approximately 25 countries.¹ It is widely regarded as a safe and effective means of reducing dental caries in children and adults. State and local governments determine whether to fluoridate water supplies. According to the Centers for Disease Control and Prevention (CDC) 2022 national water fluoridation statistics published in 2024 (prepared using water system data reported by states to the CDC Water Fluoridation Reporting System as of December 31, 2022), 62.8% of the US population had access to fluoridated water.² Fluoridated water availability varies widely among states, with less than one-third of people in Hawaii, New Jersey, Oregon, Montana, and Idaho having access.² Fluoridated water and fluoride toothpaste work synergistically to prevent cavities.

This Cochrane review updates a 2015 review, which primarily relied on studies conducted before the widespread use of fluoride toothpaste in the 1960s.³ The 2015 review found that community water fluoridation reduced caries in primary and permanent teeth in children. This updated review presents the most current evidence on the impact of community water fluoridation on dental caries through August 2023, though it does not include updates on fluorosis (a tooth condition due to excess fluoride intake during dental development) data, which remain current only through February 2015.¹ The updated review includes populations of all ages, with outcome measures such as changes in the number of decayed, missing, and filled primary and permanent teeth, the proportion of caries-free participants, dental fluorosis, and other potential adverse effects. A total of 157 nonrandomized studies were included, 155 of which were also part of the previous review. Twenty-one studies conducted in Europe, North America, South America, Australia, and Asia evaluated the impact of initiating water fluoridation programs on dental caries.

Two studies (n = 2,908) conducted after 1975 suggested that community water fluoridation still results in a trend toward decreased decayed, missing, or filled primary teeth over time; this conclusion was based on low-certainty evidence that was not statistically significant.¹ Four studies conducted after 1975 (n = 2,856) indicated that community water fluoridation may lead to a modest reduction in decayed, missing, or filled permanent teeth, but this result was also not statistically significant. Furthermore, based on two studies (n = 2,348) conducted after 1975, fluoride in drinking water may slightly increase the proportion of caries-free children regarding their primary dentition; this result was also not statistically significant. These low-certainty results suggest a 4% difference in caries within primary dentition and a 3% difference in caries within permanent dentition, although the findings include the possibility of no effect.