Combined Effect of Trace Elements and Fluorine on Caries
M. E. J. CURZON,* B. L. ADKINS,t B. G. BIBBY, and F. L. LOSEE
Eastman Dental Center, Rochester, New York 14603
Caries examinations of 251 children aged
12 to 14, from two Ohio towns that use
water supplies with high contents of boron
and strontium showed a mean DMFS score
of 3.56 compared to a score of 5.54 in a
control group of 338 children. Findings
suggest that the significantly lower caries
prevalence in the former group is related
to the boron and strontium content of the
water rather than a 0.2 ppm difference in
the fluorine level.
In conjunction with the early work of the
United States Public Health Service, which
established the relationship of fluorine to
caries, Blayney obtained spectrographic
analyses of the finished water supplies of
six Illinois towns for which fluorine and
dental caries figures had been compiled'
and sent them to us in 1967. A comparison
of the caries scores (DMFT) of the towns
with the content of trace elements in their
waters showed that with less caries there
was a consistent and progressive increase
of strontium, and, with two exceptions, increases of boron and fluorine. Copper, however, was higher in towns with a high caries
score. This information, and our demonstration of a statistically valid association
between low caries and high levels of strontium and boron in the waters of 35 states
for which information could be obtained,2
prompted the following investigation.
Materials and Methods
Caries examinations were conducted in
three Ohio communities, two of which contained high levels of strontium and boron
This work was supported, in part, by General Research Support Grant FR 5548 from the National
Institutes of Health, Bethesda, Md, and by the Office
of Naval Research, Project NR 105-384.
Received for publication May 4, 1969.
* University of Bristol Dental School, Bristol BSl 2,
LY, Eng.
t Department of Mathematics, University of Queensland, Brisbane, Queensland, Australia.
in the drinking water and soil products and
one of which contained low levels. The
communities, Fort Recovery, Delphos, and
Portsmouth, had, respectively, 5.30, 5.45,
and 0.20 ppm of strontium and 0.31, 0.39,
and 0.04 ppm of boron in their water. The
first two communities had 1.2 ppm and the
third 1.0 ppm of fluorine in their water.
Caries examinations were made of 12to 14-year-old children and included only
those who were lifelong residents of the
communities. Dental examinations were
made by one dentist, on school premises,
using a portable dental light and a standard
mouth mirror and explorer. A new explorer was used for each examination. Any
fissure or enamel surface in which the explorer stuck was regarded as carious; other
surfaces were listed as sound. The findings
were recorded on a Bodecker-type chart.
In all, 251 children were examined in Fort
Recovery-Delphos and 338 in Portsmouth.
Results
The findings of the examinations are
presented in Table 1. The average DMFT
and DMFS values for the high and low
trace element areas showed a consistently
lower caries prevalence rate for children
in the Fort Recovery-Delphos area compared with those in Portsmouth. The combined average DMFT score for male and
female children from Fort RecoveryDelphos was 2.25, which represents a difference of 26.0% from the Portsmouth
result of 3.04. The DMFT figure for
Portsmouth, incidentally, was 60.6% less
than that recorded before water fluoridation
in 1940. The average DMFS rate for Fort
Recovery-Delphos was 3.56, which was
35.7% less than the Portsmouth figure of
5.54.
STATISTICAL ANALYSIS.-Comparison of
the two areas on the basis of average DMF
rates can only be criticized because of the
526
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Vol 49 No. 3
TRACE ELEMENTS AND CARIES
527
TABLE 1
AVERAGE DMFT AND DMFS OF CHILDREN IN FORT RECOVERY-DELPHOS AND PORTSMOUTH
Age of
Males
No. of
Children
12
13
14
48
43
35
Average
Age of
Females
No. of
Children
12
13
14
44
43
38
Average
Combined Averages
Fort Recovery-Delphos
Means and SE
DMFT
DMFS
1.81 --.12
3.00 -i .16
1.98 -+.11
2.09 ± .14
1.96
3.23 +±.14
3.11 ±+.17
3.11
Fort Recovery-Delphos
Means and SE
DMFT
DMFS
1.68 ±+.12
2.67 ±+.12
3.29 ± .13
2.55
2.25
2.73 ±+.16
4.07 ±+.16
5.24 ±+.16
4.01
3.56
differences in age distributions of the
sample. The standard method of analysis
of variance for data classified according to
area, age, and sex requires that the number of subjects in each class be the same.
Since this was not true here, the nonorthogonal analysis of variance, as described by Rao3 was used to compare the
two areas. Distributions of DMFT and
DMFS were skewed, which is usually the
case for such data, and is particularly pronounced in instances where the average
DMF rates are small. A linear relationship
existed between the average DMF rate and
the standard deviation of observations for
a given age, sex, and area with both DMFT
and DMFS. For this reason, all observations were transformed before analysis,
using natural logarithms. Results of the
analysis are shown in Table 2. This combines the outcome of the four possible interactions of area, age, and sex, on DMFT
and DMFS. None of these was significant
when tested individually, and for every
interaction the mean square was remarkably
close to expectation. The significant difference between areas found with DMFT
No. of
Children
53
57
53
No. of
Children
68
55
52
Portsmouth
Means and SE
DMFT
DMFS
1.83 ±+.11
2.21 ±-.11
3.94 ±-.11
2.66
3.49 +±.14
4.37 ±+.13
6.77 ± .13
4.88
Portsmouth
Means and SE
DMFT
DMFS
2.43 ± .10
2.98 ±-.11
4.85 ± .11
3.42
3.04
4.25 ± .12
5.47 ± .13
8.90 ± .13
6.21
5.54
was even more pronounced with DMFS,
where the probability that the differences
observed could have occurred by chance
is exceedingly small. The absence of interaction indicates that this trend of lower
prevalence is true for all ages and both
sexes.
