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Caries Experience of Children One to Six Years Old in Two Oregon Communities (Corvallis and Albany)
Caries Experience of Children One to Six Years Old in Two Oregon Communities (Corvallis and Albany)
I. Effect of fluoride on caries experience and eruption of teeth
Gertrude Tank,* D D S , and Clara A. Storvick,f PhD , Corvallis, Ore
Pre- and postnatal exposure to water ad justed to 1.0 ppm of fluoride significantly reduced
the
caries rates of deciduous
teeth of Corvallis, Ore, children from the ages of one to six years when com
months old. Therefore, the purpose of this study was to investigate the effect o f pre- and postnatal exposure to a fluori dated water supply on the teeth of chil dren from one to six years old.
pared with the caries rates of teeth of children of Albany, Ore, where the water is fluoride-free. For those Corvallis chil dren who began consuming fluoridated water from 1 to 11 months postnatally, the
reductions
in
dental
caries
rates,
when compared with the caries rates of children of the control town, were less than for the Corvallis children who were exposed to fluoridated water both preand postnatally.
Information on the effect of fluoridated water on dental caries experience of very young children is extremely limited. Finn1 examined preschool children from the age of two years in Newburgh and Kingston, NY, for his prefluoridation study. No report has been found on subjects 12
M A T E R IA L A N D M E T H O D
Selection of Areas • Tw o Oregon com
munities were selected for the present study: Corvallis and Albany. Both towns are situated in the Willamette Valley and are comparable in climate, topography and population. Corvallis, however, has a water supply that was adjusted to 1.0 ppm of fluoride in January, 1953,2 where as Albany, which was chosen as the con trol town, has a water supply that is fluoride-free but similar to that of Cor vallis in total hardness in the form of cal cium carbonate.3’ 4 Selection of Subjects • The 246 children
selected for the study were normal and healthy white boys and girls from one to six years of age on their last birthday. O f these, 132 children were born and reared
78/750 • THE JO URNAL OF THE A M E R IC A N D E N T A L A S S O C I A T I O N
Tab le 1 • Number of examinations for Albany and Corvallis children during five years Age in years on last birthday Examination
Community
1
2
3
4
1
Albany Corvallis
33 93
31 26
26
10
23 2
1 1
2
Albany Corvallis
3 3
16 45
23 35
17 8
9 2
3 2
71 95
3
Albany Corvallis
3 2
4 21
12 20
11 9
5 2
35 54
4
Albany Corvallis
1 2
3 16
4 10
8 28
5
Albany C o rvallis,
1 _13
1 13
13 27
229 322
Total
Albany Corvallis
5
•H i 36 96
50 '73
in Corvallis, and 114 were bom and reared in Albany (Table 1). Their moth ers had used the municipal water during pregnancy. This fluoride intake during pregnancy may be a significant factor in caries inhibition in the offspring. A lthou gh Ericsson and M alm nâs5 found little change in fetal blood with an increased fluoride level in the maternal blood of four women, Gardner and others,6 Held,7 Feltman and Kosel,8 Zieg ler9 and Gedalia and others10 demon strated the accumulation of fluoride in the placenta and its transfer to the fetus. Gedalia and others11 found considerably higher concentrations of fluoride in fetal teeth in areas where the drinking water consumed by the mothers contained 0.5 to 0.6 ppm of fluoride than they did in the teeth of fetuses in areas where the water consumed by the mothers contained only 0.05 to 0.1 ppm of fluoride. Kraus12 showed that calcification o f deciduous teeth begins between the twelfth and fourteenth intrauterine week. For these foregoing reasons, the dental caries ex perience of a group of 42 additional Cor vallis children, bom from 1 to 11 months before fluoridation had been initiated, was studied separately. All children in the study had consumed the municipal water since birth and had not been absent from their respective areas for more than two
53 66
53 32
24 28
6
All ages 1)4 132
months in any year. Children who had received topical applications of fluoride or who were taking fluoride by prescrip tion were excluded, as were those children whose parents refused to allow roentgeno grams to be taken. The subjects were solicited by the sen ior author (G .T .) through talks on dental care for the preschool child. These talks were given in all schools of both com munities to members o f the ParentTeachers Association, to parents o f nurs ery school children, to various church groups and broadcast over the radio. The children came from all socioeconomic levels. In spite of all efforts to obtain sub jects, the number of children was lim ited because, by necessity, these small children had to be brought in for exam ination by their mothers on a voluntary basis. The children were examined in late spring or early summer over a period of five years. If, for some reason, a child was no longer available or eligible for the study, an attempt was made to replace him with another subject. N o child was accepted after he had reached five years of age. Therefore, it was not uncommon that many of the children were seen less than five times (Table 1). Oral Examination • Clinical and roent-
TANK— STORV1CK . . . VOLUME 69, DECEMBER 1964 • 79/751
genographic examinations were per formed in the dental office under good auxiliary light. Findings of these exam inations were recorded by the senior author, thereby limiting the variability of diagnosis.13 Chip blowers, mouth mir rors and explorers were used for the clini cal examinations. Oral roentgenograms were taken at each visit: two maxillary and mandibular anterior and four pos terior roentgenograms for the children from two to six years old, and two large inclusive maxillary and mandibular oc clusal roentgenograms for the youngest children. Ultraspeed films were used. The following symbols were used to designate caries experience in deciduous teeth: dmft (decayed, missing and filled teeth; teeth indicated for extraction were included in the designation of missing teeth), dt (decayed teeth), mt (missing teeth), ft (filled teeth) and ds (decayed surfaces). Methods o f observation were identical to those used by Tank and Storvick in a previous study.14 Stages in the progress o f dental caries as described by Massler and Schour15 were modified, and a quantitative dental decay severity
index was devised to measure the extent and depth of decayed surfaces or pulpal involvement based on clinical and roentgenographic examinations. Scores were as follows: 1— Superficial (caries in enamel). 2— Moderate (caries in enamel and su perficial caries in dentin). 3— Moderately severe (enamel under mined). 4— Severe (approaching pulp, enamel collapsed). 5— Pulpitis (caused either by deepseated caries or by trauma without caries). 6— Death of pulp (caused either by deep-seated caries or by trauma without caries). 7— Periapical infection (caused either by deep-seated caries or by trauma with out caries). The number of unerupted, erupted and exfoliated deciduous teeth also were de termined. Statistical Analysis • The means for all variables were calculated as the averages o f the means for each age. These means remove any effect o f age which might
