What is fluoride?

Fluoride is a mineral that occurs naturally in many foods and water.

Every day, a tooth’s enamel layers add and lose minerals. Minerals are lost (demineralization) when acids – formed from plaque bacteria and sugars in the mouth – attack the enamel. Minerals such as fluoride, calcium and phosphate are returned (remineralization) into the enamel layer from the foods and water consumed. Tooth decay simply comes from too much demineralization without enough remineralization to repair the enamel layer.

Fluoride helps prevent decay by making the tooth more resistant to acid attacks. It also reverses early decay. Fluoride is 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 teeth of both children and adults.

How is fluoride available?

Fluoride is found in foods and water, and of course fluoridated toothpastes and mouth rinses. Mouth rinses containing fluoride in lower strengths are available over-the-counter. Stronger concentrations in liquid or table form need a doctor’s prescription.

A dentist 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 through a mouth guard.

At what age is fluoride intake most important?

Infants and children between the ages of 6 months and 16 years certainly need to get an appropriate amount of fluoride to prevent tooth decay. Primary and permanent teeth come in during these years.

However, the American Dental Association (ADA) recommends watching the intake of too much fluoride in infants and young children. The ADA specifically recommends avoiding reconstituted liquid formula, such as liquid concentrate or powdered baby formula that needs to be mixed with water containing fluoride.

Instead, it recommends 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 that can appear on tooth enamel during children’s’ 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?

Yes. 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.

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

  • Dry mouth conditions – can be 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 – exposes more of your tooth and tooth roots to bacteria and increases 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.

Are there any risks associated with fluoride use?

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).

Parents should carefully supervise their children’s use of fluoride-containing products and to keep fluoride products out of reach of children, especially under the age of 6. A few useful reminders include:

  • 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.

Keep in mind, however, that it’s very difficult to reach hazardous levels given the low levels of fluoride in home-based fluoride-containing products. If you do have concerns 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.

Does drinking bottled water put me at risk for tooth decay?

There are no scientific studies to suggest that people who drink bottled water are at increased risk of tooth decay. However, you could be missing out on the decay-preventing effects of optimally fluoridated water available from your community water source. 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 bottled 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 once a year 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.

You can 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.

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