Advances in Dental Research, Vol 3, 154-160, Copyright © 1989 by International & American Associations for Dental Research
Changes in dental fluorosis following an adjustment to the fluoride concentration of Hong Kong's water supplies
R. W. Evans
In June, 1978, the fluoride concentration in Hong Kong water supplies was
reduced from 1.0 to 0.7 mg/L. The objectives of this study were (1) to
determine whether, as a result of this minor adjustment, a consequent
reduction in the prevalence and severity of dental fluorosis came about,
and (2) to determine whether dental fluorosis develops during enamel
secretion and primary mineralization or during the maturation stage of
enamel development. Dental fluorosis was assessed by Dean's community
fluorosis index (CFI) on upper central incisors in 2382 children aged from
7 (exposed to 0.7 mg/L only) to 13 years. The children were selected from
four districts served with drinking water by four different water treatment
stations. Differences in the distributions of dental fluorosis scores
across ages were significant in all districts. The susceptibility to
fluoride was assessed statistically through a series of analyses whereby
the fluoride concentration in the drinking water (both coincident with
enamel secretion and periods of enamel maturation) was correlated with CFI.
It was concluded (1) that CFI values were reduced following a minor
adjustment to the fluoride concentration in drinking water, (2) that dental
fluorosis develops during the maturation stage of enamel development, (3)
that the development of dental fluorosis may occur over a period of 16 to
24 months, commencing from 12 to 32 months following enamel secretion, and
(4) that Dean's index is a suitable instrument for monitoring the effects
on dental fluorosis of minor adjustments to the fluoride concentration in
drinking water.
