DOCTORAL DISSERTATION SERIES

TITLE

CariesInR 5,
AUTHOR

U'JLj
DEGREE

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PUBLICATION NO.
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M

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UNIVERSITY MICROFILMS
A N N ARBOR

-

MICHIGAN

THE INFLUENCE OF CERTAIN
DIETARY FACTORS ON THE PRODUCTION OF DENTAL
CARIES IN A SUSCEPTIBLE STRAIN OF RATS

by
Kenneth Jean Olson

A THESIS
Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
in partial fulfillment of the requirements
for the degree of
DOCTOR OF PHILOSOPHY

Department of Chemistry
191*7

TABLE OF CONTENTS
Page
Introduction............................
1
General Historical,
...................
k
The Relation of Fluorides to Dental Caries.......... 10
Historical...
......10
Experimental...........
12
Part I - Effect of Continuous Fluoride Feeding. 13
Part II- Prenatal Effects of Fluorides......... 16
Part III-Lactation and Postweaning Effects of
Fluorides...............
16
Part IV- Postweaning Effects of Fluorides
18
Discussion of Fluoride Results................. 20
2k
Schematic Chart...................
Conclusions........
25
The Relation of Carbohydrates to Tooth Decay....... 26
Historical............................
26
Part I - A Study of the Effect of Diets Contain­
ing Finely Ground Rice, Sucrose, and
no Fermentable Carbohydrates on the
Production of Dental Caries........... 28
Part II- The Influence of Rice on the Caries
Producing Effects of Sucrose.......... 33
Discussion. .................
3k
Conclusions
..........
37
The Influence of Powdered Whole Milk, Evaporated
Milk, and Evaporated Milk plus Sucrose on the
Production of Dental Caries
......
38
Discussion......
UO
Conclusions
..............
1*2

ACKNOWLEDGEMENT

The author wishes to express his sincere appre­
ciation and gratitude to Doctor Carl A. Hoppert,
Professor of Chemistry, for his guidance, coopera­
tion and friendship.
•j h h h h h h h h b ;-

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Dedicated to
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INTRODUCTION

It has long been recognized that tooth decay is perhaps
the most common disease of mankind.

The history of dentistry

reveals that the study of its cause and prevention is of long
standing, however, progress in the direction of caries preven­
tion has been somewhat more evident during the past 2j? years.
It has been demonstrated by workers in several fields that
dental caries is influenced by a variety of factors of which
the most prominent are the bacteriological and the nutritional.
However, a more thorough study of caries reveals other factors
of which the more important are the physical nature of the
diet and heredity.
Each of these four fields has a definite bearing on the
content of this

thesis, the

heredity, indirectly.

first three directly and the last,

It will be of interest to elaborate

further on the matter of heredity. An extensive study carried
out by Hunt, Hoppert, and Erwin (1) on the inheritance of caries
susceptibility in albino rats resulted in the production of a
strain of animals well suited for dental caries investigation.
At this writing the susceptible colony is composed of rats
in the 16th generation of selective breeding and shows remark­
able homozygosity regarding caries of the lower molars.
The cariogenie ration developed by Hoppert, Webber and
Canniff (2) was used throughout the inheritance study of Hunt

and his associates.

This ration was composed of the following

constituents:
Coarsely ground hulled rice
Whole milk powder........
Alfalfa leaf meal........
Sodium chloride..........

66%
30%
3%
1.%

It was first observed by Hoppert and co-workers (2) that
the particle size of the ground rice was important in initiat­
ing caries.

The rice used in the above ration was ground in

such a manner that approximately 10% was retained by a 20 mesh
screen (1*00 holes per square inch).

The 9th generation

animals showed caries at a mean age of 61*.6 -A .7 days when
exposed to this ration at the

age of 35 days.

For nutritional

studies on caries prevention, however, this ration was found
too drastically cariogenie and caused extensive fracturing.
Short term experiments revealed that finely ground rice length­
ened the caries time and made for a more typical tooth decay.
The above ration containing rice ground to retain 2.% on a 20
mesh screen will initiate caries in 35 to 70 days with slight
variations in the susceptible strain of animals.
tion will be referred to as the

This modifica­

caries producing fine rice ration

throughout this thesis and was used as the. control diet.

This

ration is remarkably consistent in producing caries but allows a
greater fluctuation between families in initiating time than the
coarser rice diets.
by

This may be experimentally compensated for

comparing litter mates within a given family.
-2-

Under these

conditions animals are rarely found to deviate from their litter
mates by more than one week*

Variations of two weeks or less

are considered insignificant throughout this thesis.
All carious lesions recorded in this work are macroscopic
in nature and were observed biweekly in the living animal* An
original record of caries initiation and progression was kept
by scoring a tooth map and accompanying a particular entry with
the date of observation* A positive lesion was recorded as n4n
while one in doubt was marked "?".
nated as doubtful

The last observation desig­

was taken as the date of caries initiation*

Plate I illustrates the extent of such a lesion.
III represent moderate and

Plates II and

severe caries respectively.

This

method allows the observation of differences in caries progres­
sion as well as initiation.

No effort was made to compare the

relative number of carious lesions as the progression is so
rapid that several small ones terminate in one large involvement
in a short period of time.
When studying the tabulated data in some cases blanks
appear under the 11initial” and”moderate” stages*
first case means this
were begun*

stage was reached before observations

In cases of “moderate” blanks the animal progress­

ed from the initial to the severe
readings.

A blank in the

stage between two successive

PLATE I

Initial Caries

[fpW'’

PLATE IX

PLATE III

Csz'i.^s

Severe Caries

Plates I, II, and III, represent the approximate
degree of caries referred to as initial, moderate,
and severe respectively.

GENERAL HISTORICAL

The history of dental caries in rats dates back to 1922
when McCollum, Simmons, Kinney and Grieves (3) recorded posi­
tive findings in the albino species.

Grieves, (U) using the

same data, supplemented the original findings by describing
most of the

gross features, which were later borne out by

other workerso

The similarities and differences between human

and rat caries were noted with special regard being given to
the aspects common to both.

The features observed by Grieves

were penetration of the enamel, followed by spread in the den­
tin with subsequent fracturing.

These lesions have since been

observed by many workers, but seldom in that sequence.

He main­

tained that caries rarely involved fractured surfaces, but that
fractures often result from carious-like lesions.
In 1925 Hunting (5) reported caries in 31 of 66 rats fed
various diets.

Thirty of thirty-eight

animals on maize-contain­

ing diets developed caries in contrast to only 1 or 2 of 28 on
maisje free rations. He also observed that after eleven months
on a total meat diet animals showed very defective bones but no
caries.
Shibata (6) in 1929 fed weenling rats and older animals
a ration composed of rice, greens, sucrose, glucose, lactose,
and maltose.

He reported caries in 70-80$ of the animals with

seme lesions appearing as early as 20 days.

The ration was

reported less effective in the case of older rats and ineffec­
tive for animals started at 300 gms. body wt.
-U-

Later reports by the same worker (7) revealed that no
caries was produced by polished rice and dextrin.

He ascribed

caries production solely to the added sugars*
In 1932 Kesel (8) reported a repetition of Shibata’s work
with negative results, claiming that under similar conditions
no caries was produced and the rats showed marked undernour­
ishment.
Klein and McCollum (9) in 1931 studied 750 rat skulls and
concluded that the minimum time for caries production was 60
days on a ration that would produce caries in 88$ of the rats
in 81 to 155 days.

They observed that rats were usually 100

days old before any appreciable caries could be noted.
in sharp contrast to Shibata’s 20 day period.

