Fluoride is often called nature’s cavity fighter, and for good reason. This naturally occurring mineral helps prevent tooth decay by making the surface of our teeth (known as tooth enamel) stronger and more resistant to cavities.

How exactly does fluoride work?

Cavities are caused by bacteria that live in our mouths. They feed on leftover food they find there, including sugary foods and drinks. When these bacteria consume sugars, they release acids that attack tooth enamel. Over time, damage to this protective outer layer of our teeth sets the stage for tooth decay.

Fluoride helps fight cavities by repairing the damage these acids can do to our teeth. The repair process is called remineralization.

How fluoride protects a child’s teeth from the very start

When infants are born, their baby (primary) teeth are already present in their jaws. Even before teeth break through the gums, they benefit from fluoride in the food and drink a child takes in. These early doses of fluoride strengthen the enamel on baby teeth, making them more resistant to cavities. (This is known as a systemic benefit.)

As a child’s primary teeth come in, fluoride helps rebuild any damage that happens when cavity-causing bacteria release acids in the mouth. This is why it’s important for children to use fluoride toothpaste and drink plenty of tap water, which usually contains fluoride.

Using fluoride toothpaste or getting a special fluoride treatment at the dentist’s office puts fluoride on the surface of a child’s teeth, creating a topical benefit. Also, the fluoride children get from foods and drinks becomes part of their saliva, bathing their teeth in tiny amounts of fluoride that help keep enamel strong and healthy.

How do we know fluoride is safe and effective?

For more than 70 years, the best scientific evidence has shown that adding fluoride to community water supplies is safe and effective. More than 100 health organizations recognize the cavity-fighting benefits of fluoridated water, including the World Health Organization, the American Medical Association, the Centers for Disease Control and Prevention and the American Dental Association.

Studies show that fluoride in water is especially helpful in fighting childhood cavities. In fact, one study revealed that children who live in communities without fluoridated water are three times more likely to end up in the hospital needing dental surgery.

Research also shows that fluoride in local water systems prevents at least 25% of tooth decay in people of all ages. Better dental health helps save money, since when more people need treatment for cavities, we all pay in the form of higher insurance premiums and taxes. In fact, the average lifetime cost per person of adding fluoride to local water supplies adds up to less than the cost of a single dental filling.

How much fluoride is added to local water supplies?

Fluoride is a natural element found in groundwater and our oceans. When we add fluoride to drinking water, we are adjusting it to the level that science shows will help prevent tooth decay. (The current recommendation is that communities adjust fluoride levels to 0.7 milligrams per liter of water.)

Adding fluoride to water is very much like adding vitamins and minerals to certain foods and drinks, a step that helps us get the nutrients we need. Examples include the iodine added to salt, vitamin D in milk or calcium added to orange juice.

Around 75% of the water supplies across the U.S. have added fluoride. Use this online map to find out if your local water is fluoridated.

Making fluoride toothpaste part of your cavity-fighting routine

Drinking water with fluoride is an important step in protecting your teeth. The ADA also recommends brushing with fluoride toothpaste. Here are healthy brushing tips for all ages.

Children under 3 years old: As soon as baby teeth appear, gently brush them with a small, soft-bristled brush and a little fluoride toothpaste (about the size of a grain of rice).

Children aged 3 to 6: Around this time, children begin learning to take care of their own teeth. They should brush twice daily for at least two minutes each time, using a pea-sized amount of toothpaste. Brushing in the morning and evening is usually best. Supervise your child to make sure they use the right amount and don’t swallow too much toothpaste. (Here’s a kid-friendly article on why fluoride is a superhero in fighting cavities.)

Older children and teens: As they grow, continue to encourage kids to use fluoride toothpaste in their twice-daily brushing routine. Here are tips for caring for children’s teeth and special advice for teens. Adults: Brush twice daily with fluoride toothpaste for at least two minutes each time, or as directed by your doctor or dentist. Brushing in the morning and evening is usually best.

Can mouthwash with fluoride prevent cavities?

Mouthwash that contains fluoride can help make your teeth more resistant to decay. If you are concerned about your dental health, ask your dentist if a mouth rinse with fluoride might be a good idea.

Children under age 6 should not use mouthwash unless it’s been recommended by a dentist. This is because younger children are more likely to swallow mouthwash than spit it out, since their swallowing reflexes are not fully developed.

Looking for mouthwash or toothpaste with fluoride? Here’s a list of dental care products that have earned the ADA Seal of Acceptance.

Fluoride treatments your dentist may recommend

Your dentist may apply fluoride directly to your teeth during a dental visit. This in-office treatment is often recommended for children to prevent early cavities. Adults may also have fluoride treatments in the dentist’s office. This topical fluoride may come in a gel, foam or liquid.

In some cases, dentists recommend fluoride supplements that come in tablets, lozenges or liquid drops. These prescription-only supplements may be helpful for children aged 6 months to 16 years who live in areas where fluoride is not added to local water supplies.

If you’re concerned that your child or teen isn’t getting enough fluoride to prevent cavities, ask your dentist, pediatrician or family physician for advice.