The use of fluoride has been endorsed as a safe and effective method of preventing tooth decay by most major health and safety-related organizations. When fluoride enters the mouth it is deposited into the teeth and bones, strengthening teeth during a process called remineralization.

Fluoride is a mineral that appears naturally in soil, water, air and certain foods. It is often added to community drinking water when levels are deemed insufficient to help protect against tooth decay. Sometimes fluoride supplements (in the form of tablets, drops or lozenges) are used to compensate for drinking water without adequate fluoridation.

Fluoride is also directly applied to the teeth as part of routine oral care. Brushing teeth with fluoride toothpaste is an important component of good daily dental hygiene. Fluoride may also be topically applied as fluoride gels, mouth rinses, and during professionally applied fluoride treatments. Anyone at high risk of tooth decay may benefit from fluoride treatments that use higher concentration levels of fluoride than those available in over-the-counter products.

All age groups can benefit from fluoride. In children, fluoride fortifies and strengthens teeth while they are still forming. Children who receive adequate levels of fluoride during this time develop permanent teeth that are more resistant to decay the moment they appear in the mouth. Adults with root exposure or dry mouth are particularly susceptible to tooth decay, and can benefit from tooth-strengthening applications of fluoride.

Risks are associated with exposure to high levels of fluoride over prolonged periods of time. Dental fluorosis affects teeth that are still forming and have not yet erupted into the mouth, and most often occurs in children who take fluoride supplements in addition to consuming adequate levels of fluoridated water.

Large concentrations of fluoride consumed at one time may be toxic or even fatal, especially to small children. Bone weakening and skeletal fluorosis (which cause joint stiffness and pain) have been associated with exposure to high levels of fluoride for long periods of time, although further study is needed in these areas.

Parents or caregivers can help prevent fluoride overdose by supervising the use of fluoride products in children during dental hygiene. Parents should also keep all fluoride products (including toothpaste and mouth rinses) out of reach of children and avoid stockpiling fluoride supplements to help prevent cases of accidental overdose.

Maintaining adequate fluoride levels is important to prevent tooth decay and reduce the risks of overexposure, such as dental fluorosis. This includes identifying and monitoring fluoride levels in drinking water sources, whether community, well or bottled water. In some cases of naturally high levels of fluoridated water, it may involve filtering fluoride from drinking water with certain types of home filtering systems.

Fluoride is a component of the mineral fluorine that is naturally present in soil, water, air and certain foods (e.g., meat, fish, eggs, tea leaves). It is commonly added to community drinking water, and may be added to various foods and beverages during processing. Most people absorb fluoride through drinking water and the use of dental hygiene products that contain fluoride.

Fluoride is used to protect against tooth decay, cavities and the complications that can result. Tooth decay begins with demineralization. This occurs when bacteria naturally present in the mouth combine with sugar (remaining in the mouth from foods or beverages consumed) to produce acid that erodes tooth enamel. When demineralization is allowed to continue by not cleaning the teeth, it can lead to the formation of holes in the enamel. All cavities occur in this way.

Minerals such as fluoride, calcium and phosphate help to correct demineralization by strengthening weakened areas of tooth enamel. Fluoride accumulates in teeth and bones, adhering to areas where demineralization has occurred and making the enamel harder than it was before. The rebuilding of tooth enamel is called remineralization. It strengthens teeth and helps to prevent cavities, but cannot restore an area once a cavity has formed. Fluoride is also absorbed into plaque, and inhibits its growth by disrupting the acid-producing activity of bacteria in the mouth.

When fluoride is ingested, it enters the bloodstream and is absorbed into the teeth and bones. Fluoride may also be directly applied to teeth, where it is absorbed into tooth enamel. Fluoride levels in the mouth remain high for several hours after a topical application.

Daily use of fluoride is considered an important component of dental health care for all age groups. The Centers for Disease Control and Prevention (CDC) recommends that children and adults use small amounts of fluoride on a regular basis to help reduce tooth decay.