Tab le 2 • Erupted and unexfoliated deciduous teeth per child for children with a fluoride-free water supply (Albany) and a fluoridated w ater supply (Corvallis) Deciduous teeth Girls
Boys
Both sexes
Community
N o. examined
Mean no. of teeth per child
N o. examined
Mean no. of teeth per child
N o. examined
Mean no. of teeth per child
1
Albany Corvallis
17 46
12.2 12.0
19 50
10.3 10.7
36 96
11.2 11.3
2
Albany Corvallis
27 38
17.6 18.0
23 35
18.3 18.1
50 73
17.9 18.1
3
Albany Corvallis
30 32
20.0 20.0
23 34
20.0 19.9
53 66
20.0 20.0
4
Albany Corvallis
29 13
20.0 20.0
24 19
20.0 19.9
53 32
20.0 20.0
5
Albany Corvallis
16 13
19.4 19.5
8 15
19.5 19.3
24 28
19.4 19.4
6
Albany Corvallis
10 16
16.9 18.0
3 11
15.3 17.0
13 27
16.5 17.6
All ages
Albany Corvallis
129 158
17.7 17.9
100 164
17.2 17.5
229 322
17.5 17.7
Age on last birthday
80/752 • THE JO U R N A L OF THE A M E R IC A N DENTAL ASSO C IA TIO N
Table 3 • Decayed, missing and filled deciduous teeth of children with a fluoride-free water supply (Albany) and a fluoridated w ater supply (Corvallis) Age on last birthday Community
1
2
3
4
5
6
All ages
Albany Corvallis
0.14 0.08
1.26 0.59
4.25 1.44
5.51 2.31
6.00 3.29
7.77 3.19
4.16 1.82
Per cent difference
Corvallis
-43
-5 3 *
-66*
-5 8 *
-4 5 *
-59*
-56*
Mean no. of decayed teeth per child
Albany Corvallis
0.14 0.08
1.26 0.59
3.89 1.30
4.96 2.00
4.96 2.00
5.38 1.70
3.43 1.28
Per cent difference
Corvallis
-4 3
-5 3 *
-6 7 *
-6 0 *
-60*
-68*
-6 3 *
Mean no. of missing teeth per child
Albany Corvallis
0 0
0 0
0.09 0
0.06 0
0.17 0
0.31 0
0.10 0
Per cent difference
Corvallis
-100
-1 0 0
-1 0 0
1 o o *
Mean no. of dmft per child
-1 00*
Mean no. of filled teeth per child
Albany Corvallis
0 0
0 0
0.32 0.11
0.68 0.41
1.00 1.32
2.69 1.70
0.78 0.59
0.14 0.09
1.34 0.56
5.08 1.45
7.28 2.66
8.83 2.89
10.92 3.00
5.60 1.78
Per cent difference
Corvallis
Mean no. of decayed surfaces per child
Albany Corvallis
-6 6
-4 0
+32
-3 7
-24
Per cent difference
Corvallis
-3 6
-5 8 *
-7 1 *
-6 3 *
-6 7 *
-7 3 *
-68*
Per cent of children caries-free (without dmft)
Albany Corvallis
89 97
54 79*
11 55*
8 38*
4 39*
0 33*
28 57*
Per cent of teeth caries-free (no dmft)
Albany Corvallis
99 99
93 97
79 93*
72 88
69 83
53 82
78 90*
— = reduction. + = increase. Calculated as follows: Corvallis-Albany Albany ’ Difference significant at the 5 per cent level.
otherwise have been present because the groups of children of different ages were unequal in size. The variation among subjects within an age group was used as an estimate of sampling error. “ F” or “ t” tests were used for all tests of hypotheses to determine statistical sig-
( 100 ).
nificance at the 5 per cent level o f prob ability. These tests were made by Lyle D. Calvin, professor of statistics, Oregon State University. RESU LTS
N o significant differences were found in the posteruptive tooth age of the decidu ous teeth of the subjects, either between the sexes or between the two communi ties (Table 2 ), although the Corvallis children showed a somewhat later ex foliation of their deciduous teeth.
D ecayed , missing and filled deciduous teeth of O regon children with a fluoride-free w ater supply (A lb a n y ) and a flu oridated w ate r supply (C o rv a llis)
Decayed, Missing and Filled Teeth • The dental caries experience in deciduous teeth of the children in Corvallis with its municipal water adjusted to 1.0 ppm o f fluoride and those in Albany with a fluoride-free water supply is shown in Tables 3 and 4 and the illustration. Pronounced reductions in dental caries
TANK— STORVICK . . . VO LUM E 69, DECEMBER 1964 • 81/753
experience occurred for the Corvallis children of all age groups compared with those o f Albany. Dental caries rates were reduced to the extent of 43 per cent at one year of age and 59 per cent at six years o f age for the mean number of dmft per child (Table 3 ). For all ages combined, the reductions were 56 per cent per child. Reductions for the Corvallis subjects were statistically significant for children of all ages except the one-year-old children. Decayed Teeth and Surfaces • Albany
children had a considerably higher num ber of decayed teeth and surfaces than the children of Corvallis (Table 3, 4 ). They had approximately three times as many decayed teeth and surfaces as the children in Corvallis. Caries Severity Index • Through the use of the numerical severity index (Table 6 ), it was found that the depth and ex tent o f the carious surfaces and the ex tent of pulpal involvements for all the Corvallis children, except for those chil dren one year old, were considerably less than for those of Albany. The differences were statistically significant for all groups. The contrast between the communities was especially pronounced for the chil dren from three to six years old and for all age groups combined, with reduction for the Corvallis children ranging from 64 to 76 per cent. Missing Teeth • Albany children had a
mean of 0.10 missing tooth per child (Table 3 ). None of the Albany children had had teeth extracted, and no extrac tions were indicated for children younger than three years of age. From then on, the number increased until at the age of six years 0.31 tooth per child was miss ing. None o f the Corvallis children had any teeth extracted, and no extractions were indicated. • None o f the children of either community had any teeth filled until they were three years old and very few until the age of five (Table 3).
Filled Teeth
Caries-Free Teeth • In Corvallis, 90 and, in Albany, 78 per cent o f the deciduous teeth of children from one to six years old were free from caries attack (Table 3, 4 ). The difference between the com munities was statistically significant. As was to be expected, the percentages of caries-free teeth gradually declined from the age o f one year and were lowest at the age of six years. This decline also was true for the prevalence of children with out past and present caries experience of their deciduous teeth (Table 3, 4 ). At one year of age, 89 per cent of the Albany and 99 per cent of the Corvallis children were caries-free. By the time these chil dren were six years old, none of the A l bany children were caries-free, and only 33 per cent of the Corvallis children were without caries. Differences between the
Table 4 • Decayed, missing and filled deciduous teeth of children one to six years old with a fluoride-free water supply (Albany) and a fluoridated w ater supply (Corvallis)
Mean no. of dmft per child
Boys
Girls
Both sexes
Albany Corvallis
4.31 1.80
3.87 1.78
4.16 1.82
Per cent difference
Corvallis
—58*
i Ch -px •*
Community
-56*
Per cent of teeth caries-free (no dmft)
Albany Corvallis
77 90*
78 90*
78 90*
Per cent of children caries-free (without dmft)
Albany Corvallis
28
27 59*
28 57*
— = reduction. *Difference significant at the 5 per cent level.
