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ELEMENTARY
AND DENTAL
RADIOGRAPHY
BY
HOWARD RILEY RAPER, D.D.S.
Professor or Roentgenology, Operative Teclinic, Materia
Meaica and Xnerapeutics at tte Indiana Dental College,
Inaianapous. Past Dental Surgeon to tke Indiana Sctool
for tLe Feeble-Minded Youtk. Member American
Institute or Dental Teacners, local, state and national
dental societies. First District Dental Society of
tne State of New York, ^iVestern Roentgen
Ray Society, Associate Fellow A. M. A.,
Section of Stomatology.
WITH OVER 500 ILLUSTRATIONS
SECOND EDITION
Adopted as a Test-Book by the National Association of Dental Faculties
NEW YORK;
Consolidated Dental Mfg. Co.
LONDON :
Claudius Ash, Sons &' Co., Ltd.
^7' ^"Z-l t^
Copyright, 1913
By HOWARD R. RAPER
First Reprint
May 17, 1916
Second Reprint
July 5, 1916
Copyright, 1918
By HOWARD R. RAPER
Copyright, 1913, in the United Kingdom
By CLAUDIUS ASH, SONS & CO., LTD., LONDON
One of "his boys, the -writer,
grasps this opportunity to sno-v^
nis love ana respect for
GEORGE EDWIN HUNT,
M.D., D.D.S.
ty aedicating tnis book to bim.
PREFACE
FIRST EDITION
The object of this book is to teach, first, the elementary
principles of radiography ; second, special dental radiography.
The first part of the book is written on the presumption that
the reader knows nothing about electricity, photography, or
the X-fays, and might therefore be used by anyone zvho wishes
to take up radiographic work, whether a dentist or a physician.
In dealing with the preliminary subjects mentioned, an earnest
effort has been made to avoid useless, impractical and confus-
ing elaboration.
The second part of the book is devoted to dental radiog-
raphy, and is consequently of interest mainly to dentists and
specialists in radiography who do work referred to them by
dentists. It gives in detail the special technic involved in the
practice of dental radiography, also a chapter with one hun-
dred and eighty-three halftone illustrations, demonstrating
sixty-four different uses to which the radiography may be put
in the practice of dentistry.
The use of the radiograph in the practice of modern dentistry
is not a mere fad; it is a necessity, if one wishes to render the
best dental service. Nothing but great good can come from its
more frequent use. To the end of bringing about a more
extensive use of the radiograph by dentists this work is pub-
lished. At present it is the only work of its kind on the book
market.
So many people have helped me in the compilation of
this volume that I refrain from, naming and thanking any
particular individual. A publication of this kind, of necessity,
represents the work of many.
H. R. R.
PREFACE
SECOND EDITION
{The beginner in radiographic work should read this.)
As stated in the preface of the first edition " the object of this book is to teach,
first, the elementary principles of radiography; second, special dental radiography."
When the beginner sees this book, for the first time, and notes its size I can
readily understand the feeling of discouragement which would induce him, to offer
a prayer for a smaller book — one which treats the subject in a less exhaustive
manner, more in the manner in which the average man wishes to take it up. The
prospect of having to " wade through " thousands upon thousands of words to gain
a comparatively few practical facts is certainly not an inviting one. So allow me to
direct the alarmed beginner's attention to these facts: The Place to begin study
is at the beginning of the book — not the middle. The entire subject of Electricity
is covered in only 13 pages! The subject of Elementary Radiography, including the
12 pages devoted to Electricity, and chapters on X-ray Machines, X-ray tubes and
the X-rays, and the technic of Making Radiographs is covered in 84 pages. Only
52 pages cover a detailed consideration of dental radiographic technic. Thus the
entire subject of Elementary and Dental Radiography, as most men will wish to
take it up, is covered in only 145 consecutive pages. From page 145 on, com-
mencing with the chapter on " The Uses of the Radiograph in Dentistry " the book
becomes a reference book, special attention having been given to the index in the
back of the book so the reader may locate the subject he wishes to " look up " with
ease.
Much of the first edition of this book, particularly the elementary part of it,
was written from old notes which I had made for my own benefit at the time I was
engaged in educating myself in radiography. It is owing to this fact more than any
other one thing, I believe, that the book has proved of such definite value to be-
ginners in this work; the tone of the text is not beyond the comprehension of the
man or woman who is just taking up the work. It is with this in mind that I have
refrained from altering the original text as far as possible, in this the second edi-
tion, and have written an appendix to each chapter where necessary, giving therein
such further consideration of the subject as changes, which have developed in the
past few years, seem to demand. In this way I hope to avoid the mistake, most com-
mon with writers on electro-dental and medical subjects, of overloading the reader's
mind with details at the outset.
Though I have followed the plan of revision just outlined as far as possible,
I have nevertheless found it imperative to make a number of changes through the
look and to rewrite Chapters V and IX. These changes I hope, and believe, will
add to simplicity rather than detract from it, and the appendix may be read by those
who have prepared themselves for it and feel the need of further knowledge on the
subject,
I made the statement in the preface for the first edition that " the use of the
radiograph in the practice of modern 'dentistry is not a mere fad; it is a necessity,
if one wishes to render the best dental service." Let me concede that, as some men
use it to-day, the use of the radiograph in dentistry is only a fad.
New methods and things introduced into medicine and dentistry are often re-
ceived -with over and irrational enthusiasm, followed with their equally irrational
abandonment. The extensive use of the radiograph is new. It is just about to pass
through the stage of reaction from over-enthusiasm. Its use will never be aban-
doned, however; so let those of us who know its limitations teach those who do not
know, lest in their discouragement and misunderstanding they fail, for a while, to
avail themselves of this necessity to service. Accordingly the Appendix to Chapter
VI has been written, which, to the very superficial thinker, will seem a tirade against
the use of the dental radiograph, but which in reality is a most pertinent recogmtion
of the fact that we will always use dental radiographs.
The use of dental radiographs, coupled with the modern theories of metastatic
infection as a cause of so many different diseases, brings the old, old problem of
pulp canal work before the dental profession in a new light — the light of the X-
rays and holds it there demanding a solution. It is fitting that we should consider,
at some length, " The Problem of Pulp Canal Surgery" in this volume and accord-
ingly a chapter on this subject will be found in the appendix. The X-rays have'
played a most important part in bringing this problem before us again and they will
play an equally important part in its solution. I direct particular attention to the
chapter on " The Problem of Pulp Canal Surgery and Oral Infection," believing it
contains material of considerable i)nportance to the dental profession, the medical
profession and last, but far from least, the public.
By way of explanation in fairness to some of the men whose names appear
beneath the radiographs in Chapter VII, and in fairness to myself as well, I wish
it known that the radiographs illustrating this chapter were chosen primarily for
their clinical value, and not because they are examples of excellency in radiodontic
work. There are 183 radiographic illustrations; m,ost of these are excellent, many
are ordinary, and a few are poor, but of such definite clinical value that it would be
a sacrifice not to use them.
The policy of not retouching radiographs has been adhered to very closely,
for retouching takes the "life" and "personality" out of radiographs. Only a
very few radiographs have been retouched.
In this edition of the book, as in the first, I have not used the Roentgen words
because I do not like them. Take, for example, the word radiodontia: The equiva-
lent for radiodontia, using the Roentgen nomenclature would be Roentgenodontia.
The literal meaning of Roentgenodontia, as my good friend. Dr. Ottolengui, points
out, would be "Professor Roentgen's teeth."
In compiling material for this second edition I have been impressed again with
the fact that a volume of this kind represents as much the work of his friends as
the work of the author. I will, however, express my appreciation of the co-
operation of my publishers, whose liberal policy of allowing me to use illustrations
as freely as desired, regardless of expense, has added greatly to the teaching value
of the book. Also, I must; I cannot keep from thanking Dr. lohn Callahan and
Dr. Dave House, and my secretary. Miss Fannie Agnew. to whom I am greatly
indebted.
TO TEACHERS OF DENTAL RADIOGRAPHY
For years I lectured to dental students in an effort to teach Radiography. I
failed to get the results I knezv I should get.
I then wrote my book on the subject, assigned lessons in it and quizzed over
the assignments. And, again, I failed to teach the subject as it should be taught.
Students simply floundered about in the assignments and were not able to answer
questions.
J wrote a compend on the subject, and discarded it, because, like all compends,
it failed to cover the subject as well as it should be covered.
I theft read my book {it is proof conclusive that a writer is desperate when
he reads his own hook) and, as I read, prepared a list of questions covering the
most important points in the text, and had this list of questions published in the
form of a small "Assignment Booklet." With this booklet and the text book in the
hands of the student I can now assign lessons by giving a certain number of ques-
tions. After each question in the booklet is the number of the page on which the
answer may be found. The questions are such as to cause the student to read all of
the text included in the assignment. Much longer assignments can be made in this
way. The student has something to " hold to " as he tackles his assignment. He
reads the text with a feeling of security as to what is most important and to be re-
membered, instead of trying to remember everything in, say, a thirty-page assignment
and failing to remember anything, or becoming discouraged and " chucking the
whole assignment."
The results of this manner of teaching the subject have been gratifying beyond
my rather enthusiastic hopes for it. It does not prepare students to go forth and
straightway operate any X-ray machine with immediate and full success any more
than a course of study of motors zvould enable a man to jump into an automobile
and drive it. But it gives students such, a fundamental knowledge of the subject
that they may take up the work with a feeling of confidence in themselves.
This little Assignment Booklet will be found of value also to the man who is
educating himself.
H. R. R.
December, 1917.
■■#
CONTENTS
CHAPTER PAGE
elementary Kadiograpby
L Electricity i
II. X-Ray Machines .14
III. X-Ray Tubes and the X-Rays 41
IV. Making Radiographs 65
Dental Radiograpby
V. Making Dental Radiographs 85
VI. Reading Radiographs 136
VII. The Uses of the Radiograph in Dentistry 146
VIII. The Dangers of the X-Rays . . 273
IX. Purchasing a Radiographic Outfit 292
X. Stereoscopic Radiography 297
JHppenaix
Electricity . . . 319
X-Ray Machines 320
X-Ray Tubes and the X-Rays . 331
Making Dental Radiographs . . . . . . . . 341
Reading Radiographs 357
Uses of Radiographs in Dentistry 416
The Danger of the X-Rays 423
Stereoscopic Radiography 431
The Problem of Pulp Canal Surgery and Oral Infection . 437
Elementary and Dental Raaiograpby.
CHAPTER I.
electricity.
Dental radiography is the science and art of making pictures of the
teeth and contiguous parts with the X-rays. Its place and value in the
practice of modern dentistry will be dealt with later.
Before we can produce X-rays we must have at our disposal that
something called electricity.
Electricity is a form of energy closely related
Electricity. to motion, light and heat. We know it is closely
related to motion, light and heat because these forms
of energy can be made to produce electricity, and electricity conversely
can be made to produce them. Electricity is discernible to but one of the
special senses, namely, feeling. It cannot be seen, heard, smelled or
tasted. Victims of severe shocks have noted a peculiar taste, which they
call the taste of the electricity, but it is my opinion, neither proved nor
disproved as yet, that this taste is due to the presence of new chemical
bodies formed in the saliva by electrolysis. In other words, the passage
of the current of electricity through the saliva causes chemical changes
to occur, resulting in the formation of new chemical bodies, and it is
these new bodies, not the electricity, that produce a taste.
When electricity passes from one place to an-
€ondUCtor$. other the substance through which it passes is
said to be a conductor. A substance throueh which
electricity passes with great difficulty, when at all. is said to be a non-
conductor. Metals are the best conductors of electricity. Silver is the
best, then copper. Copper wire is the most used of any conductor of
electricity. German silver carries electricity very reluctantly, and bis-
muth is the poorest conductor of the metals. It was formerly thought
that electricity traveled on the surface of a conductor, but if this were
true a round wire could be made to carry more current by simplv flat-
tening it and so making the surface greater; while, as a matter of fact,
2 ELEMENTARY RADIOGRAPHY
the flattened wire would carry less, because of the condensation of the
metal incident to flattening. The human body is a conductor. Wood,
glass and vulcanite are examples of non-conductors.
When electricity passes from one place to another through a con-
ductor, what is known as the electric current is established.
There are four kinds of electric currents: (i)
0urr
r
,4 A
7m
C P
Fig. 25.
Fig. 26.
Fig. 25. A, movable arm with fulcrum at B. C, electro-magnet. D, break. E, spring.
Fig. 26. A, piece of ribbon steel. B, point where circuit is broken. C, electro-magnet.
flow of the current. When we speak of a coil as, say a i2-inch coil, we
mean that the spark gap of that coil is twelve inches long; that its sec-
ondary current can be made to jump twelve inches of atmosphere. Coils
with parallel spark gaps from as narrow as about 6 inches to as long as
about 40 inches have been manufactured.
The induction coils manufactured today usually have a spark gap
of from 8 to 12 inches. (See pages 43 and 44.)
The wire of the primary winding is from about 16- to 4-gauge ; of
the secondary from about 34- to 29-gauge. The length of the wire in the
secondary is immensely greater than the length of the wire in the primary.
X-RAY MACHINES
29
Fig. 27. One-cell rectifier.
Fig. 28. Three-cell rectifier.
30
ELEMENTARY RADIOGRAPHY
At each "make" and "break" of the circuit of the primary current,
a current is induced in the secondary. The secondary current induced
at the break of the primary flows in the same direction as the current in
the primary, while the current induced at the make flows in the opposite
direction. Thus the secondary is an alternating current; but the current
of the make is so much weaker than the current of the break that, for,
practical purpose, the secondary may be considered a uni-directional, pul-
Fig. 39. Twenty-nine button rheostat.
sating current. The current of the make is what is known as the inverse
current, and it is the effort of all coil manufacturers to make a coil giving
as little inverse current as possible.
The voltage of the secondary current cannot be determined ac-
curately. Authorities differ very greatly in their estimate of the number
of volts required to jump one inch of atmosphere, giving the figure as
low as 10,000, and as high as 60,000. What voltage is required to jump
each succeeding inch after the first, is also a question shrouded in very
great uncertainty.
Estimating each inch of atmosphere at 10,000 volts, which perhaps
is getting as near the truth as possible at the present time, the voltage
X-RAY MACHINES
31
furnished by any size coil can easily be determined. Figuring on this
basis, an 8-inch coil in full operation supplies a current with a potential
of 80,000 volts; a 20-inch coil, 200,000 volts.
The amperage, or, to be more exact, the milliamperage of the sec-
ondary current of an induction coil varies according to the resistance
Fig. 30. Diagram of rheostat.
through which the current is forced. Thus, allowing the rheostat to re-
main on the same button, the milliamperage is increased or decreased
accordingly as the spark gap (Fig. 17) is shortened or lengthened. With
the spark gap at its maximum length, the milliamperage is least. As the
sliding rods are pushed closer to one another, so lessening the length of
the spark gap, milliamperage increases. Different coils are capable of
forcing different milliamperages through their maximum length of spark
gap. Thus one lo-inch coil may be able to force twenty milliamperes
3^
ELEMENTARY RADIOGRAPHY
through ten inches of atmosphere, while another could send only two
milliamperes through such a resistance. All coils give a high milliam-
perage on a short spark gap, the amount running into hundreds of mil-
liamperes. Instead of the sliding rods, some coils have an arrangement,
as per Fig. 34, fcir regulating the length of spark gap.
The milliamperage strength can be estimated roughly by the ap-
pearance of the spark. A thin, blue spark indicates low amperage. A
Mains
Coi/l
Fig. 31.
fat, fuzzy spark, the caterpillar spark, indicates high milliamperage. To
do rapid dental radiographic work a coil should give at least six inches
of the fat, fuzzy spark.
Amperemeters and milliamperemeters are used on the primary and
secondary currents, respectively, to measure their volume. (Fig. 13.)
While these meters may be considered luxuries rather than necessities,
they are certainly very useful luxuries.
X-RAY TUBES AND THE X-RAYS
33
Fig. 32.
A, iron core. B, iron core with primary winding. C, iron core, primary winding and insulation.
D, iron core, primary winding, insulation and secondary winding.
Now let us consider the high-frequency coil.
Ulflb-TrCflWency (Figs- 14 and 35.) In mechanical construction the
€Oil. high-frequency coil may be considered a kind of
double coil with the secondary of the first coil act-
ing as the primary of the second coil. The primary current of the first
coil should be A.C.
34 ELEMENTARY RADIOGRAPHY
From the supply wire the current passes through the primary wind-
ing of a step-up transformer (first coil) at the usual commercial lOo to
125 volts, 60-cycle. (Fig. 35.) An alternating current of the same
frequency as the primary, but higher in voltage and lower in amperage
is generated in the secondary of the transformer, and passes into the
condenser, which acts as a reservoir. As the current leaves the condenser
and jumps the regulating spark gap, it is oscillating at a frequency of
'A
B
C
Fig. 33
Cross-section diagram of induction coil. A, iron core. B, primary winding. C, insulation.
D, secondary winding.
from 10,000 to more than a million. It passes through the primary wind-
ing of the Tesla coil, inducing a secondary current of the same high
frequency. This Tesla coil is the same as an induction coil (Figs. 32 and
33), except that some inert substance, instead of soft iron, is used for
the core.
The secondary current of the second coil is the one supplied by the
machine, the one to be used to generate X-rays. Like the current of the
Ruhmkorff, or induction coil, this current is high in voltage and low in
amperage. The current of the induction coil is, however, practically a
uni-directional one, while the current supplied by the high-frequency coil
is alternating at the inconceivably high frequency of tens of thousands
or millions. Hence the term "high frequency," which is applied to the
current and the coil producing it.
The frequency is governed by the size of the condenser; the smaller
the condenser the higher the frequency. Thus most "high-frequency and
X-ray machines" are equipped with a switch, by means of which all, or
X-RAY MACHINES
35
a part, of the condenser may be used. When using the coil for X-ray
work, this switch should be turned to "low frequency," so that all of the
condenser is used. When using the coil for "high-frequency" treatments
— using the current as a therapeutic agent — the switch should be on "high
frequency," so that only a part of the condenser is used.
By means of the regulating spark gap, we can control to an extent
the secondary current of the second coil — the current supplied by the
Fig. 34.
machine for use. Widening the gap increases voltage at the expense of
the amperage ; narrowing the gap increases amperage at the expense of
the voltage. The wattage remains the same. For X-ray work the gap
should be as short as possible, without reducing the voltage to a point
where the current will not pass through the X-ray tube.
High-frequency or Tesla coils are often spoken of as " suitcase coils "
and " portable coils," because they are frequently built in the shape of a
suitcase and are transportable.
Some coils of this type are mere toys, incapable of doing good dental
work, while others compare favorably, on the A.C. circuit, with small and
medium size induction coils. One should be cautious, therefore, when
purchasing a coil of this type.
36
ELEMENTARY RADIOGRAPHY
As stated, the primary, or supply, current of a coil, built on the high-
frequency plan illustrated, should be A.C. When attaching the portable
coil (Fig. 14) on an A.C. circuit, therefore, all that needs to be done is
to screw the attachment into a lamp socket.
Terminal Sparh Gap
(Ab? rejalatinj Spark ^ip)
^nd Coil F^
Tesla. Coil '~^
Spark (s3.p
+3
Comien^er
PJGoil
or
Step -Up
Transformer
^econda-ry
Prtma-fy
Fig. 35.
Kotary
Converter.
When the supply current is D.C., a rotary con-
verter should be used. A rotary converter (Fig. 36)
consists of an electric motor set in motion by the
supply current, which motor in turn revolves the
armature of an A.C. dynamo, which generates the electricity that is sent
into the coil. Instead of having the D.C. motor and the A.C. generator
as separate machines connected by a common shaft, so that movement of
the armature of one machine revolves the armature of the other, the
rotary converter can be made so as to be enclosed in one casing. (Fig. 15.)
Tracing the current, as per Fig. 37, coming through the fuse and
switch, the current pagses through the positive wire to the starting box
X-RAY MACHINES
37
or rheostat. It leaves the starting box through two wires, passing
through one to the field of the motor marked S.F., through the other to
the armature of the motor, marked ARM, and out of the motor through
the negative lead wire. A new circuit is formed from the generator side
of the converter marked A.C., passing through the coil.
It may be well to state just here that an electric motor is, in con-
struction, practically the same as a dynamo or generator. In fact, taking
Fig. 36. Rotary converter, or motor-dynamo.
a given machine, it may be used as either a dynamo or a motor. If its
armature is revolved by some power, it will generate electricity, and it
is then a dynamo ; if a current of electricity is sent into its field and
armature, the armature revolves ; and it is then an electric motor. Motors
are made to be operated by both D.C. and A.C. circuits ; that is, we have
D.C. motors which can be run only by a direct current, and A.C. motors
which can be excited only by an alternating current.
Instead of a rotary converter, some machines are equipped with a
mechanical vibrator (Fig. 22), which interrupts the current as it enters
the coil. This is not so efficacious as the converter. Machines with the
mechanical interrupter are advertised to operate on either A.C. or D.C.
circuits.
The length of the spark gaps of portable machines varies from four
to ten inches. They are seldom able to give a fat, fuzzy spark longer
than half the length of the spark gap. The full-length spark is almost
always thin and blue.
38
ELEMENTARY RADIOGRAPHY
Tnterruptcrlcss
€oi1$ or
transformers.
The interrupterless coil, or transformer, as it is
usually designated now, is the newest, the easiest to
operate and the most powerful X-ray machine thus
far made. Comparatively little space is needed to ex-
plain the principle of its construction, since it will not be necessary now
for me to define and explain such common electrical apparatus as fuses,
switches and the like, as it was in the description of the induction and
high-frequency coils.
Line,
110 Direct Current.
Portable Coil.
converter
Fif
The transformer X-ray machine consists of a rotary converter, or
synchronous motor, a step-up transformer, and a rectifier switch. (Fig.
38.) The step-up transformer may be of the closed magnetic circuit
core type (Fig. 38B), or the open core type (Fig. 38A). These machines
are of two kinds : those built to be operated on a D.C. circuit, and those
designed for the A.C. circuit.
Let us consider the former first : The converter is set in motion by
the commercial direct current. It generates an alternating current which ■
is sent through the primary of the transformer. The induced current in
the secondary is of the proper voltage and amperage for X-ray work,
but it is alternating. It should be direct. It is made so by means of the -^
X-RAY MACHINES
39
rectifying switch, and is then an ideal current for X-ray work. The rec-
tifying switch is a revolving mechanical device similar to a commutator
In principle.
Instead of a rotary converter the A.C. machine has an A.C. motor,
on the shaft of which is the rectifier switch. From the mains, four wires
ZQ
T.Q-A- ,4
0^ TRKULUtL 1
fiQ- 56
Fig. 38. Didactic drawing of the transformer or interrupterless X-ray machine. " A " the D.C.
machine. " B " the A.C. machine. To trace the current, follow the arrows by number.
lead to the A.C. machine ; two for the motor, two for the transformer.
First the motor is set in motion. Then the current may be turned into
the primary of the transformer and an alternating current is immediately
generated in the secondary winding. This secondary, alternating current
is of the proper voltage and amperage for X-ray work, and is made uni-
40 ELEMENTARY RADIOGRAPHY
directional by passing it through the rectifier switch. In order for the
rectifier switch to change the alternating current into a direct one it must
revolve at a definite rate of speed, in perfect synchronism, or step, with
the rapidity of alterations of the alternating current. Because of this,
the motor is spoken of as a synchronous motor.
The first interrupterless coils to be made for the alternating current
had an A.C. motor connected with an A.C. generator. But two main
wires lead to this type of machine. The motor is set in motion with the
supply current. The shaft of the motor extends to the generator, revolv-
ing its armature. The current produced by the generator passes into
the primary winding of the coil, and the secondary, induced, alternating
current is made direct by passing through the rectifier switch which is
attached to the shaft of the generator and therefore moves in synchron-
ism with it. It was necessary to build interrupterless coils for the A.C.
circuit in this manner until motors were produced which revolve the rec-
tifier switch in synchronism with the line or supply current.
The greatest shortcoming of the transformer type of coil has been
the difficulty in making one with sufficiently high voltage to do certain
kinds of X-ray work as well as the induction coil. This shortcoming,
however, has been quite satisfactorily overcome.
The interrupterless coils are rated according to the amount of " en-
ergy " they create, not according to their spark gap length. The spark
gap is usually ten or twelve inches long. The machines are rated to have
a capacity of so many kilowatts. Take a " 4 kilowatt " machine, for ex-
ample. Its primary current, we will say, is 100 volts, 40 amperes (4,000
watts), the secondary current something like 100,000 volts, 40 milli-
amperes (4,000 watts).
This system of rating is being adopted by manufacturers of induction
coils also. (See pages 43 and 44.)
CHAPTER III.
X-Kay tubes and the X-Kay$.
Thus far we have considered only the electric phase of the subject.
We shall now describe the apparatus through which the electricity is
passed, and which generates the X-rays, namely the X-ray tube.
An X-ray tube is a bulbular glass tube, from which the atmosphere
has been exhausted to quite a high degree of vacuum — about 1/1,000,000
part of an atmosphere. It should be remembered that there is a some-
thing which occupies all space, even vacuua, and that something is known
as ether. There is, of course, ether in the X-ray tube. X-ray tubes are
often called Crooke's tubes, but they resemble the tube made by Pro-
fessor Crooke only in having a high degree of vacuum. In mechanical
construction they are quite different.
Tubes may be divided, according to the machines
Classification on which they are used, into the static machine tube,
Of X-Ray Cubes. the induction coil tube, the high-frequency coil tube
and the transformer tube.
Since we have eliminated the static machine from consideration be-
cause it is obsolete we will likewise eliminate the static machine X-ray
tube and describe first the induction coil tube. For a description of the
Coolidge tube see index.
In describing the tube used with induction coils
TnaUCtion ^g of necessity, consider the fundamentals of all X-
* ray tube construction and X-ray production.
Sealed in the X-ray tube are the anode, Fig. 39, A (also called anti-
cathode and target), and the cathode, B. The anode is usually flat,
placed at an angle of 45 degrees to the long axis of the tube, and made
of some high-fusing metal, such as tungsten, platinum, iridio-platinum
or tantalum. The cathode is concave, saucer shape, and usually made
of aluminum.
Since, in connecting the tube to the coil, it is necessary to attach the
connecting terminal tape or wire from the positive side of the coil to the
target end of the tube, we must be able to determine which is the positive
terminal of the coil. This may be done on an induction coil, as follows :
Cut out the resistance of the rheostat, adjust the sliding rods to about
one-half the distance of the maximum spark gap, and throw on the
switch. The spark will jump the gap so quickly that it is impossible to
learn by simple observation in which direction it is traveling. By watch-
41
42
ELEMENTARY RADIOGRAPHY
mg the large disc terminal, however, this can be determined. If on
throwing the switch on and off the spark is noticed to cling to the edge
of the disc ahvays, then the current is passing from the disc. If, how-
ever, the spark occurs from the surface of the disc just as the current is
turned on (it may then seek the edges), the current is traveling from the
small bulb to the disc. (Fig. 40.)
With the tube properly connected to the coil as per Fig. 41, the
current is shunted (Fig. 42) through the tube, instead of jumping the
+
cC
Fig. 39. A, anode. B, cathode. C, point at which the atmosphere was pumped from the tube.
spark gap, passing from anode to cathode. Whether the current will
choose the path through the tube or jump the spark gap depends on
which offers the less resistance. A current of electricity always travels
the path of least resistance.
^, .^, . ^ Tubes are designated according to the degree of
Classification of . . „, ^ , ^u u- u u a ^ u
X-Rav tubes their vacuum. Thus we have the high or hard tube,
Hccordiltfl to Degree in which the vacuum is well-nigh complete ; the me-
Of Uacuttm dium tube in which the vacuum is less complete, and
the soft or low tube, in which the vacuum is least complete. High tubes
offer the greatest resistance to the passage of the electric current through
them, then comes the medium, while the low vacuum tube offers the least
resistance. For dental picture work a medium tube yields excellent results.
The operator may determine whether a tube is hard, medium or
soft, as follows: Connect the tube to the coil. (Fig. 41.) Separate the
sliding rods to give a spark gap of two or three inches and turn on the
current. Unless the tube is very low indeed, the current will jump the
spark gap instead of passing through the tube. Let us suppose the cur-
X-RAY TUBES AND THE X-RAYS
43
rent does jump the spark gap. Now widen the gap a little; turn on the
current, and it passes through the tube. The tube will, therefore, be
rated as one of low vacuum, offering a resistance slightly greater than
two or three inches of atmosphere. When the current jumps the spark
gap instead of passing through the tube, the tube is said to have "backed
up" so many inches — the number of inches of the gap — of "parallel
spark." Thus a low tube will back up two or three inches of parallel
A
«^
r
A
A
4-
A
i^^ >
Fig. 40.
Spark; a medium tube will back up four or five inches of spark; a high
tube will back up six or seven inches of spark, and a very high tube will
back up eight or nine inches of spark. Very high tubes offer so much
resistance that only the largest coils are able to force sufficient milliam-
perage through them to generate a sufficient number of X-rays for picture
work. A tube that will back up more than nine inches of spark is too
high to be useful ; it is impossible to force enough milliamperage
through it. The best back up for dental work is about 5 inches.