This is

Klein and

McCollum later reported their ration as a rachitogenic one com­
posed of 76% maizft- 20$ wheat gluten. 1.5$ calcium carbonate,
and 1% salt.

They described and illustrated interproximal

caries, but made no mention of frequency relative to the occlu­
sal type.
Agnew, Agnew and Tisdall (10) in 1932 found caries in all
of .38 rats on a diet containing 78.>4$ of "finely ground" maise
over a test period rangeing from 2-6 months.

They also reported

caries production by a casein-starch-fat type ration low in phos­
phorous.

Carles, however, did not occur when this ration was

corrected for phosphorous and cane sugar was substituted for
starch.

From their extensive study of the mechanism of these

carious lesions and their resemblance to those of humans they
believed the process in the two species to be analgous*

Using

a rough quantitative method Johnston, Kaake and Agnew (11) in
1933 studied the oral flora of the rats of Agnew, Agnew, and
Tisdall,

They reported high counts of L. acidophilus in 27 of

30 rats with caries and low counts in the other 3*

Observations

made on 1£>3 rats having no macroscopic caries showed high counts
in 109 and low counts in the remainder*

These workers concluded,

therefore, that L. acidophilus isof little significance in the
etiology of rat caries*

It is important tonote, however, that

Johnston et. al. did not demonstrate the absence of microscopic
caries which detracts from their

conclusions*

The same group reported that no caries appeared in 18 rats
fed a ration containing 62% cane sugar for a period of many months
xne acidophilua couiit was high. iu 8 and Iwn

in 10 cf theseanimals

Toverud in 1926 (12) fed 100 rats a ration containing 92%
ground wheat and reported no carious lesions*
animals fed bread ad libitum plus

In a group of U

cc of calcium-poor milk

daily, however, he observed caries in all cases*

The animals

were kept on the diet from 3 weeks old to 3~k months and the
lesions varied from small fissures to wide openings with pulp
involvements*
Knowlton (13) in 1929-30 found no caries in 3k rats main­
tained on a casein-starch-fat type diet varying in vitamin B.
complex and vitamin D*

The animals were fed the ration from
-6-

weening to $0 days which is probably not long enough for caries
to derelop in common strains of albino rats*
Krasnow (lit) in 1932 studied the role of fluorine in dental
caries using rats as the experimental animal.

Eight groups of

ten animals each were used, but no caries data were reported.
Rosebury and Karshan (15) in 1931 failed to find caries in
any one of 60 rats fed rachitogenic, scorbutic, or high carbohy­
drate rations for from 1+0 to 60 days.

Half of these animals re­

ceived a gum tragacanth paste containing a human strain of
Bacillus acidophilus biweekly.

None of the rations contained

cereal particles.
Lilly (16) raised rats until 30 days of age on a stock
ration of fresh meat, whole milk, bones, bread, and cooked and
fresh vegetables.

After 30 days they were placed on a ration ofs
Starch.................. 53£
Lard
.... .
2%
Casein...... ......... 18/S
Osborne & Mendel salt... k%

with daily supplements of cabbage and brewers yeast.

Variations

of this ration were made by substituting sucrose for starch and
lettuce for cabbage.

Approximately half the animals received a

1 ml. of pure Bacillus acidophilus culture three times weekly
throughout the experimental period which was carefully rubbed on
the teeth and gums.

Sections were prepared of the jaws but no

carles was found in 52 rats after a 12 months experimental period.
Lilly also fed the Steeribock rachitogenic diet No. 2965 to
a series of ten rats until death or for 12 months.

No caries was

found, but no mention was made of the maize particle size*

These

results are somewhat contradictory to those of other workers and
i
detracts from the significance of Lilly's conclusions regarding
the inability of carbohydrate diets to initiate and develop
caries.

An explanation might lie in the possible inherent re­

sistance to caries of the rats used in his studies.
In 1932 Lilly and Grace (17) reported no caries development
in groups of ten rats on high carbohydrate rations for 6^ months.
These workers fed glucose, lactose and maltose at a 66% level,
the rations being balanced with 20% casein, 10$ lard, k% Osborne
and Mendel salt mixture, and viosterol.
rats developed no caries

Two similar groups of

in £§ months on rations low in fat,

namely: 73$ starch, 19$ casein, 3$ salt mixture and cod liver
oil or butter fat
THE DISCOVERY OF OUAttbE PARTICLE ETIOLOGY
An important contribution to dental caries study was made
in 1931-32 by Hoppert, Webber, and Canniff (18) who reported the
discovery of cereal particle size as an etiological agent in the
formation of caries in rats.

Upon failing to find cavities in

stock rats fed a ration low in calcium and vitamin D the control
animals were examined for comparison.

Extensive decay was obser­

ved and from subsequent studies they concluded that particle
size was a contributing factor.

Rations containing coarse corn

meal induced caries, those with corn meal that passed a 60 mesh
screen produced none.
“8—

A criticism of this work was offered by McCollum (9) who
suggested that the fine

c o m meal rations were richer in phos­

phorus than those containing coarse maize.

Hoppert, Webber,

and Canniff (2), and Webber (19) replied to this criticism by
showing caries production in rats on a c o m meal ration high in
phosphorous

as compared with an oatmeal containing ration which

caused no caries.

These authors ascribed the origin of caries

to the impaction of c o m meal particles in the sulci of the rat
molars with subsequent fermentation and erosion of enamel by the
acid produced.
In 1933 Klein and McCollum (20) agreed to the etiological
effects of coarsely ground maize after finding caries in 22 of
3U rats on the Steeribock and Black rachitogenic ration No. 2965,
but none in 7 rats on the same ration ground to pass a 60 mesh
screen.
The composition of the H-W-C ration is as follows:
Yellow maize meal..........60%
Whole milk powder......... *30%
Lindseed meal............... 6%
Alfalfa meal
........ 3%
Sodium chloride.......... 1%
The approximate distribution of maize particles in this
ration was b$% on a 20 mesh screen, 30% on a 1*0 mesh, 12% on a
60 mesh, and 13% through a 60 mesh«

A simplified formula of the

above ration replaces the lindseed meal with the cereal in ques­
tion.

Hoppert, Webber and Canniff in 1932 also reported that the

replacement of maize by rice induced caries in rats, but that

oatmeal or hard wheat was ineffective.
The etiological significance of particle size has been
confirmed by Klein and McCollum. (20), by Shelling and Asher (21),
Rosebury, Karshan and Foley (22, 23, 2k, 25),Bibby and Sedwick
(26), Lilly and Wiley (27), King (28), prior to 1936 and by many
others since.
THE RELATION OF FLUORIDES TO DENTAL CARIES
Historical
A survey of dental history reveals that at sometime or other
almost every element known to be present in dental tissue has been
suspected of bearing a relationship to dental caries.

Some attri­

buted the phenomenon to an excess of the element involved whereas
others ascribed it to a deficiency.
Relative to fluorine, seme of the more pronounced effects
were observed and described before the etiological agent was
known.

In 1916, McKay and Black (29) described the hypoplastic

nature of mottled teeth and studied degrees of its severity.
Later, by feeding various levels of potassium fluoride, Cheyne
(30) produced graded mottling in rat molars.

Previous to Cheyne,

Smith, Lance and Smith, and Churchill, working independently,
showed a similar effect caused during the calcification process of
the tooth try the incorporation of excessive amounts of fluorides
in drinking water.

Cox, Matuschak, Dixon, and Walker (31) reported

a milky appearance in rat molars fed various levels of fluorine
during the suckling period.
-10-

These studies established a relationship between the
fluoride intake and the general appearance of dental tissue
and suggested a possible influence of fluoride on tooth decay*
In 1933 Armstrong (32) fed rats a ration containing 1000
ppm. sodium fluoride for three weeks and then discontinued the
fluoride.

