Fluoride Action Network

Tooth Decay

“The magnitude of [fluoridation's] effect is not large in absolute terms, is often not statistically significant and may not be of clinical significance.” - Ontario Ministry of Health and Long Term Care (1999).


The addition of fluoride to water for the purpose of preventing tooth decay began in the 1940s on the mistaken premise that fluoride needs to be swallowed to be effective. As researchers have since shown, the fluoride’s benefit comes primarily from topical application, not ingestion. There is no need, therefore, to ever swallow fluoride. While fluoridation advocates now claim that fluoridated water provides an effective topical application to teeth, current data shows no meaningful difference in tooth decay between areas with, and without, fluoridated water.

in this section:

  • Topical vs. Systemic Effects: Learn why dental researchers now overwhelmingly agree that fluoride’s primary benefit to teeth comes from topical contact, not ingestion.
  • Tooth Decay in F vs. NF Countries: See World Health Organization data showing tooth decay rates have declined at the same steep rate in non-fluoridated countries, as they have in fluoridated countries.
  • Modern Fluoridation Studies: Learn 7 quick facts about modern fluoridation studies, including the results of the largest dental health survey ever conducted in the U.S., and the ongoing NIH-funded multimillion dollar study on the relationship between total fluoride intake and tooth decay. 
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