Fluoride is especially helpful for children whose permanent teeth are still developing. Teeth can be fortified with fluoride while they are still forming and before they have erupted. This way, a child’s permanent teeth are more resistant to decay the moment they appear in the mouth.

Fluoride is important for adults, too. According to the CDC, fluoride reduces tooth decay in adults by 20 to 40 percent. Older adults are particularly susceptible to root exposure (which can occur due to receding gums or gum disease, both of which are more likely to occur as a person ages) and dry mouth. These conditions can increase the risk of tooth decay, and the newly exposed surfaces require fluoride for strengthening and remineralization.

The use of fluoride is important because tooth decay remains a significant problem in the United States. More than two-thirds of American children and adolescents experience tooth decay, according to the CDC. The risk of decay increases as people age. Ninety-one percent of American adults (and 93 percent of those over 60 years old) have experienced tooth decay, according to the CDC.

People with a high risk of tooth decay may find the use of fluoride especially beneficial. This includes people with the following risk factors for tooth decay:

• History of cavities. People with a history of tooth decay may be more susceptible to tooth decay in the future.
  
  
• Infrequent dental visits. Regular dental examinations can identify problems while they are easy to fix (e.g., small cavities, buildup of plaque). Failure to visit the dentist regularly can lead to larger problems as the result of tooth decay.
  
  
• Poor dental hygiene. Failing to brush and floss the teeth daily can lead to the buildup of plaque and tartar, resulting in tooth decay.
  
  
• Diet high in sugar/carbohydrates. High levels of carbohydrates in the diet may leave sugar in the mouth, which acts as fuel for the bacteria that cause demineralization.
  
  
• Frequent snacking. People who frequently snack expose their teeth to a continual process of demineralization that can lead to decay.
  
  
• Braces. Braces can trap bacteria and food particles on the teeth, which may be difficult to remove with brushing and flossing.
  
  
• Crowns, bridges. Teeth with dental restorations such as crowns or bridges are still susceptible to decay where the restoration meets the tooth.
  
  
• Dry mouth. A lack of saliva in the mouth may be caused by a number of medical conditions (e.g., diabetes, Sjogren’s syndrome) and many different medications (e.g., drugs for allergies, high blood pressure, anxiety, depression, and radiation therapy).  

Water fluoridation involves adjusting the amount of fluoride naturally present in water. Fluoride is added to many communities’ drinking water when it falls below a certain concentration level. Community water that is fluoridated in this manner is monitored daily to ensure that proper levels of fluoridation are maintained.

The optimal range for fluoride levels in drinking water is between 0.7 to 1.2 parts per million (ppm) or milligrams per liter, according to the U.S. Public Health Service. Lower levels of this range are appropriate in warm-weather areas of the United States, and higher levels of this range apply to colder climates. This allows for the propensity of people in warm areas to drink more water than those in colder environments.

Fluoride was first added to community drinking water in the United States in 1945. Studies of its effects over a 15-year period found that fluoridated water reduced tooth decay in children by 60 percent.

Today, the people who use community water systems receive adequate levels of fluoride in the water. Fluoridated drinking water and beverages containing fluoride are the largest contributors to a person’s total consumption of fluoride. Children and adults alike benefit from the decay-preventing properties of fluoridated water.

Most people support water fluoridation. However, people who oppose it have questioned its safety and argued that it is a decision imposed upon them by others. The debate over whether or not to add fluoride to the water in some communities continues.

Water fluoridation has been determined to be a safe and effective method of preventing tooth decay by most major health and safety-related organizations. This includes the American Dental Association, the U.S. Centers for Disease Control and Prevention (CDC) and the American Academy of Pediatric Dentistry. In October 2006, the U.S. Food and Drug Administration (FDA) approved the health claim "Drinking fluoridated water may reduce the risk of tooth decay" for use on bottled waters that contain between 0.6 and 1.0 milligrams per liter (mg/L) of total fluoride. However, this claim is not approved for bottle water products marketed specifically for use by infants.

Periodic assessments of drinking water regulations occur to ensure the safety of communities participating in water fluoridation programs.

