Dental Caries (DMF) Experience in Relocated Children Exposed to Water Containing Fluorine. II

DENTAL CARIES (DMF) EXPERIENCE IN RELOCATED CHILDREN EXPOSED TO WATER CONTAINING FLUORINE. II Henry K l e in * D .D .S ., S c.D ., Bethesda, M d .

*Dental O fficer, Division of Public Health Methods, U . S. Public Health Service.

val consumed water containing fluorine to the extent of 3 parts per million. In a preceding report,1 it was shown that new caries attack in the two-year interval from 1943 to 1945 among chil­ dren who were 8-10 years old in 1943 was approximately 60 per cent lower in the fluoride area than in the control area. Children of those ages were pro­ tected more in the subsequent two-year interval than were children who were 12-14 years of age at the beginning of exposure. From this finding, the con­ clusion was derived that, among all caries-free teeth present in the mouth when exposure to fluorine is begun, the more recent the eruption the greater is the protection against caries. It is the purpose of the present report to examine the effect of the presence of trace amounts of fluorine in drinking water on the incidence of new caries in those individual teeth which have the. highest caries susceptibility, namely, the first and second molars and the second bicuspids,2 and to differentiate between the caries-inhibiting effect of such waters on teeth (a) when already present in the mouth at the beginning of exposure and (b) not present in the mouth at the

fT h e first examination findings in 1943 were made in the control locality by S. T. Ichiyasu and in the fluoride locality by T . T. Oku no. A ll the second examinations in 1945 were made by Toyohara Shimizu, Dental Officer, O ffice of Indian Affairs. The water samples were analyzed by Elias Elvove, Senior Chemist, U . S. Public Health Service. The kind assistance of Ralph B. Snavely, Medical Director, and .Oskar Mickelsen, Dental D i­ rector, O ffice of Indian Affairs, is also acknowledged.

1. Klein, Henry: Dental Caries Experience in Relocated Children Exposed to Drinking Water Containing Fluorine. I. Incidence of New Caries After Tw o Years of Exposure Among Previously Caries-Free Permanent Teeth. Pub. Health Rep. 6 0 :1462, December 7, J9452. Klein, Henry, and Palmer, C. E .: Studies on Dental Caries. X II. Comparison of the Caries Susceptibility o f the Various Morpho­ logical Types of Permanent Teeth. J. D. Res. 20:203, June 1941.

Purpose of Study T h e following study compares the amount of new caries developing in per­ manent teeth present in the mouth at the beginning o f exposure to water contain- • ing fluorine with the amount of new ca­ ries developing in permanent teeth erupt­ ing during the period of exposure. It is based on seriatim dental examinations of 316 children o f Japanese ancestry trans­ ferred late in 1942 from their homes in the- city of Los Angeles and environs to W ar Relocation Centers in California and Arizona. T he examinations were made with the aid of dental mirrors and explorers in the early summer of 1943, approxim ately six months after the ar­ rival of the children at the Centers, and again two years later, in the early sum­ mer of 19 454 The 196 boys and girls residing at the California Center from 1943 to 1945 consumed w ater containing only o. 1 part per million o f fluorine (a value within the error o f determination). In con­ trast, the 120 children residing at the Arizona Cen ter over the same time inter­

Jour. A .D .A ., V ol. 33, September 1, 1946

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AGE ( Y E A R S ) IN 1943 Fig. 7.— In the summer of 1943: Relation between age and number of caries-free perma­ nent first molars per one hundred children of both sexes in the fluoride and control areas.

beginning but erupting into the mouth during that exposure. Findings Permanent First Molars.— A t the first examination in M ay 1943, the two .groups of children— -those residing in the fluoride area and those living in the con­ trol area— differed only slightly with regard to caries experience. T h e chil­ dren in the fluoride area averaged 2.5 caries-free first molars; those in the con­

trol area, 2.8 (Table 1 and Fig. 1). Am ong children 8-10 years old in 1943 who had resided in the fluoride area for the next two years, 36 per cent of the first molars caries-free in 1943 had been at­ tacked by 1945, as compared with 58 per cent in the area with fluoride-free water (Table 2 and Fig. 2). Am ong permanent first molars caries-free in 1943, the percentage difference in caries incidence during the next two years in the group exposed to fluorine, as con-

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T a b l e 1 . - « E r u p t e d P e r m a n e n t F i r s t M o la r s , 1 9 4 3 ; A v e r a g e R u n t e r o f C a r i e s - F r e e F i r s t M o la r s Among 3 1 6 C h i l d r e n A r r a n g e d b y A g e , S e x a n d T y p e o f W a te r C on su m ed Age In W a te r *