From the foregoing it will be seen that any coil smaller than one
with a 7 or 8-inch spark gap could not well excite a high tube, and that
at least a ten-inch coil is necessary to light a very high tube. It seems,
too, that any coil with a spark gap wider than eight or ten inches is need-
lessly large. The coils with the long spark gaps are, however seldom
able to throw a fat, fuzzy spark farther than eight or ten inches. The
.throwing of a thin, blue spark a greater distance is simply incidental and
44
ELEMENTARY RADIOGRAPHY
without practical usefulness. Thus an eight or ten-inch coil may be as
powerful as one with an eighteen or thirty-inch spark gap; that is,
capable of forcing as high a milliamperage through a high tube. If,
however, a coil can force any kind of a spark at all through from eighteen
to thirty inches of atmosphere, we may be sure it will send a high milliam-
perage through a good radiographic tube, or, what is the tube's equivalent
Fig. 41. The X-ray tube connected with the induction coil.
in resistance, six or eight inches of atmosphere. It is so well understood
to-day that the coil with the very wide spark gap is not necessarily more
powerful, that manufacturers are making practically all of their coils
with from an eight to a twelve-inch spark gap, then rating them ac-
cording to the milliamperage they can force through this resistance.
To light a tube well a coil should be capable of giving a fat, fuzzy
spark, the distance of the parallel spark which the tube backs up.
The tube thus far described is the simplest form of X-ray tube, and
no longer in general use. Next in simplicity is the bi-anodal tube. (Fig.
43-)
When the two anodes are connected, as in Fig.
Bi-anodal 43. the positive terminal may be attached to either
tubes. anode or assistant anode, preferably the anode. The
advantage of the assistant anode is a matter on which
authorities have widely different opinions. One manufacturer, a man
X-RAY TUBES AND THE X-RAYS
45
who is making one of the very best tubes on the market, tells me that he
puts the assistant anode in his tubes because some of his customers de-
mand it, and he is able to do so without impairing their efficiency; that
his tubes would be just as good with but one anode. Remember the
vacuum of an X-ray tube is not perfect ; there are some gases in the tube.
The function of the assistant anode is to draw these gases back of it
away from between anode and cathode. Thus, if the removable wire
m-
RESISTANCE
nAAAAAWWA
m^
^
THE SHUNT
Fig. 42. The arrows show the current flowing through the shunt.
connecting the anode and assistant anode (Fig. 43) be removed and the
tube hitched to the coil, the positive terminal being attached to the anode,
the tube will work with a slightly lower vacuum, because the assistant
anode does not draw gases back of it. Tubes with assistant anodes are
supposed to be capable of transmitting a greater milliamperage.
In the past tubes were classified as tubes with a means of regulating
vacuum' (Fig. 44) and tubes without a means of regulating their vacuum
(Figs. 39 and 43).
Tubes without regulators are no longer in general use, because, with
use, they soon become too hard, and must be sent back to the manufac-
turers to be opened and repumped. This is expensive and annoying. A
tube too high for use will sometimes drop in vacuum and regain its
former usefulness if allowed to rest — remain unused — for a month or so.
There are different methods of regulating the
111(t1)0d$ of vacuum of X-ray tubes. The most popular is the
Kcgulatins one we shall now consider.
Uacuum. The vacuum is governed by means of a movable
arm, which increases or decreases the distance be-
46
ELEMENTARY RADIOGRAPHY
tvveen A and B, Fig. 44. This distance we shall call the tube-regulating
spark gap. The shorter the gap the lower the vacuum can be made ; that
is, the shorter the gap the less perfect the vacuum can be made.
The current enters the tube and, let us imagine, tries to pass from
anode to cathode. The vacuum in the center of the tube is more perfect
REMOVABLE
WIRE
ASSISTANT
"ANODE
>
CATHODE
ANODE
Fig. 43. A Bi-Anodal X-ray tube.
REGULATING CHAMBER
Fig. 44. X-ray tube with vacuum regulator.
than around the walls. Hence the path of least resistance Is through the
regulating chamber, through the movable arm, through the tube-regu-
lating spark gap, into the negative terminal tape; unless, of course, the
tube-regulating spark gap is very wide.
X-RAY TUBES AND THE X-RAYS
47
Fig. 45. Showing the manner of connecting the third terminal on the coil with the
regulating chamber.
The regulating chamber contains asbestos impregnated with some
chemical, sodium or potassium hydrate, for examples. When the current
passes through the regulating chamber, heat is created, which causes the
chemical to give off gases. These gases lower the vacuum of the tube,
so that the current may pass directly from anode to cathode. When the
48
ELEMEN TA R Y RADIO GRAPHY
tube cools thoroughly — in the course of fifteen to thirty minutes — these
gases are taken up again by the chemicals in the regulating chamber,
and the vacuum rises again. Thus the vacuum of the tube may be too
high when the tube is not in use, but can be lowered to the desired
degree. Ordinarily the tube-regulating spark gap should be three
CATHODE
STREAM
Fig. 46. Showing the direct X-ray and the cathode stream.
to five inches. As the tube gets old the tube-regulating spark gap must
be made shorter to obtain the same condition of tube.
When the tube is properly hitched to the coil, and the movable arm
set for a high vacuum — to give a regulating spark gap of about four
inches — and the current turned on, practically all the current may at first
pass through the regulating chamber and jump the tube-regulating spark
gap. As explained, this lowers the vacuum, and in a few seconds the
current is passing from anode to cathode. All of the current may pass
directly through the tube now for a few seconds, but the passage of the
current from anode to cathode raises the vacuum and presently some
current will be seen to jump the gap for a while. And so on, just as the
vacuum raises a little, it is immediately lowered by some of the current
passing through the regulating chamber.
X-RAY TUBES AND THE X-RAYS 49
Instead of the movable arm, a terminal tape and a third terminal
on the coil may be used. (Fig. 45.) Thus the tube-regulating spark is
transferred from the tube to the coil. The hitching of a tube to a coil
with a third terminal is very simple. Hitch the positive terminal to the
anode, or assistant anode if desired, and the negative terminal to the
cathode, as usual ; and the third terminal to the regulating chamber. The
advantages of the third terminal over the movable arm are that the spark-
ing is taken away from the tube and so away from the patient (in radio-
graphic work the tube is always near the patient), and, on some coils,
Fig. 13 for example, the gap may be regulated from the end of the coil
where the rheostat and switches are located, so making it unnecessary
for the operator to move from his position to change the tube-regulating
spark gap.
When the current passes from anode to cathode, the cathode
stream (Fig. 46) is given off from the cathode. The cathode stream
is a form of vibratory motion of the ether. Leaving the concave surface
of the cathode, the cathode stream is focused to strike the anode or target
at a point. X-rays are given off from this point (Fig. 46). The cathode
stream can be seen in a tube of very low vacuum, appearing blue.
Great heat is generated at the point on the target where the
cathode stream strikes it. Hence the necessity of making the target of
some very high fusing metal. A small hole may be burned superficially
into the target without spoiling the tube. The tube in Fig. 47 has a
long sheath of metal connected with the target to take up the heat. Tubes
are made with a means for cooling with water. These are intended for
treatment rather than picture work, though they may be used for the
latter.
X-rays were discovered by William Conrad Roentgen, professor of
physics'" at the Royal University of Wurzburg, Germany, in the summer
of 1895. Roentgen applied the name X-rays because he did not know
just what he had discovered ; X, the algebraic symbol for the unknown,
being adopted to signify this ignorance. They were not called X-rays
because the rays cross, forming an X, as is popularly supposed.
The Roentgen Congress, in Berlin, 1905, adopted a uniform set ot
technical terms in which the word Roentgen always occurred. Thus we
have the phrase Roentgen ray for X-ray and such words as Roentgen-
ology, Roentgenologists, Roentgenogram, etc., etc. While approving of
a move for a uniform nomenclature, many of the new words are long
and unwieldy and the writer shall, in this work, use many of the old and
better-known terms.
X-rays are mvisible, vibratory waves of or in the ether. The most
so
ELEMENTARY RADIOGRAPHY
popular theory is that they are hght waves with an inconceivably rapid
rate of vibration. Red light rays vibrate at the rate of four hundred
billion per second; violet rays vibrate at the rate of seven hundred and
Fig. 47. X-ray tube properly lit up.
Fig.
X-ray tube with the current passing through it in the wrong direction.
fifty billion per second. The intermediate colors — blue, green, yellow and
orange — vibrate at intermediate degrees of rapidity.
Though human vision is limited to about three hundred and fifty
billion variance, the difference between four hundred billion and seven
hundred and fifty billion, may we not fairly assume that there are light
X-RAY TUBES AND THE X-RAYS 51
rays of a higher and lower vibration invisible to us? Ultra-violet rays
have a more rapid vibration than violet rays, and have no action on the
retina, and are therefore invisible. X-rays vibrate more rapidly than
ultra-violet rays. The rapidity of their vibration is estimated at 288,-
224,000,000,000,000* (two hundred and eighty-eight quadrillions, two
hundred and twenty-four trillions — French notation) per second.
Fig. 49. The inverse spark gap on the left is open, on the right is closed.
As just mentioned X-rays are invisible ; in fact, they are not discerni-
ble to any of the special senses. They pass from the focal point on the
target in regular, diverging lines (Fig. 46). When they strike an object
they are absorbed by it or pass through it. Broadly speaking, it may be
said they penetrate objects inversely, according to the density of the ob-
ject. They cannot be refracted or condensed, and the fact that they can
be reflected is of academic interest only since they are not reflected except
under what I should call experimental conditions.
The passing of the X-rays through the glass of the tube gives rise
to a green fluorescence (green light) in the active hemisphere — the hemi-
sphere in front of the target — of the tube. Whether a tube is working
well or not can be determined by this fluorescence. There should be a
definite line of demarcation between the active and inactive hemispheres
of the tube. A tube working properly should light up as per Fig. 47.
The light is never quite steady; it wavers a little. High, medium and
low tubes give slightly difi^erent fluorescences when in operation. The
fluorescence from a high tube is a very light yellowish green ; from a low
duster's "Dental Electricity
52
ELEMENTARY RADIOGRAPHY
tube a bluish green and from a medium tube an intermediate shade of
green.
Just here let it be said that an exact colored picture of an X-ray
tube in operation has never been made. I obtained the services of an
artist and spent a great many hours on the work, but was unable to make
a picture worthy of reproduction. The light from an X-ray tube in
Fig. 50. Patent series or inverse spark .gap for positive terminal.
operation is of a peculiar brilliancy that cannot be reproduced in crayons,
water-colors, or ink.
When the vacuum of a tube is so low as to render it useless for radio-
graphic purposes, a definite blue color can be seen here and there in the
tube, the cathode stream can sometimes be seen appearing blue, and the
line of demarcation between the active and inactive hemispheres of the
tube is not well defined.
When a tube is punctured the vacuum gets very low, of course, and
its appearance in operation may be as just described, or, as sometimes
occurs, it gives rise to a fluorescence as variegated as a rainbow, or it may
not light at all. A punctured tube can sometimes be repaired by the
manufacturer.
When the vacuum of a tube is too high, the tube lights up reluctantly
a very yellowish green, and the line of demarcation is not at all distinct.
Fig. 48 illustrates fairly well the appearance of a tube with the
current passing through it in the wrong direction. When this condition
is seen the current must be turned ofif quickly, or the tube will be ruined.
Sometimes, when the tube is properly hitched to the coil, light rings back
of the target, similar to those shown in Fig. 48, may be seen. This
X-RAY TUBES AND THE X-RAYS
53
signifies that the coil is generating considerable inverse current. Recall
that, while the current generated by the induction coil is practically a
unidirectional one, there is an inverse current which is sometimes strong
enough to manifest itself as just mentioned, especially when the vacuum
of the tube is low.
Fig. 51. A triple valve tube.
It is not at all desirable to allow inverse current
Cutting Out to pass through a tube, for it gives rise to a scattering
Inverse generation of X-rays which interfere with the making
Current. of a clear X-ray picture. There are four moderately
satisfactory means of preventing the passage of in-
verse current through the tube.
The first and simplest means of eliminating inverse current is to make
what we shall call an inverse spark gap. (This gap is usually referred to
as the " series " spark gap because it is in series with the X-ray tube.)
The word series, so used, is a technical, electrical term, and fails to ex-
plain the function of the gap as well as inverse spark gap. The gap can
be seen between the positive terminal of the coil and the standard holding
the positive terminal tape reel (Fig. 49). A similar gap may be made
on the negative side. This gap cuts inverse current out of a tube by in-
creasing resistance to the point where the voltage of the inverse current
is not sufficient to jump the gap. Unless it is needed to cut out " inverse "
from the tube there should be no inverse spark gap ; the gap should be
closed as on the right, the negative, side of Fig. 49.
The second means of eliminating " inverse " is by the use of the
patent spark gap. (Fig. 50.) The current passes easily from point to
disc, but reluctantly from disc to point. Thus this series spark gap may be
used to cut out inverse current from a tube, with the points toward the
positive terminal tape and the points away from the negative terminal
tape. Fig. 50 shows the point toward the positive terminal tape. They
should be turned in the opposite direction at the negative terminal — away
from the tape.
54
ELEMENTARY RADIOGRAPHY
The third means of cutting the inverse current out of an X-ray tube
is by means of a valve tube. (Fig. 51.) The valve, or Villard tube, is a
tube of low, or, as it is often called, Geissler vacuum — 1/1,000 to 3/1,000
of an atmosphere — with a disc electrode and a spiral electrode, both made
of aluminum. The exact reason for its action is not known, but the elec-
tric current cannot travel through it well except in one direction — from
Fig. 52.
A
Fig. 53. An oscillimeter.
disc to spiral. Thus, to cut out inverse current the disc end of the valve
may be attached to the positive terminal tape of the coil, and, by means
of a piece of conducting tape, or wire, the spiral end connected with the
target side of the tube. Or the disc end of the valve may be attached, with
a piece of conducting tape, to the cathode side of the tube and the spiral
end of the valve to the negative terminal tape of the coil. (Fig. 52.) Fig.
83 shows a valve tube built into — i. e., as a part of — an X-ray tube.
Tt is claimed by some that the valve tube acts only as an additional
resistance to the flow of the inverse current, cutting it out of the X-ray
tube in the same manner that the inverse spark gaps do.
The fourth means of eliminating " inverse " from tubes is by what is
called a multiple inductance control on the induction coil. By means of
this control, which is found only on the more expensive coils, the output
current of the coil may be raised or lowered in voltage. If " inverse " is
seen in the tube the voltage should be lowered.
X-RAV TUBES AND THE X-RAYS
55
Oscillimetcr . ^^^ oscillimeter or oscilloscope (Fig. 53) is a
Geissler vacuum tube by means of which inverse cur-
rent may be detected when the X-ray tube is covered with an opaque
Fig. 54. The Meyer penetrometer.
Fig. 55. A fluoroscope.
shield. (Fig. 64.) I have never felt the need of it, though I have used
an opaque shield over my tube.
As has been stated, the X-rays are not discernible
Demonstration *-° ^^y °^ ^^^ special senses. Their existence, how-
Of X-Rays. ever, can be demonstrated as follows :
Place an X-ray tube in a wooden box so that
when the current is sent through it no fluorescence can be seen. Excite
56 ELEMENTARY RADIOGRAPHY
the tube in a dark room and approach it with some object coated with
calcium tungstate or platino-barium cyanide, and the object will be seen
to fluoresce or glow something like phosphorus. This fluorescence is
due to the action of the X-rays (which penetrate the wood of the box
easily) on the calcium tungstate or platino-barium cyanide. Hence the
closer the object to the tube the more and stronger the X-rays which
strike it, and the brighter the fluorescence.
Power of X-rays from different tubes differ in power of
Penetration penetration. A low tube gives the least penetrating
Of X-Rays. X-rays ; then comes the medium tube, while the X-
rays from a high tube are the most penetrating.
The degree of penetration may be determined by means of a pene-
trometer. (Fig. 54.) This particular kind of a penetrometer consists of
two small fiat pieces of wood fastened together, with a sheet of lead be-
tween them. Holes are made through both wood and lead. Into these
holes are placed thin metal discs which just fit the holes. The different
holes receive different numbers of discs.
To use this style of penetrometer we must have a fiuoroscope. A
fluoroscope (Fig. 55) consists of a light proof box, tapered and made to
fit over the eyes at one end, and covered at the other end with pasteboard
coated with calcium tungstate or platino-barium cyanide. If one should
look into the fluoroscope holding it toward ordinary light nothing could
be seen — one would look into perfect darkness. But if the fluoroscope
should be held so that the X-ray struck its screen — i. e., the pastboard
covered with calcium tungstate or platino-barium cyanide — it would be
seen to fluoresce, or glow, or light up.
If now the penetrometer is held between the fiuoroscope and the
source of the X-rays a shadow will be seen on the screen, because the
lead in the penetrometer is opaque to X-rays. Whether the X-rays will
penetrate the metal in the holes depends on how much metal there is to
penetrate and how penetrating the X-rays are. Thus the more penetrat-
ing the rays the more holes can be seen.
There are a great many different kinds of penetrometers. I shall
not describe them here, but will give the scale of the two most popular,
the Benoist and the Walter, together with that of the Meyer (Fig. 54).
Benoist. Walter. Meyei
Soft, or low tube i — 2 i i — 2
Medium 3—5 2—3 3—4
Hard or high 6 — 12 4 — 6 5 — ^lO
X-RAY TUBES AND THE X-RAYS
57
While the penetrometer is a very valuable appliance, it is far from
being a necessity in the practice of dental radiography.
As X-rays pass through the glass of the tube
Secondary more X-rays are generated. These are known as
l^ays. "secondary rays." They are short and feeble and do
not travel parallel with the direct X-rays, but pass
Fig. 56. High-frequency X-ray tube.
Fig. 57. High-frequency X-ray tube.
out from the tube in every direction intersecting the direct rays. Second-
ary rays are also given oil from any object which X-rays strike. Thus,
direct rays will strike a wall ; secondary rays are given off from the wall
and strike the other walls, the floor, and the ceiling, whereupon a new
set of X-rays, tertiary rays, are produced. When the tertiary rays strike
an object still another set of X-rays are generated, and so on, each new
set of rays being much shorter and weaker than the former. So a room
in which an X-ray tube is excited is filled with X-rays — not with the
direct rays, but with the comparatively feeble and inconsequential sec-
ondary, tertiary and other subordinate rays.
58
ELEMENTARY RADIOGRAPHY
Classification of X-ray tubes are of different sizes. The bulb
X-Kav tubes varies in diameter from five to eight inches. Thus
JlCCOrdittd to %m, ^e have the five-inch tube, six-inch tube, and so on.
The six-inch tube is about right for dental work.
With use the glass of the active hemisphere of the tube discolors to
a purplish color. This does not materially affect the tube.
The fatal injury to most tubes is a puncture. One means of guard-
ing against punctures is to keep the tube clean. "A fruitful cause of
Fig. 58. Tube rack for tubes when not in use.
puncture is the discharging of the current from the tube into the rack on
which the tube is kept when not in use. The tube may have been dis-
charged by the operator touching the terminals before putting the tube
away, but if the tubes are stored in the same room where high-frequency
and other coil discharges are taking place, they will recharge themselves
from the atmosphere and discharge onto the rack, no matter of what
material the rack may be made. A safe way of putting away tubes is to
connect the anode and cathode terminals together by a wire during the
time the tube is at rest."
The general principle of construction of the
Rigb-Trcqucncy high-frequency X-ray tube (Figs. 56 and 57) are
X-Ray Cube, those already given in the description of the tubes
built to be operated by a unidirectional current. The
X-RAY TUBES AND THE X-RAYS
59
chief difference between the high-frequency tubes and those already de-
scribed lies in the different means resorted to in the former to dispose of
one direction or wave of the alternating current, or, to speak more def-
initely, one cathode stream.
Fig. 59. Fig. 60.
Fig. 59. Plain X-ray tube stand.
Fig. 60. Tube stand, with a lead glass protection shield and a compression cone.
Either end of a high-frequency X-ray tube may be connected with
either terminal tape of a high-frequency coil. While this is theoretically
true, it will sometimes be found in practice that the tube works better
hitched up one way than the other.
When the tube is hitched up the current oscillates through it and
two cathode streams are generated. One of the streams is focussed
against the target and X-rays are given off from the focal point, while
6o
ELEMENTARY RADIOGRAPHY
the other is focused into a funnel in the back of the target. (Fig. 56.)
X-rays cannot be given off from this funnel; hence the tube lights up in
the active hemisphere as illustrated in Fig. 47. This funnel scheme is
Fig. 61. \ pedestal, with a lead glass protection shield, compression cone and plate holder.
one way of taking care of one cathode stream while the other is being
used for X-ray production. Another scheme is to move one cathode back
so far that the cathode stream focuses before reaching the back of the
target. (Fig. 57.)
The high-frequency tube may be used to advantage on an induction
coil which is generating a great deal of inverse current.
The transformer tube is almost identical in con-
transformcr struction with the induction coil tube. It is, however,
X-Ray tubes made to take a current higher in milliamperage and
lower in voltage; that is, the target is thicker and
the metax sheath leading from it heavier to take up the heat due to the use
of the high milliamperage, and the vacuum is normally a little lower.
X-RAY TUBES AND THE X-RAYS
6i
To avoid " straining " a tube, it should not be used again, after hav-
ing been used till hot, until it has cooled thoroughly. Overheating the
tube will destroy the gases in it, and so raise the vacuum to such a degree
as to make it impossible to force a sufficient milliamperage through it to
produce a sufficient number of X-rays. Sending a very strong current
Table, with a lead glass protection shield and compression cylinder.
through a tube of low vacuum will also destroy the gases of the tube and
spoil — strain — it.
Fig. 58 is a tube rack for holding the tube when not m use.
It is obvious that there must be some kind of a device for holding
the tube when in use. This may be either a plain tube stand (Fig. 59),
or a tube stand with a lead glass, protection shield and a compression
62
ELEMENTARY RADIOGRAPHY
X-RAY TUBES AND THE X-RAYS
63
cone (Fig. 60), or a pedestal with a lead glass protection shield, compres-
sion cone, and plate holder (Fig. 61), ora table with a lead glass, protec-
tion shield and compression cylinder. (Fig. 62.)
Dr. Blum, of New York, uses a wall bracket fixture to support a
lead glass, protection shield and compression cylinder. The tube, one
of the water-cooled type, is seen fitting into the lead glass shield.
Fig. 64. A Protection Shield.
(Fig. 63.) This would be, I imagine, a very adaptable and satisfactory
apparatus.
A tube stand should be heavy enough to be firm and not allow any
vibration of the tube while in use. The parts coming in contact with the
tube must be made of an electric non-conducting material ; otherwise the
current would pass from the tube into them, so puncturing the tube.
The uses of the compression cone or cylinder are : (i) To cut out sec-
ondary and inverse current rays (Fig. 65). (2) To aid the operator in
directing the X-rays at the correct angle. (3) In general radiography, to
hold the patient immovable and compress the soft parts as when making
a picture of the kidney, for example.
A protection shield, often called a Friedlander's shield (Fig. 64),
which is opaque to X-rays except for the window or opening in it, and
which is used to cover X-ray tubes, also cuts out some, but not all, second-
ary rays given off from the glass of the tube. Thus if the X-rays from an
64
ELEMENTARY RADIOGRAPHY
X-ray tube are directed on a part through a diaphragm and cone or cylin-
der, only the direct rays strike the part, as in the diagram study shown in
Fig. 65. While, with the Friedlander shield, some of the secondary rays
Fig. 65. D D D, direct ray. S S, secondary ray. P P, part.
Fig. 66. D D D, direct rays. S S, secondary rays. P P, part.
might strike the part also. (Fig. 66.) The diaphragm is a piece of lead
with a hole in it, situated, as a removable part of the tube stand, between
the X-ray tube and the cone, cylinder, or square. (Fig. 328.)
CHAPTER IV.
making Radiographs.
The X-ray picture is variously called radiograph, skiagraph, Roent-
genograph, radiogram, skiagram and Roentgenogram. The word radi-
ograph is a combination of a Latin and Greek word meaning ray and
write or record. The word skiagraph (spelled also sciagraph) is a com-
bination of two Greek words meaning shade or shadow and write or re-
cord. The word Roentgenograph is a combination of a proper name.
Roentgen, and the Greek word meaning write or record. The terminal
gram occurring in the words radiogram, skiagram and Roentgenogram
— as well as the more common words such as telegram, program, epi-
gram, and others — is of Greek origin and denotes that which is written
or marked.
The use of the X-rays for radiographic work depends on two prop-
erties of the rays. First, they penetrate substances in direct proportion
to the density of the substance, and second, they affect the photographic
plate or film the same as white light does.
A photographic plate is a piece of transparent
PbOtOgrapbiC plate glass about an eighth of an inch thick, one
Plates, side of which is coated with an emulsion of
a silver salt, usually silver bromide, and gela-
tine, albumen, or collodion. The use of the gelatine, albumen or
collodion is simply to stick the salt to the glass. When a thin
coating of this emulsion has dried on the glass we have what is
called the photographic "dry plate." In appearance it is similar to trans-
lucent greenish-white glass, but on close inspection one is able to de-
tect that one side is a little less glossy than the other. The less glossy
is the coated side, also called the sensitive, the film, or the emulsion side
of the plate. The term "dry plate" is to-day an almost superfluous one,
practically all the plates used being dry plates. There is, however, a
photographic plate known as the "wet plate," but, since it is never used
in radiography, I shall not describe it.
65
66 ELEMENTARY RADIOGRAPHY
The dry plate is made in the absence of white light, put up in light-
proof packages, and so supplied to consumers. These packages must not
be opened except in a dark room, for the slightest exposure to a white
light will spoil them.
- The difference between the photographic dry plate and the photo-
graphic film is only that the plate is a piece of glass coated with a
silver salt, while the film is a thin sheet of transparent celluloid coated
with a silver salt. As with the plate, the sensitive side of the film is a
little less glossy than the uncoated side. The film curls slightly toward
the coated side, unless it is of the "non-curling" variety, when it is
straight, or may even curl slightly away from the coated side. One
method of making non-curling films is to coat the non-sensitive side with
gelatin without any silver incorporated in it.
X-ray pictures may be made on ordinary plates
Special and films made to be used in cameras. While this
X-tay Plates may be done, the results obtained are usually not
and films nearly so good as when special X-ray plates and
films are used. Special X-ray plates and films are
extremely sensitive — that is, easily acted upon by light — for, though the
X-rays have a wonderful power of penetration, their action on the silver
emulsion of the photographic plate is feeble compared to the white light
of day. To make them especially susceptible to the action of the X-rays
some X-ray plates contain some fluorescent substance in the silver emul-
sion. Multi-coated plates are plates which have been coated with more
than one coating of emulsion, one coat on another.
Special X-ray plates and films can be obtained from many photo-
graphic supply houses and from any X-ray equipment company. The
following is a list of the manufacturers who make special X-ray plates :
George W. Brady & Co., Chicago, 111. ; the Eastman Kodak Co. and the
Forbes Dry Plate Co., Rochester, N. Y. ; Cramer Dry Plate Co., St. Louis,
Mo. ; the Hammer Dry Plate Co., St. Louis, Mo. ; the Lumiere N. A.
Co., New York City, and the Ilford Mfg. Co., London, England. So far
as I am able to learn only two manufacturers make X-ray films: The
Eastman Kodak Co. and the Ilford Mfg. Co. Since the war it has been
difficult to obtain the Ilford film. A German film, the Schleussner film,
can no longer be obtained at all on account of the war.
I wish here to advise against buying large quantities of either plates
or films at a time. They deteriorate in a few months.
The making of a radiograph of the hand is one
CCCbniC of of the simplest operations in radiography, and for
ItlaKiltd that reason it will be described to teach elementary
Radiographs principles. The following technic of making a radio-
graph will, of necessity, be much broken into by
descriptions of materials and appliances used.
A 5 X 7-inch plate is about the right size to make a radiograph of
MAKING RADIOGRAPHS
67
the hand. Plates are supplied by the manufacturer packed in light-proof
boxes, holding usually one dozen plates, with the warning on the box.
"Open only in a dark room." The "dark room" is simply what the name
states — a room from which light is excluded. A closet without a window
makes a good dark room, except that there is seldom running water in it.
It is not absolutely necessary to have running water in the dark room,
but it is very convenient. If a closet cannot be utilized a room, light-
sr/f/f>
Fig. 67. To left, window ready for frame. When frame is in position the metal catches are
turned to hold it. The frame fits inside of the strip on the sill. Figure to right shows
frame in position.
proof except for one window, may be made dark by covering the window
with a frame on which is tacked some material such as the leather or
rubber used for side and storm curtains in buggies. If this material does
not completely turn the light, it should be painted with thick black paint.
The frame should be made to fit over, not into, the window casing. (Fig.
67.) With the frame so placed, if a little light comes in around it, it
does not come directly into the room, but is reflected to the side. The
more perfect the darkness of the room the better, but the very little light
68
ELEMENTARY RADIOGRAPHY
which can enter through a window with the bHnd drawn down, and with
a well-made frame over it will not cause any trouble. If the door to the
room permits light to leak in around it, such light should also be shut out.
