The construction of this formula is based upon the chemical
compatibility of the various ingredients. It is non-irritant, has
suitable working qualities, and sets hard. Its degree of medica-
tion is sufficient.

The canals are cleaned out with absolute alcohol applied with
a square, soft canal broach, which has a wisp of Japanese
bibulous paper caught at one end and twisted around it. We
hold the piece of paper between the thumb and forefinger of one
hand and the square broach with the other, thumb and finger,
and lay the point of the broach upon the paper, then pinch
the paper and twist the broach, when it becomes securely fastened
on to it . For employing medicaments we apply them in the same
way, but not quite so tightly wrapped. This enables us to
carry the medicine to the apex where it is required without
squeezing it out in its passage up the canal. By turning the
broach in the reverse direction we loosen it and bring it away



316 OPERATIVE DENTAL SURGERY

while leaving the dressing behind. Care is required in applying
dressings on cotton-wool, as they are apt to become jammed in
the canal and are difficult to remove.

2. The second part of root treatment consists of what might
be called advanced root treatment. The tooth in this case is
dead when we are called upon to examine it, or it may be accom-
panied by a large swelling of the tissues round the apical area,
or there may be a fistulous opening on the gum either lingually
or labially with pus oozing from it. Dead teeth which give no
indication of abscess trouble must be treated as though they
were septic, and if there is no septic complication the sooner
will the tooth be ready for filling. Unfortunately, many
apparently harmless dead teeth prove to require serious treat-
ment, so that we must not be misled by apparent absence of
inflammatory symptoms. Even if a dead tooth is apparently
harmless, yet the canal of the root being full of debris must
be submitted to the same precautions and care as if it were
septically active. The treatment of dead teeth with abscess con-
ditions is rightly regarded as a difficult operation, but as it involves
skill of a high order and ensures a patient's gratitude when
successfully accomplished, renders it a sufficient inducement for
the operator to become competent in its practice.

It must be understood that only an apical abscess can be
dealt with. This condition can usually be diagnosed by seeing
the external tissues highly inflamed, or a swelling at the apical
region accompanied by extreme tenderness on pressure being
applied, or the tooth feels very tender to bite on, caused through
the periodontal membrane being highly inflamed. Any of these
symptoms may be accompanied by the existence of an abscess
sac which for the time being may, or may not, be discovered.

The object of the first part of root treatment was the whole
of the pulpal area inside the tooth, but in advanced root treat-
ment our object is to deal with diseased conditions outside the
tooth involving the immediate apical region of the tissues. In
order to carry it out successfully we must insist on the faithful
observance of five principles :

1. Our object must be to reach the apex of the canal and just

through it.

2. We must sterilize the column of putrescent debris con-

tained in the canal to prevent infection of the periodontal
membrane from it.



ROOT TREATMENT AND FILLING 317

3. We must secure drainage by instrumentation.

4. We must apply suitable medication or drug treatment to

heal the abscess and render the whole area aseptic.

5. Root filling well condensed.

All these principles must be carried out in each case if success
is to be attained.

1. If we cannot carry out the first principle we may as well
abandon our endeavours altogether. There are some roots
which render it impossible to reach the apex, such as the buccal
roots of upper molars and the anterior root of a lower molar,
upper laterals, and lower incisors. Upper centrals, canines, and
bicuspids, lower canines and bicuspids, usually have good canals
which enable us to carry this principle into effect.

2. If a root has not infected the dental periosteum we must
be careful to see that we do not disturb its putrescent contents
until it has been sterilized by suitable medicaments. Or if an
abscess is present we must not force more septic debris into it.
The use of pure formaldehyde solution or formalin, with tri-
cresol, equal parts, as recommended by Dr. Buckley, or formalin
and creosote, equal parts, which may be introduced on cotton-
wool in a carefully prepared enlargement of the orifice of the
canal and sealed in with cement to retain the formaldehyde
gas which is developed by the warmth of the mouth, will sterilize
the column of debris and neutralize the irritating gases, am-
monia, and sulphide of hydrogen, which are the products of
putrescence. Experience has shown that these strong per-
centages of formalin should not be applied near the apical tissues,
but they are useful for this purpose only.

