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DENTAL CARIES 0F RATS PRODUCED
BY ACIDOGENID ORGANISMS

THESIS FOR THE DEGREE OF M. S.

John Lincoln Etchells
1932

 

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DENTAL CARIES OF RATS PRODUCED BY ACIDOGENIC ORGANISMS

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DENTAL CARIES OF ms PRODUCED BY ACIDOGmIC ORCELNISIB

THESIS

Submitted to the Faculty of the Michigan State College
in partial fulfillment of the requirements for the

Degree of Master of Science

by

John Lincoln.Etchells
:7
1952

i 3.6

THESS

 

ACKNOWLEDGMENT

I wish to acknowledge my indebtedness to
Doctors E. D. Devereux and C. A. Heppert for their
interest shown throughout this investigation, and

for the helpful advice freely given.

95070

TABLE OF CONTENTS

Title
Acknowledgment
I. Introduction
II. Review of Literature
III. Experimental
A. Bacterial study of foods
B. Bacterial study of carious teeth

C. Production of dental caries in.rats with
acidogenic organisms

D. Fermentation studies on organisms occurring
naturally in.rat food and those isolated
from.carious teeth

E. An attempt to demonstrate agglutinins in
rats on experiment

IV. Discussion
V. sumary

VI. 'Literature Cited

I. Introduction

The subject of dental caries has been studied
in great detail since 1867 when Leber and Rottunstein (1)
wrote a most interesting book on the subject. They
presented a theory of dental caries which does:not
vary in great detail from.the conceptions of the in-
vestigators of the present day, who recognize the role
of bacteria.in relation to dental decay. However,
Miller (2) not only confirmed the earlier investigations
as to the action of organic acids upon the inorganic
constituents of the teeth, but showed by experiment
the action of these acids upon their structure. For
the following half century, work on cause of dental
decay was carried on under the stimulus of Miller's (2)
theory.

Recent research on dental caries has, in the
greater part, been confined to the part played by diet
and nutrition. The present day investigators, while
recOgnizing Miller's theory, find it inadequate in
some respects and would place the most emphasis upon
the dietary deficiencies, rather than acknowledge the
role of acidogenic bacteria.

HOppert et. a1. (5) showed that dental caries
could be produced in rats fed on an adequate diet by
retention of coarse food. Using this work as a

foundation, this study demonstrates the bacteriological

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-2-

role of acidogenic organisms, by using such bacteria
to produce dental caries in rats, a procedure which

heretofore has met with little or no success.

II. Review of Literature.

Although a review of the etiological factors of
dental caries has been presented by Banks (4),

Bunting (5), and Marshall (6), it appears necessary
that investigation pertaining to the bacteriology of
this disease be reviewed again as it is of primary
importance to the work presented by the writer.

In 1883 Miller (7) first recognized the relation-
ship between bacteria and.dental caries. He was of
the opinion that although bacteria were not the sole
cause of dental caries, there was no case of dental
caries in which they did not play an important part.
Due to a lack of suitable culture media he was unable
to give complete discriptions of'the bacteria he
studied.

Hartzell and Henrici (8) in 1917 reported that
mouth streptococci are the only true parasitic organisms
of the normal, characteristic mouth flora. They state
definitely that these bacteria were the cause of dental
caries as well as a number of other dental diseases.

In 1920 Kahnert (9) made a study of dental caries
in the horse. He concluded that as in human beings,
dental caries is not caused by any one specific
organism. He stressed the importance of acid-forming
and proteolytic organisms. .

Rodriguez (10) in 1922 classified a high acid-

producing type of bacteria as types I and II, on the

basis oflnorphology, and found them.constantly in
the deep portions of the foci of active dental caries.

McIntosh, Lazarus-Barlow and James (11) in 1925
produced artificial caries by placing teeth in broth
inoculated with acidogenic organisms. After a pro-
longed period the teeth showed erosion of the enamel,
penetration of the dentinal tubules, almost identical
to natural caries. They were, however, unable to
produce dental caries in vivo by feeding acidogenic
bacteria. In their study of fifty carious teeth, two
types of organisms similar to Lactobacillus acidophilus
were found. One organism occurred in 88 per cent of'
the teeth examined, and the other in 42 per cent.

They preposed the name Bacillus acidophilus odontolyticus,
I and II.

