THE DECOMPOSITION OF THE CONTENTS OF THE DEN- 
TINAL TUBULES AS A DISTURBING FACTOR IN THE 
TREATMENT OF PULPLESS TEETH. 
W. D. MILLER, PH.D., D.D.S., BERLIN. 
(Reprinted from the Dental Cosmos for May, 1890.) 
In many of the recent discussions on the treatment of pulpless 
teeth or teeth with foul pulps, particular stress has been laid upon the 
supposed necessity of pursuing such a course of treatment as will bring 
about a complete sterilization of the contents of the tubuli in the den- 
tine of the root. It has been claimed that otherwise decomposition 
of such contents will follow, gases and other products of putrefac- 
tion will work their way through the dentine and cement and keep 
up a perpetual bombardment upon the pericementum, resulting in 
chronic or possibly acute inflammation of the same. 
These claims do not appear to me to be in accord with clinical ex- 
perience, nor are they, as far as my knowledge of the literature of the 
subject goes, based upon experimental evidence. It has been my ex- 
perience that in all cases where we have a straight wide canal, so that 
we can remove all traces of the pulp and thoroughly cleanse the canal, 
regardless of the tubuli, we may count upon success with almost, if not 
quite, absolute certainty. 
In proportion as the canal becomes narrower and tortuous, render- 
ing the thorough cleansing difficult or impossible, in the same degree 
the probability of a successful treatment will be diminished. It is a 
matter of continual experience that an inflammation of the pericemen- 
tum, either acute or chronic, will disappear with astonishing rapidity 
upon the total extirpation of the putrid pulp and application of almost 
any antiseptic, which would scarcely be the case if the decomposition 
of the contents of the tubuli were an important factor in the disturb- 
ance. Again, in all cases where trouble has arisen after treatment I 
have been able to trace it either to irritation of the periapical tissue by 
careless treatment or over-treatment, or to an imperfect cleansing of 
the canal. 
What, however, from a clinical aspect seems to tell most strongly 
against such a view is the fact that trouble subsequent upon filling 
occurs invariably first at the point of the root, where it may remain 
localized or spread to a greater or less portion of the pericementum, 
whereas any trouble arising from the decomposition of the contents 
of the tubuli we should expect to begin near the neck of the tooth, 
where the decomposition must first take place, if at all, and where, on 
account of the thinness of the cement,-the gases might most easily 
penetrate to the perice nj^jaJ.util„ —-—: 
Dr. N. S. Jenkins |d ei^r^^cupon! this subject as 
follows : “It is my pericemen- 2 
turn takes place when the pulp has been thoroughly extirpated, and 
the canal, pulp-chamber, and crown cavity properly filled. I have 
never known a case where there was any reason to suspect pericemen- 
tal inflammation to be caused by the decomposition of the contents of 
the dentinal tubules. The inflammation could always be more reason- 
ably accounted for, it invariably seeming to be the result of defective 
manipulation or of pre-existing necrosis.” 
It is not my intention, however, to discuss this problem from a 
clinical point of view, but rather to give the results of a few investiga- 
tions of a scientific nature which I have made in reference to this ques- 
tion, and the conclusions which may be drawn from them. 
In the first place, we must bear in mind that the only decomposition 
which could take place in the dentinal tubules is one which might be 
brought about by bacteria ; in other words, putrefactive decomposition, 
or simply putrefaction. In the event of such a decomposition of the 
contents of the tubuli taking place, a great variety of substances might 
be produced, chiefly, however, ammonia (NH,), sulphuretted hydrogen 
(SH2), hydrogen (H), carbonic acid (Co2),a variety of acid and alka- 
line substances such as formic, lactic, acetic, and butyric acids, car- 
bonate of ammonia, propylamine, trimethylamine, etc., and finally 
the ptomaines. 
It must not be supposed, however, that all these substances would 
be produced in any one case. How many of them might be formed 
would depend upon whether it were a pure or a mixed infection,—i.e., 
whether the tubules had been invaded by one or more kinds of bac- 
teria. 
The products of decomposition arising from the action of a single 
kind of bacterium are, according to the few observations yet made, 
limited in number, stinking gases being most frequently represented, 
then peptone, ammonia, trimethylamine. 
Nor should it be taken for granted that the quantity of gas pro- 
duced in a case of putrefaction must necessarily be very great; as a 
rule it is insignificant when compared with the amount of gas produced 
by the fermentation of carbohydrates. 
Bearing in mind that the putrefaction of the contents of the tubules 
can take place only under the action of micro-organisms, naturally the 
first question to be answered is, Whether and to what extent do micro- 
organisms from the root-canal penetrate the dentinal tubules ? 