It would be impossible, of course, to work to any advantage in a
perfectly dark room, for we could not see what we were doing.. Hence
the necessity of having a dark room lantern (Fig. 68), which will give
sufficient light to guide us in our work, without being of such nature as
to have any action on plates or films. The term "developing light" — the
Fig. 68. Dark room lantern.
light given by the dark room lantern — may mislead one to believe that
the light in some way aids in developing a plate by its action on it. But
such is not the case. The light is of value only because it enables the
worker to see. The light may be a candle, a coal oil lamp, or an incan-
descent electric light shining through red glass. While such a lantern
can easily be made, the writer warns against it, for, though the light of a
home-made lantern may appear the same to the eye as the light of the
lanterns manufactured by photographic supply manufacturers, its action
on a plate or film may be disastrously dififerent. The lantern shown in
Fig. 68 consists of a i6-candle power incandescent light with a frosted
glass bulb, in a light-proof tin box, the front of which is of removable
glass. The light shines first through the frosted glass of the bulb, then
an orange-colored glass, then a ruby glass.
In the dark room, with only the light of the dark room lantern we
MAKING RADIOGRAPHS
69
open our box of plates,* take out one. carefully close the box, and place
the plate in an envelope of black, light-proof paper just large enough to
receive it. Now place plate, black envelope, et al., in another envelope
of black or orange-colored paper, putting the open end of the first en-
velope in first. We may now expose this package to ordinary daylight
and artificial light with impunity, and the plate is ready for use in the
making of a radiograph. These envelopes are obtained from the plate
manufacturers.
Fig. 69. Showing how to handle a plate by its edges.
While in the dark room, before putting the plate in the envelope, we
must note which is the sensitive side, and bear this in mind until the
outside envelope is marked properly to designate it. As formerly stated,
the sensitive side is a little less glossy. Another way to determine which
is the coated side is to look through the plate just at the edge. When
the glass side is up, one is able to look through the glass and see the film
beneath. The sensitive side of the plate should present toward the
smooth side of the envelope — away from the seam side.
The plate should be handled by the edges. (Fig. 69.) This applies
to the handling of the plate at all times, and to the handling of the film
as well. Unless the fingers are wet or greasy, touching the sensitive side
*Experienced photographers prefer to handle sensitive plates in absolute dark-
ness, and soon learn to detect the film side of the plate bj' feehng hghtly with the
fingers, thus obviating the need of the dark room light when "loading" plates. — Ed.
70
ELEMENTARY RADIOGRAPHY
of the plate is not likely to result in spotting the picture, but it is always
well to eliminate as many chances of failure as possible.
We are now ready to arrange tube, hand, and plate in their proper
relative positions to take the picture. In all radiographic work it must
STA/^D
Fig. 70. Showing relative positions of tube, hand, and plate for making a radiograph of the hand.
constantly be borne in mind that we are making a shadow picture; that
we are simply throwing a shadow on the plate, using X-rays as the
source of light.
Lay the plate on a stand, sensitive side up. Place the hand on the
plate. Adjust the tube at a variable distance directly above the hand,
(Fig. 70.)
MAKING RADIOGRAPHS 7^
The distance from the tube to the plate may vary from about lo to
20 inches, measurements being taken from the target, not from the glass
of the tube. It is not necessary to have the target and the plate parahel
to one another (in the same plane) as some writers direct. On the con-
trary, the position as in Fig. 70 is a better arrangement.
Assuming now that the tube is properly hitched to the coil and work-
ing properly, we are ready to make the exposure — to take the picture.
In giving demonstrations, I find that at this point someone invariably
volunteers to "turn out the light." This is not necessary. The only
reason for having the rooms even slightly darkened is to enable the ope-
rator to observe how his tube is working. The picture could be taken in
bright daylight ; the envelopes will protect the plate against all light ex-
cept the X-rays. (See Chapter V for technic of lighting X-ray tube.)
When the switch is turned on and the X-rays produced, they, the
rays, shine down on the plate penetrating the paper of the envelopes as
though the plate were not covered at all. The rays penetrate the hand
also and act upon the plate beneath. They penetrate the bones of the
hand less readily than the flesh, and hence there is less action on the
plate directly beneath the bones. In other words, there is a shadow of
the hand thrown on the plate, the shadow of the bones being denser than
the shadow of the flesh. The shadow of the flesh, in fact, may be so
light that it is scarcely discernible, or even entirely blotted out. This is
the case when a very high tube is used and a long exposure made.
The length of time of the exposure of the plate
Duration of to the action of the X-rays when making a radio-
€xpO$urc. graph depends on several things, (i) The milliam-
perage sent through the tube. Other factors re-
maining the same, the more milliamperage sent through the tube the
shorter the exposure necessary, because the higher the milliamperage
sent through the tube the greater the number of X-rays produced.
A coil equipped with a milliamperemeter enables the operator to
observe the exact number of milliamperes passing through the tube.
(2) The nature of the X-rays. Other factors remaining the same,
the more penetrating the X-rays the shorter the exposure necessary.
The higher the vacuum of the tube up to a given point, the more
penetrating the rays from it. A low tube is useless for radiographic
work. (3) The distance of the plate from the tube. Other factors
remaining the same, the shorter the distance between the plate and
the tube the shorter the exposure necessary. (4) The thickness of the
part to be radiographed. Other factors remaining the same, the thicker
the part the longer the exposure necessary. (5) The density of the part
72
ELEMENTARY RADIOGRAPHY
to be radiographed. Other factors remaining the same, the denser the
part the longer the exposure necessary. (6) The sensitiveness of the
plate. Other factors remaining the same, the more sensitive the plate
the shorter the exposure necessary. The product of some manufacturers
is more sensitive than others. As a plate or film grows old it becomes
less sensitive, finally becoming entirely useless.
Fig. 71. Radiograph of the hand, made from a pose similar to Fig. 70. (Reduced one-half.)
It will be seen from the foregoing that so many things enter in for
consideration that the exact time of exposure cannot be stated with any
degree of clearness. Elaborate systems of calculation have been worked
out so that if the distance of the tube from the plate, the penetration of
the X-rays measured with a penetrometer, the milliamperage sent through
the tube, and the thickness of the part be known, reference can be made
to a printed table and the exact time of exposure necessary learned.
While commending such work as efiforts along the right line, I consider
them failures so far as practical application in dental work is concerned.
Notice that in the calculation the density of the part and sensitiveness of
the plate are not taken into account at all.
MAKING RADIOGRAPHS 73
Each man must learn to properly time his exposure by personal ex-
perimentation. This statement is likely to be contradicted by those who
construe it to mean that no idea at all of the time of the exposure can
be learned except by experiment. That is not what I am saying, however.
The idea I wish to convey is that these tables of calculation, on the time
of exposure, give only the approximate length of time necessary, and that
a very little experience and the use of judgment render them useless.
They are always useless except when a penetrometer is used and the coil
is equipped with a milliammeter.
Fig. 72. Trays for developing and fixing solution
To make a negative (the picture on the glass of the plate) like the
radiograph shown in Fig. yi, the factors may be as follows:
1. Machine used: A large induction coil, with a two-point elec-
trolytic interrupter, operating on iio-volt, D.C. circuit. Three-fourths of
the resistance of rheostat cut out.
2. Strength of current : Machine not equipped with ammeter or
milliammeter. Approximate amperage of the primary current, 20. Sec-
ondary current sufficiently powerful to obtain a fat, fuzzy spark 10 inches
long — an estimate, about 10 milliamperes.
3. Penetration of X-rays : Tube backs up 5 inches of parallel spark.
Distance of tube regulating spark gap 5 inches. Therefore, the tube is
medium high and the rays from it rather penetrating when it is properly
lighted. Benoist penetrometer 5.
4. Distance of target from plate: Twenty (20) inches.
5. Thickness of part: That of hand, about i/^ inches at thickest
part.
6. Density of part : That of hand.
7. Plate used : Paragon special X-ray plate. (An ordinary camera
photographic plate might have been used to take such a picture. Had this
been done, however, the time of exposure necessary would have been
about twice as long.)
8. Time of exposure of plate to action of rays : Two (2) seconds.
9. Time plate remained in developer : Five minutes.
74 ELEMENTARY RADIOGRAPHY
During exposure, the patient, tube and plate must be perfectly immo-
bile. After the exposure we are ready to " develop the negative."
Remove the plate from the envelope in the dark
method of room, exposing it only to the ruby light. It has not
Development. changed in appearance at all. It still looks like a
piece of translucent, white glass. But the picture is
there. It needs only to be developed.
This is done by immersing the plate, sensitive side up, in an aqueous
solution of chemicals, the developer. This developer causes that part of
the plate which has been acted upon by the X-rays to turn dark, but does
not cause that part of the plate which has not been acted upon by the X-
rays to turn dark. The degree of darkness produced by the developer
in the plate varies directly according to the extent of the action of the X-
rays on the plate.
Place the plate in the tray (Fig. 72) containing the developer with
the coated side up, quickly covering the plate with the solution. A conveni-
ent way to make certain that the developing solution covers all of the
surface of the plate immediately is to place the plate in the empty tray
(sensitive side up of course) and pour the developer, out of a tumbler,
over it. Expose the plate to even the light of the dark room lantern as
little as possible until development is well under way. Trays can be pur-
chased from any photographic supply house. Always use a tray suffi-
ciently large to easily receive the plate. The action of the developer will
be hastened and made more uniformly perfect by slightly raising, then
lowering, one end of the tray, and so moving the developer over the sur-
face of the plate.
The length of time it takes the image or " picture " to " come up " or
show varies according to the length of exposure. If the exposure has
been well timed and the developer used acts as the average developer
acts, neither very rapidly or very slowly, the image will appear in about
30 seconds ; if the exposure has been a little overtimed, the image may
appear in about 10 or 15 seconds ; if it has been a little undertimed, it may
take I or 2 minutes for the image to appear.
Developing is not completed as soon as the image shows. Sometimes
the image can be seen better by removing the plate from the developer
and holding it up to the ruby light. If the exposure has been well timed
the " high lights " will commence to appear (i. e., the plate will begin
to turn dark in places) in about 15 seconds, and, as just stated, the image
can be seen tolerably well in 30 seconds. If this is the case the plate
should be left in the developer about 5 minutes. From the foregoing we
MAKING RADIOGRAPHS 75
may make the following rule : Leave the plate in the developer about 20
times as long as it takes for the high lights to appear, or 10 times as long
as it takes for the image to appear. This is not an inflexible rule. Indeed,
no inflexible general rule can be made, because of the difference in the
action of different developers. Another rule is to leave the plate in the
developer until the image can be seen on the glass side of the plate.
The actual time of developing will vary: 2 or 3 minutes for over-
timed exposures; about 5 minutes for plates which have been well ex-
posed; 10 to 15 minutes for undertimed exposures. This applies to most
developing solutions. However, developers known as " slow " developers
require about 20 minutes for well-exposed plates, and the Brady, Paragon
developer, known as the " four-minute developer," requires only 4 min-
utes.
There are a very great many different developing formulas, any of
which may be used. In making up developers, chemicals should invariably
be dissolved in the order as named. The following are some of the most
popular developer formulas :
M — Q Developer *
Avoirdupois Metric System
Water 10 ounces = 300 c.c.
Metol 7 grains -^ i^ grammes
Hydrochinon 30 grains = 2 grammes
Sulphite of Soda (desiccated) no grains = 7 grammes
Carbonate of Soda (desiccated) 200 grains = 13 grammes
10 per cent, solution Bromide Potassium 40 drops = 40 drops
Hydrochinon Developer
No. I
Avoirdupois Metric System
Hydrochinon 300 grains 20 grammes
Sulphite of Soda 6 ounces 180 grammes
Water 48 ounces 1,440 c.c.
No. 2
Carbonate of Potassium 4 ounces 120 grammes
Water 32 ounces 960 c.c.
To Develop, take
No. I, 6 ounces (180 c.c.) ; No. 2, 4 ounces (120 c.c.) ; 10 per cent, solution
Bromide of Potassium, 3 to 10 drops. Mix.
*M — Q stands for "metal — quinol." In photography the word "quinol" is used
as an abbreviation for "hydroquinol." This is unfortunate, because quinol and
hydroquinol are different substances. There are several words and different spell-
ings of the same word used to designate the substance — hydroquinol. They are :
hydroquinon (spelled also hydroquinone) ; hydrochinol (spelled also hydrokinol) ;
hydrochinon (spelled also hydrochinone, hydrokinon, and hydrokinone).
y6 ELEMENTARY RADIOGRAPHY
Pyro Developing Formula
Pyrogallic Acid Solution
"^ Avoirdupois Metric System
Pyrogallic Acid i ounce 30 grammes
Sulphuric Acid 20 minims i c.c.
Water 28 ounces 840 c.c.
Soda Solution
Avoirdupois Metric System
*Carbonate of Soda (Anhydrous) 2 ounces 60 grammes
*Sulphite of Soda (Anhydrous) 3 ounces 90 grammes
Water 28 ounces 840 c.c.
To Develop, take
"A," I ounce (30 c.c.) ; "B," i ounce (30 c.c.) ; Water, 8 ounces (240 c.c). This
developer will then contain 1.56 grains Pyro per ounce.
The developer may be made and kept in stock solutions as above, if
desired. A better plan is to buy the prepared developing powders. They
may be purchased at any photographic supply store. The chemicals comic
in glass tubes or packages mixed in the proper proportions, and all that
is necessary to make the solution is to dissolve them in the quantity of
water (distilled or tap water either) suggested on the package. The
package or tube usually contains a sufficient quantity to make 4 to 8
ounces of developing solution. The advantages of this over mixing the
chemicals yourself are : First, the convenience and saving of time, and
second, only small quantities being made at one time, the developer is
used immediately, and is therefore always fresh when used.
A developing bath does not keep well in stock solution unless the
bottles are full and well corked. Even then discoloration and disintegra-
tion occur in the course of a month or so. It is always advisable to use
as fresh a solution as possible. Packed in the box with the plates will
always be found a formula for a developer recommended by the manu-
facturer of the plates. It is not at all necessary to use the particular
developer recommended.
During the hot summer months it is necessary
temperature. to use ice in the developer, ice water to make the
solution, or place the tray containing the developer
in another larger tray with ice water in it. If the developer is too warm
it will soften the emulsion, cause frilling at the edges, blistering and
fogging of the negative. The developer should be between 65 and 70
degrees F. If too cold, development takes place slowly, and the negative,
when finished, is pale and thin. I use tap water in the winter and have
no trouble due to improper temperature. In the summer, though, even
using ice water and ice, the work is often discouraging. If possible dur-
ing the hottest weather defer development until the cool of the evening.
*If crystals are used, double the quantity.
MAKING RADIOGRAPHS
77
When development is complete, remove the
Tixillfl. plate, dip it in clear water, then immerse it in the
fixing bath. The fixing bath is a solution of chem-
icals which dissolves out the unaffected silver. Leave the plate in the
fixer for two or three minutes after the milky appearance of the glass
side of the plate has disappeared. A plate must be removed promptly
from the developer as soon as development is complete, or the negative
will be overdeveloped, spoiled, but it may be left in the fixing bath for
hours longer than necessary without danger of spoiling the negative.
Fig. 73. Titubator.
It will not injure the plate to remove and replace it in the baths at
any time during developing or fixing.
The actual time required for fixing varies from 5 to 20 or 30 min-
utes. The thicker the emulsion the longer time it requires for fixing.
Movement of the fixing solution over the surface of the plate will hasten
78 ELEMENTARY RADIOGRAPHY
fixing. A titubator (Fig. y^)) is a machine on which the fixing bath tray
may be set, and the bath kept in constant movement over the plate.
When several negatives are being made at the same time, it is well
to use a fixing box (Fig. 74) instead of a tray. If the plates were piled
one on another in the tray, they would probably stick to one another and,
when pulled apart, the emulsion would be scarred. The plates stand on
end in the fixing box, fitting into grooves.
Hyposulphite of soda is the standard fixer. There are not a great
number of fixers, as there are of developers, to choose from. Hypo-
sulphite of soda and water alone will fix plates, but is not so efficacious
as when other chemicals are added to harden the emulsion.
Acid-Fixing Bath
Avoirdupois Metric System
Water 64 ounces 2 liters
Hyposulphite of Soda 16 ounces 450 grammes
Sulphite of Soda (Anhydrous) ^ ounce 20 grammes
When fully dissolved, add the following hardener :
Powdered Alum 1/2 ounce 15 grammes
Citric Acid 3^ ounce 15 grammes
A\ stock solution may be made as given in the foregoing formula, or
the prepared fixing powder purchased, and the fixing bath made by sim-
ply dissolving the powder in a stated quantity of water. There is nothing
secret about the formulas of the prepared fixing powders. They are all
practically the same as the formula given. The advantage in using them
lies in the saving of time and energy that would otherwise be spent
weighing chemicals. If prepared developing and fixing powders are used,
it will not be necessary to have a pair of scales for this work. A grad-
uated glass for measuring liquids will be all that is needed. During the
hot months, it is expedient — not necessary — to use a freshly mixed fixer.
If this is done the negative is less likely to frill or blister. Urllike the
developing bath, however, the fixing bath will keep without disintegra-
tion for months. If scum or sediment appears after standing for some
time, this may be removed by filtering the solution through filter paper
or cotton.
The temperature of the fixer should be at least as low as that of the
developer, and better lower, say about 50 degrees F.
When fixed, if the plate. is held up to the light (any light, for the
plate is no longer sensitive to light), the shadow of the bones of the hand
will appear as transparencies; the flesh shows a little less transparent
than the bone, and the balance of the plate will be opaque and black.
Thus the shadows show light, and where no shadow was thrown the plate
is dark. Hence the name negative which is applied to this picture on
the plate. The making of the positive picture on paper, the print, as it
MAKING RADIOGRAPHS
79
is usually called, from the negative will be described presently. The
plate is no longer sensitive to white light, and may therefore be exposed
to it any time after having been in the fixer a minute or so.
Great care must be exercised not to get any of the fixing bath into
the developer. A very little "hypo" will spoil the developer. It is well
to label the trays so that the tray used to hold the fixer one time will not
be used for the developer another. Or, instead of labeling the trays, a
black one may be used for the developer and a white tray for the fixer.
Fig. 74. Fixing box.
Fig. 75. Plate, or negative, rack.
When fixing is completed the negative must be
lUil$bing. washed in clear water to remove all "hypo" from it.
If the negative be placed in a tray, the tray in a
basin or sink and the tap turned on, or, in other wordc, if the negative
be washed in running water it requires 15 to 30 minutes to thoroughly
wash it. Where running water cannot be had,* and sometimes during
hot weather when tap water is too warm, the negative may be placed in
a larger vessel of water and left for about an hour, changing water sev-
eral times. A tray of water used on a titubator is efficient. The water
must be changed often, and the time required is about three-quarters of
an hour or longer. When several negatives are being made, it is ad-
visable to use a washing box similar to the fixing box. (Fig. 74.)
* "Runnii^g water" is much to be preferred, as the friction or movement of
the water is a great factor in cleansing the plate. After a few months if plates
show cloudiness, or a metallic luster is observed, this means that the plates were
not thoroughly washed. It is even advisable, after washing, to rub the surface of
the film side with clean, wet cotton, holding the plate under a faucet during the act.
8o ELEMENTARY RADIOGRAPHY
The nexty and the last step in the making of the
Drying. negative, is to dry it. The plate should be set on
edge. Drying should take place in a clean atmos-
phere, so that no dust or soot will fall on and stick to the coated surface
of the negative. Plate racks (Fig. 75) may be used, but are not a neces-
sity. The plate may be set on edge at an angle of about 95 degrees by
simply leaning it up against some perpendicular wall. (Fig. 76.) Dry-
Fig. 76. Negatives leaning against perpendicular wall, drying.
ing requires several hours. It may be hastened by placing the negative
in a breeze. By immersing the negative in a mixture of formalin and
alcohol, then placing it in the breeze of an electric fan, drying will be
very materially hastened. The use of the formalin and alcohol some-
times causes spotting and blurring of the negative. If all the salts of
the fixer are not well washed out of the emulsion, it will not dry prompt-
ly, but will become rough and sticky, and, when finally dry, it will be full
of little holes.
Summarizing the making of the negative, it consists of exposing,
developing (washing — mere dipping in water), fixing, washing, and dry-
ing.
If the negative when finished is very dark, so dark that parts of the
image are lost, the plate was either overexposed, or overdeveloped, or
MAKING RADIOGRAPHS 8i
both. I prefer usually to say that it was overdeveloped, for even if it had
been exposed unnecessarily long, this mistake might have been corrected
by leaving it in the developer a shorter length of time. If the negative
is almost entirely transparent and the image can hardly be seen, it is due
to underexposure, or underdevelopment, or both.
The mistake of overexposure or overdevelop-
KcdUCCrs. ment can be corrected to an extent by the use of a
"reducer."
The following solution is a reducer :
*A. Water 16 ounces (480 c.c.)
Hyposulphite of Soda 1 ounce (30 grammes)
B. Water 16 ounces (480 c.c. )
Potassium Ferricyanide 1 ounce (30 grammes)
Mix 8 parts of solution "A" and one part of solution "B," and use in subdued
light.
The i:!egative can be placed in this solution directly after fixing,
without washing. Or it may be washed — it makes little or no difference.
If a dry negative is to be reduced, it must be soaked in water for at least
half an hour before placing it in the reducer. When sufficiently reduced,
wash thoroughly for about three-quarters of an hour, then dry. The
work of reducing may be done in any light.
When not in use keep solution "B" protected from the action of
light. Remember that this solution is one of the most powerful poisons
known. Handle it with extreme caution.
The mistake of underexposure cannot be cor-
TntcnsifiCI*. rected to an appreciable extent by any means.
The mistake of an underdevelopment can be
corrected to an extent by the use of an "intensifier."
After having fixed the negative, wash it well in running water for
about thirty minutes or longer, then place in the following solution :
Mercuric Bichloride 200 grains (13.3 grammes)
Potassium Bromide 120 grains (8.0 grammes)
Water 65^ ounces (195 c.c.)
Keep the plate in this solution a short time, when it will be observed
to be bleached uniformly white (the longer the negative is bleached the
denser it will ultimately become). Remove from the bleaching solution,
wash in running water for a few minutes, then blacken in the following
solution :
Sodium Sulphite 1 ounce (30 grammes)
Water 4 ounces (120 grammes)
Or
Ammonia 20 minims (1 c.c.)
Water 1 ounce
* "Electro-Therapeutics and Roentgen Rays," Kassaban.
^2
ELEMENTARY RADIOGRAPHY
When sufficiently blackened, the negative is again washed, then dried.
Intensifying should be done in a subdued light — not in bright daylight.
An old negative, one which has been made for some time, may be
intensified by first soaking in water, then following the technic given.
Prepared reducers and intensifiers, with directions for their use, may
be purchased at any photographic supply house.
Fig. 77. Showing how the printing frame is held up to the light to expose the photographic
paper. Also showing the back of the printing frame, the frame half open, and the photographic
paper in position.
While reducers and intensifiers have their place in dental radiog-
raphy, they are used only to correct mistakes, and they do not entirely
correct the mistakes. It is usually expedient to make a new negative
rather than to attempt to reduce or intensify a faulty one.
Round transparent spots on the negative are caused by air bubbles,
or air "bells," as they are called, attaching themselves to the emulsion
side of the plate while in the developer.
Spots of irregular size and character appearing on a negative are
due often to the use of an old developer. In radiographic work, where
the appearance of a spot may determine a diagnosis, it is to be hoped that
fresh developer will always be used. By fresh developer I mean de-
veloper not, at most, over a month or so old, having been kept while in
stock in a filled, tightly stoppered bottle, and free from all scum and
sediment. A developer containing pyrogallic acid disintegrates so rap-
idly that it must be used immediately after mixing — it will not keep at
all. "Pyro" developers stain the hands badly.
MAKING RADIOGRAPHS 83
When the negative is dry we are ready to make
Position the positive pictures. The pictures are made on
Prlnt$, sensitized paper, a very fine grade of white paper,
one side of which is coated with a silver salt some-
what as plates and films are coated. These papers sell under such vari-
ous names as Velox, Cyko, Artura, and Azo, and may be purchased in
any size, put up in light-proof packages. Papers are not as sensitive as
plates and films, and an orange instead of a ruby light may be used in
the dark room.
Place the negative, emulsion side up, in the printing frame (Fig. yy).
Place a sheet of paper, sensitive side down, over the negative, and close
printing frame. The sensitive side of the paper may be determined by
observing that the paper curls slightly toward it ; or by biting a corner
of the paper, when the sensitive side will stick slightly to the teeth.
To make the exposure now, either artificial or daylight may be util-
ized. Before making the exposure be sure that the balance of the paper
in the package is well protected against the light. Hold the printing frame
so the light will shine through the negative and strike the paper. (Fig.
yy.) It is not necessary to hold the printing frame immovable during
exposure. The time of exposure varies greatly according to the density
of the negative ; the denser the negative the longer the exposure must be.
Some idea of the time of exposure necessary may be learned from the
directions enclosed with the paper. To make the print for Fig. yi, a
16 c.p. electric light was used holding the printing frame about 8 inches
from the light and exposing the paper — Azo — 3 minutes.
With the 16 c.p. light turned off, in the orange
Development light, the paper is now removed from the frame. As
Of Prints. with the plate there is not the slightest change in the
appearance of the paper after exposure, but the
image is there, it is latent, it needs only to be developed.
The developing formulae for papers are, broadly speaking, the same
as for plates. It is very important that the developer for paper be freshly
mixed, for the slightest discoloration of the bath will soil the paper. It
is not desirable to save the developer used to make the negative and use
it again for the paper. It is too liable to cause discoloration of the print.
"Pyro" is a very poor developer for paper.
Immerse the paper quickly, sensitive side up, gently passing the tips
of the fingers over the surface, to hasten development by agitating the
developer, and to keep the paper submerged. As soon as the image ap-
pears as desired, transfer it to clean water, then quickly into the fixer.
(It is kept in the water but a moment or so.) If, when placed in the
developer, the image comes up so quickly that it gets too dark before it
84 ELEMENTARY RADIOGRAPHY
can be transferred to water and fixer, it has probably been overexposed.
Shorten the time of exposure, and if the image still comes up too quickly,
dilute the developer. If the image appears very slowly and the whites
of the print are gray, increase the time of exposure ; if the whites still
come gray, add a few drops of a lo per cent, solution of bromide of potas-
sium to the developer. >^
The fixing bath for prints is the same as for plates, but the oath
used to make the negative should not be saved and used again for prints.
It might discolor them.
Allow prints to remain in the fixer 15 to 20 minutes. This dissolves
out the unaffected silver.
Next wash print in running water for about thirty minutes. No visible
change occurs in the print from the time it leaves the developer. Fixing
and washing are done to make it permanent. The temperature of the de-
veloper, fixer, and water should be the same as for plates, to obtain the
best results.
When thoroughly washed remove the prints from the wash water
and place on a piece of clean glass face down one on the other, and
press out the water. Then lay them out separately on a frame, covered
with cheese cloth. The cheese cloth being very thin, allows the prints
to dry on the side next the cloth as well as the upper side.
When dry the prints may be mounted on cardboard.
Dental Radiography or Radioaontio.*
CHAPTER V.
makiiid Dental Kaaiograpbs.
In the foregoing chapter we dealt with the general elementary prin-
ciples of radiography. We shall now take up a more concrete considera-
tion of dental radiography.
The first radiograph of the teeth was exhibited by Prof. Koenig to
the Society of Physics at Frankfort-on-Main, Germany, in February,
1896 — only a few months after the discovery of the X-ray. Five months
later an article appeared in Dental Cosmos by Morton, entitled " X-rays
in Dentistry." Since then there have been many articles written on the
subject and published in various dental, medical, and Roentgenographic
journals.
For convenience in describing the technic involved in the practice of
dental radiography the subject will be considered under the following
heads : ( i ) Manipulation of the X-ray machine and lighting of the X-ray
tube. (2) Posing the patient and adjusting the X-ray tube and film or
plate. (3) Exposure. (4) Making the negative.
Cbe manipulation of tbe X-Ray niacbinc and Cidbting of tbe
X-Ray CuDc.
Since the X-ray machine of each manufacturer has characteristics of
control peculiar to itself I can give here only the general principle of
manipulation.
As the reader already knows, there are three types of X-ray machines
in general use: (i) The induction coil. (2) The high-frequency coil.
* Radiodontia is a new word coined by the writer. Radiodontia is the science
and art of making and interpreting radiographs of the teeth and contiguous parts.
A radiodontist is one engaged in the practice of radiodontia.
These words will be found quite useful and have been promptly adopted by
all interested in the subject except advocates of Roentgen words, who believe all
X-ray words should contain the proper name Roentgen, no difference how un-
wieldy or senseless they may be.
85
86
DENTAL RADIOGRAPHY
(3) The transformer. We shall consider the manipulation of the induc-
tion coil first.
Different induction coils have a different number
«Jl?T«'J.!!l5!lSVLi of controls of various sorts. Selecting a coil with
all the different controls I shall name them, (bee
MAIN SPARK TERMINAL
MILL I AMMETER
VACCUM REDUCINQ LEVER
SERIES SPARK QAP
AMMETER
VARIABLE INDUCTANCE
SWITCH
RHEOSTAT LEVER
RESISTANCE ALL IN
RESISTANCE ALL OUT-xf:
SWITCH LEVERS TO
PLATINUM POINTS
Fig. 78. Induction coil, showing the various controls.
Fig. 78.) First, the "on and off switch"; second, the "pole changer";
third, " the rheostat lever " ; fourth, interrupter switches, levers and
screws " to platinum points " ; fifth, the parallel or " main spark " gap ;
MAKING DENTAL RADIOGRAPHS 87
sixth, the " vacuum reducing lever " ; seventh, the " series spark gap " or
inverse current spark gap ; eighth, the " variable inductance switch."