One further aspect was considered to incompatibility of the classes with respect to relevant factors not under test.
Although age has been taken into account
in the analysis, it is only partially an expression of time elapsed since tooth eruption. The relevance of this variable in
epidemiologic studies has been recognized
and demonstrated by such writers as Carlos
and Gittelsohn,4 Burch and Jackson,5 and
Takeuchi.6 To compensate for possible differences in eruption patterns and times in
the two areas, only those subjects whose
eruption of canines, premolars, and second
molars was complete were considered. This
procedure reduced the sample size, but the
number of remaining subjects was sufficient
for analysis. The results were almost identical to those reported for the whole sample
(Table 2); therefore, they are not reprosure
TABLE 2
ANALYSIS OF VARIANCE FOR THE NUMBER OF DMFT AND DMFS
DMFT
Source of
Variation
Degrees of
Between areas
Between ages
Between sexes
All interactions
Error
*
Signif-
Mean
F
Freedom
Square
Value
icance
Square
1
2
6.09
7.07
3.98
0.54
0.61
10.0
11.6
6.5
0.9
P < 0.01
P < 0.01
P < 0.05
NS*
16.48
8.25
2.65
1.01
0.98
1
7
577
Mean
DMFS
F
Value
16.8
8.4
2.7
1.0
Significance
P < 0.01
P < 0.01
NS
NS
NS, not significant.
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528
CURZON ET AL
duced here. The levels of significance
reached in all instances were the same.
Discussion
There appears to be reduced caries activity over the whole range of values of
DMFT and DMFS. For example, the percentage of males with ten or more DMFS
at Portsmouth was 19.6, compared with
7.1 at Fort Recovery-Delphos, and the
percentage of females with ten or more
DMFS at Portsmouth was 24.0 compared
with 16.0 at Fort Recovery-Delphos.
The fact that something other than fluorine in the water is responsible for the
lower caries in Fort Recovery-Delphos is
suggested by reference to the curve of the
relationship between the fluorine content
of the water and dental caries in 21 cities
(Dean, Arnold, and Elvovel) and the
curve for 57 cities (Striffler7). Neither of
these shows further reductions in caries
when the fluorine content increases from
1.0 to 1.2 ppm. More specifically related
to our study area, the Public Health Service figures for DMFT' at water fluorine
levels of 1.2 to 1.3 or higher show a
DMFT/100 children of 258 in Maywood,
281 in Aurora, 303 in East Moline, and
323 in Joliet, whereas at the same fluorine
level Fort Recovery-Delphos had a DMFT
of only 225. This comparison seems to justify the conclusion that in the Fort Recovery-Delphos area something besides fluorine is operating in some way to add to
the effectiveness in preventing caries.
J Dent Res May-June 1970
Conclusion
In view of the evidence presented, it is
reasonable to suggest that elevated concentrations of strontium and boron in water may contribute to lowering caries
activity.
References
1. DEAN, H.T.; ARNOLD, F.A., JR.; and ELvovE,
E.: Domestic Water and Dental Caries:
V. Additional Studies of the Relation of
Fluoride Domestic Waters to Dental Caries
Experience in 4,425 White Children, Aged
12-14 Years, of 13 Cities in 4 States, Public Health Rep 57:1155-1179, 1942.
2. LOSEE, F.L., and ADKINS, B.L.: A Study of
the Covariation of Dental Caries Prevalence
and the Multiple Trace Element Content
of Water Supplies, read before the 15th
Meeting of the European Organization for
Caries Research, Basle, Switzerland, July
9, 1968.
3. RAO, C.R.: Advanced Statistical Methods
in Biometric Research. New York: Wiley,
1952.
4. CARLOS, J.P., and GIrTELSOHN, A.M.:
Longitudinal Studies of the Natural History of Caries: II. A Life-Table Study of
Caries Incidence in the Permanent Teeth,
Arch Oral Biol 10:739-751, 1965.
5. BURCH, P.R.J., and JACKSON, D.: Periodontal Disease and Dental Caries, Brit Dent J
120:127-134, 1966.
6. TAKEUCHI, M.: Epidemiological Study on
Relation Between Dental Caries Incidence
and Sugar Consumption, Bull Tokyo Dent
Coll 3(2):96-111, 1962.
7. STRIFFLER, D.F.: Criteria to Consider
When Supplementing Fluoride-Bearing Water, Amer J Public Health 48:29-37, 1958.
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