Water fluoridation is the careful addition of fluoride to public water supplies to help reduce tooth decay. Fluoridated water keeps fluoride levels that are helpful for preventing cavities, whether the fluoride comes naturally or is added. In the mouth, fluoride helps protect tooth enamel by slowing the loss of minerals and helping to restore them in early cavities. Defluoridation is needed when natural fluoride levels in water are too high. The World Health Organization (WHO) suggests fluoride levels between 0.5 and 1.5 mg/L, depending on climate and other factors. In the U.S., the recommended level has been 0.7 mg/L since 2015, which is lower than the previous level of 1.2 mg/L. Bottled water often has fluoride levels that are not clearly known.
Tooth decay affects 60–90% of schoolchildren worldwide. Fluoridation helps reduce cavities in children, with studies showing a 35% reduction in baby teeth and a 26% reduction in permanent teeth when no other fluoride sources are used. However, its effectiveness in adults is less clear. In Europe and other areas, lower decay rates are linked to topical fluorides and other methods like adding fluoride to salt or using nano-hydroxyapatite.
The United States was the first country to use water fluoridation, and 72% of its population drinks fluoridated water as of 2022. Globally, 5.4% of people have access to fluoridated water, though this practice is uncommon in Europe except in Ireland and parts of Spain. The WHO, FDI World Dental Federation, and the U.S. Centers for Disease Control and Prevention support fluoridation as safe and effective when used at recommended levels. Some people question its risks, how well it works, and whether it is ethical.
Goal
The goal of water fluoridation is to stop tooth decay by changing the amount of fluoride in public water supplies. Tooth decay is one of the most common long-term health problems around the world. While it is not usually deadly, it can cause pain and make it hard to eat, speak, or look at someone's face. It also affects how people are accepted by others and greatly harms the quality of life for children, especially those from families with low income. In most developed countries, about 60% to 90% of schoolchildren and most adults have tooth decay. Although this problem is less common in some African countries, it is expected to grow there because of changes in food habits and less fluoride in the environment. In the United States, people from minority groups and those with low incomes have higher rates of tooth decay, and their children often receive less dental care. Once a cavity forms, the tooth may need many repairs over time, with most dental fillings lasting between 9 and 14 years. Oral health problems are the fourth most costly disease to treat. The reason for adding fluoride to water or salt is similar to adding iodine to salt to prevent a condition that affects the thyroid gland and causes swelling in the neck.
Water fluoridation aims to prevent a health problem that mainly affects children and people with low incomes. Another goal is to reduce differences in dental health and access to dental care. Some research shows that fluoridation may help reduce gaps in oral health between wealthy and poor people, but the evidence is not strong. There is no scientific proof that fluoride gives more time for dental treatment by slowing decay or makes treatment easier by causing cavities to form in certain parts of the teeth. Other studies have found that there is not enough evidence to say if fluoridation reduces differences in oral health among groups.
Health and dental groups worldwide support the safety and effectiveness of fluoridation when used at proper levels. Fluoridation started in 1945 after studies showed that children living in areas with naturally high fluoride levels in water had less tooth decay. Later research proved that adding fluoride at moderate levels helps prevent tooth decay.
Implementation
Fluoridation does not change the look, taste, or smell of drinking water. It is done by adding one of three compounds to water: sodium fluoride, fluorosilicic acid, or sodium fluorosilicate.
Sodium fluoride (NaF) was the first compound used and is the standard for comparison. It is a white, odorless powder or crystal. The crystal form is preferred when handled by hand because it reduces dust. It is more expensive than other compounds but is easier to use and often chosen by smaller water companies. It is dangerous if swallowed or inhaled in large amounts.
Fluorosilicic acid (H₂SiF₆) is the most common additive for fluoridation in the United States. It is a liquid made during the production of phosphate fertilizer. It is usually 23–25% strong and is inexpensive. However, shipping it can be costly because it contains a lot of water. It is also called hexafluorosilicic acid, hydrofluosilicic acid, and silicofluoric acid.
Sodium fluorosilicate (Na₂SiF₆) is the sodium form of fluorosilicic acid. It is a powder or fine crystal that is easier to ship than fluorosilicic acid. It is also called sodium silicofluoride.
These compounds are chosen because they dissolve easily, are safe, are available, and are inexpensive. A 1992 survey found that 63% of U.S. public water systems used fluorosilicic acid, 28% used sodium fluorosilicate, and 9% used sodium fluoride.
