Effects of Certain Diets on the Teeth of
he Albino R at W ith Special Reference
to the Development of Dental Caries

By PERRY A. WEBBER

THESIS

Subm itted in P artial Fulfillment of the Requirements for
th e Degree of Doctor of Philosophy a t
Michigan State College

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R e p rin te d f ro m the

J ournal of t h e T ennessee A cademy of S cience

Vol. V I I . No. 3, 1932

JOURNAL
cf the

T en nessee A cadem y o f Science
Vol. V II

JU L Y , 1932

No. 3

T H E E F F E C T S OF CERTAIN D IE TS ON T H E
T E E T H OF T H E ALBINO RAT W I T H SP ECIAL
R E F E R E N C E TO T H E D E V E L O P M E N T
OF D E N T A L CARIES1
NASHVILLE
P

PERRY A. WEBBER
AGRIC ULTURAL NORMAL

urpose a n d

A

im

of

T

h is

INSTITU TE

S tudy

T he problem of tooth hygiene, structure, decay, resistance to decay,
its prevention, etc., has been one which has engrossed the attention
of w orkers in various fields for m any years. T he dentist, the bac­
teriologist, the n utritionist, the pediatrician, the biochemist, and
others have each made contributions to this interesting and im portant
subject.
I t was the purpose of this study to find the effects of certain diets
on the developm ent of teeth of the albino rat, and if possible to
d raw conclusions th erefro m which m ight throw some light on the
general problem of tooth hygiene, and the effects of diet on teeth and
tooth preservation, as it m ay apply to the hum an species.
H

is t o r ic a l

I N C I D E N C E OF CARIES I N A N C I E N T T IM E S

T h a t caries is not a m odern disease is adequately shown by studies
in paleopathology and paleo-odontologv. A few references will show
how w idespread this disease has been in historic and prehistoric times.
I quote from R uffer, the fo llo w in g : “ Carious hum an teefh from
ancient rem ains have been discovered in so m any places th a t it is
legitim ate to doubt w hether there ever was ati epoch when the hum an
species was not cursed by toothache.”
E NGLAND

“ T he population of E ngland has certainly suffered from it (tooth­
ache) fo r thousands of years.” S ixty-nine skulls from the W iltshire
tum uli from the stone age showed two carious teeth, fti N orthern
E ngland, in fo rty -fo u r skulls, nine carious teeth were found. Six
' R e a d bef ore the Tennessee A cad e m y of Science at the N as h v ille meeting,
N o vem b er 27. 193 1.
—

141—

142

Journal o f the Tennessee A c a d e m y o f Science

cario u s te e th w ere fo u n d in th irty -tw o sk u lls o f th e b ro n z e age. T h e
incidence o f caries am o n g th e R o m a n s in E n g la n d based on th e e x ­
am in a tio n of 133 sk u lls sh ow ed 2 8 .6 7 % c a rio u s. S e v e n ty -six skulls
of th e A n g lo -S a x o n s h ad fifte e n cario u s tee th . T h e fre q u e n c y of
d en tal caries a t p re s e n t in th e B ritis h Isle s h as been v a rio u sly esti­
m ated fro m 8 6 -9 8 % .
EGYPT

“ F ro m th e e a rlie st to p re s e n t tim es, c aries h a s a tta c k e d h u m a n teeth
in N u b ia an d U p p e r a n d L o w e r E g y p t. B o th in N u b ia a n d E g y p t
th e o rd in a ry fo rm o f caries is e x c eed in g ly ra re in p re d y n a stic and
p ro to d y n a stic people, an d a m o n g th e p o o re r classes it n e v e r becam e
com m on u n til m o d e rn tim es. D e n ta l c aries becam e com m on a s soon
as people learn ed lu x u ry . In th e c e m e te ry o f th e tim e of th e A n cien t
E m p ire e x c a v a ted by th e H e a r s t E x p e d itio n a t th e G iza p y ra m id s,
m o re th a n 500 sk eleto n s o f a ris to c ra ts o f th e tim e o f th e p y ra m id
b u ild e rs w ere b ro u g h t to light, a n d in th ese bodies I fo u n d th a t ta r ta r
fo rm a tio n s, d en tal caries, a n d a lv e o la r ab scesses w ere a t least as co m ­
m on as th e y a re in m o d e rn E u ro p e to d ay .
“ A t su b se q u e n t p e rio d s in E g y p tia n h is to ry th e sam e th in g is
tru e — p rev alen ce of caries am o n g th e w e a lth y classes a n d relativ e
im m u n ity am o n g people w ho lived on a c o arse, unco o k ed d ie t.”
R u f f e r ’s a rtic le is acco m p an ied by m an y p la te s p ro v in g th e valid ity
of th e above sta te m e n ts.
In v e stig a tio n s in th e N ew W o rld go to show th a t d e n ta l caries w as
also p re v a le n t am o n g its in h a b ita n ts.
SO U TH A M ERICA

H o o d ie ex am in ed sk u lls of P re -C o lu m b ia n P e ru v ia n s a t th e S a n
D iego m u se u m an d fo u n d 6 w ith d e n ta l caries. M a c C u rd y m ad e a
stu d y o f th e P re -C o lu m b ia n P e ru v ia n s o f th e H ig h la n d s an d has
listed th e incidence o f c aries o f th e in h a b ita n ts.
NORTH

A M ERICA

T h e stu d y by R a y m o n d C. B e n tz e n is ty p ical of sev e ra l th a t have
been m ad e on d en tal d iseases am o n g th e In d ia n s o f N o r th A m erica.
T h e te e th a n d ja w s fro m a series of sk e le to n s u n e a rth e d by th e J e n k ’s
E x p e d itio n s show th a t th e M im b re s p eople p o ssessed v e ry h a rd teeth,
d u e p e rh a p s to the h ig h calcium co n te n t of th e ir food. B e n tzen says
th a t th e ir d iet co n siste d o f co arse, n a tu ra l fo o d s w hich necessitated
th o ro u g h chew ing, th u s g iv in g p le n ty o f e x e rc ise to th e ja w s. P r o ­
lon g ed m a stic a tio n p ro d u c e d larg e, h eav y ja w s g iv in g p le n ty of room
f o r th e te e th to e ru p t p ro p e rly , b u t th e te e th w e re ra p id ly w o rn dow n
d u e to th e g r itty m a te ria l in th e ir fo o d , a n d so m etim es lo st th ro u g h
ex p o su re of th e p u lp an d to apical ab scesses.
T h e ir te e th w ere fa irly im m u n e to c aries th ro u g h th e enam el, b u t
th e calc u la r d e p o sits cau sed recessio n o f g u m s p e rm ittin g co n ta c t of
a c id -fo rm in g b a c te ria a t th e c e m e n to -e n am el ju n c tio n w h e re 8 0 %

Diet and Dental Caries in the Rat

143

of the caries started. N otw ithstanding the fact th at the M im bres
people observed no oral hygiene or care of the teeth, they w ere better
fitted fo r thorough m astication of food than are the Am ericans of
today.
H A W A II