The " on and off switch " is the one by means of which the current is
turned into the machine. This control is on all coils.
The "pole changer" (Fig. 78) is a double-throw knife switch by
means of which the secondary current, or output current produced by the
coil, can be made to flow in either direction — when this switch is down
on one side the current flows in one direction, when it is down, or closed,
on the other side it flows in the opposite direction. If, after the tube is
connected to the coil, it is found, by the manner in which the tube lights,
that the current is traveling through it in the wrong direction (Fig. 48 and
bottom of page 52) the tube need not be detached and re-attached to the
coil ; instead, change the pole changer switch. This pole changer control
is found on comparatively few induction coils.
The rheostat controls the quantity of electricity entering the machine
and so the quantity produced by the machine to be sent through the tube.
(Fig. 30.) On very large induction coils it is often inexpedient to cut out
all of the resistance of the rheostat, while on the smaller ones, and the
special dental X-ray coils of the induction coil type, it is usually necessary.
Always, when the current is turned into the tube for the first time, the
rheostat lever should be on a low button. The rheostat control is found
on all induction coils.
Multiple point electrolytic interrupters are equipped with switches by
means of the manipulation of which only one, only a part, or all of the
platinum points may be used. Screws or levers, or both, control the length
of the platinum exposed in the electrolyte. For the beginner at least it
is best that the interrupter adjustment be made or set and its further
manipulation avoided as much as possible. If more than three points are
used in the interrupter, set the platinum exposed to the electrolyte at from
y% to 2/8 inches. If one to three points only are used, set the exposure
of the platinum to the electrolyte between 2/8 and 3/8 inches.
Interrupters are made which adjust themselves automatically. The
end of the platinum rests against a piece of porcelain. It is weighted
down to place, and thus the amount of platinum exposed remains the same
always. In this style of interrupter base metal is sometimes used instead
of platinum. The exposed metal disintegrates and wears away but the
weight keeps the end of the point resting against the porcelain and so
the amount of the point exposed remains the same. (Fig. 79.)
The parallel spark gap may be manipulated to determine the number
of inches of spark the tube will back up and so determine the degree of
vacuum. (Pages 42 and 43.) As the operator becomes familiar with his
88 DENTAL RADIOGRAPHY
tubes and machine he will manipulate this gap less. It is the practice of
some men to set this gap at about 7 inches and leave it there, resorting to
the regulation of the vacuum of the tube only when sparking occurs at the
parallel spark gap. The parallel spark gap control is found on all induc-
tion coils.
The '"' vacuum reducing lever " is the lever by means of which the
tube-regulating spark gap (Pages 46 and 47) is made wide or narrow.
If the tube will light properly, and no sparking occurs at a 6 to 8-inch
parallel spark gap, the tube requires no vacuum regulation. If sparking
occurs across 6 to 8 inches of parallel spark, reduce the distance of the
xfe^^r:^
Fig. TU. Self-adjusting electrolytic interrupter.
tube-regulating spark gap to an inch or two and, with the rheostat on a
low button, turn on the current for 2 or 3 seconds. This may be repeated
if necessary and will lower the vacuum of the tube. As tubes get old,
the vacuum gets high, and they become "cranky." To handle an old
tube it is often necessary to open the parallel spark gap as wide as pos-
sible, and set the tube-regulating spark — 5 inches for a slightly " cranky "
tube, as short as 2 inches for a very high " cranky " tube — allowing the
MAKING DENTAL RADIOGRAPHS 89
tube- regulating spark gap to remain set all the time the current is turned
on. The object of the operator should be to avoid regulation of the
vacuum of the tube as much as possible.
The " vacuum reducing lever " control is not found on all induction
coils. When the machine does not afford this control, the width of the
tube-regulating spark gap is controlled by means of a movable arm at
the tube. (Fig. 44.)
The " series spark gap " or inverse spark gap, should be used only
when necessary to cut inverse current out of the tube, otherwise the gap
should be closed. If a valve tube (Figs. 51 and 52) is used it is seldom
necessary to make a series spark gap.
By means of the " variable inductance switch " the output current of
the induction coil can be raised or lowered in voltage. The voltage re-
quired for a new tube is not as great as the voltage required for an old
tube with a higher vacuum. When a great deal of inverse current is seen
in a tube it may mean that the induction coil is generating a current too
high in voltage. When a new, unknown tube is used for the first time on
an induction coil with an inductance switch, start with the lowest voltage,
and the rheostat on a low button. Flash the current through the tube,
advance the rheostat, flash again and so on until all of the resistance of
the rheostat is cut out. If no inverse current has been observed in the
tube, advance the inductance switch to a higher voltage, start with the
rheostat on a low button again, flash the current as before and so on, ad-
vancing to a higher voltage in this way, until the tube shows inverse cur-
rent passing through it. The tube should be operated just this side of the
point where inverse current appeared in it — say for example on inductance
button 3, rheostat button 15. If the tube is labelled, inductance 3, rheostat 1 5,
it may be used with the machine set according to the label for some time.
Comparatively few induction coils have the " variable inductance " control.
Summary of Cccbnfc The technic for lighting an X-ray tube with an
tube Wltb TndUCtlon induction coil (without a variable inductance con-
Coil. trol) may be summarized as follows: (i) Test the
coil by means of the on and off switch, starting with the rheostat on a low
button and advancing the rheostat between test flashes. You should be
able to obtain at least 5 or 6 inches of fat, fuzzy, parallel spark. This step
is unnecessary save for the beginner using a new coil for the first few
times. It shows such a beginner how much of the resistance of the rheo-
stat must be cut out to obtain a fat, fuzzy spark. It shows that the
machine Is operating properly, that the interrupter is properly set. On
some machines with terminals of the right shape it enables the operator
to determine the polarity of the parallel spark gap terminals. (Page 42,
90
DENTAL RADIOGRAPHY
Fig. 40.) (2) Connect the tube to the coil. (3) Set the parallel spark
gap at about 6 or 8 inches.* (4) With the rheostat on a low button flash
the current on. Advance the rheostat between flashes. If the current is
passing through the tube in the wrong direction change the pole changer
switch or reverse the attachment of the tube to the coil. Once the polarity
of the terminals has been determined the operator may depend on this
polarity remaining the same, unless the pole changer switch is changed,
and he may always connect the tube to the coil accordingly. // sparking
occurs at the parallel spark gap, lower the vacuum of the tube. // in-
verse current is seen in the tube, make a series spark gap or place the
rheostat lever on a lower button, A little inverse current in a tube will
not materially interfere with the making of a good radiograph, especially
if a diaphragm and cone or cylinder are used. (Fig. 65.) The great dif-
Fig. SO. Drawing of a high-frequency X-ray machine showing various controls.
ficulty in the technic of operating an induction coil is the problem of not
allowing inverse current to pass through the tube.
The controls shown in Fig. 80, for a high-fre-
l)i9b-f Kqucncy eon. ^^^^^y ^^^^ ^^^- ^^'"^t' ^^^^ frequency control,
labelled " high-frequency " and " X-ray " ; second,
the on and oH switch, labelled " switch " ; third, the " rheostat " ; fourth,
the " regulating spark gap " ; fifth, the " terminal spark gap " or parallel
spark gap.
By means of the "high-frequency" and "X-ray" control switch
either all or part of the condenser of the machine is used. When on the
" X-ray " button all of the condenser is used and the frequency is lower.
This button is sometimes labelled " low frequency " instead of " X-ray."
* See page 349 for Soft Tvibe Technic.
MAKING DENTAL RADIOGRAPHS 91
This control is found only on machines built for electro-therapeutic work
as well as X-ray worK.
The on and off " switch " turns the electricity into the machine.
The " rheostat " controls the quantity of electricity entering machine.
The " regulating spark gap " controls, within limits, the nature of
the output current delivered by the machine. Widening the gap increases
voltage at the expense of milliamperage, narrowing it increases milli-
amperage at the expense of the voltage. The gap should be as narrow as
possible with the voltage high enough to jump the maximum parallel spark
gap. (As the machines of this type are now built, the maximum spark
gap is usually about 6 inches.) This gives the greatest milliamperage
obtainable with sufficient voltage, or pressure, to force the current through
a medium or medium-high vacuum, X-ray tube. The metal studs at the
" regulating spark gap " should be cleaned occasionally : Place a piece
of emery cloth or sandpaper between the studs, screw them together until
they hold the cloth or paper loosely, and draw the cloth or paper back and
forth over the surface of the stud.
On machines of this type, the parallel spark gap is practically always
kept at its maximum width for X-ray work. If sparking occurs across it
the vacuum of the tube must be lowered. When the tube is old and the
vacuum of the tube cannot be lowered sufficiently to stop sparking be-
tween the terminals (remember the terminals are only about 6 inches
apart on this type of machine) the writer has resorted to placing a piece
'\f glass between them. This is a strain on the insulation of the coil.
Suminary pf tcchnic The technic for lighting an X-ray tube with a
f or Cigbting X-Kay iir 1 1 , rn
Cube wUb Rigb= high-trequency coil may be summarized as follows :
Trcaueitcy Coil. (i) open the parallel spark gap to its maximum
width, i.e. 6 or 7 inches. (2) Cut out all resistance of the rheostat.
(3) Turn on the on and off switch and adjust regulating spark gap to get
as fuzzy a spark as possible. (This should be done as quickly as possible
so the current, with all of the resistance of the rheostat cut out, will not
be turned into the coil needlessly long.) (4) Turn current off and con-
nect tube to coil. (Since the current produced by this machine is alternat-
ing either terminal may be attached to the anode end of the tube.)
(5) With the rheostat on a low button, flash the current through the tube.
Advance rheostat, flash again, advance rheostat and so on until all the
resistance of the rheostat is cut out. (6) If sparking occurs at the parallel
spark gap, reduce the vacuum. The most convenient way to do this on a
machine not equipped with a vacuum reducing lever, where the vacuum
is controlled by a movable arm at the tube (Fig. 44), is to set the arm to
give a certain width to tube-regulating spark gap and leave it there. For
92
DENTAL RADIOGRAPHY
new tubes the tube-regulating spark gap should be 5 or 6 inches, for old
tubes 2 or 3 inches, this to be governed by sparking at the parallel spark
gap. If sparking occurs at the parallel spark gap the width of the tube-
regulating spark gap should be reduced until this ceases.
In case the high-frequency coil is operating on a direct current circuit
MILUJ flMMETEl^
TUBE TERMINBI.S
RUNNINq
POSITION
END View
Fig. 81. Drawing of a transformer or interrupterless X-ray machine showing various controls.
the first step in the technic of manipulating the coil is to set the rotary
converter in motion. This is accomplished by means of a switch and
rheostat. (Fig. 37.)
_ . „ _ The controls on a transformer built for an A.C
manipulation of JJ. C. . ., i^- ^ /it- o n ^t, » ^u»
translormm. circuit are: First (Fig. 81), the mam switch ;
second, the synchronous motor switch, a two-pole,
double throw, knife switch labelled " starting switch " in Fig. 81 ; third,
MAKING DENTAL RADIOGRAPHS 93
the " on and off switch " which controls the output current of the ma-
chine; fourth, the "pole changer switch"; fifth, the "rheostat" which
controls the quantity of output current; sixth, the "vacuum reducing"
lever.
The " main switch " simply brings the current up to the machine.
By means of the " starting switch " the motor is set in motion. This
revolves the " rectifier switch." The switch is thrown one way to start
the motor, then, quickly while the motor is in motion, to the other side.
When the " on and off switch " is closed, the current is sent into the
primary of the transformer and immediately the secondary current, or
output current of the coil, jumps the parallel spark gap, or, if an X-ray
tube is connected, passes through it, providing, of course, the vacuum of
the tube is not too high.
The "pole changer" double throw switch, works on exactly the same
principle as the pole changing switch on an induction coil. Unless the
A.C. transformer is equipped with an indicator one never knows, before
testing the current through the tube, which is the positive and which the
negative terminal. Which way the current will flow depends on how the
rectifying switch happens to pick it up. Some machines do not use the
" on and off switch " shown in Fig. 81, but eliminate it entirely, and use
the double-throw pole changer switch, trying it first on one side, then on
the other, if necessary, to send the current through the tube in the right
direction.
The " rheostat " controls the amount of current entering the primary
winding of the transformer and so controls the strength of the output
current.
The lever, or sliding rod, for reducing the vacuum on a transformer
is practically the same as the lever, or sliding rod, for the same purpose
on an induction coil. (Figs. 78 and 45.)
Summary of CechniC The technic for lighting an X-ray tube with an
Cub{ With H C. ^■^' transformer may be summarized as follows :
transformer. (i) Connect the X-ray tube to the coil. Either ter-
minal may be attached to the anode. (2) Have the parallel spark gap
about 6 or 7 inches wide.* (3) With the rheostat on button i flash the
current through the tube. (4) If the current is not passing through the
tube in the right direction reverse the pole changer switch. (5) Advance
the rheostat, with intermittent flashes, until the desired amount of current
passes through the tube. According to the machine used and to the length
of time the operator wishes to give for exposure, the current sent through
the tube may be anywhere from 10 to 20 milliamperes to as much as 40
or 50 milliamperes. (Practically all machines of this type are equipped
* See page 349 for Soft Tube Technic.
94 DENTAL RADIOGRAPHY
with milliammeters.) If the machine used is a very smaU one (one of
the special dental machines) all of the resistance of the rheostat is usually
cut out, if the machine is a large one, from a half to three-fourths of the
resistance of the rheostat is cut out.
If, when the current is first flashed through the tube, some sparking
occurs at the parallel spark gap, lower the vacuum of the tube by reducing
the tube regulating spark gap to an inch or so and, i^ifh the rheostat on a
very loiv button, turn the current on for about 2 or 3 seconds. If the
rheostat is advanced too far when the vacuum of the tube is lowered, too
much current will pass through the regulating chamber and the vacuum
of the tube will be made too low. Transformer tubes require rery little
vacuum regulation and the less done the longer the tube will give good
service.
When lighting a tube with a transformer no manipulation is neces-
sary to eliminate inverse current from the tube, for the machine produces
no inverse current. This simplifies the manipulation for tube lighting
tremendously.
Summary of CccbniC The technic for lighting an X-ray tube with a
^^CubC^wUb DC ^-C transformer is so much like the operation of an
transformer. A.C. transformer that a summary of it would be sim-
ply a repetition of technic already given. There are, however, two points
of diiTerence to which I direct your attention.
The first step in operating a D.C. transformer is to start a rotary con-
verter and this is done by means of a switch and rheostat.
Because the current from the rotary converter, and not the line cur-
rent, enters the primary of the transformer in a D.C. transformer, polarity
of the terminals always remains the same, unless the pole changing switch
is changed. Thus it is not necessary to test the current through the tube
or observe an indicator each time to learn which way the current is flowing
when using a D.C. transformer as it is when using an A.C. transformer.
Once the operator learns which terminal is positive he may depend on it
this terminal will remain positive always, unless the pole changing switch
is changed and he mav connect his tube to the coil accordinsrlv.
Posing m Patient and JIdjusting the X=Rav CuDe and Tilm or Plate.
Dental radiographs, or odontoradiographs, have been divided into two
classes: (i) The intra-oral and (2) the extra-oral. Intra-oral radio-
graphs are made by holding films in the mouth ; extra-oral radiographs
are made on plates, or films, usually plates, placed outside of the mouth
for exposure.
MAKING DENTAL RADIOGRAPHS
95
Tntra-Oral
Kadiosrapbs
It makes no difference what sort of a radiograph
is to be made, it should always be borne in mind,
while posing the patient and adjusting the tube and
plate, or film^ that you are using your X-rays as a source of light to cast a
shadow of some object — i.e., the object being radiographed — on a screen —
i.e., the film or plate.
To impress this idea more firmly in your mind observe Fig. 82. The
source of light, the candle, casts a distorted — an elongated — shadow of
Fig. 82.
the object, a plaster of Paris tooth, on a white screen. As you observe this
illustration contemplate what would have to be done to overcome the ex-
treme distortion of the shadow and make it approximately the same length
as the tooth. Is it not true that either the light must be moved upward or
the screen must be placed more nearly parallel with the tooth, or perhaps
a little of both? If you follow this reasoning you are on the way to mak-
ing proper poses for radiographs, for the principle involved is the same.
The ideal pose for making a radiograph is to have the focal ray, or
central ray, indicated by the pointer at the end of the cylinder in Fig. 83,
directed to strike the object being radiographed, and the plate or film,
96
DENTAL RADIOGRAPHY
at right angles. (See Fig. 70.) This is impossible much of the time in
the practice of radiodontia.
Distance Between ^^ ^^^ beginner first attempts posing patient and
X-Ray Cube and adjusting his tube his first question is, " How close
Patient. should I place the tube to the patient? " If the tube
stand used is one with a cone or cylinder, the length of the cone or cylinder
will govern this. The cone or cylinder will almost touch the patient.
If a shield like the one shown in Fig. 64 is used let the distance between
the glass of the tube and the patient's face be an}^vhere from 6 to about
12 inches.
Fig. 83.
Proper posing can be taught best by observation of illustrations, but
before proceeding further with the subject of posing we should stop and
consider the films used for dental X-ray work.
Dental X-Kay
Tilms.
The Eastman Kodak Co. supplies films espe-
cially prepared for intra-oral dental X-ray work, in
three sizes: No. i film 1% by i^ inches, No. lA
film i^ by 2%. inches and No. 2 film 2^ by 3 inches. These films are
supplied in packets, two films to a packet, wrapped in black paper to pro-
tect them from ordinary light, over which is wrapped oil paper to protect
them against moisture when placed in the mouth. The most populai size
is the No. i.*
*A new size film, 1^ by 2 inches, suggested by the writer for the posterior
teeth, has just been placed on the market.
MAKING DENTAL RADIOGRAPHS 97
There are two kinds of Eastman X-ray films : " Positive " films and
" negative " films. The names " positive " and " negative " are mislead-
ing. They give one the idea that there is some difference in the films
without suggesting at all what the difference is. The differences between
the " positive " and " negative " Eastman X-ray films are : The " posi-
tive " is less sensitive than the " negative " film ; it therefore requires a
longer exposure than the " negative " film and need not be handled with
the same care in the dark room. Radiographs made on the " positive "
film are more " contrasty " than those made on the " negative " film.
It is a matter of interest to know how the names " positive " and
" negative " happen to be applied to the Eastman films. The first films
supplied to the dental profession for X-ray purposes by the Eastman Co,
were cinematograph — i.e., motion picture films — cut to the proper size and
covered with black paper. There are two kinds of cinematograph films,
the negative and the positive. The negative is the one used in the motion
picture cameras to obtain the original negatives of the scenes and action
Fig. 84. A, rubber dain stretched out and fastened to a board with pins. B, the rubber covered
with cement and the iilm packet on it. C, pins removed from one end and the rubber lapped
over packet. D, all pins removed. E, excess rubber trimmed oft'.
pictured. The positive film is the one used to make the " reels " used in
the projection lanterns at the motion picture theaters. The " reels " made
on the positive film, for the projection lanterns are made from the original
negative made on the negative film. It is not unlikely that the words
pocitive and negative will soon be displaced by the words slow and fast :
The positive films will La known as the slow films, the negative as the
fast films.
Besides the films prepared especially for dental X-ray purposes, the
Eastman Co. also makes films of all standard sizes — i.e., 4 by 5 inches,
5 by 7 inches, 6^-^ by 8^ inches — put up in light-proof packages of i or 2
doz. films.
If he desires to do so the operator may, in his dark room, cut these
larger films to any desired size or shape and cover them with black paper
himself. For protection againct moisture he may cover the black paper
with rubber dam — Fig. 84. Or he may take a piece of mending tissue,
such as is used by tailors to mend clothing, of such size that when folded
over the film packet (Fig. 84C and D) it will extend beyond the packet
98 DENTAL RADIOGRAPHY
on the three open sides, about one-half inch. Warm the edges of the
tissue slightly by passing it over the flame of an alcohol lamp, or Bunsen
burner, and pinch them together. Then warm them (the edges) to stick-
iness again and turn them back and stick them to the tissue covering the
back — i.e., the non-sensitive side — of the film packet.
There is no particular advantage derived from preparing one's own
film packet, and the practice is rapidly being discontinued. When the
X-ray machine used is small and the time of exposure is long, it may be
found expedient sometimes to give more protection against moisture than
is afiforded by the oil paper of the prepared film packet.
For the time being, owing to the war in Europe, the Eastman is the
only available X-ray film so far as I am able to learn. The Ilford and the
S.chleussner are X-ray films manufactured abroad.
Fig. 85. Position of film in mouth for making radiographs of the upper cuspid, bicuspid and first
molar region.
The smooth side of the Eastman film packet, the opposite side to the
one on which the ends of the covering paper lap, represents the sensitive
side of the enclosed films. When placing the film packet in the mouth
have the sensitive side of the films — i.e., the smooth side of the packet —
present toward the teeth. Except when intensifying screens are used (see
index: intensifying screen) the sensitive side of films and plates always
present toward the object to be radiographed and the X-ray tube.
With the film placed In the mouth as per Fig. 85
Posterior tectb. *^ P°^^ should be as in Fig. 86. Figure 87 is a dia-
grammatic illustration of the pose shown in Fig. 86.
With the film placed in the mouth as per Fig. 85, Fig. 88 represents
an incorrect pose. The angle at which the X-rays are directed at the
MAKING DENTAL RADIOGRAPHS
Fig. 86. The correct pose for making ra.liouraplis (if th • upper bicuspid and molar region and
a radiograph made from the pose.
Fig. 87. Diagrammatic illustration of pose seen in Fig. 86, showing the X-rays striking the tooth
and film at such an angle as to avoid either lengthening or shortening of the shadow cast
on the film. (Schematic drawirg after Dr. Price)
100
DENTAL RADIOGRAPHY
Fig.
Incorrect pose for radiographing the upper bicuspids and molars, and a radiograph
made from the pose.
Fig. 89. Diagrammatic illustration of the pose seen in Fig. 88, showing the X-rays striking the
tooth and film at such an angle as to cause elongation of the shadow cast on the film.
MAKING DENTAL RADIOGRAPHS
lOI
#^-
Fie
90. Incorrect pose for radiographing upper bicuspids and molars, snd a radiograph made
from the pose.
f/LM
Fig. 91. Diagrammatic illustration of the pose seen in Fig. 90, showing the X-rays striking the
tooth and film at such an angle as to cause shortening of the shadow cast on the film.
I02
DENTAL RADIOGRAPHY
teeth and film is not right. This position of the tube would be correct, if
the film were parallel with the teeth ; but it is impossible to place the film
in this relation to the upper teeth. Fig. 89 is a diagrammatic illustration
of the pose shown in Fig. 88.
With the film placed in the mouth as per Fig. 85, Fig. 90 illustrates
another incorrect pose. The X-rays do not strike the teeth and film at
the correct angle and the teeth in the resulting radiograph are too short.
Fig. 91 is a diagrammatic illustration of the pose shown in Fig. 90.
A study of Figs. 87, 89 and 91 will show that in order to make a
radiograph which will not picture the teeth too long nor too short the
♦•m»
Film
Fig. 92.
X-rays should strike the film almost, but not quite, at right angles to its
surface. This same idea has been expressed thus : " The X-rays should
be directed at right angles to a neutral line drawn between the film and
the tooth." Another writer expresses the same idea so : " Bisect the
angle made by the plane of the teeth, and the plane of the film, and direct
the rays so they will fall perpendicularly to this bisecting plane."
The angle of the film in Figs. 87, 89 and 91 is what it would be in the
average mouth. Suppose, however, the vault is very flat. In such an
event the angle of the X-rays as illustrated in Fig. 87 to be correct, would
cause a marked lengthening of the shadow, as illustrated by the dotted
lines and drawing in Fig. 92. The angle of the X-rays should°be as in
Fig. 91 to avoid, as nearly as possible, any distortion. (Notice in Fig. 92
that the bending of the film would cause a lengtbening of the shadow.)
MAKING DENTAL RADIOGRAPHS
103
Just in proportion as the vault becomes more flat the film departs
from the vertical and the tube must be at a different and higher angle.
And so, inversely, as the vault is higher the film may be placed more
nearly parallel with the teeth and the tube may be lowered.
From the foregoing it will be understood why we can never be sure
that our radiograph gives the exact length of upper teeth.
By making slight changes in the positions of the film as illustrated
Fig. 9o. Position of film in the mouth for radiographing upper anterior teeth. See pose Fig. 94.
in Fig. 85 and the tube as illustrated in Fig. 86, all of the teeth from the
third molars forward to the cuspids (and in some mouths the laterals)
can be radiographed.
Figure g-? illustrates the position of the film for
Pose for the Uvdci* ^ ■ ^■ ^ r ^
TInterior teeth niakmg radiographs of the upper anterior teeth.
While bending of the films is to be avoided as far
as possible, because it causes distortion of the radiographic image, when
I04
DENTAL RADIOGRAPHY
Fig. 94. Correct pose for radiographing upper aiiteriur tueth with film in the mouth as in Fig.
93. Radiograph made from this pose. (It tooli the writer a long time to learn that, when
radiographing upper anterior teeth, it is best to try to radiograph only two teeth at a time,
to bend a part of the film deliberately in order to avoid bending all of it (Fig. 101) and to
have the patient hold it with the thumb, not the fingers or finger.)
MAKING DENTAL RADIOGRAPHS 105
the film is placed in this position it is sometimes unavoidable, especially
in a mouth with a V-shaped dental arch. A small ball of cotton under the
film, in the palate, will sometimes assist in preventing too much bending,
without at the same time holding the film too far away from the teeth.
With the film placed in the mouth as in Fig. 93, the pose for making
radiographs of the upper anterior teeth is illustrated in Fig. 94.
Another position for the film when making radiographs of the upper
teeth is illustrated in Fig. 95. The sensitive side of the film presents
toward the teeth. The film is held in position by having the patient close
the mouth. Fig. 96 illustrates the pose with the film in the position shown
Fig. 95. Position of the film in the mouth for pose and radiograph seen in Fig. 96.
in Fig. 95. A radiograph made in this way is liable to considerable dis-
tortion. The radiograph in Fig. 96 was made when radiographers pre-
pared their own film packets, cutting a film of the desired size from a
large film and wrapping it in black paper. I quote from the first edition
of this book : " After making a radiograph as shown in Fig. 96, it may
be trimmed to a more symmetrical form. In other words, the film, as
wrapped tip in a film packet may be left an indefinite, unsymmetrical
form and trimmed to a more pleasing outline after the radiograph is
made.'*
With the film placed in the mouth as shown in
^To$tIr[ort«tbT'' ■^'^- ^^' ^^^ correct pose for making radiographs of
the lower molar region is illustrated in Fig. 98.
Note that the rays are directed at the teeth and film at right angles. If
the radiograph resulting from this pose does not show the apices of the
io6
DENTAL RADIOGRAPHY
Fig. 9G. The pose with the film in the mouth as in Fig. 95 and the radiograph made from this
pose.
teeth, press the fihii down farther if possible. If this cannot be done the
tube must be tipped, slanting the rays upward, something like the rays are
slanted downward for the upper teeth, or the head may be tipped side-
ways from the tube which accomplishes the same thing.
With the film placed in the mouth as shown in Fig. 99 the pose for
making radiographs of the lower cuspids and bicuspids is illustrated in
Fig. 100. Note that the rays are directed disto-XingnaMy and slightly up-
ward.
MAKING DENTAL RADIOGRAPHS 107
Figure loi shows the film packet placed in posi-
Poses for the Eower ^-^^ ^^^ radiographing the lower anterior teeth.
Note that about ten millimeters of the packet is bent
abruptly backward. This is done because the packet is too wide for the
dental arch and it is better to bend back a part of the film abruptly, and
so allow the film to go to place, than to bend the entire film in an effort
to get it into a space too narrow for it. A little cotton between the film
and inner surface of the dental arch sometimes helps in preventing undue
bending of the film.
Figure 102 is the correct pose for making radiographs of the lower
anterior teeth with the film in the mouth as per Fig. loi. Owing to the
Fig. 97. Position of the film in the mouth for radiographing the lower molars. See pose Fig. 9S-
difficulty in placing the film parallel with the teeth, without bending the
surface of the film too much, it is usually necessary to tip the head back-
ward and direct the rays upward and lingually in order to make the apices
of the roots show in the radiograph.
With the film placed in the mouth as shown in Fig. 95, except that
the sensitive side presents toward the lower teeth, a radiograph may be
made from the pose shown in Fig. 103. Such a radiograph is liable to
great distortion.
A study of Fig. 104 will assist the operator materially in directing the
rays through the parts at the proper angle. From this illustration one
can promptly see why the shadow of the mesiobuccal root of upper molars
is usually thrown to the mesial of the lingual root, while the shadow of
io8
DENTAL RADIOGRAPHY
Fig. 98. Pose for radiographing the lower molars with the film in the mouth as in Fig. 97.
Radiograph made from this poee. The film holder in use is illustrated in Figs. 331, 332
and 333.
the disto-buccal is superimposed on the lingual root. (Fig. 105.) The
shadow of the disto-buccal root can sometimes be thrown to the distal of
the lingual root by directing the X-rays through the part in a disto-\mg\.\?i\
direction.
