Fluoride FAQ

Listed below are answers to commonly asked questions about fluoride, such as how it prevents tooth decay and why it is added to drinking water. Select a question to view the Canadian Dental Association’s (CDA) response.

1. What is fluoride?

Fluoride is a mineral found in nature. There is fluoride in the ocean, in the earth’s crust and in fresh water.

2. How does fluoride prevent tooth decay?

Fluoride works by making the outer layer of teeth (called tooth enamel) stronger. When the outer layer is strong, teeth are less likely to get cavities.

3. Where do I get the fluoride that prevents tooth decay?

Fluoride is provided mainly through drinking water, toothpaste, mouthwash, supplements (chewable tablets or drops), and other materials such as gels and rinses that may be applied during your visit to the dentist.

4. Why is fluoride added to the drinking water if it is available in other ways?

Adding fluoride to the water is the best way to provide fluoride protection to a large number of people at a low cost. That’s why many towns and cities put fluoride in the water in a controlled manner. The U.S. Centers for Disease Control recently named fluoridation of drinking water one of the 10 most successful public health measures in this century.

5. Who watches the fluoride levels in the drinking water?

Health Canada, through a joint federal/provincial committee, is responsible for watching the level of fluoridation in water supplies. In recent years, this committee has recommended that optimal levels of fluoride should be between 0.8 and 1.0 parts per million. This recommendation is based on the fact that many Canadians receive fluoride from many sources. As a result, some communities have lowered the level of fluoride in their water supply, in keeping with this recommendation.

6. What does “optimal levels” of water fluoridation mean?

Optimal levels of water fluoridation means finding the right balance between putting enough fluoride in the water to maximize the benefits of fluoride exposure while minimizing potential to contribute to dental fluorosis.

7. What is dental fluorosis?

Dental fluorosis occurs when white specks appear on a child’s teeth and is the result of a child getting too much fluoride. There is recent evidence that dental fluorosis among children is increasing. Most dental fluorosis is mild and barely visible. Dental fluorosis is not health threatening. It is mainly a cosmetic condition. In more severe cases, it can be easily treated by the dentist. Dental fluorosis is not a problem for older children or adults.

8. Why is dental fluorosis increasing?

Today’s young children are getting fluoride from a variety of sources, including drinking water and toothpaste, as well as foods and beverages that are made with fluoridated water. Children who show signs of dental fluorosis are generally being exposed to more fluoride than is required simply to protect their teeth.

9. Should we stop drinking fluoridated water because dental fluorosis is occurring?

Fluoridation of drinking water is still the most economical means of getting the proven protection that fluoride gives to teeth. Where fluoride has been added to municipal water supplies, there has been a marked decline in tooth decay rates. Children need fluoride protection while their teeth are developing. Adults also need it since the possibility of root cavities (tooth decay in the roots of the teeth) increases as they get older.

10. Should my child stop using fluoridated toothpaste?

Fluoridated toothpaste should be used twice per day with a minimum amount of water used to rinse the mouth after brushing.

As excessive swallowing of toothpaste by young children may result in dental fluorosis, children under 6 years of age should be supervised during brushing and only use a small amount (e.g. pea-sized portion) of toothpaste. Children under 3 years of age should have their teeth brushed by an adult using only a smear of toothpaste.

11. How do I know if my child is getting enough fluoride protection?

Your dentist is aware of the fluoride levels in the water in your area. He or she will try to estimate your child’s total fluoride intake and risk of cavities before prescribing fluoride supplementation. Supplementation, in liquid or chewable format, has proven useful in protecting patients at high risk of cavities or living in areas with high rates of cavities. Whatever your dentist decides, he or she will discuss any treatment option with you.

12. Are there any health risks associated with water fluoridation?

Many studies have looked at this topic. A U.S. committee on environmental health that has reviewed many of these studies has concluded that there is no link between cancer in humans and fluoride levels. And although some studies suggest that increased bone fragility may be linked to higher rates of exposure, we don’t know yet for certain as there are too many factors involved.

Like many natural substances, fluoride can be harmful in excessive amounts. Even table salt can be harmful if taken in large quantities. However, we are typically exposed to acceptable amounts of fluoride, even though it is available from a number of sources.