Consultations & Comments
The "Quick Take" on water fluoridation states that "fluoride prevents caries primarily after tooth eruption" (CONSULTANT, March 2001, page 472). Certainly, toothpastes, rinses, and gels that contain 1000 to 1500 ppm of fluoride achieve a temporary benefit as posteruptive topical treatments. However, the primary benefit of fluoridated water is the incorporation of fluoride into the enamel-a process that begins before eruption and that lasts for the life of a tooth.
In infants and children, the 1 ppm of fluoride in fluoridated water can be absorbed without causing fluorosis in the permanent teeth-which develop for 6 or more years before eruption. Human and animal studies have shown that the amount of fluoride present during the earliest phase of tooth development primarily determines how much fluoride is incorporated into the enamel during the final phase of mineralization. The classic fluoridation trials of the 1940s and 1950s in children showed that the earlier the ingestion of fluoride began, the more resistant to caries were the permanent teeth. The incorporation of near-maximum, subfluorosing amounts of fluoride results in teeth that have a smooth occlusal surface and enamel that has a tight, dense crystallinity with high resistance to acid dissolution.
Six trials examined the effect of prenatal exposure to fluoridated water and found that resistance to caries was improved in the primary teeth that start to develop at the twelfth week in utero and in the 6-year permanent molars that begin to develop around the fifth month.1 Ten studies demonstrated that prenatal fluoride tablet supplementation can virtually eliminate the "cavity-prone years of childhood." A once-a-day fluoride supplement better overcomes maternal loss of fluoride, which was formerly believed not to cross the placental barrier.1
The Food and Nutrition Board of the National Academy of Sciences recently recommended that pregnant women ingest a minimum of 3 mg/kg/d of fluoride and that infants and children ingest 0.05 mg/kg/d.2
—William Darby Glenn III, MD
South Miami, Fla