8 0

10

1943

»

N umber o f

(Y ea rs) 12

10

14

AM

C h ild r e n

B oys

F lu o r id e grou p C o n tr o l group

14 4

17 10

21 4

12 10

12 ,8

12 6

7 10

G ir ls

F lu o r id e grou p C o n t r o l G rou p

17 7

15 9

14 10

9 7

20 13

13 13

13 101 » 68

B o th

F lu o r id e grou p C o n tr o l grou p

31 11

32 19

35 14

21 17

32 21

25 19

20 196 19 120

95 52

N um ber o f C a H e s - F r e e F i r s t M o la r s P e r C h i l d B oys

F lu o r id e group C o n tr o l group

2 .1 3 .0

2 .6 3 .3

2 .6 3 .5

3 .1 2 .8

2 .7 3 .1

2 .7 2 .0

2 .6 3 .4

2. 6f 3 . Of

Gl r l s

F lu o r id e grou p 2 .7 2 .0 C o n tr o l grou p

3 .0 3 .3

2 .2 2 .6

1 .2 2 .3

2 .5 3 .2

2 .3 1 .8

2 .7 2 .4

2 .4 f 2 .5 f

B o th )

F lu o r id e grou p C o n tr o l grou p

2 .4 2 .5

2 .8 3 .3

2 .4 3 .1

2 .2 2 .6

2 .6 3 .2

2 .5 1 .9

2 .6 2 .9

2 .5 2 .8

* T he w a t e r a t t h e A r i z o n a C e n t e r c o n t a i n e d 3 p . p f l u o r i n e ; t h a t a t t h e C a l i f o r n i a C e n t e r w as f l u f r e e (b a se d on s i n g l e s a m p le s ) , f S la p le a r ith m e tic a v e r a g e o f s e v e n a g e - s p e c if ic ra t e s . | S i m p le a r i t h m e t i c a v e r a g e o f t h e s e x - s p e c l f l c r fo r ea ch g ro u p .

trasted with the group using fluoridefree water, is greatest for children of the younger ages. Hence, among the chil­ dren of both sexes who were 8-10 years old in 1943, those in the fluoride area developed only two-thirds as much new molar caries from 1943 to 1945 as did the control group, but, for children who were 12-14 years of age in 1943, no sig­ nificant difference in caries incidence occurred for this tooth. These findings indicate that first m o­ lars already present in the mouth of young children when fluorine exposure is begun obtain considerable protection against new caries. T h e recently erupted molars receive more protection than do first molars which have been in the mouth for longer periods. Permanent Second Molars.— T able 3 shows the number of caries-free second molars present in the mouth at first ex­ amination and the number and percent­ age which showed evidence of caries at­ tack two years later. For this tooth, data on children 12, 13 and 14 /ears old are available. T h e children of these ages of both sexes in the fluoride area had only

16 per cent of their previously cariesfree second molars attacked by thé sum­ mer of 1945, while those in the control area had 47 per cent attacked— a sig­ nificant inhibition in the fluoride area. Information on the number of second molars erupting into the mouth of chil­ dren 12-14 years old in the two areas during the two-year exposure and the number and percentage which had been attacked by caries by the end of the ex­ posure interval is also given in Table 3. Am ong children of both sexes in the fluoride area, about 4 per cent of the sec­ ond molars erupting in the exposure in­ terval were attacked by caries, whereas 26 per cent of such teeth showed evi­ dence of caries attack by 1945 among children in the control area. From these data it m ay be concluded that second molars exposed to fluorine during the latter part of their calcification in the jaw before eruption or during the proc-

T a b le 2 . — E r u p te d P er m a n en t F l .r s t M o la r s , 1 9 4 3 - 1 9 4 0 ; Number C a r i e s - F r e e i n 1 9 4 3 a n d Number an d P e r C e n t S h ow in g E v id e n c e o f C a r le s A t t a c k (DMF) b y 1 9 4 5 , Among 3 1 6 C h ild r e n A r r a n g e d b y A g e , S e x an d Type o f W ater C on su a ed Age i n

8 1

9

1949

(Y e a r s)