Fluoride naturally found in water can be above, at, or below recommended levels. Rivers and lakes usually have less than 0.5 mg/L of fluoride, but groundwater in volcanic or mountainous areas can have up to 50 mg/L. Fluoride comes from rocks like alkaline volcanic, hydrothermal, and sedimentary rocks. It dissolves into nearby water. In most drinking water, over 95% of fluoride is the F ion, and the next most common is the magnesium-fluoride complex (MgF). Fluoride levels are often controlled by the solubility of fluorite (CaF₂), which means high natural fluoride levels are linked to calcium-deficient, alkaline, or soft water.
Some bottled water may contain fluoride naturally or from public water supplies that have been fluoridated. The U.S. Food and Drug Administration (FDA) says bottled water labeled as de-ionized, purified, demineralized, or distilled should have no or only trace amounts of fluoride unless it is listed as an added ingredient.
The World Health Organization (WHO) sets guidelines for fluoride in drinking water. The lower limit helps prevent tooth decay, and the upper limit prevents harm like dental fluorosis. If fluoride levels are too low, fluoridation can increase them. If they are too high, treatment technology can reduce them. The WHO’s upper limit of 1.5 mg/L has been repeated since 1984. It may be lowered in some countries if people drink a lot of water or have other fluoride sources, like food or dental products. In 2011, the WHO said protection against tooth decay starts at 0.5 mg/L, and most fluoridation standards aim for 0.5–1.0 mg/L. The WHO does not set a specific target for fluoridation.
The European Food Safety Authority (EFSA) says fluoride is not an essential nutrient but has benefits for preventing tooth decay. It recommends an Adequate Intake (AI) of 0.05 mg/kg body weight per day for all ages. For a 60 kg adult, this equals 3 mg/day. EFSA’s upper legal limit for fluoride in water is 1.5 mg/L. In 2024, EFSA prepared a draft for daily fluoride intake limits for children.
In 2011, the U.S. Department of Health and Human Services (HHS) and the U.S. Environmental Protection Agency (EPA) lowered the recommended fluoride level to 0.7 mg/L. In 2015, the U.S. FDA, following the U.S. Public Health Service (PHS), advised bottled water manufacturers to limit fluoride to no more than 0.7 mg/L.
A 2007 Australian review suggested a range of 0.6–1.1 mg/L. Before 2011, U.S. recommendations were based on 1962 evaluations, which set fluoride levels between 0.7–1.2 mg/L depending on climate. Cooler climates had higher levels because people drink less water, and warmer climates had lower levels.
Between 1974 and 1989, the U.S. National Research Council listed fluoride as an essential nutrient. It removed this designation in 1989 because no studies showed it was essential for human growth, though it still called fluoride a "beneficial element" for oral health. Studies from the late 1980s and early 1990s found that children’s fluoride intake was about 0.05 mg/kg body weight per day in fluoridated areas and 0.03 mg/kg/day in non-fluoridated areas.
The U.S. Centers for Disease Control and Prevention (CDC) provides guidelines for water fluoridation, including requirements for staff, reporting, training, inspections, monitoring, and actions if too much fluoride is added. It also outlines technical details for each compound used.
The WHO recommends reaching adequate fluoride levels through fluoridation of low-fluoride water, milk, or salt, as well as using topical fluoride products like toothpaste, silver diamine fluoride varnish, and glass ionomer cement. It also advises avoiding excess fluoride by switching to an alternative water source or using defluoridation methods.
Defluoridation is needed when natural fluoride levels are too high. It can be done by filtering water through activated alumina, bone meal, bone char, or tricalcium phosphate; using alum to coagulate fluoride; or adding lime to cause fluoride to precipitate. Clay can also be used, but it must be free of toxic chemicals.
Pitcher or faucet-mounted water filters do not remove fluoride. More expensive reverse osmosis filters can remove 65–95% of fluoride, and distillation removes all fluoride.
Evidence
Water fluoridation helps reduce tooth decay. Studies show it can also cause dental fluorosis, which is usually mild and does not often affect appearance. There is no clear evidence of other harmful effects, though most research on this topic has not been very strong.
Reviews of studies show that water fluoridation reduces cavities in children. Evidence for its effectiveness in adults is less clear, with some studies showing benefits and others not. In the 1950s and 1960s, U.S. studies found that fluoridation reduced childhood cavities by 50% to 60%. Later studies in 1989 and 1990 showed smaller reductions (40% and 18%, respectively), likely because more children used fluoride from other sources, like toothpaste, and because of the "halo effect" of food and drinks made in fluoridated areas but eaten elsewhere.