3. The principle of securing drainage is most important.
We regard efficient instrumentation and medication as being
the foundation upon which advanced root treatment rests.
Disregard or modification of its requirements spells failure
straight away. The more general use of radiography will
undoubtedly be a valuable adjunct to treatment, as by a correct
reading of radiographs granulomatous areas and abscess sacs
may be discovered. The size and direction of roots by its aid
can be revealed, which will make instrumentation easier. To
secure a passage for the drainage of an abscess there must
therefore be a carefully carried out process. We must enlarge
the canals sufficiently to allow paper points to pass up and
syphon out any pus that may be present, and subsequently to



318 OPERATIVE DENTAL SURGERY

pass up a suitable medicament for healing the inflamed tissues.
The opening of the foramen at the apical end of the root must
not be large, but only sufficient to allow the passage of the fine
paper points. We open out the mouths of the canals with
root burs, then follow on with Gates-Gliddon drills of suitable
sizes and complete the apical portion with Beutelrock's, Kerr's,
or other similarly shaped nerve canal drills, care being taken
not to drill through the sides of the canals or to penetrate the
apex farther than the external surface. The paper points may
pass up as high as the space of the abscess will allow. Root drill
lubricant is used for all cutting burs and drills in order to facili-
tate cutting and to avoid blocking up with hot debris which
becomes hard, and to prevent fine drills from breaking. Drills
should be withdrawn now and again to allow of clearance of
the debris. An experienced root filler can tell intuitively when
he has pierced the apical end. Practice out of the mouth is
time well spent. If there is an abscess sac, a broach will some-
times go some distance beyond the apex, but if there is no sac
but inflammation of the dental periosteum, the instruments
must not inflict any damage on it. An active abscess sac will
probably require one dozen to eighteen paper points to empty
it at the first application, after thoroughly sterilizing the canal
by previous dressing as explained under principle 2 . A dressing
containing a suitable drug is then sealed in and left for a day
or more, according to the severity of the case. Drainage is
again carried out, and a dressing applied until the discharge has
ceased and all tenderness on external pressure has disappeared.
The operator should note how many paper points were used
on each occasion. When treatment is completed there will
always be a slight moisture on the extreme end of the paper
point.

We sometimes find that an apical abscess will give us a lot
of trouble, and it is as well for us to realize the nature of the
forms which the sacs take in their development. A brief out-
line of the stages of disease, and their final consequences
to a tooth, may be stated as follows: The mouth may be
compared to a pond teeming with organisms which thrive on
its bed and banks. The oral cavity provides suitable accom-
modation for bacteria consisting of pathogenic or disease-pro-
ducing types, and non-pathogenic types, which are harmless
under ordinary conditions. If a suitable portion of the mouth



ROOT TREATMENT AND FILLING 319

around the teeth, such as the interdental spaces or a ledge
or crevice on the tooth-surfaces, becomes prepared through
lack of cleanliness, certain micro-organisms form a colony and
enclose themselves with a formation of gelatinous plaques under
which lactic acid is produced sufficiently concentrated to attack
and dissolve the lime salts of the enamel. They then work
upon the dentine until the calcium salts have been removed and
the soft, decalcified tissue is exposed. Some micro-organisms
have the power of peptonizing or dissolving this until it is broken
down into debris. When the pulp has been disorganized it
presents a menace to the periodontal membrane, which at some
time or other becomes inoculated with septic matter from the
putrescence of the canal. An abscess sac is formed which at
first may be very tiny, but may develop into a large one
with considerable swelling extending into the surrounding bone
and external soft tissues. As the internal pressure develops
it seeks a way out in order to empty itself. A fistulous tract
or canal is formed which usually takes the line of least resistance.
It finally ends with an outlet which is commonly on the external
apical surface of the gum against the tooth which is the original
cause of it; but it does not always do this, and that is where
trouble is likely to become serious to the patient. The fistulous
canal and opening may take another direction. It may travel
along the external surface of the tissues and break some way
off from the original tooth; or along the palate, breaking in the
centre of the vault ; or farther along into the soft palate, emptying
into the throat, where the pus will weep out and get into the
larynx, thereby infecting the lungs and setting up septic pneu-
monia ; or it may break into the floor of the antrum and set up
an empyema; or travel up the facial tissues or into the nasal
cavity; or, again, along the neighbourhood of the inferior dental
canal and break into the throat. The operator must be prepared
to act as his judgment and experience guide him. If the
fistulous opening is on the gum, somewhere near the tooth
being treated, it is the easiest form of abscess sac to deal with,
as we know the extent of it, and can pump medicaments through
with a fair chance of stopping the discharge.

