The Claim: Water fluoridation reduces cavities by 25%
The Source: The Center’s For Disease Control (CDC)
The CDC’s claim of 25% reduction in cavities is based on outdated, low-quality studies and ignores the most recent, highest-quality studies that show fluoridation no longer reduces cavities by more than a tiny amount, if at all.
The CDC declares water fluoridation “reduces cavities by about 25% in both children and adults.” This is accepted without question by most media and virtually all organizations promoting fluoridation, led by the American Dental Association and the American Academy of Pediatrics.
But this statement is erroneous. It is based on just two outdated references.
Children
The CDC’s sole reference is an outdated 2015 Cochrane Collaboration review which said there was a 26% reduction in decayed teeth. But CDC omits the report’s major caveats:
“These results are based predominantly on old studies and may not be applicable today.” “The majority of studies (71%) were conducted prior to 1975 and the widespread introduction of the use of fluoride toothpaste . . . over 97% of the 155 (fluoridation) studies were at a high risk of bias, which reduces the overall quality of the results.”
The CDC fails to mention a 2024 update to the Cochrane review. The update analyzed 21 higher quality studies conducted after 1975, and found fluoridation reduces cavities by just 3%-4%, only 1 decayed tooth per 4 children. This meager benefit was not statistically significant and includes the possibility of zero benefit.
Consistent with the Cochrane 2024 findings, World Health Organization data comparing cavity rates for children in fluoridated versus non-fluoridated nations shows no difference whatsoever in the past 20 years:
Adults
The CDC’s sole reference is a 2007 study by Griffin et al., a meta-analysis of nine studies, each comparing cavity rates in high fluoride versus low fluoride areas. It reported:
“The prevented fraction for water fluoridation was 27%.”
The Full Truth: The CDC omitted this about Griffin (2007):
• Its studies were done in 1962-1992: 33 to 63 years ago.
• All had fluoridated water at levels above the current 0.7 mg/L; mostly 1.0 to 1.5 mg/L and one as high as 3.5 mg/L – making them irrelevant for measuring effectiveness at today’s level.
• Eight were low quality cross-sectional design and only one was a higher quality prospective design.
• Only one was blinded, so the dental examiners didn’t know who had fluoridated water. The eight others had a high risk of researcher bias favoring fluoridation.
The updated Cochrane 2024 review didn’t find a single study in adults that met even their lowest quality criteria.
The CDC also fails to mention the 2024 LOTUS study. It’s the largest, most statistically powerful study ever done, analyzing 6.4 million people in the UK’s National Health Service. It found only a miniscule 2% lower cavity rate in permanent teeth of adolescents and adults drinking fluoridated water, which amounts to only 1/5th of a cavity per person from living 10 years in a fluoridated area. The study described this as an “exceedingly small” difference.
Furthermore, the economic “benefit” was less than the cost of a coffee a year, even when no capital or financing costs of fluoridation were considered. When those are included, fluoridation represents a net loss of money.
The newest studies show fluoridation no longer provides any meaningful reduction in cavities.
References:
CDC Oral Health: Community Water Fluoridation Facts
Website: https://www.cdc.gov/oral-health/data-research/facts-stats/fast-facts-community-water-fluoridation.html (Accessed April 30, 2025)
Iheozor-Ejiofor et al, Water fluoridation for the prevention of dental caries, Cochrane Database Systematic Review,
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010856.pub2/abstract?cookiesEnabled June 18, 2015
Iheozor-Ejiofor et al, Water fluoridation for the prevention of dental caries, Cochrane Database Systematic Review: https://pubmed.ncbi.nlm.nih.gov/39362658/ October 4, 2024
World Health Organization data: Collaborating Centre for Education, Training, and Research in Oral Health, Malmo University, Sweden: CAPP: Oral Health Country/Area Profile Project,
Griffin et al, Effectiveness of fluoride in preventing caries in adults, Journal of Dental Research,
https://journals.sagepub.com/doi/10.1177/154405910708600504, May, 2007
Moore et al, How effective and cost-effective is water fluoridation for adults and adolescents? The LOTUS 10-year retrospective cohort study, Community Dentistry and Oral Epidemiology,
https://onlinelibrary.wiley.com/doi/10.1111/cdoe.12930, January 8, 2024