the f concentrations in plaque and in underlying enamel were determined in a sample of 99 schoolchildren aged 8.4 years ( s.d . = 0.37 ) , comprising four groups , exposed life-long to contrasting concentrations of f in the water ( range less than or equal to 0.12 ppm to 2.8 ppm ) and to supplements of 350 mg f/kg domestic salt .
C0011389
plaque
C0016327
f