55*
82/754 • THEJOURNAL OFTHEAMERICAN DENTALASSOCIATION T a b le 5 • D e c a y e d , m issing a n d filled d e c id u o u s teeth o f ch ild re n o n e to six y e a r s old w ith n o e x p o s u re , w ith p o stn a ta l e x p o s u r e a n d w ith p r e - a n d p o stn a ta l e x p o s u r e to a flu o rid a te d w a te r su p p ly C o n su m p t io n o f flu o rid a t e d w a te r A lb a n y
C o r v a l lis
None
1 t o 11 m onths p o s tn a ta lly
C o r v a llis P re -a n d p o stn a ta lly
N o . o f ch ild re n
114
42
132
N o . o f e xa m in a tio n s
2 29
95
3 22
M e a n no. o f dmft p e r ch ild
4.16
2 .6 5 *
1 .8 2 *
M e a n no. o f dt p e r child
3.43
1 .5 8 *
1 .2 8 *
M e a n no. o f mt p e r child
0.10
0.19
0 .0 *
M e a n no. o f ft p e r child
0.78
0.88
0.59
M e a n no. o f d s p e r ch ild
5.60
2 .2 2 *
Per ce n t o f ch ild re n w ith c a r ie s -fr e e teeth (no dmft)
28
34
1 .7 8 * 57*
♦Difference significant at the 5 per cent level from Albany children.
children of both communities were sta tistically significant from the ages of two to six years and for all ages combined; 28 per cent of the Albany and 57 per cent of the Corvallis children were free from dental caries of their deciduous teeth. POSTN ATAL EXPOSURE TO FLUORIDATED W ATER
The dental caries experience of a sepa rate group of 42 Corvallis children, also one to six years of age, was studied (Ta ble 5). They were bom from 1 to 11 months before fluoridation had been ini tiated, but otherwise they fulfilled all the rigid criteria necessary to be included in the study. This group of children, how ever, was excluded from any of the other investigations included in this report. It was found that those Corvallis chil dren who were born before fluoridation had begun had a higher prevalence of dental caries of the deciduous teeth than those bom after fluoridation. Although the sample of children with only post natal exposure to fluoridated water was small and the difference in caries expe rience was not statistically significant, the
findings were consistent with results of some other investigations.8,11 The children with only postnatal expo sure to fluoridated water showed a lower prevalence of dental caries than those in the fluoride-free control town. The dif ferences in dental caries experience be tween the Albany children and those in Corvallis with only postnatal exposure to fluoridation were statistically significant except for differences in regard to missing and filled teeth. The results, therefore, show that chil dren bom from 1 to 11 months before fluoridation experienced a pronounced reduction in dental caries compared with children in the fluoride-free town of Al bany. Nevertheless, the results of this study indicate that more protection is given to the teeth of those Corvallis chil dren who were exposed to fluoridated water both pre- and postnatally. DISCUSSION
Variation in time of eruption and exfolia tion of deciduous teeth determines the length of exposure of those teeth to the oral environment and thus may affect dental caries experience4 but, in this
TANK—STORVICK . . . VOLUME 69, DECEMBER 1964 • 83/755 study, the differences in eruption and ex foliation time between the two commu nities were insignificant (Table 2). Comparison of dental caries experience with other long-term epidemiologic flu oridation studies could be made only for children from the age of four years because this is the youngest age group for which results have been published.16 Den tal caries activity of the Albany and Cor vallis children was high compared with the caries experience in fluoride-free and fluoridated areas reported elsewhere.2,16-20 This experience was true even when the additional 6 per cent of dmft and 12 per cent of ds found by roentgenographic ex amination were taken into consideration, a method used only in two of the other studies.17,18,20 Two reasons for the high caries r;ates for the Oregon children may be (1) the high susceptibility to dental caries found for children living in western Oregon2,4 and (2) the variability of di agnosis due to different methods and ex aminers.2,13 In spite of the high caries rates, reductions in dental caries experi ence for the Corvallis children of all age groups were significant when compared to those of Albany. Reductions in dental caries activity due to pre- and postnatal exposure to fluoridated water were higher for the four-year-old Corvallis children than for the four-year-old children stud ied by Arnold and co-workers16 in Grand Rapids, Mich. For the five- and six-yearold children, reductions were comparable to those found by Arnold and his co workers16 in Grand Rapids, by Hutton, Linscott and Williams19 in Brantford, Ontario, and by Ast and Chase17 in New burgh, NY. The quantitative dental caries severity index expresses in simple terms the extent and mean number of dental lesions per child, classified by age group and com munity (Table 6). This index or score is based on the results of clinical and roentgenographic examinations, and it reflects the extent, depth and number of carious surfaces and pulpal involvements. In the calculation of this index, data con-
T ab le 6 • Distribution o f the s e v e rity o f d e n ta l c a r ie s (d e c a y e d su rfa ce s) in d e c id u o u s teeth o f ch ild re n with a flu o rid e -fre e w a te r su p p ly (A lb a n y) a n d a flu o rid a te d w a te r s u p p ly (C o rv a llis)
A g e on last b irth d a y
T o ta l s e v e rity in d e x t p e r child A lb a n y
C o r v a llis
Per cent difference, C o r v a llis
1
0.14
0.14
2
2.68
1.38
-4 9 * -6 9 *
00
3
8.49
2.62
4
13.30
4.81
-6 4 *
5
19.29
6.14
-6 8 *
6
24.85
5.85
-7 6 *
All a g e s
11.46
3.54
-6 9 *
— = reduction. *Difference significant at the 5 per cent level. fN um ber of decayed surfaces X severity index number.
ceming filled surfaces as well as the de cayed surfaces represented by extracted teeth were not included because a filling may have extended into tooth surfaces which had not been decayed and because the number and extent of carious lesions in an extracted tooth were not known. It was shown that the difference in dental caries severity index between age groups was considerable and, for the Albany subjects, the increase in extent and num ber of decayed surfaces and untreated pulpal involvements per child was sta tistically significant for all ages, except for the one-year-old children when com pared with those of Corvallis. Savara and Suher21 studied the caries experience of children in Portland, Ore, where the water supply is not fluoridated. They found fewer children caries-free at the age of one year than were found in the present study, but they reported a con siderably higher percentage of caries-free children from the ages of two to six years than was found in Albany. This higher percentage was also found in various prefluoridation studies on children rang ing in age from two to five,1 five to six2 and six to eight years.20 In some of the postfluoridation reports,2,20 however, the percentage of children in comparable age