For example, the Environmental Protection Agency (EPA) has set a maximum allowable level of fluoride in drinking water. Water is considered safe for drinking if fluoride levels do not exceed 4 ppm (although the optimal level in drinking water remains between 0.7 and 1.2 ppm). In 1993, the National Research Council (NRC) reported that the 4 ppm maximum was appropriate until additional studies could be performed.

In March 2006, the NRC recommended lowering the 4 ppm maximum. Its report included a finding that water with naturally occurring levels of fluoride above 2 ppm may cause dental fluorosis in children. This exposure may occur in communities that do not regulate fluoride levels in the water, or among those who rely on well water with naturally occurring high levels of fluoride. The NRC finding remains consistent with the established optimal level of fluoride (0.7 to 1.2 ppm) in public water systems.

Water fluoridation is considered a cost-effective method of delivering fluoride to all members of a community. The CDC recommends drinking fluoridated water in addition to using fluoride products on a regular basis (e.g., brushing teeth twice a day with a fluoride toothpaste) as part of a good dental hygiene program.

Fluoride treatments are professionally applied in a dental office. They are recommended for people with a moderate to high risk of tooth decay (e.g., people with a history of cavities, infrequent dental visits, poor dental hygiene, diet high in sugar). This may include children and adults.  

Professionally applied fluoride treatments provide extra protection against tooth decay. These treatments are safe and effective. It is typically recommended that they be performed twice a year, even if high risk patients already drink fluoridated water and use dental care products that contain fluoride. 

The fluoride used for these treatments has a higher concentration level and different chemical makeup than the flouride found in over-the-counter products. The types of fluoride used for professional fluoride treatments include:

• Acidulated phosphate fluoride (APF). This is the most commonly used type of fluoride. It is available in foam or gel form, at a fluoride concentration level of 1.23 percent. APF is slightly astringent and may irritate gum tissue in patients with dry mouth. It does not discolor teeth or restoratives (e.g., fillings, crowns), although it may cause scratches in porcelain or composite resins.
  
  
• Neutral sodium fluoride. This was the first fluoride used in topical applications. It is commonly available as a 2 percent concentrate foam or gel or a 5 percent concentrate varnish. It is nonirritating and does not discolor teeth. In children, it is typically used once a week for four weeks and recommended at ages 3, 7, 10 and 13 years. In adults, the gel or foam may be applied every six months and the varnish may be applied every four months. Neutral sodium fluoride may be used as an alternative to APF when porcelain or composite restorations are present, or in patients with dry mouth.
  
  
• Stannous fluoride. Available as a powder that can be mixed with water to make an 8 percent concentrate gel, just before application. It has a disagreeable taste, may irritate the gums, and may discolor the teeth and gums (due to tin in the solution, not fluoride). This type contains a high concentration of fluoride, and is recommended for people at high risk of tooth decay.

Before a fluoride treatment, a patient’s teeth will be cleaned. Teeth are then dried to avoid diluting the fluoride when it comes into contact with them. The fluoride is then applied to the teeth.

When fluoride is a gel or foam, a tray that looks like a mouth guard is filled with the fluoride then kept in the mouth (so the solution covers the teeth) for one to four minutes. Patients may be instructed to spit and the mouth area may be wiped with gauze. Patients are often advised to refrain from eating, drinking, rinsing or smoking for 30 minutes after a treatment. This maximizes fluoride’s contact with teeth and effectiveness of the treatment.

If fluoride is a varnish, it is painted onto the teeth (including any exposed tooth root) and quickly dries. Patients may be advised to spit and to avoid eating, drinking, smoking or rinsing the mouth for at least 30 minutes after application.

Fluoride varnish is not currently approved by the Food and Drug Administration (FDA) for use in cavity prevention. It has been approved for treatment of tooth sensitivity, although it is also commonly used to help prevent tooth decay. Fluoride varnish has been used in this capacity in Canada and Europe since the 1970s and is documented to be effective for this purpose.

The fluoride used in professionally applied treatments is frequently flavored to make the experience more palatable for patients, but it should never be swallowed.