A 2000 review in the UK found that fluoridation reduced cavities in children by 15% and decreased the number of decayed, missing, or filled baby teeth by an average of 2.25 teeth. The review noted the evidence was of moderate quality, as few studies tried to avoid bias or account for other factors. A 2007 review in Australia and a 2011 European review used similar methods and reached similar conclusions. A 2015 review by Cochrane estimated that fluoridation reduced cavities by 35% in baby teeth and 26% in permanent teeth for children without other fluoride sources. However, the evidence was weak. A 2020 study found that fluoridation improved dental health and labor outcomes but had no clear effect on cognitive ability.
Fluoridation may also help prevent cavities in adults. A 2007 study by CDC researchers found it prevented about 27% of adult cavities, similar to other fluoride sources. However, a 2011 European review found limited benefits for adults, and a 2015 Cochrane review found no strong evidence of effectiveness in adults. A 2016 review noted that stopping fluoridation programs often led to more cavities.
Many European countries have reduced cavities without fluoridation, due to widespread use of fluoride in toothpaste, mouth rinses, and other products. In Finland and Germany, cavities remained stable or decreased even after fluoridation stopped in some areas. In the U.S., fluoridation remains important because many children lack regular dental care and rely on water as their main fluoride source. The effectiveness of fluoridation depends on factors like access to free preventive care.
Dental fluorosis is the only clear adverse effect of fluoride at recommended levels. It can change the appearance of children’s teeth during development but is mostly mild and does not harm health. In 2015, the U.S. lowered recommended fluoride levels in water to 0.7 ppm to reduce fluorosis risk. A 2015 Cochrane review estimated that 12% of people had fluorosis that might concern appearance at 0.7 ppm, and 40% had fluorosis of any level. In the U.S., 20% of people have mild fluorosis, 2% have moderate, and less than 1% have severe.
The most critical time for fluoride exposure is between ages 1 and 4, with risk ending around age 8. Fluorosis can be avoided by monitoring all fluoride sources. Fluoridated water is estimated to cause about 40% of fluorosis risk, while toothpaste accounts for the remaining 60%. Compared to naturally fluoridated water (0.4 mg/L), adding fluoride to reach 1 mg/L may increase fluorosis in about 1 in 6 people and fluorosis of concern in about 1 in 22 people. In many countries, fluorosis rates are rising even without fluoridation, often due to fluoride from swallowed toothpaste. A 2009 review found weak evidence linking infant formula or water used to prepare formula to fluorosis, possibly due to publication bias. In the U.S., reduced tooth decay has been accompanied by increased fluorosis in both fluoridated and non-fluoridated areas, leading to global efforts to lower fluoride in formulas, toothpaste, and other products.
Fluoridation has little effect on bone fracture risk. It may slightly lower fracture risk compared to very high or no fluoride levels.
There is no clear link between fluoridation and cancer or cancer-related deaths, including bone cancer and osteosarcoma. Studies, including those by the NTP in 1990, found uncertain evidence of a link between fluoride and osteosarcoma in male rats, but no strong evidence of cancer risk in humans. Fluoridation is widely used globally to improve dental health and is considered a major health success. Fluoride levels in water are regulated, such as the U.S. Environmental Protection Agency limiting fluoride to no more than 4 milligrams per liter. Natural fluoride is already present in water, but many communities add more to reduce decay. Fluoride also helps form new bone, but research shows no increased risk of osteosarcoma from fluoridated water in humans. Studies comparing osteosarcoma rates in areas with different fluoride levels found no significant differences. Research on bone samples from osteosarcoma patients has not shown a clear connection to fluoride.
Mechanism
Fluoride mainly works by stopping the process that causes tooth decay. Tooth decay is a disease caused by bacteria in dental plaque, such as Streptococcus mutans and Lactobacillus. These bacteria produce acids when they break down carbohydrates, especially sugar. When the acid lowers the pH below 5.5, it dissolves hydroxyapatite, the main part of tooth enamel, in a process called demineralization. After sugar is no longer present, some of the lost minerals can return to the tooth through saliva, a process called remineralization. Cavities form when demineralization happens faster than remineralization, which often takes months or years.
Fluoridation methods, such as adding fluoride to water, increase low levels of fluoride ions in saliva and plaque fluid. This creates a protective effect on the tooth's surface. A person living in an area with fluoridated water may have fluoride levels in saliva reach about 0.04 mg/L several times daily. Fluoride does not stop cavities entirely but slows how quickly they develop. When fluoride is in plaque fluid with dissolved hydroxyapatite and the pH is above 4.5, a layer of fluorapatite-like material forms on the enamel. This layer is more resistant to acid than original hydroxyapatite and forms faster than regular remineralization. Most cavity prevention from fluoride happens through these surface effects, which occur during and after teeth erupt. Some fluoride from the body returns to saliva and unerupted teeth, but there is little data about how much of fluoride’s anticavity effect comes from these processes. Fluoride also affects bacteria in plaque, but its effect on bacterial growth does not seem to directly prevent cavities.
Fluoride’s effects depend on total daily intake from all sources. About 70–90% of ingested fluoride enters the bloodstream and spreads throughout the body. In infants, 80–90% of absorbed fluoride is stored, with the rest excreted mostly through urine. In adults, about 60% is stored. Nearly all stored fluoride is found in bones, teeth, and other calcium-rich areas. Too much fluoride can cause fluorosis. Drinking water is usually the largest source of fluoride. In areas without fluoridated water, swallowed toothpaste is often the main source. Other sources include dental products, air pollution from coal or fertilizers, trona used in Tanzania, and tea leaves, especially in parts of China. High fluoride levels are also found in foods like barley, cassava, corn, rice, taro, yams, and fish protein concentrate. The U.S. Institute of Medicine sets Dietary Reference Intakes for fluoride: 0.01 mg/day for infants under 6 months to 4 mg/day for men aged 19 and older. The Tolerable Upper Intake Level is 0.10 mg/kg/day for children under 8 and 10 mg/day for older individuals. An adult in a temperate climate typically consumes about 0.6 mg/day of fluoride without fluoridation and 2 mg/day with it. These values vary globally; for example, in Sichuan, China, average daily fluoride intake is 0.1 mg/day from drinking water, 8.9 mg/day from food, and 0.7 mg/day from air due to high-fluoride coal used for cooking and drying food indoors.
Alternatives
The ways to prevent tooth decay in communities are not all the same. A review by the Australian government says that adding fluoride to public water is the best way to give fluoride to many people at once. A review by the European Commission says there is no clear advantage to adding fluoride to water compared to applying fluoride directly to teeth. Other methods that help prevent tooth decay include fluoride toothpaste, mouthwash, gel, varnish, and adding fluoride to salt or milk. Dental sealants also help, with studies showing they can prevent between 33% and 86% of cavities, depending on the age of the sealant and the type of study.
Fluoride toothpaste is the most widely used and thoroughly tested fluoride method. Its use is linked to the decrease in tooth decay in industrialized countries, and it is the common factor in countries where tooth decay has dropped. In many low-income countries, fluoride toothpaste is the only practical option because water or salt fluoridation is not possible due to poor infrastructure. Toothpaste depends on individuals and families to use it, and it is less likely to be used by people with lower incomes because it can be too expensive. Fluoride toothpaste prevents about 25% of cavities in young permanent teeth. Its effectiveness increases when higher amounts of fluoride are used or when brushing is supervised. Fluoride mouthwash and gel are about as effective as toothpaste, while fluoride varnish prevents about 45% of cavities. Brushing with nonfluoride toothpaste has little effect on cavities.
Adding fluoride to salt works about the same as adding fluoride to water, if most salt used by people is fluoridated. Fluoridated salt reaches people through salt at home, in school meals, and in bread. For example, Jamaica started adding fluoride to all salt in 1987, which helped reduce cavities. Universal salt fluoridation is also used in Colombia and the Swiss Canton of Vaud. In Germany, fluoridated salt is available for purchase, but unfluoridated salt is also sold. Fluoride levels in salt range from 90 to 350 mg/kg, with studies suggesting 250 mg/kg is the best amount.
Adding fluoride to milk is done in some areas by the Borrow Foundation in parts of Bulgaria, Chile, Peru, Russia, Macedonia, Thailand, and the UK. Fluoride is added to milk, powdered milk, or yogurt. For example, in rural Chile, fluoridated powdered milk is used where adding fluoride to water is not possible. These programs focus on children and have not been tested for adults. A review found limited evidence to support this practice but said more studies are needed.