During the three weeks following the fluoride-free

intake he reported the breaking off of the upper incisors-near
the gum line.

Armstrong and Brekhus (33) in 1938 showed that

transverse bands of mottled and normal enamel may be produced
and that the previously reported breaking off seems to take
place at a band of normal enamel*

This information suggests

that fluorine acts as a hardening agent when incorporated in
dental tissue.
In 19la Arnold and McClure (3U-35) injected sodium fluo­
r i d e in rats

Ttiain+.aineri

level in intake

nn the H—W —0

simplified ration*

The

in these animals was approximately equivalent

to itO-50 ppm fluorine daily in water*

No caries was reported*

At the same time no reduction of caries was observed in another
series of rats fed 10 ppm fluorine in the drinking water*
Twenty-one litters were used in this investigation and analyses
of the teeth revealed a four-fold increase of fluorine in the
latter group.

McClure (36), however, in 19hl reported a marked

reduction of caries in rats maintained on $0 and 100 ppm
fluorine in water.

He stated, "Posteruptive deposits of fluorine

may not increase the tooth's caries resistance".
-11-

In 1939 Cox, Matuschak, Dixon, Dodds and Walker (3?) studied
effects of fluorides on pre-eruptive dental tissue by raising
control rats on a ration composed of sucrose, casein, crisco and
salt mixture, supplemented with yeast, alfalfa and Haliver oil.
Experimental rats received Ul.2 ppm fluorine as sodium fluoride
and their

offspring were placed on the H-W-C ration for

a

standard period of eight weeks after weaning.
Experimental
The purpose of this series of experiments was to establish
any caries inhibiting effects of fluoride in a caries susceptible strain of rats and to study such effects on the dental
tissues at various stages of the development of the teeth.
The chronological development of rat molars as presented by
Cheyne (30) was used as a guide in this study, the periods of
primsry interest being (1) that previous to dental development
or the inutero phase (2) the period of major development or that
during lactation, and lastly (3) the final stages of molar growth
and maturity where the vital nature

of dental enamel is some­

what controversial.
To accomplish certain phases of this study litters were
divided at birth into two groups, one group remaining with the
mother and the other
ing female.

group being transferred to another lactat-

Elaboration of this technique will follow with

specific detail.

-12.

PART I
EFFECT OF CONTINUOUS FLUORIDE FEEDING
As a general approach to the overall problem, rats were
given

a fluoride supplemented diet throughout the experiment.

This was accomplished by feeding the mothers a fluoride supple­
mented ration and continuing the offspring on the same diet.
Previous work by the author as well as McClure and Arnold (36),
and Miller (38) established an effective fluoride level at
approximately 123 ppm of NaF in the ration.

For this part of

the experiment and for all others in this thesis the fluoride
enriched ration consisted of the H-W-C fine rice formula plus
123 p.p.m. NaF.

At this level of intake normally growing rats

usually showed bleaching of the incissors but no severe fluorosis.
For controls, offspring of litter mates were fed the H-W-C
fine rice ration.

As previously explained, the homozygous

nature of the susceptible strain justifies this procedure.

The

lower molars were observed at approximately 2 wk, intervals and
the caries initiation and progress recorded at three phases of
development.
From the accompanying tables (Table I) it will be observed
that the controls showed initial caries between 33-60 days of
age with moderate or severe involvement

following in two weeks.

By way of comparison the fluoride animals reveal initial caries
between 7h and lUO days of age with moderate caries at 7l| to
172 days.

In several cases severe cavitation was delayed far

200 days.
-13-

TABLE I
EFFECT OF CONTINUOUS FLUORIDE FEEDING

Litter
Number

Rat
#

Diet

Caries Time in Days#
Initial Moderate
R
L
R
L

11aF(9-20)

H 4O
1
Ff
tt
H 4O
2
11
120
3
11
120
14
n
120
5
Average of L Sc R sides (136)

185
lUO
— •
H 4O
120

172
—
—
H 4O
75
—
lUo
H 4O H 4O

Severe
R
L
200 200
172 172
172 172
172 172
172 172
(176)

12F(8-12)

6
F
11
7
1
1
8
Average of L & R sides

11H llU 138
114 138 138
11I4 llU 138
(118)

138
—
138

160 160
160 160
160 160
(160)

F
9
11
10
11
11
i
t
12
n
13
it
114
11
15
i
t
16
Average of L & R sides

-nm
7k
—
62
86
86
7U
100 125 125
—
7U
7k
100
7k
86
86
7k
—
86
7k
(81)

7U

86
86
86
86
100 100
1U6 Hi6
86
86
II46 1I46
100 100
125 125
(109)

F
17
n
18
i
t
19
1
!
20
I
t
21
It
22
II
23
Average of L & R sides

78
78
—
136
136 Ilk
136
100
78
78
78
78
(99)

12F(8-25)

12F(9-27)

c**
214
n
25
11
26
i
t
27
i
t
28
11
29
n
30
Average of L k R sides
114(8-11)

U8
35
35
35
35
35
35
(39)

60
1*8
35
—
—
35
—

__
_
86
—

100 100
168 168
168 136
168
—
128
100 100
«—

U8
~
k&
—
U8

—
__
—
i|8
—
U8

IU4 nit
180 180
168 168
168 168
168 168
llU 111*
100 100
(1U5)
60
60
1*8
1*8
60
I48
60

60
60
148
1*8
60
ii8
60

(5 5 )

f Fluoride Ration (Fine rice ration plus 125 p.p.m. NaF).
■5'™- Fine rice cariogenic ration (Control)
-lit-

I

TABLE I (Cont'd.)
EFFECT OF CONTINUOUS FLUORIDE FEEDING

Litter
Number

Rat
#

Diet

C
31
ii
32
t
i
33
n
3k
it
35
ti
36
M
31
Average of :L & R sides
12(8-23)

Caries Time in Days
Initial
Moderate
R
L
R
L
62

71*

62
62 62
62 62
62 62
62 62
«_
(63)

C
it
it
it
n
1+2
it
U3
t
i
1+1+
Average of !L & R sides

50
50
50
50 —
50 —
62 62
62 62
(55)

12(10-9)

k9
50
n
51
Average of ;L & R sides

37
52 —
ip'
?
ea. pt
37 —
37 —
37 — 37 —
(U3)

Total Mean
F
it
it
C
Mean Difference «

(109)
( 50)
59

12(9-6)

38
39
ko
kl

1+5
1+6
L*?
1+8

C
n
•>
n
it
«

7h
62
—
—

—

—
—

—
—

—
62
—
—

—
—
—
62
—
—

52

52

*****
—
—

—
—

52
52
52
52

— ."

52
52
—

Severe
R
L
86 86
YU 71+
7k 7k
7k 7k
7k 7k
7k 7k
62 62
(7k)
62
62
62
62

62
62
62
62

71+
71+

71+
71+
71+

7k
(67)

76 76
76 76
TO 70
76 76
76 76
76 76
76 76
(76)
(11*8)
( 68)

80

PART II
PRENATAL EFFECTS OF FLUORIDES

{

This part of the experiment was set up to study the effect
of limiting fluoride to the prenatal period*

The fluoride

ration was fed to susceptible breeding stock and the offspring
divided into two groups at birth*

One group was left with the

original mother whereas the other was nursed by a mother main­
tained on the basal ration* Accordingly the first group received
fluoride throughout the experiment, the seerid, only during em­
bryonic and fetel development.

