Journal of Dental Research, Vol 70, 952-956, Copyright © 1991 by International & American Associations for Dental Research Online Journals
The severity of dental fluorosis in children exposed to water with a high fluoride content for various periods of time
T. Ishii and G. Suckling
Ministry of Health and Welfare, Tokyo, Japan.
Inhabitants of the Ikeno district of Japan were accidentally exposed to
drinking water containing 7.8 ppm fluoride (F) for 12 years, after which
water with 0.2 ppm F was substituted. Dental examinations of local
inhabitants revealed that only children aged seven years or less at the
introduction or aged 11 months or more at the removal of the high-F water
had fluorosis. Regular inspections were made of the 86 children between
those age limits. The severity of fluorosis in three tooth types (first
permanent molars, upper central incisors, and first premolars) was assessed
and related to the period of use of the high-F water. Continuous exposure
throughout tooth development resulted in severe changes in all three tooth
types. With limited exposure, the age at the beginning and at the end was
an important factor in determining the severity of the fluorosis. The
pattern of change from normal to severe fluorosis differed in the three
tooth types, influenced by their respective times of formation. Two
'at-risk' periods for the production of moderate or severe fluorosis were
evident. One started at birth and ended early in tooth development, while
the other started later and ended at eruption. The duration of F exposure,
although determining the initial degree of fluorosis, did not influence the
rate of post-eruptive enamel loss.