A study published in 1927 shows th at caries was a prevalent disease
am ong the ancient H aw aiians.
T he above references and quotations are sufficient to prove that
caries is not a m odern disease.
MODERN STUDIES AS TO T H E I N C I D E N C E OE D E N T A g CARIES

Leigh exam ined the crania of 324 m odern E squim aux from G reen­
land, Cum berland Sound, Po in t B arrow , St. Law rence Island, St.
M ichael, Alaska, and the Siberian Coast, and found an incidence of
but 1 % caries.
Suk com pared the eruption and decay of perm anent teeth of
whites and negroes. T his rep o rt is of observations made on 1,008
sub-adult Zulus from all p arts of N atal and Zululand. O f these 492
were males and 516 females, of different ages. T he observations on
w hites were m ade on the children of several norm al schools, on
students of colleges, and on apprentices in different trades, in Prague,
Bohemia. R esults of observations show that white children have
m ore than ten times as m any decayed teeth as the negroes. A t the
age of eighteen years, there are only 10-15% of individuals am ong
whites in large cities w ith a faultless set of teeth, while among Zulus
85-94% w ere found.
Campbell reports studies on 630 m odern A ustralian aboriginal
skulls of all ages. T hirty-seven of these were of children under
twelve years of age, and showed no caries present. M odern in­
h abitants of Adelaide, A ustralia, show 94% carious teeth before the
age of twelve. In the A ustralian aborigine, practically no caries was
found in children. T h e slight incidence of caries found among middle
aged skulls increased to 1% in skulls of aged aborigines.
C ooper’s rep o rt showed an appalling dental condition of the
children in the public schools of N o rth Carolina. H e says th at 80%
of all the school children enrolling in the public schools of N orth
C arolina— at that tim e m ore than th ree-fo u rth s of a million— were
in dire need of correction fo r dental defects. It was found th at not
over 5% of this g reat num ber had ever visited a dentist’s office for
any purpose w hatsoever.
A rep o rt by R ypins m ade on dental conditions in the pre-school
children of K ansas City. M issouri, is most enlightening if not start­
ling. Children in different districts all over the city were examined,
and m ore than 25% of the children from birth to six years of age
were found to have carious teeth. Between the ages of three to six,
44% w ere found carious. O f m ore than 8,000 children enrolled in
the first grade each year, 5,000 have dental defects. Tw enty-one

144

Journal o f the Tennessee A c a d e m y o f Science

th o u s a n d te e th w o u ld re q u ire su rg ic a l tre a tm e n t y e a rly to m ak e th e
pre-sch o o l c h ild re n o f K a n s a s C ity d e n ta lly p e rfe c t u p o n e n tra n c e to
school. T h is is a m ig h ty econom ic a n d h u m a n ita ria n pro b lem .
F rie l a n d S h aw re p o rte d on th e d e n ta l co n d itio n s a m o n g th e w h ite
ch ild re n in th e U n io n o f S o u th A fric a . S ix h u n d re d c h ild re n ra n g in g
fro m th e ag es o f six to six te e n show ed a n incidence of 9 3 .3 5 %
caries. O n ly 6 .5 5 % o f th e se c h ild re n h a d all so u n d te eth . T h e re
w as an av e ra g e o f 4 .8 2 % cario u s te e th p e r in d iv id u a l.
T H E O R I E S AS TO T H E

E T I O L O G Y O F D E N T A L C A R IE S

T h e etiology of d en tal c a rie s— “ th e m o st p re v a le n t of all h u m a n
d is e a s e s '’— has been th e s u b je c t o f d iscu ssio n by m a n y a u th o rs an d
m an y tre a tise s fro m th e e a rlie st o f tim es. V a rio u s h av e been th e
th e o rie s ad v an ced .
H ip p o c ra te s, 465 B. C., a ttrib u te d d e n ta l c aries to “ th e sta g n a tio n
o f d e p ra v e d ju ic e s ” in th e teeth . G alen, 131 A . D ., th o u g h t it a fo rm
of in flam m atio n , an d la te r J o h n H u n te r (1 7 7 8 ), Jo se p h F o x (1 8 0 6 ),
T h o m a s Bell (1 8 3 1 ), a n d B o e d e k e r (1 8 6 6 ) w e re s tro n g a d h e re n ts to
th e in flam m atio n th e o ry o f th e c au se o f d e n ta l caries.
In b o th E u ro p e an d A sia, it w as su p p o se d by m an y th a t w o rm s
g re w in to te e th a n d g n aw ed aw ay th e su b stan ce.
I n C h in a an d
Ja p a n , th e w o rd u sed to d e sig n a te c a rio u s to o th is “ w o rm to o th .”
In p a rts o f C hina, th e m o d e rn m e th o d f o r tre a tm e n t of to o th a ch e is
to b o re in to th e te e th “to let th e w o rm s o u t.”
SOME GENERALLY ACCEPTED FACTS

C O N C E R N I N G D E N T A L C A R IE S

B u n tin g defines d e n ta l caries as “ th e p ro c ess w h ich leads to a
d isin te g ra tio n o f th e te e th c h a ra c te riz e d by th e fo rm a tio n o f ’ open
lesions in th e enam el, d e n tin , a n d c e m e n tu m .”
H e says th a t th e g e n e ra lly accep ted fa c ts co n c e rn in g th e p ro cess
are :
1. D e n ta l caries is a d e stru c tio n o f th e h a rd su b sta n ce of th e
to o th by a p ro cess, th e in itial stag e o f w hich is decalcification by
acids.
2. T h e acid s activ e in c a rie s a re n o t g e n e ra lly d is trib u te d in th e
saliva, b u t a re localized a n d c o n c e n tra te d on c e rta in a re a s o f th e
to o th su rfa c e s.
3. C a rio u s lesions o ccu r m o st fre q u e n tly in th e p its a n d fissures
of th e occlusal s u rfa c e s an d o n c e rta in a re a s of th e a p p ro x im a l, buccal
a n d lin g u al s u rfa c e s o f th e te e th , a t w h ich lo catio n s th e re a re o p p o r­
tu n itie s fo r s ta g n a tio n a n d th e re te n tio n o f fo re ig n m a tte r. T h e y do
n o t occu r on sm o o th enam el s u rfa c e s th a t a re fre q u e n tly cleansed.
4. A ll in itia l lesions o f caries c o n ta in a c id -fo rm in g b a c te ria
cap ab le o f p ro d u c in g a n d liv in g in acid s o f sufficient p o te n tia l to
d ecalcify th e enam el.
5. T h e h a rd n e s s o r s o ftn e ss o f th e te e th m a y affe ct th e ra te o f
p ro g re s s an d e x te n t o f c aries b u t does n o t alo n e d e te rm in e its o c c u r­