Any differences between these

groups would be due therefore, to placental transfer of fluoride.
The seven control animals

from the three litters used in

the experiment gave responses that were characteristic of the
susceptible strain of rats in that the average caries initiation
time K8.B yo days from birth*

Severe involvement followed at

77 days in every case.
Data presented in Table II reveal that 6 of the 12 supple­
mented rats showed no lesions in 200 days, the minimum initiation
time being 118 days.

In this experiment the study was terminated

in 200 days therefore making it impossible to determine average
carles initiation time.

-16I

TABLE II
PRENATAL EFFECTS OF FLUORIDES

Litter
Number
31F(7-6)

31F(7-13)

31F(7-7)

Total Mean

k

f

Rat Diet
#
1
2
3
k
5
6
7
8
9
10
11
12
13
lit
15
16
17
18
19
20

C*
Ff
ti
ti
ii

C

Initial
R
L

Tlrl
60 60
77 77
Caries free at 200 days
lk6
—
132
1I46 11*6
118 118
118
132
Caries free at 200 days
M _1|

ii

kk
60

F

—

ti

60

kk
60

10k
10U
Caries free at 200 days
—

ii

it
ii

it
ti

ii

ii

it

a.
F
n
ii

it

C
F

60
—

it
n

C
C

Severe
R
L

Moderate
R
L

n
11
ti

11
11
n

77 77
77 77
160 160

11
n
n

—•
60
60
77 77
—
60
60
77 77
—
60
60
77 77
—
60
60
77 77
160 160
118 118
17k 171+
160 160
17k 17k
118 118
Caries free at 200 days
200 200
—
—
—
—

(58)
(77)
Cannot be determined due to the
caries-free rats at the termination of the experiment.

Fine rice control ration.
Control ration plus 125 p.p.m. NaF, fed all animals
prenatally and to the "F" animals throughout the
experiment.

-17-

PART III
LACTATION AND POSTWEANING EFFECTS OF FLUORIDES
In order to elaborate further the ineffective nature of
fluorides on teeth in the prenatal stage a study of the lacta­
tion and postweaning periods was conducted.
Offspring born of susceptible animals fed the basal fine
rice ration were divided into two groups at birth.

One group

remained with the original mothers while the other was trans­
ferred to stock mothers receiving the fluoride ration.

The first

group served as a control whereas the second received the fluo­
ride ration throughout the experiment.
The data recorded in Table III shows that the control animals
developed caries in the expected time.

The fluoride animals, on

the other hand remained caries free for 165 days when the experi­
ment was terminated.
PART IV
POSTWEANING EFFECTS OF FLUORIDE
The final phase in the fluoride experiment concerned a study
of withdrawing fluoride from rats which had received fluoride
during the prenatal and lactation period.

This was done by feed­

ing the fluoride fortified H-W-C fine rice ration to susceptible
breeding stock and continuing the offspring on the same diet
until the time of weaning.
into two groups.

At this point the litters were divided

One group was continued on the fluoride ration

whereas the other was placed on the standard fluorine-free basal
-18-

TABLE III
LACTATION AND POSTWEANING EFFECTS OF FLUORIDES
Caries time in days
Litter
Rat Diet
Initial
Moderate
Severe
Number __ # ___________ R
L______R
L______ R
L
32(12-1)

1
2
3
k

Cmtt
it
Ff
y

kZ(H-2k)

5
6
7

0
F
it

U2(11-28)

8
9
10
11
12
13
Ik

C
tt
tt
F

15
16
17
18
19
20
21
22

C
ti
it
tt

23
2k
25

32(12-5)

1*7(12-11)

Total mean

70 -82 82
82 —
Caries free

—
82
96
t—um
96
—
—
96
at 165 days,P

96
96
96

100 100
- 76 88
88
88
Caries free at 165 days,•
n
n
tt
it n

60 60
—
—
73 73
—
— »
60 60
Caries free at 165 days
n
it
it it n
tt
it tt w
tt
tt n
n
it
tt

73
85
73

73
85
73

92
92
92
92
92

92
92
92
92
92

F
tt
it

—
66 78
78
78 78
92
—
78 78
.
.
.
78 78
—
—
78 78
Caries free at 165 days
tt
tt tt tt it
tt tt it tt
tt

r
U\
n
F

£r\ ——
70
W
f«m
100 100
60 —
100 100
72
Caries free a t 165 days

c

(73)
(93)
Observations relative to this
thesis were stopped at 165 days*

tt

it
tt

it

F

# Fine rice control ration.
f Control ration plus 125 p.p.m. NaF fed the "F" animals
from birth throughout the experiment.

-19-

ration*

The rats were observed as usual and the caries progress

recorded.
Table IV shows, with very few exceptions, that the control
animals developed moderate to severe cavatation in 73 to 98 days.
The fluoride supplemented animals, on the other hand, showed
minimum initiation at 133 days with moderate to severe involve­
ment between lf>8 and 277 days.

Similar results were obtained with

four additional litters from separate families, making a total of
18 controls and 19 supplemented animals.
DISCUSSION OF FLUCRIDE RESULTS
A susceptible strain of rats was used to study the effects
of fluorides on teeth at various stages of development.

A cario-

genic fine rice ration fortified with 12f> p.p.m. sodium fluoride
had a marked inhibiting effect on the caries initiation time when
fed to mothers during the lactation period and continued with the
weenling rats.

Rats discontinued on this ration at weaning time,

however, showed early cavatition and rapid progress of
following

initiation*

caries

The fluoride ration fed only during the

prenatal period transmitted no caries inhibiting effect on the
offspring.
The schematic

chart reveals that the

caries progression

time, or the time required for lesions to proceed from the initial
to the severe stage, was approximately the same regardless of
the initiation time.
-20-

TABLE IV
POSTWEANING EFFECTS OF FLUORIDES
Litter
Number
31F(5-12)

31FC5-6)

31F($-13)

31F($~18)

31F(5-17)

Total mean

Rat
#
1
2
3
k
5
6
7
8
9
10
11
12
13
1U
15
16
17
18
19
20
21
22
23

Diet

Caries time in days
Initial
Moderate
R
L
R
L

0*

rt-t

it

_

Ff
it

2U0 2I4.O
158 158

73

73

_

186

186

C

« n

mmmm

----rr

u

_

—

73

73

—

—

— .

—

n

98

98

ti

—

— .

F
it
ii

C

133 133
158 158
158 158

F

73
73
73
73
158 158

C

----T

ii

ii.

F
n
ii

C
F
ii
ii

0
F

186 186
158 158
—

186 186
—

Ihh lUU
200 200
158 158

—

158 158
— .

—

186 186

—
-M73
73
Caries free at 227 days.
200 200
186 186
200 200
215 215

(_)
(172)

Severe
R
L
98
98
252
200

98
98
252
200

73
98
111*
73
158
200
172

73
98
11U
73
158
200
172

98
98
98
98
died
73
73
73
73
227 227
215 215
200 200
98

98

215
227

215
227

(90)
(197)

-a- Cariogenic fine rice ration fed to half of the animals
after weaning*
t Cariogenic fine rice ration fortified with 12$ p.p.m.NaF
fed to all animals until weaning time and to half of
them throughout the experiment*

-21-

In terns of tooth development it would appear that the
nearly mature dental tissue derives a great deal of protection
from the fluoride fortified ration,
Gerould (39) holds the view that fluorides, when incorp­
orated in the appetite structure of the tooth, exhibit a surface
bacteriostatic effect and thus are instrumental in lowering the
acid production.

He also showed that finely divided dental

tissue exposed to fluoride solutions was more resistant to solu­
tion by than similar material not treated with fluoride solutions.
If the results observed in this study are the result of
systemic transfer of fluorides it is suggestive that dental enamel
is composed of vital tissue and that the fluoride turnover is
rapid.