Other public health methods, like teaching people to change habits or improve diets, have not shown strong results. Fluoride is the only well-documented method that controls how quickly cavities form. Some suggest adding calcium to water might help reduce cavities further. Other methods include antibacterial treatments like chlorhexidine and sugar substitutes like xylitol. Xylitol-sweetened gum is sometimes recommended as a supplement to fluoride if it is not too costly. Two other ideas, replacing harmful bacteria with good ones (probiotics) and a vaccine for cavities, require little effort from patients but have not been proven safe or effective. Other experimental methods include fluoridated sugar, polyphenols, and casein phosphopeptide–amorphous calcium phosphate nanocomplexes.
A 2007 review in Australia said water fluoridation is the most effective and fair way to give fluoride to communities. A 2002 review in the U.S. found that sealants reduce cavities by about 60%, compared to 18–50% for fluoride. A 2007 review in Italy suggested water fluoridation might not be needed in industrialized countries where cavities are rare, and that toothpaste and other topical fluoride are better worldwide. A 2004 World Health Organization review said water fluoridation is very helpful in preventing cavities when it is accepted by the public and technically possible, especially for groups at higher risk.
Worldwide prevalence
As of November 2012, about 378 million people worldwide received water with fluoride added to it. Most of these people lived in the United States. Around 40 million people worldwide had water that naturally contained fluoride at levels considered safe and effective for dental health.
Early research linking fluoride to better dental health was conducted by scientists in the United States during the early 1900s. The United States was the first country to add fluoride to public water supplies on a large scale. Many other countries and regions outside the United States, such as Argentina, Australia, Brazil, Canada, Chile, Colombia, Hong Kong, Ireland, Israel, Korea, Malaysia, New Zealand, the Philippines, Serbia, Singapore, Spain, the United Kingdom, and Vietnam, also implemented water fluoridation to some degree. In 2004, about 13.7 million people in western Europe and 194 million in the United States received water with added fluoride. In 2010, about 66% of the United States population had access to fluoridated water.
Naturally fluoridated water was used by about 4% of the world’s population. This included countries such as Argentina, France, Gabon, Libya, Mexico, Senegal, Sri Lanka, Tanzania, the United States, and Zimbabwe. In some areas, like parts of Africa, China, and India, naturally occurring fluoride levels in water were higher than recommended.
Some countries have stopped adding fluoride to their water supplies, including Finland, Germany, Japan, the Netherlands, and Switzerland. Reasons for stopping included political disagreements about fluoridation, but some countries found other ways to provide fluoride, such as using fluoride in toothpaste or other products. Fluoride in different forms is widely used across Europe to prevent tooth decay. In some countries, like Switzerland and Germany, fluoridated salt makes up 65% to 70% of the salt sold. In France, fluoridated salt reached 60% of the market in 1993 but dropped to 14% by 2009. In Spain, fluoridated salt made up only 10% of the market in 2006. Legal rules for fluoridated salt exist in Greece, Austria, and the Netherlands. Some Central European countries, such as Hungary, Czechia, Slovakia, Croatia, Slovenia, and Romania, have explored fluoridated salt, but only the Czech Republic achieved about 35% usage. Slovakia had the tools to treat salt with fluoride by 2005, but other countries did not successfully use fluoridated salt.
Some countries have reviewed their use of fluoride due to concerns about overexposure and the effectiveness of fluoridation methods. Recent studies suggest that applying fluoride directly to teeth, such as through toothpaste or professional treatments, may be safer and more effective than adding fluoride to water. In 2014, Israel introduced a dental health program that included education, medical checkups, and fluoride products. Israel concluded that adding fluoride to water was no longer needed because it forces people who do not want fluoride to consume it. This approach is not widely accepted in most countries worldwide.
History
The history of adding fluoride to water can be divided into three main periods. The first period, from about 1801 to 1933, focused on studying a type of discolored tooth enamel called the Colorado brown stain. The second period, from about 1933 to 1945, examined how fluoride levels affect tooth decay and fluorosis, discovering that moderate fluoride helps prevent cavities. The third period, starting in 1945, involved adding fluoride to public water supplies to improve dental health.
In the first half of the 19th century, scientists found that fluoride is present in different amounts in teeth, bones, and drinking water. In the second half, they guessed that fluoride might protect teeth from decay, suggested adding fluoride to food, and noticed discolored enamel (now called severe dental fluorosis) without knowing why. In 1874, a German public health officer named Carl Wilhelm Eugen Erhardt recommended using potassium fluoride to help protect teeth. In 1892, a British doctor named James Crichton-Browne thought that switching to refined flour reduced fluoride in diets and made teeth more likely to decay. He proposed adding fluoride back to food in natural forms to strengthen teeth.