Diet and Dental Caries in the Rat

145

rence. Caries, as a rule, runs a m ore rapid and extensive course in
hypoplastic teeth than in the hard and well form ed varieties, but in­
stances commonly occur in which the poorest-form ed teeth are wholly
free from the disease.
6. M alhygiene of the m outh frequently favors the inception of
dental caries and increases its activity, but alone does not determ ine
its occurrence. M ouths th at are habitually unclean are often wholly
free from caries and, conversely, m ouths th at are scrupulously clean
may be seriously affected by the disease.
7. T he process of dental caries is related to and often determ ined
by certain constitutional states and conditions of bodily health. T he
natu re of these general influences and the m anner in which th ey 1affect
the course of this dental disease are not clearly understood at this
time. T he following bodily conditions are perhaps best know n as
systemic factors which either favor or oppose dental caries :
H eredity. T here are strong evidences that the tendency tow ard
dental caries or tow ard im m unity to the disease m ay be transm itted
from p arent to child.
A g e. Susceptibility to dental caries is clearly influenced by age.
Incidence of the disease is know n to be highest during' the ages from
seven to tw enty years. A fte r tw enty years of age the tendency to
caries is m arkedly decreased.
H ealth. I t is frequently noted th at severe onsets of dental caries
follow attacks of general disease and disturbance of bodily health.
D u rin g pregnancy caries may be unusually active. C hildren who
are under-nourished or who are suffering from a general debility are
usually especially prone to dental caries.
Racial Influences. D ental caries is m ore prevalent in certain races
than in others. T he natives of A frica, South A m erica and the South
Sea Islands, the E squim aux and m any other prim itive peoples, are
notably free from the disease, while those who live in the m ore
civilized lands are extrem ely susceptible to it. T here are evidences
th a t the disease often increases in prevalence as people advance in
the scale of civilization. It is also observed that, when persons m i­
g rate from a caries-free nation to a country in which it is prevalent,
they and their progeny may later develop dental disease. T here is
no indication that dental caries is an endemic disorder or th at it is
induced by any climatic conditions. D iet is the only constant variable
betw een immune and susceptible races which thus fa r has been
recognized.
R

ecent

R

esearches

on

D

ental

C a r ie s

W hile dental caries is by no means a m odern disease, as shown
by previous references, there is no period in history when such an
interest in the problem has been shown as at present. W ith the
advances made in the science of nutrition and knowledge of the func­
tion of the vitam ins, and as the other elements of the diet become
better known, scientific research has now m ore than ever before been

146

Journal o f the Tennessee A c a d e m y o f Science

d ire c te d to w a rd th is p ro b lem . I n th e la st te n y e a rs re p o rts o f th e
in v e stig a tio n s o f th is s u b je c t by a w id e v a rie ty o f re se a rc h w o rk e rs
h av e occupied a p ro m in e n t place in th e m ed ical an d d e n ta l lite ra tu re .
T h e p o p u la r p re ss h as g iv en m u c h sp ace to th e d iscu ssio n o f th ese
re se a rc h re p o rts, in d ic a tin g th e ap p e a l th a t th e su b je c t m akes to th e
public. B ecau se th e a tta c k on th e p ro b lem is b e in g m ade fro m v ario u s
angles an d th e fin d in g s a re fra g m e n ta ry , d iffe re n t schools of th o u g h t
hav e a rise n g iv in g rise to m a n y co n flictin g sta te m e n ts as to th e cause
of th is disease. T h e p ro b le m is a co m p lex one, a n d it is inevitable
th a t th ese d ifferen ces m u st arise.
A t p re s e n t, becau se o f th ese
d iv e rg e n t o p in io n s a n d th e o rie s, th e p o p u la r m in d is c o n fu se d an d
ju stly so. T h e a u th o r aim s to re v ie w briefly th e w o rk o f th e m o re
im p o rta n t w o rk e rs in th is field.
(1)

v it a m in

d

and

d ental

c a r ie s

M rs. M e lla n b y w o rk e d w ith h e r h u s b a n d s tu d y in g th e effects of
rac h itic d iets on litte rs o f p u p p ies. S h e n o ticed a b n o rm a litie s in th e
te e th o f th ese p u p p ie s w h en fed on a d ie t c o n sistin g of se p a ra te d
m ilk, w h ite b read , o ra n g e ju ice, so d iu m ch lo rid e, y e a st a n d lean m eat.
W h e n th is d eficient d ie t w as su p p le m e n te d w ith cod liv e r oil, w hole
m ilk, b u tte r fa t, o r egg yolk, th e te e th a n d ja w s developed no rm ally .
T h e o b serv ed d e n ta l d e fe c ts w e re :
1. S o f t a n d p o o rly dev elo p ed ja w s a n d alv eo la r pro cesses in
w hich osteo id tissu e s o fte n to o k th e place o f bone.
2.

T e e th , chiefly lo w e r in ciso rs, c ro w d e d to g e th e r.

3.

A d elay in e ru p tio n .

4.

A d elay in calcification o f th e enam el.

5.

D eficient d en tin .

6. T h e g re a te r th e ra te of g ro w th , th e g re a te r th e d e fe c ts w hen
fa t soluble v ita m in D w as deficient.
T h e se a re clearly h y p o p la stic ch an g es in th e d e n ta l stru c tu re . In
a long series o f a rtic le s o v e r a p e rio d o f te n y e a rs, M rs. M ellan b y
trie s to show th e re la tio n sh ip b etw een h y p o p lasia o f th e te e th and
d e n ta l caries.
H isto lo g ic a l stu d ie s o f th e te e th o f do g s fe d on a d e q u a te a n d in ­
a d e q u a te d iets s h o w :
1.

T h a t g o o d d iets p ro d u c e d g o o d en am el a n d d e n tin .

2. T h a t a f te r th e ir fo rm a tio n te e th th a t a re fre e fro m d e n ta l
c aries h av e a good g ra d e o f se c o n d a ry d e n tin , a n d th a t te e th th a t
■are c a rio u s h av e a p o o r g ra d e o f d en tin .
M rs. M e lla n b y d u rin g re c e n t y e a rs re p o rts th e re su lts o f d ie ta ry
stu d ie s on ch ild re n . S h e re c o m m e n d s th a t c h ild re n be g iv e n d iets
w hich h av e b een show n to p ro d u c e p e rfe c tly fo rm e d te e th d u rin g
th e ca lc ify in g p ro c e ss, a n d also th e c o n tin u in g o f th e d ie t a lo n g
sim ila r lines a f te r th e te e th a re calcified. S h e believes th a t V ita m in