On this basis it might be expected that the progress of

decay to the severe stage would be slower than that in control
animals.

The data, however, show no consistent or striking dif­

ferences to support this view.
The caries inhibiting effect of fluorides may also be attri­
buted to the antibacterial or antienzymatic
element.

properties of the

To be effective this mechanism would have to provide a

fairly continuous exposure of the enamel surface to fluorides.
It also follows that withdrawal of fluorides would again make
the teeth vulnerable to decay.

The latter explanation finds sup­

port in the early development of caries in the rats which were
removed from the fluoride supplemented ration after having

had

the benefit of prenatal and postnatal fluoride applies up to the
time of weaning.
-22-

The

favorable results that have been obtained from the

continuous feeding of fluorides to rats with a high degree of
susceptibility to caries indicate that the program of supply­
ing

a fluoride enriched source of water for general use in

certain communities should be attended by considerable improve­
ment in the conditions of the teeth of the human population.

-23-

SCHEMATIC CHART

Number
of Rats

Average
Caries time in days
Initial Severe Progression

I Effect of Continuous
Fluoride Feeding
109
II Prenatal Effects of
Fluoride
(50% Caries free at 200 days.
(Earliest initiation at 118 days
III

rI-o
jrI

Lactation and Postweaning Effects of
Fluorides
100$ Caries free at 165 days
11

IV

Postweaning Effects
of Fluoride

1?2
in utero lactation
(21 days) (20-25 days)

postweaning

lotal number of animals — 120

197

CONCLUSIONS
1)

Caries susceptible rats receiving fluorides only during
embryonic development showed no resistance to dental
caries.

2)

Susceptible rats continued on a fluoride ration through
the lactation period showed no increased resistance to
caries.

3)

Susceptible rats continued on a fluoride ration after
weaning showed marked resistance against tooth decay.

U)

From these observations it follows that to be most effec­
tive fluoride supplementation must be continuous.

-25-

THE RELATION OF CARBOHYDRATES TO TOOTH DECAY
Historical
Some of the earliest observations regarding sugars and
starches as etiological agents in dental caries were made by
Shibata (6) in 1929 who fed young and old rats rations

contain­

ing 5 to 10$ of sucrose, glucose, lactose and maltose.

He re­

ported caries in 70 to 80$ of the animals, appearing as early
as 20 days and attributed the causal effects to the added sugars.
In 1930 Shibata (7) added further that no caries was pro­
duced by, ’’polished rice or dextrine".
Other investigations, however, have failed to substantiate
Shibata's findings.

Kesel (8) in 1932 wrote, "I have repeated

Shibata's experiments not once but on four different groups of
animals. — —

Bacillus acidophilus was quite regularly found

in their mouths} but not one ret developed one decayed molar".
Further discriminating evidence was produced by Rosebury,
Karshan and Foley (22) in 1933 who established that the causal
factor in Shibata1s rations was coarse rice and not the added
carbohydrate.
Johnston, Kaake and Agnew (11) in 1933 reported that no
caries was developed in a series of 18 rats fed a diet of 62$
cane sugar for many months.

The acidophilus incidence was high

in eight and low in ten of these animals.
Rosebury and Karshan reported no caries in 60 rats fed
high CH0 rations for from U0 to 60 days.
-26-

Half of these animals

received an oral inoculation twice weekly of a human strain of
Bacillus acidiophilus.
the ration*

They reported no cereal particles in

It is questionable in this work if the term of the

experiment was long enough to permit conclusive results*
and McCollum, in this connection, studied 750 rat skulls

Klein
in

1931 and concluded that it was necessary for a rat to be at
least 100 days old for any significant carious lesions to appear.
In 1933 Bream and Tisdall (I4.0) reported, "Sugar, so long
blamed for caries, has been proved harmless in the rat, to which
diets have been given containing as high as 62% carbohydrate but
including also adequate minerals and vitamins"*
King (28), in 1935 fed rations containing 62.5$ carbohydrate
to rats for 396 days after weaning.

Corn starch, rice starch,

and sucrose were the carbohydrates used in these experiments.
He reported the rations as being low in Ca, P and vitamins C and
D, but that no caries was observed.
In 1935-35, Day, Daggs and Sedwick (51-52) added commercial
fudge to fox chow at 20$, 35$ and 55$ levels.

Additional vitamins

and minerals were provided for some of the 55$ group.

213 animals

of varying ages were vised and the experimental period ranged from
150 to 213 days.

They reported the incidence of 5 carious lesions

in the entire group but no relationship could be established to
the rations used.
Lilly and associates (16) were unable to find a single
lesion in more than 350 rats to which rations had been fed
-27-

containing 66% glucose, sucrose, lactose, maltose and corn
starch.

The rations were fed for periods of 6|- months to a

year.
Cox (U3) in 1938

indicated that sucrose and glucose

do not initiate caries in rats but that they promote caries
previously initiated by the H-W-C ration.
PART I
A study of the effect of diets containing finely ground
rice, sucrose and no fermentable carbohydrates on the product­
ion of dental caries.
Experimental
The majority of investigations in which readily ferment­
able carbohydrates have been fed to rats lead to the conclu­
sion that sugars do not initiate dental caries.
with stock animals,

In seme cases

however, sugars have proved to be caries

promoters once the lesions have been initiated by
cereal particles.

coarse

It was thought advisable, however, to re­

evaluate this work using the caries susceptible strain of
rat as the experimental animal.
Three rations were used in this study, the H-W-C fine
rice ration which served as a control diet, a complete ration
containing 50% sucrose, and a third ration composed largely
of lard, casein, and alfalfa which was considered to be essen­
tially free of fermentable carbohydrates.
these rations is herewith given.
-28-

The composition of

I
II

The H-W-C fine rice ration (previously described)
The fat ration
casein.
....... .1*0$
alfalfa.............. 30%
brewers yeast......... 9%
salt................ 1
fat (lard or crisco)...20$

III

The sugar ration
sucrose.............. 50%
casein.•••.. ......... 10J6
alfalfa.
....... 6%
brewers yeast.......... 3%
salt.
.... 1%
powdered whole milk....30%
The mothers were raised on the control ration until the

offspring reached ll±-l5 days of age.

At this time the families

were transferred to clean cages and placed on the fat ration.
At this age the young rats still rely on the mother's milk for
nourishment, therefore the chances for
producing ration are negligible.

exposure to the caries

The animals

were

maintained

on the fat ration until several litters had reached the weaning
period.

Each litter was then divided three ways with sexes as

evenly distributed as possible.

The three rations described

above were fed ad libidum to the respective groups throughout
the remaining term of the experiment.

Caries initiation and

progress were recorded and appear in table V.
Since litter mates were used throughout this experiment
the data are recorded in litter groupings to facilitate inter­
family comparisons.

Severe caries was produced in the control

animals between 6k and H O days.

In sharp contrast to this

-29-

short period the rats receiving the sucrose containing diet
showed severe caries at an average of 210-230 days with the
earliest appearing at 12k days*
The rats fed the fat ration remained caries free as long
as they were kept on this ration.

At 10 months to a year ap­

proximately half of these animals were transferred to the
H-W-C fine rice ration*

Table V indicates that from 130 to

180 days were required to produce severe caries in these
animals with 117 days being the minimum time.

It is of inter­

est to note that even though the initiation time was longer
with the adult animals the progress of caries to the severe
state was still rapid*

In every case the animals remaining

on the fat ration showed no sign of caries during their entire
span of life.
In addition to the animals recorded in the table, a litter
of three females and three males were maintained on the fat
ration throughout their life spans, the purpose being two­
fold5 namely, to obtain further evidence that rats of a caries
susceptible strain would develop no caries on this diet and to
study the caries susceptibility of the offspring of these rats.
Sixteen young from this mating were divided into two groups
at weaning.