At first thought the probability of an extensive invasion of the 
tubuli does not appear very great. The diameter of the normal tubuli, 
particularly in the root, is, it is true, considerably greater than that of 
most bacteria, so that on this score there would be nothing to prevent 
their entrance. It has been found, however, that the putrid dental 
pulp is often devoid of micro-organisms. This condition is not diffi- 
cult to account for, because we know that all the nourishment con- 3 
tained in a pulp may soon be exhausted, and where the pulp-chamber 
is closed so that no fresh material is admitted from without, the micro- 
organisms may perish from want of nourishment, or they may be de- 
vitalized by the prolonged action of their own products. These two 
causes would also operate in a much higher degree in the narrow 
tubuli of the dentine. Add to this the fact that the access of air must 
be exceedingly limited, so that the aerobic bacteria could probably not 
live in the tubules for any length of time, and I think we would be 
justified, a priori, in regarding the tubules of sound dentine as not 
particularly favorable media for the cultivation of bacteria. 
These are, however, only theoretical considerations ; the question 
as to whether an invasion of the tubules actually takes place or not can 
be settled by microscopical examination alone. 
With this object in view I prepared sections of nineteen roots, all of 
which, with one exception, contained remains of putrid pulps, while 
four of them were abscessed. 
The roots were sawed into lamellae about one millimeter* thick and 
placed in a ten per cent, solution of hydrochloric or nitric acid, in which 
they became softened in a few hours. They were then soaked in 
water (repeatedly changing) to remove the acid, cut on the freezing 
microtome, stained by the Gunther modification of the Gram method, 
and mounted in the usual manner in Canada balsam. 
The examination of these sections revealed in many of them a con- 
dition which, while being well known to be the normal condition in the 
tusks of elephants, for example, has not, I believe, attracted attention 
in the human teeth. 
In ten of the roots examined I found the canal to be completely or 
partially lined with a substance of a homogeneous or globular struc- 
ture, containing very few or no canals but occasionally a formation 
resembling a bone-lacuna, and on the whole bearing much more re- 
semblance to cement than to dentinef (Fig. i). This layer is imper- 
meable to micro-organisms, and acts, therefore, as a safeguard against 
the decomposition of the contents of the tubuli. 
Open roots which serve as retaining centers for food-particles 
undergo the natural process of decay, by which the lumen of the 
canal is gradually increased. The phenomena of decay here are the 
same as those in decay of the dentine of the crown and neck of the 
tooth. A cross-section under low power is given in Fig. 2. 
A microscopical examination of the sections prepared as above stated 
gave the following results : 
No. 1. Section near open end of root showed decay and extensive 
infiltration of the tubules ; section near apex appeared lined with the 
* One millimeter equals about A inch. 
t The capacity of the pulp to form other structures than dentine will he dij» 
cussed in my articles on the tusks of the elephant, 4 
impermeable modified dentine, except at one point, where a few cocci 
may be seen in eleven of the tubules. 
No. 2. Two sections from near the middle of the root ; both show 
the modified dentine. In one piece four tubules are infected, in the 
other none. 
No. 3. Sections near the open end of the root show decay ; those 
near the apex are lined on one side of the canal by impenetrable 
modified dentine’without tubules ; on the other side four tubules con- 
tain a few cocci. 
No. 4. Inner layer again destitute of tubules ; no infiltration what- 
ever. (See Fig. 1.) 
Fig. i. 
Fig. i.—Portion of a cross-section of a root containing the remains of a putrid pulp, a, root- 
canal ; b, modified impenetrable dentine lining the canal; c, normal dentine. No trace of 
infection. 
No. 5. Section near open end decayed ; section near apex shows 
about one-fourth of the canals infected with straggling cocci to a depth 
of one-fourth to one-half millimeter. 
No. 6. The end section is slightly decayed and correspondingly in- 
fected. The section near the apex is protected on one side by tube- 
less dentine ; on the other side eighteen tubules are infected by a few 
straggling bacilli to a depth of one-half to three-fourths millimeter 
(Fig. 3). A few of the tubules contain also cocci (Fig. 3, a, b), from 
which we must conclude either that the dentine is infected with two 
kinds of bacteria or with a pleomorphous bacterium. 
No. 7. The root in this case contained an inflamed pulp ; no trace 
of tubular infection is anywhere to be discovered. 
No. 8. Section from about middle of root ; twenty-six of the tubules 
are infected with cocci to a depth of about one-tenth millimeter. (See 
Fig- 4-) 5 
No. 9. The sections show again that the canal is in part lined with 
modified dentine. In two or three tubules only was I able to find 
about a dozen bacteria. The root was abscessed. 
Fig. 2.—Cross-section of the posterior root of a lower molar, showing the advance of decay 
from the canal. 20 :1. 
No. 10. The canal was found filled with masses of bacteria (see 
Fig. 5), but no infection of the tubules worth mentioning could be 
detected, only a few cocci being visible in three or four tubules. The 
canal was again partly lined with modified dentine, Root abscessed. 6 
No. ii. Abscessed root. Section near the pulp-chamber shows 
nearly all the tubules infected to the depth of one-tenth to one-fourth 
millimeter. Section near apex free from infection. 
No. 12. Ground section from near the middle of the root; no infec- 
tion of the tubules whatever. 
Nos. 13 and 14. Both partially protected by modified dentine, and 
both free from infection. 
No. 15. Canal lined by a layer of modified dentine one-fourth milli- 
meter thick. No micro-organisms visible in any of the tubules. 
