Civil Engineering Reference
In-Depth Information
In 1938, Dean presented data demonstrating that dental caries were less prevalent
when mottled enamel occurred.
6
This led to extensive correlation studies on dental
caries versus fluoride levels in drinking waters throughout the United States. The re-
sults obtained, as summarized by Dean, are presented in Figure 20-1.
7
From this
information, and the dental fluorosis data, a dental caries-fluoride relationship evolved:
1. When the fluoride level exceeds about 1.5 mg / L, any further increase does not
significantly decrease the incidence of decayed, missing, or filled teeth, but does
increase the occurrence and severity of mottling.
2. At a fluoride level of approximately 1.0 mg / L, the optimum effect occurs, that
is, maximum reduction in caries with no aesthetically significant mottling.
3. At fluoride levels below 1.0 mg / L, some benefit occurs, but dental caries re-
duction is not great, and it gradually decreases as the fluoride levels decrease
until, as zero fluoride is approached, no observable improvement occurs.
It was noted earlier that all water supplies contain fluoride. Therefore, it can be
said that all water supplies are fluoridated. These ''naturally fluoridated'' waters with
1,100
-
-
1,000
-
900
-
800
-
700
-
600
-
500
-
400
-
300
-
200
-
100
0
0.5
1.0
1.5
2.0
2.5
3.0
Fluoride Content
Fig. 20-1.
Relationship between dental caries and fluoride level in drinking water (Reprinted
from
Journal AWWA,
Vol. 35, No. 9 (September 1943), by permission. Copyright
1943, Amer-
ican Water Works Association.)