Howe (12) in 1924 was able to produce dental
diseases in.monkeys by feeding diets solely deficient
in.vitamin "C", but he reports that earlier work on
production of dental caries in animals by acid-forming
organisms was unsuccessful.

Sierakowski and Zajdel (15) in 1925 confirmed
the work of mcIntosh et. a1. regarding the role of
pg; acidophilus in dental caries. They isolated this

 

organism from 80 per cent of the dental caries
examined. Two types were found, long slender rods,

and short thick rods. Both grew feebly in liquid media.

They noted that the best growth occurred in glucose

-5-

broth. Pure cultures of these organisms caused
typical caries in a tooth in a test tube in three
months.

Bunting and Palmerlee (14) further confirmed
these findings when in 1925 they found an acidogenic
and aciduric type organismwwhich appeared to be
I: acidgphilus in practically every lesion of active
dental caries.

Schlirf (15) who made a bacteriological investi-
gation of dental caries in Germany in 1926, stated
that the decalcification of the teeth was due to the
production of acid produced by bacterial metabolism.
He noted large numbers of acid-forming rods in carious
dentine. These conclusions as to decalcification were
discussed most clearly by Miller (2) in 1883.

Rosheny, Linton and Buchbinder (16) in 1929
studied the aciduric organisms and L; acidophilus in
dental decay. They could see no differentiation
between these two types of organisms. Out of 21
strains of aciduric organisms isolated from.teeth no
differences could be detected between the two groups
in the morphology and bioéchemical study. There was
no clear distinction in the serological reactions, as
there was marked cross agglutination.

In contradiction to the investigators that report

finding L; acidOphilus in practically every lesion,

 

Morishita (17) reported that from.105 strains of

-5-
aciduric organisms isolated from dental caries only
7 bore a close resemblance to L; acidophilus (more).

.In 1929 Bodecker (18) proposed a theory as to
the cause of dental caries. He maintained that
fermentation of carbohydrates formed lactic acid,
which attacked mineral constituents, while the organic
substance is destroyed by another type of bacteria.
Thus a cavity is formed. This theory was propounded
almost identically by Miller (2) in 1885 and by others
later.

Morishita (19) in 1929 found that high acid
tolerating organisms were found in constant occurrence
in tooth enamel in the process of decay. Relatively
few were noted in non-carious teeth. He could produce
decalcification in vitro but not in vivo.

Marshall (6) in review of the etiology of dental
caries states "An historical rebume of the etiology
of dental caries presents at least one interesting
fact; namely, more has been written and less known

of this disease than.any other dental lesion".

.-7-

III. Experimental.
A. Bacterial study of rat foods
Procedure

One gram each of rice, powdered milk, and corn
was taken from.etock and.after making proper dilutions
was plated on yeast extract agar*. The typical
colonies from each food were noted as to morpholOgy,
and then picked into litmus milk to find the acid re-
action.

Results

The types of organisms naturally occurring on the
grains studied, that were used for food for rats, had
a close relationship to the types isolated from.the'
teeth. The production of acid by the organisms from
the food would probably'be sufficient if once establish-
ed in the food-impacted teeth to give rise to cavities.

It must be noted that while a total of 15 acid-
forming organisms were isolated from.the foods studied,
there were also 16 proteolytic organisms noted. This
fact may have a direct bearing on the more advanced
stages of dental caries, where the decomposition has

reached the bone tissue. Miller recognized the

*Formula for yeast agar:

Peptone ----------- 5, 0 grams
Peptonized milk -------- . 10.0 n
Dextrose --------------- 5.0 n
Yeast extract ---------- 5.0 "
Agar ------------------- 15.0 "

Water ------------------ 1000.0 0.0.

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-8-

proteolytic enzymes, as his theory of decay was divided
into two parts, first, fermentation of carbohydrates
to form.organic acids and secondly, action of proteo-
lytic enzymes on the protein constituent of the teeth.
0f the 12 organisms isolated from.the rice, six
were acid producers, which formed a typical anooth
curd in 48 hours while one produced acid indicated by
litmus change in 48 hours, and formed curd after several
days.
In the case of the powdered milk, being a labora-
tory product, the acid formers were not as numerous.
0f the 11 organisms isolated, two formed smooth curds,
and one formed acid in 48 hours incubation at 57°C.
in litmus milk.
From.the ll organisms isolated from.ground corn,

five were found to produce smooth curd in litmus milk.

