Timing of fluoride intake and dental fluorosis on late-erupting permanent teeth

Community Dent Oral Epidemiol. 2016 Feb;44(1):32-45. doi: 10.1111/cdoe.12187. Epub 2015 Jul 22.


Objective: Very few studies have examined the relationship between timing of fluoride intake and development of dental fluorosis on late-erupting permanent teeth using period-specific fluoride intake information. This study examined this relationship using longitudinal fluoride intake information from the Iowa Fluoride Study.

Methods: Participants' fluoride exposure and intake (birth to 10 years of age) from water, beverages, selected food products, dietary fluoride supplements, and fluoride toothpaste was collected using questionnaires sent to parents at 3- and 4- month intervals from birth to 48 months of age and every 6 months thereafter. Three trained and calibrated examiners used the Fluorosis Risk Index (FRI) categories to assess 16 late-erupting teeth among 465 study participants. A tooth was defined as having definitive fluorosis if any of the zones on that tooth had an FRI score of 2 or 3. Participants with questionable fluorosis were excluded from analyses. Descriptive and logistic regression analyses were performed to assess the importance of fluoride intake during different time periods.

Results: Most dental fluorosis in the study population was mild, with only four subjects (1%) having severe fluorosis (FRI Score 3). The overall prevalence of dental fluorosis was 27.8%. Logistic regression analyses showed that fluoride intake from each of the individual years from age 2 to 8 plays an important role in determining the risk of dental fluorosis for most late-erupting permanent teeth. The strongest association for fluorosis on the late-erupting permanent teeth was with fluoride intake during the sixth year of life.

Conclusion: Late-erupting teeth may be susceptible to fluorosis for an extended period from about age 2 to 8. Although not as visually prominent as the maxillary central incisors, some of the late-erupting teeth are esthetically important and this should be taken into consideration when making recommendations about dosing of fluoride intake.

Keywords: dental fluorosis; fluoride; fluoride intake; late-erupting permanent teeth.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Age Factors
  • Child
  • Child, Preschool
  • Female
  • Fluorides / administration & dosage
  • Fluorides / adverse effects*
  • Fluorosis, Dental / epidemiology*
  • Fluorosis, Dental / etiology
  • Humans
  • Infant
  • Infant, Newborn
  • Iowa / epidemiology
  • Logistic Models
  • Male
  • Surveys and Questionnaires
  • Tooth Eruption


  • Fluorides