In addition to fluoridated water and fluoride treatments received in dental offices, patients may receive fluoride from other sources. These are not typically major sources of fluoride for most people, but they do contribute to total daily fluoride consumption levels. Use of fluoridated water in addition to fluoride from other sources (such as topical fluoride products) is recommended by the Centers for Disease Control and Prevention (CDC) as part of a good dental hygiene program for all age groups. 

Additional forms of fluoride are either topically applied or ingested. It is important not to eat or drink for at least 30 minutes after topical application of fluoride to maximize its contact with teeth. When purchasing over-the-counter fluoride products, it is important to look for the American Dental Association Seal of Acceptance.   

Additional sources of fluoride include:

• Toothpaste with fluoride. Available over-the-counter and recommended for use by adults and children over 2 years old. Typically advised for use twice a day while brushing teeth.
  
  
• Mouth rinse with fluoride. Available over-the-counter and by prescription in higher strengths. Recommended for anyone over the age of 6 years (due to the risk of swallowing). Teeth should be cleaned by brushing and flossing prior to use. These mouth rinses may be especially helpful for patients with braces or other dental appliances that can trap bacteria, making removal by brushing alone difficult. Mouth rinses with fluoride may be used daily or weekly.
  
  
• Fluoride gels. Available by prescription and recommended for people at high risk of tooth decay (e.g., people with a history of cavities, inadequate dental hygiene or dental visits, poor diet). Fluoride gels are usually applied with a toothbrush.
  
  
• Fluoride supplements. Available by prescription in tablet, liquid or lozenge form. Supplements are recommended for children between the ages of 6 months and 16 years who do not receive adequate levels of fluoride in the water they drink. These are typically based on a child’s age and the amount of fluoride ingested through other sources. Supplements should be taken every day. Liquid forms may be dropped directly in the mouth, or mixed with food or beverages. Tablets and lozenges are designed to be chewed or sucked for a minute or two before being swallowed.

Fluoride is also found in many different types of food and beverages. Anything cooked in or processed with fluoridated water will contain some fluoride. Levels of fluoride in these products may occur at levels similar to that found in fluoridated water (0.7 to 1.2 parts per million). Meat, fish (including bones), seafood, eggs, green/leafy vegetables and fruit may contain fluoride. Beverages such as fruit juice, tea (including iced tea) and bottled water may also contain fluoride. In addition, cooking with Teflon-coated or aluminum pans may add fluoride to foods.

Some bottled water may have fluoride added to it. Companies that add fluoride to the water are required to list the amount on the label. However, companies are not required to put this information on their label if it comes from natural sources and is not added to the water. Patients, caregivers or parents concerned about fluoride levels should check with the manufacturer about possible fluoride levels in bottled water. The Food and Drug Administration (FDA) is responsible for regulating fluoride in beverages (e.g., bottled water). Some fluoridated bottle water products may be labeled with a health claim that fluoride may reduce the risk of tooth decay.

Fluoride is safe and effective when used properly. However, some risks have been associated with exposure to high levels of fluoride for prolonged periods of time. These include:

• Dental fluorosis. Most commonly involves minor discoloration of tooth enamel, such as the appearance of white or opaque lines, streaks or spots. In severe cases, the discoloration may appear as brown, black or gray spots, and the enamel may become pitted or misshapen. Fluorosis is cosmetic and only affects the tooth’s surface. It is a permanent condition, and discoloration generally darkens as a person ages. Fluorosis may be treated by teeth whitening, bonding, crowns or veneers.
  
  Fluorosis occurs in children whose teeth are still developing. Once teeth have erupted in the mouth, they are no longer susceptible to fluorosis. Most cases of fluorosis occur when children take fluoride supplements (or swallow large amounts of fluoride toothpaste or mouth rinse) in addition to receiving adequate levels of fluoride in their drinking water. Some children develop fluorosis due to naturally high levels of fluoride in their drinking water. Fluoride treatments are not likely to contribute to fluorosis due to the relative infrequency of these professional applications.
  