When radiographing lower molars it is often necessary to direct the
rays through the part in a disto-\mg\id\ direction to obtain a clear outline
MAKING DENTAL RADIOGRAPHS
109
of the roots. This sometimes superimposes the two mesial canals one over
the other. Observe the roots of the second molar on the reader's left in
Fig. 104 and note that directing the rays straight through— i^., at right
angles to the long" axis of the tongue— would cast the mesio-buccal canal
on the film to the mesial of the mesio-hngual canal.
There are various methods of holding the film
in the mouth during its exposure to the X-rays. The
different poses, already illustrated, show the methods
metboas of 1)0lding
films in the nioutb.
Fig. 99.
Position of film in the mouth for radiographing lower cuspid and bicuspid region.
See pose Fig. 100.
now in use by the writer. For the upper teeth, the patient holds the film,
with the thumb usually. For the lower posterior teeth the film holder
illustrated in Fig. 333 is used. For the lower anterior teeth the patient
holds the film with the finger or with the Leach film holder. The set of
Leach film holders, designed by Dr. Floyd Leach of Chicago, illustrated
in Fig. 106, have been in the hands of the writer only a few days now —
no
DENTAL RADIOGRAPHY
Fig. 100. Pose for radiographing the lower cuspid and bicuspid region with the position of the
filin as in Fig. 99. Radiograph made from this pose. Tipping the tube is not necessary
and not advisable if the film can be placed down far enough.
an insufficient length of time to give them a fair trial. It may, neverthe-
less, be stated that the Leach film holders will be found very useful,
especially to the beginner.
Dr. Tousey, of New York City, and Dr. Ketcham, of Denver, have
also designed special dental film holders.
I am not inclined to consider the question of the operator or assistant
holding the film, further than to warn you against the practice. (See
MAKING DENTAL RADIOGRAPHS
111
chapter VIII.) Do not do it; the repeated exposure is dangerous. Have
the patient hold the film.
Some difficulty due tO' gagging is sometimes experienced when the
film is held in position for upper second and third molars. To patients
who will not tolerate the film in this location, I sometimes say this : " I
know you cannot keep from gagging when something tickles your palate.
But, did you know this? you can keep from gagging as long as you can
hold your breath/' Unless the X-ray machine used is a small one the
Fig. 101. Position of film for radiographing lower anterior teeth. See pose Fig. 102. The
principle, here illustrated, of deliberately bending a part of the film in order to avoid bend-
ing all of it, is, perhaps, the most important and fundamental single thing to be learned
about the application of films to the mouth. This principle is applicable not only to the
lower anterior region, but to other parts of the mouth as well, particularly the upper ante-
rior part._ To make the radiograph illustrated in Fig. 102 the film was bent abruptly back-
ward a little on both sides instead of on one side only as illustrated here.
exposure can be made while the patient " holds the breath." (The
psycho-therapist may analyze this treatment for gagging to his heart's
content.)
Plates are usually used in preference to films for
extra-oral radiographs because they are easier to
handle and cheaper. If the negative is to be sent
through the mail it is best to make it on a film. If films are used, two
films may be exposed simultaneously and so two negatives made from one
exposure. This is always an advantage in that if one film is not developed
extra-Oral
Radiographs.
112
DENTAL RADIOGRAPHY
Fig. 102. Pose for radiographing tlie lower anterior teeth with the position of the film as in
Fig. 101. Radiograph made from this pose. (Note the rubber matting covering the patient
where one of the terminals of the tube is brought close to the body. The rubber matting
acts as an insulation preventing sparking of the current into the patient.)
MAKING DENTAL RADIOGRAPHS
113
Fig. 103. Pose for radiographing the lower anterior teeth with the film flat against the occlusal
surfaces and incisal edges. Radiograph made from this pose. (Note rubber matting insula-
tion again.)
114
DENTAL RADIOGRAPHY
properly or becomes spotted or mutilated in some way the mistake or
accident may be corrected when the other film is developed. Also, if the
case is a referred one, one negative may be kept on file, and the other
Fig. 104. Horizontal section of the upper and lower jaws cut a little beyond the free margin
of the alveolar process, showing the forms and positions of the roots of the various teeth.
(From Cryer's "Internal Anatomy of the Face.")
sent to the dentist or physician who referred the patient. The Eastman
dental films, No. 3, 4 x 6 inches, and No. 4, 8 x 10 inches are prepared
in packets containing " a pair " of films, for extra-oral work.
A number of manufacturers supply special X-ray plates. (See chap-
MAKING DENTAL RADIOGRAPHS 115
ter IV, page 66.) The Brady product is particularly worthy of consid-
eration because, when it was first placed on the market it was the
" fastest " X-ray plate thus far made, and so it enabled men with small
X-ray machines to do extra-oral dental radiographic work, who had
hitherto found this work impossible, owing to the limited power of their
machines and the insufficient sensitivity of X-ray plates to the action of
the X-rays.
The size of the plate used for extra-oral work may be 4 x 5, 5 x 7,
65^ X 8^ or 8 X 10 inches. As the operator learns to pose his patient and
adjust his plate and tube with accuracy he will use a smaller plate. The
beginner had perhaps better start by using the 8 x lo-inch plate. The
size of the plate selected will, of course, depend primarily on the size of
the field the operator wishes to place under radiographic observation.
Fig. 105. Radiograph showing three roots of the upper first molar; the mesio-buccal root is to
the mesial, the disto-buccal root and the lingual root are superimposed one upon the other.
For the technic of handling the plate preparatory to making the radio-
graph see Chapter IV, pages 68, 69 and 70.
The best possible advice I can give the man who
Posterior Cecth contemplates doing any amount of extra-oral dental
radiographic work is that he obtain a skull and refer
to it often to assist him in posing his patient and adjusting the plate and
X-ray tube. He should also make many experimental, test radiographs
of the skull.
Extra-oral radiographs are made by having the patient lay the head
against the plate — which rests on a flat surface — and directing the rays
through the parts from above. (Figs. 107 and 108.) The side next to
the plate — i.e., the side farthest from the X-ray tube — is the one being
radiographed in such a position. The big problem in posing for radio-
graphs of this kind is to so arrange the plate, the patient's head and the
tube as to prevent superimposition of the two sides of the mouth.
ii6
DENTAL RADIOGRAPHY
Superimposition of parts may be avoided, to variable- extents, in three
ways. ( I ) By tipping the tube in such a way as to direct the rays through
the parts diagonally. (Fig. 107.) (2) By the use of an incline plane —
wooden pillow or wedge — 23 degrees. (Fig. 108.) (3) By directing the
patient, who will first naturally assume the position shown in Fig. 107,
to " turn the head until the nose touches, or almost touches, the plate."
(By having the patient turn the head farther, until the nose is flattened
to one side against the plate, satisfactory radiographs of the lower anterior
teeth may be made.)
Fig. lOG. Leach film holders. The holder in the middle is seen in use in Fig. 102.
The tube should not be tipped as in Fig. 107 when the incline plane
is used : When the incline plane is used direct the rays straight down-
ward.
Figure 109 is the radiograph made from the pose shown in Fig. 108.
As has been indicated in Figs. 107 and 108, extra-oral dental radio-
graphs may be made with the patient lying on a table or seated on a chair
or stool with the head placed on a stand or table. Figure no illustrates
a special tube stand attachment on which the head may be placed. Figure
MAKING DENTAL RADIOGRAPHS
117
no also illustrates a device for holding the head immovable. The writer
prefers the reclining position, however, when sufficient office space will
permit the use of a table.
While satisfactory radiographs of the lower
anterior teeth (see above) may be made on plates
placed extra-orally, sufficiently clear radiographs of
the upper teeth cannot be obtained by any means thus far devised, on
plates so placed.
Pose for tbc
^Interior tcctb.
Fig. 107.
Po$«$ for the Cranial
Sinuses and Cells.
There is such similarity in the symptoms caused
by dental lesions and those produced by diseases of
the cranial sinuses and cells that the radiodontist is
not infrequently called upon to make a differential diagnosis. The cranial
sinuses and cells are (i) the maxillary sinuses, or antra, (2) the frontal
sinuses, (3) the ethmoid cells, (4) the sphenoid cells and (5) the mastoid
cells.
With the patient's face placed against the sensitive side of the plate.
Fig. Ill illustrates a standard pose for making radiographs to give an
ii8
DENTAL RADIOGRAPHY
Fig. 108. Pose for making the radiograph seen in Fig. 109. The patient is Ivins on a table
^t^.°r',tl^nHi'l''H'T^l.^'?''i? holds apart the wires attached to the regulat ng Ihamber and
useful) ■ ^^""^ ^""P^^ ^'^^^ spreader" will often be found quite
MAKING DENTAL RADIOGRAPHS 119
Fig. 109. Radiograph made from pose illustrated in Fig. 108.
120
DENTAL RADIOGRAPHY
anteroposterior view of the frontal sinuses, the ethmoid cells and the
antra. (A better pose is illustrated and diagramed in Appendix Chap.
V.) Observe Figs. 112 and 113 made from this pose. (Figure iii
shows one end of a small chain attached to the metal of the tube-manipu-
lating apparatus. The other end of the chain is attached to a gas jet or
water pipe. This is called " grounding the current " to keep it from jump-
ing a small air gap into the patient. The tube is, of course, insulated
from the metal of the tube-manipulating apparatus and cylinder, but, be-
cause the electric current in use is of such high potential or pressure,
Fig. 110.
Tube stand with attachment for making extra-oral radiographs.
Eisen.)
(Photograph by Dr.
some current may, nevertheless, get into the metal parts, and from there
to the patient. With a small chain, or any electric conductor, attached
to the metal of the tube-manipulating apparatus and the other end at-
tached to a gas jet or water pipe the current will not jump an air gap
into the patient but will pass into the chain and through it to the gas or
water pipe, eventually reaching the earth possibly — hence the name
grounding. If the current jumps a small air gap into a patient a spark
occurs, due to the atmospheric resistance, and the sensation experienced
by the patient is very definitely unpleasant.)
Figure 114 is, in results obtained, the same as the pose illustrated in
MAKING DENTAL RADIOGRAPHS
121
Fig. III. In Fig. 114 an incline plane is used and the rays are directed
straight downward.
A studied observation of Fig. 112 will reveal to the reader a hori-
zontal shadow across the antra. If you will remove the skull cap from a
skull and look at the floor of the cranial cavity you will see that this
shadow represents the petrous portion of the temporal bone. The tube is
Fig. 111. Pose for making radiographs of the Antra of Highmore
tipped (Fig. 11 1) or an incline plane is used (Fig. 114) in order to throw
this shadow as far downward toward the teeth as possible.
_A straight-through lateral view of the antra may be made to locate
foreign bodies in it. (Figs. 277 and 278.)
Intra-oral radiography of the antra is not a success. (See Fig. 275.
Text on page 235 and 236.)
Figure 276 was made from a pose similar to Fig. 108. One antrum,
122
DENTAL RADIOGRAPHY
the one closer to the plate, is outlined with the dotted lines, the other
may be seen as the light area, to the reader's left and a little above the
outlined antrum.
Fig. 112. Radiograph made from the pose illustrated in Fig. 111. A, B, frontal sinuses.
C, D, orbits. E. F, ethmoid cells. F does not show as well as E because the cells of this
side are full of pus. G, H, Antra of Highmore, I, J, nasal cavity. As an aid in reading
the radiograph observe Fig. 113.
The sphenoid cells are situated back of, and a little below, the
ethmoid cells. Radiography of these cells is very difficult and in the hands
of most operators attended with little success. (See Appendix, Chap. V.)
For a consideration of the radiographv of the mastoids see Appendix,
Chap. V.
MAKING DENTAL RADIOGRAPHS
123
Exposure
When the patient and tube are properly posed, before' placing the
film or plate in position, flash the current through the tube once or twice
so that the patient may become acquainted with the light and noise pro-
Fig. 113. Same as Fig. 112.
A, frontal sinuses. _ B, orbits.
E. nasal cavity.
C. ethmoid cells. D, antra.
duced. Otherwise the patient might be startled when the current is first
sent through the tube, move, and so spoil the radiograph.
All films, plates and photographic paper should be kept in a lead.
X-ray-proof box, except just at the time of exposure. Fig. 115.
When making radiographs of the lower teeth with the film in the
124
DENTAL RADIOGRAPHY
mouth the patient should be warned not to swallow during the exposure.
Movement of the tongue in swallowing would move the film.
As stated in Chapter IV (see on page 71 ) a num-
titnc ot €XP0$UK. ber of things influence the time of exposure neces-
sary. For example, if the exposure necessary when
using the slow Eastman film is 4 seconds, all other factors may remain
the same, ^nd the exposure necessary for a fast Eastman film will be
only about i second.
Fig. 114. Pose for frontal sinuses, antra and ethmoid cells using incline plane.
Distance Between
target and film or
Plate.
The distance between the target of the tube and
the emulsion of the plate, or film, exerts a great in-
fluence on the time of exposure necessary. This
distance varies from about 10 to 20 inches. The time of exposure neces-
sary varies directly with the square of the distance. The square of 10 is
100, the square of 20 is 400. Thus the exposure at 20 inches should be
four times as long as at 10 inches. It has been suggested that the distance
between the target and the film be standardized at about 20 inches. This
is all right for men with large machines but the men who use the smaller
machines will find it expedient to have the distance less.
Age increases the density of osseous tissue and so the time of ex-
posure necessary to make dental radiographs varies slightly directly
according to the age of the patient.
The time of exposure for the molars, intra-orally is a little longer
than for the other teeth because the rays must penetrate the malar bone
for the upper molars, and the oblique ridges for the lower molars.
€x»0$U1*C Ulitl) tbe Since the type and size of X-ray machine used
Different types of governs the milliamperage sent through the X-ray
X-Ray lllacbines. tube, obviously this governs to a great extent the
time of exposure necessary. Taking into account the machines of all
MAKING DENTAL RADIOGRAPHS 125
sizes which are in general use the time of exposure necessary with IN-
DUCTION COILS, for intra-oral dental radiographs, varies from a frac-
tion of a second to about 15 or 20 seconds, for extra-oral dental radio-
graphs, from about i or 2 seconds to about 45 seconds ; with HIGH-
FREQUENCY COILS, for intra-oral dental radiographs, from about
3 to 30 seconds, for extra-oral dental radiographs, from about 12 seconds
to about I minute ; with TRANSFORMERS, for intra-oral dental radio-
graphs, from a fraction of a second to about 5 seconds, for extra-oral
dental radiographs, from a fraction of a second to about 10 seconds.
INDUCTION COILS, of various sizes operating at their full
capacity, are capable of forcing from 4 or 5 to about 18 + milliamperes
through a tube backing up 5 or 6 inches of parallel spark; HIGH-
Fig. 115. Lead-lined, X-ray-proof box for photographic supplies.
FREQUENCY COILS from about 3 to about 8 milliamperes ; TRANS-
FORMERS from about 12 to about 60 -)- milliamperes. (The plus mark
placed after milliamperage 18 for induction coils and 60 for transformers
is put there in recognition of exceptional X-ray machines of these types
which are capable of delivering a higher milliamperage. As I say, how-
ever, these largest machines are exceptional, i.e., not the type of machine
commonly met with.) Ordinary X-ray tubes, gas tubes, as they are called
since the advent of the new Coolidge tube, could not take a current of
60 milliamperes for much longer than about i second continuously with-
out injury to the tube from overheating.
When the time of exposure is over 5 seconds it is best to make the
exposure intermittently : turn the current on for 5 seconds then off for 5
seconds, then on for 5 seconds and so on until the desired time of exposure
126
DENTAL RADIOGRAPHY
is given. This avoids overheating the tube, and so lowering of the vacuum
by heating the regulating chamber.
When the time of exposure is i or 2 seconds, or less, an automatic
time-switch may be used to advantage. Fig. ii6.
X-ray tubes should not be used until they become so hot the hand can
not be placed on them. Heating takes place particularly in the region of
the cathode. If used until hot a tube should be allowed to cool before it
is used again. If much radiographic work is being done it is economy to
Fig. 116. Automatic time switch or " timer," ty means of which seconds may be split.
have at least three tubes. (The new Coolidge is an exception to this rule
as it is to almost all rules regarding X-ray tubes.)
With the milliamperage, the condition of the tube, and the emulsion
on the plate remaining the same, it requires an exposure about four times
as long for an extra-oral dental radiograph as for an intra-oral one. This
increase in the length of time necessary for the extra-oral dental radio-
graph is due to increased distance between the target and film, increased
thickness of tissue to be penetrated by the rays and increased distance
between the object being radiographed and the plate.
MAKING DENTAL RADIOGRAPHS 127
The exposure necessary for frontal sinus and antrum radiographs
with the pose as in Figs. 11 1 and 114, is longer than for radiographs of
any other part of the body. To avoid straining tubes for radiographs of
this kind it is often expedient, and with small machines necessary, to use
an intensifying screen.
An intensifying screen is a piece of paper or
Tntcnsifyiltg SCfCCns card board covered with some such material as cal-
cium tungstate or platino-barium cyanide. By its
use exposure may be shortened from ^ to 4/5.
The coated side of an intensifying screen is placed against the coated
side of the film, or plate, and both screen and film are placed in the light-
proof packet as usual. Thus we get a double action on the film when
it is exposed, the action of the X-rays themselves and the action due to
the fluorescence of the intensifying screen.
When using an intensifying screen the uncoated side of the film
should present toward the object being radiographed. This is contrary
to the rule that to obtain the best results the coated side of the plate or
film should present toward the object to be radiographed.
The advantages of the intensifying screen are: (i) Just in propor-
tion as it reduces the time of exposure it protects both patient and op-
erator against any ill-effects of the X-rays. (2) By shortening the time
of exposure the life of the tube is lengthened. (3) By using an intensi-
fying screen one is able to do tolerably rapid work even with a small coil.
The disadvantages of the intensifying screen are: (i) It causes a
granular appearance of the negative, blotting out detail. (2) It is liable
to spot the negative, due to unequal fluorescence of its surface. (3) It
fluoresces for a minute or so after exposure, and if the plate and screen
do not maintain their exact relation to one another blurring of the nega-
tive results. (4) For intra-oral dental work unless one owns several
screens, so that a number of film packets may be made at a time, their
use necessitates the making of a film packet before each exposure, which
is discommoding.
Such grosser lesions as an impacted tooth, for example, can be
radiographed satisfactorily with the intensifying screen, but when we
wish to obtain detail, such as is necessary to observe pulp stones or a
necrotic condition, for example, the use of the intensifying screen is
contraindicated. An intensifying screen disintegrates with use.
Because, as I have said, the intensifying screen fluoresces for some
time after the exposure has been made it has been the practice of radiog-
raphers to lay the plate and screen aside for some time before disturbing
their relation to one another. Dr. Sidney Lange, however, believing that
the continued fluorescence will cause blurring of the negative even
though the relation of the screen to the plate be not disturbed, removes the
plate from the screen immediately after exposure. His results from this
practice are excellent.
Figure 117 is a dental radiograph made with an intensifying screen.
Intensifying screens should be cleaned often by brushing the sensitive
side with a very soft brush.
128
DENTAL RADIOGRAPHY
Unless the reader desires to master the method
Pertinent JIdVice. of determining the time of exposure by the milli-
ampere-second method (see Appendix to Chap. V,
Page 355) the most practical advice I can give is: Learn from the
manufacturer of the coil where to set the rheostat and the time
he considers right for dental radiographs. Make an exposure, giv-
ing the time of exposure advised. Develop the film in Eastman
M. Q. tube developer, 6 fluid ounces of water to the tube of devel-
oper, for 5 minutes ; or use the Brady " four-minute " developer for 4
minutes, or the Brady "6-minute" developer for 6 minutes. Remove
from the developer, dip in water and fix in the fixing solution. Now then
if the film is too pale, as it probably will be — for most manufacturers
seem to think their coils will make dental radiographs in shorter ex-
posures than is really necessary or best — increase the time of exposure, or
advance the rheostat, or shorten the distance between the target and film
Fig. 117. Dental radiograph made with an intensifying screen.
and try again. If the negative is too dark, and it has been left In the
Eastman developer only 5 minutes or the Brady developer only 4 or 6
minutes, the exposure has been overtimed.
ItlaKiitd tl)c negatii^c.
The subject of making negatives has already been covered fairly
well in Chapter IV.
What developer shall we use? I obtained the
Choice of Developer, formulas for the developers used by twelve different
radiographers, and they were all different ! From
this we may conclude that any clean, properly mixed developer will do
the work.
However, I would advise the beginner to use one of the developers
just referred to in the foregoing, i. e., a developer which will have the
desired action in a known length of time. When making the developing
MAKING DENTAL RADIOGRAPHS
129
Fig. 118. Dark box for use where a dark room is not available.
solution, dis.solve the light powder first, then the heavier, white powder.
As the operator becomes acquainted with the technic of development he
can correct slight mistakes in exposure by leaving the plate, or film, in the
developer, say, for example, only 4 minutes in the 5-minute developer
for overtimed films, or 7 minutes for undertimed films. It is unnecessary
to leave any plate or film in the 5-minute developer longer than 10
minutes. If the image does not appear as it should in 10 minutes it
never will ; a longer exposure must be made.
If at all possible it is desirable to have a dark room, but if such a
room is not available, a dark box may be used. Fig. 118.
Figure 119 illustrates a satisfactory method of hanging film negatives
up to dry.
130
DENTAL RADIOGRAPHY
To expedite handling it, when the film negative is dry it may be
mounted between 2 pieces of clear glass using passe-partout strips to bind
the pieces of glass together or it may be placed in a special radiomount.
Figure 120.
If several radiographs are made of the same patient it is best to
mount them all between two pieces of glass of suitable size, (Fig. 121)
or in a mount of celluloid and card board. (Fig. 121A.)
Film 119. Films hung up to dry.
Summary Of Steps in (0 Pose the patient. (2) Test the current
tecbniC for niakiug through the X-ray tube. (3) Place the film or plate
Radiographs- in position. (4) Make the exposure. (5) Make the
negative. (6) Prepare the negative for observation and study.
In appearance and size the Van Woert develop-
"i2!!.5-?n''!?S'^* ing tank for dental X-ray films is not unlike the
Developing vanK. * , , , . , \ „ . , ,, ,
metal box m which we buy Colgate s shavmg
stick." In principle it is a light-proof metal box into which a liquid may
be poured without opening the box and admitting light.
Both hands are placed in a light-proof " mufif "
technic. in which " muff " the film packet is unwrapped, the
little tank opened, the films placed in it, and the
tank closed. The tank can now be removed from the " muff " and the
films inside are protected from light. Pour developing solution in the
tank, leave for about 5 minutes, pour out the developing solution. Adjust
a screw and water can be washed through the tank. Next pour in the
fixing solution and leave 5 or 10 minutes. Pour out the fixer and wash
MAKING DENTAL RADIOGRAPHS
131
with water again, when the tank may be opened and the developed film,
the negative, observed.
The Van Woert tank is a very practical device for the general
practitioner of dentistry who does a limited amount of radiodontic work.
REFERRED BY.
DR. HOWARD I
DENTAL RADIOGRAPHER
AND DIAGNOSTICIAN
11 W. NORTH Street
Indianapolis
Indiana
DENTAL
TRADE "RADIOMOUNT" MARK
Fig. 120. Radiomount to hold dental X-ray negatives.
on films only ; and in offices where there is not sufficient space available
for a dark room and where even a daylight developing box (Fig. 118)
would be in the way, the little tank will be most welcome. (See Fig. E.)
132
DENTAL RADIOGRAPHY
f
Fig. 121. Negatives mounted between glass for s-tudy and convenience in handling.
miJc%nSffli t hardening solution is made by dissolving 2
Use Suggested by °^- ^* potassium carbonate m 2 oz. of water. 1 his
Dr. Uan Uloert. should be filtered and kept in a tightly corked bottle.
After removal of the negative from the fixing solution it should be
v^ashed in watei 5 or 10 minutes before being placed in the hardener.
Put enough of the hardening solution in a small beaker or saucer to
MAKING DENTAL RADIOGRAPHS
'^2>2>
134
DENTAL RADIOGRAPHY
^w^- I /
'^a.
%/. — '
-, /■ , \
\ \
-'U
Fig. E. Van Woert technic illustrated. Cut No. 1 shows the hands placed in the muff. Cut No.
2 shows the hands inside of the muff. Cut No. 3 shows the films unwrapped and being
placed in the tank. Cut No. 4 shows the tank closed after the films have been placed in it;
the tank, with the films in it, may now be removed from the muff.
MAKING DENTAL RADIOGRAPHS 135
cover the negative. Leave the negative in the hardener three minutes,
when it may be removed and the surplus moisture absorbed by blotting it
between pieces of blotting paper. Wipe the emulsion side with a lintless
napkin such as the Johnson and Johnson mouth napkin. This process of
hardening and immediate drying may be used where the radiograph is
required immediately. For such negatives as are to be preserved, they
should be washed and dried in the usual way.
ndf antagcs of Tilm
The advantages of the small dental radiographs
RadiAaraMh< made on films held in the mouth over the large plate
9 "'' ♦ radiographs are : ( i ) There is no superimposition
of shadows, and therefore a clearer, better radiograph can be made on
the small film. (2) The patient may be seated in the dental chair while
the exposure is made when small films are used. (3) The time of
exposure is shorter for the small film. (4) Small machines with which
it is necessary to make an exposure of one minute or longer for large
plate radiographs will make a good dental radiograph on a film held in
the mouth in from about 10 to 30 seconds. (5) A compression diaphragm,
though always a valuable appliance, is not so essential when small films
are used as it is when large plates are used. (6) The negative on
celluloid cannot be broken.
flawantage of Plate
The great advantage of the large plates over
Radioarauhs ^^^ small films is that a larger field can be pic-
Scratcbing
Tilm nedatim.
As the small dental films lay in the bottom of
the trays, during the process of development and
fixing it becomes necessary to pick them up re-
peatedly. As this is done, the finger nail sometimes slips off the edge,
across the coated surface of the film, so spoiling the negative or at least
mutilating it in a very undesirable manner. With practice one may
acquire the knack of picking up film negatives when they lay flat on the
bottom of the tray without scratching them, but my assistant has
developed a very simple and satisfactory way to pick them up which
entirely eliminates the probability of scratching them.
Wash the emulsion ofif an old negative, or better, take a piece of
celluloid thicker than that used to make films and fasten a hook clip,
such as is illustrated in Fig. 119 to hang up negatives, to it. This little
device my assistant calls a "scooter," which seems to me a very fitting
name, for, holding to the metal clip the piece of celluloid may be
"scooted" under films, and so they may be lifted from the bottom of
trays with great ease. The hooked part of the clip may be placed over
the edge of the tray so the "scooter" is not misplaced but is always in
position ready for use when needed.
CHAPTER VI.
Kexding Hadiograpbs.
Seeing things is truly a mental effort. Though an object or shadow
be reflected on the retina of the eye, it is not "seen" unless it has an effect
upon the brain. When we say, "train the eye" to see such and such a
thing, we mean really, train the mind — the brain.
To correctly read a radiograph, to see all there is in it to be seen,
and to understand it to mean what it stands for, requires experience and
an intimate knowledge of the anatomy and pathology of the parts under
observation. Experience is an important factor. Upon looking over old
negatives, I see many things of interest in them now which I did not
observe a year ago.
It is always advisable to study the negative in
Tlluminating preference to the print. Some of the finest details
Boxes. are lost in the print. The negative may be held up
to a window or an artificial light, or it may be placed
in an illuminating box (Fig. 122) for observation.
While the illuminating boxes on the market are suitable for studying
large plate or film negatives, they are needlessly large and poorly adapted
for studying the small, dental, film negatives. A small illuminating box
can easily be made. A light-proof box, with a window of frosted glass
and a light inside, may constitute the illuminating box. It is well to paint
the inside of the box white, so increasing the power and uniformity of il-
lumination. With the negative held against the frosted glass of the window
on the outside and the light lit inside, one is able to study the negative to
great advantage. Little spring steel clips, similar to the ones used to hold
a slide or a microscope, may be used to hold the negative against the
frosted glass window.
The use of a reading glass in connection with an illuminating box
"will enable one to observe the negative to the best possible advantage.
The denser the part, the deeper will be the
CbC Rdatioe shadow thrown on the film, and, consequently, the
UalUCS Of Dense more transparent the negative in that region. Thus
Jlreas in negatives, in the negative, metal fillings, posts and metal crowns
appear as transparent areas; gutta-percha, cement,
136
READING RADIOGRAPHS
137
enamel and porcelain a little less transparent ; then in the order of their
respective densities, dentin, bone, gum tissue, and, last, the cheek appears
— when it is shown in the negative at all — as the least transparent part,
except that part of the negative on which the X-Rays have fallen directly
without anything intervening except the black paper of the packet. The
contrast between tooth and bone tissue is very marked. Unfilled canals
and pulp chambers appear as dark streaks and areas in the teeth. Filled
canals and pulp chambers appear light. Pulp stones appear as lighter
Fig. 122. An Illuminating Box.
spots in the dark of the pulp canal or chamber. Abscess cavities appear
as dark areas. It is easy to distinguish enamel from dentin, and the peri-
dental membrane can clearly be seen as a dark streak following the out-
line of roots. A bit of calculus in the peridental membrane will appear
as a light spot. This calculus must be on either the mesial or distal side
of a root to be seen. It could not be radiographed if it occurred on the
buccal, or labial, or lingual.