Diet and Dental Caries in the Rat

147

D is the all-im portant factor in the calcifying of the teeth. She is
opposed to and disagrees openly w ith those who at present place great
stress on V itam in C and its relation to caries.
She assum es th at hypoplasia and caries always correlate, but does
not explain why hypoplastic teeth o ften do not have caries. She
reports no studies on the bacteriological factor and rath er relegates
this to the background, refusing to consider it seriously at all. In
all her w ork she reports hypoplasia in puppies but no instances of
caries. T he author believes th at this is due to the conical shape
of the dog’s teeth which prevents food substances from adhering
to the teeth, and, although the causes of dental caries are present in
the dog's mouth, prevents the occurrence of the disease. M rs. M ellan­
by gives this no consideration whatever.
(2)

v it a m in

c and dpntad

c a rips

P ercy H ow e, D irector of the Forsythe D ental Infirm ary in Boston,
is representative of a class of investigators who feel th at V itam in C
is the all-im portant factor in the cause of dental caries. H is first
studies w ere on the m icro-flora of dental caries.
L ater, after the
dietary experim ents of Zilva and W ells who reported hypoplastic
changes in the teeth of guinea pigs fed on scorbutic diets, H ow e was
attracted to the dietary factors causing dental changes. It seems that
by m eans of a fat-free m ilk and oatmeal diet, H ow e produced the
first experim ental caries in teeth. W hen he adm inistered V itam in C
in the form of orange juice, the caries was arrested. T his opened up
an entirely new field of thought and study.
It is said th at H ow e produced in monkeys all of the dental diseases
w ith which the dentist ordinarily meets by feeding diets deficient in
the antiscorbutic factor. H e gives no room to the antirachitic factor,
V itam in D, neither does he lay any stress on the bacteriological factor
or to the shape of the teeth.
H e suggests the following as preventive dietary m easures for
dental caries :
1. Liberal am ounts of fresh natural foods which possess minerals
and vitam ins.
2. O ne pint of milk, which supplies the calcium needed for an
individual.
H e suggests the ingestion of a pint of orange juice daily.
M ilton Theo H anke of the U niversity of Chicago has corroborated
the findings of H ow e on pulp and dentin changes and has made many
beautiful histological specimens. H anke does not, however, believe
th at V itam in C is the all-im portant factor in dental caries but rather
thinks th at dentin and pulp changes, as well as those of the periodon­
tal tissues, are profoundly affected thereby. H e feels that V itam in

148

Journal o f the Tennessee A c a d e m y o f Science

C is ra th e r a specific fo r th e c u re o f g in g iv itis a n d p y o rrh e a ra th e r
th a n a specific fo r c aries p re v e n tio n .
(3 )

M IN E R A L

IM BA LA N C E

AND

DENTAL

C A R IE S

C. J . G riev es, u n d e r th e d ire c tio n o f E . V . M cC o llu m a t Jo h n s
H o p k in s U n iv e rs ity , b eg an a series o f stu d ie s o n calcium a n d p h o s­
p h o ru s im b alan ce an d d e n ta l d ev elo p m en t.
G riev es, b e fo re his
death , m en tio n ed th e p o ssib ility o f e n d o c rin e d istu rb a n c e as a fa c to r
in caries. H . K le in h as c o n tin u e d th e w o rk o f G riev es since his
death , c o n d u c tin g stu d ie s on sw in e as e x p e rim e n ta l an im als. D u rin g
th e last tw o o r th re e y e a rs he h as p u b lish e d sev e ra l a rtic le s w hich
seem to sh o w th a t m a n y d e n ta l ch an g es a re du e to p h o sp h o ru s an d
calcium im balance.
(4 )

h e a lth

an d

d e n ta l

c a rie s

H a ro ld F . H a w k in s o f th e U n iv e rs ity o f S o u th e rn C a lifo rn ia , h as
o b serv ed th e re la tio n sh ip b etw een d e n ta l caries, g e n e ra l h ea lth , a n d
m etabolic co n d itio n s. T h e e a tin g o f la rg e a m o u n ts o f cereals, p a stry ,
a n d o th e r a c id -fo rm in g foods, is said to be h ig h ly c o rre la te d w ith caries.
T h o se w ho h ab itu a lly a te a m o re alk alin e d iet w e re sa id to be fre e
fro m caries. H e em p h asized th e re la tio n b e tw ee n acidosis a n d caries
an d said th a t caries can be p re v e n te d only by b u ild in g u p a h ig h
alk alin e re se rv e . H e su g g e ste d a d iet to fu rn is h th is re serv e.
(5 )

b a c t e r ia

,

eood a n d

d en tal

c a r ie s

B u n tin g , P r o f e s s o r o f D e n ta l P a th o lo g y in th e D e n ta l College
o f th e U n iv e rs ity o f M ic h ig a n , is a tta c k in g th e p ro b le m of th e cause
o f d e n ta l caries in a m o st th o ro u g h -g o in g w ay. H is g ro u p includes
d e n tists, p a th o lo g ists, b a c te rio lo g ists, b io -ch em ists, a n d n u tritio n e x ­
p e rts. F o r m an y y e a rs B u n tin g h as h eld to th e acid th e o ry o f th e
cause o f d e n ta l caries. H e say s th a t th e o ne fa c to r w hich seem s to be
c o rre la te d w ith d en tal caries is th e p re se n c e o f B a cillu s a cid ophilus in
th e saliva, in d e n ta l lesions, o r in o th e r p a rts o f th e o ra l cavity. M a n y
th o u sa n d s o f p a tie n ts ’ m o u th s a t th e D e n ta l C linic in A n n A rb o r
have been c u ltu re d fo r B a c illu s a cid o p h ilus. W h e re th e o rg a n ism
w as p re se n t fo r an y le n g th o f tim e, ca rie s w as said to develop. T h is
bacillus m ay also be c u ltu re d fro m activ e ca rio u s lesions. B u n tin g
believes th a t a h ig h c a rb o h y d ra te d iet, esp ecially one ric h in su g a r,
len d s itse lf m o re re a d ily to fe rm e n ta tio n by acid o g en ic o rg an ism s,
th u s s ta rtin g th e cario u s lesions in th e teeth . H e believes th a t th is
is especially tr u e o f irre g u la rly fo rm e d te e th w h e re occlusion is
ab n o rm a l an d fo o d d eb ris re a d ily a d h e re s betw een th e te eth , being
w ed g ed in a n d n o t rem o v ed e x c e p t by m e c h an ic al o r b a c te ria l actio n .
S u c h to o th s u rfa c e s a d jo in in g su ch re te n tiv e spaces a re especially
p ro n e to caries.
F o r th e last tw o o r th re e y e a rs th is g ro u p o f w o rk e rs h a s been
c o n d u c tin g e x p e rim e n ts w ith se v e ra l g ro u p s o f c h ild re n u n d e r c o n ­
tro lle d d ie ta ry reg im es, as is o n ly p o ssib le in o rp h a n a g e s a n d o th e r
like in s titu tio n s. H is r e p o rt is th e m o st co m p re h en siv e y e t m ad e of

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experim ents along this line, w ith dental disease. T he diet in these
institutions was fortified w ith a quart of milk per day and large
quantities of fresh fru it and vegetables, with only a m inim um of
sweets. A fte r a period of m any m onths, very few if any new carious
lesions were observed. In a personal com m unication to the w riter,
he says, “ In one institution over a period of one year and nine m onths
am ong seventy-five children, we have found two pin-point cavities.”
T hese dietary studies have caused B unting and his group to believe
th at while Bacillus acidophilus may be very much dependent upon
constitutional factors, such as state of health and especially nutrition,
tooth stru ctu re and hardness (o r softness) , are not im portant factors in
dental caries because clinical findings show that m any hypoplastic
teeth are not carious. These w orkers stress the environm ental factors
which may lend them selves readily to impaction and subsequent
ferm entation of food debris, w ith bacterial action. These may be:
1.

