Water Can Be a Good Fluoride Source

As public health physicians, we’re a little disappointed when friends tell us that they’re drinking bottled water because they don’t trust the public water supply. Our friends aren’t aware that their switch to bottled water may be costing them protection against dental cavities that comes from the fluoride added to most public water supplies.

Although small amounts of fluoride are naturally present in the usual sources of drinking water, higher levels of this mineral are needed to provide maximum protection against dental cavities. To reach the optimal levels, small amounts of fluoride are added to the drinking water in a process known as fluoridation.

Fluoride prevents dental cavities by strengthening tooth enamel and making it more resistant to the destructive effects of acids in saliva. These acids are created when bacteria in the mouth break down the sugars and other carbohydrates in our diet. To a limited extent, fluoride even helps reverse tooth decay that has already started, because it can remineralize damaged areas of the enamel. The protective effect of fluoride can be obtained either by ingesting the mineral in food and water (or with fluoride supplements), or by applying it topically--directly on tooth surfaces.

Ingested fluoride is particularly beneficial to young children, because the mineral is incorporated into the structure of their teeth, offering a lifetime of protection. Older children and adults, whose teeth are already formed, still need to consume adequate amounts of fluoride, because this influences the amount of fluoride in their saliva. (Since teeth are constantly bathed in saliva, healthy fluoride levels provide additional protection against cavities.)

An overwhelming majority of health professionals support water fluoridation, and regular exposure to small amounts of fluoride is widely endorsed by public health authorities. Water fluoridation was begun more than 50 years ago in this country, although it did not begin in the city of Los Angeles until 1999. Individuals living outside L.A. should contact their water supplier or local public health department to determine if their drinking water is optimally fluoridated. (The U.S. Public Health Service recommends that water be fluoridated at 0.7 to 1.2 parts per million.)

Studies have shown that many brands of bottled water do not contain optimal levels of fluoride. If you prefer drinking bottled water, choose one that has been fluoridated; these are generally sold at supermarkets and through home-delivery services. Look for the fluoride content on the label of the bottle. If the label contains no such information, contact the company that bottled it. If you use a water filter at home, be aware that some types of water treatment systems and water filters significantly lower fluoride levels.

Whatever type of water you drink, topical fluoride (applied directly to the surface of the teeth) can also help strengthen and repair dental enamel.

For older children and adults, brushing twice a day with a fluoride toothpaste is a good way to help fight cavities. After a child’s first teeth appear, they should be brushed daily. But fluoride toothpaste should not be used before age 2 except on the advice of a dental professional. Only a pea-sized amount of paste should be applied to a child’s toothbrush, and the child should be encouraged to spit out any excess during and after brushing.

Children under age 6 should be closely supervised while brushing their teeth to keep them from swallowing the toothpaste. Keep toothpaste out of a child’s reach, and limit brushing to twice daily.

Mouth rinses containing fluoride are also available, but they are not recommended for children younger than 6.

Dental professionals may recommend topical application of a highly concentrated fluoride preparation, particularly for cavity-prone patients.

All fluoride-containing products must be used judiciously, however, as excessive ingestion of fluoride can cause problems, particularly in young children. When teeth are forming, high fluoride levels can cause teeth discoloration or dental fluorosis. This discoloration usually is so mild that even a dentist may have difficulty detecting it. In a small number of patients, however, the discoloration can be severe and associated with pitting of the tooth enamel. (Because most teeth have erupted by about age 6, older children and adults are not susceptible to this type of discoloration.)

The American Dental Assn. and the American Academy of Pediatrics recommend fluoride supplements for children between 6 months and 16 years of age in areas where the water is not fluoridated. If you have children and your water is not fluoridated, discuss the possible need for fluoride supplements with their doctor or dentist.

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Dr. Jonathan Fielding is the director of public health and the health officer for the Los Angeles County Department of Health Services. Dr. Valerie Ulene is a board-certified specialist in preventive medicine practicing in Los Angeles. They can be reached at ourhealth@dhs.co.la.ca.us. Our Health runs the second and fourth Mondays of each month.