The idea of adding fluoride to water in the United States began with dentist Frederick McKay, who studied the Colorado brown stain for 30 years. He found that the stain was caused by fluoride, which also made teeth resistant to cavities. In 1925, a British dentist named Norman Ainsworth reported that the stain was linked to fewer cavities. In 1931, a chemist named H.V. Churchill discovered that fluoride was the common factor in water from areas with the stain.
In the 1930s and 1940s, H. Trendley Dean and others at the U.S. National Institutes of Health studied how fluoride levels in water affected tooth decay. They found that about 1 mg/L of fluoride reduced cavities without causing serious health or appearance issues. Studies also showed no major harm even at higher fluoride levels. To test if adding fluoride to water could prevent cavities, Dean and his team began fluoridating water in Grand Rapids, Michigan, in 1945. Results from 1950 showed fewer cavities. Similar studies in Canada, the Netherlands, New Zealand, and the United Kingdom also found significant reductions in tooth decay. Though these early studies were not as detailed as modern ones, they convinced health experts of fluoridation’s benefits.
By 1951, adding fluoride to water became an official policy of the U.S. Public Health Service. By 1960, fluoridation was used by about 50 million people in the United States. By 2006, 69.2% of people on public water systems in the U.S. received fluoridated water, covering 61.5% of the total population. About 3% of people on public water systems had naturally high fluoride levels. Other countries, like New Zealand, Brazil, and Ireland, also widely adopted fluoridation. In some places, fluoridation was later stopped, such as in Finland and Switzerland, where other dental programs reduced the need for it.
McKay’s research showed that fluorosis occurs before teeth come in. Dean and others believed fluoride protected teeth before they erupted, but this idea was incorrect. By 2000, scientists understood that fluoride in water and toothpaste works best when it stays in the mouth at low levels to prevent cavities.
Economics
Fluoridation costs about $1.39 per person each year on average, with costs ranging from $0.33 to $14.73. These costs are based on U.S. data from 2025 and adjusted for inflation. Larger water systems usually have lower costs per person. The cost also depends on factors such as the number of places where fluoride is added to water, the type of equipment used, the fluoride chemical and how it is transported and stored, and the expertise of water plant workers. In wealthier countries, adding fluoride to salt is very cheap. In poorer countries, it might be too expensive to buy the fluoride additive. Fluoride toothpaste costs about $12–$23 per person each year. If people already brush their teeth for other reasons, there is no extra cost for using toothpaste. Dental cleanings and applying fluoride varnish or gel cost about $128 per person each year. In the worst case, fluoridation costs about $21–$33 to save one tooth-decay surface. This is cheaper than fixing the surface ($126) or the total cost over time of the decayed surface ($213). It is not known how much industrial countries spend on treating dental fluorosis, which is mostly caused by swallowing toothpaste.
A 1989 meeting on the cost-effectiveness of preventing cavities concluded that water fluoridation is one of the few public health measures that save money. However, there is not much high-quality research on this topic, and reliable data are limited. Dental sealants are cost-effective only when applied to children at high risk for cavities. A 2002 U.S. review found that sealing first permanent molars saves money when decay occurs faster than 0.47 surfaces per person each year. Water fluoridation saves money when total decay is more than 0.06 surfaces per person each year. In the U.S., water fluoridation is more cost-effective than other methods to reduce tooth decay in children. A 2008 review concluded that water fluoridation is the best tool for preventing cavities in many countries, especially among socially disadvantaged groups. A 2016 review of studies from 1995 to 2013 found that water fluoridation in the U.S. was cost-effective, and it was even more so in larger communities.
U.S. data from 1974 to 1992 show that when fluoridation is introduced into a community, the number of dental workers and dental offices decreases. This suggests that some dentists may move to areas without fluoridation or retrain as specialists.
Controversy
The water fluoridation controversy comes from different concerns about politics, morals, ethics, money, and safety related to adding fluoride to public water supplies. International and national groups, as well as dental organizations worldwide, say that fluoridation is safe and works well for people with low income in both developing and developed countries. Experts have different opinions about the best way to use fluoride to prevent tooth decay in communities; some believe adding fluoride to water is most effective, while others think it has no special advantage and prefer applying fluoride directly to teeth.
People who disagree say fluoridation may not help much in preventing tooth decay, could cause serious health problems, is not worth the cost, is no longer considered the best method, and creates a conflict between what is best for everyone and individual choices.