Fluoride Research Analysis

Q: Why did governments decide to fluoridate water?

In the mid-20th century, governments introduced community water fluoridation as a strategy to address the widespread issue of dental decay, which posed a major public health challenge.[11] Observational research at the time showed that communities with naturally high fluoride levels in their water had significantly lower rates of tooth decay (dental cavities) than communities with lower levels,[12][13][14] and subsequent experimental research confirmed the beneficial effects of water fluoridation for reducing cavities and improving dental health.[9] This evidence supported community water fluoridation as a cost-effective measure for improving dental health across entire populations in both adults and children, offering widespread benefits regardless of an individual's income level or access to dental care.

Q: Should community water be fluoridated?

This is a controversial question. Tooth decay is a public health problem affecting many adults and children. But the need for community water to be fluoridated is debated.[1] There is evidence from observational research including 44,268 participants that fluoridation reduces levels of tooth decay and caries in children, compared to no fluoridation, by up to 35%. Fluoridation is linked with 15% more children with no decay in baby teeth and 14% more children with no decay in permanent teeth. However, most of this research is from before widespread use of fluoride toothpaste.[9] There is not enough evidence to know what would occur if fluoridation were removed in the present day.

Q: Does fluoride impact neurological development in children?

Although more research is needed to know for sure, it appears that excessive fluoride exposure is linked to poorer cognition in children; it’s important to note that community fluoridation in the United States and Canada is far below this level. A meta-analysis of 8 cross-sectional and cohort studies did not find that fluoride exposure via community water fluoridation affects IQ scores in children. However, high fluoride exposure (3.7 mg/L) from natural groundwater in certain geographical areas (e.g., parts of China and India) was associated with lower IQ when compared with lower fluoride exposure (0.7 mg/L). There was no difference in IQ between mean exposure to 0.9 mg/L fluoride when compared to 0.3 mg/L fluoride.[2] Another meta-analysis of 26 observational studies mostly conducted in China found that high fluoride exposure from water is associated with lower intelligence compared to normal fluoride exposure.[8] This data is limited by its observational nature and the presence of various confounding factors. For example, the impact of socio-economic status or exposure to environmental toxins was not able to be controlled.

Q: Why are certain geographical areas more prone to fluoride toxicity?

While Western countries like the United States intentionally add a small amount of fluoride to drinking water for dental health, some geographical locations have groundwater that is naturally excessively high in fluoride, and people who live in these areas have a greater risk of developing fluoride toxicity. In some regions of India and China, geothermal and volcanic activity has led to the formation of rocks that have high levels of fluoride. When these rocks are exposed to alkalinity and heat, fluoride is released into the soil and freshwater sources, resulting in high-fluoride food crops and drinking water. Fluoride does not have a taste, odor, or color, and since groundwater is not tested often, high fluoride exposure can go undetected for a long time. It is predicted that some countries in Central Africa are also at high risk for drinking water with excessively high fluoride.[10]

Q: How do fluoride varnishes work?

Fluoride varnish is a highly concentrated fluoride treatment applied to the surface of the teeth by dental professionals using a brush, cotton tip, or syringe-like applicator, typically 2 to 4 times per year in individuals who are at high risk of caries (dental cavities).[15][16] Fluoride varnishes form a temporary coating on the teeth that allows fluoride to be slowly released and absorbed into the enamel over time. This process helps reduce enamel demineralization (mineral loss) and promotes remineralization, repairing early tooth damage.[16] More specifically, during an acid attack (in which bacteria in plaque produce acids from sugars), fluoride moves with the acid from plaque into the tooth enamel, where it reduces mineral loss by decreasing the solubility of the enamel, increasing calcium and phosphate availability, and inhibiting the diffusion of acid into the enamel. As the pH normalizes after the acid attack, fluoride combines with calcium and phosphate in the saliva to rebuild and strengthen the enamel by forming fluorapatite, a mineral that is more resistant to future acid damage.[17] This dual action — reducing mineral loss and enhancing mineral gain — makes fluoride a powerful tool for preventing dental caries.

Marina Shkayeva

Fluoride

•Last Updated: December 17, 2024

Fluoride is a mineral found in bones and teeth. Fluoride is often used to strengthen enamel and prevent cavities. Small amounts of fluoride are added to public water supplies in some countries, a process known as water fluoridation.

Dosage

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Fluoride is most often used for

Marina Shkayeva, PharmD

•

Antonis Damianou, MSc

Nick Milazzo, MSc, MPH

•

Katie Jantz, RPh, MSc

Last Updated:December 17, 2024

Dosage Information
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Frequently asked questions
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References

What is fluoride?