84/756 • THEJOURNAL OF THEAMERICAN DENTALASSOCIATION groups without past or present dental caries of their deciduous teeth was similar to that found in Corvallis in the present study. It was shown previously2 that the fluo ride ion has some caries-inhibitory effect on deciduous teeth, even when incorpo rated into the tooth structure either before eruption during the period of calcifica tion or after eruption. This caries-inhibi tory effect of the fluoride ion again was demonstrated in the present study. The even greater benefit of pre- and postnatal exposure to fluoridated water on the de ciduous teeth of children from the age of four years, found by a number of other investigators,2,8’14,20 again was substan tiated in this report. It also has been shown in the present study that children from the ages of one to three years also derive considerable benefits. Carlos, Gittelsohn and Haddon22 did not find any significant relation between ingestion of fluoridated water by gravid women and prevalence of dental caries in deciduous teeth of their offspring at the age of six years, whereas Feltman and Kosel8 presented evidence that fluoride ingested during the first and second tri mester of pregnancy passed the pla cental barrier, entered the fetal blood supply and consequently increased the resistance to dental caries of the decidu ous teeth of children ranging in age from 3 to 12 years. This, reduction in caries of deciduous teeth due to prenatal expo sure to fluoridated water in addition to postnatal consumption of it, when com pared with the effect of postnatal con sumption alone, was also consistent with the results of the present study. SU M M ARY AND CON CLUSION S
The effect of pre- and postnatal exposure to water from a supply adjusted to 1.0 ppm of fluoride on the dental caries ex perience in deciduous teeth of children from the ages of one to six years was in vestigated in a semi-longitudinal study. The dental caries experience in a separate
group of children who consumed fluori dated water from 1 to 11 months after birth also was determined. The following results were obtained: 1. Dental caries rates of the children were significantly reduced by pre- and postnatal exposure to fluoridated water when compared with the caries rates of the children whose water was fluoridefree. 2. Children with only postnatal expo sure to fluoridated water showed pro nounced reductions in dental caries rates when compared with the dental caries rates of children of the control town, but the reductions were less than those found for the children with pre- and postnatal exposure to a fluoridated water supply. This paper is the first in a series of articles on dental caries experience of O regon children one to six years of age in Corvallis with a fluoridated water supply and in Albany, where the water is fluoride-free. Two a d d i tional papers will be published in subsequent issues of T H E JO U R N A L . *Associate professor of nutrition research, nutrition research laboratory, School of Hom e Economics, O regon State University, Corvallis. tProfessor of foods and nutrition, nutrition research laboratory, School of Hom e Economics, O regon State University, Corvallis. 1. Finn, S. B. Second annual progress report on fluo ride investigations. New York D. J. 13:78 Feb. 1947. 2. Tank, G., and Storvick, C. A . Dental caries expe rience of school children in Corvallis^ Oregon, after 7 years of fluoridation of water. J. Pedlat. 58:528 April 1961. 3. Storvick, C . A., and Sullivan, J. H. Total hardness and fluoride content of O regon public water supplies. J. Am. W ater W orks Assoc. 42:589 June 1950. 4. Tank, G:, and olhers. Cooperative nutritional status studies in the western region. III. Variation in dental caries experience am ong children of five western states. Oregon State College, A g. Exp. Sta. Tech. Bui. 45:15, 1959. 5. Ericsson, Y., and Malmnas, C. L. Placental transfer of fluorine investigated with F18 in man and rabbit. Acta Obstet. Gynec. Scandinav. 41:144, 1962. 6. Gardner, D. E., and others. Fluoride content of placental tissue as related to fluoride content of drink ing water. Science 115:208 Feb. 22, 1952. 7. Held, H. R. Fluormedikation und Blutfluor. Schweiz, med. Wchnschr. 84:251 Feb. 20, 1954. 8. Feltman, Reuben, and Kosel, George. Prenatal and postnatal ingestion of fluorides— fourteen years of inves tigation— finaI report. J. D. M ed. 16:190 Oct. 1961. 9. Ziegler, E. Untersuchungen uber die Fluorierung der Milcn zur Cariesprophylaxe. Mitt. Naturwiss. Gesellsch. Winterthur 28:1, 1956. 10.^ Gedalia, I., and others. Placental transfer of fluorine in the human fetus. Proc. Soc. Exper. Biol. Med. 106:147 Jan. I96J. . II. Gedalia, I., and others. Fluoride content of teeth and bones of human foetuses. Arch. O ral Biol. 9:331 May-June 1964. 12. Kraus, B. S. Calcification of the human deciduous teeth. J A D A 59:1128 Dec. 1959. 13. Berggren, H., and Welander, Erik. Unreliability of caries recording methods. Acta Odont. Scandinav. 18:409 Dec. I960.
TANK—STORVICK . . . VOLUME 69, DECEMBER 1964 • 85/757 14. Tank, Gertrude, and Storvick, Clara A. Effect of naturally occurring selenium and vanadium on dental caries. J. D. Res. 39:473 May-June I960. 15. Massler, Maury, and Schour, Isaac. Atlas of the mouth and adjacent parts in health and disease. C hi cago, Am erican Dental Association, 1952, plate 9. 16. Arnold, F. A., Jr., and others. Effect of fluoridated public water supplies on dental caries prevalence. Pub. Health Rep. 71:652 July 1956. 17. Ast, D. B., and Chase, H. C. Newburgh-Kingston caries fluorine study. IV. Dental findings after six years or water fluoridation. Oral Surg., Oral M ed. & Oral Path. 6:114 Jan. 1953. 18. Ast, D. B.t and others. Newburgh-Kingston cariesfluorine study. XIV. Com bined clinical and roentgeno-
graphic dental findings after ten years of fluoride expe rience. J A D A 52:314 March 1956. 19. Hutton, W. L., Linscott, B. W., and Williams, D. B. Final report of local studies on water fluoridation in Brantford. Canad. J. Pub. Health 47:89 March 1956. 20. Hill, I. N., Blayney, J. R., and Wolf, W. Evanston dental caries study. XVI. Reduction in dental caries attack rates in children six to eight years old. J A D A 53:327 Sept. 1956. 21. Savara, B. S. and Suher, Theodore. Incidence.of dental caries in children I to 6 years of age. J. D. Res. 33:808 -Dec. 1954. 22. Carlos, J. P., Gittelsohn, A. M., and Haddon, W., Jr. Caries in deciduous teeth in relation to maternal ingestion of fluoride. Pub. Health Rep. 77:658 Aug. 1962.
Imagination and the Scientist • I n o rd e r to be u se fu l in science, im a g in a tio n m u st be co m b in e d w ith a keen sense fo r w h a t is im p o rta n t. T h i s assessm ent m ust, of necessity, be m a d e in stin c tiv e ly o n insufficient evide n ce at a tim e w h e n im p o rta n c e is n o t yet d e m o nstrab le . H e re , p e rh a p s m o re t h a n i n a n y o th e r respect, th e scientist m u st d e p e n d o n in n a te gifts. I t is v ir t u a lly im p o ssib le to teach im a g in a tio n . O n ly o u r v is io n fo r the im p o rta n c e o f t h in g s can be sh a rp e n e d t h ro u g h experience, b y tria l a n d error. T h i s d ep endence o f critica l ju d g m e n t u p o n expe rie nce e x p la in s w h y, i n the cou rse o f life, it takes so m u c h lo n g e r to d e v e lo p a sense o f v a lu e s t h a n to e x h ib it the la rg e ly in n a te p o w e r o f im a g in a tio n . T h e fla ir fo r the p o te n tia l p ra c tic a l o r theoretical im p o rta n c e of the t h in g s th a t w e im a g in e is n o t itse lf im a g in a tio n ; it is m e re ly a p re re q u isite fo r the selection, a m o n g in n u m e r a b le im a g in a ry pictures, o f those h a v in g sign ific a n t a p p lic a tio n s in reality. T h e c o m b in e d ac tiv ity o f first im a g in in g a n d then fix in g the im p o r ta n t aspects o f the im a g in e d p ic tu re o n to co n scio u s re a lity is th e ba sis o f creative t h o u g h t — the m o st e le v a tin g a n d sa tisfyin g a c tiv ity o f w h ic h the h u m a n m in d is capable. T h e act of scientific a n d artistic creation, m u c h lik e th a t of pro cre atio n , giv e s th e e n joym e n t o f release fr o m th e te n sio n s o f a ne e d— a h u n g e r — w h ich , w h e n appeased, leaves o u r w h o le b e in g d e lig h t fu lly flagge d b y th e sense o f fu lfillm e nt. Hans Selye, From Dream to Discovery, New York, M cG raw-H ill Book Co*, Inc., 1964, p. 44; 45.