A high carbohydrate diet.

2.

Irreg u larly arranged teeth.

3.

States of disturbed m etabolism and nutrition.
S U M M A R Y OB' H IS TO R IC A L WORK

1. D ental caries is not a m odern disease. This is indicated by
m any studies in paleopathology and paleodontology.
2. T his disease has been w ide-spread in prehistoric and historic
times. A t present it is the m ost prevalent of all hum an maladies.
3. P rim itive peoples seem to have the lowest incidence of caries.
W ith increasing civilization the disease increases.
4.

T h ere are
( a ) The
(b ) T he
(c ) T he
( d ) T he
(e ) The
(1 )
(2 )
(3 )
(4 )

several theories as to the cause of this disease.
inflam m ation theory.
w orm theory.
electrical theory.
acid theory.
theory of metabolic disturbance (N u tritio n al) :
V itam in C deficiency.
V itam in D deficiency.
Calcium phosphorus imbalance.
A com bination of metabolic disturbances.

5. P resen t day investigation is attacking the problem from a
variety of angles of approach. T he reports of these investigators
are still fragm entary, and various schools of thought have arisen.
6. Studies of this subject are still in their infancy. W hen all
factors have been considered by com petent investigators, our concept
of the disease, dental caries, bids fair to be more complete than at the
present time.

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_ 7. T h e r a t m ay be u sed to a d v a n ta g e as an e x p e rim e n ta l an im al
in th e s tu d y o f d e n ta l caries.
E

x pe r im e n t a l

V a rio u s in v e stig a to rs re p o rt th e o c c u rre n ce o f d e n ta l c aries in th e
m o n k ey , g u in e a pig, an d ra t. M a y M ellan b y sh ow ed th e effect o f
h ig h cereal d iets on th e te e th o f litte rs o f pu p p ies. S h e sta te s th a t
co m p arab le re s u lts h av e been fo u n d in th e ra t. T o o b se rv e th e
effect' o f c e rta in d iets on th e te e th o f th e ra t, p re su m a b ly w ith th e
o c c u rre n ce o f caries, an d to find a m e th o d fo r p ro d u c in g th is disease

Fig. 1. Mandibles from R ats Receiving Stock Ration. Nos. 1 and 7 are
n o rm al; all others show caries in different degrees of severity.

th a t it m ig h t be m o re th o ro u g h ly s tu d ie d w ith its v a rio u s c a u sa tiv e
fa c to rs , w as th e p u rp o se o f th is stu d y . T h e m e th o d of a tta c k w as
to fe e d h ig h cereal d iets c o m p a ra b le to th o se w h ich M ay M ellan b y
fo u n d to p ro d u c e h y p o p la sia in p u p p ies.
PROCEDURE

A n im a ls U sed. A n im a ls u sed w e re th e A lb in o a n d P ie b a ld s tra in s
o f r a ts o f k n o w n h e re d ity , w h o se p a re n ts w e re ra ise d a n d m a in ta in e d

Diet and Dental Caries in the Rat

151

on a stock ration consisting of, 60 per cent whole yellow corn meal, 30
per cent whole m ilk pow der, 6 per cent linseed oil meal, 3 per cent
a lfa lfa leaf meal, 1 per cent sodium chloride. A total of sixteen
series, w ith some 275 anim als, was used.
Care o f A nim als. T hese animals, w eighing from 40-60 gram s
each and averaging tw enty-eight days of age, w ere placed in circular
screen cages ten to twelve inches in diam eter and twelve inches
in height. T h e cages w ere of the raised-bottom type, thus keeping
the anim als from access to the feces. T hey were placed on granite
pans whose bottom s were covered w ith removable paper. T he cages
w ere cleaned twice per week. T he ration was placed in containers
so devised as to keep the rats from scratching out but a m inim um of
the ration. Distilled w ater in drinking tubes was given daily to

Fig. 2. Mandibles from Rats Receiving Corn Meal in Different Degrees of
Fineness. Nos. 1, coarse corn meal; 2, corn meal retained by a 20-mesh
sieve; 3, corn meal retained by a 40-mesh sieve; 4, corn meal retained by a
60-mesh sieve; 5, corn meal passing through a 60-mesh sieve; 6, ground oat­
meal.

th e anim als on the experim ental ration. T w o o r three rats of different
litters were placed in the sam e cage, and com pared with litter mates
on th e sam e diets o r variations of the diet. N egative and positive
controls w ere used w hen necessary and advantageous. T he rats were
w eighed weekly, and w eights recorded.
O bservations on A nim als. A nim als a fte r being on the ration for
from six to tw enty-tw o weeks w ere etherized, their mandibles and
skulls were rem oved and kept fo r fu rth e r observations. T he hum eri
and fem urs of m any of the anim als were rem oved and, afte r con­
tinuous extraction w ith hot alcohol fo r a seventy-two hour period,
w ere ashed and the percentage of ash determ ined. A technique for
the exam ination of the teeth of living rats was devised allow ing ob­

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Journal o f the Tennessee A c a d e m y o f Science

se rv a tio n s o f th e te e th to be ta k e n a t re g u la r in te rv a ls, sh o w in g
c le a rly th e tim e o f th e o c c u rre n ce o f th e d isease a n d th e ra te o f
th e p ro g re s s o f th e sam e. M a cro sco p ical a n d m icroscopical stu d ies
w e re m ad e o f th e teeth .

Fig'. 3. Comparison of Corn with Rice and H ard W h eat in the Production of
D ental Caries in Rats. Nos.. 1-7 are from rats w ith calcium carbonate in
the diet; Nos. la-7a from rats w ithout the calcium carbonate. Nos. 2-5 are
upper molars showing distinct cavities. Nos. 1 and la, oatm eal; 2-3 and
2a-3a, c o rn ; 4-5 and 4a-5a, ric e ; 6-7 and 6a-7a, wheat.

P re p a ra tio n o f D ie ts. T h e g ra in s , as th e y ellow c o rn a n d o ats,
w e re m ed iu m -fin ely g ro u n d in o u r o w n m ill. T h e veg etab les u sed
w e re b o u g h t fre s h a n d d rie d a t a te m p e ra tu re w h ich m a in ta in e d as

Diet and Dental Caries in the Rat

153

fa r as possible the vitam in content. A fte r drying they w ere finely
g ro u n d in a W iley mill.
T he various constituents of the diet were weighed and m ixed
thoroughly. T he rations were placed in the specially prepared cups
and kept constantly before the animals. Cod liver oil and orange
juice w ere pipetted and adm inistered directly to the individual
anim als. Some anim als were irradiated twice weekly under a m er­
cury vapor light at a distance of fifteen inches for tw o m inutes.
DESC RIPTION OF RESULTS

T he basal diet selected for the initial studies was characterized
by its high cereal (o atm eal), low calcium content, which certain in­
vestigators have found to produce poor skeletal as well as poor dental
developm ent. It was hoped th at a high incidence of dental caries
m ight accompany the condition of poor dental development. Anim als
on the basal diet showed decidedly subnorm al grow th and low ash