All the foregoing may be seen in good negatives,
ncaatiV)C$ Prints ^^^* ^^^ ^^^^ cannot be seen in prints and half-tones.
and l)alf-tonc I recall distinctly having read an article on Dental
Reproductions. Radiography in which the writer printed a half-tone
and told his readers to ''observe the enamel, the den-
tin and the peridental membrane," The writer of this article wrote his
138 DENTAL RADIOGRAPHY
paper with either a negative or a good print before him, and assumed
that all he saw there would be reproduced in the half-tone. It was not.
The half-tone was so dark that all detail of the picture was lost, and the
best that could be done was to distinguish between bone and tooth struc-
ture. Let us stop to consider the steps in the making of a half-tone pic-
ture and the chance for the loss of detail is apparent. From the negative
a new picture is made on photograph paper, the print. From this another
picture is made on a half-tone plate, and from this the half-tone picture
is printed on paper with ink.
The finest details of a negative cannot be shown in a half-tone, and,
though I have seen many prints that seemed to have fully as much detail
as the negative, there is usually at least a slight loss of minute detail even
in well made prints.
I have stated, that in order to make a half-tone picture it is neces-
sary first to make a photographic print or picture from the negative, then,
from this, to make the half-tone picture. Thanks to the efforts of Dr. Ot-
tolengui and his co-workers, I am able to print a half-tone made directly
from the negative. The difference in the appearance of a half-tone made
from a negative and one made from a photographic print is shown in
Fig. 123 (made directly from the negative) and Fig. 124 (made from
the photographic print, but reversed in the process for easier comparison).
Densities — deep shadows — we have seen appear
Relative UalUCS ^^ transparencies in the negative. The print, or posi-
Of Shadows in tive, is the opposite of the negative. Hence, in
Prints. prints, and half-tones made from them, we see the
deep shadows of metal fillings, crowns and posts ap-
pearing very dark, gutta-percha, cement, enamel and porcelain a little
less dark, and so on. On the print, filled canals appear dark, unfilled
ones light, abscesses appear as light areas, and so on, always the opposite
of the negative.
In order to avoid confusion of the right and left sides when studying
a negative, bear the following in mind : When looking at the negative
from its film side it is as though you observed the part radiographed
from the position occupied by the tube during the exposure. When look-
ing at the negative with the film side presenting towards the light, away
from the eye, it is as though you observed the part from the position of
the film during exposure. This is the case, granting that the sensitive
side of the film presented toward the object radiographed at the time of
exposure, a condition that should always obtain except when an intensify-
ing screen is used.
If the technic previously given is followed, and the sensitive side of
the film or plate be placed so as to present toward the part to be radio-
READING RADIOGRAPHS
139
140
DENTAL RADIOGRAPHY
READING RADIOGRAPHS 141
graphed, and then the negative placed in the printing frame with the
sensitive side up (this must be done, or there will be a loss of detail)
when observing prints, it is as though one looked at the part from the
position of the film or plate during exposure.
When observing half-tones made from photographic prints it is the
same as when observing the prints themselves, unless special steps have
been taken in the process of making the half-tones to reverse the sides,
as was done in Fig. 124. When observing half-tones made from nega-
tives it is the same as observing negatives from the film side.
When looking at radiographs made directly on paper, it is as though
you observed the part from the position of the tube during exposure.
How to mark negatives is a subject that has
markina caused the use of a great deal of perfectly good paper
negatives. and ink. After trying several methods, I no longer
attempt to mark my negatives, but place them in
envelopes and mark the envelopes as desired. The Lumiere Dry Plate
Co. print the following outline on the backs of their envelopes :
No
Name
Address
Date
Case
Tube used
Exposure
Distance of Tube from Plate
Developer
Referred by Doctor
Remarks
I have lately heard of an "X-Ray ink" for marking negatives, but
have been unable to procure any. The desired markings are placed on
the envelopes or black paper covering the plate or film, the marking being
done on the side of the envelope or black paper presenting toward the
sensitive side of the plate or film, so that when the exposure is made the
ink markings are between the source of the rays and the sensitive side of
the plate or film. This ink must, I think, contain some salt of lead or
bismuth, for the X-Rays penetrate it very poorly, and consequently there
is a shadow cast on the negative.
My objection to marking small dental films in this manner is that
occasionally the shadow of the markings will occur in such a place in the
radiograph as to spoil the picture. The older methods of placing wires
bent to form the figures or letters for marking, or a stencil of sheet metal,
between the source of rays and the plate, is highly unsatisfactory, so far
as their application to the marking of small dental radiographs is con-
t42
DENTAL RADIOGRAPHY
cerned. After the negative is made, markings may be scratched in the
film. But, as I said before, no system of marking the negative itself is
as satisfactory as marking the envelope in which it is kept.
One of the most unfortunate limitations of the
Perspective. radiograph is that it lacks perspective. For example,
though we are able to observe the exact mesio-distal
Fig. 135. (Reduced one-half.)
position of an impacted tooth, we are unable to determine its bucco- or
labio-lingual position, with any degree of accuracy.
The closer the object, which is being radiographed, is to the film
during exposure, the clearer the resulting shadow will be. Thus, for
example, if an impacted cuspid lay lingually to the other teeth, and the
film were held inside the mouth as usual, the detail in the picture of the
cuspid would be a little greater than the detail in the other teeth. If the
cuspid lay to the labial, — farther away from the film. — detail in it would
be less than in the other teeth. But, on the whole, this method of deter-
mining bucco- or labio-hnq-ual location is unreliable.
READING RADIOGRAPHS
143
While I agree with Dr. C. H. Abbot, of BerHn, who has done some
writing and experimental work to prove that radiographs are not totally
lacking in perspective, yet I do declare, from the standpoint of their prac-
tical application to dentistry, that they are simply shadow pictures. And
let me here warn you that like all shadows, X-Ray pictures are often ex-
tremely misleading; one might say, for the word seems to fit so well,
treacherous. To eliminate the chance of misreading, because of distor-
tion of the radiograph, it is often expedient to make several pictures of
the same part or field, changing the pose. Even this, however, does not
Fig. 126. A dental fluoroscope. Fig. 127. Shadows of teeth cast on the fluoroscope.
preclude the possibility of misinterpretation. To correctly read radio-
graphs, a man must be, not only a student of radiography, anatomy, his-
tology and pathology, but he must have and use that gift of the gods —
common sense. He must not jump at conclusions, and he should ever
regard the radiograph as a shadow picture, liable to all the apparent mis-
representations of shadows.
A study of Fig. 125 will convince anyone of the lack of perspec-
tive in at least some radiographs. One is unable to determine, from
observing this radiograph, whether the coin pictured is in the flesh of
the hand, on the back of the hand, or in the palm of the hand. Likewise,
from simple observation, it is impossible to tell whether the needle is in,
on, or under the hand. By deduction, we may come to this conclusion :
The coin was nearer the plate, during its exposure, than the needle, be-
cause the outline of the coin is much clearer than that of the needle, and
other things remaining equal, the closer the object being radiographed is
to the plate, the clearer its shadow will be. Still we cannot determine
144 DENTAL RADIOGRAPHY
the exact location of either needle or coin. We know only that the coin
was somewhat closer to the plate, during its exposure, than the needle.
That is all.
The coin lay under the hand on the envelope holding the plate, the
needle on the back of the hand, when the exposure for Fig. 125 was made.
To overcome the fault of the lack of perspective
Stereoscopic and, to some extent, the distortion in radiographs,
KadiOgrapby. one must resort to stereoscopic radiography.
Stereoscopic radiography is the science and art
of making radiographs, which, when observed through a stereoscope, have
perspective. The technic of making stereoscopic radiographs, together
with a discussion of their value and efficiency, will be dealt with at some
length in a subsequent chapter.
A work of this kind would be incomplete with-
Dental out some mention of the dental fluoroscope. The
TlUOroscopC. simplest and most efficient dental fluoroscope has
been designed by Dr. Tousey (Fig. 126). Like
all fluoroscopes, this one depends on calcium tungstate, or platino-barium
cyanide, for its action. A disc of cardboard, coated on both sides with
either of the above named chemicals, is placed between two discs of
transparent glass, and the glasses and cardboard (or fluorescent screen,
for the cardboard becomes a fluorescent screen when it is coated with
calcium tungstate or platino-barium cyanide) held together by means of
a circular band of metal. A handle now, and we have a dental fluoro-
scope, the screen protected against moisture, and either side of it may
be used.
To use the fluoroscope, the operating room should be dark. It is
best that the operator remain in this darkened room for some time until
his eyes become accustomed to the darkness before making the exposure.
Hold the fluoroscope inside of the mouth, and have the tube placed so
that the X-rays will pass through the part to be observed, and strike the
fluoroscope. Fig. 127 shows the fluoroscope and a shadow of the teeth
thrown on it.
The disadvantages of the fluoroscope are :
1. The operator must expose himself to the actions of the X-rays.
2. Either the time for observation must be made very short, or both
operator and patient must be exposed to the rays unnecessarily and
dangerously long.
3. The picture on the fluoroscope lacks detail.
4. No record of the case, other than a mental picture, can be kept',
READING RADIOGRAPHS 145
while a negative may be referred to as often as expediency or neces-
sity demands.
5. From an educational standpoint, the fact that prints, lantern slides
and half-tones can be made from negatives is a great advantage.
To learn to eat olives, one must eat them, so I am told. To learn
to read radiographs, one must read them, and so we pass to the next
chapter, wherein we shall study, in a practical way, the reading of radio-
graphs.
For further consideration o£ reading, or interpreting radiographs, see Appen-
dix, Chapter VI.
CHAPTER VII.
ZM Uses of the Ktidiosrapb in Dentistry.
The use of the radiograph in the practice of modern dentistry is
almost hmitless. Some of the cases hereinafter mentioned are such as
the general practitioner of dentistry might not be called upon to diagnose
or treat oftener than once oi" twice in a lifetime, if at all. But by far
the greater number of them are such as are met repeatedly in the prac-
tice of dentistry.
The radiograph may be used in the following cases: (i) In cases
of delayed eruption, to determine the presence or absence of the un-
erupted teeth. (2) In cases where deciduous teeth are retained long
after the time when they should have been shed, to learn if the succe-
daneous teeth be present. (3) To learn if the roots of children's teeth
be fully formed. (4) To determine whether a tooth be one of the pri-
mary or secondary set. (5) To determine when to extract temporary
teeth. (6) To show the orthodontist when he may move the coming
permanent teeth by moving the deciduous teeth. (7) To observe moving
teeth. (8) In cases of supernumerary teeth. (9) In cases of impacted
teeth as an aid in extraction. (10) To determine the number of canals
in some teeth. (11) As an aid in filling the canals of teeth with large
apical foramina. (12) To learn if canals are open and enlarged to the
apex before filling and to observe the canal filling after the operation.
(13) To determine whether an opening leading from a pulp chamber
be a canal or a perforation. (14) In cases of pulp stones. (15) In
cases of secondary dentine being deposited and pinching the pulp.
(16) To learn if the filling in the crown encroaches on the pulp.
(17) In cases of teeth with large metal fillings or shell crowns which
do not respond to the cold test, to learn if the canals are filled. (18)
To learn if apical sensitiveness is due to a large apical foramen or an
unremoved, undevitalized remnant of pulp. (19) In cases of chronic
pericementitis ("lame tooth"). (20) In cases of alveolar abscess to de-
termine which tooth is responsible for the abscess. (21) In cases of
alveolar abscess to determine the extent of the destruction of tissue —
bony and tooth. (22) In cases of alveolar abscess to learn how many
teeth are involved. (23) In cases of abscess of multi-rooted teeth to
learn at the apex of which root the abscess exists. (24) In cases of
146
THE USES OF THE RADIOGRAPH IN DENTISTRY i^y
abscesses of crowned teeth to learn whether the canals are properly filled.
(25) As an aid in differential diagnosis between chronic alveolar abscess
and pyorrhea alveolaris. (26) To observe destruction of tissue due to
pyorrhea alveolaris. (27) In cases of pericemental abscess. (28) In
cases of persistent suppuration which does not yield to the usual treat-
ment. (In fact in all cases that do not yield promptly to the usual
course of treatment.) (29) To observe the course of a fistulous tract.
(30) To observe the field of operation before and after apicoectomy.
(31) To locate foreign bodies, such as a broach in the pulp canal or
tissues at the apex of a tooth ; a piece of wooden toothpick in the peri-
dental membrane, etc. (32) To determine the presence or absence of
a bit of root imbedded in the gum tissue. (33) To diagnose fracture
of a root. (34) To observe the size and shape of the roots of teeth to
be used in crown and bridgework. (35) As an aid and safeguard when
enlarging canals for posts. (36) To examine bridges about which there
is an inflammation. (37) To observe the field before constructing a
bridge. (38) To observe planted teeth. (39) In cases of cementoma.
(40) In cases of bone "whorls." (41) To locate stones (calculi) in the
salivary ducts or glands. (42) In cases of bone cysts. (43) In cases
of dentigerous cysts. (44) In cases of tumor, benign or malignant. (45)
To observe anomalous conditions, such as the fusion of the roots of two
teeth for example. (46) To observe the location and extent of a necrotic
or carious condition of bone. (47) To diagnose antral empyema. (48)
To observe size, shape and location of the antrum as an aid in opening
into it. (49) To locate foreign bodies, such as tooth roots or broaches,
in the antrum. (50) To observe cases of luxation. (51) In cases of
fracture of the jaw before and after reduction. (52) In cases of anky-
losis of the temporo-mandibular articulation or the joint formed by the
tooth in the jaw. (53) To observe the field of operation before and after
resection of the mandible. (54) In all cases of facial neuralgia with
an obscure etiology. (55) To observe the inferior dental canal. (56) In
cases of Ludwig's angina. (57) In cases of insomnia, neurasthenia,
insanity* and kindred nervous disorders. (58) In cases of periodic
headaches. (59) In cases of facial gesticulatory tic (spasmodic twitch-
ing of a set of the facial muscles). (60) To allay the fears of a
hypochondriac. (61) In cases where the patient cannot open the mouth
wide enough for an ocular examination. (62) In research work to
study osteology, the development of teeth, action of bismuth paste, bone
production and destruction, changes occurring in the temporo-mandibular
articulation when jumping the bite, blood supply to parts, resorption of
*Dr. Upson — Cleveland.
148 DENTAL RADIOGRAPHY
teeth and the causes for it, etc. (63) As a record of work done. (64) In
cases of hidden dental caries.
It is with a mingled feeling of enthusiasm and misgiving that I
now attempt to illustrate the above named uses of the radiograph. It
is not reasonable to hope that half-tones will show all that can be seen
in negatives. As a result, things may be mentioned in the text that
cannot be observed in the half-tones ; but, be assured, all clinical factors
mentioned in the text were observable in the original radiographs.
Thanks to the help rendered by many radiographers, whose
names appear beneath the half-tones, and the practitioners, whose names
are mentioned in the text, I will be able to illustrate almost all of the
above enumerated uses.
In describing cases which have not come under direct personal
observation there is, of course, considerable liability to mistakes. I ask
my readers to bear this in mind.
It shall be my policy to print as few radiographs as possible to fully
demonstrate the different uses. For example, I could print hundreds
of different radiographs illustrating the use " in cases of delayed eruption
to determine the presence or absence of the unerupted teeth." But only
a few will be used, because that is all that is necessary to demonstrate
the value of the radiograph in such cases, and to use more would be
superfluous in a work of this kind.
1. In 0a$c$ of Delayed eruption to Determine the Presence or Absence of tbe
Unerupted Ceetb
Upper, permanent laterals missing in the mouth
Tig. 12$ of a girl, eighteen years of age. Spaces between the
centrals, and the centrals and cuspids. In this case
the deformity seemed particularly distressing because, save for the spaces
between her teeth, the young lady was positively beautiful.
A radiograph (Fig. 128) was made and shows that the laterals are
not impacted in the upper maxilla. It therefore became necessary to
move the centrals together and construct a bridge. Had the laterals
been present in the maxilla, and space made for them by moving the
centrals together, they would probably have erupted into their places.
Had they not erupted after space had been made for them the tissues
covering them could have been dissected away, holes drilled into the
teeth, little hooks cemented into these holes and the teeth elevated
orthodontically.
THE USES OF THE RADIOGRAPH IN DENTISTRY 149
When there seems to be a congenital absence of
Tifl. 129. ^ tooth from the jaw it is expedient — which is ex-
pressing it mildly — to use the radiograph before
constructing and setting a bridge. Failure to do this might result in what
Fig. 128. Congenital absence of the upper lateral incisors. Age of patient, eighteen years.
Fig. 129. Fig. 130.
Fig. 129. Bridge from central to first bicuspid. Unerupted cuspid. The arrow points to a bit
of tooth root. (Radiograph by Ream of Chicago.)
Fig. 130. An upper cuspid in the place of the lateral. A temporary cuspid in the place which
should be occupied by permanent cuspid. The lateral missing from the jaw.
is shown in Fig. 129 — an unerupted cuspid covered with a bridge. Such
a condition as this may or may not cause local inflammation, neuralgia,
or any of a series of inflammatory and nerve disorders. In this case the
bridge covers not only an unerupted cuspid, but also a bit of tooth root.
In a case presented to me an upper permanent
" Tl8. 130. cuspid was seen occupying the place of the lateral
incisor, and a temporary cuspid was in the space
I50
DENTAL RADIOGRAPHY
Fig. 131.
Fig. 132.
Fig. 131.
Congenital absence of the uppei- second bicuspid. Observe the orthodontia appliance
in position. (Radiograph by Lev/is of Chicago.)
Fig. 132. Delayed eruption of an upper second bicuspid. The orthodontia appliance in position
is being used to make space in the arch for the delayed tooth. (Radiograph by Lewis of Chicago.)
Fig. 133. A badly impacted lower second bicuspid, with no space at all for it in the dental arch.
(Radiograph by Pancoast of Philadelphia.)
THE USES OF THE RADIOGRAPH IN DENTISTRY 151
which should have been occupied by the permanent cuspid. A radio-
graph was made (Fig. 130) to locate the missing lateral. It was not
present in the jaw. Though I am not absolutely sure of this, I never-
theless feel quite certain that the permanent lateral was mistaken for a
temporary tooth and extracted when the patient was about seven or
eight years old— a mistake which could not have happened had the dentist
used radiographs.
Fig. 131 proves the absence of a second bicus-
Tlfls. 131 and 132. pid and shows that bridgevvork must be resorted to,
to fill the space. Fig. 132 discloses the presence
of a second bicuspid and shows that it will not be necessary to make a
bridge. As they appeared before radiographs were taken the cases, from
which Figs. 131 and 132 were made, were similar.
Fig. 133, a case of Dr. Cryer's, shows a
TI9. 133. badly impacted lower second bicuspid with no space
at all for it in the dental arch.
With the exception of the third molars no teeth
Tig. 134. are so liable to be delayed in their eruption as the
upper cuspids. For this reason, when making a
radiograph to determine the presence or absence of an unerupted upper
cuspid or an upper or lower third molar, I feel tolerably sure, before I
make the picture, that the tooth will be found somewhere in the jaw.
When the missing tooth is a central, lateral, bicuspid, or lower cuspid, I
am in doubt as to what to expect. My experience teaches me that when
these teeth are missing they are just as likely to be entirely absent from
the jaw as present in it, and simply unerupted. So far, I have never seen
either long delayed eruption or congenital absence of the first or second
molars.*
*Since the first publication of the above, Dr. Ottolengui has reported two in-
teresting cases (Items of Interest, February 19, 1913), from which record I quote
in part, as follows :
"Very shortly after Dr. Raper had published the fore-
going statement, that up to that time he had not seen a case
IniSSilig wherein first or second molars were congenitally absent, a
Tirst lHolar little girl patient of mine came in for her periodical exami-
nation, and I noted that since her previous visit she had
erupted three first permanent molars, but the fourth had not appeared. I imme-
diately began to wonder whether or not I was about to discover an authentic case
of congenital absence of a first molar. I say authentic, because in records of this
152 DENTAL RADIOGRAPHY
kind it is not always that one may be sure that the history is authentic. But in
this particular case there can be no doubt. The child was the sister of another girl
in my care and had been under my observation since she was four years of age.
I have casts of her mouth at the. age of five, which show the primary denture
complete. I may add also that there never had nor has been any caries, and con-
sequently there was no possibility that a molar had been extracted, a suspicion
always warranted when we find a first molar absent from the mouth of an adult.
An ordinary small mouth radiograph was made, and while it did not disclose the
shadow of a molar, neither did it satisfactorily show what really existed. I there-
fore determined to have a large radiograph made, so that we might have a picture
of the entire bone.
Fig. A.
Odontoma in region which should normally be occupied by lower first molar. Patient 8 years
eld. Malposed lower second molar. (Radiograph by Schamberg, of New York City.)
" The patient was sent to Dr. M. I. Schamberg, who made radiographs of both
sides of the mandible, that we might compare them. The radiographs are repro-
duced in Figs. A and B. My surprise may be imagined when I found that in the
region which should have been occupied by the second bicuspid and the first molar,
there was a well-defined composite odontoma. And perhaps even more astonishing
is the position of the molar lying distally of the tumor. Whether this tooth, which
is seen lying horizontally in the bone, is the first molar or the second molar, is a
question that has been raised by an orthodontist of national reputation, a man of
THE USES OF THE RADIOGRAPH IN DENTISTRY 153
keen judgment and well informed as to tooth forms. While I am willing to admit
that this looks more like a first than a second molar, especially when we compare
with the normal side (Fig. B), still I very much doubt that it is the first molar.
The odontoma is more apt to be a composite of the bicuspid and first molar. But
in any event, interesting as this case is, it cannot be entered in the literature as a
record of congenital absence of a first permanent molar, because that tooth is
either in the bone or else is included in the odontoma, whereas by " congenital
absence" I understand to be meant complete non-existence.
Fig. B.
Same patient as for Fig. A, opposite side, conditions normal.
New York City.)
(Radiograph by Schamberg, of
" The second case which I am permitted to report is
fniSSSing from the practice of Dr. Thaddeus P. Hyat, and is in the
Second molars. hands also of Dr. George B. Palmer for orthodontic treat-
ment. The patient is a boy of fourteen, and we are assured
that no permanent teeth have been extracted, yet no less than thirteen permanent
teeth are missing. In the upper jaw the absent teeth are : both lateral incisors,
three bicuspids, both second molars and both third molars, a total of nine teeth
(note that both upper laterals are absent, while both upper cuspids are present).
In the lower jaw the following teeth are absent: the first bicuspid and the third
molar on the right side and the second bicuspid and the third molar on the left side.
154
DENTAL RADIOGRAPHY
" Figs. C and D are radiographs of the two sides of the head. In the upper
the first molars are easily distinguished, but there are no evidences of the second
and third molars. In the mandible the third molars are absent, but the other four
molars are present, though in one case the crown has been lost by caries. Con-
sidering the boy's age, this seems to be an authentic record of congenital absence
of two second upper molars, and of all four third molars, as the extraction of any
of these teeth could not have been forgotten.
Fig. C.
Patient's age 13. Right side.
Missing teeth: Upper bicuspids, second and third molars. Lower
first bicuspid and third molar.
" Dr. Hyat has kindly asked another patient of his to
lDi$$in9 f\V$t, call at my office that I might examine a very similar case.
Second and in this instance the patient is a woman about thirty-five
€bird I1l0l(lt*$. years of age. She is a highly cultured person engaged in
the editorial department of one of our leading magazines.
She is quite positive that the only tooth she ever had extracted was one lower first
molar. If this be true she has fourteen teeth congenitally absent as follows : In
the upper jaw the missing teeth are the two lateral incisors, the first, second
and third molars on the left side, and the second and third molars on the right
side. In the lower jaw the missing teeth are the second bicuspid and all three
THE USES OF THE RADIOGRAPH IN DENTISTRY 155
Fig. 134 is representative of a class of delayed eruption that is most
common. I could print hundreds of radiographs of such cases. Fig.
123 was a beautiful example. The age of the patient in this particular
case (Fig. 134) was some months over fourteen. The radiograph was
made for an orthodontist who was just beginning treatment of the case.
There was no evidence of the presence of the cuspid and no room for
it to erupt. When the arch was broadened and space made for it the
Fig. D.
Same patient as for Fig. C, left side. Missing teeth: Upper second bicuspid, second and third
molars. Lower second bicuspid and third molar. The roots only of the lower first molar
remain.
cuspid erupted. It required some mechanical guidance to make it come
into its exactly proper position.
molars on the right side, and both bicuspids and the third molar on the left side
Again we have the upper laterals missing, and the upper cuspids present.
" In this mouth we have the strange anomaly of three molars missing from
the upper jaw on the right side, and three molars missing from the lower jaw on
the left side. Enumerated in full the absent molars were all four of the third
molars, three of the second molars and two of the first molars."
156 DENTAL RADIOGRAPHY
The mere making of space for them in the arch will usually result
in the eruption of unerupted teeth, unless they are malposed. If, after
space is made, the tooth does not move, the gum and process over it
should be slit surgically. If this does not suffice to induce eruption,
the soft parts and process must be cut away, and sometimes it may be
necessary to resort to the use of orthodontia appliances to assist erup-
tion, as formerly suggested.
In handling cases of unerupted teeth it should constantly be borne
Fig. 134. Age of patient, fourteen. An unerupted malposed cuspid. No room for it in the
dental arch. Observe the tipping of the lateral, which is probably due to the pressure of the
cuspid against the apex of its root.
in mind that it is an almost invariable rule that unerupted teeth move
only in the direction in which they point ; i. e., " In a line with their long
axis." Thus an unerupted tooth must be headed right, or pointed right,
to induce it to erupt.
When radiographing cases of delayed eruption we may expect to
find (i) the tooth present in the jaw — Fig. 134; (2) the tooth missing
from the jaw — Fig. 131 ; (3) an odontoma in the place of the tooth —
Fig. A ; (4) an odontoma or supernumerary tooth preventing eruption
— Figs. 263 and 264.
THE USES OF THE RADIOGRAPH IN DENTISTRY 157
2. Tn 0a$e$ lUbcre Deciduous teeth are Retained Cong :Hfter the time lUben
they Should I)ave Been Shed, to Cearn if the Succedaneous
teeth be Present.
Case — Girl, age seventeen, large cavity in
Tig. 135. upper, second, deciduous molar. Whether to fill this
tooth or extract it depended on whether there was
a second bicuspid to take its place in case of extraction. It was not at
all loosened and there was no visible evidence of the presence of the suc-
Fig. 135.
Fig. 136.
Fig. 135. Age of patient, seventeen. Retained upper, second, temporary molar. The radiograph
sliows that the second bicuspid is present in the jaw.
Fig. 136. Age of patient, twenty-one. Retained lower, second, temporary molar with a large
cavity in the crown of the tooth and the roots almost entirely resorbed, despite the fact that
there is no oncoming second bicuspid.
ceeding bicuspid. Fig. 135, however, shows the bicuspid to be present.
The half-tone may not do so, but the negative now before me has per-
spective enough for me to see that the bicuspid is being deflected toward
the lingual. The deciduous tooth was extracted and the bicuspid erupted
promptly.
Case — young man, age twenty-one, lower, sec-
Tifl. 136. ond, deciduous molar with pulp exposed. Question :
Should the tooth be treated, filled and retained in
the mouth, or extracted to make room for the second bicuspid? Fig.
136 demonstrates the futility of attempting to treat the tooth — its roots
are almost entirely resorbed despite the fact that there is no succedaneous
tooth in the jaw — and shows also that there is no bicuspid to take its
place. Extraction and bridgework are indicated'.
Fig. 137 shows two retained temporary up-
Tig. 137. per cuspids with the permanent cuspids impacted and
malposed.
158
DENTAL RADIOGRAPHY
Fig. 138 shows two retained, primary, lower
TI9. 13$, central incisors with no sign of the permanent cen-
trals. Age of patient, seventeen.
Case — a young man, age twenty-two; with a
Ti9$. 139 and mo. retained, temporary, lower, second molar. The tem-
porary tooth was too short to reach its antagonists
in occlusion. For this reason the patient, a dental student, wished to
have it crowned. Before making the crown, a radiograph was taken (Fig.
Fig. 137. Fig. 138.
Fig. 137. Two retained temporary cuspids, with the permanent cuspids impacted and malposed.
(Radiograph by Lewis, of Chicago.)
Fig. 138. Two retained temporary, lower, central incisors. No permanent centrals present.
Age of patient, .seventeen. (Radiograph by Blum, of New York City.)
139) after the development of which it was seen that the making of a
crown was not indicated. From the appearance of the radiograph one
might suppose that the temporary tooth was loose — its roots being almost
entirely resorbed. But such was not the case.
Fig. 140 is a radiograph of the same case one month after the
extraction of the temporary molar. Notice how rapidly the bicuspid is
erupting into its place. The force of eruption, which had been held in
abeyance for about eleven years, became promptly active upon removal
of the abating object.
Case — young man, age twenty-one. A retained,
Tigs. 141 and 142. temporary, upper cuspid with no observable sign of
the succedaneous cuspid. A radiograph was made
(Fig. 141), but, being a poor one, it failed to show the looked-for tooth.
Yet from the reading of this radiograph I was able to state with a mod-
erate degree of certainty that the cuspid was present in the jaw. If the
THE USES OF THE RADIOGRAPH IN DENTISTRY 159
tooth itself cannot be seen, what is there in the picture to lead one to
believe that the permanent cuspid is present? The arrow points to the
upper end of a dark line. The dark line represents dense bone and such
a line almost always is to be noted in radiographs of impacted teeth.