I. Effect of fluoride on caries experience and eruption of teeth
Gertrude Tank,* D D S , and Clara A. Storvick,f PhD , Corvallis, Ore
Pre- and postnatal exposure to water ad justed to 1.0 ppm of fluoride significantly reduced
the
caries rates of deciduous
teeth of Corvallis, Ore, children from the ages of one to six years when com
months old. Therefore, the purpose of this study was to investigate the effect o f pre- and postnatal exposure to a fluori dated water supply on the teeth of chil dren from one to six years old.
pared with the caries rates of teeth of children of Albany, Ore, where the water is fluoride-free. For those Corvallis chil dren who began consuming fluoridated water from 1 to 11 months postnatally, the
reductions
in
dental
caries
rates,
when compared with the caries rates of children of the control town, were less than for the Corvallis children who were exposed to fluoridated water both preand postnatally.
Information on the effect of fluoridated water on dental caries experience of very young children is extremely limited. Finn1 examined preschool children from the age of two years in Newburgh and Kingston, NY, for his prefluoridation study. No report has been found on subjects 12
M A T E R IA L A N D M E T H O D
Selection of Areas • Tw o Oregon com
munities were selected for the present study: Corvallis and Albany. Both towns are situated in the Willamette Valley and are comparable in climate, topography and population. Corvallis, however, has a water supply that was adjusted to 1.0 ppm of fluoride in January, 1953,2 where as Albany, which was chosen as the con trol town, has a water supply that is fluoride-free but similar to that of Cor vallis in total hardness in the form of cal cium carbonate.3’ 4 Selection of Subjects • The 246 children
selected for the study were normal and healthy white boys and girls from one to six years of age on their last birthday. O f these, 132 children were born and reared
78/750 • THE JO URNAL OF THE A M E R IC A N D E N T A L A S S O C I A T I O N
Tab le 1 • Number of examinations for Albany and Corvallis children during five years Age in years on last birthday Examination
Community
1
2
3
4
1
Albany Corvallis
33 93
31 26
26
10
23 2
1 1
2
Albany Corvallis
3 3
16 45
23 35
17 8
9 2
3 2
71 95
3
Albany Corvallis
3 2
4 21
12 20
11 9
5 2
35 54
4
Albany Corvallis
1 2
3 16
4 10
8 28
5
Albany C o rvallis,
1 _13
1 13
13 27
229 322
Total
Albany Corvallis
5
•H i 36 96
50 '73
in Corvallis, and 114 were bom and reared in Albany (Table 1). Their moth ers had used the municipal water during pregnancy. This fluoride intake during pregnancy may be a significant factor in caries inhibition in the offspring. A lthou gh Ericsson and M alm nâs5 found little change in fetal blood with an increased fluoride level in the maternal blood of four women, Gardner and others,6 Held,7 Feltman and Kosel,8 Zieg ler9 and Gedalia and others10 demon strated the accumulation of fluoride in the placenta and its transfer to the fetus. Gedalia and others11 found considerably higher concentrations of fluoride in fetal teeth in areas where the drinking water consumed by the mothers contained 0.5 to 0.6 ppm of fluoride than they did in the teeth of fetuses in areas where the water consumed by the mothers contained only 0.05 to 0.1 ppm of fluoride. Kraus12 showed that calcification o f deciduous teeth begins between the twelfth and fourteenth intrauterine week. For these foregoing reasons, the dental caries ex perience of a group of 42 additional Cor vallis children, bom from 1 to 11 months before fluoridation had been initiated, was studied separately. All children in the study had consumed the municipal water since birth and had not been absent from their respective areas for more than two
53 66
53 32
24 28
6
All ages 1)4 132
months in any year. Children who had received topical applications of fluoride or who were taking fluoride by prescrip tion were excluded, as were those children whose parents refused to allow roentgeno grams to be taken. The subjects were solicited by the sen ior author (G .T .) through talks on dental care for the preschool child. These talks were given in all schools of both com munities to members o f the ParentTeachers Association, to parents o f nurs ery school children, to various church groups and broadcast over the radio. The children came from all socioeconomic levels. In spite of all efforts to obtain sub jects, the number of children was lim ited because, by necessity, these small children had to be brought in for exam ination by their mothers on a voluntary basis. The children were examined in late spring or early summer over a period of five years. If, for some reason, a child was no longer available or eligible for the study, an attempt was made to replace him with another subject. N o child was accepted after he had reached five years of age. Therefore, it was not uncommon that many of the children were seen less than five times (Table 1). Oral Examination • Clinical and roent-
TANK— STORV1CK . . . VOLUME 69, DECEMBER 1964 • 79/751
genographic examinations were per formed in the dental office under good auxiliary light. Findings of these exam inations were recorded by the senior author, thereby limiting the variability of diagnosis.13 Chip blowers, mouth mir rors and explorers were used for the clini cal examinations. Oral roentgenograms were taken at each visit: two maxillary and mandibular anterior and four pos terior roentgenograms for the children from two to six years old, and two large inclusive maxillary and mandibular oc clusal roentgenograms for the youngest children. Ultraspeed films were used. The following symbols were used to designate caries experience in deciduous teeth: dmft (decayed, missing and filled teeth; teeth indicated for extraction were included in the designation of missing teeth), dt (decayed teeth), mt (missing teeth), ft (filled teeth) and ds (decayed surfaces). Methods o f observation were identical to those used by Tank and Storvick in a previous study.14 Stages in the progress o f dental caries as described by Massler and Schour15 were modified, and a quantitative dental decay severity
index was devised to measure the extent and depth of decayed surfaces or pulpal involvement based on clinical and roentgenographic examinations. Scores were as follows: 1— Superficial (caries in enamel). 2— Moderate (caries in enamel and su perficial caries in dentin). 3— Moderately severe (enamel under mined). 4— Severe (approaching pulp, enamel collapsed). 5— Pulpitis (caused either by deepseated caries or by trauma without caries). 6— Death of pulp (caused either by deep-seated caries or by trauma without caries). 7— Periapical infection (caused either by deep-seated caries or by trauma with out caries). The number of unerupted, erupted and exfoliated deciduous teeth also were de termined. Statistical Analysis • The means for all variables were calculated as the averages o f the means for each age. These means remove any effect o f age which might