-9-

B. Bacterial study of carious teeth.
Procedure

Organisms associated with dental lesions were
isolated from rats (old animals with pronounced caries)
by etherizing them, removing the jaw'bone, and with a
sterile, straight needle digging into the foci of in-
fection and smearing direct on yeast extract agar plates.
These plates were incubated for 48 hours at 57°C. The
typical organisms usually appeared in pure culture and
were then studied as to morphology and acidogenic
properties. .

Results

From.the total of 12 rats, (old females) with
caries well developed, 48 organisms were isolated. Of
this number 50 were producers of acid curd in litmus
milk.

Organisms from rats,Nos. 5 to 12, were obtained
by smearing direct from the carious area with straight
platinum needle. The preceeding organisms, those
from rats Nos. 1 to 5, were isolated by dilution
method made from.material taken from the tooth. The
former method proved superior, as the needle reached
.the focus of the carious lesion, and hence limited the
organisms obtained to those having direct association
with decay.

From the plates that were streaked directly on

yeast extract agar, the typical colonies found were

-10..

repeatedly noted. They were (1) streaks of small
white, glistening colonies, gram positive cocci,

and (2) streaks of veily, grey filamentous colonies
of large, plump gram positive rods, resembling

.9; acidgphilus. These two organisms always pre-
dominated on the smeared plates and many times
occurred in pure culture. They were vigorous acid
formers and it was interesting to note that the same
organisms were observed on ten of the direct smears
made from human caries.

The coccus forms always appeared as small, round,
white, glistening colonies which would be lifted off
with a needle. They readily fermented the seven
diagnostic sugars for L; acidophilus and in 48 hours
incubation produced a pH of 4.6 in broth.

The L; acidophilus colonies occurred in three,

 

more or less typical forms, (1) regular, rough, fuzzy,
filamentous type (2) more compact, rough, irregular
edge type (5) round, irregular colony with projecting,

fuzzy filaments.

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-13-

The last four human strains (Chart II) obtained
from extracted carious teeth, remained in the R.S.
state when transferred daily in.broth, however, when
cultured on two per cent dextrose chicken infusion
agar and allowed to grow at room.temperature for three
weeks, typical smooth L; acidOphilus colonies appeared,
and upon staining revealed short bi-polar rods. If
the smooth colony was transferred into broth,it would
revert to the original R.S. stage. Time did not permit
a thorough study of this behavior, though it was repeat-

ed three successive times.

-14-

C. Production of dental caries with acidogenic organisms
Procedure
Source of cultures.

1. R20 - R. I:,acidophilus, oral strain, isolated

 

from old rat (female) with extensive caries.‘

2. K-RS - R.S. or rough variant L; acidophilus,
isolated from a student having typical dental caries.

5. K-l - Cocco-bacillus, isolated from a student,
having typical dental caries.

4. F-l - Coccus form.of fowl origin. Isolated
from a fowl having an impacted beak with extensive
fermentation so that the bill had been partially dis-
integrated. This organism appeared in pure culture,
upon streaking on yeast extract agar from the infected
area.

These organisms were chosen.because of their wide-
ly separated sources, and inaamuch as they were known
to be directly related to dental decay.

The eXperiment was based on the fact that rats
although fed upon an adequate diet, when food impactions
can be made by use of coarse rice or corn, will contract
dental caries.

*These organisms were first smeared directly upon yeast
extract agar with a straight needle. They were then
picked into yeast extract broth, and after 24 hours
incubation at 57°C. were streaked with a leap needle on
yeast extract agar slate and incubated at 57°C. for 24
hours. After picking into yeast extract broth for the

second time and incubating they were considered ready
to be used.

-15...

Hence by use of acidogenic cultures isolated from
dental caries, when placed in such an environment will
reproduce a typical case of dental caries as observed
so often in nature.

