Water fluoridation is the controlled adjustment of fluoride to a public water supply to reduce tooth decay.
Fluoridated water contains fluoride at a level that is effective to prevent cavities.
Fluoridated water can occur naturally or by adding fluoride.
Fluoridation is normally accomplished by adding one of three compounds to the water: sodium fluoride, fluorosilicic acid, or sodium fluorosilicate.
Globally, 350 million people, which is only 5% of the world’s population including over 200 million Americans, consume fluoridated water.
In Europe, 98% of the population drinks unfluoridated water.
In the US, the dominant narrative is that water fluoridation, with a recommended concentration of 0.7 mg/L for all ages.
US Department of Health Human Services Federal Panel on Community Water: it is safe and effective.
Potential harms of exposure to fluoride, including low IQ, neurobehavioral deficits, and endocrine dysfunction.
Fluoride mineral occurs naturally.
Fluoride is released from rocks into the soil, water, and air.
All water has some fluoride content.
Usually, the fluoride level in water is not enough to prevent tooth decay.
Fluoride use has been proven to protect teeth from decay.
A constant low level of fluoride in the mouth works best to prevent cavities.
The health benefits of fluoride include having:
Less severe cavities.
Less need for fillings and removing teeth.
Less pain and suffering because of tooth decay.
Bacteria in the mouth produce acid when a person eats sugary foods, and it eats away minerals from the tooth’s surface, making the tooth weaker and increasing the chance of developing cavities.
Fluoride helps to rebuild and strengthen the tooth’s surface, the enamel.
Fluoridated water operates on tooth surfaces
In the mouth, it creates low levels of fluoride in saliva, which reduces the rate at which tooth enamel demineralizes.
Fluoridated water increases the rate at which it remineralizes in the early stages of cavities.
Water fluoridation prevents tooth decay.
Fluoridation keeps the tooth strong and solid.
Fluoride stops cavities from forming and can even rebuild the tooth’s surface.
Other fluoride-containing products, such as toothpaste, mouth rinses, and dietary supplements contribute to the prevention and control of tooth decay.
Community water fluoridation is the most cost-effective method of delivering fluoride to all, reducing tooth decay by 25% in children and adults.
Fluoride provides dental benefits to children and adults throughout their lives.
For children younger than age 8, fluoride helps strengthen permanent teeth that are developing under the gums.
For adults, drinking water with fluoride supports tooth enamel, keeping teeth healthy.
Nearly 73% of the United States served by community water systems has access to fluoridated water.
In 2019, a division of the U.S. Department of Health and Human Services evaluating of substances for potentially harmful human health effects, concluded that fluoride is presumed to be a cognitive neurodevelopmental hazard to humans.
The conclusion that higher fluoride exposure is associated with decreased IQ or other cognitive impairments in children, but lacked scientific support (2020).
The uncertainty about potential neurotoxicity effects of fluoride exposure persists.
Fluoride mostly helps tooth decay by topical means, mainly using fluoride toothpaste, which is adequately available in the US.
Fluoride exposure can be reduced by drinking spring water or through three filtering processes of reverse osmosis, deionizers, and activated alumina of filtrations.
Fluoridation provides the same dose of fluoride for all ages.
Fluoridation costs an average of about $1.11 per person-year.
Defluoridation is required when the naturally occurring fluoride level exceeds recommended limits.
A level of fluoride from 0.5 to 1.5 mg/L depending on climate, local environment, and other sources of fluoride is suggested.
Bottled water typically has unknown fluoride levels.
Fluoridation does not affect the appearance, taste or smell of drinking water.
Water fluoridation reduces cavities in children, but its efficacy in adults is less clear.
Most European countries have experienced substantial declines in tooth decay, though milk and salt fluoridation are widespread in lieu of water fluoridation.
Recent studies suggest that in industrialized nations, it may be unnecessary because topical fluorides are widely used, and caries rates have become low.
Although fluoridation can cause dental fluorosis, which is mild and usually not of public health concern.
No clear evidence of other adverse effects from water fluoridation.
Fluoride’s effects relate to the total daily intake of fluoride from all sources.
Fluoride in drinking water is typically the largest source, and other methods of fluoride therapy include fluoridation of toothpaste, salt, and milk.
Most authorities and health organizations find fluoridation as the most efficient method for community prevention of tooth decay.