Tab le 2 • Erupted and unexfoliated deciduous teeth per child for children with a fluoride-free water supply (Albany) and a fluoridated w ater supply (Corvallis) Deciduous teeth Girls
Boys
Both sexes
Community
N o. examined
Mean no. of teeth per child
N o. examined
Mean no. of teeth per child
N o. examined
Mean no. of teeth per child
1
Albany Corvallis
17 46
12.2 12.0
19 50
10.3 10.7
36 96
11.2 11.3
2
Albany Corvallis
27 38
17.6 18.0
23 35
18.3 18.1
50 73
17.9 18.1
3
Albany Corvallis
30 32
20.0 20.0
23 34
20.0 19.9
53 66
20.0 20.0
4
Albany Corvallis
29 13
20.0 20.0
24 19
20.0 19.9
53 32
20.0 20.0
5
Albany Corvallis
16 13
19.4 19.5
8 15
19.5 19.3
24 28
19.4 19.4
6
Albany Corvallis
10 16
16.9 18.0
3 11
15.3 17.0
13 27
16.5 17.6
All ages
Albany Corvallis
129 158
17.7 17.9
100 164
17.2 17.5
229 322
17.5 17.7
Age on last birthday
80/752 • THE JO U R N A L OF THE A M E R IC A N DENTAL ASSO C IA TIO N
Table 3 • Decayed, missing and filled deciduous teeth of children with a fluoride-free water supply (Albany) and a fluoridated w ater supply (Corvallis) Age on last birthday Community
1
2
3
4
5
6
All ages
Albany Corvallis
0.14 0.08
1.26 0.59
4.25 1.44
5.51 2.31
6.00 3.29
7.77 3.19
4.16 1.82
Per cent difference
Corvallis
-43
-5 3 *
-66*
-5 8 *
-4 5 *
-59*
-56*
Mean no. of decayed teeth per child
Albany Corvallis
0.14 0.08
1.26 0.59
3.89 1.30
4.96 2.00
4.96 2.00
5.38 1.70
3.43 1.28
Per cent difference
Corvallis
-4 3
-5 3 *
-6 7 *
-6 0 *
-60*
-68*
-6 3 *
Mean no. of missing teeth per child
Albany Corvallis
0 0
0 0
0.09 0
0.06 0
0.17 0
0.31 0
0.10 0
Per cent difference
Corvallis
-100
-1 0 0
-1 0 0
1 o o *
Mean no. of dmft per child
-1 00*
Mean no. of filled teeth per child
Albany Corvallis
0 0
0 0
0.32 0.11
0.68 0.41
1.00 1.32
2.69 1.70
0.78 0.59
0.14 0.09
1.34 0.56
5.08 1.45
7.28 2.66
8.83 2.89
10.92 3.00
5.60 1.78
Per cent difference
Corvallis
Mean no. of decayed surfaces per child
Albany Corvallis
-6 6
-4 0
+32
-3 7
-24
Per cent difference
Corvallis
-3 6
-5 8 *
-7 1 *
-6 3 *
-6 7 *
-7 3 *
-68*
Per cent of children caries-free (without dmft)
Albany Corvallis
89 97
54 79*
11 55*
8 38*
4 39*
0 33*
28 57*
Per cent of teeth caries-free (no dmft)
Albany Corvallis
99 99
93 97
79 93*
72 88
69 83
53 82
78 90*
— = reduction. + = increase. Calculated as follows: Corvallis-Albany Albany ’ Difference significant at the 5 per cent level.
otherwise have been present because the groups of children of different ages were unequal in size. The variation among subjects within an age group was used as an estimate of sampling error. “ F” or “ t” tests were used for all tests of hypotheses to determine statistical sig-
( 100 ).
nificance at the 5 per cent level o f prob ability. These tests were made by Lyle D. Calvin, professor of statistics, Oregon State University. RESU LTS
N o significant differences were found in the posteruptive tooth age of the decidu ous teeth of the subjects, either between the sexes or between the two communi ties (Table 2 ), although the Corvallis children showed a somewhat later ex foliation of their deciduous teeth.
D ecayed , missing and filled deciduous teeth of O regon children with a fluoride-free w ater supply (A lb a n y ) and a flu oridated w ate r supply (C o rv a llis)
Decayed, Missing and Filled Teeth • The dental caries experience in deciduous teeth of the children in Corvallis with its municipal water adjusted to 1.0 ppm o f fluoride and those in Albany with a fluoride-free water supply is shown in Tables 3 and 4 and the illustration. Pronounced reductions in dental caries
TANK— STORVICK . . . VO LUM E 69, DECEMBER 1964 • 81/753
experience occurred for the Corvallis children of all age groups compared with those o f Albany. Dental caries rates were reduced to the extent of 43 per cent at one year of age and 59 per cent at six years o f age for the mean number of dmft per child (Table 3 ). For all ages combined, the reductions were 56 per cent per child. Reductions for the Corvallis subjects were statistically significant for children of all ages except the one-year-old children. Decayed Teeth and Surfaces • Albany
children had a considerably higher num ber of decayed teeth and surfaces than the children of Corvallis (Table 3, 4 ). They had approximately three times as many decayed teeth and surfaces as the children in Corvallis. Caries Severity Index • Through the use of the numerical severity index (Table 6 ), it was found that the depth and ex tent o f the carious surfaces and the ex tent of pulpal involvements for all the Corvallis children, except for those chil dren one year old, were considerably less than for those of Albany. The differences were statistically significant for all groups. The contrast between the communities was especially pronounced for the chil dren from three to six years old and for all age groups combined, with reduction for the Corvallis children ranging from 64 to 76 per cent. Missing Teeth • Albany children had a
mean of 0.10 missing tooth per child (Table 3 ). None of the Albany children had had teeth extracted, and no extrac tions were indicated for children younger than three years of age. From then on, the number increased until at the age of six years 0.31 tooth per child was miss ing. None o f the Corvallis children had any teeth extracted, and no extractions were indicated. • None o f the children of either community had any teeth filled until they were three years old and very few until the age of five (Table 3).
Filled Teeth
Caries-Free Teeth • In Corvallis, 90 and, in Albany, 78 per cent o f the deciduous teeth of children from one to six years old were free from caries attack (Table 3, 4 ). The difference between the com munities was statistically significant. As was to be expected, the percentages of caries-free teeth gradually declined from the age o f one year and were lowest at the age of six years. This decline also was true for the prevalence of children with out past and present caries experience of their deciduous teeth (Table 3, 4 ). At one year of age, 89 per cent of the Albany and 99 per cent of the Corvallis children were caries-free. By the time these chil dren were six years old, none of the A l bany children were caries-free, and only 33 per cent of the Corvallis children were without caries. Differences between the
Table 4 • Decayed, missing and filled deciduous teeth of children one to six years old with a fluoride-free water supply (Albany) and a fluoridated w ater supply (Corvallis)
Mean no. of dmft per child
Boys
Girls
Both sexes
Albany Corvallis
4.31 1.80
3.87 1.78
4.16 1.82
Per cent difference
Corvallis
—58*
i Ch -px •*
Community
-56*
Per cent of teeth caries-free (no dmft)
Albany Corvallis
77 90*
78 90*
78 90*
Per cent of children caries-free (without dmft)
Albany Corvallis
28
27 59*
28 57*
— = reduction. *Difference significant at the 5 per cent level.
