The trace element fluorine is present in the body almost entirely in
bone and teeth. Because of its high reactivity, fluorine exists as its
anion fluoride. Fluoride's best known effect is to serve as a catalyst for
both the mineralization of developing tooth enamel prior to tooth eruption
and for remineralization of surface enamel. The combination of these
fluoride effects greatly reduces occurrence of dental decay (caries).
Denotal caries is an infectious disease caused by bacteria. When food is
ingested, oral bacteria multiply within their home (plaque) and produce
organic acids. Loss of tooth enamel accelerates as long as plaque pH is
less than 5.5. The presence of fluoride changes some of the tooth crystal
into a less acid-soluble crystal known as fluoropatite.
Diet recommendations: The Food and Nutrition Board of
the National Academy of Sciences has concluded that a fluoride intake of
0.05 mg/kg body weight, after the age of 6 months, provides an adequate
fluoride intake to reduce risk of dental decay. It is assumed that this
fluoride will come from a combination of food and water sources.
Food sources: The major source of fluoride is drinking
water. Seafood, some teas, and foods made with mechanically separated
chicken (baby food, canned meats, luncheon meats, and frankfurters)
contribute to total fluoride intake. Otherwise, most foods are very low in
fluoride.
Clinical uses: Regular comsumption of fluoride from a
community water supply plus regular use of fluoridated toothpaste can
significantly decrease prevalence of dental decay. Dietary fluoride
supplements are only recommended for children when the water supplies
fluoride at less than 0.3 mg/L. In this case, fluoride supplements of 0.25
mg/day for ages 0.5-3 years, 0.5 mg/day for ages 3-6 years, and 1 mg/day
for ages 6-16 years can be recommended. No dietary fluoride supplement is
recommended when water supplies fluoride at greater than 0.6 mg/L.
Under controlled experimental conditions, slow release administration
of fluoride (23 mg/day) plus calcium has been shown to stimulate new bone
formation in some individuals.
Toxicity: Children less than 8 years of age can
develop mottled tooth enamel (white horizontal lines with hypo-mineralized
areas susceptable to decay in extreme cases) if they ingest several times
more fluoride than recommended during tooth enamel formation. Swallowing
of fluoridated toothpaste by young children has been shown to be the most
prevalent cause of this problem.