ExPerimental set-up
Cage No. 1 control - sterile diet - no organism
Cage No. culture R20 + sterile coarse ration
Cage No. culture K-RS + sterile coarse ration
Cage No. culture F-l + sterile coarse ration

impaction control - unsterilized coarse (corn or rice)

2
5

Cage No. 4 culture K-l + sterile coarse ration
5
Cage No. 6
7

Cage No. impaction control - unsterilized fine (corn or rice)
2 The selection of a proper diet that was suitable
for such an experiment involved much time and difficulty.
inasmuch as each experimental procedure took a period
of eight weeks. The diet finally chosen was one that
was adequate for growth, retained its characteristics
upon sterilization and was palatable to the rat. The
formula for the ration in percentages by weight was as

follows: Alfalfa 10, corn 65, oilmeal l5, yeast 5,

casein 5, sodium chloride 1, and calcium carbonate 1.
The ration, after being thoroughly mixed, was

placed in suitable containers, plugged with cotton

and autoclaved for 50 minutes at 15 pounds pressure.

A control can was plated for bacterial growth to insure

sterility. After being sterilized the food was broken

up with a sterile glass rod.

-16-

The organisms were added to the rations daily,
one c.c. of a 24 hour broth culture added by means
of a sterile pipette and mixed. Each day a complete
set of rations were made. This was done to insure
an excess of the culture, and to control the micro-
flora of the mouth.

The animals on the experiment were isolated and
daily the animals and cages were exposed to ultra-violet
light treatment to avoid outside contamination.

After a period of eight to ten weeks the animals
were etherized, the jaws removed and streak plates
made from carious areas of the teeth upon yeast
extract agar (pH 7.o)*. After incubation the plates
were ready for identification of organisms.

The stock cultures were identified according to
the following:

1. characteristics of colonies
2. staining morphology
5. sugar reactions

4. litmus milk reactions

*The teeth specimens, after culturing were washed and
dried and reserved for further study.

-17-

Results.

This experiment was performed to produce dental
caries by controlling the micro-flora of the mouth,
by use of acidogenic bacteria. These organisms were
inoculated into sterile rations containing coarse corn
or rice to cause retention of food. This impaction
of food resulted in carbohydrate fermentation.by the
acidogenic organisms, which in turn disintegrated the
dental structure.

The experimental work was retarded considerably
at the beginning until a ration containing coarsely
ground grain could be selected that would upon auto-
claving remain palatable to the rats and also retain
its physical characteristics and be adequate for growth..

After two preliminary runs of eight weeks each,
coarse corn was found to be the ideal grain for imp
paction. This also withstood autoclaving without
change of hardness. These investigations on corn
revealed that La acidophilus, which is a delicate
organism to grow and requires an enriched medium,

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The sugar reactions obtained in the identifi-
cation of cultures isolated from the caries produced
in the rats, were relatively inconsistent, and it
must be pointed out that sugar reactions can not be
used as diagnostic agents for delicate organisms such
as'L; acidOphilus. Duplicate sugar determinations
made on this and similar strains gave varied results.

The isolation and identification of stock
cultures was based on morphology, cultural character-
istics, pH changes and litmus milk reactions. As to
the use of serological reactions authors differ in
their opinions. Hadley, Bunting and Delves (20) report'
cross-agglutination of "S" antigen by "R" serum _
through a dilution of 1 to 1,280 and the "R" antigen
was completely agglutinated by the "S" serum through
a dilution of l to 5,120. In contradiction to these
results Upton and Kepeloff (21) state that pure line
"R" and "S" strainsappear to be antigenically
distinct. They demonstrated also that "R" forms of
.L; acidophilus and L; bulgaricus could not be_
distinguished.

Thus, with the serological question unsettled
it can not be taken too strongly as an index of
identification. Reliance should be placed on
cultural and morphological characteristics, which
were adhered to in the identification of the cultures

used in this experiment.

-22-

From the chart it appears that R20, KA1 and F-l
were identified as the cause of the carious lesions
in their respective animals, leaving.K-RS as the only
questionable organism. Although the cultural and.
morphological characteristics of the organism isolated
from the carious teeth, and assumed to be K-RS coincided
to a fair degree of accuracy to the characteristics
of the stock culture the organism did not appear as
numerous on the plate of the direct smear from.the
cavity as R20, K-l and F-l.

LL_acidophilus was not observed on the direct
smears from the carious areas of the teeth of the
animals receiving the cultures. There was an exception
to this in the case of R20 which was a rough Ea
acidophilus used on animals in cage No. 2. The
absence of rough La acidophilus on the other plates
demonstrated that the microflora, of the mouths of
the experimental animals, were adequately controlled.
In cage No. 6 receiving coarse corn,(not.sterile)
the organism isolated from.the caries of both
experimental rats was identified as L; acidophilus.