One group remained on the fat diet whereas the

other was fed the fine rice ration.

Caries developed as usual

in the latter group whereas the other, fed the fat ration,
remained caries free.
-30-

TABLE V
THE EFFECT OF DIETS CONTAINING SUCROSE AND NO FERMENTABLE
CARBOHYDRATES ON THE PRODUCTION OF DENTAL CARIES
Litter
Number

Rat
Diet
#_______

Caries time in days*
Initial
Moderate
R
L_______R
L

Severe
R
L
71* 71*
71* 71*
121* 121*
170 170
150 150

1
2
3
k
5

C
C
S
S
Fat*

60
60
7k
11*8
130

6
7
8
9

C
S
S
Fat

60 60
170 170
192
—
170 170
192 192
Caries-free for life span

19(8-29)

10
11
12

C
S
Fat

88 88
110 110
190 190
230 230
177 177
Caries-free for life span

7(9-9)

13
1U
15

C
S
Fat

88 88
190 190
Caries-free for life span

110 110
230 230

16
17
18
19

C
S
Fatf
Fat

60
60
178 —
200
—
130 130
Caries-free for life span

90 90
222 222
150 150

20
21
22
23
2l*

C
C
s
Fatef
Fat

25
26

101* 101*
S
117 117
Fatf
12*1* 11*1*
Table V Cont’d next page

10(7-8)

6(7-15)

7(6—lh)

10(6-21)

9(6-5)

60
60
7k
11*8
130

_____

~

—

110

110

—

—

—

—

M

M

—

•

71* 71*
210 210
210 210

— —

—

M

M

—

„

—

—

~

cassa

ess*w»

60
—

60
101*

117 —
130 130
Caries-free for life span
—

—

—

.

76 76
76 76
139 139
150 150
139 139
180 180

* Time starts when animals were changed from the fat
ration to the experimental ration*
* Changed to the fine rice cariogenic ration after 10-12
months remaining caries-free on the fat ration. Caries
time is calculated from the time of this change.

-31-

TABLE V (Cont’d)
Caries time in days#
Initial
Moderate
Severe
R
L
R
L_______R
L

Litter
Number

Rat
#

Diet

10(7-2)

27
28

C
Fat

mmm
mmmm
62 62
Caries-free for life span

6(9-11)

29
30
31

C
C
Fat

—
110 110
88 88
H O 110
50 —
6h
Caries-free for life span

19(9-12)

32
33

3U

C
S
Fat^

35
36

C
Fat

10(9-18)

Mean Average

C
S
Fatf

mrr

6k —
132 —
117 117

16U
—

76

76

no no

—

230 230

—

130 130

110 110
88
6k k9
6k
Caries-free for life span
92
190

1U6

* Time starts when animals were changed from the fat
ration to the experimental ration*
f Changed to the fine rice cariogenic ration after 10-12
months remaining caries-free on the fat ration. Caries
tiiuo is ualuulateu Ix*uui the time ox this change.

-32-

I

PART II
The influence of rice on the caries producing effects
of Sucrose.
The purpose of this study was to investigate the possi­
bility that the fine rice ration might serve as a caries ini­
tiating agent after which the effects of sucrose might be more
pronounced than had been observed when rats were placed direct­
ly on the sucrose diet after weaning.
Five litters numbering 21 animals were used in this study.
The young were b o m at approximately the same time and were
placed on the fat ration at 11+ days of age. When the youngest
litter had reached the weaning stage all of the litters were
divided into two similar groups.

One group received the fine

rice ration for two weeks and was then changed to the sugar
diet whereas the other group remained as a fins rice control.
Rat molars exposed to the fine rice ration for only two weeks
reveal no macroscopic caries.
Observations for lesions were made and recorded at two
week intervals.

The control animals showed initiation of

caries at 38 to 87 days which is a considerable variation
the susceptible strain.
and 130 days.

for

Severe caries developed between 87

When comparisons are made strictly within

litters, however, it

is evident that caries initiation and

development in this experiment were earlier and more rapid
than in Part I in which preliminary exposure to fine rice
-33-

was lacking.

Severe caries with this somewhat less susceptible

group fed the sugar ration developed in 162 days as compared
with 190 days for the animals in Part I fed only the sucrose
ration.
Discussion
Perhaps the most outstanding

conclusion to be drawn from

this series of experiments is that a sucrose ration in the
absence of cereal particles* large or small* can act as a
caries initiating as well as promoting agent in rat molars.
This fact has been denied by many workers referred to in the
historical section.

In view of the relatively long period of

time required to effect macroscopic caries in the susceptible
strain of animals it is not surprising that the factor has been
overlooked by workers using ordinary stock albino rats.
The caries promoting character of sucrose following initia­
tion by the H-W-C ration as reported by Cox (1*3) is clearly
supported by Part II of this series.

Apparently the diet con­

taining finely ground rice used with a susceptible strain of
rats produced microscopic lesions during the two week period
of exposure* so that the subsequent effect of sucrose was
markedly accelerated.
It is significant also that even though the caries initia­
tion time was markedly longer with the sucrose ration as com­
pared with the fine rice ration* the time required for the
lesions to proceed from the initial macroscopic stage to the
-3U-

TABLE VI
THE INFLUENCE Off RICE ON THE CARIES PRODUCING EFFECTS
OF SUCROSE
Litter
Number
16 ( 9 - 21+)

19(9-25)

13(5-20)

19(9-22)

Rat
#

Severe
R
L

c
c
s
s

38 87
63
63 ~~
108 108

1+1
1+2
1+3
1+1+
1+5
1+6

c
c
c
s
s
s

87
38
38
108
63
63

1+7
1+8
1+9
50

c
c
s
s

87 __
63 —
108 108
87 87

M,
mmmm
—
108
—■ —
108 130

51
52

s

63
108

78
130

51+
55
56

57

*

Caries time in days*
Initial
Moderate
R
R
L
L

37
38
39
1+0

13 ( 10 - 6 )

Mean Total

Diet

c

87
63
63
108
«_
63

,

n
c
c
c
s

An An
V,/
63
63
63 108
87 87

c
s

85

61+

87
On
Of
108
130

—
108
130

108
108
162
162

108
108
162
162

63
63
130
87
87

87
—
130
87
—

108
108
87
162
162
162

108
108
87
162
162
162

108
130
162
162

130
162
162

130
162

130
162

art
V
I
108
108
162
162

0**7
v
1
108
108
162
162

, .

87
87
108
130

78
130
____

87
—
—
130

108
162

Time was calculated from the beginning of the fine
rice feeding. The animals receiving the sucrose
diet were fed the fine rice ration for 2 weeks only.

-35-

severe stage was practically the same for the two rations.
This suggests that the chemical and

bacteriological factors

involved at the enamel surface are similar in both cases.
The difference between the two in initiating caries is prob­
ably due to the tendency of the cereal particles to impact
in the oclusion surfaces of the teeth thus bringing the acids
of fermentation into more intimate contact with the involved
surfaces.
The fundamental role of fermentable carbohydrates in con­
tributing to the production of

caries finds further support

in the failure to develop caries at all with the fat ration.
These results possibly justify the practice of certain dentists
in prescribing diets low in sugars and starches to patients
with rampant caries.

It is therefore inconceivable that dental

caries could develnn in the absence of some source of ferment
able carbohydrate in the food supply.

-36-

CONCLUSIONS
1)

Caries susceptible rats fed an essentially fermentable
carbohydrate-free ration remained caries-free throughout
their life span.