4. Suitable medication is an important factor in itself. It
is remarkable how some operators expect a cure-all drug appli-
cable to every case. We may all have a routine agent or two
for straightforward cases, but if our intention is to face diffi-



320 OPERATIVE DENTAL SURGERY

culties and overcome them, we need a selection of drugs as our
root- treatment armamentarium.

The dental profession is indebted to such men as Buckley,
Callahan, Tomes, Miller, Black, Prinz, and Crane, for their
investigations into the nature and action of drugs suitable for
root treatment and filling. Their combined laborious work
cannot have been in any way simple, but their labours have
certainly simplified many obscure problems and made the
subject capable of being better understood.

The utilization of formaldehyde vapour for disinfection of
the canal and dentinal tubuli, and for neutralizing the irritant
gases from putrescence, as demonstrated by Dr. Buckley, is
an important bactericidal remedy, but it must be applied with
prudence. A 50 per cent, formalin mixture with tricresol
or creosote is good for the initial dressing at the mouth of the
canal, but this agent is too irritating for application near the
apex. It has a marked preservative and mummifying action
upon dead tissue, but this is not desirable where vitality is
required. A 3 per cent, solution is quite strong enough, and
should not be forced through the apex; this strength can be
added to mummifying paste and incorporated well into the
powder. A non-irritating dressing for putrescent conditions is
Black's 1-2-3, which is a mixture of carbolic crystals, i part,
oil of cassia, 2 parts, and oil of wintergreen, 3 parts. Oil of
cinnamon is a powerful and penetrating bactericide, but must
be kept under control, if used pure, because if it should get out
at the apex it is too irritating, and will quickly produce the
symptoms of inflammation which we are endeavouring to
prevent. It may be mixed with glycerine in varying propor-
tions, or used as a dressing mixed with zinc oxide, which will
prevent any free oil escaping; or it may be applied on a wisp
of non-absorbent cotton-wool and partially dried before inser-
tion. Cinnamon oil is valuable because it contains cinnamic
aldehyde. Oil of geranium must be controlled in a similar way.
Thymol is regarded as quite a dental medicament, and is a
valuable one owing to its bactericidal qualities and low degree
of toxicity. It is very irritating when applied in a concentrated
form in a mixture, but is capable of exercising its potency in
weak solutions. It may be added to glycerine, i in 200 parts.
One grain of alum, which has a mild astringent effect, may be
added.



ROOT TREATMENT AND FILLING 321

Sometimes we have a case where there is no sign of pus, but
the periodontal membrane at the apex of the root is exceedingly
painful, and the drugs which we apply to ordinary cases make
matters worse. In these cases palliative dressings are, of course,
needed. Paramonochlorphenol, methyl - salicylate with 5 per
cent, carbolic acid crystals, and creosote in weak solution with
glycerine, will usually give relief.

With cases where there is a fistulous tract and opening and
the pus is difficult to stop we can pump a medicament right
through it. This is carried out by using the root canal as a
syringe barrel and a canal plugger or a broach as the plunger.
The broach is warmed and white wax is run round slightly and
bibulous paper wrapped round. It is then dipped into one of
the following mixtures and worked into the canal patiently with
a pumping movement until we see the solution appearing at
the opening. At a subsequent sitting we may wish to repeat
the operation, but find that the opening has closed; we can,
however, reopen it with a sterile ball probe and proceed as
before. The suitable mixtures are: Camphenol, 2 per cent, in
glycerine; creosote .in glycerine, I part to 7 or stronger; and for
stubborn cases, .phenol-sulphonic acid (see paragraph on p. 187).