55*
82/754 • THEJOURNAL OFTHEAMERICAN DENTALASSOCIATION T a b le 5 • D e c a y e d , m issing a n d filled d e c id u o u s teeth o f ch ild re n o n e to six y e a r s old w ith n o e x p o s u re , w ith p o stn a ta l e x p o s u r e a n d w ith p r e - a n d p o stn a ta l e x p o s u r e to a flu o rid a te d w a te r su p p ly C o n su m p t io n o f flu o rid a t e d w a te r A lb a n y
C o r v a l lis
None
1 t o 11 m onths p o s tn a ta lly
C o r v a llis P re -a n d p o stn a ta lly
N o . o f ch ild re n
114
42
132
N o . o f e xa m in a tio n s
2 29
95
3 22
M e a n no. o f dmft p e r ch ild
4.16
2 .6 5 *
1 .8 2 *
M e a n no. o f dt p e r child
3.43
1 .5 8 *
1 .2 8 *
M e a n no. o f mt p e r child
0.10
0.19
0 .0 *
M e a n no. o f ft p e r child
0.78
0.88
0.59
M e a n no. o f d s p e r ch ild
5.60
2 .2 2 *
Per ce n t o f ch ild re n w ith c a r ie s -fr e e teeth (no dmft)
28
34
1 .7 8 * 57*
♦Difference significant at the 5 per cent level from Albany children.
children of both communities were sta tistically significant from the ages of two to six years and for all ages combined; 28 per cent of the Albany and 57 per cent of the Corvallis children were free from dental caries of their deciduous teeth. POSTN ATAL EXPOSURE TO FLUORIDATED W ATER
The dental caries experience of a sepa rate group of 42 Corvallis children, also one to six years of age, was studied (Ta ble 5). They were bom from 1 to 11 months before fluoridation had been ini tiated, but otherwise they fulfilled all the rigid criteria necessary to be included in the study. This group of children, how ever, was excluded from any of the other investigations included in this report. It was found that those Corvallis chil dren who were born before fluoridation had begun had a higher prevalence of dental caries of the deciduous teeth than those bom after fluoridation. Although the sample of children with only post natal exposure to fluoridated water was small and the difference in caries expe rience was not statistically significant, the
findings were consistent with results of some other investigations.8,11 The children with only postnatal expo sure to fluoridated water showed a lower prevalence of dental caries than those in the fluoride-free control town. The dif ferences in dental caries experience be tween the Albany children and those in Corvallis with only postnatal exposure to fluoridation were statistically significant except for differences in regard to missing and filled teeth. The results, therefore, show that chil dren bom from 1 to 11 months before fluoridation experienced a pronounced reduction in dental caries compared with children in the fluoride-free town of Al bany. Nevertheless, the results of this study indicate that more protection is given to the teeth of those Corvallis chil dren who were exposed to fluoridated water both pre- and postnatally. DISCUSSION
Variation in time of eruption and exfolia tion of deciduous teeth determines the length of exposure of those teeth to the oral environment and thus may affect dental caries experience4 but, in this
TANK—STORVICK . . . VOLUME 69, DECEMBER 1964 • 83/755 study, the differences in eruption and ex foliation time between the two commu nities were insignificant (Table 2). Comparison of dental caries experience with other long-term epidemiologic flu oridation studies could be made only for children from the age of four years because this is the youngest age group for which results have been published.16 Den tal caries activity of the Albany and Cor vallis children was high compared with the caries experience in fluoride-free and fluoridated areas reported elsewhere.2,16-20 This experience was true even when the additional 6 per cent of dmft and 12 per cent of ds found by roentgenographic ex amination were taken into consideration, a method used only in two of the other studies.17,18,20 Two reasons for the high caries r;ates for the Oregon children may be (1) the high susceptibility to dental caries found for children living in western Oregon2,4 and (2) the variability of di agnosis due to different methods and ex aminers.2,13 In spite of the high caries rates, reductions in dental caries experi ence for the Corvallis children of all age groups were significant when compared to those of Albany. Reductions in dental caries activity due to pre- and postnatal exposure to fluoridated water were higher for the four-year-old Corvallis children than for the four-year-old children stud ied by Arnold and co-workers16 in Grand Rapids, Mich. For the five- and six-yearold children, reductions were comparable to those found by Arnold and his co workers16 in Grand Rapids, by Hutton, Linscott and Williams19 in Brantford, Ontario, and by Ast and Chase17 in New burgh, NY. The quantitative dental caries severity index expresses in simple terms the extent and mean number of dental lesions per child, classified by age group and com munity (Table 6). This index or score is based on the results of clinical and roentgenographic examinations, and it reflects the extent, depth and number of carious surfaces and pulpal involvements. In the calculation of this index, data con-
T ab le 6 • Distribution o f the s e v e rity o f d e n ta l c a r ie s (d e c a y e d su rfa ce s) in d e c id u o u s teeth o f ch ild re n with a flu o rid e -fre e w a te r su p p ly (A lb a n y) a n d a flu o rid a te d w a te r s u p p ly (C o rv a llis)
A g e on last b irth d a y
T o ta l s e v e rity in d e x t p e r child A lb a n y
C o r v a llis
Per cent difference, C o r v a llis
1
0.14
0.14
2
2.68
1.38
-4 9 * -6 9 *
00
3
8.49
2.62
4
13.30
4.81
-6 4 *
5
19.29
6.14
-6 8 *
6
24.85
5.85
-7 6 *
All a g e s
11.46
3.54
-6 9 *
— = reduction. *Difference significant at the 5 per cent level. fN um ber of decayed surfaces X severity index number.
ceming filled surfaces as well as the de cayed surfaces represented by extracted teeth were not included because a filling may have extended into tooth surfaces which had not been decayed and because the number and extent of carious lesions in an extracted tooth were not known. It was shown that the difference in dental caries severity index between age groups was considerable and, for the Albany subjects, the increase in extent and num ber of decayed surfaces and untreated pulpal involvements per child was sta tistically significant for all ages, except for the one-year-old children when com pared with those of Corvallis. Savara and Suher21 studied the caries experience of children in Portland, Ore, where the water supply is not fluoridated. They found fewer children caries-free at the age of one year than were found in the present study, but they reported a con siderably higher percentage of caries-free children from the ages of two to six years than was found in Albany. This higher percentage was also found in various prefluoridation studies on children rang ing in age from two to five,1 five to six2 and six to eight years.20 In some of the postfluoridation reports,2,20 however, the percentage of children in comparable age