Fluoride is the ionic form of the abundant element fluorine. It occurs in soil, rocks, and water, and is naturally present in food and drink. About 99% of the fluoride in the body is bound to calcified tissues (bones and teeth), and the rest is in the blood. Despite its presence in the body, it’s debated whether fluoride is an “essential” mineral, and there are no set dietary guidelines for fluoride.^[1] Fluoride is also found in many toothpastes and in some dietary supplements. While inadequate fluoride intake leads to tooth decay (dental caries), excessive intake can damage tooth enamel and cause other side effects. To prevent tooth decay, fluoridation of community water has been a practice since the 1960s in the United States.^[1] Currently, about 30 Western countries have fluoridation policies, but less than half have active community water fluoridation.^[3]

Why did governments decide to fluoridate water?

What are fluoride’s main benefits?

Fluoride’s claim to fame is its ability to stop and reverse tooth decay: when topically applied to the teeth (e.g., in toothpaste or water), it’s integrated into the structure of the enamel. It simultaneously inhibits demineralization and promotes remineralization of the tooth, as well as blocking the activity of plaque-forming bacteria.^[4] Toothpaste containing 1000 to 1250 ppm of fluoride prevents caries to a greater degree than non-fluoride toothpaste.^[5] Fluoride also plays a role in bone formation and has been used for preventing osteoporosis.^[1]

Should community water be fluoridated?

What are fluoride’s main drawbacks?

Excessive intake of fluoride (>5-6 mg/daily) can be toxic, and most commonly presents as dental fluorosis (mottled enamel with white/brown spots and pitting). Higher daily doses (10-25 mg/day) of fluoride can lead to skeletal fluorosis, an accumulation of fluoride in bone, which increases bone density, reduces joint mobility, and can lead to fractures and pain; such high doses can sometimes even lead to cardiac complications. Some evidence suggests that the neurological development of children may be stunted by high fluoride exposure, but more research is needed to be sure. Fluoride toxicity most often occurs due to excessive ingestion of fluoridated dental products and in areas with naturally elevated levels of fluoride in the groundwater (e. g., parts of China and India). In cases of fluoride toxicity, calcium is often used to minimize further absorption of fluoride.^[1]

Does fluoride impact neurological development in children?

Why are certain geographical areas more prone to fluoride toxicity?

How does fluoride work?

Fluoride (from drinking water, supplements, tea, or dental products) is absorbed by the small intestine, and about half is excreted via the kidneys. Absorbed fluoride in the blood can bind with apatite in bone and teeth, becoming fluorapatite. Blood and bone concentrations of fluoride are in equilibrium and are impacted by bone remodeling activity and age.^[1] Fluoride in toothpaste and mouthwash works locally in the mouth by getting integrated into the structure of the tooth, supporting remineralization of teeth (by speeding up uptake of minerals like calcium and phosphate from the saliva to make stronger crystals on the outer enamel), resisting demineralization by acidic substances in the mouth, and inhibiting the activity of plaque-forming bacteria.^[6]^[7] Fluoride can also be professionally applied as a gel or varnish, allowing fluoride to be released when the mouth becomes acidic, thereby providing longer-term protection to the enamel.^[5]

How do fluoride varnishes work?

What are other names for Fluoride?

Note that Fluoride is also known as:

Acidulated Phosphate Fluoride
Amine Fluoride
Silver Diamine Fluoride
Sodium Fluoride
Sodium Monofluorophosphate
Stannous Fluoride

Dosage information

Fluoride is consumed from foods, fluoridated water, toothpaste, and some dietary supplements. Apart from some teas, most foods do not contain a substantial amount of fluoride. There is no dietary reference intake (DRI) for fluoride, but adults consume less than about 0.5 mg daily. The maximum safe daily dose of fluoride is 4 mg in adult men and 3 mg in women.^[1] In Europe, a number of combination mineral supplements for bone health containing 0.95 mg of fluoride per dose have been on the market for 40 years without reported side effects.^[1]

In community drinking water, the concentration of fluoride to prevent tooth decay ranges between 0.5 and 1.1 mg/L. The US Public Health Service recommends a fluoride concentration of 0.7 mg/L, and the US Environmental Protection Agency set the maximum level as 4 mg/L. The World Health Organization (WHO) guideline recommends 1.5 mg/L fluoride in the drinking water.^[2]

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