Table 2

Various variables in FNB and FSB areas

FNB areasFSB areasp Values
Dental fluorosis
 Data collected/investigated villages (n/N)*1318/1404558/581
 Subjects (children)5485526931
 Age (years)10.07±1.4410.08±1.440.32
 Female sex (N/%)25395(46.52)12610(46.82)0.42
 Prevalence rate of dental fluorosis (N/%)27669(50.44)5121(19.02)<0.001
 Dental fluorosis index†1.090.40
 Fluoride content in urine (mg/l)‡2.31(1.41, 3.82)0.90(0.54, 1.51)<0.001
 Fluoride content in water (mg/l)‡2.17(1.66, 2.94)0.54(0.29, 0.77)<0.001
Skeletal fluorosis
 Data collected/suvey villages (n/N)*1152/1404470/581
 Subjects (adults)406298188400
 Age (years)42.36±16.7942.91±16.67<0.001
 Female sex (N/%)196526(48.37)92711(49.21)<0.001
 Prevalence rate of clinical skeletal fluorosis (N/%)43940(10.81)9082(4.82)<0.001
 Fluoride content in urine (mg/l)‡2.38(1.50, 4.07)1.05(0.69, 1.75)<0.001
 Fluoride content in water (mg/l)‡2.17(1.62, 3.05)0.53(0.35, 0.75)<0.001
  • FSB and FNB areas: fluoride-safe water supply project had been built and not been built in these areas.

  • *Only have dental fluorosis or clinical skeletal fluorosis in some villages; values are mean±SD for continuous variables.

  • †The variable was calculated as (questionable number×0.5+very mild number×1+mild number×2+moderate number×3+severe number×4)/the total number of subjects.

  • ‡Log transformed before analysis, and data were expressed as M-estimator by Andrew and IQR (P25–P75).