What is fluoride?

Fluoride is a mineral that occurs naturally in many foods and water. While not everyone has access to naturally fluoridated water and food, fluoride can also be added to your community water supply following Centers for Disease Control and Health and Human Services guidelines.

How does fluoride prevent tooth decay?

Every day, minerals are added to and lost from a tooth’s enamel layer through two processes known as demineralization and remineralization. Minerals are lost (demineralization) from a tooth’s enamel layer when acids – formed from plaque bacteria and sugars in the mouth – attack the enamel. Minerals such as fluoride, calcium and phosphate are redeposited (remineralization) to the enamel layer from the foods and water consumed. Too much demineralization without enough remineralization to repair the enamel layer leads to tooth decay.

Fluoride helps prevent decay by making the tooth more resistant to acid attacks. It also reverses early decay. Fluoride becomes incorporated into the developing permanent teeth, making it difficult for acids to demineralize the teeth. Fluoride also helps speed remineralization as well as disrupts acid production in already erupted teeth of both children and adults.

In what forms is fluoride available?

Fluoride is found in foods and in water. It can also be directly applied to the teeth through fluoridated toothpastes and mouth rinses. Mouth rinses containing fluoride in lower strengths are available over-the-counter; stronger concentrations require a prescription.

A dentist in his or her office can also apply fluoride to the teeth as a gel, foam, or varnish. These treatments contain a much higher level of fluoride than the amount found in toothpastes and mouth rinses. Varnishes are painted on the teeth; foams are put into a mouth guard, which is applied to the teeth for 1 to 4 minutes; gels can be painted on or applied via a mouth guard.

Fluoride supplements are available as liquids and tablets and are also a product that must be prescribed by your dentist, pediatrician or family doctor.

Is there an age at which fluoride intake is most critical?

It is certainly important for infants and children between the ages of 6 months and 16 years to be exposed to an appropriate amount of fluoride to prevent tooth decay. These are the timeframes during which the primary and permanent teeth come in. However, the American Dental Association (ADA) now recommends being more watchful of the possible excessive intake of fluoride in infants and young children. The ADA’s guidance for infants specifically recommends avoiding reconstituted liquid formula – ie, liquid concentrate or powdered baby formula that needs to be mixed with water containing fluoride. Instead, they recommend breast milk, ready-to-feed formula, or prepared formula that is mixed with fluoride-free water. The ADA’s recommendations are to guard against enamel fluorosis – faint white streaks (ie, a cosmetic defect) that can appear on tooth enamel during their development, even before the teeth erupt through the gums.

For young children, the ADA also recommends:

  • Using a pea-sized amount of fluoride toothpaste at each brushing and spitting out rather than swallowing the toothpaste; children under age 2 should not use a fluoride-containing toothpaste.
  • Not allowing children under age 6 to use fluoride mouth rinses unless recommended by a dentist or other health professional.
  • Not giving fluoride-containing dietary supplements to children under 6 months of age.

Do adults benefit from fluoride intake?

Absolutely. New research indicates that topical fluorides – from toothpastes, mouth rinses, and fluoride treatments – are as important in fighting tooth decay as in strengthening developing teeth.

Situations that may put adults at higher risk of tooth decay and therefore would benefit from additional fluoride include:

  • Dry mouth conditions – caused by diseases such as Sjögren’s syndrome, certain medications (such as allergy medications, antihistamines, anti-anxiety drugs, and antihypertensives) and head and neck radiation treatment. Lack of saliva makes an individual more prone to tooth decay by not allowing food particles to be washed away or allowing acids to be neutralized.
  • Gum disease – can expose more of your tooth and tooth roots to bacteria and increase the chance of tooth decay.
  • History of frequent cavities – consisting of one cavity every year or every other year could indicate that you are the type of person who could benefit from additional fluoride.
  • Presence of crowns and/or bridges or braces – can put teeth at risk for decay at the point where the crown meets the underlying tooth structure or around the brackets of orthodontic appliances.

Where can I find out how much fluoride is in my tap water?

Contact your local or state health department or contact your local water supplier. Information for contacting your local water supplier should be on your water bill or see the "local government" section of your phone book.

Seventy-four (74) percent of the US population served by public water supplies has access to adequate levels of fluoride in their water, and 44 of the 50 largest US cities have water fluoridation systems.

Are there any risks associated with fluoride use?

Overall health effects. Fluoride is safe and effective when used as directed but can be hazardous at high doses (the "toxic" dosage level varies based on an individual’s weight). For this reason, it’s important for parents to carefully supervise their children’s use of fluoride-containing products and to keep fluoride products out of reach of children – and especially children under the age of 6. A few useful reminders include:

  • Store fluoride supplements away from young children.
  • Avoid flavored toothpastes because these tend to encourage toothpaste to be swallowed.
  • Use only a pea-sized amount of fluoridated toothpaste on a child’s toothbrush.
  • Be cautious about using fluoridated toothpaste in children under age 6. Children under 6 years of age are more likely to swallow toothpaste instead of spitting it out.

It should be kept in mind, however, that it’s very difficult to reach hazardous levels given the low levels of fluoride in home-based fluoride-containing products. Nonetheless, if you do have concerns or questions about the amount of fluoride you or your child may be receiving, talk to your dentist, pediatrician or family doctor.

Tooth discoloration. Excess fluoride can cause defects in the tooth’s enamel that range from barely noticeable white specks or streaks to cosmetically objectionable brown discoloration. These defects are known as fluorosis and occur when the teeth are forming -- usually in children under 6 years. This is why the ADA issued its guidance on fluoride intake in infants (explained earlier in this document). Fluorosis is more typically associated with naturally occurring fluoride, such as that found in well water. If you use well water and are uncertain about the mineral (especially fluoride) content, a water sample should be tested. Although tooth staining from fluorosis cannot be removed with normal hygiene, your dentist may be able to lighten or remove these stains with professional-strength abrasives or bleaches.

I drink bottled water, am I missing out on the benefits of fluoride?

Even though there are no scientific studies to suggest that people who drink bottled water are at increased risk of tooth decay, the ADA says that such people could be missing out on the decay-preventing effects of optimally fluoridated water available from their community water source. The ADA adds that most bottled waters do not contain optimal levels of fluoride, which is 0.7 parts per million (this is the amount that is in public water supplies, in the communities that have fluoridated water). To find out if your brand of bottled water contains any fluoride, check the label on the bottle or contact the bottle water manufacturer.

Does a home water treatment system affect the level of fluoride in my family’s drinking water?

The amount of fluoride your family receives depends on the type of home water treatment system used. Steam distillation systems remove 100 percent of fluoride content. Reverse osmosis systems remove between 65 percent and 95 percent of the fluoride. On the other hand, water softeners and charcoal/carbon filters generally do not remove fluoride. One exception: some activated carbon filters contain activated alumina that may remove over 80 percent of the fluoride.

If you use a home water treatment system, have your water tested at least annually to establish the fluoride level your family is receiving in the treated water. Testing is available through local and state public health departments as well as private laboratories. Also, check with the manufacturer of the product you purchased or read the information that came with the water treatment system to determine the product’s effects on fluoride in your home water.