2) Animals of the caries susceptible strain consistently
developed carious lesions when fed a diet containing $0%
sucrose.
3)

Caries was slow to become initiated on a $0% sucrose
ration but proceeded to a severe stage rapidly.

k)

Caries susceptible rats fed a sucrose ration developed
caries more rapidly if previously fed a fine rice ration
for two weeks.

5) Rats kept caries-free for a year by feeding a fat ration
were slow to initiate caries when fed a fine rice cariopugicoo ua
the severe stage, however, was rapid.

-37-

xrtau x>ne xmi/XcUL x>o

THE INFLUENCE OF POWDERED WHOLE MILK,
EVAPORATED MILK, AND EVAPORATED MILK PLUS SUCROSE
ON THE PRODUCTION OF DENTAL CARIES
In view of the wide spread use of milk in the human
diet it was of interest to study its effects on dental caries
production in the susceptible strain of rats*

Two types of

milk products were used$ namely, powdered whole milk and
evaporated milk.

Evaporated milk was used in preference to

fresh whole milk because of its higher dry matter content.
The evaporated milk was limited to popular brands and was fed
as the only source of nourishment.

The powdered milk was used

in a ration consisting of ^9% powdered whole milk, 20$ alfalfa
meal, and 1% sodium chloride.
In the case of the powdered milk study 3 litters compris­
ing lU susceptible animals were raised until llt-lf> days of age
and placed on the

fat ration as previously described.

When

all were weaned they were then divided into two groups.

One

group received the powdered milk ration whereas the other was
fed the fine rice control ration.

The caries time recorded in

Table VIII reveals the response of the control animals to be

characteristic of the strain.

In contrast all of the animals

fed the powdered milk ration remained caries-free during the
entire period of observation of 160 days.
Twenty-nine susceptible rats from six litter matings were
treated in a similar manner to those above except they were
divided into three groups.

One group served as a control

whereas the other two were fed evaporated milk and evaporated
-38-

TABLE VIII
THE EFFECT OF POWDERED WHOLE MILK OH THE PRODUO
TION OF DENTAL CARIES

Litter
Number

U3(n-i?)

Rat

i

Mean total

*

Severe
R
L

5k 5k
5h 5k

6
7
8
9

C
C
c
P.M.
P.M.
P.M.

5k 5k
5k 5k
5k 5k

10
11
12
13
Hi

C
G
C
P.M.
P.M.

—
66 66
66 66
_
—
66 66
Caries-free for 160 days
it
11
II It It

C
P.M.

78
58
All animals remained caries-free
for 160 days.

3

ill(11-19)

Caries time in days*
Initial
Moderate
R
L
R
L

C
C
P.M.

1
2

1*3(11-7)

Diet

U
5

66
66

66
66

82
82
82

82
82
82

82
82
82

82
82
82

wmmm

—

_

Caries-free at 160 days
66

66

—

—

Caries-free for 160 days
n
ti 11 it it
ti
ti n
n
11
m—

Caries time calculated from the beginning of the
experimental ration.

-39-

milk plus 10% sucrose.

Table IX shows that the animals fed
i

condensed milk, either with or without sucrose, produced no
caries throughout the entire 190 day experiment. Most of
the animals, however, became emaciated and developed symptoms
of anemia during the latter part of the study.
Discussion
The results of the feeding tests with evaporated milk
and powdered whole milk indicate that milk products contri­
bute little or nothing to the

development of caries in a

highly susceptible strain of rats.
interest because of

This is of particular

the importance of milk in the human

diet especially during the early period of life when caries
in humans is particularly evident.

It is quite likely that

milk which has an inherent tendency to undergo an acid fermen­
tation under favorable conditions of temperature and the
presence of acidogenic bacteria does not remain in contact
with any of the dental surfaces long enough to cause decay*
Whether milk might contribute to the extension of cavities
has not been proven by these experiments.

This should be

one of the first tasks in further studies of the general
problem of tooth decay.

TABLE IX
THE EFFECT OF SWEETENED AND UNSWEETENED CON­
DENSED MILK ON THE PRODUCTION OF DENTAL CARIES

Litter
Number

Rat
#

37(8-25

15
16
17
18

C
S.M.f
U.S.M.

39(8-25)

19
20

38(8-28)

3l*(9-7U)

32(10-11)

32(10-11+)

Mean total

Diet

Caries time in days*
Initial
Moderate
R
L
R
L

Severe
R
L

90
90
?l* 7k
Caries-free for 190 days
11
n
11
it
ti
11
ti
it
it
it

120 120

C
S.M.

80 80
95
Caries-free for 190 days

120 120

21
22
23
2l*

C
S.M.
S.M.
U.S.M.

...
120 120
95 95
Caries--free for 190 days
11
it
11
11
11
ti
ti it
11
ti

25
26
27
28
29
30

C
C
S.M.
S.M.
U.S.M.
U.S.M.

31
32
33
3k
35
36

C
C
S.M*
!t
U.S.M.
ti

37
38
39
1*0
ia
1*2
k3
hk

68
68
91* 91*
—
106 106
9k 9k
80 80
106 106
91* 91*
Caries-■free for 190 days
11
n
•1
11
n
11
it
ill
n
it
ti
UUS.M.
11
11
ti
11
11
11
11
11
n
11
ti
11
c
81
102
S.M. Remained caries-free for the 109 day experiment
11
11
11
ti
11
U.S.M.
"
"
"

11

C
c
c
S.M.

90
90
78
78
Caries--free for 190 days
11
11
it
11
11
11
11
11
n
n
11
11
11
n
11
—

—

—

—

__ _____

«•••

—
—
68 68
Caries-free for 190 days
n
it
11
11
ti
ft
11
11
11
n
!!
1!
11
II
18
--

1

*Caries time calculated from the beginning of the
experimental rations,
f S.M. ■— sweetened milk
U.S.M. — unsweetened milk
-1*1-

120 120
90 90

68
80

68
80

I

CONCLUSIONS
1)

Caries susceptible rats fed condensed milk with or
without sucrose added show no tendency toward caries
development over

a period of 190 days even though

signs of malnutrition are evident.
2}

Susceptible strain rats fed a ration containing 79%
whole powdered milk remained caries-free for 160
days.

♦

BIBLIOGRAPHY

Hunt, H. R., Hoppert, C. A., and Erwin, W. G., Inheritance
of Susceptibility to Caries in Albino Rats, J. Dental Re­
search 23: 385 (19Ui)«
Hoppert, C. A., Webber, P. A», and. Canniff, T. L., the Pro­
duction of Dental Caries in Rats Fed an Adequate Diet. J.
Dental Research 12:161-173 (1932).
McCollum, E. V., Siranonds, N., Kinney, E. M«, and Grieves,
C. J., The Relation of Nutrition to Tooth Development and
Tooth Preservation. I. A Preliminary Study of Gross Maxil­
lary and Dental Defects in Tvro Hundred and Twenty Rats on
Defective and Deficient Diets. John Hopkins Hosp. Bull.
33:202-215 (1922).
Grieves, C. J., A Preliminary Study of Gross Maxillary and
Dental Defects in Three Hundred Rats on Defective and De­
ficient Diet. J. Arc. Dental Assoc. 9ih£>7-h9k (1922) a.
Bunting, R. W., The Experimental Production of Dental Caries
in Animals. Dental Cosmos 67:771-778 (1925).
Shibata, M., On the Experimental Dental Caries of Molars of
the White Rat. Shikwa Shimpo, 32: 1-7 (1929)j Japan J. Exp®
Med. 7:2U7-25l (1928-1929).
Shibata, M., Sugar and Teeth.
21U-223 (1930).

