Bulletin #743

January 10, 2006

Dear All,

I am loathe to send out more than one bulletin a day, but as this pertains directly to information in the last bulletin, I felt it was important to circulate this clarification about the age range in which children are vulnerable to dental fluorosis on the PERMANENT teeth.

In response to FAN bulletin 742, webmaster Michael Connett writes:

“It has long been a misnomer that exposure to fluoridated water during infancy only effects the fluorosis risk of baby teeth (“primary teeth.”) This is not true.

For example, in August of 2006, researchers at the University of Iowa published one of the most comprehensive investigations on this subject. More specifically, they investigated which of the first four years of life cause the greatest risk for developing fluorosis on the PERMANENT teeth. The research team, which is led by Stephen Levy, found that fluoride exposure during the 1st year of life presents the greatest risk for developing fluorosis on the permanent teeth. The permanent teeth investigated were the upper front two teeth.

In other words, fluoride exposure during the first year of life presents a higher fluorosis risk to the upper-front permanent teeth than either the 2nd, 3rd, or 4th years of life.

This does not mean, however, that the 2nd, 3rd, or 4th years of life do not also increase fluorosis risk. Indeed, the Iowa study found that the risk of a child developing fluorosis on the permanent teeth was significantly increased by exposure during each of these years. Perhaps most importantly, was the study’s finding that the risk of getting fluorosis on permanent teeth was greatest if the child had been exposed to elevated fluoride for each of their first 4 years of life. In other words, a child exposed to fluoridated water for each of their first 4 years of life would have a greater risk of getting permanent fluorosis than a child exposed only during their first year.

In this regard, ADA’s advisory that children under 1 should not drink fluoridated water should indeed be extended to at least age 4, if fluorosis on the permanent teeth is to be avoided.

Finally, it bears emphasizing that this new study from Iowa is supported by a number of previous studies. I have included excerpts of them below (The first excerpt is from the Iowa study).”

Mike

Don’t forget that our web page has a great deal of information on dental fluorosis and other health effects caused by fluoride in our health data base. See

Paul Connett

“[F]luoride intakes during each of the first 4 years were individually significantly related to fluorosis on maxillary central incisors, with the first year most important (P Our results suggest that breastfeeding infants may help to protect against fluorosis. This is consistent with other studies that suggest that consuming infant formula reconstituted with tap water increases the risk for dental fluorosis. Importantly, this study shows that the protective effect of breastfeeding is important not only in fluoridated communities but also in nonfluoridated areas. Parents should therefore be advised that they may be able to protect their children from dental fluorosis by breastfeeding their infant and by extending the duration for which they breastfeed.”
    SOURCE: Brothwell D, Limeback H. (2003). Breastfeeding is protective against dental fluorosis in a nonfluoridated rural area of Ontario, Canada. Journal of Human Lactation 19: 386-90.

    “The findings of this investigation suggest that nearly 10 percent of the enamel fluorosis cases in optimally fluoridated areas could be explained by having used infant formula in the form of a powdered concentrate during the first year.”
   SOURCE: Pendrys DG. (2000). Risk of enamel fluorosis in nonfluoridated and optimally fluoridated populations: considerations for the dental professional. Journal of the American Dental Association 131(6):746-55.

    ”The findings indicate that early mineralising teeth (central incisors and first molars) are highly susceptible to dental fluorosis if exposed to fluoride from the first and – to a lesser extent – also from the 2nd year of life.”
   SOURCE: Bardsen A, Bjorvatn K. (1998). Risk periods in the development of dental fluorosis. Clinical Oral Investigations 2:155-160.

    ”There was a strong association between mild-to-moderate fluorosis on later forming enamel surfaces and infant formula use in the form of powdered concentrate (OR=10.77, 95% CI 1.89-61.25).”
   SOURCE: Pendrys DG, Katz RV. (1998). Risk factors for enamel fluorosis in optimally fluoridated children born after the US manufacturers’ decision to reduce the fluoride concentration of infant formula. American Journal of Epidemiology 148:967-74.

    ”[T]he odds ratio of fluorosis on enamel zones that began forming during the first year of life was 8.31 (95% CI = 1.84, 38.59) for children exposed since birth or during the first year of life relative to those exposed after 1 year of age. The odds that a child had a maxillary central incisor with fluorosis were 5.69 (95% CI = 1.34, 24.15) times higher if exposure occurred during the first year of life compared with exposure after 1 year of age. Only those exposed to the high-fluoride water during the first year of life developed fluorosis on the mandibular central incisors… The first year of life was a significant period for developing fluorosis on the mandibular and maxillary central incisors.”
   SOURCE: Ismail AI, Messer JG. (1996). The risk of fluorosis in students exposed to a higher than optimal concentration of fluoride in well water. Journal of Public Health Dentistry 56:22-7.

    ”It appears that, at least under some circumstances, high intakes of fluoride during the early months of life may make the difference between developing or failing to develop dental fluorosis. A study conducted in Sweden of 12- and 13-year-old children who had lived since birth in a community with 1.2 ppm of fluoride in the drinking water demonstrated that dental fluorosis was less common in those who had been breast-fed during the first 4 months of life than in those who had been fed powdered formulas reconstituted with tap water (Forsman, 1977). A somewhat similar study in the United States demonstrated that among 7- to 13-year-old children (most of them living in a community with fluoride concentration of the drinking water 1 mg/L), the prevalence of mild enamel fluorosis was significantly greater in those who had been fed concentrated liquid formula diluted with tap water during the first 3 months of life than in those who had been breast-fed during this time (Walton and Messer, 1981). It seems reasonable to conclude that the lower prevalence of fluorosis of the permanent teeth of individuals who were breast-fed during the early months of life is related to the low fluoride concentrations of human milk - concentrations less than 7 ug/L regardless of the concentration of fluoride in the women’s drinking water.”
   SOURCE: Ekstrand J, et al. (1994). Absorption and retention of dietary and supplemental fluoride by infants. Advances in Dental Research 8:175-80.

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