1 1 0 |s-10 1 1 1 11 2 1 13 1 14

{1 2 - 1 4

Number o f C a r i e s - F r e e F i r s t M o la r s in 1943 B oys

r i d e gro u p r o l g r ou p

F lu o r id e grou p Cl r l s C o n t r o l g rou p B o th

F l u o r i d e gro u p C o n t r o l g ro u p

10? 158 Number o f new DMF F i r s t M o la r s by 1945

B oys

F lu o r id e group C o n t r o l g ro u p

F lu o r id e grou p G i r l s C o n t r o l g rou p B o th

F lu o r i d e grou p C o n tr o l grou p P er C e n t o f New DMF F i r s t M o la r s b y 1 9 4 5 Among F i r s t M o la rs C a r l e s - F r e e i n 1943

B oys

F lu o r id e g ro u p 36.7 31.1 4 3 .6 3 7 .I f 35 .1 4 0 .6 18 .8 50 .0 3 6 .5f C o n tr o l g ro u p 58 .3 83.6 4 2 .9 5 4 .9f 60 .7 16 .0 25 .0 5 0 .0 3 0 .3f

F l u o r i d e g r ou p 28 .3 ♦0.0 35 .5 3 4 .6 | 2 7 .3 nft.o 2 0 .0 4 2 .9 3 3 .6f G i r l s C o n tr o l g ro u p 64.3 66.7 53 .8 6 1 .6 1 5 0 .0 46 .3 5 0 .0 4 0 .9 4 5 .7f F lu o r id e g rou p 32.5 35.6 3 9 .6 3 5 .9 B o th J C o n t r o l grou p 61.3 65.2 48 .4 5 8 .3

3 1 .2 39 .3 19.4 4 6 .5 35 .1 55 .4 31 .2 37.6 4 5 .5 38.1

* The w a te r a t t h e A r iz o n a C e n t e r c o n t a i n e d 3 p .p .m .- f l u o ­ r i n e ; t h a t a t th e C a l i f o r n i a C e n t e r w as f l u o r i n e - f r e e (b a s e d on s i n g l e s a m p l e s ) , t S im p le a r i t h m e t i c a v e r a g e o f a p p r o p r i a t e t h r e e a g e - s p e c l f lc p e r c e n ta g e s, t S im p le a r i t h m e t i c a v e r a g e o f t h e s e x - s p e c l f l c p e r c e n t a g e s fo r e a c h a g e g r o u p .

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8-10

12-14

AGE ( Y E A R S ) IN 1943 Fig. 2.— In the summer of 1945: Relationship between age in 1943 and percentage of new D M F permanent first molars among first molars caries-free in 1943 for children of both sexes in the fluoride and control areas.

css of eruption into the mouth are pro­ tected more against caries attack than are second molars exposed to fluorine after eruption. Permanent Second Bicuspids.— Table 4 provides data for children 12, 13 and 14 years old on the percentage of cariesfree second bicuspids in the mouth in 1943 which were attacked by caries in the subsequent two-year interval. The incidence of new caries in second bicus­ pids among children of both sexes ex­

posed to fluorine is approximately 7 per cent, as contrasted with 10 per cent for the control area, a difference which is of border-line significance. Information on the number of second bicuspids erupting into the mouth dur­ ing the two-year interval in both groups of children and the percentage of these attacked by caries is given in Table 4. Obviously, among children of the flu­ orine area, these teeth were exposed to fluorine before or during the process of

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Table 3.-— P e r m a n e n t S e c o n d Mol'ars, Erupted or Un e r u p t e d In 1943: N u m b e r and T e r C e n t A t t a c k e d by Carles (DMF) by 1915, Am o n g 136 C h i l d r e n 12-14 Years o f Age Arranged b y Sex and Type o f Hater Consumed E r u p t e d Second Molars In 1943 Sox

Un c ruptcd Second Molars In l»4!i

Wat e r * A«e

(Years)

Age

(Years)

1»

13

14

All

IU

13

-14

All

Fluoride group Control group

3 4

S3 12

15 12

41 28

22 10

22 15

12 17

56 42

H u o r l d e gr o u p Girls C o n t r o l gro u p

8 3

4 IS

44 22

56 40

41 27

36 30

8 8

85 65

Roys

Nu m b e r o f Ne D M F S e c o n d Mol by 1946

Number of NEH DM F S e c o n d Molars b y 1945

F l u o r i d e gr o u p C o n trol g r o u p

0 3

4 4

7 10

0 1

0 3

1 6

1 10

Fl u o r i d e gr o u p Girls C o n t r o l gr o u p

1 1

1 8

11 23

4 6

1 14

0 2

' 5 21

Hoys

14

P e r C e n t o f New D M F S e c o n d Molars b y 1 9 4 5 Among S e c o n d Molars Ca r i e s - F r e e in 1943 Roys

Per Cent of Ke« D M F S e c o n d Molars by 1945 Among Se cond Molars Un e r upted In 1943