In cage No. 7.2; acidophilus was also observed, but
due to the fine corn no impaction resulted, consequent-

ly no fermentation or caries developed.

D. Fermentation studies on organisms occurring
naturally in rat food, and those isolated

from carious teeth.

Procedure

One gram samples were taken from.etock supply of
corn, rice and powdered milk. Ten c.c. amounts of
sterile water were added to each one of the tubes,
and after incubation for 48 hours at 57°C. 5 c.c. of
the fermented material was titrated with N/20 NaOH.

For fermentation of corn.by organisms isolated
from.denta1 caries, one gram.sanples of each were
taken and autoclaved for 50 minutes at 15 pounds
pressure. Ten c.c. amounts of sterile water were
added and after 48 hours incubation at 57°C. 5 c.c.
portions of the fermented material were titrated with
N/20 NaOH.

For fermentation of sugars by organisms isolated
from dental caries the following procedure was
observed. The diagnostic sugars were inoculated with
a 100p from 24 hour broth cultures then incubated

for 48 hours at 57°C. and recorded.

.24-

Chart V. Unautoclaved stock foods with naturally
occurring organisms.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

—T I I
Corn 'c.c. of N/20'c.c. of material' Per cent normal
samples'NaOH used ' titrated ' acid present
I I I
T T *I
No. l ' 1.2 ' l ' 6.0
No. 2 ' 1.15 ' 1 ' 5.75
T I ‘I
No. 3 ' 3.55 ' 5 ' 5.58
r I —r
No. 4 ' 1.5 ' 5 ' 1.5
T T T
No. 5 ' 0.60 ' l ' 5.0
I I I
No. 6 ' 0.90 ' l ' 4.5
[—— .
I —T I
Rice ' ' '
samples' ' '
T I I
NC. 1 ' 008 " 3 ' 1053
, T Ir' _T
No. 2 ' 2.5 ' 5 ' 2.5
T T T
No. 5 ' 2.2 ' 5 ' 2.2
I I T
No. 4 ' 139 ' 5 ' ~#;.9
I I I
Powdered I I
milk ' ' I
samples' ' I
I I I
EQ:_1 ' 2‘75. ' 5 ' 2.75
I I I
nil-i ' L50 ' 5 I 5.50
I I I
mnl_a ' age I 5 I 2.20
I I I
HQ g I 2.8 I 5 I 2.80

 

-25-

Chart VI. Autoclaved corn.meal + sterile salt solution
+ organisms isolated from.dental caries.

 

 

 

 

 

 

I “T I
0rganism.used' c.c. of N/20' c.c. of ' Per cent normal
' NaOH used ' material ' acid present
' - ' titrated '
I I I
I I I
R20 " R0110 ' 1.25 ' 1 ' 6.25
acidophilus ' ' '
I— r I
R12 " Rollo ' 0095 ' 1 ' 4075
acidophilus ' ' '
I T I
K‘l " human ' 00 55 ' 1 ' 2050
cocco- ' ' '
bacillus ' ' '
T I— T
K-RS - human ' 0.60 ' l ' 5.00
R.S.L.acid- ' ' '
ephilus ' ' '
r I I
F-l - coccus ' 0.65 ' 1 ' 5.25
I I I

from fowl

Chart VII. Sugar reactions of organisms isolated from

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

raffinose

carious teeth.
I I
Organism, ' Source ' _§ugars*
' '1'2'5'4'5'6'7':
F IIII_ITTIT
l-R12 ' rat ' +' +' +' +' +' +' -
_T IIIITII
l-R2 ' rat ' +' +' -' -' -' -' -
j VVT‘TI'TTI
1-R21 ' rat ' +' +' -' -' +' -' -
T— TTTIIII
H-B ' human ' +' +' -' -' -' -' -
I IITTIII
H-A I human I+I +I__I _I_I _I_
T I FTTT I I
H-D ' human ' +' +' -' -' -' -' -
' TTI'TTI I
H-C ' human '+'+' +'-'+'+'-
I I IIfiI I II
L.A. S 'stock culture ' +' +' -'.—' -' -' -
' TTITTT'
+
L.A. R 'stock culture ' -' 1' -' -' -' -' -
F IIIrIfI
R20 ' rat ' +' +' -' -' +' -' -
r IIIITI]
319 ' rat ' +' +' -' -' t' -' -
' I ' TTTFI
F-l ' fowl ' +' +' +' +' +' +' t
*1. dextrose
2. levulose
5. d-galactose
4. mannose
5. maltose
6. lactose