Fig. 139. Fig. 140.
Fig. 139. Retained temporary, lower, second molar, with the succedaneous tooth beneath it. Age
of patient, twenty-two. The dark spots in the temporary tooth and two permanent molars are
metal fillings. All of the mesial root and some of the distal root of the temporary tooth resorbed.
Fig. 140. The same as Fig. 139 one month after extraction of the temporary tooth. Observe
how rapidly the bicuspid is erupting. .When this picture was made it could be seen in ine mouth.
Fig. 141. ^^^^^^^^
Fig. 143.
Fig. 141. Age of patient, twenty-one. A retained temporary upper cuspid. The arrow points to
a dark line following along the side of the impacted cuspid. The impacted tooth itself cannot
be seen.
Fig. 142. The same as Fig. 141, but taken at a diiferent angle and showing the permanent cuspid.
To verify or disprove my deductions another radiograph was made
(Fig. 142), which shows the impacted cuspid clearly.
The question arises naturally, What operative procedure should be
i6o DENTAL RADIOGRAPHY
resorted to in such cases as the one just described? Had the patient
been younger, or had the root of the temporary cuspid been much resorbed,
or had the pressure of the impacted tooth been causing resorption of
the permanent lateral root, or central root, or had the patient been suf-
fering from neuralgia, periodic headaches, or any nervous disorder —
had any of these conditions existed the temporary tooth should have been
extracted immediately, space made in the arch for the permanent tooth
and such orthodontic assistance given as might prove necessary to cause
it (the permanent cuspid) to erupt into its proper place. As none of
Fig. 143. The roots of a lower, first, permanent molar not quite fully formed. Age of patient,
eiglit years and four months. Only the crowns of the second bicuspid and second molar are
formed.
these conditions did exist, and as the patient expressed a definite disin-
clination to have anything done unless absolutely and imperatively neces-
sary, the case was dismissed with the understanding that the condition
should be kept under rigid observation. The man may go through life
without trouble, or inside of a year he may be suffering almost any
nervous disorder from simple neuralgia to insanity* ; or he may lose
the temporary cuspid as a result of the resorption of its roots, or he
may even lose the lateral or central as a result of absorption of their
roots, or suppuration may occur.
3. to Cearn if tb( Roots of Children's teetb arc Tully Tormcd.
Case — patient, eight years and four months old.
Tl|. 143. A large cavity in a lower first, permanent molar.
To remove absolutely all of the decalcified dentin
meant extensive exposure of the pulp, and, therefore, pulp devitaliza-
tion, extirpation and canal filling. But should we practice pulp devitali-
zation in such a case ? If the roots of the tooth are fully formed, yes ;
*Dr. Upson.
THE USES OF THE RADIOGRAPH IN DENTISTRY i6t
if the roots are not fully formed, no. A radiograph (Fig. 143) was
made and shows that the roots of the tooth are not quite fully formed.
Accordingly exposure of the pulp was avoided, the unremoved, decalcified
dentin painted with silver nitrate, a paste of zinc oxide and oil of cloves
placed in the bottom of the cavity and the tooth filled with cement, the
object of this treatment being to conserve the pulp in the tooth at least
until the roots are fully formed.
Often a child meets with some accident which breaks off the angle
of a central or lateral incisor. To restore the angle sometimes necessi-
Fig 144. Post-collar crown on a temporary cuspid root. The permanent cuspid erupted down
to the post of the crown. The dark shadows in the region of the temporary cuspid crown are
numbers used to mark the negative. (Radiograph by Kells, of New Orleans.)
tates the removal of the pulp and the placing of a post in the canal. The
question should always be raised, "is the tooth's root fully formed?"
If it is, we may proceed with the devitaHzation, but if not, some tem-
porary restoration should be made and the pulp conserved until it has
fulfilled its function of root development. Whether the root is fully
formed or not can be determined only by the use of the X-rays.
In a child's mouth we occasionally find an anterior tooth so badly
decayed that crowning is indicated. Again we are confronted with the
question, "is the root fully formed?" And whether we should devitalize
and crown the tooth or keep it patched with cement for a year or so
depends entirely upon the answer which the radiograph may make to
this question.
4. to Determine lUbetber a tooth be One of the Primary or Secondary Set.
What treatment we give a tooth depends very largely on whether
it be of the permanent or deciduous set. If a man knows his dental
anatomy as well as he should it is usually easy for him to determine
whether a tooth be a primary or secondary one. Occasionally, how-
ever, we find a tooth (usually an upper lateral incisor) that looks as
i62 DENTAL RADIOGRAPHY
much like a member of one set as the other and the radiograph must be
used to arrive at a definite conclusion. To mistake a permanent tooth
for a deciduous one and extract it (Fig, 130) is an inexcusable and dis-
astrous blunder.
Sometimes a tooth is so badly decayed (the crown may be entirely
destroyed) that it is impossible to determine by simple ocular observa-
tion whether it be a temporary or a permanent one. The radiograph can
be used to great advantage in such cases. If the carious tooth be one
of the temporary set, with the succedaneous tooth ready to take its place,
it should be extracted. If the carious tooth be a permanent one, the
radiograph shows the size and condition of its roots.
Case — a post-collar cuspid crown became loose.
Tig. 144, A radiograph (Fig. 144) was made and shows that
the crown is placed on a temporary cuspid root. Part
of the root of the temporary tooth is resorbed and the permanent cuspid
has erupted down to the end of the post of the crown. The very dark
shadows in the region of the temporary cuspid crown are caused by lead
numbers placed against the film packet to mark the negative.
5. Co Determine (Uben to Extract temporary teetb.
The best rule ever formulated for the extrac-
Tlg. 145. tion of deciduous teeth reads, "Extract a deciduous
tooth only when its successor is ready to take its
place." There are many cases where the operator is able to detect the
presence of the succedaneous teeth by ocular and digital examination.
In about as many cases, however, the only way to determine the presence
of such teeth is by the use of the radiograph. Thus the rule just quoted
is one which, when followed, necessitates the use of the radiograph. Fig.
145 is of a case where extraction of the temporary first molar is indicated,
and extraction of the temporary second molar is contraindicated. The
temporary second molar should not be removed for a year or so — not
until the second bicuspid is just ready to take its place.
Often in practice we are confronted with abscessed temporary teeth.
The age of the patient is such that we cannot decide whether the tieeth
are loose as a result of the abscessed condition, or because of resorption
of the roots and the presence of the succedaneous teeth. A radiograph
of the case will enable us to decide, and our treatment will be governed
accordingly. Not only will the radiograph show the operator when de-
ciduous teeth should be removed, but will aid him in their removal —
especially in cases where the temporary teeth are badly decayed — by
showing the exact size and location of the temporary teeth's roots and
the position of the succedaneous teeth.
THE USES OF THE RADIOGRAPH IN DENTISTRY 163
6. to Sbow m Ortboaontist Ulbcn f,z may move tbc eoming Permanent Ceetb by
mooing tbe Deciduous teetb.
It impressed me very much when I first heard of radiographically
observing, and then regulating, teeth before their eruption. I heard of
this in a lecture by Dr. Ottolengui. I quote Dr. Ottolengui :
"One of the difficult operations which confronts
Tig. 146. the orthodontist at times is the bodily movement of
the bicuspids buccally. Very often in the past at-
Fig. 145. This picture shows that the temporary first molar may be extracted. The tem-
porary second molar should not be extracted for a year or so, when the second bicuspid will
be just ready to take its place. (Radiograph by Lewis, of Chicago.)
tempts to widen the arch, after the eruption of the bicuspids, has resulted
in tipping the crowns buccally, the apices of roots remaining in the orig-
inal apical arch. Hence, one of the chief advantages of early orthodontic
interference lies in the fact that the temporary molars may be moved
buccally, carrying with them the underlying bicuspids, and this advantage
is made more clear if it be recalled that at this period the bicuspid roots
are but partly formed. Even when the roots of the temporary molars
are already considerably absorbed, still enough may be left to serve to
deflect the oncoming bicuspids in the direction desired.
"This slide (Fig. 146), from the collection of Dr. Matthew Cryer
(radiograph by Pancoast, of Philadelphia), shov/s nicely the usual rela-
tion of the erupting bicuspids to their predecessors, the temporary molars.
It will be noted that the apices of the bicuspids are still unformed, and it
is clear that if these teeth can be led into proper positions during eruption,
the formation of the apices afterward afifords the most permanent 'reten-
tion.' A casual glance at the upper temporary molars might create a
doubt as to the probability of moving the unerupted bicuspids, but there
is an easily overlooked factor, viz., the palatal roots of these molars do
164
DENTAL RADIOGRAPHY
not show in radiographs of this region at this period, because they lie be-
hind the crowns of the bicuspids ; that is to say 'behind,' in relation to
the source of light, the X-ray tube."
Fig. 1-16. Radiograph made to show relation of temporary molar roots to advancing bicuspids.
(Collection of Dr. Cryer. Radiograph by Pancoast, of Philadelphia.)
7. to Observe mopIng teeth.
Fig. 147 demonstrates the congenital absence of
Tigs. 147, 14$ and 149. the upper lateral incisors. The orthodontic appliance,
seen in the radiograph, is being used to draw the
centrals together. It was highly important in this case that the teeth be
THE USES OF THE RADIOGRAPH IN DENTISTRY 165
moved through the alveolar process en masse, and not tipped. The
movement desired was one which would make the roots parallel when
the crowns of the teeth came together, so that posts could be set in the
canals of the central incisors, and a bridge made to restore the lost lat-
erals. Fig. 148 was taken about a month after Fig. 147. It shows that
the teeth have been moved together, but there is too much tipping of the
Fig. 147. Fig. 148. Fig. 149.
Fig. 14 7. Congenital absence of upper lateral incisors. The orthodontic appliance seen is being
used to draw the central incisors together.
Fig. 148. This radiograph was made one month after Fig. 147. It will be seen that there has
been considerable movement of the teeth. The left central is tipped considerably.
Fig. 149. Made one month after Fig. 148. The central incisors are together and their roots
almost parallel.
left incisor — not enough movement of the tooth at the apex of the root,
compared to the movement of the crown. It, therefore, became necessary
to modify the force which was being used. This was done, and Fig. 149
shows the teeth together and the roots almost parallel.
A case in the practice of Dr. C. Edmund Kells,
Tigs. 150, 151 and 152. Jr., and reported by him in the May number of
Items of Interest, 191 i. Fig. 150 shows a mal-
posed permanent cuspid above the temporary cuspid, the root of which
is somewhat resorbed. Age of patient, eleven years. Fig. 151 was
made one year and seven months after Fig. 150. "Compare this pic-
ture with Fig. 150, and it will be seen that the permanent cuspid has
migrated in a line with its long axis," causing resorption of the perma-
nent lateral root. The temporary cuspid was extracted, but the perma-
nent tooth did not erupt into its position in the arch. It was, therefore,
concluded that the tooth "would have to be brought down by some
mechanical means." Accordingly, the gum tissue and overlying process
were "slit down to the cuspid and then gently spread apart, and the
i66
DENTAL RADIOGRAPHY
cuspid was exposed to view. A piece of iridio-platinnm wire was
then shaped, as shown in Fig. 152, and the hook was worked supposedly
under the mesial prominence of the cuspid, and a rubber ring attached
to the loop on the other end, and secured to a lug on the molar band, all
as shown in Fig. 152, which is a skiagraph of the case with the appliance
Fig. 150. Fig. 151.
Fig. 150. Malposed, permanent cuspid above the temporary cuspid, tlie root of the latter
somewhat resorbcJ.
Fig. 151. Same as Fig. 150 one year and seven months later. Observe that the cuspid has
migrated in the line of its long axis. The permanent lateral root is badly resorbed.
Fig. 152. Same as Figs. 150 and 151 after removal of the temporary cuspid. The wire hooked
over the cusp of the tooth was thought to be placed over the mesial prominence until the
radiograph was made. (See Fig. 459.)
in position. Imagine my surprise to find by this picture that the hook
was not anywhere near where I had thought I put it. Instead of being
well up under the mesial prominence, it was merely caught under the
point of the tooth, and, of course, it slipped off shortly after the patient
left the office. Upon her return a hook ^g of an inch longer was fitted
in place, and this time, with a radiograph as a guide, there was no mis-
take about its placement. The appliance was worn for several weeks, at
THE USES OF THE RADIOGRAPH IN DENTISTRY 167
the end of which time the point of the cuspid having been brought to the
surface of the gum, it was removed and the tooth allowed to erupt by its
own volition. Despite the great destruction of its root the lateral re-
mains firm and apparently healthy."
$. Tn €ase$ of Supernumerary teeth.
A case in the practice of Dr. B. S
Chicago. Patient's age, twelve years.
Partridge,
Tig. 153. Chicago. Patient's age, twelve years. The teeth
wert' being regulated, and the radiograph, Fig. 153,
Fig. 153. Fig. 154.
Fig. 153. A and B, supernumerary tooth bodies. C, the crown of the temporary cuspid.
D, the permanent cuspid. (Radiograph by Lewis, of Chicago.)
Fig. 154. A .and B are supernumerary teeth. (Radiograph by Lewis, of Chicago.)
was taken to determine the presence or absence of the permanent lower
cuspid. A httle supernumerary tooth (A) could be seen in the mouth
occupying a part of the space which should have been occupied by the
permanent cuspid. The two shadows marked "B" are two more super-
numerary tooth bodies. The larger shadow marked "C" is the crown of
the temporary cuspid, which had never erupted. The large shadow to
the left, marked "D," is the permanent cuspid pressing against the side
of the lateral at the apex of its root. The three supernumerary bodies
and the crown of the temporary cuspid (the root was resorbed) were
removed, allowing the permanent cuspid to erupt.
Just lingually to each central incisor is a super-
fig. 154. numerary tooth. One (A) could be seen in the
mouth, but there was no evidence of the other.
Neither central nor lateral incisor roots are as yet fully formed, and the
i68
DENTAL RADIOGRAPHY
laterals have not yet erupted. Indeed, before the picture was made, it
seemed that a peg-shaped lateral was erupting just lingually to the cen-
tral. The radiograph shows this tooth to be supernumerary.
Dr. T. W. Brophy, of Chicago, reports a case of insistent suppura-
tion due to an impacted supernumerary tooth, which was found by the
use of the radiograph. Dr. Brophy calls attention to the fact that a cor-
rect and definite diagnosis could not have been made by any means at our
command except the X-rays. The case recovered promptly upon removal
of the supernumerary tooth. I regret that I have been unable to obtain
radiographs of this case.
fig. (55. An impacted upper fourth molar.
Fig. 155. Fig. 156.
Fig. 155. An impacted upper fourth molar.
Fig. 156. A supernumerary tooth in the canal of a cuspid tooth. (Radiograph by Clarence Van
Woert, of New York City.)
To me this is a most remarkable case — a super-
Tig. 156. numerary tooth in the canal of a cuspid tooth — a
tooth inside of a tooth. The supernumerary tooth
has a root canal, and the crown is covered with enamel. There is no
doubt of the fact stated, because Dr. Van Woert, after radiographing the
case, drilled into the permanent cuspid and found the enamel-covered
supernumerary within. The radiograph is not as good as I wish it were.
The upper two-thirds of the roots of the teeth shows fairly well but there
is a confusion of shadows in the lower third and m the crown.
9. Tn 0a$c$ of Tmpacted teeth as an Hid in extraction.
Impacted, lower, third molar tipped to the
Tig. 157. mesial. The picture shows that in this case a knife-
edge stone in the dental engine could be used to ad-
vantage, cutting away the mesio-occlusal portion of the third molar, and
THE USES OF THE RADIOGRAPH IN DENTISTRY 169
so greatly facilitating the removal of the tooth. Observe the absorption
of the distal surface of the second molar (the light area), due to pressure
against it; and the large abscessed cavity (light area) between the sec-
ond and third molars, extending down to the apex of the second molar.
This radiograph is of particular interest, because it shows so clearly an
abscess caused by impaction.
That the pressure of an impacted tooth may
Tigs. 15$ and 159. ^^^^^^ absorption of the tooth against which the
pressure is brought to bear, is further illustrated in Figs. 158 and 159.
Fig. 157. Fig. 158.
Fig. 157. An impacted lower third molar. The light area between the second and third molars
represents a destruction of bony tissue, arrow A. Arrow B points to a light area, which rep-
resents the absorption of the second molar. (Radiograph by Blum, of New York City.)
Fig. 158. An impacted upper third molar. The arrow points to a light area representing absorp-
tion of the upper second molar. Notice the very poor filling in the first molar; it fills the
interproximal space between the first and second molars. (Radiograph by Ream, of Chicago.)
In Fig. 158 the arrow points to a light area representing absorption
of the upper second molar, due to the pressure of the third molar against
it. A study of this radiograph gives the dental surgeon a good idea of
how he should apply his force in extraction.
Fig. 159 is a case of Dr. Cryer's. I quote Dr. Cryer: Fig. 159
"shows an impacted, lower, third molar resting against the posterior root
of the second molar. It will be seen that the root of the second molar is
much absorbed, which caused considerable trouble. Removal of the sec-
ond molar gave relief to the patient. . . . The upper third molar is
in an awkward position."
Figs. 160 and 161 show impacted upper third
Tigs. 160 and 161. molars. The unerupted teeth lie in the jaws at en-
tirely different angles. The value of such knowledge
to the operator, about to extract, is apparent.
This radiograph (Fig. 162) shows the surgeon
Tig. 162. just how much bone must be dissected away before
the malposed tooth can be removed. Patients seldom
I70 DENTAL RADIOGRAPHY
know that the removal of a tooth is not always a simple operation. They
are therefore inclined to blame the operator if the tooth is not quickly
removed, instead of crediting him with working dexterously on a difficult
operation. They are likewise unwilling to pay a fee in proportion to the
Fig. 159. Impacted upper and lower third molar. Absorption of the distal root of the lower
second molar. (Radiograph by Pancoast, of Philadelphia.")
difficulty of the operation, as compared to other operations. The removal
of the third molar, shown in Fig. 162, is a more difficult operation than the
removal of a vermiform appendix. By showing patients radiographs of
such cases the dentist will gain their earnest, intelligent co-operation.
They will know just what is done for them, and for the first time in their
THE USES OF THE RADIOGRAPH IN DENTISTRY 171
lives they will understand that the extraction of a tooth may be a serious,
difficult and expensive operation.
The following report of this case is by Dr. F. K.
Tifl. 163* Ream, of Chicago. "Patient's age, seventy-two years.
Symptoms : Swelling near symphysis thought to- be
the result of wearing an artificial denture. Considerable pain. Diagnosed
Fig- 160. Fig. 161.
Fig. IGO. Impacted upper third molar.
Fig. 161. Impacted upper third molar. Notice the difference in the position of the impacted
tooth shown in this case and in Fig. 160.
Fig. 162. Fig. 163.
Fig. 163. Impacted lower third molar with its occlusal surface presenting mesially. The
radiograph shows the dental surgeon how much bone must be burred or chiseled away before the
tooth cnn be removed. (Radiop^rpoh by Ream, of Chicago.)
Fig. 163. Impacted bicuspid in an otherwise edentulous mouth. Age of patient, 72 years.
(Radiograph by Ream, of Chicago.)
cancerous by surgeons, and patient advised to go to the hospital for opera-
tion. The radiograph (Fig. 163) shows an impacted bicuspid in the
otherwise edentulous jaw. Operation: Alveolar process burred away
and tooth removed. Result: Immediate and complete recovery."
1^2
DENTAL RADIOGRAPHY
Fig. 164 is a case of Dr. Cryer's. I quote Dr.
Tig. 164. Cryer: Fig. 164 "shows a lower third molar passing
under the second molar and becoming lodged be-
tween the first and second molar, the crown of the third molar pushing
against the root of the first molar. The first molar was extracted, which
cleared up the neuralgia, and the third molar pushed up into the place
of the first molar."
Fig. 164.
Lower third molar lodged between the first and second molars.
Pancoast, of Philadelphia.)
(Radiograph by
Fig. 165 is also a case of Dr. Cryer's. The
Tig. 165. radiograph shows an impacted upper third molar,
with the occlusal surface presenting upwards. Dr.
Cryer's remarks concerning this case are interesting. I quote Dr. Cryer :
Fig. 165 "shows the occluding surface of the upper third molar pointing
upward towards the posterior portion of the orbit. The patient had
been suffering from disturbance of the eye for a long time. Considerable
improvement took place in the eye soon after extraction of the inverted
tooth."
10. Co Determine the number of Canals In Some teetb.
It will be noticed that I say "to determine the number of canals in
some teeth." Of course, it is not necessary to use the radiograph each
THE USES OF THE RADIOGRAPH IN DENTISTRY 173
time we open into a tooth to learn how many canals that tooth may have.
But occasionally I do find it necessary or expedient to use the radiograph
to verify or disprove the existence of some unusual condition suspected.
Fig. 165. Impacted upper third molar with the occlusal surface pointing upward. (Radiograph
by Pancoast, of Philadelphia.)
Case : An upper first ( ?) molar in which but one
•yig. 166. small canal could be found. After searching for the
other two canals for a few minutes, the one canal
was filled with gutta-percha, and a radiograph made (Fig. 166) ; this
shows that the tooth has but one canal. In this case the radiograph saved
considerable work and worry on the part of the operator. The tooth is
probably a second molar moved forward in the place of an extracted
first molar, judging from the manner in which it is tipped and from the
fact that it has only one canal.
This case was in the hands of one of the most
TIfl. 167. expert operators in Indianapolis. The lower first
bicuspid had been devitalized, and the pulp removed.
1/4
DENTAL RADIOGRAPHY
but the tooth remained sore. Radiography was resorted to to learn, if
possible, the cause of the persistent pericementitis. A piece of ligature
wire, such as is used by orthodontists, was placed in the canal and radio-
graph Fig. 167 made. The wire follows the enlarged canal. But this
particular tooth happens to have two canals. The unopened canal is seen
to the distal of the wire. If a man, having the skill of the operator who
handled this case, misses a canal, as this man did, then I firmly believe
that the mistake is one that any man, however skillful, is liable to make.
Fig, 166.
Fig. 167.
Fi?. 166. Upper first (?) molar with but one canal which is filled.
Fig. 167. The dark streak in the first bicuspid is a wire passing into the canal. This tooth
has another canal, which can be seen as a light streak distally to the wire. The more or less
oval dark spot at the neck of the first bicuspid is a buccal cervical filling. The cavity in the
crown of the tooth is stopped up with gutta-percha.
Let me say here that a lower bicuspid, or cuspid with two canals, is
not such an unusual occurrence, as it is generally believed to be. Men
have shown me such teeth, and spoken of them as though they were rare
anomalies. As a teacher of operative technic, I devote a part of my time
to the dissection of teeth. In this work I handle thousands of disasso-
ciated human teeth. In my work of last year, for example, I estimate
that I observed six to eight thousand teeth. And among these I noticed
not less than seven lower cuspids and five lower bicuspids with two
canals each.
Without printing the radiograph, which is not a very good one, I
quote the legend which appears beneath it in the last edition of Buckley's
"Modern Dental Materia Medica, Pharmacology and Therapeutics." "In
this case the author desires to insert a bridge. On opening into the third
molar and second bicuspid, which teeth were to be used for the abut-
ments, we were unable to find any canals in the bicuspid, and only a small
canal in the molar. The skiagraph confirms the clinical findings."
THE USES OF THE RADIOGRAPH IN DENTISTRY 175
IK m an Jlia in Tilling the €anal$ of teetb witb Carac Jlpica) Toramina.
To demonstrate this use of the radiograph a
Tig. 16$. central incisor with a large apical foramen was
chosen, and an orthodontic ligature wire passed into
the canal until the patient received sensation. The worthlessness of the
"sensation test," as a guide in filling to the apex of canals is demonstrated
by Fig. 168, which shows the wire penetrating the tissues four or fi^^e
millimeters beyond the apex of the tooth. After the radiograph (Fig.
168) was made, the wire was removed, and that part of it penetrating the
apex cut off, or as nearly as could be judged from the appearance of the
radiograph.
Fig. 168. Fig. 169. Fig. 170.
Fig. 168. A wire passing through a large apical foramen in an upper, centra! incisor, extending
several millimeters into the tissues above the apex of the root.
Fig. 169. The same" case as Fig. 168, after the wire has been removed, a part of it cut off
and reinserted into the canal. The wire reaches just to the apical foramen.
Fig. 170. The same case as Figs. 168 and 169, showing a canal filling of gutta-percha closing
the apical foramen, not penetratir.g through it, and not leaving a little ot the canal unfilled
at the apex of the root. The entire canal is not filled, because there is to be a post set in it.
Next the shortened wire was reinserted and an-
Tifl. 169. other radiograph (Fig. 169) made. This shows that
my judgment in cutting off the wire in this particular
case was unusually good. The wire reaches just to the apex. It may be
necessary to make two or three trials before the wire is placed just to
the apex.
With the length of the wire as a guide to the
Tifl. 170. length of the root, the proper distance was measured
on a canal plugger, and the distance marked on the
plugger by passing it through a little piece of base-plate gutta-percha,
stopping the gutta-percha on the plugger at a distance from its end equiv-
alent to the length of the wire. The end of the canal plugger was then
176
DENTAL RADIOGRAPHY
warmed slightly, and brought in contact with a small piece of gutta-
percha canal point. With the piece of gutta-percha so fastened on the
canal plugger, it was carried into the canal a sufficient distance to reach,
but not pass, beyond the apex. (Fig. 170.) A slight twist of the plugger
will disengage it from the gutta-percha, when the latter may be tamped
firmly, but not too forcibly, to place. No further filling of the canal was
done in this case, the canal being left open to receive a post.
What will happen if the canal filling either fails to reach the apex or
passes a little beyond it ? An abscess may result. If the canal filling fails to
reach the apical foramen, in such cases as the one just described, an abscess
is very Hkely to occur. If perfectly aseptic gutta-percha is used as a
Fig. 171
Fig. 172
Fig. 171. The dark streaks in the lower molar are wires in the canals. (Operator, Dr. Moag,
Indianapolis.) Fig. 172. The same as Fig. 171 after canal filling.
canal filling, and the tissues above the apex are not infected, then the
passage of a little gutta-percha into the apical tissues will probably not
result in suppuration or even inflammation, so well do tissues tolerate
gutta-percha. But the fact remains : The ideal canal filling is one which
fills the canals, neither falling short of the end of the root nor passing
beyond it. (For further consideration see Appendix Chap. XI.)
12. to Cearn if 0anal$ Jlrc Ooen and enlarged to tbe Bptx Before Tilling, and to
Observe the 0ana1 Tilling JIfter the Operation.
A radiograph of the tooth before attempting to open its canals will
often be found of great value to the operator. This is particularly true
in cases where the shape or size of the roots is unusual.
At any time during the process of opening canals the operator may
insert wires and make a radiograph to see how far he has penetrated.
THE USES OF THE RADIOGRAPH IN DENTISTRY i^j
Fig. 1 71 is the first radiograph made of the particular case it ihustrates,
and shows the wires (in this case old broaches) reaching the ends of the
canals.
A wire Avith a flat end does not enter canals readily. Engage the
wire — orthodontia ligature wire for example — in the broach holder, for
the dental engine suggested by Dr. Gallic, hold the end of the wire
with emery cloth between the thumb and finger, and revolve the engine.
In this way the wire may be pointed and reduced to any desired size.
It is not always a physical possibility to reach the ends of the canals
in molar teeth. It is very often necessary to devote from five to ten
hours on a molar to open its canals to the end.
Fig. 173. Canals in an upper first molar well filled. (Operator, Dr. Emmert, Indianapolis.)
Fig. 174. Wire passing to the mesial through a perforation in the mesial side of the mesio-
buccal root of an upper first molar.
Even after the canals are open to the end, the fact having been
demonstrated with diagnostic wires and radiographs, it is not at all un-
common for the operator to fail to fill the canals the first time he tries.
Dr. M. L. Rhein, of New York City, was, as far as I am able to
learn, the first man to make routine use of the radiograph in pulp canal
work.
The advantages in using the radiograph in this connection are as fol-
lows : Much guesswork is eliminated — we know what we are doing.
If the canal is tortuous, and we start through the side of the root, the
radiograph shows us the mistake, keeps us from making a perforation,
and, in many cases, enables us to follow the canal to the true apex. If
the root is unusually short the radiograph keeps us from going through
the apex, and if it is unusually long it keeps us from making the error of
not penetrating the canal far enough. The radiograph shows patients
just what is being done for them.
178
DENTAL RADIOGRAPHY
Fig. 175. The arrow points to a pulp stone in the pulp chamber of an upper second molar.
The blacks and whites in this half-tone are as they appear in the negative, the pulp stone a light
area more or less surrounded by dark.
Fig. 176.
Fig. 177.
Fig. 176. The arrow points to a small pulp stone in the pulp chamber of a lower first molar.
Fig. 177. Pulp stones throughout the canals in the lower central incisors. Also small stones in
the lateral incisors.