Fig. 4. Mandibles of Rats Receiving Stock Rations with Supplements of Vari­
ous Dietary Factors. Nos. 1, oatmeal; 2, coarse corn meal; 3, coarse corn
meal plus 1% cod liver oil; 4, coarse corn meal plus \% calcium carbonate;
5, coarse corn meal plus 1% tricalcium phosphate; 6, coarse corn meal plus
lcc. orange juice daily; 7, coarse corn meal plus 15-20 grams fresh cabbage
daily; 8, coarse corn meal plus 15-20 grams fresh carrots daily.

content of the bones. A sh determ inations on the hum eri and fem urs
gave the following results w ith the basal d ie t: hum eri, 38.6% ; femurs,
35.0% ; as com pared w ith hum eri, 50 .0 % ; fem urs, 50.0% , on normal
anim als fed the stock ration. T h a t the teeth of the anim als on the
basal ration were abnorm ally so ft was apparent by the excessive
w earing aw ay of both the lower and upper incisors, the latter showing
characteristic cupping. In no case was there the slightest indication
of dental caries.
T he inclusion of vegetables im proved som ewhat the grow th and
bone developm ent of the experim ental animal, although grow th was
still fa r below norm al. A gain no caries was observed. T he addition
of calcium carbonate, of cod liver oil, or the exposure of the animal

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to u ltra -v io le t irra d ia tio n re su lte d in p ra c tic a lly n o rm a l g ro w th a n d
bone d ev elo p m en t. C aries w as n o t o b se rv e d in th e se anim als.
W h e n th e b asal d iet w as su p p le m e n te d by. v a rio u s su g a rs, su ch as
su cro se, glucose, a n d lactose, in a m o u n ts up to 2 0 % o f th e ra tio n ,
th e re w as still no in d ic a tio n o f d e n ta l decay. D e n ta l caries, h o w ev er,
w as o b serv ed sim u lta n e o u sly in an im a ls in w h ich th e basal oatm eal
d ie t w as m odified by rep la c in g th e o atm eal w ith p o ta to e s (b o iled,
d rie d , a n d g ro u n d ) a n d in th e case o f th e a n im als on th e stock ra tio n .
In a s m u c h as th e o c c u rre n ce o f d e n ta l caries on th e sto ck ra tio n w as

Fig. 5. Photom icrograph of Longitudinal Section of Carious M andibular
M olars. One is impacted w ith food.

m o re su rp ris in g , it w as d ecided to s tu d y th e sto ck ra tio n th o ro u g h ly
to d e te rm in e th e cau se o f th e d e v e lo p m e n t o f d e n ta l c aries in th is
ra tio n .
I n view o f th e em p h asis p laced u p o n c e rta in d ie ta ry fa c to rs su ch
as V ita m in s A , C, a n d D , f o r p ro p e r d e n ta l d ev elo p m en t, th e stock
ra tio n w as su p p le m e n te d b y w h a t w as c o n sid e re d lib eral a m o u n ts o f
th ese fa c to rs , su p p lied as cod liv e r oil a n d o ra n g e juice. T h e se

Diet and Dental Caries in the Rat

155

factors, how ever, had no influence w hatsoever in preventing the ap ­
pearance of caries.
T h e addition of calcium carbonate or of tricalcium phosphate
failed also to have any effect in preventing dental decay. Glucose
and sucrose added to the extent of 20% to the diet did not seem to
increase the severity of the carious lesions. In order to make ob­
servations on as m any anim als as possible, use was made of a large
num ber of anim als belonging to the stock colony. O f 140 anim als
exam ined, 127 or approxim ately 90% had teeth in various stages of
decay.

Fig. 6. Photomicrograph from Ground Section of Teeth after Imbedding in
Georgia Rosin. Note that by this method enamel is preserved. The darkstained areas in the dentin show the softening effect of caries.

Since caries was observed w ith such regularity in anim als on the
stock ration, it was desirable to know how early dental decay
began. A ccordingly, two series of young anim als a fte r weaning were
placed on the stock ration, and anim als were selected from these and
killed at weekly intervals from six weeks and onward. Dental decay
was found as early as six weeks, although in some cases there was no
evidence of caries in anim als killed as late as ten or eleven weeks.
Inasm uch as this method did not perm it observations of the
progress of the caries to be m ade, it was felt im perative to devise

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Journal o f the Tennessee A ca d e m y o f Science

som e m eans o f exam ining' th e te e th in th e living' an im als.
ing ly an im als w ere a n e sth e tiz e d a n d stra p p e d on a rack.

A c c o rd ­

W ith th is im p ro v e d tech n iq u e, f u r th e r o b se rv a tio n s w ere m a d e as
to th e tim e o f th e first a p p e a ra n c e o f d e n ta l caries. A t this tim e it
w as o b serv ed th a t p a rtic le s o f fo o d w e re im p acted in th e in te rstic e s
of th e lo w er m o lars an d in th e cario u s lesions. O n clo ser o b se rv atio n
th ese p a rtic le s p ro v e d to be c o rn m eal. F ro m th is it a p p e a re d th a t
th e im p acted co rn m eal m ig h t be th e d e te rm in in g fa c to r in th e p ro ­
d u c tio n o f caries in th e ra ts.
F ro m o b se rv a tio n s p re v io u sly m ad e, in d ic atin g th a t in d iets co n ­
ta in in g oatm eal as th e sole cereal caries n e v e r developed, it seem ed
desirab le to rep lace th e c o rn m eal by o atm eal, as w ell as by fee d in g
definite m ix tu re s of th ese cereals. T h e re su lts o f th ese series in d icate
in a strik in g w ay th a t, as th e p e rc e n ta g e o f c o rn m eal is in creased , th e
incidence of caries follow ed in a lm o st m ath e m a tic a l e x ac tn e ss.
E q u a lly s trik in g w as th e to ta l ab sence o f caries w hen o atm ea l alone
w as u sed in th e diet.
C o rn m eal o f 40 m esh fineness a n d th a t p assin g th e 60 m esh w as
used. In th e ra tio n in w hich co rn m eal fin er th a n 60 m esh w as used,
no caries w as fo u n d . T h is w as also tru e of th e ra tio n in w hich o a t­
m eal w as su b s titu te d fo r th e c o rn m eal. C o rn m eal g ro u n d to 40
m esh p ro d u c e d caries b u t of less se v e rity th a n re g u la r stock ra tio n
co rn m eal.
D ISC U SSIO N