84/756 • THEJOURNAL OF THEAMERICAN DENTALASSOCIATION groups without past or present dental caries of their deciduous teeth was similar to that found in Corvallis in the present study. It was shown previously2 that the fluo ride ion has some caries-inhibitory effect on deciduous teeth, even when incorpo rated into the tooth structure either before eruption during the period of calcifica tion or after eruption. This caries-inhibi tory effect of the fluoride ion again was demonstrated in the present study. The even greater benefit of pre- and postnatal exposure to fluoridated water on the de ciduous teeth of children from the age of four years, found by a number of other investigators,2,8’14,20 again was substan tiated in this report. It also has been shown in the present study that children from the ages of one to three years also derive considerable benefits. Carlos, Gittelsohn and Haddon22 did not find any significant relation between ingestion of fluoridated water by gravid women and prevalence of dental caries in deciduous teeth of their offspring at the age of six years, whereas Feltman and Kosel8 presented evidence that fluoride ingested during the first and second tri mester of pregnancy passed the pla cental barrier, entered the fetal blood supply and consequently increased the resistance to dental caries of the decidu ous teeth of children ranging in age from 3 to 12 years. This, reduction in caries of deciduous teeth due to prenatal expo sure to fluoridated water in addition to postnatal consumption of it, when com pared with the effect of postnatal con sumption alone, was also consistent with the results of the present study. SU M M ARY AND CON CLUSION S
The effect of pre- and postnatal exposure to water from a supply adjusted to 1.0 ppm of fluoride on the dental caries ex perience in deciduous teeth of children from the ages of one to six years was in vestigated in a semi-longitudinal study. The dental caries experience in a separate
group of children who consumed fluori dated water from 1 to 11 months after birth also was determined. The following results were obtained: 1. Dental caries rates of the children were significantly reduced by pre- and postnatal exposure to fluoridated water when compared with the caries rates of the children whose water was fluoridefree. 2. Children with only postnatal expo sure to fluoridated water showed pro nounced reductions in dental caries rates when compared with the dental caries rates of children of the control town, but the reductions were less than those found for the children with pre- and postnatal exposure to a fluoridated water supply. This paper is the first in a series of articles on dental caries experience of O regon children one to six years of age in Corvallis with a fluoridated water supply and in Albany, where the water is fluoride-free. Two a d d i tional papers will be published in subsequent issues of T H E JO U R N A L . *Associate professor of nutrition research, nutrition research laboratory, School of Hom e Economics, O regon State University, Corvallis. tProfessor of foods and nutrition, nutrition research laboratory, School of Hom e Economics, O regon State University, Corvallis. 1. Finn, S. B. Second annual progress report on fluo ride investigations. New York D. J. 13:78 Feb. 1947. 2. Tank, G., and Storvick, C. A . Dental caries expe rience of school children in Corvallis^ Oregon, after 7 years of fluoridation of water. J. Pedlat. 58:528 April 1961. 3. Storvick, C . A., and Sullivan, J. H. Total hardness and fluoride content of O regon public water supplies. J. Am. W ater W orks Assoc. 42:589 June 1950. 4. Tank, G:, and olhers. Cooperative nutritional status studies in the western region. III. Variation in dental caries experience am ong children of five western states. Oregon State College, A g. Exp. Sta. Tech. Bui. 45:15, 1959. 5. Ericsson, Y., and Malmnas, C. L. Placental transfer of fluorine investigated with F18 in man and rabbit. Acta Obstet. Gynec. Scandinav. 41:144, 1962. 6. Gardner, D. E., and others. Fluoride content of placental tissue as related to fluoride content of drink ing water. Science 115:208 Feb. 22, 1952. 7. Held, H. R. Fluormedikation und Blutfluor. Schweiz, med. Wchnschr. 84:251 Feb. 20, 1954. 8. Feltman, Reuben, and Kosel, George. Prenatal and postnatal ingestion of fluorides— fourteen years of inves tigation— finaI report. J. D. M ed. 16:190 Oct. 1961. 9. Ziegler, E. Untersuchungen uber die Fluorierung der Milcn zur Cariesprophylaxe. Mitt. Naturwiss. Gesellsch. Winterthur 28:1, 1956. 10.^ Gedalia, I., and others. Placental transfer of fluorine in the human fetus. Proc. Soc. Exper. Biol. Med. 106:147 Jan. I96J. . II. Gedalia, I., and others. Fluoride content of teeth and bones of human foetuses. Arch. O ral Biol. 9:331 May-June 1964. 12. Kraus, B. S. Calcification of the human deciduous teeth. J A D A 59:1128 Dec. 1959. 13. Berggren, H., and Welander, Erik. Unreliability of caries recording methods. Acta Odont. Scandinav. 18:409 Dec. I960.
TANK—STORVICK . . . VOLUME 69, DECEMBER 1964 • 85/757 14. Tank, Gertrude, and Storvick, Clara A. Effect of naturally occurring selenium and vanadium on dental caries. J. D. Res. 39:473 May-June I960. 15. Massler, Maury, and Schour, Isaac. Atlas of the mouth and adjacent parts in health and disease. C hi cago, Am erican Dental Association, 1952, plate 9. 16. Arnold, F. A., Jr., and others. Effect of fluoridated public water supplies on dental caries prevalence. Pub. Health Rep. 71:652 July 1956. 17. Ast, D. B., and Chase, H. C. Newburgh-Kingston caries fluorine study. IV. Dental findings after six years or water fluoridation. Oral Surg., Oral M ed. & Oral Path. 6:114 Jan. 1953. 18. Ast, D. B.t and others. Newburgh-Kingston cariesfluorine study. XIV. Com bined clinical and roentgeno-
graphic dental findings after ten years of fluoride expe rience. J A D A 52:314 March 1956. 19. Hutton, W. L., Linscott, B. W., and Williams, D. B. Final report of local studies on water fluoridation in Brantford. Canad. J. Pub. Health 47:89 March 1956. 20. Hill, I. N., Blayney, J. R., and Wolf, W. Evanston dental caries study. XVI. Reduction in dental caries attack rates in children six to eight years old. J A D A 53:327 Sept. 1956. 21. Savara, B. S. and Suher, Theodore. Incidence.of dental caries in children I to 6 years of age. J. D. Res. 33:808 -Dec. 1954. 22. Carlos, J. P., Gittelsohn, A. M., and Haddon, W., Jr. Caries in deciduous teeth in relation to maternal ingestion of fluoride. Pub. Health Rep. 77:658 Aug. 1962.
Imagination and the Scientist • I n o rd e r to be u se fu l in science, im a g in a tio n m u st be co m b in e d w ith a keen sense fo r w h a t is im p o rta n t. T h i s assessm ent m ust, of necessity, be m a d e in stin c tiv e ly o n insufficient evide n ce at a tim e w h e n im p o rta n c e is n o t yet d e m o nstrab le . H e re , p e rh a p s m o re t h a n i n a n y o th e r respect, th e scientist m u st d e p e n d o n in n a te gifts. I t is v ir t u a lly im p o ssib le to teach im a g in a tio n . O n ly o u r v is io n fo r the im p o rta n c e o f t h in g s can be sh a rp e n e d t h ro u g h experience, b y tria l a n d error. T h i s d ep endence o f critica l ju d g m e n t u p o n expe rie nce e x p la in s w h y, i n the cou rse o f life, it takes so m u c h lo n g e r to d e v e lo p a sense o f v a lu e s t h a n to e x h ib it the la rg e ly in n a te p o w e r o f im a g in a tio n . T h e fla ir fo r the p o te n tia l p ra c tic a l o r theoretical im p o rta n c e of the t h in g s th a t w e im a g in e is n o t itse lf im a g in a tio n ; it is m e re ly a p re re q u isite fo r the selection, a m o n g in n u m e r a b le im a g in a ry pictures, o f those h a v in g sign ific a n t a p p lic a tio n s in reality. T h e c o m b in e d ac tiv ity o f first im a g in in g a n d then fix in g the im p o r ta n t aspects o f the im a g in e d p ic tu re o n to co n scio u s re a lity is th e ba sis o f creative t h o u g h t — the m o st e le v a tin g a n d sa tisfyin g a c tiv ity o f w h ic h the h u m a n m in d is capable. T h e act of scientific a n d artistic creation, m u c h lik e th a t of pro cre atio n , giv e s th e e n joym e n t o f release fr o m th e te n sio n s o f a ne e d— a h u n g e r — w h ich , w h e n appeased, leaves o u r w h o le b e in g d e lig h t fu lly flagge d b y th e sense o f fu lfillm e nt. Hans Selye, From Dream to Discovery, New York, M cG raw-H ill Book Co*, Inc., 1964, p. 44; 45.