European Commission finds no benefit to water fluoridation compared with topical use.
WF remains controversial as a public health measure.
Some countries and communities have discontinued fluoridation, while others have expanded it.
In most industrialized countries, tooth decay affects 60–90% of schoolchildren and the majority of adults.
Minorities and the poor in the US both have higher rates of decayed and missing teeth, and their children have less dental care.
The goal of water fluoridation is to prevent a chronic disease whose burdens particularly fall on children and the poor, and to bridge inequalities in dental health and dental care.
The recommended adequate intake
of fluoride from all sources is 0.05 mg/kg body weight per day for children, adults, pregnant and lactating women.
The recommended level of fluoride to 0.7 mg/ in community water systems and in
Fluoride naturally occurring in water can be above, at, or below recommended levels.
Rivers and lakes generally contain fluoride levels less than 0.5 mg/L.
Groundwater, in volcanic or mountainous areas, can contain as much as 50 mg/L of fluoride.
In most drinking waters, over 95% of total fluoride is the F− ion, and the magnesium–fluoride complex (MgF+) being the next most common.
High natural fluoride levels are associated with calcium-deficient, alkaline, and soft waters.
Defluoridation is needed when the naturally occurring fluoride level exceeds recommended limits.
Defluoridation occurs by
percolating water through activated alumina, bone meal, bone char, or tricalcium phosphate, or by coagulation with alum; or precipitation with lime.
Reverse osmosis filters remove 65–95% of fluoride, and distillation removes all fluoride, but pitcher or faucet-mounted water filters do not alter fluoride content.
Some bottled waters contain fluoride: if natural source waters have fluoride, or if water is sourced from a public supply which has been fluoridated.
Bottled water products labeled as de-ionized, purified, demineralized, or distilled have been treated in such a way that they contain no or only trace amounts of fluoride.
Fluoridation causes dental fluorosis, most of which is mild and not usually of aesthetic concern.
Fluoride may also prevent cavities in adults of all ages.
Stopping of community water fluoridation programs was typically followed by an increase in cavities.
Most countries experience substantial declines in cavities without the use of water fluoridation due to the introduction of fluoridated toothpaste and the large use of other fluoride-containing products, including mouthrinse, dietary supplements, and professionally applied or prescribed gel, foam, or varnish.
Adverse effects of fluoride depends on total fluoride dosage from all sources.
At recommended dosage, the only clear adverse effect is dental fluorosis.
Dental fluorosis can alter the appearance of children’s teeth during tooth development.
Dental fluorosis is generally mild and unlikely to represent any real effect on aesthetic appearance.
Mild or very mild dental fluorosis has been reported in 20% of the population, moderate fluorosis in 2% and severe fluorosis in less than 1%.
The critical period of exposure to fluoride is between ages one and four years.
Dental fluorosis risk ends around age eight.
Fluoridated water directly or indirectly responsible for dental fluorosis with an estimated 40% of risk and other sources, notably toothpaste, responsible for the remaining 60%.
In many industrialized countries the prevalence of fluorosis is increasing because of fluoride from swallowed toothpaste.
In the U.S. the decline in tooth decay was accompanied by increased fluorosis in both fluoridated and unfluoridated communities.
Fluoride has been reduced in in infant formulas, children’s toothpaste, water, and fluoride-supplement schedules.
Fluoridation has little effect on risk of bone fractures.
There is no clear association between fluoridation and cancer or deaths due to cancer, or for bone cancer and osteosarcoma.
When fluoride occurs naturally in water in concentrations well above recommended levels, water utilities in the developed world reduce fluoride levels to regulated maximum levels.
The World Health Organization recommends a guideline maximum fluoride value of 1.5 mg/L as a level at which fluorosis should be minimal.
If water fluoridation results in overfluoridation it can cause outbreaks of acute fluoride poisoning, with symptoms that include nausea, vomiting, and diarrhea.
Fluoride exerts interferes with the demineralization mechanism of tooth decay.
Tooth decay is an infectious disease: increased within dental plaque of bacteria such as Streptococcus mutans and Lactobacillus.
These organisms produce organic acids when carbohydrates, especially sugar, are eaten.
When enough acid is produced to lower the pH below 5.5, the acid dissolves carbonated hydroxyapatite, the main component of tooth enamel, in a process known as demineralization.