The acid production of these organisms, naturally
occurring in corn and those isolated from caries was
very high. Artificial caries in vitro have been
produced by investigators by use of one per cent lactic
acid. Hence, with acidogenic organisms producing
acid from.2 to 5 per cent in corn emulsion, it would
not be unreasonable to believe that carious lesions
could be readily produced with the retention of the
corn particles. Thus the two important factors in
dental decay are: (l) The presence of the acidogenic
bacteria as demonstrated by this exPeriment, and (2)
the retention of the corn particles as demonstrated
by control cage No. 6 in which the natural occurring

organisms in the unautoclaved diet were used.

-28-
E. An attempt to demonstrate agglutinins in rats
on experiment. -
Procedure

It was assumed that in the case of an extensive-
ly decayed tooth, in which the cavity proceeded to
the bone tissue (which is often the case) that the
organisms might be introduced into the blood stream,
and give rise to agglutinins. This being the
supposition the following technique was observed.

The rats,at the time they were examined for
dental caries, were etherized and three c.c. of blood
was drawn from.the heart with a sterile syringe.

The blood was allowed to clot, and after standing
over night in the refrigerator it was centrifuged
and the serum.drawn off.

Antigens were prepared by growing the test
organisms in yeast extract broth for 18 hours at 57°C.
They were then centrifuged and washed with phenolized
salt solution, resuspended and adjusted to the preper
turbidity standard. The agglutination tests were

conducted in the usual macroscOpic manner.

-29-
Results*
Chart VII. Agglutination reactions of stock culture

antigens and serum from.rats on
experiment. (Second run).

 

 

 

 

 

 

 

 

 

 

userumr T T I r r ‘I I r I *fi'
Antigen' of 'l-l'1-2'1-4'1-8'1-16'1-52'1-64il-128'l-256'control
Icage I . I I I I I I I I I
r T I I” T r I I I I I
R20 IN0.1 I _ I _ I _ I _ I _ I _ I _ I _ I _ I _

I I r I I r ‘ I I "I I
R20 'No.2 ' + ' + ' + ' + ' + ' + ' + ' + ' + ' -

T I I r w I r T r r I
K-RS 'No.5 ' + ' + ' P ' T ' - ' - ' - ' - ' - ' -

I I I I w I r T“ T I I
K-l INO.4 I + I P I T I _ I __ I _ I _ I _ I _ I _

I I Ijfi r I r I T I i.
F-l 'NOes I P ' P ' T ' - ' - ' '0 ' - ' I- ' -I ' .-
L T FI‘I— I r' I I “r I I
R20 'No.6'+'+'+ +'+ '+ '+ '+ ' + ' -

I r r r i f r T I T 7
R20 IN0.7 I _ I _ I _ I - I _ I _ I _ 'I - I _ I _
Note; agglutination

partial agglutination
trace of agglutination
no agglutination

III-3’64-
IIIIIIII

*Results on the first run of rats (on production
of dental caries) showed positive agglutination
through the first three dilutions of K-l antigen,
by the serum of the animal being fed sterile diet
+.K-l organism. This animal had well develOped
caries.

IV. Discussion

It is regretted that the bacteriological studies
on dental caries were limited since time did not
permit a more thorough investigation. While one
successful run on production of dental caries by the
use of acidogenic organisms, did not constitute
definite proof, however, it did give a satisfactory
technic which was imperative in such a study.

According to these studies, it was evident that
acidogenic bacteria were present in great numbers on
the normal food of the rats, and that with these
organisms and food retention, decay is inevitable.
If this is proven to take place (in animals fed
adequate diet) as shown by control animals in cage
No. 6, then it is highly improbable that dental
caries can‘be attributed solely to dietary deficiencies.