D istu rb e d n u tritio n a l balance, as lack o f m in e ra l o r v ita m in co n ­
te n t. h as been re p o rte d as a fa c to r in th e cause o f d e n ta l decay in
e x p e rim e n ta l anim als. I t has been a ssu m ed th a t p o o r sk e le tal a n d
d en tal d ev elo p m en t acco m p an y each o th e r. In v e stig a to rs do n o t ag ree
as to w h a t n u tritio n a l fa c to r is m o st im p o rta n t, som e h o ld in g th a t fa t
soluble V ita m in s A a n d D a re m o st im p o rta n t. S till a n o th e r g ro u p
is q u ite as c e rta in th a t V ita m in C is th e only d e te rm in in g fac to r.
Still o th e rs believe it to be a co m b in atio n o f se v eral n u tritio n a l fa c ­
to rs. In th is e x p e rim e n t, caries did n o t develop in d iets k n o w n to
be in a d e q u a te as ev idenced by v e ry p o o r g ro w th a n d s o f t te e th . In
strik in g c o n tra st, ta h ig h incid en ce o f c aries h as been p ro d u c e d in a
diet a d e q u a te in all th e n u tritio n a l fa c to rs k n ow n.
I n all th e n u tritio n a l stu d ie s th a t hav e been re p o rte d , th e physical
c h a ra c te ristic s o f th e d iet u sed seem to h av e been to ta lly d isre g a rd e d .
W h ile it is n o t th e p u rp o se o f th is d isc u ssio n in an y w a y to m inim ize
n u tritio n a l fa c to rs, a tte n tio n is called to a n o th e r fa c to r, n am ely : th e
m echanical o r physical n a tu re of th e d iet. T h is h as receiv ed little
o r no a tte n tio n .
T h a t p a rtic le s o f co rn m eal, a n d o th e r fo o d s o f a
an d size, im p act in th e te e th o f ra ts , h as been c learly
o b se rv a tio n s on dead an d liv in g an im als. In cases
p actio n s h av e been n o ted in living an im als, la te r

like co n sisten cy
p ro v e n by m an y
w h e re fo o d im ­
caries h a s been

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157

observed in the same spots. In the diets used in this experim ent, the
foods which w ere of the consistency to im pact most readily in the
teeth w ere m edium or finely ground corn meal, dried potatoes, and
medium-finelv ground wheat. These particles were also of such sh e
that they lent them selves readily to mechanical impaction in the in ter­
stices of the teeth, later to lead to ferm entation, acid production, de­
calcification of the enamel and open carious lesions of the enamel and
dentin. Bacteriological studies made on the m ouths of these rats
showed the presence of acidogenic m icro-organism s. T he histological
specimens show im pactions of vegetable tissue in the carious lesion.
It is believed th at no changes from w ithin the tooth, as of the tooth
pulp, odontoblastic layer of cells, change in dentin, etc., from those of
norm al teeth can be seen in the histological studies made.
O atm eal and finely ground corn, being of a softer and finer con­
sistency, do not have the physical characteristics which might lend
them selves to mechanical impaction, and therefore the absence of
dental caries in anim als on these diets.
T he contour of the m olars of the rat lends itself readily to
the im paction of food particles of the proper consistency and size.
W hen these particles are of a kind to be potential sources of ferm en­
tation, it is believed th at caries will be produced. B unting calls a t­
tention to the fact th at while dental hypoplasia has been repeatedly
reported in puppies by M ay Mellanby. yet no dental caries has been
observed. T his he believes to be due to the contour of the teeth, and
even suggests the im possibility of dental caries in the dog due to the
shape of the teeth. In clinical practice caries has been observed in
practically the same location on the same teeth in children of the same
fam ily who have inherited a sim ilar dentition.
It has been em phasized over and over again by dental clinicians
th at carious lesions occur m ost frequently in the pits and fissures of
the occlusal surfaces and on certain areas of the approxim al, buccal,
and lingual surfaces of the teeth, at which locations there are oppor­
tunities fo r stagnation and retention of foreign m atter. They do not
occur on smooth enamel surfaces that are frequently cleansed.
It is possible that the beneficial effects to the teeth reported by
w orkers in hum an nutrition, when large quantities of vegetables,
fru it and fru it juices are ingested, may be due to the cleansing effect
of those constituents of the diet as well as to the strictly chemical
or nutritional factors. Diets upon which dental im provem ent has
been observed, and those in which dental decay has been prevented,
are those in which the physical characteristics are such as to have
a cleansing effect on the teeth. W hen large quantities of fruits,
vegetables, and milk made up the bulk of the diet, the intake of car­
bohydrate is lowered, thus giving less opportunity for impaction of
potentially ferm entative food elements. T his seems to be a factor
overlooked by w orkers in this field of investigation.
D ental caries thus fa r observed and reported by McCollum (5 4 ),
Bracco (7 3 ), B unting (7 4 ), M arshall (7 5 ), and K now lton (76) have

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alw ay s been in th e m a tu re an im al. M a rs h a ll believes th e c arie s ob­
se rv e d in th e se a d u lt an im als to be co m p arab le to th e c arie s o f a d u lt
h u m a n s ; an d th a t activ e d e n ta l caries, w h ile p re s e n t in a d u lt h u m a n
beings, is reco g n ized as p re e m in e n tly a d isease o f ch ild h o o d . C arie s
in th is e x p e rim e n t h as been fo u n d re g u la rly in im m a tu re an im als,
ad v a n c e d caries b ein g o b serv ed in in d iv id u als b u t six w eeks on th e
diet.
I t is believed th a t a m e th o d o f e x p e rim e n ta lly p ro d u c in g c aries in
th e im m a tu re r a t h as been fo u n d . T h is m ak es po ssib le a stu d y o f th e
chem ical, h isto lo g ical, an d b acterio lo g ical ch an g es of th e te e th o f
such anim als. T h is sh o u ld be m o st w elcom e to in v e stig a to rs in te r ­
ested in th ese p h a se s o f th e p ro b lem .
B

1.
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8.
9.
10.
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Journal o f the Tennessee A ca d e m y o f Science

54. Grieves, C. J. and F . V. McCollum. A P relim inary Study of Gross
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Prevention of O ral Diseases by Correction of
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61. Boyd, J. D., and C. L. Drain. The A rrest of D ental Caries in Childhood.
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62. Boyd, J. D., C. L. Drain, and M. V. Nelson. D ietary Control of D ental
Caries. Amer. Jour, of Diseases of Children, 38 :721-725, 1929.
63. Drain, C. E-, and j. D. Boyd. D ietary Control of D ental Caries. Amer.
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69. Hanke, M ilton T. The Role of Diet in the Cause, Prevention, and Cure
of Dental Disease. Jour, of N utrition, 3:444, 1931.
70. Bunting, R. W ., and F aith Parm erlee. T he Role of Bacillus Acidophilus
in Dental Caries. Amer. Dent. A ss’n. Jour., 12:381, (A p ril), 1925;
Bunting, R. W., Gail Nickerson, and D orothy G. H ard. F u rth e r Studies
of the Relation of Bacillus Acidophilus to D ental Caries. D ental Cosmos,
68:931, (O c t.), 1926; Bunting, R. W ., Gail Nickerson, D orothy G. H ard,
and M ary Crowley. F u rth er Studies of the Relation of Bacillus A cid o ­
philus to D ental Caries, II. ibid., 70:1, (Ja n .), 1928; Bunting, R. W .,
M ary Crowley, D orothy G. H ard, and M argaret Keller. F u rth e r Studies
of the Relation of Bacillus Acidophilus to Dental Caries, I II , ibid.
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in Young Rats. Proceedings of Society for E xperim ental Biology and
Medicine, 27 :757.

