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The innervation of the teeth and periodontium of the rat

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The innervation of the teeth and periodontium of the rat

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Content THE INNERVATION O F THE TEETH A N D
PERIODONTIUM O F TH E RAT
by
S o l B ernick
A D is s e r ta tio n P resen ted t o th e
FACULTY O F TH E G R A D U A TE SCHO O L
UNIVERSITY O F SOUTHERN CALIFORNIA
In P a r t ia l F u lfillm e n t o f th e
R equirem ents fo r th e Degree
D O C T O R O F PHILOSOPHY
(Anatomy)
June 1955
This dissertation, written by
................... 8ol_BerrilGk................................
under the direction ofiX^JELGuidance Committee,
and approved by all its members, has been pre
sented to and accepted by the Faculty of the
Graduate School, in partial fulfillment of re
quirements for the degree of
D O C T O R OF P H I L O S O P H Y
Dean
Date..
nss-
Guidance Com m ittee
Chairman
1
TàELS OF GOroiOTS
CH A PTER PAG E
I* INTRGDHGTIOH ^ « 1
I I . HISTORICAL R EV IEW ............................................................. 3
I I I . MATERIALS ARD M ETH O D S ........................................ 26
IV . OBSERVATIONS...................................................................................29
C onneetive t i s s u e elem en ts . . . . . . . . . 29
I n c is o r s . . . . . . . . . . . . . . . . . . 31
M olars . . . . . . . . . . . . . . . . . 55
V. DISCUSSION............................................................................ . 41
VI. SUMMARY.................................................... 54
V II. LITERATURE CITED........................................... 58
V III. PLATES.................................................................................................69
CHAPTER I
INTRODUCTION
The d is t r ib u t io n o f n erres to th e t e e t h and t h e ir
periodontium has been w id ely stu d ie d as In d le a ted bjr th e
Innum erable r e p o r ts in th e l i t e r a t u r e . However, in s p it e
o f th e s e many in v e s t ig a t io n s , th e r e s u l t s have been lim ite d
in scope and are c o n tr o v e r s ia l in n a tu r e . They have been
m ainly d ir e c te d tow ards th e d eterm in a tio n o f th e manner
and typ e o f nerve endings th a t e x i s t in th e pulp or d e n tin
as w e ll a s in th e p e r io d o n ta l membrane and g in g iv a e . O n
th e o th er hand, r e fe r e n c e s con cern in g d e t a ile d sy stem a tic
s tu d ie s on th e b a sic p a tte r n s o f n erve d is t r ib u t io n t o th e
to o th and i t s fu n c t io n a lly r e la te d su p p o rtin g s tr u c tu r e s
are very sp a rse in number. T h erefo re, such a stu d y was
undertaken*
The r a t seemed to be th e anim al o f ch o ic e fo r t h i s
in v e s t ig a t io n as t h i s i s one o f th e most common e x p e r i
m ental a n im a ls. Yet l i t t l e in fo rm a tio n i s a v a ila b le con
cern in g th e t o t a l in n e r v a tio n o f i t s t e e t h . Furtherm ore,
th e r a t has a unique d e n tit io n in th a t i t has two func
t io n a l l y d if f e r e n t to o th ty p e s . The in c is o r , which con
tin u e s to d e v e lo p , m ature, and eru p t through th e l i f e o f
2
th e an im al, can be compared t o th e e a r lie r s ta g e s of
to o th developm ent o f humans and o th er mammals. On th e
o th er hand th e m olars are o f lim ite d growth and. a re simi*»
la r m o rp h o lo g ica lly to th o se o f th e h ig h e r form s. C©nse-
q u e n tly , one can stu d y sim u lta n eo u sly in t h i s anim al th e
n erve su p p ly to a d ev elo p in g to o th and t o a fu n c t io n a lly
mature to o th .
CHAPTER I I
HISTORICAL REVIEW
I.
The knowledge th a t t e e t h co n ta in n erv es goes fa r
hack in to a n tiq u ity . T aylor (1922) r e p o r ts th a t Galen in
h i s an atom ical s tu d ie s c l a s s i f i e d th e tr ig e m in a l nerve as
th e th ir d c r a n ia l n erv e. He fu r th e r reco rd s two s i t e s o f
p a in , one in th e to o th and th e oth er in th e surrounding
t i s s u e s . A etiu s (5 0 2 ) s ta te d th a t th e cause o f tooth ach e
was known o n ly t o God, and th a t th e mucous membrane o f th e
mouth i s in n erv a ted by branches o f th e th ir d c r a n ia l n erv e .
He a ls o observed sm a ll openings in th e to o th through which
tw ig s o f th e s e n erv es entered#
John Hunter (1778) w rote in h is "N atural H isto r y o f
th e T eeth" , th a t s e n s i b i l i t y e x i s t s in th e c a v ity o f th e
to o th and th a t t h i s is ,o w in g to th e n erve in th e c a v ity
(B rod ie 1 9 3 4 ). Duval (1835) showed th a t th e re i s s e n s a tio n
ju s t below th e enamel o f a to o th . Raschkow (1835) reco rd
ed , "Perhaps in no part o f th e body th e re e x i s t s th e extrem e
i t i e s o f n erv es p resen t so ev id e n t and b e a u tifu l in appear
ance as in th e d e n ta l pulp; th e n erv es a f t e r th e y have
s e v e r a lly or in bundles o f s e v e r a l branches e n ter th e pulp
4
o f th e to o th reced e more or l e s s from eaoh oth er and so in
sim p le fila m e n ts p a r tly sep arated and p a r tly combined pro
ceed to th e extrem e apex o f th e crown where th e y d iv id e by
d eg rees in to t h e ir sim p le st fila m e n ts w hich s w e llin g l i k e
rows o f beads c o n s t it u t e th e p r im itiv e s e r ie s o f v a r io u s ly
in te rr u p te d nervous a r t ic u le s b ein g accompanied in t h e ir
cou rse by a d e lic a t e c e llu la r t is s u e in order th a t th ey
might not d e v ia te from a s tr a ig h t l i n e . Under th e apex
th ey ag a in form a p lex u s from which fila m e n ts are g iv en o ff
term in a tin g lik e " p e n ie illi" at th e e x tr e m itie s o f th e apex.”
Owen (1848) concluded th a t th e n erv es p en etra te th e
o r i f i c e s o f th e fan gs and form a r ic h p lexu s w ith meshes
upon th e co ro n a l su r fa c e s o f the pulp. Furtherm ore, Owen
c i t in g P u r k in jie and Raschlow in regard to th e form ation of
th e d en tin sa id th a t th e se two ob serv ers noted th e embryonic
nervous t is s u e cannot be d is tin g u is h e d in th e pulp u n t il i t s
v a s c u la r it y had been e s ta b lis h e d . John Tomes (1848) found
f ib e r s in th e d en tin which he c a lle d n e r v e s. They were con
tin u o u s w ith th e pulp netw ork, and he co n sid ered th e s e f i b
r i l s to be th e cau se o f s e n s i t iv e d e n tin . L a ter, in 1865,
he changed h is o p in io n , as he was a b le to dem onstrate th a t
th e se f ib e r s were co lla g en o u s in n a tu re, th e s o - c a lle d
5
Tomes f ib e r s . B eale (I8 6 0 ) was the f i r s t t o b e lie v e th a t
th e n erv es ended in th e d e n tin . He though th a t th e re was
room in the d e n tin a l tu b u le s fo r whole p le x u ses of m inute
nerve f i b r i l s , and th a t th e n erves en te r th e d e n tin a l tu b
u le s in common w ith th e d e n tin a l f i b r i l s . F itch (1864)
h eld th e idea th a t th e d e n tin i s endowed w ith nerve f i b i l -
la e perhaps so m inute as to elu d e m icro sco p ic in v e s tig a tio n *
F ra n cis (1865) a year la t e r compared the s e n s a tio n in th e
to o th w ith g h o stly ten n a n ts in h a b itin g every c e l l o f th e
d e n tin and lik e tr u s ty s e n t in e ls g iv e warning o f approach
in g d anger. He fu r th er s ta te d th a t t h i s " d en tin a l l i f e
presence" was n ot e a s i l y photographed, and i t must emanate
from th e membrane sac which in v e s t s the p ulp , and t h i s l i f e
p resen ce was probably an e ffu s io n o f " liq u o r sa n g u in in is" .
M o Q u illen (1867) b e lie v e d th a t th e d e n tin owed i t s
s e n s i t i v i t y t o th e d e n tin a l tu b u le s . He sta te d th a t i f
n erve f ib e r s were d is tr ib u te d to a l l of th e d e n tin a l tu b
u le s every to o th under such circu m stan ces would be s e n s i
t i v e not on ly to th e m an ip u lation of th e d e n t is t , but ache
when exposed to th e therm al changes of everyday l i f e .
Burgh (1867) con sid ered s e n s it iv e d en tin as a p a th o lo g ic a l
phenomena but gave no rea so n . C u tler (1866) thought th a t
th e d e n tin a l tu b u le s con tain ed a nervous f lu id cap ab le of
6
being put in to rilJ ra tio n s which would tra n sm it im pulses to
th e p u lp .
B o ll in 1868, w h ile a m ed ical stu d e n t, was th e
f i r s t to attem pt h i s t o l o g i c a l l y t o dem onstrate th e term i
n a tio n s of nerve f ib e r s in th e p u lp . U sing a gold c h lo r id e
and chrom ic a cid method, he thought he was a b le to demon
s t r a t e nerve f ib e r s in the d e n tin . He s a id , "From th e
network beneath th e s u p e r f ic ia l c e l l la y e r some d e lic a t e
nerve f i b r i l s ascend v e r t i c a l l y to th e f r e e su rfa ce of th e
pulp and in s e r t in th e d e n tin a l tu b u le s . In s p it e of
d ecided proo'f, I am n e v e r th e le s s p e r f e c tly s a t i s f i e d th a t
th e nerve f i b r i l s p en etra te in to the d e n tin ."
W hite (1871) assumed th a t th e p r o c e sse s o f th e
o d o n to b la sts became con fused in th e ou ter coat o f th e
nerve w h ile Coleman (1871) was in c lin e d to regard th e
o d o n to b la st as comparable to th e t a c t i l e c o r p u sc le ,
P acin in an b o d ie s, rods and co n es, and o th er s p e c ia l recep
t o r s . He fu r th e r b e lie v e d th a t a co n n ectio n e x i s t s between
th e o d o n to b la st and th e nerve f ib e r . Harriman (1 8 7 1 ), in
B oston , claim ed to have dem onstrated by d ried ground
s e c t io n s a sm a ll nerve f i b r i l on s e v e r a l d e n tin a l f ib e r s
and a ls o to have d is s e c te d out one of th e s e nerve elem en ts
which were 1 /5 0 ,0 0 0 o f an in ch in d ia m eter. S a lte r (^1874)
7
s ta te d th a t th e n erves o f th e pulp formed lo o p s a t th e
p erip h ery , and i t was h ig h ly im probable th a t th ey p ierced
th e w a ll o f th e o d o n to b la sts . K o llio k e r (1867) s t a t e d ,
"As regard to t h e ir endings one s e e s here and th ere lo o p s
in th e p u lp , but i t i s beyond doubt th a t th ey are not l a s t
ff
W ell (1874) concluded in h is re p o r t th a t n oth in g
l i e s in th e way o f th e th eo ry th a t eaoh d e lic a t e f i b r i l o f
the b a sa l membrane i s a means of co n n ectio n between th e
nervous system and th e odontoblast^ and th a t th e s e odonto
b la s t s may be regarded as nerve e n d in g s.
M agitot and Le Gros (1879) examined th e pulps o f
t e e t h o f anim als w ith gold c h lo r id e and observed th e nerve
f ib e r s o f th e pulp to be d ir e c t ly con tin u ou s w ith th e
I
I c e n tr a l p r o c e sse s o f th e o d o n to b la sts . Boedecker (1882)
I s ta in e d th e pulps o f th e te e th from th e jaws o f a n in e
i
I month old f e t u s w ith gold c h lo r id e , and he tra ced m edul-
; la te d nerve f ib e r s to th e p eriph ery of th e pulp. Here th e
n erves l o s t t h e ir m yelin sh eath and s p l i t in to numerous
ex trem ely d e lic a t e beaded f i b r i l l a e . He found th a t th e
n erves are connected w ith the o d o n to b la sts by means of
c o n ic a l o f f- s h o o ts which end in k n o b -lik e e x t r e m itie s .
8 :
K lein (1893) found numerous m ed ullated f ib e r s form ing
p lex u ses w ith in th e pulp t i s s u e . At th e p erip h ery of th e j
pulp th ey lo s e t h e ir m edullary sh eath ,an d th e a x is c y lin -
I d ers probably ascend in th e d e n tin a l t u b u li. Sudduth ,
I i
! (1886) agreed w ith Boedeoker but fu r th e r s ta te d th a t th e ;
term in a l f ib e r s u n ite w ith the o d o n to b la sts .
R obertson (1890) sa id th a t th e o d o n to b la sts in th e
te e t h o f oxen were b ip o la r . L ater (1891) he a sse r te d th a t
th e o d o n to b la sts are neu rosensory c e l l s whose b a sa l p roc-
! e s s e s are d ir e c t ly con tinu ou s w ith th e nerve f ib e r s o f th e |
I d e n ta l p u lp . M orgenstern (1892) u sin g th e G olgi and m eth- j
I y le n e blue m ethods, concluded th a t th e nerve f ib e r s have \
