The number of children with tooth discoloration from too much fluoride increased from the 1930s to the 1980s, according to a recent study, possibly because fluoride is in more oral-care products.

The tooth discoloration, called fluorosis or enamel fluorosis, ranges from white streaks or spots on the teeth to pitting and discoloration of the tooth’s outer layer, called the enamel. The condition is caused by ingesting too much fluoride during the first six to eight years of life.

Researchers say the study suggests that some changes may be needed to ensure that young children don’t get too much fluoride. They say changes that should be evaluated include:

* Teaching health-care providers to evaluate need to be more careful in prescribing fluoride supplements
* Manufacturing a toothpaste with lower fluoride levels for very young children
* Reducing the amount of fluoride in infant formula
* Reducing the amount of fluoride added to water supplies

Fluorosis usually is a cosmetic problem only, although treatment sometimes is needed in very severe cases.

The study, published in the February issue of the Journal of the American Dental Association, compared information from a national survey completed by the government in 1986 and 1987 with data collected in the 1930s. Researchers divided the children into three groups depending on the water fluoridation level:

* Optimally fluoridated refers to water supplies adjusted to fall between 0.7 and 1.2 parts per million (ppm) of fluoride.
* Naturally fluoridated refers to water supplies that contain at least 0.7 ppm of fluoride but are not adjusted by the city or local area. Naturally fluoridated water can contain as much as 4.0 ppm of fluoride, which is the maximum amount allowed by the U.S. Environmental Protection Agency.
* Suboptimally fluoridated water has less than 0.7 ppm of fluoride.

Children living in naturally fluoridated areas had the most fluorosis; 37.8 percent of children had the problem. In optimally fluoridated areas, 25.8 percent of children had some degree of fluorosis, while 15.5 percent of children living in suboptimally fluoridated areas had fluorosis.

In all categories, more children in the 1980s had fluorosis than children in the 1930s. The suboptimally fluoridated group showed the largest increase in fluorosis over the 50-year period.

The researchers say that some of the difference may be due to the increased availability of multiple sources of fluoride, including toothpastes, tablets, and mouth rinses. By 1983, 95 percent of toothpastes contained fluoride.

Also, between 6 percent and 8 percent of the children drinking either optimally or naturally fluoridated water reportedly received dietary fluoride supplements. “That should not have happened,” said Eugenio Beltran-Aguilar, D.M.D., M.P.H., an epidemiologist at the U.S. Centers for Disease Control and Prevention and an author of the study. “The person who prescribes supplements — physicians, pediatricians, dentists — should request measurements of the concentration of fluoride in the drinking water, and should prescribe [supplements] or not, based on the results.”

Water fluoridation between 0.7 and 1.2 ppm has been shown to reduce the risk of tooth decay.

“You cannot have zero fluorosis if there is fluoride in the water,” Beltran-Aguilar said. “Even in the optimally fluoridated communities, there was fluorosis.” He said that cases of moderate to severe fluorosis are due to multiple sources of fluoride. “If you have fluoridated water and a supplement and you swallow toothpaste, your chances of getting fluorosis, and more severe fluorosis, increase.”

The study looked at all levels of fluorosis, and many of the cases were mild. Only 1.5 percent of children in optimally fluoridated communities had moderate or severe fluorosis. Among the other children, 8.6 percent of those in naturally fluoridated communities and 0.6 percent of those in suboptimally fluoridated communities had moderate or severe fluorosis. Milder forms of fluorosis are not noticeable, Beltran-Aguilar said.

The study reinforces the idea that health-care providers and educators should make people aware of the effects of extra fluoride, he said. “Mothers should supervise the toothbrushing of their kids, and use only a pea-sized amount of toothpaste,” he said. Young children should only receive fluoride treatments if they do not receive optimal amounts of fluoride through the water supply.

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