J. Nippon Dental Assoc. 23:

Kesel, R. G., What Do We Know About Dental Caries? (A criti­
cal review of recent investigations). J. Am. Dental Assoc.
19:903-917 (1 9 3 2 ).
Klein, H., and McCollum, E. V., A Preliminary Note, on the
Significance of the Phosphorus Intake in the Diet and Blood
Phosphorus Concentration, in the Experimental Production of
Caries-Immunity and Caries-Susceptibility in the Rat.
Science 7^:662-661) (1931).
Agnew, M. C., Agnew, R. G., and Tisdall, F. F., Experimental
Oral Lesions in Rats. J. Dental Research 12sl)U9-U50 (1932).

11. Johnston, M. M., Kaake, M. J., and Agnew, M. C., The
Relationship of Lactobacillus Acidophilus to Dental
Caries in Experimental Animals and in Human Beings.
J. Am. Dental Assoc. 20:1777-1781+ (1933).
12. Toverud, G.,Experimental Studies on the Physiological
and the Pathological Chemistry of Teeth with Special
Reference to the Influence of Calcium, Vitamins and
Parathyroid Glands. Oslo, Fabritius and Sinner, 1926.
Ili5 p.
13.

Knowlton, G. C., Relation of Diet to the Production of
Dental Caries in Your Rats* Proc. Soc. Exp. Biol. Med.,
27:757-758 (1929-1930).

lit• Krasnow, F., Biochemical Studies of Dental Caries:
Effects of Low Fluorine Diets on Rats. J. Dental
Research 12:523-533 (1932).
15.

Rosebury, T,, and Karshan, M., Studies in the Rat of
Susceptibility to Dental Caries. I. Bacteriological
and Nutritional Factors. J. Dental Research 11:121135 (1931) a.

16.

Lilly, C. A., Failures to Produce Experimental Dental
Caries in the White Rat with High Carbohydrate. Diet and
Bacillus Acidophilus or with Vitamin D Deficiency.
,T. Wntr-iti on 5?175-l8l (1932).

17.

Lilly, C. A., and Grace, J. D., Failure to produce
Dental Caries with High Carbohydrate, and Extremely
Low Fat Diets. Proc. Soc. Exp. Boil. Med. 30:176177 (1932-33)

18.

Hoppert, C. A., Webber, P. A., and Canniff, T. L.,
The Production of Dental Caries in Rats Fed an Adequate
Diet. Science 7U:77078 (1931).

19. Webber, P. A., The Effects of Certain Diets on the Teeth
of the Albino Rat with Special Reference to the Develop­
ment of Dental Caries. J. Tenn. Acad. Sci. 7:11+1-162
(1932).
20.

Klein, H., and McCollum, E. V., The Significance of FoodParticle Size in the Etiology of Macroscopic Dental Decay
in Rats. J. Dental Research 13:69-71 (1933).

21. Shelling, D. G., and Asher, D. E., Calcium and Phosphorus
Studies. VIII. Some Observations on the Incidence of
Caries-Like Lesions in the Rat. J. Dental Research 13:
363-378 (1933).
22. Rosebury, T., Karshan, M., and Foley, G., The Experimental
Production of Typical Dental Caries in Animals, and its
Value for the Study of Decay of Teeth in Man. J. Dental
Research 13:11*3-11*1* (1933) a.
23. Rosebury, T., Karshan, M., and Foley, G., Studies, in the
Rat, of Susceptibility to Dental Caries. III. The Experi­
mental Production of Typical Dental Fissure-Caries and
Other Lesions in Rats, and Preliminary Studies of Their
Etiology. J. Dental Research 13:379-398 (1933) b.
21*. Rosebury, T., Karshan, M., and Foley, G., Studies in the
Rat of Susceptibility to Dental Caries. IV. Further
Studies of the Etiology of Fissure Caries. J. Am. Dental
Assoc. 21:1999-1611 (193k) b.
29.

Rosebury, T., Karshan, M., and Foley, G., Studies in the
Rat of Susceptibility to Dental Caries: A Review of Four
Years of Research. J. Am. Dental Assoc. 22:98-113 (1939).

26.

Bibby, B. G., and Sedwick, H. J., Formation of Cavities in
Molar Teeth of Rats. J. Dental Research 13:1*29-1*1*1 (1933).

27.

Lilly, C. A., and Wiley, L., Relation Between the Physical
Character of Food and Dental Caries in Albino Rats- J. Nutri­
tion 7:1*63-1*72 (193k).

28.

King, J. D., Dietary Factors in the Production of Dental
Disease in Experimental Animals, with Special Reference to
the Rat. Part I. Dental Caries. Brit. Dental J. 99: 233210*5 309-316 (1939).

29.

McKay, F. G., and Black, G. V., An Investigation of Mottled
Teeth. D. Cosmos, 98:1*77, 781 and 891* (1916).

30.

Cheyne, V. D., Production of Graded Mottling in Molar Teeth
of Rats by Feeding of Potassium Fluoride. J. Dental Research
21:11*9-199 (191*2).

31.

Cox, G. J., Matuschak, M. C., Dixon, S. F., and Walker, W. E.,
Mottled Enamel in Rat Molars. Science 90:83 (1939).

32.

Armstrong, W. D», Influence of Fluorine on Teeth of Rats.
J. Dental Research 13s223 (1933)*

33* Armstrong, W. D., Review of the Dental Fluorosis Studies
at the University of Minnesota, Fluorine and Dental Health,
p. 5h-62. Washington, Am. Assoc. Advancement Sdi. 19l*2.
3l*. Arnold, F. A., Jr., and McClure, F. J., Observations on
Induced Caries in Rats. II. The Effect of Subcutaneous
Injections of Fluorides. J. Dental Research 20:239 (19i*l).
35.

Arnold,
Induced
taneous
1*57-1*63

F. A., Jr., and McClure, F. J., Observations on
Dental Caries in Rats. II. The Effect of Subcu­
Injection of Fluoride. J. Dental Research 20:
<19Ul).

36. McClure, F. J., Observations on Induced Dental Caries in
Rats. Ill Quantitative Relations of Effect of Fluorine
on Rat Caries, and Data Regarding Composition of Molar
and Incisor Teeth. J. Dental Research 20:238-239 (19l*l) a.
37.

Cox, G. J., Matuschak, M. C., Dixon, S. F., Dodds, M. L.,
and Walker, W. E., Experimental Dental Caries. IV. Fluo­
rine and its Relation to Dental Caries. J. Dental Research
18 :1*81- 1:90 ( 1939).

38.

Miller,B. F., Inhibition of Experimental Dental Caries in
the Rat by Fluoride and Iodoacetic Acid. Proc. Soc. Exp.
Biol. Med. 39:389-393 (1938).

39*

Gerould, C. H., Election Microscope Study of the Mechanism
of Fluorine Deposition in Teeth. J. Dental Research 21*:
223 (191*5).

1*0. Brown, A., and Tisdall, F. F., The Effect 01 Vitamins and
the Inorganic Elements on Growth and Resistance.to Disease
in Children. Ann. Internal. Med. 7231*2-352 (1933).
1*1.

Day, C.D. M., Daggs, R. G., and Sedwick, H. J., Influence
of High-Sugar Diets Upon Teeth of White Rats. J. Dental
Research Il*:2l5-2l6 (193U).

1*2.

Day, C. D. M., Daggs, R. G., and Sedwick, H. J., High
Sugar Diets and Dental Caries in the White Rat. J. Am.
Dental Assoc. 22:913-925 (1935).

1*3«

Cox, G. J., Nutrition and Dental Caries in Rats. Abstracts,
Sub-Sect. Dentistry, Am. Assoc. Advancement Sci* p. 2 (1938).