i I
I fr e e term in a tio n s in th e pulp. He was a b le to tr a c e I
i ’
fib e r s e n te r in g th e d e n tin and ending in a k n o b -lik e
; enlargem ent from w hich a sh ort supplem entary f i b r i l e x -
Î :
' te n d s. W alkhoff (1892) regarded th e in te r g lo b u la r sp a c e s, ^
* th e gran u lar la y e r,a n d th e club -shap ed p r o c e s s e s , as
d escrib ed by M orgenstern, as m o rp h o lo g ica lly s im ila r .
Rose (1 8 9 3 ), who saw M orgenstern»s p r e p a r a tio n s, repeated
, h is work and reached th e co n lu sio n th a t M orgenstern*s
nerve endings were on ly area of u n e a lo ifie d ground sub
sta n c e s through w hich th e d e n tin a l f ib e r s p a ss. R etzu is
(1893) a p p lied th e G olgi method o f s ta in in g on t e e t h of
d if f e r e n t v e r te b r a te s . He came to th e co n c lu sio n th a t
9
I
n erv es end as fr e e beaded term in a tio n s among th e odonto
b la s t s and between th e o d o n to b la sts and the d e n tin . S tack !
(1896) t r ie d t o show th a t th e r e i s a s p e c ia l, developm ent
I o f nerve endings rea ch in g as fa r as th e in te r n a l su rfa c e
! ’
i o f th e enam el. He based h is o p in io n on th e very d e lic a t e i
sen se o f touch p o ssessed by th e to o th .
Huber (1898) sta in e d th e low er m olars o f r a b b its
' w ith th e in tr a -v ita m m ethylene b lu e . He found th a t th e
I n erv es o f th e pulp d iv id e in to numerous sm a ller bundles
i :
! and form a m ed u llated p le x u s. O n approaching th e p erip h - !
I *
I ery o f th e p ulp, th ey lo s e t h e ir m edullary sh eath and |
i I
1 form sm all p lex u ses deep w ith in th e o d o n to b la sts , and th ey I
1 I
j term in a te as beaded en d ings near th e f r e e end o f th e |
o d o n to b la sts . He found no nerve f ib e r s in th e d e n tin or
connected d ir e c t ly w ith th e o d o n to b la sts . Burchard (1898)
I t r ie d to confirm Huber’s work but doubted th e r e la t io n s h ip s *
th a t Huber d e sc r ib e d .
Romer (1 8 9 8 ), u sin g th e in tr a -v ita m m ethylene
b lu e , sta in e d th e t e e t h o f a th r e e week old k it t e n . He
thought he was a b le to tr a c e n erves in to th e d e n tin . He
fu r th e r s ta te d th a t th e g r e a te r part o f th e d e n tin a l
tu b u le s w iden out a t the enamel ju n c tio n In to cu rio u s
sp in d le -sh a p e d , p a r tly clubbed-shaped fo rm a tio n s. In
th e s e form ation s are found sm all rounded or o v a l
10
c o r p u sc le s which may he regarded as s im ila r to th e term in a l
c o r p u sc le s o f th e sen so ry n erv es o f th e s k in . Pont (1900)
b e lie v e d th a t th e o d o n to b la sts are somewhat li k e p er ip h e r a l
sen so ry n eu ron s, and are t r u ly n erve c e l l s o f w hich th e
d e n tin a l p r o c e sse s are th e c e n t r ip e t a l p o le s and th e b a sa l
p r o c e sse s th e c e n tr ifu g a l p o le s . Latham (1902) s a id , "In
th e pulp we fin d th e nerve, f ib e r s o r ig in a tin g from th e
m ed u llated n e r v e s. They be.oome non-m edulla ted and sm a lle r
u n t il th e neurilemma d isa p p e a r s, and th e bundles o f new
f i b r i l l a e break up in to t h e ir p r im itiv e shapes form ing
term in a l p lex u ses ju s t beneath th e o d o n to b la stic la y e r near
th e l i n e o f c e l l b o d ies or basement membrane which so fa r I
b e lie v e i s not d em onstrated , but i s b e st known and i s
d esc rib ed as th e b a sa i la y e r o f W eil. Nerve f i b r i l s run
beneath th e o d o n to b la sts; th e m a jo r ity so fa r b ein g l o s t
s ig h t o f but h ere and th e r e f i b r i l l a e may be seen p a ssin g
beyond th e p erip h ery o f th e c e l l in to th e form ing d en tin " .
Law (1 9 0 7 ), u sin g th e Boethe and G olgi m ethods,
came to the c o n c lu sio n th a t th e nerve f ib e r s are in th e
d e n tin , however he was n ot a b le to dem onstrate f ib e r s
e n te r in g th e o d o n to b la stic la y e r . He supposed th a t th e s o -
c a lle d p lex u s o f Raschkow did not e x i s t , but was m erely
made up o f bundles o f co n n e c tiv e t is s u e f i b e r s . He thought
he was a b le to dem onstrate nerve f ib e r s running in to th e
11
d e n tin in a hard ground to o th p rep a ra tio n .
Mummery (1 9 1 0 ), the le a d in g B r it is h d efen d er of
th e o p in io n th a t th e n erves en ter th e d e n tin , began h is :
I work a t th e b egin n in g o f th e cen tu ry , however i t was not i
I '
‘ u n t il 1910 th a t he was a b le to s a t i s f y h im s e lf th a t th e '
nerve f ib e r s e n te r th e d e n tin . In a s e r ie s o f s t u d ie s ,
s t a r t in g in 1910 and co n tin u in g to 1924, he s ta te d th a t a |
bundle o f nerve f ib e r s lo s e t h e ir mass o f n e u r o f ib r ils as
i
i t e n te r s th e d e n tin a l tu b u le s . B efore e n te r in g th e
I
d e n tin , th e f ib e r s form a m arginal p lex u s and en ter th e :
I i
! d e n tin in company w ith th e d e n tin a l f i b e r . He claim ed he ;
! I
! could tr a c e th e n erves as f in e , beaded f ib e r s term in a tin g \
; I
; in f in e r a m ific a tio n s o f th e d e n tin a l tu b u li beneath th e |
enamel and cementurn. In 1919 he found s tr u c tu r e s in t e r
posed in th e cou rse o f th e n erves which he con sid ered as
"nerve and c e lls " p laced im a row a t th e base o f th e |
' o d o n to b la s tic c e l l s . Mummery c a lle d th e d i s t a l p ro cess of '
, th e s e c e l l s e n te r in g th e d e n tin th e axon and th e p erip h era l
' p ro cess surrounding th e o d o n to b la st and h aving sy n a p tic
r e la t io n s w ith th e p lex u s o f Raschkow th e d e n d r ite s .
During t h i s p eriod Mummery began a correspondence
w ith H opew ell-Sm ith in England on th e co n tro v ersy regard in g
th e in n e r v a tio n o f th e t e e t h . H opew ell-Sm ith was th e c h ie f
advocate th a t th e n erv es end among th e o d o n to b la s ts . As
IE
e a r ly as 1903 he t r ie d to show th a t nerve f ib e r s end in a
basket-w ork o f v a r ic o s e f ib e r s em bracing and o fte n c l o s e ly
a tta ch ed to th e c e l l w a ll of th e in d iv id u a l o d o n to b la sts .
L ater in h is r e p o r ts he came to th e co n c lu sio n th a t th e
n erv es end s im ila r ly to th e te lo d e n d r ia o f th e o th er
ord in ary sen so ry n e r v e s. He fu r th e r contended th a t
Mummery’s f ib e r s in th e d e n tin were o n ly c o n n ectiv e t i s s u e
f ib e r s .
In th e d e fe n se o f h is work Mummery s a id , "I am
glad I have a t l a s t ob tain ed a d e f in i t e statem en t from th e
author (H opew ell-Sm ith) as to th e n atu re o f th e se f ib e r s
I have fig u r e d and d e sc r ib e d . He sa y s th a t th e y are
co n n ectiv e t is s u e f ib e r s " . The fo llo w in g l e t t e r s were
o ffe r e d by Mummery as ev id en ce th a t h is f ib e r s in th e den
t i n were o f nervous o r ig in , à l e t t e r from Sharpey-
S ch a fer to Mummery s t a te d , "I am q u ite convinced o f th e
nervous n atu re o f th e wavy f i b r i l s . D en tin seems to be
more r ic h ly su p p lie d w ith n erv es than any o th er t is s u e in
th e body". In a la t e r l e t t e r S h arp ey-S ch afer s a id , "I
have no doubt w hatever th e f i b r i l s you d e sc r ib e and fig u r e
are nervous - you are q u ite a t lib e r t y to say so " .
S ta r lin g w rote Mummery, " If th e f i b r i l s I saw in your
specim ens were not nerve f i b e r s , I have n ot seen nerve
f ib e r s " . C harles Tomes’ l e t t e r t o Mummery d is c lo s e d , "The
13
onus o f proof appears to me, th e r e fo r e , s h if te d to showing
th a t th ey are n ot nerve and t o d em onstratin g th a t th e y are
som ething e l s e , which seems to me very u n lik e ly ." From
Underwood, Mum#ery q u oted , "I have n ot seen o n ly one or
two but a g r e a t many o f your specim ens during th e l a s t few
y e a r s , and I have r e p e a te d ly fo llo w ed nerve fila m e n ts
r ig h t in to th e d e n tin ................... .1 have no lin g e r in g doubt
w hatever and th e e s ta b lis h e d f a c t th a t nerve fila m e n ts pass
in to th e su b stan ce o f th e d e n tin must now pass in to cu rren t
te a c h in g throughout th e s c i e n t i f i c w orld".
H opew ell-Sm ith (1924) co n tin u in g t h is co n tro v er sy
review ed e x te n s iv e ev id en ce to in d ic a te th e n o n -in n e r v â tio n
o f d e n tin and s t a t e s in c o n c lu sio n , "There are no n erv es in
th e d e n tin ; th e anim al economy does n ot re q u ir e them in
t h i s or any o th er c a l c i f i e d c o n n ectiv e t i s s u e . There i s ,
c o n se q u en tly , no s e n s a tio n in th e d e n tin . There i s no
h y p e r s e n s it iv it y o f d e n tin ”. On the o th er hand, Mummery
p e r s is te d th a t n erves e n ter th e d en tin and gave ev id en ce
based on h is work and work o f o th e rs and s a id , "I hope I
have proved to your s a t i s f a c t i o n th a t th e d e n tin i s sup
p lie d w ith n e r v e s. I f e e l th a t fu r th e r re sea rch i s n e c e s
sa r y w ith regard t o th e c e l l s (n erve end c e l l s ) , but th e
main f a c t o f th e in n e r v a tio n o f d e n tin i s , I h ope, f u l l y
14
e s t a b lis h e d ”.
Dependorf (1913-1915) was o f th e o p in ion th a t th e
n e u r o f ib r ils e n ter th e d e n tin where th e f ib e r s may pene
t r a t e th e Tomes f ib e r s in th e d e n tin or pass in th e ground
su b sta n ce o f th e d e n tin to th e den to-en am el ju n c tio n .
Here th e y end a s sim p le en d ings or s l i g h t l y bulbous t h ic k
e n in g s . B a r r it (1911) was an oth er ad vocate th a t th e n erv es
p ass in to th e d e n tin p a r a lle l to th e d e n tin a l f ib e r s and
f i n a l l y e n te r th e d e n tin a l tu b u le s . F r its c h (1914) u sin g
th e B ielsehow sk y and G ajal methods b e lie v e d th a t he g o t th e
same r e s u lt s as D ependorf, th a t i s , th a t th e f ib e r s pene
t r a t e th e d e n tin to e ith e r e n te r th e tu b u le s or end in th e
m a tr ix .
M on tfort, in a s e r ie s o f papers s t a r t in g in 1914
and ending in 1924, t r ie d t o dem onstrate th a t in th e
d e n tin a l pulp th e r e e x is te d two system s o f " tran sm issin g”
e le m en ts. One, a system o f s e n s i t iv e f ib e r s w hich end in
th e su b o d o n to b la stic la y e r s and d ir e c t s th e im p ressio n s
r e c e iv e d in the p u lp a l space to th e c e n te r o f p e r c e p tio n ,
and tw o, a system o f tr o p h ic f ib e r s which end among th e
o d o n to b la sts and tra n sm it th e s tim u li r e c e iv e d t o th e
in tim a cy o f th e elem en ts o f th e p u lp . In 1920 and 1923,
t h i s in v e s t ig a t o r added a th ir d elem en t, "the nerve end
c e l l s o f th e c e n tr a l p u lp ”, to th e a lr ea d y com plex p ic tu r e .
15
He a ls o s ta te d th a t he n o tic e d th e e x is te n c e o f n eu ro-
h la s t s and embryonic nervous c e l l s in d e n ta l f o l l i c l e s o f
new ly born c a t s .
S tew art (1 9 2 7 ), u sin g a gold c h lo r id e method,
undertook t o re p ea t Mummery’ s work. He was a b le to demon
s t r a t e f ib e r s d escrib ed by Mummery which resem bled n erv es
in c e r ta in of t h e ir c h a r a c t e r is t ic s . He fu r th e r showed
th a t s e c t io n o f th e in f e r io r a lv e o la r d e n ta l nerve d id not
cau se th e s e f ib e r s to d eg en er a te . He cou ld n ot dem onstrate
th e nerve end c e l l s o f Mummery and M on tfort. L a ter , in
1929, he found th a t th e f ib e r s in th e d e n tin were p resen t
a f t e r l ig a t io n o f th e tr ig e m in a l and sym path etic nerve
su p p ly . In c o lla b o r a tio n w ith Lewinsky in a s e r ie s o f
papers (1 9 3 5 -3 6 -3 8 ), t:he' showed th a t f ib e r s e n te r th e
od on togen ic zone (p r e d e n tin ) and p en etra te th e tu b u le s
d i r e c t ly , or can be tra ced to th e edge o f th e d e n tin where
th e y branch and ram ify in th e ground su b sta n ce th en appear