Fluoride group 0.0 17.4 20.0 10.51 0.0 0.0 8.3 2.81 Co n t r o l gro u p 75.0 33.3 25.0 »4.4j 10. Û 20.0 35.3 21.81

F l u o r i d e g r o u p 12.5 26.0 20.5 19.3f 9.8 2.8 0.0 4 .21 Clrls C o n t r o l gr o u p 33.3 63.3 63.6 50.11 18.5 46.7 25.0 30. If Roth* F l u o r i d e gr o u p 6.3 21.2 20.3 15.9 4.9 1.4 4.2 3.5 Co n t r o l group 6 4 . 2 43.3 44.3 »7.3 14.3 33.3 30.2 26.0 • T h e w a t e r at the A r i z o n a C e n t e r c o n tained 9 p.p.«. f l u o ­ rine; that at the C a l i f o r n i a C e nter «as f l u o rine-free (based on s i n g l e samples), t S i m p l e a r i t h m e t i c a v e r a g e of approp r i a t e three agesp e c i f i c p e r c e n t a g e s . J S i m p l e a r i t h m e t i c a v e r a g e of the s e x - s peclflc p e r c e n t ­ ag e s for each age group.

Ta b l e 4 . — Pe r m a n e n t S e c o n d Bicuspids, Er u p t e d or Unerupted In 1943; Num b e r a n d P e r C e n t Atta c k e d by Carles (DMF) by 1945, Am o n g 136 C h i l d ren 12-14 Years o f Age Ar r a n g e d By Sex and T y pe o f Water Cons u m e d Sex

Water*

Age

(Years)

»

,4

Age All

N u m b e r o f Second Blc usplds C ariesFree 1n 1943

12

(Years)

.3

.4

All

Number 0f Second Bicuspids Unerupted in 1943

Fl u o r i d e gr o u p C o n t r o l gr o u p

21 9

27 15

14 31

62 55

26 23

18 8

14 7

48 98

F l u o r i d e gr o u p Girls C o n trol gr o u p

26 16

37 39

40 27

103 82

53 33

13 13

8 1

74 47

Hoys

Number of Ne* DMF S e cond Bleu spi ds by 1945

Number o f Ne» D MF Second B 1 cuspids by 1945

i l u o r i d e group C o n t r o l group

2 0

2 1

1 3

5 4

1 3

0 0

0 0

1 3

Fl u o r i d e group Girls C o n trol group

2 1

0 9

3 3

5 13

0 2

0 1

t> 0

0 3

Boys

Per Cent o f N ev D MF S e c o n d 81 c u s p i d s by 1946 Am o n g S e cond Blc u s p l d s C arlesFree in 1943 Boys

F l u o r i d e gr o u p 9 . 6 C o n t r o l group 0 .0

7.4 6.7

7.1 9.7

Per Cent of New DVF S e c o n d B i c u spids by I945 Among S e cond B i c u spids Unertipted In 1943

8 . Of 3.8 5.&t 13.0

0.0 0 .0

0.0 0. 0

1.31

F l u o r i d e g r o u p 7.7 0.0 7.5 Clrls C o n t r o l gr o u p 6.3 23.1 11.1

5.11 0 .0 3.5f 6.1

0.0 7.7

0.0 0.0

o.o 1 4.61

F l u o r i d e g r o u p 8.7 3.7 7.3 Both* C o n trol group 3.2 14.9 10.4

6.6 9.6

0.0 3.9

0.0 0 .0

0.7 4.5

1.9 9 .6

* T h e wat e r at the A r i z o n a Center contained 3 p.p.». fluo­ rine! that at the C a l i f o r n i a Center « as fluorine-free (based on s i n g l e sample«), f S i m p l e a r i t h m e t i c a v e r a g e o f approp r i a t e three agespeclflc percentages, t S i m p l e a r i t h m e t i c a v e r a g e of the sex - s p e c l f l c p e r c e n t ­ ages for e a c h a g e group.

