History of Water
Fluoridation
History of Water Fluoridation
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Two stories unfolded over more than half a
century:
 The
story of the harmful effects of fluoride in
large doses
 The story of dental benefits from small doses
Harmful effects of fluoride
The first important mention of the fluorosis
occurred in 1902 in El Paso County,
Colorado By Frederick S. McKay.
 McKay gave systematic attention to the
mottling and brown staining he found on
the teeth of many of his patients and
hypothesized it’s due to water supply.
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Harmful effects of fluoride
Harmful effects of fluoride
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By 1908 McKay studied enough cases and interested
enough colleagues to invite Dr. G. V. Black, then Dean of
Northwestern University Dental School to join him in the
study.
Black’s visit gained national attention to the phenomenon
and afterwards many cases were reported from other
parts of the country.
The name “Colorado brown stain” eventually gave way
to that of mottled enamel and the process soon became
associated with communal water supplies, usually from
deep wells – “deep well hypothesis”
Harmful effects of fluoride
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In Britton, South Dakota, in 1916 a study revealed
uniformed mottling of enamel among the children
brought up in the town since a new deep well had been
added to the communal water supply in 1898.
In 1925, citizens of Oakley, Idaho, where mottling was
prevalent, undertook to test the deep well hypothesis by
changing from a warm spring-water supply (artesian
water) to another shallower water supply:

In succeeding years, the children on the new water supply
developed no mottling, but the children brought up on the old
supply were not cured.
Harmful effects of fluoride
In 1925, McCollum, Bunting and others did
experiments on rats and found that rats,
fed in excess of fluoride developed
staining in incisors.
 At the time this wasn’t connected to stains
in enamel in humans .
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Harmful effects of fluoride
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Studies initiated in 1928 in Bauxite, Arkansas, led to the
final discovery that mottled enamel was associated with
fluoride in water
An exceptionally high incidence of mottling occurred in
this town, and the action upon the problem was more farreaching than usually because of presence of a plant of
Republic Mining and Manufacturing Company, a
subsidiary of the Aluminum Corporation of America.
Samples of Bauxite water eventually came to the
laboratory of H. V. Churchill, chief chemist for Alcoa, who
initiated spectrographic study.13.7 parts per million of
fluoride were found in the Bauxite water!
McKay was notified in 1931.
Harmful effects of fluoride
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Following this McKay arranged for reanalysis of
the water supplies in Britton, South Dakota,
Oakley, Idaho, and elsewhere.
Subsequent rechecking in many parts of the
United States soon developed a striking
correlation between mottled enamel and a
fluoride content of public water ranging from 2 to
13 parts per million.
At the same time Smiths in Arizona and Velu in
France made similar connection between
mottled enamel and fluoride, but this didn’t spark
as much interest.
Dental benefits of fluoride
The coexistence of low dental caries and
mottled enamel had excited comment from
McKay, even in the early years of his
investigation.
 After the discovery that fluoride correlated
with mottled enamel in 1931, several other
investigations also noted this inverse
relation.
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Caries
Dental benefits of fluoride
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Dr. H. Trendley Dean, on duty with the US Public Health
Service, made a thorough documentation of the degree
of mottled enamel and degree of caries at different
concentrations of fluoride.
As it became obvious that large reductions in caries
incidence were associated with the occasional
appearance of enamel opacities that were in no way
disfiguring, the term mottled enamel gave way to the
more exact term dental fluorosis.
1939 Cox and his coworkers suggested that supplying
optimum amount of fluorine during the tooth-forming
years could considerably reduce dental caries.
Dental benefits of fluoride
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1941-42. Dean HT (National Institute of
Health) reported on examination of 7,257
continuous-residence white children of 21
cities with differing amounts of fluorides in
their community waters.
Dental benefits of fluoride
Dental benefits of fluoride
Dental benefits of fluoride
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The studies established:
 Children
12-14 who have continuously, since
birth, used water with an optimal fluoride
concentration have, in general about twothirds less dental decay than children who
used fluoride-free drinking water.
 Lessened amount of dental caries follows the
use of a domestic water containing as low
as1.0 ppm of fluoride.
Three pilot studies (started 1945)
Newburgh, New York, with Kingston as a
control.
 Grand Rapids, Michigan, with Muskegon as
a control.
 Brantford, Ontario.

Newburgh – Kingston study
1942 Ast prepared a thesis on the cariesfluorine hypothesis in which he suggested
a plan to test this hypothesis.
 1943. A favorable report was made to
Edward S. Godfrey M.D., then the State
Commissioner of Health.
 Newburgh and Kingston were chosen for
the study
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Newburgh – Kingston study
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In March, 1944 the City Council of Newburgh
approved the water fluoridation
Following this many complaints were received
from local citizens in the span of one year:
 Discoloring
sauce-pans
 Digestive disturbances
 One complaint about water causing a denture to
crack.
Newburgh – Kingston study
But it was not until May 2, 1945 that the
water was fluoridated!
 Local paper carried an editorial which
pointed out to the people how some
persons can imagine all sorts of disabilities
from nonexistent causes.
 This ended the complaints.
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Newburgh – Kingston study
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Dental caries measurements (by one dentist) in 612 year olds for both cities (1944-45)
demonstrated close comparability
Annual clinical examinations in both cities (194455). Supplemented with roentgenograms (194950, 53-54, 54-55)
Several reports published. All showed
improvements in Newburgh and lack thereof in
Kingston
Newburgh – Kingston study
Newburgh – Kingston study
At the same time Pediatrics study was
conducted in the cities (with Kingston as a
control).
 Annual visits of children to the study clinic.
 After 10 years of water fluoridation no
differences of medical significance could
be found between the two groups of
children.
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Grand Rapids
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1945 Grand Rapids, Mich began water
fluoridation
Presented findings are from 1950
Study compares:
Rapids, Mich – water fluoridation
 Muskegon, Mich – control (similar climate)
 Aurora, Ill – naturally fluoridated water supply
 Grand
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Examinations of virtually the entire school
populations in continuous residence.
Grand Rapids
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Findings reported in:
 def
(decayed, extraction indicated, or filled)
for deciduous teeth
 DMF (decayed, missing, or filled) for
permanent teeth
Grand Rapids
Grand Rapids
Brantford – Sarnia – Stratford
1945 Brantford, ON began water fluoridation
 Final Survey, 1963
 Study compares:
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– water fluoridation
 Sarnia – negligible amount of fluoride in water
 Stratford – naturally fluoridated water supply
 Brantford
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Native, Continuously Resident 16-17-YearOld Children were examined (n = 356, 482
and 227 respectively).
Brantford – Sarnia – Stratford
All examinations done by the same
examiner
 Findings are presented in respect to (1) all
permanent teeth, and (2) permanent upper
incisors.
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Brantford – Sarnia – Stratford
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Indices used to measure caries-prevalence:
%
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of caries-free children
Permanent teeth
Upper incisors
 Tooth
mortality rate
 DMF (decayed, missing, filled):
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Permanent teeth per child
Permanent upper incisors
Brantford – Sarnia – Stratford
Brantford – Sarnia – Stratford
Brantford – Sarnia – Stratford
Brantford – Sarnia – Stratford
Dental benefits of fluoride
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The End 