to e n te r th e d e n tin a l tu b u le s . They were th e f i r s t t o
tr a c e a nerve f ib e r back in to th e p u lp .
D ieck (1927) found n erve f ib e r s ex ten d in g in to th e
d e n tin a l tu b u le s where th e y accompanied or adhered to th e
d e n tin a l f i b e r s . These nerve f ib e r s were tra ced from one-
h a lf to tw o -th ir d s ways in to th e d e n tin . Tojada (1 9 2 7 ),
a p p ly in g e le c tr o -o s m o s is to specim ens t o remove e x c e ss
16 ,
a c id a f t e r d é c a l c if ic a t io n , found nerve f ib e r s en tered th e
d e n tin a l c a n a ls . He thought he was a b le to dem onstrate <
th a t th e n erv es le a v e th e p u lp , lo s e t h e ir m edullary sh eath
between th e o d o n to b la sts , and p a ssin g a c r o ss t h i s la y e r
en ter th e d e n tin a l ca n a l where th e y l i e upon th e d e n tin a l j
f ib e r . In th e tu b u le s th e s e f ib e r s branch and send sh o o ts :
!
Which end in o v a l th ic k e n in g s . During th e e a r l i e s t
developm ent of th e to o th , no nerve cou ld be shown to e x i s t j
in th e p a p illa im m ediately under th e enamel organ. T ojada,
how ever, f a i l s to connect h is f ib e r s w ith t h e ir g en era l
d is t r ib u t io n in th e pulp .
Down and Gross (1928) used th e t e e t h o f humans,
d o g s, c a t s , and rod en ts sta in e d by th e in tr a -v ita m m ethy- I
i
le n e b lu e and th e C ajal m ethods, and th e y claim ed t o show
im c o n tr o v e r tib le ev id en ce th a t nerve f ib e r s a rb o rize around;
th e o d o n to b la sts and then extend in to the d e n tin a l |
tu b u le s , as fa r as th e dento enamel ju n c tio n . Chase (1 9 2 9 )i
compared the r e s u lt s o f e le v e n d i f f e r e n t i a l s ta in in g or
im pregnation methods and showed th a t th e f ib e r s d escrib ed
by Mummery and o th e rs as nerve f ib e r s were id e n t ic a l w ith
von K o rf’s f i b e r s . He f a ile d to dem onstrate nerve f ib e r s
in th e d e n tin a l tu b u le s or m atrix ex cep t fo r a r g y r o p h illo
f ib e r s w hich he thought m ight p o s s ib ly be nerve f ib e r s
which e n te r th e tu b u le s , bend sh a rp ly and re tu rn back to th e
17
o d o n to b la s tic la y e r . Chase s t a t e s th a t th e nerve end c e l l s
d esc rib ed by Mummery, M ontfort and o th ers were n o t neuro
c y te s but f ib r o b la s t s concerned in th e form ation o f Von
K o rf’s f i b e r s . He adds th a t th e nerve f ib e r s in th e
o d o n to b la st la y e r were arranged as d escrib ed by R e tz iu s ,
Huber, and o th e r s . Cabarina (1929) in Germany tra ced
bundles of n erves running p a r a lle l w ith th e v e s s e l s . He
found th a t in th e c e n tr a l part o f th e pulp th e f ib e r s d i
v id e and form a f in e network a t th e edge o f th e p u lp .
S ev er a l f ib e r s p en e tr a te through the o d o n to b la stic la y e r
in to th e d e n tin . Whether th ey e n te r th e d e n tin a l tu b u le s
or n o t, he could not d i f f e r e n t i a t e . Papa (1929) d escrib ed
f r e e endings fo r th e n erv es among and between th e odonto
b la s t s and d e n tin .
Noyes (1921) and Orban (1928) have taken o p p o site
view s on th e q u e stio n . Noyes r e fe r r e d to Mummery’s work
and s a id , "Support fo r alm ost any id ea can be found in th e
lit e r a t u r e but many o f th e c o n d itio n s d esc rib ed have been
shown to be err o r s in m icro sco p ic in te r p r e ta tio n " .
R e fe r r in g to th e work o f Huber (1898) he s ta te d fu r th e r ,
"The n erve fib e r s have n ever been fo llo w ed in to th e
d e n tin a l tubes" and thus adapted th e th eory of c o n d u c tiv ity
o f s e n s a tio n by th e d e n tin a l f i b r i l and th e o d o n to b la st.
Orban (1928) on th e o th e r hand has s t a t e d , "The nerve
18
f ib e r s can be tra ced n ot o n ly t o th e d e n tin , bat in to th e
d e n tin I t s e l f , as has been shown by Mummery, M orgenstern,
and r e c e n t ly by Adrian (1926) and T ojada-D ieck (1927)" •
Calderon (1 9 5 1 ), a p p ly in g C a ja lfs tech n iq u e to th e
t e e t h o f r a t s , reached th e c o n c lu sio n th a t th e n erv es o f
th e pulp form bundles o f v a r io u s s i z e s which accompany th e
blood v e s s e l s . These bundles remain se p a r a te as fa r as th e
zone o f polym orphic c e l l s a t w hich p o in t c o l l a t e r a l s are
form ed. At th e l e v e l o f th e c e l l s , th e bundles d iv id e , and
th e f ib e r s in te r m in g le among th e o d o n to b la sts . They end
in exp an sion s w hich are c lo s e to th e n u c le i o f th e s e c e l l s .
C alderon could tr a c e f ib e r s th a t c r o s s th e o d o n to b la stic
la y e r to approach to th e edge o f th e d en tin where th e f ib e r s
t r a v e l between th e l a t t e r and th e o d o n to b la s ts . He found
no n erv es in th e d e n tin or nerve c e l l s in th e p u lp .
S e e ly (1932) stu d ie d te e th fix e d in fo rm o l,
d e c a lc if ie d in HCl and HNOg, and sta in e d by th e
B ielsehow sk y p eth od . He thought he was a b le to tr a c e
n erve f ib e r s p a ssin g through th e o d o n to b la sts to e n ter th e
d e n tin where th e n erv es p en etra te th e tu b u le s .
T ieg s (1932) came to th e c o n clu sio n th a t n erv es can
be fo llo w ed through th e zone o f o d o n to b la sts in to th e sub-
)
d e n tin a l zone (p r e d e n tin ). Here th e y can be fo llo w ed as
e x c e e d in g ly f in e v a r ic o s e branching fila m e n ts w hich end ip
19
d e f i n i t e end o rg a n s. Some very d e lic a t e nerve f ib e r s
appear to term in a te in m inute s w e llin g on th e b o d ies o f
th e o d o n to b la sts . No nerve f ib e r s were observed to e n te r
th e d en tin , and no nerve c e l l s w ere seen in th e p a lp . In
h is second paper (1938) he b e lie v e d th a t n erve f ib e r s ran
in to the p red en tin term in a tin g in Tomes f ib e r s by means o f
d e f in i t e en d -o rg a n s, or th a t n erv es may end on th e b o d ies
o f th e o d o n to b la sts . Gordon and Jorg (1933) d escrib ed th e
nerve f ib e r s as term in a tin g in s p e c ia l beads in th e pre
d e n tin la y e r and s ta te d t h a t , as fa r as th e y are concerned,
th e f ib e r s do n o t have any co n ta ct w ith th e p r o c e sse s o f
th e o d o n to b la sts .
R ie g e le (1933) d escrib ed an in n e r v a tio n o f d en tin
by means o f f ib e r s w hich, a f t e r a sh o rt or lo n g coarse in
th e d e n tin , a l t e r t h e ir d ir e c t io n and appear to form a
term in a l nerve n e t . The n e o r o f ib r ils w hich he observed
w ith in th e d e n tin are sa id to be surrounded by n u clea ted
neuroplasm a s h e a th s .
Munich (1934) showed by th e m od ified osmium ta n n ic
method th a t nerve f ib e r s come from th e pulp and run between
th e o d o n to b la sts , and pass in to th e d e n tin . The f ib e r s
d id not fo llo w th e d e n tin a l tu b u le s , but proceeded in to
th e m atrix to end in a k n o b -lik e body w hich he thought
were s im ila r to g a n g lia n c e l l s .
20 I
Von der S pren kel (1 9 3 4 ), a p p ly in g B ielsehow sk y and
Be C astro te o h n iq u e s, in human and mammalian t e e t h , demon- :
s tr a te d th a t p u lp a l n erves form a network between th e
o d o n to b la sts and th en e n te r th e d e n tin . In th e d e n tin
th e y tak e an in te r tu b u la r co u rse on or are embedded in th e
f ib e r s o f Tomes and end in d e lic a t e r in g s or s p i r a l s . The !
o d o n to b la sts were not in n erv a ted and are n ot t o be regarded-
' as sen so ry c e l l s .
Hammer (1937) found th a t in a 3 1 .7 mm. f e t u s th e I
i I
j n erv es pass in to th e r e g io n o f th e p a p illa e s in c e th ey I
I I
j proceed w ith th e blood v e s s e l s . T his occurs b efo re th e |
j p resen ce o f th e o d o n to b la sts . |
I Hr ad Tow (1 9 3 6 ), in England, u sin g th e s t a in s of |
I B ielseh o w sk y , G ras, W iegert, and C ajal in fr o ze n and
s e r i a l p a r a ffin and c e llo id a n s e c t io n s has in v e s tig a te d
th e d e n ta l in n e r v a tio n o f man, monkey, dog, c a t , e t c . He
; d esc r ib ed th e in n e r v a tio n o f th e to o th germ and th e n atu re
I
o f th e growing f i b r i l s . He c a lle d s p e c ia l a t te n t io n t o th e
in n e r v a tio n of th e p e r id o n ta l membrane. He was unable t o
fin d d eg en era tio n o f n erv es o f d eciduous t e e t h p rio r to
c a s tin g . In 1939 he found th a t th e f ib e r s d escrib ed by
Mummery were u n a ffected a f t e r s e c tio n in g o f th e in f e r io r
d e n ta l n erv e. He tra c e d nerve f ib e r s form ing sim p le or
complex lo o p s in th e p red en tin and o th ers which rum
21
t a n g e n t ia lly between th e o d o n to b la stic la y e r and th e d e n tin
t o form d e f in i t e nerve p le x u se s . A ttached t o th e s e
I
f ib e r s are numerous rounded, pear-shaped b o d ies w hich may
be nerve c e l l s or end organ s. He a ls o thought he was a b le
i 1
, to dem onstrate nerve f ib e r s p e n e tr a tin g th e d e n tin .
Wasserman (1939) stu d ie d th e in n e r v a tio n o f th e
d e n tin in r a t s . He came to th e co n c lu sio n th a t th e re were i
two ty p es o f n erv es in th e p u lp . One typ e p a sses in to th e ;
; d e n tin whereas th e second ends in th e p u lp , h avin g fr e e i
and in t e r c e llu la r ending w ith in W e il’s la y e r and among th e 1
! '
i o d o n to b la sts . !
i 1
j W eathford (1 9 3 9 ), w orking on th e r a t ’s t e e t h usingj
I d if f e r e n t te c h n iq u e s , d escrib ed fin e m ed u llated nerve fib e r j
i I
■ e n te r in g th e in c is o r t e e t h and en d ing in th e o d o n to b la stic
! la y e r . The nerve f ib e r s appear in th e in c is o r s about th e
tim e o f th e eru p tio n o f th e t e e t h . In th e f i r s t m olar :
I th e y appear about th e te n th day a f t e r b ir t h . Complex su b -
i
■ o d o n to b la stic p le x u se s are not seen u n t il l a t e r . At th e
I
, 30th day p le x u se s are seen im crowns o f th e th ir d m olars
and are e x t e n s iv e ly d is tr ib u te d in a l l th r e e m olars a t 45
d a y s. In th e in c is o r s and m o la rs, p r io r to s e n i l i t y , most '
o f th e f ib e r s are not found beyond th e en tra n ce t o th e
d e n tin . They e it h e r term in a te as f in e beaded endings or
fa d e out to a p o in t.
BE
W ellin g (1940) in In glan d b e lie v e d th a t he oonld
d e f i n i t e l y se e f i b r i l s in s id e th e d e n tin . He s a id , **If
th e r e i s any lik e lih o o d o f th e f i b r i l s b ein g Von K o r f's
f i b e r s , t h i s p o in t would s e t t l e th e q.nestion fo r th e
l a t t e r are not connected w ith and are n ot a part o f th e
m a trix ”. He a ls o concluded th a t i t i s o n ly tow ards t h e ir
te r m in a tio n s th a t th e f ib e r s tak e on th e lo o p s and s p ir a ls
th a t have been d e sc r ib e d , and i t i s here th a t th e d i f f i
c u lty o f d is t in g u is h in g them from th e Von K orf*s f ib e r s
l i e s .
I I . FERI0D0ÎÎT4L
The s t u d ie s o f th e in n e r v a tio n o f th e p e rio d o n ta l
membrane o f man and o th er mammals are v ery sc a n ty and
lim ite d to th e in n e r v a tio n o f th e p e r io d o n ta l membranes o f
th e permanent t e e t h . Dependo rf (1913) s ta te d th a t th e
nerve bundles found in th e p e r io d o n ta l membrane form both
co a rse and fin e netw orks w hich term in a te as f in e p oin ted
p r o c e sse s in th e ce m en to b la stio la y e r . Kadnoff (1929)
a p p lie d th e B ielsoh ow sk y tech n iq u e on t e e t h o f two human
in d iv id u a ls and found th a t th e nerve f ib e r s w hich a r is e a t
th e a p ic a l area o f th e to o th pass v e r t i c a l l y towards th e
g in g iv a l m argin b ein g r e in fo r c e d a t in t e r v a ls by nerve
bundles e n te r in g th e p e r io d o h ta l membrane through th e
23
foram ina in th e a lv e o la r bone. The term in a l nerve f ib e r s
a r is in g from th e se main bundles appear to form a f in e
