How does fluoride protect against cavities?

An exposure to fluoride (like that contained in toothpaste and city tap water) is probably the most effective cavity-prevention treatment available today.

Cavity Prevention 

Dental researchers have shown that introducing fluoride into a previously unfluoridated city's drinking water supply can reduce its inhabitants' rate of tooth decay between 40 and 70 percent. Those are giant numbers.

Is your tap water fluoridated?

Are you curious if your city's water supply is fluoridated? If so, click here for information about your town (provided by the US Centers for Disease Control and Prevention).

Take a look at our Fluoridation USA infographic!

Fluoride precautions.

As beneficial as the use of fluoride can be, it must be used judiciously. For example, if young children ingest too much fluoride during that time frame when their teeth are developing, a type of tooth staining termed dental fluorosis can result.


A bottle of fluoride oral rinse.

How does fluoride help to prevent tooth decay?

Fluoride combats cavity formation in three ways:

1) Fluoride promotes tooth remineralization.

Researchers have discovered that fluoride enhances the tooth remineralization process.

(Remineralization is a little bit like "tooth decay in reverse." If you're not already familiar with this important phenomenon you really should use the link above to learn more about it.)

Here's how fluoride works.

  • Fluoride, drawn from a person's oral fluids (saliva), will adsorb onto the surface of a tooth where demineralization (tooth decay formation) has occurred.
  • The presence of this fluoride, in turn, actually attracts other minerals (such as calcium) to the area, thus helping to speed up the rate, or degree, to which remineralization (reformation of tooth mineral) will occur.

2) Fluoride helps to make a tooth more decay resistant.

Amazingly, the new tooth mineral that's created during remineralization when fluoride is present is actually "harder" than the tooth was originally.

Teeth are generally composed of the minerals hydroxyapatite and carbonated hydroxyapatite. The tooth mineral that is created during the remineralization process when fluoride is present is fluorapatite.

Fluorapatite is "harder" than other tooth minerals, in the sense that it is more resistant to damage caused by acids (demineralization). So, astoundingly, not only does fluoride promote the tooth's remineralization but it also helps to create a tooth surface that is even more resistant to the formation of tooth decay.

3) Fluoride helps to inhibit acid creation.

Dental researchers have found that fluoride acts to inhibit the rate at which the bacteria living in dental plaque are able to produce acids

This is because fluoride disrupts the bacteria's ability to metabolize sugars. And the less sugar that the bacteria can consume, the less acidic tooth-demineralizing waste products they will produce.

Tips about preventing tooth decay -
Fact - Tooth remineralization, a process that can help to repair the damage caused by tooth decay, is aided by the presence of fluoride. To receive this benefit, it must be present in a person's saliva.

Cavity prevention suggestions :

  • Drinking fluoridated tap water throughout the day makes a better choice than unfluoridated bottled water.
  • Make sure your toothpaste contains fluoride, so you get an extra exposure every time you brush.
  • Look for toothpastes that have the American Dental Association's (ADA) "Seal of Approval." This seal indicates that the ADA has evaluated the product and found its fluoride content to be appropriate.

Fluoride side effects - Dental fluorosis.

Teeth showing bands of fluorosis stains.

Dental fluorosis is a condition that results in tooth staining. It is caused by the chronic ingestion of too much fluoride during that time period when a child's tooth enamel is forming.

Types of fluorosis.

  • The vast majority of dental fluorosis that occurs in the United States is a mild form characterized by the appearance of chalky-white lines, or opaque-white patches, in a tooth's enamel.
  • More severe forms of fluorosis can occur. In extreme cases, the affected areas have a yellow or brown discoloration. And may result in tooth-surface pitting.

[Here's an Animated-Teeth.com digital smile makeover that illustrates the treatment of fluorosis.]

It's young children who are at risk.

Dental fluorosis only occurs if excessive amounts of fluoride are ingested (swallowed) over that time period when a child's tooth enamel is forming.

That means the most critical years for the risk of fluorosis lie between birth and age 6 or 7. But because the staining forms while the teeth are still developing, it's not visible until the affected teeth have come in, which is typically between the years 6 through 12.

Swallowing toothpaste is often the source of the problem.

Small children, especially those younger than age 6, may not be able to reliably spit out when brushing. And as a result, they may end up swallowing essentially all of the toothpaste that's been placed on their brush. If the one they're using is fluoridated, this activity may cause fluorosis.

The following suggestions can help to minimize a child's risk.

  • Children should be given instructions about how to properly brush and rinse. So to help them avoid swallowing toothpaste, they should be supervised when brushing.
  • Read your toothpaste's instructions. In most cases, only a small amount is needed such as a dab the size of a green pea. Fluoridated toothpaste should always be dispensed by an adult, not the child.
  • In most cases, unfluoridated tooth cleanser should be used with children 2 years and under. Ask your dentist for their recommendation.
  • Store fluoridated toothpaste out of the reach of children (some kids like the way it tastes and eat it).
  • When purchasing fluoridated toothpaste, look for one that has the American Dental Association's (ADA) "Seal of Approval."

Fruit drinks may be the culprit too.

Bottled juices and juice-flavored drinks manufactured with water can have fluoride levels that significantly exceed the 0.7 to 1.2 ppm (parts per million) that are considered appropriate and optimal.

Dental Caries
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