161

Diet and Dental Caries in the Rat
A

ddendum

Since this paper was read before the Tennessee Academy of Science,
developm ents have come th at cause us to present the follow ing:
W a s the production o f caries in our rats due to a deficiency o f
phosphorus in the diet?
In recent com m ent by K lein and M cCollum,1 exception was taken
to the explanation th a t caries in our w ork2 was caused by the retention
of particles of corn meal by the teeth, w ith subsequent bacterial a c tio n ;
TABLE 1
The Lac\ of Relationship Between Phosphorus Content of Diet and Incidence of Caries
A verage
of

D iet

I.

C orn m e a l __________ __ _______
W h ea t g lu te n ___ ___ _______ __
W h o le-m ilk p o w d er......................
C risco...............
.
. . .
N a C l________ _______________

P arts

69
20
5
5
1
100

Ca

Gram

G am

C a / P Caries F e m u r s
and
R atio
H umeri

0 .2 00 1 0 . 0 0 9 6
0 .0400 0 .0 1 5 6 0 .263
0 . 0 4 2 0 0 .0 4 9 0

Per
Cent

Per
Cent

90-100

4 3.5

0 .2 82 1 0 .0 7 4 2
0 .2821 0 . 4 7 4 2

1 .68

90 -1 00

50.4

69
20
5
5
1

0 . 2 9 9 4 0 .0 7 6 2
0 . 0 4 0 0 0 .0156
0 .0420 0 . 0 4 9 0

0.41

0

45.5-

100

0 . 3 4 3 6 0 .1 4 0 8
0

51.9

S a m e d iet, w ith 1 per c e n t CaCOs..
II. O a tm ea l_______________________
W h e a t g lu te n ...................................
W h o le-m ilk p ow d er................. ....
C risco .
N a C l . . .....................................

P

S a m e d iet, w ith 1 per c e n t CaCOs..

0 . 3 4 3 6 0 .5408

1 .57

II I . S to c k ra tio n * ________ _______
(C oarse corn m eal)

0 .4 8 0 2 0 .3 4 2 4

0 .7

9 0-1 0 0

56 .2

*V alues g iv en b y K lein an d M cC ollu m .

and th at the fineness of the meal was an im portant factor in the pro­
duction of caries. K lein and M cCollum suggest that the caries in
o u r experim ents was due rath er to a deficiency of phosphorus in the
diet. W hile it is tru e th at the corn meal passing through a 60-mesh
screen was richer in phosphorus (ow ing to removal of some of the
1K lein and M cC ollum : Science, 7 4 : 6 6 2 ; December 25, 1931.
2H oppert, W ebber, and C a n n iff: Science, 7 4 : 77, July 17, 1931.

162

Journal o f the Tennessee A c a d e m y o f Science

b r a n ) , a n d th u s effected a slig h t in c re a se in th e p h o sp h o ru s c o n te n t of
th e ra tio n as in d ic a te d by th e a n a ly se s o f K le in a n d M cC o llu m , we
believe th a t th is d ifferen ce in th e in ta k e o f p h o sp h o ru s h a d n o th in g
w h a te v e r to do w ith th e d ev elo p m en t o f caries. F o r one th in g , it is
e x tre m e ly u n lik e ly th a t d iets su ch as o u rs, th a t h av e g iv en v e ry sa tis ­
fa c to ry re su lts fo r g ro w th , re p ro d u c tio n , a n d location, co u ld be
d eficient in so esse n tia l an elem en t as p h o sp h o ru s. M o reo v e r, d iets
c o n ta in in g o atm eal an d h a v in g a p p re c ia b ly less p h o sp h o ru s th a n th e
one co n sid ered by K le in a n d M cC o llu m to be deficient in th is elem ent,
h av e been fed w ith o u t p ro d u c in g caries a t all.
I t w o u ld a p p e a r
logical to conclude, th e re fo re , th a t th e d ev e lo p m en t o f c aries m ay,
w ith in c e rta in lim its a t least, be in d e p e n d e n t of th e p h o sp h o ru s c o n ­
te n t o f th e diet.
In tab le 1 a re re c o rd e d th e re su lts o b ta in e d w ith a n o th e r ty p e o f
d ie t th a t h as been u sed in o u r stu d ie s on d e n ta l caries. T h e p h o sp h o ru s
an d calcium v alu es h av e been calcu lated fro m th o se used by K le in a n d
M cC ollum . T h e d a ta fo r th e fe m u rs a n d h u m e ri h av e b een in clu d ed ,
because th ese v alu es e x p re ss a c c u ra tely th e ab ility o f th e d iets to su p ­
p o rt calcification o f th e bones a n d te e th . C o n c ern in g th e calcium p h o sp h o ru s ra tio s, it is obvious th a t th ese b e ar little re la tio n e ith e r to
th e incidence o f caries o b serv ed in th e ra ts, o r to th e ash c o n te n t of
th e bones. M o re o v e r, th e re is no c o rre la tio n w h a te v e r b e tw ee n th e
a sh c o n te n t o f th e bones an d th e in cid en ce o f caries. T h e d ev elo p m en t
o f caries in th e ra ts w as ju s t as f re q u e n t 011 th e c o rn m eal d ie t th a t
p ro d u c e d bones y ield in g 56.2 p e r cen t a sh as on th e co rn m ea l diet th a t
g av e b ones y ie ld in g only 43.5 p e r c e n t ash. I n c o n tra s t to th e se r e ­
su lts, caries w as n o t o b serv ed in a n y o f th e ra ts re ce iv in g th e o atm eal
diets, w h e th e r th e ash c o n te n t o f th e b o n es w as h ig h o r low .
T h e se re su lts p e rm it o f only one conclu sion, an d th a t is th a t v a r ia ­
tio n in th e p h o sp h o ru s c o n te n t o f th e d iets in o u r e x p e rim e n ts h a d no
co n n ectio n w ith th e outcom e. I t h a s alw ay s a p p e a re d r a th e r stra n g e
th a t w h e re a s a deficiency in th e d iet, be it an in o rg a n ic elem en t o r a
v itam in , cau sed g en era l m etab o lic d istu rb a n c e s, th e sam e deficiency
should, in th e case o f caries, affect one to o th an d leave th e a d ja c e n t one
u n to u c h e d . I t w o u ld be ju s t as re a so n a b le to e x p e ct one fe m u r of a
ra t, on a d eficient diet, to h av e a n a sh c o n te n t o f 40 p e r cent, a n d th e
o th e r fe m u r to h av e one o f 55 p e r cent. T h e lo calizatio n in th e decay
o f te e th is m o st re a so n a b ly e x p la in e d o n th e basis of a c tio n by c e rta in
fa c to rs e x te rio r to th e teeth . U n til a m o re p lau sib le e x p la n a tio n is
fo rth c o m in g , w e shall a d h e re to o u r o rig in a l co n clu sio n s co n c e rn in g th e
cau se o f th e c aries in o u r e x p e rim e n ts.