network in th e membrane proper w ith ou t e n te r in g th e
oementum,and no en ca p su la ted nerve en d in gs w ere demon
s t r a t e d .
Von der S p ren k el (1936) d escrib ed th r e e ty p e s o f
en d in gs fo r th e n erv es in th e membrane(1) r in g s s itu a te d
v ery near th e a lv e o la r bone on th e c o lla g e n o u s f ib e r s
ex ten d in g from i t t o th e cementum; (2 ) term in a l r e t ic u la r
en d in g s in a s s o c ia t io n w ith c o n n e c tiv e t is s u e c e l l s ; and
(3 ) r e t ic u la w ith r a d ia l f ib e r s t h a t p en etra te in to th e
cementum and in some c a s e s in to th e d e n tin a l tu b u le s .
Bradlaw (1936) n o tic e d th a t nerve tw ig s were g iv e n o f f a s
th e main bundles accompanied th e blood v e s s e l s , and th e y
term in a ted as lo o p s and c o i l s su p p ly in g th e a lv e o la r bone
and cementum.
Stew art and Lewinsky (1 9 3 6 , 1937) stu d ie d th e
in n e r v a tio n in man and c a t and showed th a t th e term in a tio n
o f th e nerve f ib e r s are of two ty p e s: (1 ) th o se th a t are
co n fin ed to th e p e r ip h e r a l part of th e membrane w hich
have s p e c ia liz e d end organs: (2 ) f in e r nerve f ib e r s w hich
p ass to th e deeper part o f th e membrane and break up in t o
f in e a r b o r iz a tio n s w ith o u t term in a l o rgan s.
24
I I I . GINGIVAL INNERVATION
Jurjewa (1913) d esc r ib ed two ty p e s o f nerve end
in g s in th e g in g iv a e o f v a r io u s a n im a ls| (1 ) en ca p su la ted
en d in gs s itu a te d in th e s u b e p it h e lia l c o n n ectiv e t i s s u e s
and s im ila r in m orphology to th e t a c t i l e c o r p u sc le found
\
in o th er mucous membranes; and (2 ) n o n -en ca p su la ted end
in g s w hich c o n s is te d o f a network o f In te rm in g lin g th ic k
and t h in n erve f ib e r s lo c a liz e d in th e c o n n ec tiv e t i s s u e
p a p illa e between th e r e t e pegs o f th e e p ith e liu m .
Kadnoff (1928) found both n o n -en ca p su la ted and
en ca p su la ted nerve en d in gs in th e g in g iv a e . He d iv id e d
th e n on -en ca p su la ted ty p e s in to c lo s e and lo o s e c o i l s .
The c lo s e c o i l en d ings c o n s is te d o f both th ic k and th in
nerve f ib e r s arranged in t ig h t b a lls s itu a te d in th e
c o n n e c tiv e t i s s u e p a p illa e . Term inal nerve f ib e r s emerged
from th e se b a lls and en tered th e e p ith e liu m . The lo o s e
c o i l s , on th e o th er hand, a ro se from th e su b p a p illa r y
la y e r and passed in to th e p a p illa e as lo o p s f i l l i n g th e
domes. Two ty p e s o f en ca p su la ted en d in gs were d escrib ed
found deep in th e s u b e p it h e lia l t is s u e : (1 ) end bulbs o f
Krause and (2 ) th e touch c o r p u s c le s .
Kokubun (1929) gave an account o f th e in n e r v a tio n
o f th e human g in g iv a w hich d iff e r e d l i t t l e fr o # th a t o f
25
Kadnoff.
Stew art and Lewinsky (1 9 3 8 , 1939) made a compara
t i v e stu d y of th e in n e r v a tio n o f th e g in g iv a and came to
th e c o n clu sio n th a t th e c lo s e and lo o s e c o i l s th e y found
were not d if f e r e n t from th o se d esc rib ed by th e above
w ork ers.
Bradlaw (1939) found p lex ifo rm n erve f ib e r s
resem b lin g s u b e p it h e lia l lo o s e c o i l s in e a ts and v a r ic o s e
i n t r a e p it h é lia l f ib e r s in sh eep . In man he saw en d ings
s im ila r to th o s e found by Kadnoff and Stew art and
L ew insky.
CHAPTER I I I
MATERIALS A N D M ETH O D S
The t e e t h and th e jaws used in t h i s stu d y were
from w h ite r a t s o f th e U n iv e r s ity o f Southern C a lifo r n ia
s t r a in v a ry in g in age from th r ee t o f i f t e e n w eek s. A
t o t a l o f t h i r t y r a t s was u sed . Im m ediately a f t e r s a c r i
f i c e , th e an im als were d e c a p ita te d ; some o f th e heads
were s p l i t in h a lf by a m id s a g itta l c u t between th e r ig h t
and l e f t in c is o r s w h ile o th e rs were cu t in such a manner
th a t a b lo ck o f t i s s u e which co n ta in ed a s in g le m olar,
cou ld be s e c tio n e d in a b u ccal lin g u a l d ir e c t io n . The
b lo ck s o f t is s u e were fix e d in a m ixture o f form ol a c e t ic
a c id , 80^ a lc o h o l and sa tu ra ted p ic r ic a c id fo r a t le a s t
fo u r d a y s. The f ix a t i v e form ula i s as fo llo w s :
Form alin 5 c c .
A c e tic A cid 5 c c .
80^ e th y l a lc o h o l.................. . 90 c c .
S atu rated p ic r ic a c i d . . . . . 100 c c .
Ten p ercen t n i t r i c a cid in fo rm a lin was used f o r
d é c a l c i f i c a t i o n . S in c e i t s p e n e tr a tio n i s r a p id , e x c e s s iv e
a c tio n o f th e a c id on th e s o f t t i s s u e was a v o id ed . The
b lo ck s were prepared fo r s e c tio n in g by th e n i t r o - c e l l u l o s e
embedding m ethod. They were dehydrated in 7 0 $ , 95 $ , and
a b so lu te a lc o h o l; i n f i l t r a t e d in 10 $ , 25$, 50$ n it r o
c e llu lo s e ; and f i n a l l y embedded in 50$ n i t r o - c e l l u l o s e .
27
The n lt r o - o e llu lo s e h lo ek s were ea t in t o s e c t io n s 25-100
m iera t h ic k . Such t h ic k s e c t io n s a ffo r d a b e tte r means
o f o b ta in in g th e d e s ir e d c o n t in a ity of nerve f ib e r s than
do t h in s e c t io n s .
In ord er t o d if f e r e n t i a t e between th e co lla g en o u s
elem en ts and n erv es a d ig e s t io n method was undertaken.
Some o f th e b lo ck s were d ig e s te d b efo re d eh yd ration in 1$
p ep sin fo r a t l e a s t two d a y s, and th en w ith a 1$ tr y p s in
d ig e s t io n fo r one d ay. Other b lo ck s were s e c tio n e d , and
a lte r n a te cut s e c t io n s were exposed to th e a c tio n o f each
o f th e above enzymes fo r 12 hours or m ore. F ollow in g a
t r i a l o f a number o f s i l v e r im pregnation m ethods, i t was
found th a t P earson*s s i l v e r g e la t in im pregnation tech n iq u e
had a g r e a te r s e l e c t i v i t y fo r th e p e r ip h e r a l n erves when
th ic k s e c t io n s were im pregnated. B r ie f ly th e procedure
i s o u tlin e d below :
1 . P la ce s e c t io n s in 2$ AgNOg o v e r n ig h t.
2. Wash in a d ju sted w ater (15 drops o f 1$ c i t r i c
a c id in 1 l i t e r o f w a te r ).
3 . Reduce in a s o lu t io n o f hydroquinone, 4 c c ;
2$ AgNO^, 10 c c; 3$ g e l a t in , 40 c c .
4 . Wash in a d ju sted w a te r.
5 . Tone in 1$ gold c h lo r id e .
6 . Wash in d i s t i l l e d w a ter.
28
7 . P la ce in 1$ o x a lic a c id u n t il s e c t io n s have
a f a in t purple c o lo r .
8 . Wash in d i s t i l l e d w a te r.
9 . P la c e in 5$ h y p o s u lf it e .
D ehydrate and c le a r .
1 1 . Mount.
CHAPTER IV
OBSERVATIONS
I . CONNECTIVE TISSUE ELEM ENTS
The s i l v e r im pregnation method n ot on ly c o lo r s
th e p erip h e r a l n e r v e s, but b lack en s th e co n n ectiv e t i s s u e
elem en ts o f th e p u lp , p e r io d o n ta l membrane, and g in g iv a e .
Not o n ly may th e se s i l v e r im pregnated f ib e r s be m istaken
fo r n e r v e s, but th e y may a ls o mask th e n erv es in th e
r e g io n s s tu d ie d . In th e p ro cess o f im p regn ation , th e s e
d e n se ly arranged f ib e r s may become co lo red b efo re th e
n e r v e s , and as a r e s u lt hamper t h e ir i d e n t i f ic a t i o n . I t
was a ls o observed th a t th e ground su b sta n ce of th e con
n e c t iv e t i s s u e may in h ib it th e im pregnation o f n erve
f ib e r . T h is occurred p a r t ic u la r ly in th e lo o s e c o n n e c tiv e
t i s s u e o f th e pulp o f th e m o la rs. To e lim in a te both th e
non-nervous a r g y r o p h ilic f ib e r s and ground su b sta n ce an
enzym atic d ig e s t io n method was undertaken. With t h i s
ch em ical procedure th e in t e r f e r in g elem en ts were removed,
and th e t o t a l d is t r ib u t io n o f n erv es to an area was un-
I masked. T h is i s i ll u s t r a t e d in fig u r e s 3 and 4 . The
form er i s a s e c t io n o f th e lin g u a l p er io d o n ta l membrane
, o f an upper in c is o r w hich was n ot d ig e s te d w ith p ep sin and
I
i _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
3 0
t r y p s in . A la r g e nerve i s observed e n te r in g th e p e r io
d o n ta l membrane, but th e c o n n e etiv e t is s u e elem en ts have
masked i t s f in e b ran ch es. The s e c t io n o f fig u r e 4 , on
th e o th er hand, was d ig e s te d w ith th e enzym es. Hot o n ly
are th e la r g e n erv es o b serv ed , but th e f in e branches are
now v i s i b l e . The e f f e c t o f th e enzymes on th e ground
su b stan ce i s seen in f ig u r e s 8 and 9 . In fig u r e 8 , th e
s e c t io n o f th e pulp o f an upper f i r s t m olar was im preg-
’ nated w ith o u t d ig e s t io n , and th e ground su b sta n ce and
I c o lla g e n o u s elem en ts o f th e pulp have masked th e t o t a l
I
I nerve su pp ly t o t h i s s tr u c tu r e . The s e c t io n o f fig u r e 9 ,
I in c o n tr a s t, was exposed t o th e a c tio n o f th e enzymes
1
w hich d estro y ed th e co lla g e n o u s elem en ts and depolym erized
i
I th e ground su b sta n ce . C on seq u en tly, th e p ro cess p erm itted
i
th e im pregnation o f th e n erve f ib e r s and r e s u lte d in a
c le a r e r v is u a liz a t io n o f th e nerve su pp ly t o th e pulp o f a
The d egree o f d ig e s t io n was not uniform through
out th e same s e c t io n . T h is v a r ia tio n depended upon th e
amount o f co lla g en o u s elem en ts p r esen t in th e d if f e r e n t
s tr u c tu r e s of th e d e n t it io n . The pulp o f th e m o la rs,
fo r exam ple, w hich c o n s is t s o f lo o s e c o n n e ctiv e t i s s u e i s
e a s i l y d ig e s te d a s il l u s t r a t e d in fig u r e 9 . However, th e
I co n n e c tiv e t is s u e components o f th e p e r io d o n ta l membrane
31
and g in g iv a e are o n ly p a r t ia lly d ig e s te d due to th e heavy
c o n c e n tr a tio n of c o lla g e n o u s f ib e r s (fig # 10, 12)# T h is
p a r t ia l lo s s o f f ib e r s i s s u f f i c i e n t to perm it an a ccu ra te
i d e n t i f i c a t i o n o f nerves#
I I . INCISORS
S in ce th e upper and low er in c is o r s are so s im ila r
in m orphology, i t would be redundant t o d e sc r ib e each
se p a r a te ly # H ence, th e in n e r v a tio n o f th e upper in c is o r
i s d e sc r ib e d . The in c is o r , w hich i s a c o n tin u o u sly grow
in g to o th , c o n s is t s o f a crown, and la c k s th e t y p ic a l
to o th r o o t found in th e m o la rs. The m ajor p o rtio n o f th e
crown i s embedded between two p la te s o f a lv e o la r bone, a
I su p e r io r n a sa l p la t e , c a lle d th e la b ia l a lv e o la r bone,
! (L a. A .B. ) , ( f i g . 1 ) , and an in f e r io r o r a l p la te c a lle d
j th e lin g u a l a lv e o la r bone, (L i. A .B .) , ( f i g . 1 ) . The
I crown may be d iv id ed lo n g it u d in a lly in to a l a b i a l p o r tio n
I covered by enamel and i t s o u ter form ative la y e r , th e
I enam el organ, and th e lin g u a l and l a t e r a l p o r tio n s w hich
I are covered o n ly by cementum. The l a b i a l enamel organ i s
{ sep a ra ted from th e o v e r ly in g bone by a h ig h ly v a sc u la r iz e d
j c o n n e c tiv e t i s s u e la y e r c a lle d th e l a b ia l a lv e o la r
p eriosteu m ( f i g . 2 ) . The co lla g en o u s f ib e r s o f t h i s
la y e r run in a d ir e c t io n p a r a lle l t o th e lo n g a x is o f th e
32
bone as do th e v a sc u la r str u c tu r e s* The lin g u a l p e r io
d o n ta l membrane a tta c h e s th e cementum t o th e a d ja cen t
bone, and i t s attachm ent f ib e r s are u s u a lly arranged in a
r a d ia l d ir e c t io n ( f i g . 3 ) .
L in gu al P e r io d o n ta l Membrane
The lin g u a l p e r io d o n ta l membrane r e c e iv e s i t s
nerve supply from th e a n te r io r su p e r io r a lv e o la r n er v e .
T his n erve a r is e s from th e m a x illa r y nerve in th e r e g io n
o f th e upper f i r s t m olar and d escends in f e r i o r l y and
a n te r io r ly to th e H arderian gland d iv id in g in to two
b ran ch es. One branch, th e lin g u a l p e r io d o n ta l n e r v e , w ith
th e accompanying blood v e s s e ls e n te r s th e lin g u a l a lv e o la r
bone and em erges from th e bone a t th e m id -re g io n . The
n erve im m ediately d iv id e s in to fo u r f a s c i c u l i as i t e n te r s
th e p e r io d o n ta l membrane. Each f a s c ic u lu s p a sses in a
d if f e r e n t r e la t io n s h ip t o th e in c is o r ; th a t i s , one
co u rses a n t e r io r ly , one p o s t e r io r ly , one m e d ia lly , and
one l a t e r a l l y ( f i g . 3 ) . In i t s cou rse through th e p e r io
d o n ta l membrane each f a s c ic u lu s g iv e s o f f branches alm ost
a t r ig h t a n g le s . These branches con tin u e to d iv id e and
form many f in e netw orks which e v e n tu a lly term in a te as
f r e e nerve en d ings among th e strom al c e l l s o f th e
c o n n ectiv e t i s s u e a d ja cen t to th e a lv e o la r bone. B esid es
33
th e s e f a s c ic u la r tw ig s in th e p e r io d o n ta l membrane, r e
cu rren t p e r fo r a tin g branches may be seen p e n e tr a tin g th e
a lv e o la r bone ( f i g . 4 ) .
Pulp
The p u lp a l n erv es o f th e in c is o r are c o n tin u a tio n s
o f th e p o s te r io r trunk o f th e lin g u a l p e r io d o n ta l n erv e.
The p o s te r io r trunk becomes p r o g r e s s iv e ly sm a lle r as i t
approaches th e b a sa l p o rtio n of th e i n c i s o r . Here i t
c o n s is t s o f a few nonm edullated nerve f i b e r s . In th e
od ontogen ic zo n e, w hich i s th e fo rm a tiv e area o f th e
p u lp , th e sm a ll nerve bundles are in c lo s e cen tactw w ith
th e blood v e s s e ls ( f i g . 5 ) . In t h is fig u r e a c r o ss s e c t io n
o f a nerve may be observed b ord erin g a blood v e s s e l. Two
tw ig s are o r ig in a tin g from t h i s main n e r v e . One p a sse s
towards th e a d v e n titia o f an ad ja cen t v a sc u la r s tr u c tu r e ;
th e o th er e n te r s th e pulp accompanying a blood v e s s e l .
These sm a ll n erv es co n tin u e w ith th e blood v e s s e ls deep
in to th e p u lp . In a d d itio n to th e se n erv es o th er th in
wavy a r g y r o p h ilic f ib e r s (P c) stream in g in to th e pulp are
n oted in fig u r e 5 . These f ib e r s are n ot n erv es s in c e
th e y are a b sen t in t i s s u e s d ig e s te d by p ep sin and t r y p s in .
C on seq u en tly, th e y must be p reco lla g en o u s and co lla g e n o u s
34
I
in n a tu r e . Such f ib e r s could be e a s i l y m istaken fo r
n erv es when th in s e c t io n s are used and c o n tin u ity i s l o s t .
L ab ial A lv eo la r P eriosteu m
The blood v e s s e l s and accompanying sm a ll n erv es
from th e od on togen ic zone proceed in to th e l a b ia l a lv e o la r
p erio steu m . These sm all nonm edullated n erv es co n tin u e
t o be in tim a te ly a s s o c ia te d w ith th e blood v e s s e ls as
th ey tr a v e r s e th e w hole le n g th o f th e p eriosteu m . No
la r g e nerve f ib e r bundle could be found in t h i s a r e a .
e
I The lin g u a l and l a b ia l g in g iv a e o f th e upper
j in c is o r co n ta in a r ic h p lex u s o f n e r v e s. These n erv es
I are d eriv ed from th e n a sa l branches o f th e a n te r io r
su p e r io r a lv e o la r nerve as w e ll a s from th e a n te r io r
I trunk of th e lin g u a l p e r io d o n ta l n erv e . As th e y e n te r
I
I th e co n n e ctiv e t is s u e o f th e g in g iv a e , th ey u n ite w ith
I th e n erv es a r is in g from th e a d ja cen t labium and co n tin u e
; deep in to th e tu n ic a propria o f th e g in g iv a e . As t h i s
common trunk proceeds deep tow ards th e m arginal b ord er,
term in a l branches a r is e and pass towards th e s u b e p it h e lia l
r e g io n ending e t th e base of th e e p ith e liu m ( f i g . 6 ) . A
i few n erve f ib e r s can be tra ced in to th e e p ith e liu m .
35
I I I . M O L A R S
P a lp a l In n e rv a tio n
p a tte r n s o f th e in n e r v a tio n o f th e upper and
low er m olars are s im ila r . In g en er a l both m edulla ted and
I
I nonm edullated n erve f ib e r s le a v e th e m iddle su p e rio r
: a lv e o la r nerve a s th e d e n ta l nerve which d iv id e s in to two
I
! or th r e e f a s c i c u l i as i t tr a v e r s e s th e bone. These
i
I branches f i n a l l y e n te r th e a p ic a l area o f th e to o th .
I F igu re 7 i s a s e c t io n from th e a p ic a l area o f th e d i s t a l
I
I r o o t o f an upper f i r s t m olar and i s a t y p ic a l example o f
j th e oth er r o o ts o f th e m o la rs. In t h i s s e c t io n two sm a ll
f
jnerve f ib e r s may be seen em erging from th e u n d erly in g bone
to r e u n ite in to a la r g e nerve bundle in th e opening o f th e
a p ic a l foram en. B efore th e s e combined n erv es e n te r th e
foram en, branches are g iv e n o f f th a t su p p ly th e v a r io u s
s u r fa c e s o f th e p e r io d o n ta l membrane. As th e p u lp a l nerve '
p roceed s c o r o n a lly , no branches or term in a l tw ig s are
1
observed su p p ly in g th e pulp p o rtio n o f th e r o o t proper.
O n reach in g th e co ro n a l p o rtio n o f th e t o o th , th e p u lp a l
I
nerve breaks up in to an e x te n s iv e p lex u s as i l l u s t r a t e d in j
fig u r e 9 . T h is s e c t io n in c lu d e s th e d i s t a l cusp and part !
o f th e m iddle cusp o f an upper f i r s t m olar. From t h i s
36
p lex u s m ed u llated and nonm edullated n erve f ib e r s a r is e
th a t pass in a l l d ir e c t io n s t o su p p ly th e p u lp a l t i s s u e of
a l l th e su r fa c e s o f th e cu sp . These f ib e r s co n tin u e t o
d iv id e u n t il th e y reach th e o d o n to b la stic la y e r . Here
th e y term in a te as naked f ib e r s among th e o d o n to b la s ts . Ho
: term in a l f ib e r s were observed e n te r in g th e p red en tin or
I
I d e n tin . A la r g e n erve bundle le a v e s t h i s cu sp a l network
I
to pass tow ards th e m iddle cusp where i t forms an a n a sto -
i m osls w ith th e n erve bundle o r ig in a tin g from th e m e sia l
cusp ( f i g . 9 ) . The nerve p a tte r n s fo r th e m iddle and
m e sia l cu sp s are s im ila r t o th a t o f th e d i s t a l cusp ju s t
; d e s c r ib e d .
i
! P e r io d o n ta l Membrane In n erv a tio n
I
I
The pathway th a t th e n erv es fo llo w in t h e ir
cou rse through th e p e r io d o n ta l membrane o f th e m olars
depends upon th e su r fa c e in n e r v a te d . The nerve su p p ly to
th e in terp ro x im o 1 a r e a , th e r e g io n between two a d ja cen t
t e e t h , i s d if f e r e n t from th a t t o th e o th e r su r fa c e s
su rroun ding th e t o o th . The nerve to t h i s area may o r i g i
n a te d ir e c t ly from th e a lv e o la r nerve or as a branch o f
th e d e n ta l n erve as se en in fig u r e 7 . A nerve bundle
p a sse s th e le n g th o f th e membrane w ith o u t r e c e iv in g r e
in fo rcem en ts from p e r fo r a tin g n erv es a r is in g from th e
!
in t e r s 8p ta l bone. As t h i s main in terp ro x im o 1 nerve p a sses
g in g iv a lly , tw ig s are g iv e n o f f which d iv id e and f i n a l l y
term in a te among th e c e l l s and f ib e r s o f th e membrane ( f i g .
1 0 ) . Above th e a lv e o la r c r e s t th e main bundle breaks up
in to f i n e r a m ific a tio n s w hich become embedded in th e
tr a n s e p ts 1 f ib e r s . A p lex u s i s formed in th e tr a n s e p ta l
f ib e r s o r ig in a tin g w ith th e f ib e r s from a com parable
nerve o f th e ad ja cen t to o th . T h is nerve p lexu s c o n tin u es
in to th e fr e e g in g iv a l area to su p p ly th e in terp ro x im a l
g in g iv a e .
The in n e r v a tio n o f th e rem aining s u r fa c e s , o th er
than th e in terp ro x im a 1 , i s uniform in p a tte r n . These
in c lu d e th e m e sia l su r fa c e o f t h e upper f i r s t m olar, th e
d i s t a l su r fa c e o f th e upper th ir d m o la rs, and b u ccal and
lin g u a l su r fa c e s o f a l l th e m o la rs. The n erv es w hich
su p p ly th e s e s u r fa c e s are from two so u r c e s. One s e t o f
f ib e r s a r is e s from th e d e n ta l nerve b efo re i t s en tra n ce
in to th e a p ic a l foramen ( f i g . 7 ) . T his group o f f ib e r s
c o n tin u e s to p ass g in g iv a lly w ith i t s branches su p p ly in g
th e stroma o f th e membrane. The second group, th e in t e r -
a lv e o la r or p e r fo r a tin g b ran ch es, ascen d s through th e
in t e r a lv e o la r bone and p e r fo r a te s through th e bone a t
v a r io u s l e v e l s to e n te r th e p e r io d o n ta l membrane. F igu re
11 shows two p e r fo r a tin g a lv e o la r n erv es e n te r in g the" ^
38
p e r io d o n ta l membrane and u n itin g w ith th e d e n ta l branch to
form a s in g le b un dle. As t h i s nerve p roceed s tow ards th e
g in g iv a , o ffs h o o ts a r is e and term in a te among th e c o n n e c tiv e
t i s s u e o f th e membrane. In a d d itio n th e n erve f ib e r s
p a ss in c lo s e p roxim ity to th e a lv e o la r bone and cement um.
For exam ple, in fig u r e 12 a term in a l f ib e r i s seen d escen d
in g from th e main nerve trunk and p a ssin g to th e cem ento-
b la s t ie la y e r where i t breaks up in to f in e a r b o r iz a tio n
a d ja cen t t o th e cementum# From t h i s network f in e f i l a
m ents e n te r th e cementum. In a d d itio n k n o b -lik e nerve
en d in gs are observed in th e stroma o f th e p e r io d o n ta l
membrane.
G in g iv a l In n erv a tio n
The g in g iv a l r e g io n o f th e in terp ro x im a l area r e
c e iv e s i t s nerve su p p ly from e x te n s io n s o f th e n erve
p lex u s lo c a te d in th e f r e e g in g iv a l area o f th e p e r io
d o n ta l membrane. These n erv es co n tin u e in to th e tu n ica
p rop ria where fu r th e r branchings occur ( f i g . 1 3 ) . These
n erv es appear to term in a te a t th e s u b e p it h e lia l b ord er.
A few te r m in a tio n s can be se en p e n e tr a tin g th e e p ith e liu m
and p a ssin g a sh o rt d is ta n c e in t h i s la y e r . No s p e c ia liz e d
end organs were o b serv ed .
The g in g iv a e o f th e s u r fa c e s o th er than in t e r -
proxim al r e c e iv e t h e ir nerve su p p ly from two so u r c e s . The
39
f i r s t group o f nerve f ib e r s i s a c o n tin u a tio n from th e
p e r io d o n ta l membrane n erv es w hich send f ib e r s beyond th e
a lv e o la r c r e s t tow ards th e cement©enamel ju n c tio n t o t e r
m inate in r e la t io n to th e e p i t h e l i a l attachm ent and
c r e v ic u la r e p ith e liu m . The second group i s from th e
!
I l a b i a l or p a la ta l n erv es w hich cou rse tow ards th e m argin al
jg in g iv a and ram ify in to a r ic h network ( f i g . 14)# A ll o f
th e s e branches from both groups p ro g ress to th e su b -
- e p i t h e l i a l area where a few term in a te a t th e base o f th e
I ep ith eliu m # A few nerve f ib e r s p ass in to th e co n n e c tiv e
I t i s s u e p a p illa e , and some a c t u a lly p e n etra te th e e p it h e -
Ilium fo r a sh o rt d is t a n c e . The n erves th a t are seen in th e
* tu n ic a propria and p a p illa e may form lo o p s , b ru sh es, or
!
■ s k e in s b efo re th e y f i n a l l y end. These en d in gs appear as
inaked f i b e r s , and a t no tim e was a s p e c ia liz e d n erve ending
such as M eissu er^8 noted ( f i g . 1 5 ).
! P a la t a l In n erv a tio n
The mucous membrane o f th e p a la te a d ja cen t t o th e
: t e e t h i s r ic h ly in n e r v a te d . Branches from th e main
I p a la tin e nerve tr a v e r s e th e p a la te in a d ir e c t io n p a r a l-
' l e l i n g th e lo n g a x is o f th e bone. When th e main nerve
itru n k rea ch es a ruga a la r g e branch o r ig in a te s ( f i g . 1 6 ) .
I T h is la r g e branch p a sses d i r e c t l y towards th e apex o f th e
40
ruga sen d in g branches p e r ip h e r a lly in e it h e r a s t r a ig h t
or wavy c o u r s e . Some o f th e s e f ib e r s r e v e r s e t h e ir cou rse
to become recu rren t tw ig s in th e tu n ic a p r o p ria . O thers
term in a te in th e c o n n e c tiv e t is s u e b ord erin g th e e p i t h e l i a l
la y e r w h ile th e a p ic a l branches ram ify in to a network w hich
sen d s te r m in a l fila m e n ts in to th e e p ith e liu m . The r e g io n s
betw een th e ruga© co n ta in r ic h s u b e p it h e lia l r a m if ic a t io n s .
CH APTER V
DISCUSSION
r a t le a d s i t s e l f r e a d ily to a stu d y o f t o t a l
n erve d is t r ib u t io n t o th e d e n tit io n and periodontium
s in o e i t s s iz e i s such th a t one can s e c t io n th e in t a c t
head and tr a c e f a i r l y co m p letely th e nervous pathways
from th e main tru nk s in th e a lv e o la r bone to t h e ir term i
n a tio n s in th e t e e t h and su p p o rtin g s t r u c t u r e s .
D em onstrable c o n tin u ity o f f in e n erve f ib e r s in
th e p u lp , p e r io d o n ta l membrane, and g in g iv a e w ith th a t of
th e a lv e o la r n erv es or t h e ir main branches i s e s s e n t i a l
b efo re th e t o t a l n erve d is t r ib u t io n t o th e a re a s in ques^
t io n can be d eterm in ed . Nerve fragm ents and even s e r i a l
s e c t io n r e c o n s tr u c tio n by th e use o f th in s e c t io n s are
open to m is in te r p r e ta tio n . T h is fa c to r was d is c u s s e d by
th e author in a p rev io u s p u b lic a tio n (1 9 4 8 ). However,
when one u ses th e t h ic k s e c t io n , th a t i s , 25-100 micra
t h ic k , th e b a sic nerve p a tte r n s can be o b ta in e d . For
exam ple, in one th ic k s e c t io n o f 100 m icra th e o v e r a ll
n erve d is t r ib u t io n t o th e pulp o f an upper m olar can be
v is u a liz e d a s i l l u s t r a t e d in fig u r e 9 . To r e i t e r a t e , i t
i s ob viou s th a t by th e use o f th ic k s e c t io n s o f an in t a c t
r a t ' s head, th e upper and low er th r e e m olars as w e ll as
42
th e in c is o r s can he cut in one s e c t io n , and co n seq u en tly
th e nerve d is t r ib u t io n may be dem onstrated in I t s
e n t ir e t y . I t seem s c le a r th a t o b se r v a tio n s made by t h i s
method are more v a lid and l e s s s u b je c t t o m is in te r p r e ta
t io n than th o se made by r e c o n s tr u c tio n from th in s e r i a l
The in v e s t ig a t o r s who r o u t in e ly use th e v a rio u s
s i l v e r im pregn ation methods r e a liz e th a t th e s e tech n iq u es
are c a p r ic io u s . Not o n ly do nerve f ib e r s become im
p regn ated , but c o n n e c tiv e t is s u e elem en ts are a ls o
b lack en ed . I t i s w e ll known th a t th e p e r io d o n ta l membrane
and th e g in g iv a e are r ic h in th e s e c o lla g e n o u s elem en ts
which pass from th e cementum o f th e to o th t o th e surround
in g bone and c o n n ectiv e t i s s u e p a p illa e o f th e g in g iv a e .
These co lla g e n o u s and p r ec o lla g e n o u s f ib e r s are so dense
th a t by t h e ir a r g y r o p h ilia th e y may hamper th e i d e n t i f i c a
t io n o f n e r v e s. They may be m istaken fo r n erv es in t h in
s e c t io n s as w e ll a s m asking th e n e r v e s. T his d i f f i c u l t y
was overcome in th e p resen t stu d y by th e use o f th e
enzym es, p e p sin , t r y p s in , or pap ia n . T his tech n iq u e
removed th e c o lla g e n o u s elem en ts e ith e r c o m p letely or
p a r t ia lly w ith ou t in t e r f e r in g in th e im pregnation of
n e r v e s . I t was a ls o n oted th a t th e ground su b sta n ce
p a r t ic u la r ly in lo o s e co n n ec tiv e t i s s u e o f th e pulp o f th e
43
't e e t h where i t i s so abondant ^may p revent th e n erve f ib e r
fr o # b ein g im pregnated w ith s i l v e r . T his in te r fe r e n c e
was a ls o removed by th e use o f th e enzymes w hich d ep o ly
m erized th e ground su b sta n c e . Thus, t h i s d ig e s t io n
tech n iq u e made p o s s ib le a much more com plete d em onstration
o f th e nerve f i b e r s .
I . INGISOR
In th e in c is o r one can fo llo w th e com plete forma
t io n o f th e v a r io u s d e n ta l t is s u e s from t h e i r o r ig in to
m atu ration in one s e c t io n . W eatherford (1939) d esc r ib e d
f in e m ed u llated f ib e r s e n te r in g th e in c is o r to o th in a 12
day o ld r a t , and p a ssin g as s in g le or as sm a ll bundles
deep in to th e p u lp , t o term in a te f i n a l l y in th e odonto
b la s t ic a r e a . However, in th e m a te r ia l used in t h i s
p resen t stu d y o n ly sm a ll f ib e r s o f l e s s than 1 m icron in
d ia m eter were dem onstrated in th e p u lp , and th e s e were
alw ays c l o s e ly a s s o c ia te d w ith th e blood v e s s e l s . To
account fo r t h i s d iff e r e n c e between th e fin d in g s o f
W eatherford and th e a u th o r , c e r ta in fa c to r s must be
c o n sid e r e d . Because th e d e n tin i s b ein g c o n s ta n tly formed
throughout th e l i f e o f th e in c is o r , th e pulp and e s p e c ia l
l y th e od on togen ic zone are c h a r a c te r iz e d by th e p resen ce
o f p rec o lla g e n o u s and c o lla g e n o u s f ib e r s in term ix ed w ith
j 44
I a la r g e p lex u s ©f blood v e s s e ls # These c o lla g e n o u s e l e -
I ment8 v a ry in s i z e from th ic k wavy f ib e r s t o lo n g stran ds#
They stream in to th e pulp from th e base o f th e to o th , and
I are a ls o found in th e o d o n to b la stic la y e r , th e so c a lle d
Î Von K o r f's f i b e r s , p a r a lle lin g th e d ir e c t io n o f th e
d e n tin a l f i b e r s . I t i s ob vious th a t th e s e f ib e r s could
I e a s i l y be m istak en fo r n erv es w henever a s i l v e r im pregna-
I tio n method i s u sed , and when t h in s e c t io n s are s tu d ie d .
I
I As th e s e c o n n e c tiv e t i s s u e f ib e r s w ere d ig e s te d by th e
enzym es, i t can be con clu d ed , t h e r e f o r e , th a t th e o n ly
i s i l v e r im pregnated f ib e r s rem aining were n e r v e s . F u rth er-
! more th e s e f ib e r s w ere assumed t o be n on-m edu llated
jbecau se o f t h e i r s i z e , and th e y were c o n s is t e n t ly a s s o c i-
jated w ith th e blood v e s s e l s . T his d ir e c t a s s o c ia t io n w ith
th e v a sc u la r s tr u c tu r e s le a d s one t o th e in te r p r e ta tio n
! th a t t h e s e nerve f ib e r s o f th e pulp o f th e in c is o r are
I autonom ic in nature*
The n erv es su p p ly in g th e l a b i a l a lv e o la r p e r io s
teum are d if f e r e n t in ty p e and n a tu re from th o s e o f th e
lin g u a l p e r io d o n ta l membrane. In th e form er sm a ll non
m edulla ted n erv es were observed alw ays a s s o c ia te d i n t i
m a tely w ith blood v e s s e ls a s both tr a v e r se d th e w hole
le n g th o f th e p erio steu m . On th e oth er hand,)the lin g u a l
p e r io d o n ta l membrane co n ta in ed la r g e se n so r y nerve bundles
45
independent o f th e blood v e s s e l s . The l a b i a l a lv e o la r
p eriosteu m i s a h ig h ly v a s c u la r iz e d co n n e c tiv e t i s s u e , and
one o f i t s fu n c tio n s i s to fu r n ish an abundant blood su p p ly
d u rin g th e p ro cess o f a m e lo g e n e sis. At th e b eg in n in g o f
d e n tin o g e n e s is , th e so u rce o f blood su p p ly to th e enamel
organ, and p a r t ic u la r ly th e a m e lo b la sts, s h i f t s from th e
pulp or d e n ta l p a p illa to th e l a b i a l a lv e o la r p erio steu m .
|At t h i s tim e th e c a p i l l a r i e s and a r t e r io le s p r o lif e r a t e
land protrude in to th e a v a sc u la r enam el organ. T his
I
jr e la tio n s h ip in s u r e s a con tin u ou s h ig h m etabolism o f th e
ienamel organ during th e p ro cess o f enam el form ation when
Ia r ic h in f lu x o f n u tr ie n t su b sta n ce s t o th e a m e lo b la sts
i s r e q u ir e d . T h erefo re, i t i s n ot s u r p r is in g th a t th e
nerve su p p ly to th e l a b ia l a lv e o la r p eriosteu m i s composed
o f n on -m ed u llated n e r v e ^ fib e r s . On th e o th er hand th e
lin g u a l p e r io d o n ta l membrane a c t s as a su sp en sory ligam en t
and r e c e iv e s s t r e s s e s during th e m a stic a to r y p r o c e s s .
T h is membrane c o n s is t s o f a denser, l e s s v a sc u la r c o n n e c tiv e
t i s s u e whose r a d ia l f ib e r s a tta c h th e cementum to th e
u n d erly in g a lv e o la r bone. The nerves found in t h i s area
w ere assumed to be p ro p rec ep tiv e s in c e te r m in a ls were
observed independent o f blood v e s s e ls #
46
I I . M O LA R S
Pulp
I t has been g e n e r a lly accep ted th a t th e d e n ta l
n erve a r is e s a s a s in g le f ib e r bundle from th e a lv e o la r
n erve J , and p a sses through th e bone to e n te r d i r e c t l y
in to th e a p ic a l foramen o f th e to o th . For th e most p art
t h i s con cept was based on e ith e r g r o ss d is s e c t io n s o f
human and anim al jaws or h i s t o l o g i c a l s e c t io n s o f e x tr a c te d
t e e t h . However, in t h i s stu d y , when th e c o n tin u ity o f th e
d e n ta l nerve from i t s o r ig in t o i t s te r m in a tio n was
fo llo w e d , th e pathway proved to be s l i g h t l y d i f f e r e n t .
The d e n ta l n erv e, a f t e r i t le a v e s th e a lv e o la r n erv e ,
im m ed iately d iv id e s in to two or th r e e f a s c i c u l i th a t
tr a v e r s e th e bone t o e n te r th e a p ic a l a r e a . A fte r g iv in g
o f f th e p e r io d o n ta l membrane b ran ch es, th e s e se p a r a te
n er v e s u n ite t o form a p u lp a l n erve in th e a p ic a l foram en.
The d is t r ib u t io n o f th e n erv e s in th e pulp proper
o f th e r a t ' s m olars i s s im ila r to th e c l a s s i c a l d e s c r ip
t io n f o r human t e e t h w ith one d if f e r e n c e . N erves in th e
p r e d e n tin and d e n tin w ere n ot dem onstrated in t h i s stu d y .
T h is f in d in g i s in c o n tr a s t t o o b se r v a tio n s made on
human t e e t h (B ern iek 1948) in w hich th e author u sin g th e
47
same tech n iq u e dem onstrated n erves in th e p red en tin and
. d e n tin . Powers (1952) and o th e rs have shown s im ila r
j r e la t io n s h ip s . T h is f a ilu r e to fin d n erv es in th e p re-
' d e n tin and d e n tin in th e r a t ^s m olar may he due to v a r ia -
! t io n s between t e e t h o f d if f e r e n t s p e c ie s , or th e p o s s ib i
l i t y th a t th e age o f th e r a t s stu d ie d was such th a t th e
n erv es had not as y e t been entrapped by th e d e n tin . The
auth or in a p rev io u s p u b lic a tio n (19 4 8 ) p resen ted a t h e s i s
I t o e x p la in th e p resen ce o f n erves in th e d e n tin . In th e
1 p ro cess o f d e n tin o g e n e s is , th e o d h n to b la sts r e c e d e :in
i
I synchrony w ith m atrix d e p o s itio n . I f th e nerve f ib e r s
I
I term in a te in th e o d o n to b la stic la y e r , and th e odonto
b la s t s reced e b e fo re th e d ev elo p in g m a trix , i t i s rea so n
a b le t o assume th a t th e nerve f ib e r s co n tin u e t o pro
l i f e r a t e in order t o m ain tain t h e ir fundam ental r e la t io n -
, sh ip to th e o d o n to b la s ts . -A t some p eriod d u rin g th e
' r e c e s s io n some p o r tio n o f th e nerve may be entrapped by th e
surrounding m a trix , hence th e term in a l r e la t io n s h ip i s not
' a lt e r e d . On th e o th er hand in th e m a te r ia l s tu d ie d , th e
th ic k n e s s o f d e n tin was such th a t th e n erv es had not been
surrounded by th e d ev elo p in g p red en tin and d e n tin .
48
P e r io d o n ta l Membrane
P rev io u s in v e s t ig a t io n s on th e in n e r v a tio n o f th e
p e r io d o n ta l membrane are n o tic e a b ly few in number compared
w ith th o s e on th e in n e r v a tio n o f th e pulp and d e n tin .
These few e a r lie r works by Dependorf (1 9 1 3 ), Ton der
S pren kel (1 9 3 6 ), K adnoff (1933) w ere m ainly concerned w ith
th e mode of branching and f i n a l te r m in a tio n s o f th e n erv es
in th e p e r io d o n ta l membrane o f th e t e e t h o f man, c a t s ,
sheep and o th er mammals. They n e g le c te d to fo llo w th e
o v e r a ll n erve d is t r ib u t io n t o th e membrane s in c e th e y
to o k fo r granted th a t th e n erve su p p ly i s s im ila r in
r e la t io n in a l l th e e x te r n a l su r fa c e s o f th e t o o t h . T h eir
b e l i e f was based on th e c l a s s i c a l d e s c r ip tio n s th a t w ere
d eriv ed from f in e g ro ss d is s e c t io n s of human and o th er
anim al jaw s. -According t o t h i s a ccep ted account th e
n erv es fo llo w th e blood v e s s e ls through th e in t e r a lv e o la r
and in te r r a d ie u la r bones and g iv e o f f p e r fo r a tin g branches
jthat e n te r th e membrane a t v a r io u s l e v e l s to jo in w ith
'the branches o r ig in a tin g from th e d e n ta l n e r v e . However,
!
in th e r a t a sy ste m a tic stu d y o f each o f th e s u r fa c e s has
shown th a t th e in terp ro x im a l area d i f f e r s in i t s nerve
.supply from th e o th e r s u r fa c e s . The s ig n if ic a n t d iff e r e n c e
lis th e ab sen ce o f in t e r s e p t a l n erv es and t h e ir p e r fo r a tin g
49
b ran ch es. The m e sia l su r fa c e o f one to o th and th e d i s t a l
su r fa c e of th e a d ja c en t to o th have independent n erv es
w hich pass th e w hole le n g th o f th e membrane w ith o u t r e
c e iv in g r e in fo r c e m e n ts. These in d iv id u a l n erv es form a
combined network above th e a lv e o la r c r e s t in th e tr a n s -
s e p t a l f ib e r s and co n tin u e g in g iv a lly t o su p p ly th e s o f t
t i s s u e a r e a . The o th er e x te r n a l s u r fa c e s are su p p lie d
in th e c l a s s i c a l manner d e sc r ib e d ab ove.
G ingivae
The main problem o f g in g iv a l in n e r v a tio n i s
I
w hether or n ot th e g in g iv a e are h ig h ly s e n s i t i v e o rg a n s.
To d iscu ss t h i s su b ject various asp ects must be considered.
The q uestion of whether the gingivae are r ic h in in tr a -
Ipapillary and in tr a e p ith é lia l nerves has been argued for
I
isome tim e . K adnoff (19 2 9 ), Stew art and Lewinsky (1 9 5 8 ,
1 9 3 9 ), Bradlaw (1 9 3 6 , 1939) and G airns and M t oh in s on
j( 1950) have t r ie d t o show th a t th e g in g iv a e are r ic h in
in tr a p a p illa r y and in t r a e p i t h e l i a l n e r v e s, but Radden
(19 45) in h is attem pt t o confirm th e r e s u l t s o f th e s e
in v e s t ig a t o r s was d isa p p o in te d when he f a ile d t o show a s
g r e a t a number o f in tr a p a p illa r y and in t r a e p i t h é l i a l n erv es
a s d id h is p r e d e c e s s o r s . T h is i s not s u r p r is in g s in c e th e
above in v e s t ig a t o r s came t o t h e ir c o n c lu sio n s on stu d y in g
is o la t e d g in g iv a l s e c t io n s w ith o u t regard to s p e c i f i c d i v i
s io n s o f th e g in g iv a . When th e y id e n t if ie d n erv es in th e
c o n n e c tiv e t i s s u e p a p illa e or in th e ep ith e liu m o f th e
specim ens s tu d ie d , th e y assumed th a t th e w hole g in g iv a was
e q u a lly r ic h in n e r v e s. T h is i s u nd erstan d able as th ey
were g r e a tly in flu e n c e d by c l a s s i c a l d e s c r ip tio n s o f c u ta
neous in n e r v a tio n by G ajal (1928) and Boeke (1 9 3 2 ). These
d e s c r ip tio n s were based m ainly on p rep a ra tio n s o f th e sk in
taken from th e sn oot and m uzzles o f mammals and th e fin g e r
or s o le s o f th e f o o t , th a t i s , r e g io n s o f th e sk in in
w hich th e se n so r y in n e r v a tio n i s p a r t ic u la r ly abundant.
On th e o th er hand a few more r e c e n t s t u d ie s by Kuntz and
H am ilton (1938) and W ollard (1 9 3 7 , 1940) on cutaneous
a rea s o f l e s s e r s e n s i t i v i t y r e v e a le d a s c a r c it y o f in t r a -
é p i t h é l i a l n erv es and s p e c ia liz e d nerve e n d in g s. These
in v e s t ig a t o r s a ls o b e lie v e d th a t th e cu taneous r e g io n s
c o n ta in in g w e ll d evelop ed p a p illa e are r ic h ly in n erv a ted
w hereas th o s e r e g io n s o f th e sk in c h a r a c te r iz e d by p o o rly
formed or no p a p illa e have a l e s s abundant in tr a p a p illa r y
and in t r a e p i t h é l ia l in n e r v a tio n . In t h i s p resen t in
v e s t ig a t io n when th e nerve su pp ly to th e in ta c t g in g iv a
was tr a c e d , i t was found th a t th e g in g iv a l in n e r v a tio n
g e n e r a lly i s s im ila r to th a t o f th e cu taneous a rea s o f
51
l e s s e r s e n s i t i v i t y . A few n erv es were seen e n te r in g th e
G onneetive t i s s u e p a p illa e or e p ith e liu m . These n erv es
a ro se from netw orks in th e tu n ic a p r o p r ia . However, th e se
were lo c a te d in r e g io n s th a t are c h a r a c te r iz e d by w e ll
I d evelop ed p a p illa e such as th e in te rp ro x im a l and th e
j a tta ch ed g in g iv a e . O n th e o th er hand th e o th er d iv is io n s
I o f th e g in g iv a e , such a s th e m arginal g in g iv a and th e
I
I e p i t h e l i a l a tta ch m en t, Which are poor in or la c k p a p illa e
I
I are m ain ly in n erv a ted by term in a l netw orks found in th e
!
I tu n ic a p ro p ria . M o f ib e r s p ass in to th e e p ith e liu m .
I Another rea so n fo r th e d iff e r e n c e in th e fin d in g s
I on g in g iv a l in n e r v a tio n may be in th e co n fu sio n in th e
I i d e n t i f ic a t i o n o f n erv es and c o lla g e n o u s f i b e r s . A gain
I one must remember th a t th e g in g iv a i s r ic h in a r g y r o p h ilio
f ib e r s o th er than n e r v e s . These a r is e from th e cementurn
and a lv e o la r bone to r a d ia te in a l l d ir e c t io n s in t o th e
g in g iv a b efo re te r m in a tin g in th e p a p illa e . T hese are lo n g
and v ary in d iam eter from t h ic k f ib e r s t o t h in str a n d s .
j
! Such lo n g f ib e r s cou ld e a s i l y be m istaken fo r n erv es when
ever t h in s e c t io n s w ith o u t d ig e s t io n are u sed . The p o s s i-
j b i l i t y o f m is in te r p r e ta tio n o f c o lla g e n o u s f ib e r s as n erv es
jm ight lea d one t o th e b e l i e f th a t th e p a p illa r y a rea s are
I r ic h in n e r v e s. However, by th e use o f t h ic k s e c t io n s and
52
d ig e s t io n w ith enzymes th e p resen t stu d y shows th a t few
p a p illa e con tain ed n e r v e s.
The f i n a l fa c to r t o be d isc u sse d i s th e ty p e o f
n erve en d in gs in th e g in g iv a . The r e p o r ts o f th e e a r lie r
m entioned in v e s t ig a t o r s in d ic a te d g rea t v a r i a b i l i t y and
co m p lex ity in th e p e r ip h e r a l nerve en d in g s. They have
been d esc rib e d as en ca p su la ted en d ings such as K rause’s
and M e issn er’s , n on en cap su lated en d in gs such a s c lo s e
c o i l s and f r e e lo o s e c o i l s , and f i n a l l y f r e e nerve en d ings
lo c a te d in th e c o n n e c tiv e t is s u e p a p illa e and e p ith e liu m .
W oollward (1 9 3 5 , 1936) and Tower (1943) have shown th a t
in c e r ta in a re a s o f th e sk in and cornea nonm edullated
f ib e r s break up in to p reterm in a l form s such a s tw ig s ,
knobs, lo o p s , b ru sh es, or s k e in s in th e tu n ic a propria and
even in th e p a p illa e . From t h e s e p le x u se s f in e f ib e r s
I emerge t o become th e f r e e en d in gs in th e tu n ic a propria
i
; or e p ith e liu m . T h is r e la t io n s h ip i s found in th e tu n ic a
; p rop ria o f th e g in g iv a e o f th e r a t s s tu d ie d . At no tim e
I w ere th e r e in d ic a t io n s o f en ca p su la ted en d in gs or non-
; en ca p su la ted c o ile d ty p e s . The cla im s o f th e occu rren ce
o f th e en ca p su la ted or n onenoap su lated en d ings may be due
^to m isin t è r p r ê t â t io n o f t h in s e c t io n m a te r ia l. I t i s not
!
I hard to v is u a liz e th a t th e s e p reterm in a l tw ig s , b ru sh es,
I
I or lo o p s may g iv e a f a l s e appearance o f c o i l s or even
53
en ca p su la ted n erve en d in gs in t h in s e c t io n s o f 15 mi era or
l e s s . At t h is th ic K n ess o n ly sm all fragm ents o f th e lo o p s
or b rushes would be v i s i b l e in s in g le s e c t io n s and could
e a s i l y be m istaken fo r f i n a l s p e c ia liz e d te r m in a tio n s.
The ab sen ce o f s p e c ia liz e d nerve en d in g s i s not
!
: s u r p r is in g fo r in th e l e s s s e n s i t i v e a r e a s o f th e sk in and
I mucous membranes, i t i s ra r e t o fin d t h e s e s tr u c t u r e s .
! B ishop (1949) p o in ts out th a t a f r e e ending w hich ca u ses
p ain i f th e s k in i s p rick ed may g iv e r i s e , when stim u la te d
: e l e c t r i c a l l y , to a s e r i e s o f d if f e r e n t s e n s a t io n s . S o,
I
I in th e g in g iv a w hich has t o w ith sta n d th e fo r c e s o f m a s ti-
I c a t io n , th e fr e e nerve en d in gs w hether in th e e p ith e liu m or
I s u b e p ith e lia l c o n n e c tiv e t i s s u e may n orm ally g iv e r i s e not
I o n ly t o p ain but o th e r s e n s a t io n s .
CHAPTER VI
SIBMRY
.. The in n e r v a tio n o f th e d e n tit io n and periodontium o f
th e r a t was stu d ie d by th e P ea rso n ’s s i l v e r impregna
t io n method* The jaws and t e e t h were fix e d in a form ol
a c e t ic a c id a lc o h o l m ix tu re, d e c a l c i f i e d , dehydrated
and embedded in n it r o c e llu lo s e in th e u su a l manner*
The jaws and t e e t h w ere s e c tio n e d a t 25-100 mi era#
* The n erve su p p ly t o th e pulp o f th e in c is o r s c o n s is t s
o f nonm edullated n erve f ib e r s which w ere alw ays
in tim a te ly a s s o c ia te d w ith blood v e s s e ls throughout
t h e ir course* T h is d ir e c t a s s o c ia t io n w ith blood
v e s s e ls le a d s one to th e assum ption th a t th e n erv es in
th e pulp o f th e in c is o r are autonom ic in nature*
3* The n erv es to th e l a b i a l a lv e o la r p eriosteu m o f th e
I
i in c is o r d i f f e r in n atu re from th o se o f th e lin g u a l
p e r io d o n ta l membrane. In th e form er o n ly nonm edullated
!
j n erve f ib e r s were se e n accompanying th e blood v e s s e l s .
I
i On th e o th er hand som atic a f fe r e n t f ib e r s w ere observed
I throughout th e lin g u a l p e r io d o n ta l membrane. These
term in a te among th e stroma c e l l s o f th e membrane.
4 . In p u lp a l in n e r v a tio n o f th e m o la rs, th e d e n ta l nerve
55 I
a r i s e s from th e a lv e o la r nerve t o d iv id e in to two or {
th r e e f a s c i e u l i w hich tr a v e r s e the^hone and r e u n ite I
in the a p ic a l foramen o f th e r o o t o f th e t o o th .
5 . The co ro n a l p o rtio n o f th e pulp o f th e m olars i s in
n erv a ted in th e same manner as human m olars ex cep t fo r
one d if f e r e n c e , nam ely, no ter m in a l n erv e s were ob serv
ed e n te r in g th e p red en tin and d e n tin .
6 . The n erve su p p ly to th e p e r io d o n ta l membrane a r is e s
from th e d e n ta l and in te r a lv e o la r branches o f th e
a lv e o la r n e r v e s. The d e n ta l nerve f ib e r s su p p ly th e
p e r ia p ic a l area and p ass g in g iv a lly t o form a network
w ith th e p e r fo r a tin g branches which o r ig in a te from th e
in t e r a lv e o la r n e r v e s.
7 . The n erv es term in a te as " free nerve endings" among th e
c e l l s o f th e p e r io d o n ta l membrane, th e c e m e n to b la stic
la y e r , and th e cementurn p rop er.
8 . G in g iv a l in n e r v a tio n i s d eriv ed from two so u rc es;
(1 ) f ib e r s a r is in g from th e n erv es o f th e p e r io d o n ta l
membrane and (2 ) f ib e r s o r ig in a tin g from th e l a b ia l
or p a la t a l n e r v e s . As th e s e f ib e r s p ass through th e
c o n n e c tiv e t i s s u e o f th e g in g iv a e , term in a l branches
are g iv e n o f f th a t su p p ly th e tu n ica p ro p ria . I n tr a -
p a p illa r y and in t r a e p i t h é l i a l n erve en d in gs are s c a r c e .
56
9 . No s p e c ia liz e d n erve en d in g s such a s K rause’s or
M e issn er ’s c o r p u sc le were seen in e it h e r th e p e r io
d o n ta l membrane or g in g iv a e .
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I I . PERIODONTAL M E M B R A N E A N D GINGIVAL INNERVATION
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1948 In n e rv a tio n o f th e human to o th . A nat. Reo.
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1949 R e la tio n o f pain se n so r y th r e sh o ld to forms of
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1929 Nerven und N er v en v erteilu n g in der Zahnwurzelhaut;.
V erhandl. d . p hys. med. G e s e lls c h . V o l. 5 4 , 2 7 -3 2 .
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1929 Ueber d ie N erven versorg ung d es m en sohlich en
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8 8 1 -8 9 2 .
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1938 A ffe r e n t in n e r v a tio n o f th e s k in . A nat. R ec.
V o l. 71, 3 8 7 -4 0 0 .
Lew insky, W . and S te w a r t, D.
1936 In n e rv a tio n o f th e p e r io d o n ta l membrane.
J . A nat. V o l. 7 1 , 98-:
Lew insky, W. and S te w a r t, D.
1937 The in n e r v a tio n o f th e p e r io d o n ta l membrane of
th e ca t w ith some o b se r v a tio n s on th e fu n c tio n o f end
organ found in th e s tr u c tu r e . J . A nat. V o l. 71,
2 3 2 -2 3 5 .
Lew insky, W , and S te w a r t, D.
1938 In n e r v a tio n o f human gum. J . A nat. V o l. 72,
5 3 1 -5 3 4 .
Lew insky, W . and S te w a r t, D.
1939 A com parative stu d y o f th e in n e r v a tio n o f th e
gum. P roo. R oyal S o c. Med. V ol. 3 2 , 1 0 5 4 -1 0 6 2 .
Von der S p ren k el, H. B.
1936 M ic ro sco p ica l in v e s t ig a t io n s o f th e in n e r v a tio n
o f th e to o th and i t s su rro u n d in g s. J . A nat. V o l. 71,
233-241#
68
I I I . MISCILLAHSOUS
Boeke, J .
1952 Nerve E n d in gs. Motor and S en so ry . C y tology and
C e llu la r P a th o lo g y o f th e Nervous System . P. B.
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sy stem . Oxford U n iv e r s ity P r e s s , O xford, England.
4 1 4 -4 6 4 .
C a irn s, F. W . and J . A. A ito h iso n
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en d in gs in th e human gum. D en ta l R ecord. V ol. 70,
1 8 0 -1 8 6 .
Pow ers, M. M.
! 1952 The s t a in in g o f n erve f ib e r s in t e e t h . J n l.
; o f D en t. R es. V ol. 3 1 , 3 8 3 -3 9 2 .
' Radden, H. C.
1945 O b servation s on th e p e r ip h e r a l n erve en d in gs o f
th e human o r a l m icro p erio steu m . A u st. J n l. o f D ent.
V o l. 7 2 , 1 - 7 .
Tow ers, S . S .
1943 P a in , d e f i n i t i o n and p r o p e r tie s . P roc. A ssn.
fo r R es. in Nervous and M ental D is e a s e . V o l. 23,
1 6 -4 3 .
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1935 O b servations on th e te rm in a tio n s o f cu taneous
n e r v e s . B rain . V o l. 5 8 , 3 5 2 -3 6 7 .
W oollward, H. H.
1936 In tr a -e p id e rm a l n erve en d in g s. J . A nat. V o l.
7 1 , 5 4 -6 0 .
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1937 C o n tin u ity in n erve f i b e r s . J . A nat. V ol. 71,
4 8 0 -4 9 1 .
W oollward, H. H.
1940 O b servation s on th e n e u r o h is to lo g ic a l b a s is o f
cu taneous p a in . J n l. A nat. V o l. 75, 3 6 0 -3 6 5 .
Î>LATBS
70
ABBREVIATIONS USED
AB s A lv e o la r bone
A C r A lv e o la r Greet
a r t . ® A r t if a c t
B z Bone
BV « Blood v e s s e l
C z Cement u r n
OF z C ollagen ou s f ib e r s
D s D en tin
DN s D en tal nerve
EA s E p it h e lia l attachm ent
E z E p ith eliu m
E O s Enamel organ
En. = Enamel
G = G ingiva
GE z G in g iv a l e p ith e liu m
La. z Labium
La. AB 5 L a b ia l a lv e o la r bone
La.. AP = L a b ia l a lv e o la r p eriosteu m
L i. AB = L in gu al a lv e o la r bone
L i. PM z L in gu al p e r io d o n ta l membrane
M s Marrow
N : Nerve
Na. B N asal branches o f a n te r io r
su p e r io r a lv e o la r nerve
71
NE = Nerve ending
P c . = P r e c o lla g e n o a s f ib e r s
T f = T ra n ssep ta 1 f ib e r s
72
PLATE I
E xp lan ation o f F ig u res
F ig u res 2-16 are a c tu a l unretouched photom icrographs
o f t h ic k h i s t o l o g i c a l s e c t io n s . A ll th e s e c t io n s re p r e
sen ted by th e photom icrographs ex cep t th a t o f fig u r e 2
i»ere im pregnated by P ea rso n ’ s s i l v e r g e la t in m ethod.
F ig . 1 . Schem atic drawing o f th e t e e t h and periodontium
o f th e r a t s upper and low er jaw s. The numbers
re p r e se n t th e a rea s from which th e photo
m icrographs were ta k en .
PLATS I. 73
a . A . B .
L O . A . R
L i . R M ,
i . Æ B .
8.
b.iqt: 9.
74
PLATE I I
F ig . 3 . S a g i t t a l s e c t io n o f an upper in c is o r . (R efer to
area 2 o f F ig . 1 .) Observe th e r e la t io n s h ip of
th e l a b i a l a lv e o la r p eriosteum to th e enamel
organ* Note th e o r ie n ta tio n o f th e co lla g e n o u s
f ib e r s in th e l a b i a l a lv e o la r p erio steu m .
H em atoxylin and t r io s in * X 390*
75
P L A T E II
mm
76
PLATE I I I
Fig* 3 . A s e c t io n o f th e lin g u a l p e r io d o n ta l membrane.
(R efer to area 3 o f F ig , 1 .) The lin g u a l
p e r io d o n ta l membrane nerve i s seen e n te r in g th e
membrane and d iv id in g in to i t s main b ran ch es.
The s e c t io n was n ot d ig e s te d by p ep sin and
t r y p s in . C on trast t h i s s e c t io n w ith th a t o f
F ig . 4 . X 390.
P L A T E III
77
78
PLATE IV
F ig , 4 , A s e c tio n of the lin g u a l p eriod on tal membrane of
an upper in c is o r . (R efer to area 4 of F ig . 1 .)
The p o ste r io r d iv is io n of the lin g u a l p e r io
d o n ta l membrane nerve i s g iv in g o f f term inal
branches as i t courses towards the odontogenic
pulpal zone of the in c is o r . Note th e recu rren t
p erfo ra tin g nerves en terin g the bone. The
s e c t io n was d ig e ste d by pepsin and tr y p sin w ith
consequent lo s s of th e collagen ou s elem en ts.
X 390.
P L A T E IV
79
*A rp'^
80
PLATS V
F ig . 5. A s e c tio n o f th e odontogenic pulpal zone of an
upper in c is o r . (R efer t o area 5 of F ig . 1 .)
Nerves are seen a sso c ia te d w ith the blood v e s
s e l s . Note th e absence of a la r g e nerve bundle.
Non-nervous a r g y r o p h ilic fib e r s ( P c . ) are
p resen t, and th e se may be m istaken fo r n erv es.
The s e c t io n was not exposed to the a c tio n of
pepsin and tr y p s in . X 390.
81
P L A T E V
t i
83
PLATS VI
F ig , 6 . A s e c tio n o f th e l a b ia l gin giva of an upper
in c is o r . The nerve supply to t h i s re g io n
o r ig in a te s as ex ten sio n s of nerves d erived
from th e n a sa l and l a b i a l branches o f th e
a n te r io r su p erior a lv e o la r nerves* S e c tio n
was d ig e ste d w ith pepsin and tr y p s in . X 390.
P L A T E VI
83
X
.♦ T ; O
I f . -< •
84
PLATE 711
F ig . 7. A s e c tio n of the a p ic a l area of the d i s t a l root
of an upper f i r s t m olar. (R efer to area 7 of
F ig. 1.1 Two nerve f a s c i c u l i are seen
p assin g through the underlying hone t o u n ite
as one pulpal nerve in the a p ic a l foramen of
the r o o t. Note th a t each fa s c ic u lu s g iv e s o ff
a branch to the p eriod on tal membrane known as
th e d en ta l branch of the p erio d o n ta l membrane
n erves. The s e c tio n was d ig e ste d by pepsin and
tr y p s in . X 390.
P L A T E VII
85
S
86
PLATE VIII
F ig . 8. A s e c tio n of the pulp of an upper f i r s t m olar.
(R efer to area 8 of F ig. 1 .) This s e c t io n
was not trea ted w ith pepsin and tr y p s in . The
pulp i s composed o f a lo o se con n ective t is s u e ;
con sequen tly i t appears pale w ith the s i l v e r
im pregnation. The absence of a d e f in i t e nerve
p lexus in th e pulp i s due to the masking by
both the collagen ou s elem ents and ground
su b stan ce. Compare t h i s s e c t io n w ith fig u r e 9 .
X 390.
P L A T E VIII
87
i
88
PLATE IX
F ig. 9. A s e c tio n of the pulp of an upper f i r s t m olar.
(R efer to area 9 o f F ig. 1 .) This s e c t io n was
exposed to the a c tio n of pepsin and tr y p sin
before th e s i l v e r im pregnation. The d ig e s tio n
p rocess has com p letely removed the collagen ou s
elem ents and a ls o depolym erized the ground
substance thus making v i s i b l e im pregnation of
the apparent t o t a l nerve d is t r ib u t io n to the
pulp of th e m olar. X 390.
PI.ATE IX
89
90
PLATE X
F ig . 10. A s e c tio n of the p erio d o n ta l membrane o f th e
in terp rozim al area between two adjacent upper
m olars. (R efer to area 10 of F ig , 1 ,) An
in terp roxim al nerve i s seen passing towards th e
gin giva and g iv in g o f f branches in i t s cou rse.
Note the absence o f th e in t e r s e p t a l n erves
and t h e ir p erfo ra tin g branches in th e bone.
The s e c tio n was d ig e ste d by pepsin and tr y p s in .
X 390.
P L A T E X
91
y
93
PLATE XI
F ig . 11. The p eriod on tal membrane of the d i s t a l su rface
o f an upper th ird m olar. (Refer t o area 11
of F ig. 1 .) Two p erfo ra tin g n erves are
observed a r is in g from th e in te r a lv e o la r region
to en ter the p erio d o n ta l membrane and u n ite
w ith th e ascending d e n ta l nerve to form a
common bundle which con tin u es g in g iv a lly . The
s e c t io n was p a r t ia lly d ig e ste d by the a c tio n
of pepsin and tr y p s in . X 390.
P L A T E XI
93
I
X
!
»
94
PLATE XII
F ig . 12. A s e c tio n of the p erio d o n ta l membrane of th e
m esia l su rfa ce of an upper f i r s t m olar.
(R efer to area 12 of F ig. 1 .) A nerve (N) i s
observed term in atin g at the cem en tob lastic area.
Note th e knoblike nerve endings (NE) in the
stroma of the p eriod on tal membrane. The
s e c t io n was d ig e ste d by pepsin and tr y p s in .
X 390.
P L A T E ZII
95
S
96
PLATE X III
P ig . 13. The in terp roxim al gin giva between two adjacen t
m olars. (R efer to area 13 of P ig. 1 .) The
nerve su pplyin g t h i s region o r ig in a te s as an
e x te n sio n o f the p eriod on tal membrane n erv es.
The term in al branches v i s i b l e in t h i s reg io n
are lo ca ted in the tunica propria and th e
s u b e p ith e lia l zone. The s e c tio n was d ig e ste d
by pepsin and tr y p s in . X 390.
97
P L A T E XIII
>
^ ' î « ‘
M
m
98
PLATE XIV
F ig . 14. A s e c t io n o f th e g in g iv a l area o f the d i s t a l
su rfa ce o f the upper th ir d m olar. (R efer to
area 14 o f F ig . 1 ,) The main nerve supply to
t h i s area o r ig in a te s as ex ten sio n s o f both
the p eriod on tal membrane nerves and p a la ta l
n erv e s. Observe a la r g e branch p assin g
towards the g in g iv a l ep ith eliu m and appearing
to en ter t h is la y e r . The s e c tio n was d ig ested
by pepsin and tr y p s in . X 390.
P L A T E XIV
99
m m #
100
PLATE XV
F ig . 15. A s e c tio n o f the gin giva from th e d i s t a l
su rfa ce of an upper th ir d m olar. (Refer to
area 15 of F ig. 1 .) The nerves are seen
term in atin g in th e tun ica propria and sub-
e p i t h e l i a l reg io n as fr e e nerve en d in gs. Note
the absence of s p e c ia liz e d nerve endings such
as K rause’s or M eisnner’s . S ectio n was
d ig e ste d by pepsin and tr y p s in . X 390.
P L A T E X V
1 0 1
102
PLATE XVI
F ig . 16. A s e c tio n of a ruga of the p a la te . A la r g e
nerve f a s c ic u lu s i s seen a r is in g from th e
main p a la tin e nerve and p assin g towards the
apex of the ruga. At th e apex th e fa s c ic u lu s
ra m ifie s in to a network from which term in al
fila m en ts o r ig in a te to en ter the e p i t h e l i a l
la y e r . The s e c tio n was d ig e ste d by pepsin and
tr y p s in . X 390.
P L A T E X7I
103
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Creator Bernick, Sol (author)

Core Title The innervation of the teeth and periodontium of the rat

School Graduate School

Degree Doctor of Philosophy

Degree Program Anatomy

Degree Conferral Date 1955-06

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag anatomy,biology,OAI-PMH Harvest

Language English

Contributor Digitized by ProQuest (provenance)

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c30-204044

Unique identifier UC11227212

Identifier DP23582.pdf (filename),usctheses-c30-204044 (legacy record id)

Legacy Identifier DP23582.pdf

Dmrecord 204044

Document Type Dissertation

Rights Bernick, Sol

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the au...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus, Los Angeles, California 90089, USA