Study: Japan Demonstrates Nice Teeth Can Be Achieved with Limited Fluoride

A study by Professor Emeritus Y. Yamashita et al titled “A 40-year decline in permanent-tooth caries among 12-year-olds in Japan in the absence of systemic fluoride-based prevention: public health implications” published unedited on 18 May 2026 demonstrates that nice teeth can be achieved with limited fluoride.

The paper is about 22 pages, with the main text at about 15 pages. The remaining are acknowledgements, references and figures.

The data was obtained from the Ministry of Education’s School Dental Health Survey which contains Decayed, Missing, and Filled Teeth (DMFT) stats from the 1950s and onwards.

National sugar-availability statistics were obtained from the Agriculture & Livestock Industries Corporation (ALIC) and work done by H. Miyazaki and M. Morimoto, which was taken from the Japan Sugar Refiners Association.

From the 1950s until the early 1980s, dental caries increased in children. But then

…Japan experienced a remarkably smooth and continuous decline. Mean DMFT fell below 1.0 after 2015 and reached 0.53 in 2023, with no evidence of reversal or plateau at any point across four decades.

This figure of 0.53 is far below high-fluoride communities.

Figure 1: Dental caries trends among 12-year-olds in Japan, 1950–2023. Gray dots show the proportion of children with ≥1 decayed, missing, or filled permanent tooth (DMFT ≥1), based on national school dental health surveys. Black dots connected by a solid line show the national mean DMFT index.

During this same 40-year period, Japan had no community water fluoridation, and the most widely recommended children’s toothpastes contained 500 ppm fluoride—a concentration shown in systematic reviews to provide only limited caries-preventive effects in early childhood. High-fluoride toothpaste (1,500 ppm) became widely accessible only after 2017, and had not been recommended for children under 14 years of age until 2023—a point well after Japan’s major decline had already occurred.

In other words, this decline in DMFT cannot be attributed to water fluoridation and only in part can it be attributed to fluoride in toothpaste, especially when even “lower-fluoride products did not exceed a 90% market share until the early 2000s”.

A likely contributing factor is the drastic change in the annual per-capita sugar consumption, which “decreased by over 30% since its peak around 1975”. However, this somewhat stabilized to a slower and steadier decrease since the 1980s. Therefore, this decrease in sugar intake does not totally account for the continuing decline in DMFT.

The author discusses other factors such as parental influence, feeding practices and access to dental care at an early age. In short, dental health can be improved by taking a holistic approach rather than merely fluoridation.

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