No. 16. Section from about the middle of a small root, showing a 
few of the tubules infected to a depth of one millimeter (Fig. 6). 
Fig. 3. 
Fig. 4. 
Fig. 3.—Straggling infection of the dentine 
of a root with bacilli, at a point yi mm. below 
the surface. 1000 :i. 
Fig. 4.—Dentine from the root of an abscessed 
tooth, showing the penetration of cocci to a 
depth of about i-iomm. (1-250 inch). The side 
a, b, bordered on the canal. 1000 ;1. 
Nos. 17-19 give results corresponding to those noted above, the 
bacteria having penetrated a very few of the tubules to a distance vary- 
ing from one-twentieth to one-fourth millimeter. 
The conclusion at which I have arrived through the examinations, 
if I may be allowed to draw any conclusion at all after an examination 
of only nineteen cases, is that we need pay no regard whatever to the 
contents of the tubules in the treatment of root-canals. The tubular 
infection is so superficial and so slight that an action upon the peri- 
cementum appears to me to be altogether out of the question. The 
first glance at the preparations under the microscope at once impresses 
one with the utter inadequacy of the infection to perform the action 
attributed to it, Of the cases I examined, the only one in which there 7 
could be at all a possible question of a deleterious action produced 
upon the pericementum by a decomposition of the contents of the 
Fig. 5. 
Fig. 6 
Fig. 5.—Dentine lining the canal of an abscessed root, a, 
b, side bordering on canal; c, modified dentine; d, normal den- 
tine; e, masses of cocci. No penetration of the tubules here 
visible. 
tubules is that represented in Fig. 6. Let us 
see what are the probabilities that such an ac- 
tion really existed. 
In the first place, it may be remarked that 
the root was not abscessed as were many of 
the others, which showed less infection. In 
the second place, we may reasonably suppose 
that the infection of the dentine would have 
been less extensive if the canal had been sub- 
jected to proper antiseptic treatment; as it is, 
about one-tenth of all the tubules contain bac- 
teria more numerous toward the canal, very 
sparingly in the deeper parts of the dentine. 
Three ways suggest themselves by which 
products of decomposition forming in the in- 
fected zone (d) may reach the pericementum ; 
i. The gases accumulating in the tubules 
might be supposed to force the contents of 
the tubuli before them through the narrowing 
tubules, the stratum granulosum, and cement 
directly upon the pericementum. Personally, 
I place such a process entirely out of the 
question for the following reasons ; There is 
no trace whatever of any change to be de- 
Fig. 6.—Sector of a cross- 
section from a diseased root. 
a, cement; b, stratum granu- 
losum ; c, very narrow and 
finely branched tubules; d, 
infected district. 150:1. 
tected in the structure of the dentine which might indicate a devel- 
opment of gas in the tubules. Again, looking at Fig. 6, we find the tubules gradually narrowing and becoming finely branched as we ap- 
proach the cement, and, bearing in mind that the contents of these 
tubules not being infected cannot have undergone any change, we will 
find it impossible to explain how products of decomposition from the 
infected district could force the contents of the tubules through the 
gradually narrowing canals, through the stratum granulosum, and 
through the cement to the pericementum. 
2. Gases may break up the union between the fibrils and the walls 
of the tubules, and so, without dislodging the contents of the tubules, 
make their way gradually along the tubuli, etc., to the pericementum. 
Aside from the fact that the sections reveal no trace of such action, I 
conceive that it would require an enormous pressure to force bubbles 
of gas from the zone d to the surface of the cement. 
3. The most probable and, I think, the only way in which gases 
might possibly be supposed to penetrate from the decomposing fibrils 
to the pericementum is by a process of diffusion. This, naturally, 
would apply only to such gases as are soluble in the fluids of the 
tubules. That an action of this nature does take place will be witnessed 
to by the fact that in drilling into a tooth containing a putrid pulp, as 
we near the pulp-chamber, the borings will sometimes be found to have 
an odor of putrefaction. I have not observed, however, that this odor 
could be detected from the more superficial layers of dentine, though 
Dr. Jenkins writes me that in chalky teeth he has noticed the odor 
soon after boring through the enamel. Now, it is quite possible that 
a similar action, in a diminished degree, may take place through the 
solution and subsequent diffusion of gases generated in the tubules 
themselves, though such an action would always remain insignifi- 
cant when compared with the absorption of gases from the pulp itself; 
and the possibility that the whole substance of the root may in this 
way become permeated with the products of decomposition, and to 
such an extent that they should have an irritating action upon the 
pericementum, is very slight indeed. 
In conformity with the observations which I have made in practice 
and with the results of my theoretical and experimental examination 
of this subject, I am in the habit of utterly disregarding the contents 
of the tubuli. If I am able to thoroughly extirpate the pulp and 
antiseptically cleanse the canal, I have nothing to fear or to anticipate 
through decomposition of the contents of the tubuli. 
To those who may be of a contrary opinion I would suggest that 
the only way for them to fill canals is to close the foramen with cement, 
gutta-percha, or some similar material, and then fill the canal with a 
substance such as pulverized charcoal, which will absorb the gases 
which they believe to be formed in the tubuli.