Fluoride and Water

Keeping your child's teeth healthy requires more than just daily brushing. During a routine well-child exam, you may be surprised to find the doctor examining your child's teeth and asking you about your water supply. That's because fluoride, a substance that's found naturally in water, plays an important role in healthy tooth development and cavity prevention.

What Is Fluoride?

Fluoride exists naturally in water sources and is derived from fluorine, the thirteenth most common element in the Earth's crust. It is well known that fluoride helps prevent and even reverse the early stages of tooth decay.

Tooth decay occurs when bacteria - found in the plaque that dentists try so hard to get rid of - break down sugars in food. This process produces damaging acids that dissolve the hard enamel surfaces of teeth. If the damage is not stopped or treated, the bacteria can penetrate through the enamel to the underlying tissues of the teeth, causing cavities (also called caries). Cavities weaken teeth and cause pain, tooth loss, or even widespread infection in the most severe cases.

Fluoride combats tooth decay in two ways. It strengthens tooth enamel, a hard and shiny substance that protects the teeth, so that it can better resist the acid formed by plaque. Fluoride also allows teeth damaged by acid to repair, or remineralize, themselves. Fluoride cannot repair cavities, but it can reverse low levels of tooth decay and thus prevent new cavities from forming.

Though fluoride benefits adults, it is especially critical to the health of developing teeth in children. And despite all the good news about dental health, tooth decay remains one of the most common diseases of childhood. According to 2000 statistics from the U.S. Surgeon General, more than half of children ages 5 to 9 years have had at least one cavity or filling, and tooth decay has affected 78% of 17-year-olds.

Fluoride and the Water Supply

As of 2002, the Centers for Disease Control and Prevention (CDC) statistics show that almost 66% of the U.S. population receives fluoridated water through the taps in their homes. Some communities have naturally occurring fluoride in their water; others add it at water-processing plants.

Some parents purchase bottled water for their children to drink instead of tap water. The growing bottled water industry claims that bottled water is safer, purer, mineral-free, and better tasting, and that may be true in some cases. But most bottled waters also lack fluoride. Fluoridated bottled water is one exception - it can sometimes be found in the baby-food aisle at the grocery store, usually labeled as baby water or nursery water.

Your child's doctor or dentist may know whether local water supplies contain adequate levels of fluoride (between 0.7 and 1.2 parts fluoride per million parts of water). If your water comes from a public system, you could also call your local water authority or public health department, or check online at the Environmental Protection Agency's (EPA) database of local water safety reports. If you use well water or water from a private source, fluoride levels should be checked by a laboratory or public health department.

The Controversy Over Fluoride

You may have heard that the addition of fluoride to the water supply is dangerous and damaging. Some advocacy groups publish reports on the hazards of fluoridation, and they point to toxicity warnings on toothpaste, concluding that any substance needing such careful dosage must be dangerous.

In response to claims that water fluoridation is dangerous, the National Institutes of Health (NIH) reviewed research on dental cavities prevention and public policy, including fluoridation. It agreed with antifluoride activists that many studies in this area are of poor quality. However, the NIH panel concluded that the unevenness of research does not invalidate the clear benefits of fluoride. The NIH believes that the dramatic reductions in tooth decay in the past 30 years are due to fluoridation of the water supply, and parents and health professionals should continue to ensure that kids receive enough fluoride to prevent cavities.

Your Child's Fluoride Needs

So how much fluoride does your child need? In general, children under the age of 6 months do not need fluoride. Your child's 6-month checkup offers a great chance to discuss fluoride needs with a health professional.

If you live in a nonfluoridated area, your child's doctor or dentist may prescribe fluoride drops, tablets, or vitamins after your baby is 6 months old. The American Academy of Pediatrics recommends that these fluoride supplements be given daily to children between the ages of 6 months and 16 years. The dosage will change as your child grows. Only children living in nonfluoridated areas or children who drink only nonfluoridated bottled water should receive supplements.

What about toothpastes, mouth rinses, and other products that contain fluoride? Here are a few tips for parents:

• Because children younger than 3 can't spit effectively, they may swallow too much toothpaste while brushing, and should be helped with their twice-daily brushings.
• Ask your child's dentist about the type of toothpaste your child under 3 should use. Many dental professionals recommend using toothpastes specially formulated for infants and toddlers.
• Children over age 3 should use a fluoride-containing toothpaste that carries the American Dental Association's (ADA) seal of acceptance.
• Kids should use only a pea-sized amount of toothpaste and spit out as much as possible after brushing. Even a small amount of toothpaste supplies enough fluoride for tooth protection but minimizes the chances of side effects from too much fluoride.
• Only mouth rinses clearly labeled "anticavity with fluoride" contain fluoride. They are regulated by the U.S. Food and Drug Administration (FDA) and are approved by the ADA. Children under age 6 should never use these rinses, as their spitting abilities haven't fully developed by that age. However, older children at high risk for tooth decay may benefit from fluoride-containing rinses. Your child's dentist can talk with you about risk factors such as a family history of dental disease, recent periodontal surgery or disease, or a physical impediment to brushing regularly and thoroughly.

Children over age 3 are at lowest risk for cavities if they regularly get fluoride from drinking naturally fluoridated or supplemented water, in addition to routinely brushing with fluoridated toothpaste. Consult your child's dentist before using any fluoridated mouth rinses or other products besides toothpaste.

Your family dentist or pediatric dentist (one who specializes in the care of children's teeth) is a great resource for information about your child's dental care and fluoride needs. A dentist can help you understand more about how fluoride affects the teeth, and once all of your child's primary teeth have come in, may further strengthen them by applying regular topical fluoride during visits.

Overexposure to Fluoride

If some fluoride is good, why not give children as much fluoride as possible? As with most minerals and vitamins, overexposure can be harmful. Most children get the right amount of fluoride through a combination of fluoridated toothpaste and fluoridated water or supplements.

Too much fluoride before 8 years of age can cause enamel fluorosis, a discoloration or mottling of the permanent teeth. This condition is unsightly but harmless and often can be treated with cosmetic procedures.

Most cases of fluorosis occur in children who take unnecessary daily fluoride supplements even though they brush regularly with fluoridated toothpaste and their home's tap water contains good levels of fluoride. Misuse of fluoride products, including rinses and toothpaste, also can contribute to fluorosis, but this is less common.

Very rarely, fluoride toxicity can occur when large amounts of fluoride are ingested during a short period of time. Children under age 6 account for more than 80% of reports of suspected overingestion. Although outcomes are generally not serious, fluoride toxicity sends several hundred children to emergency rooms each year.

Symptoms of fluoride toxicity may include nausea, diarrhea, vomiting, abdominal pain, increased salivation, or increased thirst. Symptoms begin 30 minutes after ingestion and can last up to 24 hours. If you suspect your child may have eaten a substantial amount of a fluoridated product or supplement, call the poison control center or 911.

Be sure to keep toothpaste, supplements, mouth rinses, and other fluoride-containing products out of children's reach or in a locked cabinet. You should also supervise your young child's toothbrushing sessions to prevent swallowing of toothpaste or other fluoridated products.

If you have any questions about your water's fluoride content, the fluoridated products your child uses, or whether your child is receiving too much or too little fluoride, talk to your child's doctor or dentist.

Reviewed by: and Garrett B. Lyons Sr., DDS
Date reviewed: September 2005
Originally reviewed by: