often breaks just below the surface of the root, which causes a
lot of time to be consumed in order to remove it and fit a new one.
Since we have employed gold posts we have not had any trouble
Before reaming out the canal it is advisable to test the length
of it. This may be done by placing a small piece of rubber
dam on to the upper part of a broach before passing it up the
canal and then closing the rubber down to the face of the root
and drawing the broach away carefully, which then gives us
the length. Lay this down on the bracket table for reference.
We take a piece of thick gold oval wire and taper it down to the
required size and adjust the canal to it according to the general
size and build of the tooth. The post should be longer inside
the canal than the length of the crown, and the part that approx-
imates to the face of the root should be thick, as that is the
weak spot and where the strain comes. The post may be used
as it is, or, better still, the orifice of the canal may be enlarged
with a very large round bur kept for the purpose so as to accom-
modate a ring of size A gold round wire being soldered to the
post. This ensures great strength where it is needed, and makes
a good hold for the cement. The coronal end of the post is then
carefully filed if it is too thick in order to fit into the hole of
the porcelain crown; this must be quite parallel, otherwise the
crown will work loose if it is at all tapered. We then take a
pair of cutting pliers in one hand and the post, held in a pair of
pliers, with the other and cut threads round it for the purpose
of making a hold for the cement. The crown is carefully fitted
to the root in the mouth or, if more convenient, an impression
with plaster and a wax bite may be taken and the crown fitted
in the laboratory. We prefer to fit it in the mouth. Now, if
CROWN AND BRIDGE WORK 327
the edges of the crown overhang the edges of the root it must
be definitely cut to the alignment of the angle of the surface,
and not merely bevelled. If necessary, a large portion of the
porcelain must be cut to secure a natural and artistic
appearance (see Fig. 96). If Ash's or the Dental Manu-
facturing Company's Robbin's crowns are\ employed they
may be cut to any extent to match the configuration of the
neighbouring teeth. They can then be disked up with
medium carborundum discs and finished with very fine cuttle-
fish or sandpaper discs. If a high polish is desired they may
be finished on the lathe with a buff, using pumice and dry
whiting. A cement of good quality must be used to fix it into
the canal. During the whole operation the mouth must be kept
FIG. 96. SPECIMENS OF CROWN WORK. :
A, Porcelain crowns with surfaces ground and polished to make them flush
with the contour of the roots ; B, gold shell crowns, showing shaped
cervical edge ; C, lower bicuspid coned and cusps ground before making
a crown .
quite dry with napkins, wool rolls, and the saliva ejector. The
napkin will have to be swung out of the way occasionally to test
the position of the crown and bite. When the post and crown
are ready the canal is dried out with absolute alcohol and hot air.
The periphery of the face of the root is cleansed with peroxide
of hydrogen, then with alcohol, and well dried. Crown and
bridge cement is then carefully mixed to the proper consistency,
and with a fine plugger point we work a little into the hole of
the porcelain crown, which also has been carefully cleansed and
dried; smear some around the coronal end of the post and plunge
it into the crown; then build more cement around the whole of
the post and lay it down on the slab while we pass a little cement
right up to the apex of the canal. This process is important,
328 OPERATIVE DENTAL SURQERY
as we wish to medicate the end of the canal. We take a very
fine plugger, catch up a little cement on to it, and dab it on
to a small piece of thymol crystal which has been crushed before
we mixed the cement. We only require a trace of this drug.
We then pass this right up to the end and twist it round. The
remainder of the cement is then placed into the root canal so
as to avoid air getting locked in. Then take the tooth and post
and plunge it without any force into the canal and pause about
halfway to release the compression, and then push it home
and hold it for a minute. When the cement is quite set the
excess is trimmed away and the patient is directed to hold a
little warm water in the mouth to complete the setting of the
cement. The cementing of the post into the crown must be
done first, because if the canal is filled first we shall find that
the warmth of the mouth will cause it to set and thus spoil the
whole thing. The apex of the canal may be sealed first if
desired before the post is fitted, or the post may be cemented
to place first, and then the crown fitted afterwards. We prefer
this method because there is a certain amount of undesirable
play when carrying post and crown into the canal together. The
writer has fitted hundreds of porcelain and pivot crowns, and
regards the fixing of them with a gold post of suitable size as an
entirely satisfactory operation, and one which may be carried
out with every confidence of success as any other operation in
dentistry. Years of experience with this method have shown
that it contains the solution of the permanence of root filling
which appears to cause so much controversy. The apex of the
root canal and its foramina being the vital spot, slight medication,
in proportion to the smallness of the risk of sepsis with solidity
of the filling by condensation, secures its permanence. By
this we mean that it is not necessary to have a mass of medi-
cament to take care of a tiny crevice which might contain the
origin of sepsis. We can overwhelm the risk and make a much
greater one because the porous nature of some filling materials
allows the serum from outside the apex to permeate inside the
canal. In this way accommodation is ultimately afforded for
the harbouring of micro-organisms which infect the outside
apical tissues, giving rise to granulomatous areas which can be
detected in radiographs taken in suspicious cases. The root
filling must be solid or impermeable in substance, there must
not be any space or any tenuity as opposed to condensation.
CROWN AND BRIDGE WORK 329
This condition is secured by the method which we have described.
Upper and lower bicuspids are suitable for post crowns. Upper
and lower molars are sometimes suitable for porcelain crowns
by making a Richmond band or collar to the root with JL-shaped
pieces underneath in place of a post, and a post soldered to the
crown side to take a tube tooth or a porcelain crown. In this
case the gold cap is made to the root in the mouth, and a com-
position impression and bite is taken so that the post and crown
may be finished in the laboratory.
For crowning molars and also bicuspids, where they are being
utilized for bridgework as abutments, shell crowns are suitable.
If there is a cavity in a tooth that is to be crowned in this way,
the practice of relying upon cement to fill it when cementing the
crown on is bad. The cavity should be faithfully filled with
amalgam as if there were no crown to be fitted. This is one
of the causes of leaking which finally leads to septic trouble
under a crown or a bridge. Oxyphosphate of zinc is a necessary
dental cement, and is much abused because too much is expected
of it. The acids of the mouth will sometimes dissolve the cement,
which, as it becomes removed, provides space for them to con-
centrate and remove the remainder more quickly. When the
cavity is reached the process goes on which removes the cement
filling until the whole thing becomes septic and hopeless because
the bridge has to come off and the septic tooth extracted. If
the cavity edges had been securely filled with amalgam the
bridge could be cemented on again.
The next procedure after filling the cavity is to cone the
tooth, which means that we must at least make the sides parallel
so that the cervical edge of the gold collar or band fits snugly
round, and yet will pass on and off while making the gold crown
(see Fig. 96). This is carried out with a square carborundum
wheel \ inch thick and f inch in diameter; the smaller parts
and bulbous surfaces are dressed down with smaller stones, or
cup-shaped ones. If the tooth has one or two teeth immediately
touching it we must make a space by trimming its approximal
sides. This process involves great care in order to avoid lacerat-
ing the gum, cheek, or the tongue. There are many kinds of
abrasive discs for this purpose, which meet the difficulties
involved. In some cases the enamel is adamant, which, ccm-
bined with the tightness of the approximating teeth, makes it
a difficult process. The disc will sometimes get suddenly wedged
330 OPERATIVE DENTAL SURGERY
and then jump off suddenly, or it will break, leaving a jagged
edge to run amok. The cutting of the soft tissues must be
avoided, yet the tooth must be cut through. The quicker it is
done the better the cutting will be. A firm, steady wrist is
essential in order to control the engine handpiece, and practice
brings the necessary skill. Students, when first using a bur,
find that it will run about everywhere but where they want it;
so with a cutting disc, if it is not steadily held it is out of control
and does not cut as definitely as it otherwise would. The safest
procedure is first to make a division with a fine steel ribbon-
saw strip held with the fingers and followed if possible with
a separating file. Knife-edged cutting discs and saws must be
used with great caution. Vul-carbo discs and copper discs
used with carborundum powder are as safe and efficient as
anything can be for this purpose. However, with practice out
of the mouth the nature of the process can be investigated. An
experienced operator will do it in the mouth with speed, con-
fidence, and skill. An assistant holding a water syringe and
slowly dropping a little cold water on the disc will help the
cutting. Having coned the tooth we proceed to grind down the
cusps of the natural crown in order to make room for the top
or biting portion of the gold crown. In doing this operation
we find in live teeth with deeply defined cusps, that when we
grind on the centre of them there is a decidedly sensitive spot.
If we take a new, coarse carbo-stone and keep it well moistened
with cold water we can cut them quickly and with a minimum
of pain. A skilful manipulation of the carbo-stone is necessary
to secure this dual purpose, and can be acquired by practice.
The nearest guide to its acquisition is that the wheel should be
applied with a side pulling action and not with a direct vertical
pressure. Considerable power is developed by the sweep of the
rapidly revolving stone with this slide slip movement.
The fitting of the collar is the next stage, which is very im-
portant. It cannot be done accurately enough on a plaster
model, because the gum margin cannot be correctly shaped.
The thickness of 22 carat gold should be No. 4 or 5 No. 4 for
single crowns and No. 5 for abutments on a bridge. The
measurement of the tooth is taken with a dentimeter, which
consists of a loop of binding wire held by a clamp. The loop
is placed around the tooth, and the ends twisted up closely but
not too tightly. It is removed and one side is cut through,
CROWN AND BRIDGE WORK 331
closely against the twisted part, and straightened out, which
gives us the length which is marked on the gold, allowing for
a slight lap. The wire is then roughly cut and bent at a right
angle to find the depth of the collar with relation of the lowest
depth level of the gum to the morsal edge. This is then marked
on the gold for its width. Bend the piece of gold, which has
been cut to the ascertained measurements, so that the join
comes in this case in the centre of the lingual surface, but for
a bridge it is better to make it on the inner side so as to incor-
porate it in the solid part which forms the dummy crowns. Be
careful to see that we form a parallel cylinder and make sure
that the cervical edge fits closely. This is done by holding the
band together with one hand while marking the joint lap with
an instrument in the other. When the collar has been removed
we can then tell where the joint has to be soldered. To remove
the spring in the gold before boraxing it we grasp it with tweezers
and hold it in a Bunsen flame first, to anneal it. Solder it with
22-carat gold solder or a suitable high carat solder and hold it
in the Bunsen flame until it flows well. The band is then replaced
on to the tooth and tapped with a crown punch and mouth
mallet, but not heavily, and where the edge of the band is short
it is marked, removed, and in this way it is finally trimmed,
filed, or disked, until the edge is accurately fitted to the gum.
The patient must not be hurt, as this indicates that we are
injuring the periodontal membrane. If a band is forced at
any point on to the pericementum it will give great pain and
cause periostitis and lead to its absorption, which thus causes
leakage at the cervical edge. It will now be seen that a crown
band cannot be accurately fitted to a plaster model however
accurate it may appear to be. The surfaces, particularly the
buccal side, can be contoured with suitable contouring pliers.
Nothing looks worse than a straight-surfaced crown, which looks
more like an umbrella ferrule than a tooth. On the other hand,
there are many crowns which look well shaped and sleek at the
expense of the amount of gold that should be in them. Thin,
paper-like crowns are not rigid enough to withstand the stress
of mastication, and give way by buckling and becoming loose
and perforated.
Having made the collar we now have to construct the top,
which consists of making a joint with the collar and a biting
surface to articulate with the antagonizing teeth_and sufficiently
332 ' OPERATIVE DENTAL SURGERY
strong and thick to do its work. There are several methods of
making a top to a crown:
1. A quick method.
2. Striking up a top.
3. Casting a top.
4. The diaphragm method.
1. A suitable shaped top is selected on the crown die-plate,
and a piece of No. i or No. 2 thickness of fine gold is struck
into it with a large lead shot or a small piece of lead. It is then
adjusted, if necessary, so that the contour of the top corresponds
to that of the band. A piece of high carat solder is just tacked
on one side and then on the other, but it must be a small piece.
The crown is then put on the tooth and the patient bites well
on to it. It is then taken off and the edges are soldered with
a lower carat solder than was previously used, which prevents
the other joints on the crown shifting in any way. Skilful
work can be done by using various carat solders in crown work.
The cusps of the crown are filled in with solder so that the crown
neither becomes perforated through biting stress or buckled
up. This method is suitable where there is plenty of room for
the bite.
2. In some cases there is very little room available for the
top owing to the extreme sensitiveness of the tooth surface.
We must secure room at every part to take a No. 7 thickness
of gold. We put the collar-band on to the tooth and place a
small piece of soft composition on top and let the patient bite,
then hold the compo up to the light, and if there is a hole, a
little more tooth surface must be ground away. A piece more
compo is then placed on to the tooth, and the patient bites
again on to it. It is cooled with a jet of water and removed,
also the band. The band should be marked so as to replace
it in the compo correctly, and a model and bite made in the
laboratory. A No. 7 thickness of 22-carat gold top is then struck
with a zinc die into a block of lead mixed with a little tin, then
soldered to the band and finished. Before casting a model for a
crown, care must be taken to run a little marble dust and plaster
(3 parts to 4) into the collar, because when the high heat is
developed for soldering it, plaster alone will contract very much,
which allows the solder to run in and encroach, thus causing
the crown to be raised when fitted on the tooth. A crown that
CROWN AND- BRIDGE WORK 333
does not go home properly will cause undue pressure on the
periodontal membrane, making it sore, and inflammatory
trouble commences straight away.
3. A top may be carved suitably in inlay wax and cast, then
soldered and finished. A crown may be nicely contoured by
this method.
4. The strongest form of top which is suitable to stand the
strain of a bridge is made by first securing a fair amount of
room between the bite and the tooth surface. A diaphragm
of fine gold is soldered to the top of the collar and placed on the
tooth and tapped with the crown mallet into its place. In doing
this an impression will sometimes appear of the surface under-
neath on the gold diaphragm. The crown top has now to be
completed. We place a piece of compo and take an impression
in the same way as for No. 2. A suitable top is selected from
the die-plate and placed on the crown, and the bite adjusted.
The top is marked with the collar so that we can tell where it
goes when removed. The cusps are filled with high carat
solder first and then placed on to the crown and held in
position with a crown soldering clamp. It is now soldered
solidly with a lower carat solder, which is drawn right through.
The object of filling the cusps with a high carat solder first is
to prevent their becoming hollow when the final filling in is
executed. The crown is then trimmed up and completed.
We have indicated the main features of crown work but, as
we have already stated, it is capable of endless, variety and
combination of details. It provides a wide field for the ingenuity
of a good mechanic and the subtle finish of an artist. The
utilization of two or more crowns may form the piers or abut-
ments of a bridge. When these have been properly made and
fitted into position, but not cemented, we proceed to take a
bite with wax. An impression is then taken with plaster of
Paris to include the field of the bridge. This may be a partial
impression or a complete one of the jaw. The plaster may
have to be fractured in order to remove it, and the crowns and
broken parts placed very carefully together in the tray and
waxed into position. A model and bite is then made in the
laboratory, and the spaces' between the crowns are filled in
with platinum pin teeth or interchangeable teeth facings, and
finally soldered into one piece with strengthening bars adjusted
previously to prevent contraction taking place from the solder.
334
OPERATIVE DENTAL SURGERY
This part of crown work comes into the domain of mechanical
dentistry and is an extensive subject. Removable bridgework
provides a still greater field for variety, ingenuity, and really
accurate work. It has the advantage of providing the patient
with a comfortable denture which is secure in its place with a
minimum of size so as to allow plenty of room for the tongue.
It also allows of proper cleansing.
INDEX
ABSCESS, 147
dental, 159
Aconite, tincture of, 184
Adrenalin, 175
Alcohol, 175
Alum, 182, 233
Alveolar process, 60
Alveoli, formation of, 34
Amalgam, condensation of, 289
fillings, 283, 285
formulae, 284
Ameloblasts, 22
Ammonia bifluoride, 185
Anaemia, 204
Anaesthesia, Dr. Gwathmey on, 304
pressure, 304
Anastomoses, 81
Aneurism, 204
Anti-thrombin, 103
Antral suppuration, 154
Antrum, description of, 60
empyema of, 60
importance of, 63
Apical foramina, 299
Arachnoid membrane, 114
Aromatic sulphuric acid, 186
Arsenic, 181
action and use of, 303, 304, 306,
37
Arteries, anastomoses of, 74
description of, 74
distribution of, 74
Arterioles, 78
function of, 89
Arterio-sclerosis, 74, 204
Artificial respiration, 222
Asphyxia, 84
causes of, 93
stages of, 94
Bacteria, 150
Bacteriology, 149
Basement membrane 65
Bobreuf's Phenol Sodique, 201, 232
Buckley's phenol comp, 180
Bur lubricant, 266
Blood, absorption of gases, 84
arterial, 71
bactericidal power of, 99
description of, 82
Blood, carbonic acid gas in, 84
coagulation, reason for, 97
coagulation of, 100
affected by certain con-
ditions, 102
composition of, 101
corpuscles, description of, 83
formation of clot, 101
function of, 68
immunity of, 97
mechanism of circulation, 88
oxygen in, 84
percentages of gases in, 91
plasma, 83, 86
platelets, 83
power of, in combating disease,
98
pressure, 88, 95
process of coagulation of, 102
proteins in, 86
resistance of, 147, 158, 170
stream, velocity of, 89
supply of teeth, 49
to teeth, 126
temperature of, 82
venous, 71
Bloodvessels of mouth, 66
Bone, chemical composition of, 50
qualities of, 49
structure and characteristics of,
5i
Bones, cranial, 52
facial, 52
function of, 50
of the skull, 52
Brain, connective tissues of, 115
coverings of, 114
description of, 108
divisions of, in
functions of, 108
neuroglia of, 115
ventricles of, 112
Bright's disease, 204
Calcium salts, in coagulation of the
blood, 104
sulphide, 179
Camphenol, 184, 201, 232
Capillaries, 78
Carbolic acid, 179
535
336
OPERATIVE DENTAL SURGERY
Carbolizcd resin, 180
Caries, Dr. Register on, 264
Cartilages, capsular, 136
external lateral, 136
interarticular fibro-, 136
internal lateral, 136
stylo-mandibular, 136
Cavernous sinus, 150
Cavities, classification of, 263
defining limits of, 267
discovery of, 262
lining of, 273, 285
plugging of, 273
preparation of, 264
Cavity dressings, 270, 271
preparation, pain in, 279
methods of securing dry-
ness, 280, 281
vulnerable parts, 285
Cell, the, 71
action of drugs on, 172
description of, 15
Cells, origin and development of,
70
Cementoblasts, 48
Cementum, 28
description of, 45
Central nervous system, 106
Cerebellum, 112
Cerebral cortex, 115
Cerebrum, in
Children's teeth, fillings in, 239
regulation of, 249
Chinosol, 183
Chloretone, 178, 193
Chloride of calcium, 1 79
Cinnamon oil, 177
and tannin, 269
Circulation, portal, 80
pulmonary 71
systemic, 80
Cocaine, 191
poisoning, symptoms of, 200
Comparative anatomy, advantages
of, 49
Copper sulphate, 185
Corium, 65
Corpora quadrigemina, 112
Corpus callosum, in
Cortex, convolutions of, 116
Creosote, 188
Cresylic acid, 184
Crown and bridge work, causes of
failure, 323
plaster of Paris impres-
sions, 333
Crown work, 323
cutting divisions between
teeth, 330
registering length of root canal,
326
Crowns, gold shell, 329
porcelain, 326
cementing of, 327
shell, fitting of collars, and
soldering tops, 331
Crura cerebri, 112, 119
Deglutition, 138
Dental abscess, drainage of, 318
treatment of, 300
arch, contraction of, 250
caries, origin of, 264
follicle, 20
follicles, 30
periosteum, 28
pulp, 28
description of, 44
origin of, 27
Dentalone, 178
Dentinal papillae, 20
Dentine, calcification of, 22
carious, stages of, 269
chemical composition, 44
cutting of, 267
decalcified, tanning of, 269
description of, 40
Dentition, 249
abnormal symptoms of, 37
normal symptoms of, 37
vagaries of, 38
Development of size of jaws to
accommodate the teeth, 248
Digitalis, 93
Dislocation of lower jaw, 56,
137
treatment of, 160, 161
Drugs, classification of, 173
used in dentistry, 174
Dura mater, 114
Effect of respiration on circulation,
89
Electric cautery, use of, 280
Eminentia articularis, 53
Empyema, 147
Enamel, calcification of, 22, 27
chemical composition of, 40
cutters, Dr. Black's, 265
cutting, 265
description of, 38
organs, 19, 20
rods, 265, 266
Endocarditis, 203
Enzymes, 149
importance of, 103
Epiderm, 16
Epithelium, 65
band, 18
Epithelial cells, 17
cords, 19, 23
INDEX
337
Epithelial cords of deciduous teeth,
separation of, 24
of successional teeth, sepa-
ration cf, 25
tissue, 16
Epulis, 165
Erythrocytes, 83
Erythrophleine sulphate, 181
Essential oils, 177
Etiology, 144
Eugenol, 178
Exostosis of roots. 28, 166
Extraction of teeth, difficult cases,
228
movements for, 226
preparatory treatment, 231
principles of, 223
Fainting, 73
Fibrin, 101, 104
Fibrinogen, 86, 104
Fibroblasts, 48
Fillings, condensation of, 274
irritation caused by, 273, 278
Fistula, 159
Foramen magnum, 119
ovale, 55
rotundum, 55
Foramina, Scarpa's, 64
Stensen's, 64
Forceps for extraction, 224
Formaldehyde, 182
Frontal process, 60
Gasserian ganglion 55, 120