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eruption. T h e findings for this tooth suggest that such exposure m ay provide a larger measure of protection against caries attack than is provided by ex­ posure some time after eruption has been completed. Discussion T h e fluorine hypothesis in dental ca­ ries research has received considerable attention recently. Stated briefly,3 it pro­ poses that an inverse relation exists be­ tween dental caries susceptibility and the ingestion of trace amounts of fluorine. It has been suggested4, 5 that fluorides be added to community water supplies— and such fluorination is now being done in at least two fairly large cities— with the aim of determining whether addi­ tions of fluoride to the drinking water consumed by a population not previously so exposed will inhibit new caries attack without toxic effects. Arnold6 has reported that fluorides ex­ ert their effect on reducing caries inci­ dence only when taken in the diet while the teeth are developing in the jaw , and that little beneficial influence in that di­ rection can be expected in persons who are more than 5 or 6 years of age at the time that fluorine ingestion is begun. O n the other hand, other experience, par-' ticularly with topical application of flu­ orine solutions, suggests that teeth already erupted in the mouth m ay be protected against caries attack even though they 3. Klein, Henry, and Palmer, C . E .: Dental Caries in American Indian Children. Public Health Bulletin 239. Washington: U . S. Government Printing Office, 1937. 4. Ast, D. B .: Caries-Fluorine Hypothesis and Suggested Study to Test Its Applicatipn. Pub. Health Rep. 58:857, June 4, 1943. 5. Dean, H. T . : O n the Epidemiology of Fluorine and Dental Caries. Fluorine in Dental Public H ealth: Symposium. New Y ork: New York Institute of Clinical Oral Pathology, 1944. 6. Arnold, F. A . : Discussion of the Possi­ bility of Reducing Dental Caries by Increas­ ing Fluorine Ingestion. J. Am. Col. Den. 12 :6 1, 1944.

Schlack

e t a l .—

Sta tu s

are not exposed to fluorine during pre­ em ptive development.7"9 T h e findings of W eaver10 are in agreement with this latter view, although he concludes that “ the evidence obtained is on the whole in fa,vor of the view that the influence of F is exerted on the teeth during the pre­ emptive period.” The observations recorded in the pres­ ent report further support the fluorine hypothesis. T h e findings provide what 7. Bibby, B. G .: Effects of Topical Appli­ cation of Fluorides on Dental Caries. Fluorine in Dental Public H ealth: Symposium. New York: New York Institute of Clinical Oral Pathology, 1944. 8. Cheyne, V . D . : Human Dental Caries and Topically Applied Fluorine. J.A.D.A. 29:804, M ay 1, 1942. 9. Knutson, J. W ., and Armstrong, W . D .: Effect of T opically Applied Sodium Fluoride on Dental Caries Experience. Pub. Health Rep. 58 :170 1, November 19, 1943. 10. Weaver, R .: Fluorine and Dental C a ­ ries; Further Investigations on Tyneside and in Sunderland. Brit. D. J. 7 7 : 185, October 6, 1944.

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may be considered a “ pilot study” of some of the results in caries inhibition to be expected from fluprination of wa­ ters in communities previously not so exposed. O f particular interest is the finding that first and second molars and second bicuspids already erupted in the mouth are protected significantly against caries attack provided they become ex­ posed to the fluorine-bearing waters within a short time after eruption. T he data on erupting second molars and second bicuspids, although few in number, suggest that teeth which go through the process of eruption during exposure to fluoride waters receive most protection against caries attack. This observation may be interpreted to indi­ cate that the protective effect of fluorine is most marked if the tooth is exposed to this chemical either before eruption or during the time interval covered by the process of eruption of the tooth into the mouth.— U . S. Public Health Serv­ ice.

DENTAL STATUS OF 71,015 NAVAL PERSONNEL AT FIRST EXAMINATION IN 1942 C. A . Schlack * D .D .S .; J. S. R estarski* D .D .S ., M .D .S .; and. E . F . D ochterm an, f M .S ., Bethesda, M d . W ith the initiation of duplicate dental records in the Navy, a source of consider­ able material for statistical evaluation became available at the Bureau of M edi­ cine and Surgery. In 1942 Capt. A. K nox,1 then chief of the Dental Division.

suggested that a study be undertaken to evaluate the dental status of a large num­ ber of naval personnel entering the serv­ ice. in order to make a more accurate analysis of dental needs and to make known those problems in treatment con­ fronting the Navy Dental Corps. O ther studies on the dental status of several different populations and employ­ ing various numbers of persons have been

*Commander (D C ) USN. fLieutenant (jg ) , H (W ), U SN R . From the Naval M edical Research Institute, National Naval M edical Center. The opinions and views set forth in this article are those of the writers and are not to 2. Hollander, F., and Dunning, J. M .: be considered as reflecting the policies of the Study by Age and Sex of the Incidence of Den­ Navy Department. 1. Knox, A .: Personal communication to tal Caries in O ver 12,000 Persons. J. D. Res. 18:43, February 1939. C. A. Schlack in 1942. Jour. A.D .A., Vol. 33, September 1, 1946