Journal of Dental Research, Vol 72, 883-890, Copyright © 1993 by International & American Associations for Dental Research Online Journals
An epidemiological assessment of the chronological distribution of dental fluorosis in human maxillary central incisors
R. W. Evans
School of Dental Science, University of Melbourne, Victoria, Australia.
The objectives of this study were: (1) to develop and test a new index, the
Chronological Fluorosis Assessment (CFA) Index, for measuring variation in
the chronological distribution and intensity of dental fluorosis, and (2)
to determine whether the new index was sufficiently sensitive for detection
of a decline in dental fluorosis corresponding to the reduction in the
waterborne fluoride level in Hong Kong. According to the CFA Index, the
cervical, middle, and incisal third divisions of the labial surface of a
maxillary central incisor crown are each classified into one of six
categories of an ordinal scale of fluorosis. Data from 1295 life-long
resident Hong Kong Chinese children exposed to known water fluoride
concentrations were analyzed. Fluorosis declined from incisal to cervical
in 41% of cases, and a reverse gradient was apparent in 29%. Overall,
fluorosis intensity was higher on incisal thirds than on both middle and
cervical thirds. However, when tooth thirds were regrouped according to
common 16-month developmental periods, in order to control for time-related
variation in fluoride concentration, the incisal-middle difference was of
reduced statistical significance, and both the incisal-cervical and the
middle-cervical differences became insignificant. A regression analysis of
CFA Index on cohort indicated a significant cohort-related fluorosis
decrease, in relation to cervical, middle, and incisal tooth thirds. It was
concluded (1) that fluorosed enamel which forms in chronological sequence
tends toward a uniform intensity, and (2) that the new index was
sufficiently sensitive for a decline to be measured in dental fluorosis in
Hong Kong.