The application of a counter-irritant to the external surface
of the gum is sometimes useful, such as tincture of aconite and
liniment of iodine mixed together, or the use of dental plasters.

Internal remedies will often help matters, such as an anti-
bilious pill to regulate the liver it need not purge and can be
repeated the following night; aspirin, dose 5 to 15 grains; or
the patient's medical man can administer a course of tonic or
other treatment in order to assist the resistance of the blood.

The recuperative powers of the patient is a factor which
must not be overlooked, and root treatment should be withheld
in many conditions of a patient's health, because, after all is said
and done, our endeavours are only means to help the tissues to
recover and to retain their health and vitality.

In some very obstinate cases the continued flow of pus has
shown no permanent sign of stopping. These cases have been
marked by a mixture of blood and pus. After three or four
months' treatment we have had to give them up and extract the
teeth, when we have found in the majority of cases that the
ends of the roots were roughened and partially absorbed. This
necrosed condition is probably caused by the acid reaction of




322 OPERATIVE DENTAL SURGERY

a long-standing septic condition. In other similar cases where
the patient has expressed a wish to still retain the tooth, as no
pain was present, we have plugged the canal with a temporary
root filling of mummifying paste applied on bibulous paper and
left in with the understanding that if it gave any pain or trouble
at all the tooth could then be extracted. To our surprise, in
some of the cases, we have opened the canals six months or a
year afterwards and found that the obstinate discharge of pus
had stopped entirely. These cases have demonstrated that
rest between final dressings is a useful factor.

5. The canals may be filled with our formulae I. or II.; or
with Eucapercha, which is a mixture of :

Gutta-percha base-plate . . "I

-r, I., /-Equal parts.

Eucalyptol . . J

Thymol, i part in 200 parts of the above mixture.

Oxy-chloride of zinc is favoured by some operators.

There is no royal road to root treatment save by practice,
observation, and experience, which may be stimulated by our
personal interest, and our patient's appreciation.



CHAPTER XXI
CROWN AND BRIDGE WORK

THE operations which are carried out in the dental surgery
include crown work. The assemblage of a combination of two
or more crowns as piers or abutments is called " bridgework."
This combination of crowns and abutments is capable of an
endless variety. The form of substituting artificial crowns in
place of broken-down or missing natural ones is most enticing
to patients who have a reluctance or prejudice to wearing a
plate or denture; consequently, they are most willing to have
this kind of work fitted into their mouths. We refer to fixed
bridgework, which is cemented into the patient's mouth and
cannot be removed for cleansing purposes, but is cleaned in
the same way as their natural teeth. One can quite under-
stand a patient's preference for a bridge which keeps the palate
and tongue free from encumbrance. It appeals to them as
being highly skilled and artistic work. But in this case we often
find that the old proverb " that chickens will come home to
roost " is applicable. Crowns and bridgework have been put
into mouths which are not suitable for their reception and
permanent wear, with the result that many medical men are
now condemning them as being traps for septic matter and do
not hesitate to order their removal. So strong is their con-
viction on this point that they will order their removal on the
slightest suspicion of periodontal trouble. Unfortunately, the
charge of abuse against this form of work is not ill-founded,
and the grounds of condemnation may be thus summarized:
badly fitting crowns and abutments cause leakage, which
allows lactic and other acids to concentrate on the dentine at
the necks of the teeth and destroy them; food collecting
against dummy crowns causing hyperaemia of the gums, which
then become foul and septic; badly fixed bridgework through
imperfectly mixed cement, and set without securing a proper
degree of dryness; utilizing dead teeth for abutments, especially

323



324 OPERATIVE DENTAL SURGERY

where the fixed position of a number of dummy crowns causes
too much strain on the periodontal membrane of the socket, the
vitality of which has already been lowered. Hyperaemic and
septic conditions of the mouth always become exaggerated
where bridgework is fixed. The same objections apply to single
crowns, especially if there are several of them in the mouth,
but they are not so serious from an inflammatory standpoint
providing that they are well executed in every detail. Shell
crowns, however, must be included with the same objections
as fixed bridgework. The main point to be considered when
estimating the value of this kind of work is the standard of quality
of the operator's work. From an operative and pathological
point of view even the best of well-fitted collars and joints
transgress the laws concerning the accuracy of flush surfaces
around the cervical area of a filling.

