Fluoride Supplementation: The Ongoing Debate

Diane L. Markowitz, DMD, PhD


February 08, 2012

In This Article

Fluoride: Striking a Balance

Along with vaccination, control of infectious diseases, and motor vehicle safety, adding fluoride to US drinking water is considered one of the greatest public health achievements of the 20th century.[1] Fluoride was first added to water in 1945, a measure that was followed by a dramatic 50%-70% decline in the incidence of decayed, missing, or filled teeth (DMFT) in the United States.[2] Fluoridation was considered a safe and inexpensive way to prevent tooth decay, regardless of socioeconomic status or access to dental care.

The success of supplemental fluoride in reducing tooth decay and loss led to a search for additional modalities for delivery of fluoride, such as toothpastes, gels, mouth rinses, tablets, drops, and professionally applied fluoride treatments.[2] More than 65 years after fluoride was first added to community water supplies, the outcome of the "more is better" approach is an inability to accurately quantify the population's exposure to fluoride. Is it enough? Is it too much?

One year ago, after extensive review of the available evidence, the US Department of Health and Human Services (HHS) and the US Environmental Protection Agency (EPA) recommended that the maximum level of fluoride in drinking water be lowered to 0.7 mg/L (currently the minimum of the optimal range, 0.7-1.2 mg/L).[3] This step was taken to balance the benefits of supporting dental health in all children by preventing dental caries while limiting the risk for inducing fluorosis because of the unknown, and possibly excessive, exposure to fluoride from multiple combined sources.[4] Still, the practice of adding any fluoride at all to municipal water supplies has vocal opponents.

What Is Fluoride?

Fluoride is the reduced form of fluorine. It can occur as fluoroacetate, which is a fluorinated calcium phosphate that is common in silicates found in bedrock. Depending on the bedrock's mineral content and climate factors, rainwater filtration through these geologic formations can result in unsafe levels of naturally occurring fluoride in aquifers used for municipal drinking supplies.[5] Naturally occurring fluoride in ground water is not found in significant amounts in the overwhelming majority (96%) of US communities.[6]

Fluoride is incorporated into the mineral portion of tooth enamel, hydroxyapatite, as it develops. Hydroxyapatite becomes fluorapatite, which is more resistant to demineralization caused by bacterial acidification in oral plaque. Dietary fluoride incorporated in plaque has an antibacterial effect, slowing the growth of Streptococcus mutans, the primary cause of dental caries.[7]


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