Some of the mineral loss can be recovered, or remineralized, from ions dissolved in the saliva.
Cavities result when the rate of demineralization exceeds the rate of remineralization, typically in a process that requires many months or years.
Hydroxyapatite enamel crystal is demineralized by acid in plaque and becomes partly dissolved crystal.
Demineralized enamel crystal is remineralized by fluoride in plaque to become fluorapatite-like coating on remineralized crystal
All fluoridation processes, including water fluoridation, create low levels of fluoride ions in saliva and plaque fluid, providing a surface effect.
Individuals exposed to fluoridated water may experience rises of fluoride concentration in saliva several times during a day.
Fluoride does not prevent cavities.
Fluoride can control,the rate at which caries develop.
Fluoride ions present in plaque fluid along with dissolved hydroxyapatite, and the pH is higher than 4.5 is present, a fluorapatite-like remineralized veneer is formed over the remaining surface of the enamel;
Reminetalized veneer is more acid-resistant than the original hydroxyapatite, and is formed more quickly than ordinary remineralized enamel would be.
Cavity prevention effects of fluoride are mostly due to surface effects.
Fluoride’s effects are dependent on the total daily intake of fluoride from all sources.
About 70–90% of ingested fluoride is absorbed into the blood.
80–90% of absorbed fluoride is retained in infants, with the rest excreted, mostly via urine.
Adults retain about 60% of fluoride.
About 99% of retained fluoride is stored
in calcium-rich areas: bone, teeth, and other calcium-rich sites, where excess quantities can cause fluorosis.
Drinking water is typically the largest source of fluoride, but In many industrialized countries swallowed toothpaste is the main source of fluoride exposure in unfluoridated communities.
Other sources of fluoride include dental products other than toothpaste, directly from the air due to the use of high-fluoride soft coal for cooking and drying foodstuffs indoors.
High fluoride levels have been found in other foods, including barley, cassava, corn, rice, taro, yams, and fish protein concentrate.
Dietary Reference Intakes for fluoride: Adequate Intake values range from 0.01 mg/day for infants aged 6 months or less, to 4 mg/day for men aged 19 years and up.
The Tolerable Upper Intake Level is 0.10 mg/kg/day for infants and children through age 8 years, and 10 mg/day thereafter.
It is estimated is that an adult in a temperate climate consumes 0.6 mg/day of fluoride without fluoridation, and 2 mg/day with fluoridation.
A tube applying toothpaste to a toothbrush.
Fluoride toothpaste is effective against cavities. It is widely used, but less so among the poor.
Opinions on the most effective method for community prevention of tooth decay are mixed: water fluoridation is the most effective means of achieving fluoride exposure that is community-wide; No obvious advantage appears in favor of water fluoridation compared with topical prevention; fluoride therapies are also effective in preventing tooth decay, including fluoride toothpaste, mouthwash, gel, and varnish, and fluoridation of salt and milk. and dental sealants.
Dental sealants are estimated to prevent cavities ranging from 33% to 86%, depending on age of sealant and type of study.
Fluoride toothpaste is the most widely used fluoride treatment.
Fluoride toothpaste is considered the main reason for the decline in tooth decay in industrialized countries.
Toothpaste relies on individual and family behavior, and its use is less likely among lower economic classes, and in low-income countries it is unaffordable for the poor.
Fluoride toothpaste prevents about 25% of cavities in young permanent teeth.
Fluoride toothpaste’s effectiveness is improved if higher concentrations of fluoride are used, or if toothbrushing is supervised.
Fluoride mouthwash and gel are equally as effective as fluoride toothpaste.
Fluoride varnish prevents about 45% of cavities.
Brushing with a nonfluoride toothpaste has little effect on cavities.
Salt fluoridation has the same effectiveness as that of water fluoridation.
Salt fluoridation is widespread.
Fluoride concentrations in salt range from 90 to 350 mg/kg.
An optimal concentration of fluoride in salt is around 250 mg/kg.
It is estimated that sealants decreased cavities by about 60% overall, compared to about 18–50% for fluoride.
Communities have discontinued water fluoridation in some countries.
Israel stopped mandating fluoridation, estimating 1% of the water is used for drinking, while 99% of the water is intended for other uses such as industry, agriculture, toilets.
There is scientific evidence that fluoride in large amounts can lead to damage to health.
Fluorosis occurs before tooth eruption.