  
• Bone weakening. A lifetime exposure to high levels of fluoride has been found to increase bone density, but not necessarily strength. Animal studies and several studies on the effect of fluoride in humans have shown an association with increased brittleness of bone. However, more research is needed to conclusively identify fluoride as the cause of this increased risk of bone fracture.
  
  
• Skeletal fluorosis. A disorder of the bones and joints associated with prolonged exposure to high levels of fluoride. It can cause joint stiffness and pain. Scientific evidence is inconclusive about the relationship between fluoride and skeletal fluorosis, and more research is needed. This is an extremely rare condition in the United States. 

Chronic exposure to high levels of fluoride may worsen certain existing medical conditions, such as joint pain, kidney problems and stomach ulcers. At this time, there is no conclusive evidence linking high levels of fluoride with cancer (e.g., bone cancer). Research continues in this area.

Allergic reactions to fluoride may occur in a small number of cases. Very small amounts of fluoride may pass into breastmilk, but no problems have been associated in children whose mothers consumed recommended levels of fluoride while pregnant or breastfeeding. 

Fluoride overdose may occur when large concentrations of fluoride are consumed at once. For example, small children who swallow large amounts of fluoride toothpaste (e.g., an entire tube by a small child) or fluoride mouth rinse, or take an overdose of fluoride supplements, may consume toxic levels of fluoride.

Toxic effects of fluoride will depend on the person’s age, weight and amount of fluoride consumed. For example, 320 milligrams (mg) of fluoride will have a toxic effect on a 2-year-old who weighs 22 pounds (10 kilograms [kg]). About 655 mg of fluoride may be toxic to an 8-year-old who weighs 45 pounds (20 kg). If medical attention is not received immediately, death may occur.  

Symptoms of fluoride overdose include:

• Nausea
• Vomiting (may include blood)
• Diarrhea (stool may be black, tarry)
• Abdominal pain
• Excessive salivation
• Watery eyes
• Weakness
• Shallow breathing
• Faintness
• Drowsiness
• Tremors, convulsions

Medical attention should be sought immediately for the above symptoms. If fluoride overdose is suspected, drinking milk may slow the absorption of fluoride in the body.

Any concerns about fluoride use should be brought to the attention of a dentist or physician. In addition, a local poison control center or the national poison control hotline (1-800-222-1222) can provide information about fluoride use and possible overdose.

The United States Department of Agriculture determines recommended dietary allowances (RDA) for various vitamins and minerals. Although fluoride has been endorsed as a safe and effective method of preventing tooth decay, no RDA for fluoride has been established. The following are general guidelines for daily fluoride consumption (in milligrams [mg]) according to the National Institutes of Health (NIH):

Total daily consumption of fluoride includes fluoride from water and other beverages, food, fluoride supplements and the use of dental care products that contain fluoride. Many people typically consume 1 mg of fluoride per day from their drinking water, and less than 1 mg of fluoride per day from food sources. These levels may differ, depending on the level of fluoride in drinking water and to what extent nonfluoridated bottled water is consumed.

The ideal range of fluoride in drinking water is between 0.7 and 1.2 parts per million (ppm). To determine the level of fluoride in drinking water, a person may do the following:

• Contact the local water utility. They are required by the Environmental Protection Agency to publish fluoride levels in annual water quality reports.
  
  
• Test private well water. Tests should be performed once a year to check fluoride levels. The well owner can arrange for a testing laboratory to send the collection containers and analyze the samples.
  
  
• Contact the bottled water manufacturer. When bottled water is the primary source of drinking water, the manufacturer should be contacted for information about potential fluoride levels.

If drinking water has inadequate levels of fluoride, fluoride supplements may be used for children between the ages of 6 months and 16 years. This helps to strengthen permanent teeth while they are still forming. Before a child receives fluoride supplements, parents or caregivers should inform the dentist about all sources from which the child receives fluoride, including the level of fluoride in the drinking water. The concentration of fluoride in supplements ranges from 0.25 mg to 1 mg per day.

