title: Dental fluorosis in primary teeth: a study in rural schoolchildren in Shaanxi Province, China.
abstract: OBJECTIVE
  The aim of this study was to assess the prevalence and severity of fluorosis in the primary dentition of 7-8-year-old Chinese schoolchildren in areas with fluoride concentrations in the drinking water ranging from 0.35 to 7.6 mg L-).
  
  
  METHODS
  Four hundred and seventy-two children from 13 different schools were divided into four groups according to the fluoride concentration of the drinking water: (A) <or=1.0 mg L-1; (B) 1.1-2.0 mg L-1; (C) 2.1-3.8 mg L-1; and (D) 7.6 mg L-1. Clinical examinations were made under field conditions, and dental fluorosis on the buccal surfaces of all teeth was recorded using the Thylstrup-Fejerskov Index (TFI).
  
  
  RESULTS
  The prevalence of dental fluorosis in primary teeth varied from 6.2% to 96.6% according to the fluoride concentration of the drinking water. The differences of median of TFI scores between all groups were statistically significant (P<0.001) except for groups B and C. No statistically significant difference in the severity of dental fluorosis was observed between genders. The second primary molars were most severely affected by dental fluorosis. Disregarding group A, TFI scores between 3 and 4 were most frequently recorded. Dental fluorosis was symmetrically distributed in both jaws.
  
  
  CONCLUSIONS
  Dental fluorosis is prevalent in the primary teeth of children living in areas supplied with drinking water with fluoride concentrations higher than 1.0 mg L-1. The primary teeth may act as biomarkers of fluoride exposure. The examination of primary teeth may give an early warning of this condition, and thus, provide a basis for intervention to prevent dental fluorosis in the permanent teeth.
authors.affiliation: Faculty of Dentistry, University of Bergen, Bergen, Norway. jianping_ruan@hotmail.com
authors.forename: J P
authors.initials: JP
authors.lastname: Ruan
authors.forename: Z L
authors.initials: ZL
authors.lastname: Wang
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Yang
authors.forename: A
authors.initials: A
authors.lastname: Bårdsen
authors.forename: A N
authors.initials: AN
authors.lastname: Astrøm
authors.forename: K
authors.initials: K
authors.lastname: Bjorvatn
mesh_terms: D017677:Age Distribution; D002648:Child; D002681:China / Q000453:epidemiology; D005260:Female; D009050:Fluorosis, Dental / Q000453:epidemiology* / Q000473:pathology; D006801:Humans; D008297:Male; D015995:Prevalence; D012424:Rural Population; D017678:Sex Distribution; D014094:Tooth, Deciduous; D014881:Water Supply