Thus these data presented uphold and strengthen
the bacteriological theory (Miller) of decay. The
use of acidOgenic bacteria to control the micro-flora
of the oral cavity and to isolate those cultures
from the resulting cavities (after an eight week period)
certainly favors the bacteriological theory and leaves
little or'no ground for those investigators who are
prone to disregard the role of bacteria in dental
decay. It is not the writer's wish to engage in
controversy over the theories existing as to the

cause of dental caries, but it is h0ped that these

-51..

data will show the role of bacteria in dental decay.

The bacteriology of dental caries has been worked on

for the last fifty years, and is not to be wholly
supplanted by new studies, those of dietary deficiencies
which attempt to explain more conclusively the

mechanism of dental caries.

-n—gi r

4‘ arc-mu..- .. u.-
\

4.

V. Summary
Acidogenic organisms were found in rat food.

L. acidophilus was isolated from approximately

 

60 per cent of the dental caries of rats examined.
Proteolytic organisms were isolated from caries
of rats.

Dental caries in rats was produced by use of
acidogenic‘organisms.

Fermentation of rat food by naturally occurring
organisms, and those isolated from carious teeth
of rats, resulted in high acid production.
Production of agglutinins in rats fed acidogenic

organisms was inconsistent.

‘m’ Anna-mug- 2 “h— .1 ‘_'\m.- h." n‘ l s
. .‘h.

4.

8.

10.

ll.

12.

7-!

-03-

VI. Literature Cited.

Leber and Rottenstein: 'Untersuchungen uber die
Karies der Zahn, Berlin: Hirschfeld.

Miller, W. D. Tr. IV. Internet. Cong. 1:257.

HOppert, C. A., Webber, P. A. and Canniff, T. L.
The production of dental caries in rats fed an
adequate diet. Jour. Dental Research, 12:161-170.
1932.

Banks, M. T. The role of diet in the cause,
prevention and cure of dental diseases. Jour.
Nutr., 5:455-451, 1951. _

Bunting, R. W. A review of recent researches
on dental caries. Jour. Amer. Dental Assoc.,
18:785-806,'l951.

Marshall, J. R.. The etiology of dental caries.
Phys. Review, 4:564, 1924. -

Miller, W. D. The agency of microorganisms in
the decay of human teeth. Dental Cosmos, 25:1,
1883.

Hartzell, T. B. and Henrici, A. T. Mouth strepto-
cocci and dental caries. Abst. of Bact., 1:272,
1917. . .

Kahnert, B. Etiology of dental caries in the
normal horse. Abst. of Bact., 4:242, 1920.

Rodriguez, G. E. Studies on the specific
bacteriolqu of dental caries. Abst. of Bact.,
7:28, 1922.

McIntosh, J., Lazarus-Barlow, P., and James, W. W.
Investigations into etiology of dental caries.
Abst. of Bact., 7:442, 1925.

,Howe, P. R. Studies of dental disorders following
eXperimental feeding with monkeys. Jour. Am.
Dental Assoc., 11:1924.

Sierakowski, S. and Zajdel, R. Bacteria causing
dental caries. Abst. of Bact., 9:164, 1925.

Bunting, R. W. and Parmerlee, Faith. Role of
B. acidophilus in dental caries. Jour. Am.
Dental Assoc., 12:581, 1925.

5—17.” .. I

15.

16.

17.

18.

19.

20.

21.

Schlirf, K. Bacteriological investigation of
dental caries. Biol. Abst., 1:898, 1927.

Rosheny, T., Linton, R. W., Buckbinder, L.
Study of dental aciduric organisms and L.
acidOphilus. Jour. of Bact., 18:395, 1929.

horishita, T. Further studies on certain
aciduric organisms of dental and salivary
origin. Jour. Bact., 17:7, 1929.

Bodecker, C. F. A new theory of the cause of
dental caries. A. J. P. H. A., 19:1104, 1929.

Morishita, T. Studies on dental caries with
specific reference to aciduric organisms
associated with this process. Jour. Bact.,
18:180, 1929.

Hadley, F. P., Bunting, R. W. and Delres, E. A.
Recognition of B. acidOphilus associated with
dental caries. Jour. Amer. Dental Assoc.,
17:2041-2058, 1930.

Upton,.M. F. and Kopeloff, N. Agglutination
and dissociation studies with lactobacilli.
Jour. Bact., 23:455, 1932.

“L In.)

 

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