With the reservations and objections to which we have
referred there are many cases where crowns and bridgework
may be fitted and do good service to the patient, but attenticn
to details is imperative. It is impossible to describe this subject
in one chapter. The writer has had thirty years' strenuous
experience with this class of work, and can speak with practical
knowledge of its primary principles:

1. The preparation of teeth with living pulps.

2. The preparation of teeth with dead and septic roots.

3. The fitting of an all porcelain or a porcelain-faced crown.

4. Shell crowns.

5. The stages of making fixed bridgework.

6. The advantages of removable bridgework.

The first two principles have been described under Root
Treatment and Filling, but there are technical points adjustable
to crown work, but no alteration of pathological principles.

Porcelain is universally admitted to be the most desirable
material for the restoration of the missing portion of a tooth.
Porcelain inlays involve an unreasonable amount of time in a
busy practice, but the fitting of a porcelain crown is as near
perfection in our art as can be expected. It involves a lot of
attention to details, but when completed well repays the operator
for his pains.

We will now consider the fitting of a central or a canine
crown. The patient presents the tooth, which either has to



CROWN AND BRIDGE WORK 325

be devitalized or root treatment has to be carried out. The
opening up of the root is carried out with the crown of the
tooth still standing until root treatment has been completed.
This is to allow the gum still to stand free of the edge of the
root, otherwise if the crown were cut off first, the gum would
creep over and trespass on the face of the root, also the patient
would prefer to have the crown standing rather than have a
big space for some time. The crown, then, has to be cut off;
some operators do this by cutting a nick on each side of it and
using excising forceps to cut it off. This is a clumsy method,
because it jars the periosteum to start with, and the face of the
root is splintered, making a rough-edged joint. The better way
is to take a small sized cross-cut fissure bur well dipped into
bur lubricant and apply it to one side of the crown just under
the enamel if possible, then with a sawing motion we cut it
through like a lumberman cuts down a tree- trunk. The bur
may have to be lubricated two or three times, as it gets
clogged up and cannot cut, but engenders heat, which may
break the shank of the bur. There are extra long fissure burs
on the market which are suitable for this purpose, but they
must be thin ones or the cutting will be a clumsy process for
the patient. The extra length is useful as it allows of accom-
modation for a thick crown. We must be careful to hold the
crown with the fingers when it is about ready to fall off. The
face of the cut root must now be ground down so that its labial
and lingual edges are just under the free edges of the gum,
and yet these edges must not be merely bevelled, as it is
impracticable to fit the porcelain crown down over them. The
surface must be perfectly flat from one edge to the other.
A square edged carborundum wheel is most suitable for this
purpose, about inch thick and inch in diameter. A very small
wheel of the same thickness may be used for finishing down the
edges near the gum. If a dressing is put into the root to be
left for a day or two a cap which is shaped like a small drawing-
pin may be warmed, with gutta-percha on to seal it in and to
keep the edges of the gum away. If persistent weeping of
blood occurs after cutting the crown off it may be stopped by
applying a weak solution of trichloracetic acid, or, better still,
by applying the electric cautery. The next stage is the enlarge-
ment of the root canal to accommodate the metal post which
carries the crown. Porcelain crowns with the posts baked .in



326 OPERATIVE DENTAL SURGERY

are very convenient in some cases; but in many others it is
better to fit the post first and try the crown on to see in which
direction it should accommodate the bite. We take a flame-
shaped bur to open the orifice of the canal, but not to bevel it.
Then follow on with a Gates-Gliddon drill, as shown in the
chapter on Root Treatment. A root reamer is then used accord-
ing to the size of the post which we decide to employ. The
post should fit snugly but not accurately, so as to allow for a
film of cement to hold it. The posts supplied by the manu-
facturers are made either of German silver, or nickel alloy, and
gold. We prefer to make the post of 16 carat gold to the size
required for each case. We have found that a nickel alloy post