In areas where drinking water contains high levels of fluoride, fluoride may be filtered from the water at home. Some home filtering systems (e.g., reverse osmosis, distillation) remove significant amounts of fluoride from drinking water. However, filters that attach to a water faucet or are present in pitchers (e.g., charcoal or carbon filters, water softeners) do not generally remove fluoride. People using any of these systems can check with the manufacturer for information on the filter’s ability to remove fluoride. 

Dental products that contain fluoride (e.g., fluoride toothpaste and mouth rinse) play an important role in the prevention of tooth decay. Although they have higher concentration levels of fluoride than drinking water, they are not typically a major source of fluoride because they are consumed in very small amounts. Examples of fluoride levels in these products include:

Because of the higher concentration of fluoride in these products, a pea-sized dab of fluoride toothpaste provides the same amount of fluoride (0.25 mg) as an eight-ounce glass of 1 ppm fluoridated drinking water. In practical use, many people receive more fluoride from the water they drink than they do from dental care products. Water is consumed in greater quantities and much more often during the day than these products.

Any concerns about fluoride levels should be brought to the attention of a dentist or physician.

Parents or caregivers can help to prevent the consumption of high levels of fluoride or fluoride overdose in their children. Tips to help parents manage their child’s fluoride consumption include:

• Monitor fluoride levels in drinking water. If fluoride levels in drinking water are above 2 ppm, parents should use an alternate, nonfluoridated source of water for children under 8 years old or whose permanent teeth are still forming. This helps to prevent the risk of dental fluorosis. The local water district can provide information on fluoride levels in water.
  
  
• Supervise children using fluoride products. Parents should carefully supervise young children during dental hygiene. Children may swallow fluoride toothpaste or mouth rinse, accidentally ingesting more fluoride than intended. Children under 6 years should not use mouth rinses due to a tendency to swallow rather than spit them out. Fluoride toothpastes may be used in children over the age of 2 years. During brushing, parents can ensure that their children:
  
  
• • Avoid flavored toothpastes, which may encourage swallowing
    
  • Use only the amount of toothpaste necessary (pea-size)
    
    
• Keep all fluoride products out of reach of children. Preventing child access to fluoride products may help prevent accidental fluoride overdose. This includes fluoride toothpastes, mouth rinses and fluoride supplements.
  
  
• Do not stock up on fluoride supplements. Dentists usually do not prescribe more than a certain level of fluoride supplements at a time to prevent the risk of overdose should a child take all supplements at once. To avoid the risk of accidental overdose, parents should not stockpile supplements.
  
  
• Use supplements only in certain circumstances. Supplements should only be taken if they are prescribed by a dentist or physician  and children do not receive adequate levels of fluoride in their drinking water.
  
  
• Separate supplement and calcium consumption. Calcium products (e.g., milk) may interfere with the body’s ability to absorb fluoride. When children are taking fluoride supplements, foods or beverages containing calcium should be consumed hours before or after the supplements to avoid this interference.   

Although the issue has not been sufficiently studied, taking fluoride supplements during pregnancy does not appear to provide any significant prenatal advantage to children compared to fluoride intake after birth. 

Preparing questions in advance can help patients to have more meaningful discussions regarding their conditions. Patients or parents may wish to ask their dentist the following fluoride-related questions:

1. Am I receiving an appropriate amount of fluoride?
   
   
2. How can I tell how much fluoride I consume daily?
   
   
3. Should my child receive fluoride supplements?
   
   
4. If my child receives supplements, will certain foods or beverages (e.g., products with calcium) interfere with the absorption of fluoride in the body?
   
   
5. At what age should my child stop taking fluoride supplements? Why?
   
   
6. At what age should my child begin using dental care products that contain fluoride, such as fluoride toothpaste or mouth rinse?
   
   
7. What should I do if my child swallows fluoride toothpaste or mouth rinse?
   
   
8. Should my child or I receive fluoride treatments? If so, how often?
   
   
9. What are the chances my child will develop dental fluorosis? How can I prevent this?
   
   
10. We recently moved to a new city serviced by a different water utility. Will the level of fluoride in my child’s supplements need to be adjusted?