Japan: 40 Years of Falling Tooth Decay—but No Fluoridation

Japan has maintained a stunning long-term decline in rates of tooth decay—without water fluoridation.

A new study in the journal BMC Health looks at Japan as a “natural social experiment” on the effects of limited fluoride exposure in children.

Children’s Health Defense reports, “Using decades of national dental survey data, the study found that average rates of tooth decay among Japanese 12-year-olds fell steadily over roughly 40 years.

“Levels dropped from a peak national Decayed, Missing, and Filled Teeth (DMFT) index score of 4.75 in 1984 to just 0.53 in 2023—’well below levels historically reported in populations exposed to systemic fluoride through community water fluoridation,’ according to the study. DMFT is the standard international measure of decayed, missing and filled teeth.”

This happened without fluoridation and without the availability of high-fluoride toothpaste, which only arrived in Japan in 2017 and was not recommended for schoolchildren until 2023.

The study clearly shows that nutrition, behavior and broader public-health measures are effective in maintaining high levels of oral health in children.

Water-fluoridation remains a controversial issue in the US, despite a landmark judicial verdict against the EPA in 2024 that found optimal fluoridation levels in water posed an “unreasonable risk” of reduced IQ in children under the Toxic Substances Control Act.

That decision was overturned last month by an appeals court.

No broad federal ban or mandate has been brought in by Health Secretary Robert F. Kennedy Jr., despite his well-established opposition to fluoridation.

Instead, there are local bans, including statewide bans in Utah and Florida, and more than 60 localities and communities have enacted their own bans.