THE USES OF THE RADIOGRAPH IN DENTISTRY 179
Having observed quite a large number of radiographs in the last few
years, allow me to state that many, altogether too many in our profession,
fail to enlarge and fill to their apices all canals which really could, and
should, be so treated. There are, perhaps, some cases where the buccal
canals of upper molars and the mesial canals of lower molars simply can-
not be enlarged to their apices. But this fact is no excuse for enlarging
and filling only the upper third of such canals. The stock excuse for
poor canal work is "' our patients will not pay a fee sufficiently large
to enable us to give the necessary time to the work." But do those
who thus excuse themselves really give their patients any choice in
the matter!^ If one should show a patient a radiograph demonstrating tht
fact that he had only penetrated the canals about one-third their length
then explain why he should go farther, and why it would take time to
do so, would the patient say. " Oh ! let 'er go," or would he or she say,
" I v/ant done whatever is best.'' "
It is difficult to radiograph the buccal roots of upper molars, particu-
larly second and third molars.
i3« to Determine lUbetber an Opening Ceading from a Pulp Chamber Be a
Canal or a Perforation.
When one opens the tooth himself, and does not use a small, round
bur on the floor of the pulp chamber, he may feel certain that any open-
ing found must be a canal. But in cases where the pulp chamber has
been opened by another operator, it is often impossible to decide whether
an opening leading from the pulp chamber be the mouth of a canal or a
perforation through the tooth. Likewise in cases where decay has attacked
the walls and floors of the pulp chamber, almost destroying them, it is
sometimes difficult to differentiate between a canal and a perforation.
Pass a wire through the opening and make a radiograph.
A wire passing to the mesial through a perfora
tion in the upper first molar.
Tifl. 174.
14. Tn Cases of Pulp Stones (nodules).
There has been a great deal of dispute as to whether or not pulp
stones can be shown radiographically. The right answer is in the affirm-
ative
The appearance of the pulp stone in the upper
second molar is typical. Though it can be seen
clearly in the print now before me I can only hope
that it will appear in the halftone.
fifl. 175.
l8o
DENTAL RADIOGRAPHY
Tifl, 176.
Case one of neuralgia. The radiograph shows
a pulp stone in the lower first molar at the mouth
of the mesial canal.
Experience in the practice of radiodontia has taught me that there
are many more pulp stones in teeth than I had thought. Indeed I find
myself wondering, after observing great numbers of them which are
not causing pain, if pulp stones ever cause pain. And then I see a case
of neuralgia, or earache, in which the radiograph reveals the presence
of a pulp stone which is removed on suspicion and lo ! the patient gets
well.
178
Fig. 179
Fig. 178.
The arrow points to what might be mistaken for a pulp nodule. The shadow
is, however, a filling on the buccal at the cervical.
Fig. 179. Simple occlusal filling in the molar, encroaching on the pulp.
Considering the common occurrence of pulp stones it is certainly
unwise to remove them whenever found. On the other hand it is some-
times imperative that they be removed in cases of obscure neuralgias
and neuritises.
Intermittent, intense pain in region of chin ex-
Tifl. 177. tending backward to temporo-mandibular articula-
tion. In this case the pulp stones had caused death
of the pulp in the two central incisors. Efforts to remove the stones
from these teeth met with failure and the teeth were extracted. The
pulp stones in the lateral incisors were removed. Result : A cure.
In this radiograph the arrow points to a shadow
TiS. 17$. which was mistaken for a pulp stone. The shadow
is, however, not a pulp stone, it is a small filling on
the buccal surface at the cervical.
Fig. 178 is indistinct, not because the detail of the original negative
has been lost in the process of making the half-tone, as frequently occurs,
but in this case because the original negative was not well made. It was
made many years ago when the art of radiodontia was so young we
scarcely had an idea of what constituted a good radiograph. It is, to
put it mildly, an unnecessary risk to make a diagnosis from a radiograph
as lacking in detail as Fig. 178.
15. Tn Cases of Secondary Dentin Being Deposited and Pinching tbe Pulp
This use was recently suggested in a dental magazine by Dr. Cryer.
Such a condition as the one referred to might exist and be responsible for
neuralgia or other nerve disorders. Likewise it could probably be ob-
THE USES OF THE RADIOGRAPH IN DENTISTRY i8i
served radiographically. At the present time, however, I am unable to
show a radiograph of such a case.
16. Co Cearn if tbe Tilling In the Crown of a Cootb encroaches on tbc Pulp.
Case : Neuralgic pains in the lower left side of
7lfl. 179 face. Thought to be due to a necrotic condition of
the bone in the region of the lower first molar, which
had recently been extracted. A radiograph (Fig. 179) shows the bone
healthy. The simple occlusal filling in the second molar penetrates into
the pulp chamber. This filling was removed, and the semi-vital pulp
devitalized, removed, and the canals filled. The result was an immediate
and complete recovery.
Fig. ISO Fig. 181
Fig. 180. The first bicuspid seems to hold a disto-occlusal filling. This appearance is due
to a slight irregularity — a slight lapping of the teeth. The filling which appears to be in
the distal of the first bicuspid is in the mesial of the second bicuspid. The simple occlusal
filling in the first bicuspid encroaches into the pulp chamber slightly.
Fig. 181. The same as Fig. ISO with the diseased area at the apex of the first bicuspid
outlined, to enable the reader to see it better in Fig. ISO.
17. Tn 0a$c$ of teetb with Carge metal Tillinss or Shell Crowns mhich Do
not Respond to the Cold test, to Eearn if the Canals J\n Tilled.
Case : Slight swelling and pain in the lower
TiflS. l$0 and ISl bicuspid and first molar region. The patient stated
that this condition had occurred and recurred many
times in the past five years. At no time had the swelling been great, and
the pain was never severe. The slight swelling and an annoying pain
would last for a few days, then disappear for a month or so. There was
no discharging sinus. The first molar bore a gold shell crown, the second
bicuspid held a large mesio-occluso-distal amalgam filling, and the first
bicuspid had a small filling of amalgam in the occlusal surface. The
three teeth — the first molar and the two bicuspids — were isolated one at a
l82
DENTAL RADIOGRAPHY
time and tested with cold water. The patient was uncertain as to whether
he received any sensation when the cold was applied to the shell-crowned
molar, but thought that he did. The second bicuspid responded well, and
the first bicuspid did not respond at all. This seemed to indicate a vital
pulp in the molar and second bicuspid, and a devitalized one in the first
bicuspid. But, when looking for a dead pulp, one would naturally sus-
pect either the molar with the shell crown, or the second bicuspid with
the large filling, instead of the first bicuspid with the small occlusal filling
Fig. 182. The roots of the shell crowned first molar are not properly filled. Only the
upper third of the distal canal is filled and the mesial canals are not filled at all. The tooth
was sore and caused annoying neuralgic pains.
The temperature test is a valuable one, but it cannot be depended upon
absolutely. A radiograph (Fig. i8o) was made. It shows the canals of
the molar and second bicuspid unfilled. The tissues at the apices of the
roots of these teeth are healthy, which, together with the positive reaction
to the cold tests indicates that their pulps are vital and healthy. The
simple occlusal filling in the first bicuspid enters the pulp chamber slightly,
the canals of the tooth are unfilled, and the light area at the apex of the
root indicates disease (inflammation) of the bone in that region. These
things, together with the fact that the tooth did not react to the cold test,
indicate a putrescent pulp in the first bicuspid. The tooth was opened,
and the diagnosis confirmed.
In practice, case after case presents, the patient
Tffl. I$2. complaining of a slight soreness or annoying pain in
the region of a shell-crowned tooth, or a tooth with
a large metal filling in it. The tooth fails to respond to the cold test, and
we suspect that the canals are poorly filled, or perhaps not filled at all.
Are we justified in removing the crown or filling to examine the canals?
Before the radiograph came into use we were, but not to-day. It is not
fair to your patient nor yourself to remove a can:il filling unless you can
improve on the operation. Fig. 182 is a radiograph of a case of the
THE USES OF THE RADIOGRAPH IN DENTISTRY 183
class just alluded to. The canal filling in the shell crowned lower, first
molar is so imperfect, it should not be difficult to improve the operation.
Let me give a word of warning, however: Goodness knows it is hard
enough to open canals to the end when you are the one who opens the
tooth for the first time, but, when there has been a previous unsuccessful
effort at canal filling, your difficulties may be multiplied a hundred-fold.
Make no promise of success. Note the slight cervical bone destruction
between first and second molars, due to poorly contoured, poorly fitting
shell crown.
Fig. 183 Fig. 184
Fig. 183. Wire just penetrating the apical foramen. Showing that the apical sensitiveness
is not due to an unremoved, undevitalized remnant of pulpal tissue.
Fig. 184. The wire in the canal of the lateral fails to reach the apex, proving that the
apical sensitiveness is due to an unremoved, undevitalized remnant of pulpal tissue.
1$. Co team if Hpical Smltlwcness Ts Due to a Earge Hplcal Torawen or an
Unremoved, Unaevitalized Kemnant of Pulp.
In the treatment of teeth we often pass the
Tigs. 1$3 and 1$4. broach into the canal until we reach what we know
must be the neighborhood of the apex, when pain is
produced. It is often difficult to decide whether this pain is due to some
remaining vital pulp tissue in the canal, or the penetration of the broach
through the apex. Fig. 183 is from such a case. The wire passing to
the point of sensitiveness goes through the apical foramen, and so proves
that the sensitiveness is not due to unremoved, undevitalized pulp tissue.
In Fig. 184 the wire reaching the point of sensitiveness fails to reach th^
apex, proving that the sensitiveness is caused by an unremoved, unde-
vitalized remnant of pulp.
Let us stop to consider how this question of whether or not we are
penetrating the apex is decided when radiographs are not used. We pump
phenol or some other obtundent into the canal, working our broach farther
1 84
DENTAL RADIOGRAPHY
and farther until we strike the end of the canal ending in a blind alley, or
go so far into the apical tissues we know that no tooth root could be as
long as the distance we are penetrating. The use of the radiograph saves
all this guesswork, obviates the necessity of causing considerable pain and
is a time-saver.
19. Tn €to the eminentia art.icularis B, Fig. 284 of the
same case after reduction. While i^t fails to show the condyle itself clearly,
it shows the neck of the condyle and demonstrates that, in this picture, the
condyle A is on the other side of the eminentia articularis B.
51. Tn Cases of fracture of the Saw-
Fracture of the jaw is almost always accompanied by such a great
deal of swelling and induration that digital and ocular examination
are highly unsatisfactory. The operator who treats a fracture should
know just where and what kind of a fracture he is dealing with. If there
be displacement of the fragments, he must know how much, and in what
direction, the displacement occurs, in order that he may properly readjust
the parts. This knowledge can be gained only by the use of radiographs —
THE USES OF THE RADIOGRAPH IN DENTISTRY 245
Fig. 383. Dislocation of the condyle from the glenoid fossa. A, condyle. B, eminentia
articularis. (Radiograph by Cole and Raper.)
stereoscopic radiographs preferably in cases where there is considerable
displacement of the fragments.
Fracture at the symphysis. The appliance on
»♦ **♦ the teeth is being used as a splint.
Case in the practice of Dr. Cryer. Fig. 286
Tigs, 2$6 and 2$7. shows a fracture of the mandible at the angle. The
body of the jaw is displaced downward. Fig. 287 is
of the same case after reduction and adjustment of an interdental splint.
While the apposition of the fractured ends is not perfect yet, there is a
246
DENTAL RADIOGRAPHY
A a
Wk
J
L
f^^^^^^^^^^i
^^^^^^^Hh^^^^^^^HH^^HHBh^^^. ^ . :
Fig.
284. Same as Fig. 283 after reduction of the dislocation. A, condyle,
articularis. (Radiograph by Cole and Raper.)
B, eminentia
very great improvement over the condition showed in Fig. 386, and I be-
Heve the apposition to be as near perfection as human ingenuity is capable
of carrying it.
Just when to remove a spHnt and bandage from a fracture case is
always a problem. The splint shown in Fig. 287 was removed at the end
of the eighth week. Dr. Loeb, of St. Louis, Mo., states that radiographs
are a great aid in determining just when to remove splints.
fig. 2$8.
A double, comminuted fracture of the mandible
four months after the accident. The bone in the
region of the fracture is necrotic.
THE USES OF THE RADIOGRAPH IN DENTISTRY 247
52. Tn Cases of Jlnkylosis of the Cemporo-manaibular Articulation or tbc
Joint formed by tbc Cootb in tbc law.
The radiograph is of value in cases of ankylosis to observe the cause
of the ankylosis.
Case : A miner who had sustained a traumatism
fig. 2$9. resulting in ankylosis. The ankylosis had existed for
several months at the time Fig. 289 was made. The
dots outline the missing parts, i.e., the anterior border of the ramus and
Fig. 385. Fracture of the mandible at the symphysis. (Radiograph by Blum, of New York City.)
the coronoid process. The disease of the bone could not have failed to
affect the temporal and masseter muscles. It is my belief that in this case
the true muscular tissue was destroyed and replaced with cicatricial tissite,
which condition caused a false ankylosis. I consulted two surgeons, but
neither was able to suggest a corrective operation.
An orthodontist was unable to move a tooth into proper occlusion.
He referred the case to me, thinking perhaps the presence of a super-
numerary tooth body was responsible for the immobility of the tooth. A
radiograph demonstrated the absence of any, such body, and showed that
the tooth had practically no peridental membrane at all. There was a
condition of partial ankylosis, to overcome which it was necessary for the
orthodontist to reinforce his anchorage and exert more force on the re-
fractory tooth. I do not print a radiograph of this case because of the
great difficulty of showing the peridental membrane, or the absence of it,
in a half tone.
§?. Co Observe tbe field of Operation before and after Resection of tbc mandible.
Resection of the mandible is a difficult, radical operation, and one
which has been performed comparatively few times. With the excep-
tion of Dr. Ballin {Items of Interest, June, igo8), operators who have
done this operation have not, so far as I am able to karn, availed them-
248
DENTAL RADIOGRAPHY
Fig. 286. Fracture at the angle of the mandible. Displacement of fractured ends. (Radio-
graph by Pancoast, of Philadelphia.)
Fig. 887. The same as Fig. 286 after reduction and adjustment of an interdental splint.
(Radiograph by Pancoast, of Philadelphia.)
THE USES OF THE RADIOGRAPH IN DENTISTRY 249
Fig. 288. Double comminuted fracture of the mandible. That the reader may understand
the picture, observe the following: A. zygomatic arch; B, sigmoid notch; C, upper part of
ramus; D, one fracture; E, the other fracture; F, fragment of bone between fractures. (Radio-
graph grossly retouched.)
selves of the assistance which good radiographs of the case would have
rendered. Resection of the mandible might become necessary as a re-
sult of an existing pathological condition of the bone, or it might be done
to correct a bad case of prognathism. For whatever reason the operation
may be done, the operation itself is the same, in that a piece of the man-
dible is removed. Consider the operation for prognathism, for example:
A piece of the body of the mandible from each side is cut out and re-
moved. The anterior part is then forced back and the cut ends of the
bone (four of them) wired into apposition. That anti- and post-operative
radiographs of such a case would be of value is apparent.
54. Tn Jill 0a$c$ of facial neuralgia w\ib an Obscure Biology.
Cases of facial neuralgia with an obscure etiology, the exciting cause
for which was disclosed by the radiograph, have already been described
under more specific headings — Figs. 159, 164, 176, 177, 179, 224, 250, 264,
and others. Until the exciting cause is found, when it then receives
a more specific name, any dental pain is likely to be referred to as
npiiralcnn
250 DENTAL RADIOGRAPHY
When making radiographs to learn the cause of trifacial neuralgia,
it is expedient usually to make a large plate picture of the affected side.
This radiograph can then be studied and, if some lesion is discovered,
another radiograph of the particular region of the lesion made on a small
film. The second radiograph, on the film, will be clearer than the one on
the plate, and will verify or disprove the findings in the larger picture.
Fig. 289. The dots outline the missing parts — i.e., the anterior border of the ramus and the
coronoid process. (Radiograph by Cole and Raper.)
Case : Married woman, middle age, suflfered
Tigs. 2^0 and 2^1. from pains in the region of the upper bicuspids. The
dentist could find no lesion that might be responsible
for the trouble. A radiograph (Fig. 290) was made, but does not show
the upper teeth clearly. It does, however, show a shadow in the body of
the mandible in the region of the lozver first molar, which tooth is missing
from the jaw. A radiograph (Fig. 291) of the region in which the
shadow appeared was made on a small film held in the mouth. The film
was not placed in exactly the proper position and, as a result of this mis-
take, pictures only a part of the lesion. It shows the crown of a super-
numerary lower bicuspid with three supernumerary bodies (denticles)
above it. Though the lesion in the lower jaw was not at the location in
which pain occurred, it was very likely responsible for the neuralgia.
THE USES OF THE RADIOGRAPH IN DENTISTRY 251
The patient would not submit to an operation. The case, if not
operated upon, will probably progress to a large dentigerous cystic tumor.
Evidence of this can already be noticed in Fig. 290 by the lack of normal
density of the surrounding bone.
Fig. 290. The arrow points to a shadow in the body of the mandible. (Radiograph by A. M.
Cole, of Indianapolis.)
Case : Married woman, physician's wife, about
Tig. 292. forty-eight years old, had suffered for twenty-five
or thirty years with attacks of neuralgia occurring
four or five times a year, each attack lasting for several days. None save
dental operations were performed, though she received palliative treat-
ment for ear, mastoid cells and antrum trouble. No treatment gave relief.
She left her home in Indiana and spent one winter in South Carolina,
hoping the rnilder climate would ward off the attacks of pain, but this
proved futile. At no time did her temperature rise above normal, prov-
252 DENTAL RADIOGRAPHY
ing, or seeming to prove, that whatever the irritation, there was little or
no suppuration attending it. A radiograph (Fig. 292) was finally made,
and showed an impacted upper third molar. This tooth was removed,
and since then, now over four years ago, she has not had a single attack
of neuralgia.
Attention is called to the fact that up to the time of making the radio-
graph this was a typical case of idiopathic facial neuralgia.
Fig. 291. The same case as Fig. 290. A radiograph of the upper part of "the shadow." It
shows the crown of a supernumerary bicuspid with three denticles above it. The white spot
at the apex of the second bicuspid is caused by an air "bell" attaching itself to the film in that
region at the time it was in the developing solution. (Radiograph by A. M. Cole, of Indianapolis.")
55. to Observe tbe Tnferior Dental GanaK
Often, but not always, we are able to radiograph the inferior dental
canal. (See Fig. 190.) To the man contemplating resection of the in-
ferior dental nerve anywhere throughout its course in this canal a radio-
graph showing the location of the canal would be of value.
Dr. Virgil Loeb, of St. Louis, reports a case of anesthesia of the
lower lip, and that part of the face on one side which receives its nerve
supply from the nerves passing through the mental foramen. The anes-
thesia followed the extraction of a lower third molar. A radiograph of
the case showed that the roots of the third molar had penetrated the in-
ferior dental canal. Knowing this, it was deduced that, at the time of
extraction, the inferior dental nerve had been stretched, and a few fibers
torn at the mental foramen. Lately I have personally observed such a
case. I do not print radiographs of either Dr. Loeb's or my own case,
because they are not clear enough to permit of good half-tone reproduc-
tion. Such cases as the ones now under consideration recover slowly, the
time required varying from one to several months. Treatment with the
high-frequency current may, or mav not. hasten recovery slightly. Though
slow, complete recovery may be expected.
THE USES OE THE RADIOGRAPH IN DENTISTRY 253
Immediately after the filling of the canals of a lower second molar a
patient suffered most severe pain in the region of the filled tooth. A
radiograph was made and showed the canal filling penetrating the apical
foramen of the distal root, projecting into the inferior dental canal, and
Fig. 292. The arrow points to an impacted upper, tliird molar, tlie cause of "idioparliic" neu-
ralgia, from which the patient had suffered recurrently for from between twenty-five to thirty
years. (Radiograph by A. M. Cole, of Indianapolis.)
doubtless pressing the inferior dental nerve. An effort to remove the
canal filling met with failure, and the tooth was extracted to relieve the
patient of the intense pain. Again I do not print radiographs of the case
because the prints are not sufficiently clear to permit of good half-tone
reproductions.
» 56. Tn Cases of Eudwig's Angina.
Angina is defined in Borland's Medical Dictionary as "any disease or
symptom characterized by spasmodic suffocative attacks" ; Ludwig's
angina as "purulent inflammation seated around the submaxillary gland."
Whenever there is a pus sinus opening on the neck in the region of the
submaxillary gland, the patient is said to have Ludwig's angina. This is
the popular application of the term, and it seems to the writer unfor-
254
DENTAL RADIOGRAPHY
Fig. 293. Photograph of a case of so-called Ludwig's angina. Also a radiograph of the case
showing an abscess of the first permanent molar. The fistulous tract cannot be seen.
tunate, for there is seldom angina — i.e., suffocative attacks — in these cases
of suppuration of the neck.
Fig. 293 is a photograph of a case of so-called
Tig. 293. Ludwig's angina occurring in a child ten years of
age. The accompanying radiograph of this case
shows an abscessed lower first molar, which was responsible for the sinus
on the neck. The arrow points to a notch in the lower border of the body
of the mandible. Extraction of the lower first molar and curettement
of the alveoli was all that was necessary to effect a cure in this case. Had
the patient been older, or not so vigorously healthful, the slightly necrotic
area pointed to by the arrow would have required curettement through a
facial opening. The radiograph happens to demonstrate the congenital
absence of a lower second bicuspid.
THE USES OF THE RADIOGRAPH IN DENTISTRY 255
Dr. H. R. Sparrevohn, of Los Angeles, reported a case of "Ludwig's
Angina" in the June number of the Dental Cosmos, 1910. The patient
was receiving hospital treatment for suppuration of the glands of the
neck, when Dr. Sparrevohn examined the case, had radiographs made,
and pronounced the trouble due to an impacted lower third molar, which
could be seen clearly in the radiograph, and in appearance was similar to
Fig. 159, Neither the patient nor the attending physicians could be con-
vinced that his diagnosis was correct. (Had the fistula been injected
with bismuth paste and a radiograph made there would have been no
chance for disoute.) Dr. Sparrevohn closed his report of the case as fol-
lows : 'T should be thankful to readers of the Dental Cosmos if they
would express themselves as to the correctness of my diagnosis. At pres-
ent I am much discredited, especially by the medical men connected with
the case."
Dr. Herbert Mcintosh, a physician, answered Dr. Sparrevohn in
Dental Cosmos, October, 1910. He said in part : "I think there can be
scarcely any doubt that the malposed molar, of which very good radio-
grams were presented, was the cause of the serious symptoms reported.
Anyone who has had experience in the skiagraphing and observing of
such cases would have no hesitation in suspecting dental irritation as the
origin of the symptoms reported in the case. In general, the medical man
is too apt to overlook the reflex irritation produced by the teeth. There
is evident need of skiagraphy to clear up these obscurities of diagnosis in
conditions of the face and cranium. There should likewise be a greater
readiness to admit the importance which teeth have in producing patho-
logical conditions of the tissues."
I believe I am safe in saying that about all of the cases of so-called
Ludwig's angina are due to dental lesions. Yet, referring to no less than
a dozen medical dictionaries and works on the practice of medicine, I
find that none of them even mention the teeth as an etiological factor to
be considered. These books state that the disease is caused by diphtheria,
erysipelas, syphilis, tuberculosis, and that it occurs epidermically and idio-
pathically. It is therefore not surprising that Dr. Sparrevohn's diagnosis
was discredited.
As is indicated by the remarks of Dr. Mcintosh, many medical men
are more enlightened than the authors of the books to which I have re-
ferred. But, on the other hand, many of our brothers in the practice of
general medicine need education along this line. For example, a physi-
cian of my acquaintance, a specialist on the treatment of tuberculosis,
treated, and treated without benefiting, a case quite similar in appearance
to Fig. 293, giving the usual anti-tubercular treatment, including the ad-
ministration of bacterine. The patient's mouth had never been examined
256 DENTAL RADIOGRAPHY
by a dentist, and radiographs of the case were not made, nor were either
of these things done after I suggested them, because the physician thought
it so highly improbable that the teeth could cause such a condition.
To illustrate the grave nature of the symptoms in some of these cases
permit me to report the following case :
Young man, age twenty-three, suffered from what was diagnosed
pharyngeal abscess. Confined to the house for a month, and lost thirty
pounds. A change of physicians brought in a man on the faculty of the
Indiana Dental College. It became necessary to make an external in-
cision to permit the escape of a great quantity of pus. And let me say
that because the incision was made on a line with, instead of at right
angles to, the fibers of the muscle, the resultant scar is hardly noticeable.
The writer was called in consultation. I did not do radiographic work,
nor appreciate its importance at this time, or the doubt in my mind as to
the correctness of my diagnosis might have been eliminated. The patient
could not open the mouth, but instruments passed along the vestibule of
the mouth came in contact with the corner of what I suspected to be an
impacted lower third molar. The mouth was opened, the tooth found
and removed, and the patient recovered immediately. The impacted tooth
was not decayed.
The radiograph should be used in all such cases of suppuration about
the face and neck.
A very large abscess about the apices of the roots
«j of the lower first molar. In facial fistula cases it is
best to make a radiograph which will include the en-
tire side of the jaw. I have seen a case recently where both a lower sec-
ond molar and a first bicuspid were involved in the production of a facial
fistula.
57. Tn €a$e$ of Tnsomnia. neurasthenia, Tnsanity and Kindred nervous Disorders.
If Dr. Henry S. Upson, of Cleveland, were a dentist, his assertion
that dental lesions may, and do, cause insanity, would be met, not alto-
gether unfairly, with the argument that, in the practice of his specialty,
Dr. Upson had developed a rare case of myopia, and could no longer see
past his especial field and consider other etiological factors. But Henry
S. Upson is not Henry S. Upson, dentist; he is Henry S. Upson, M.D.,
Professor of Diseases of the Nervous System at the Western Reserve
University, and Attendant Neurologist to the Lakeside Hospital, Cleve-
land, Ohio.
The situation as it stands to-day is this : Dr. Upson claims that im-
pacted teeth and chronic alveolar abscesses cause insomnia, neurasthenia
and insanity. He gives histories of radiographically illustrated cases,
which have been cured by extraction of the impacted or abscessed teeth,
THE USES OF THE RADIOGRAPH IN DENTISTRY 257
p"ig. 294. Dento-alveolar abscess of the lower first molar discharging on the face.
and he asks a question: "// a diseased uterus can cause insanity (and it
is believed that it can), then why not dental disease?" The nervous con-
nection between the teeth and brain is much more intimate than that be-
tween the uterus and the brain. No one answers Dr. Upson's question,
and so far, no one has in any way tried to prove Dr. Upson wrong in his
belief that the teeth are responsible for grave nervous disorders. We
must then, in fairness, accept what he says as the truth, until we are able
to show wherein he is mistaken.
To give you an idea of the importance of dental lesions as a causa-
258 DENTAL RADIOGRAPHY
tive factor in the neurosis, as promulgated by Dr. Upson, I quote from
the doctor's book, ''Insomnia and Nerve Strain" :
"Of the viscera responsible for the more obscure cases of ne^-vous
and mental derangement, 1 have no hesitation in designating the teeth as
the most important. This is not only on account of the common, almost
universal occurrence of dental diseases, but because these organs move,
during the period of their development, through the solid framework of
the jaw, highly innervated and clothed by a membrane sensitive to im-
pact and to corrosive toxins."
That Dr. Upson has met with skepticism on the part of his brother
practitioners is suggested I believe by the following, quoted again from
the book, "Insomnia and Nerve Strain" :
"There seems to exist among physicians not only a disregard but a
distinct, though mild dislike of the teeth as organs to be reckoned with
medically, they being, as it were, an Ishmael, not to be admitted to their
pathologic birthright. Lauder Brunton's essay on the subject is too little
known and heeded, and few such systematic attempts have been made to
correlate their disorders with the suffering of the human race, except for
the obvious phenomena of pain. Ordinary pain at a distance, as head-
ache or neuralgia, due to the teeth, though well known, is commonly dis-
regarded. Even the various reflex nervous phenomena in children, con-
vulsions, fretfulness, and fever, are not now ascribed to the irritation
either of teething or of dental caries, but to digestive disorders. The
state of recent opinion, as enshrined in epigram, is that 'The result of
teething is nothing but teeth.' "
My readers may ask what has all this to do with dental radiography?
Just this : the radiograph should be used more extensively, as Dr. Upson
has used it, in a search for dental lesions in cases of the various nerve
disorders, for Dr. Upson states "The lesions can seldom be observed by
any means save the use of the X-rays."
Though I would like to print a radiograph and history of all of the
different neuroses including insomnia, neurasthenia, mania, hysteria, mel-
ancholia and dementia, it would hardly be in keeping with a work of this
kind, and I shall therefore give but one case, which is more or less typical.
Case : Melancholia and insomnia. "An unmar-
f Ig, 295. ried woman, twenty-seven years old, a teacher, for
a year had been profoundly melancholy with intract-
able insomnia, delusions of various deadly sins, and entire hopelessness
of recovery. Restlessness was extreme, tonic and local uterine treatment
were of no avail. As a last resort the teeth were examined. They were
apparently in perfect condition. A skiagraph (Fig. 295) showed an im-
pacted upper third molar tooth pressing against the second molar, a con-
THE USES OF THE RADIOGRAPH IN DENTISTRY 259
dition obviously capable of causing irritation. The symptoms, in about
a week after the removal of the tooth, began to improve. Recovery was
complete in six or eight weeks, and has persisted. There had been at no
time pain or other localizing symptoms."
Fig. 295. Impacted upper third molar, causing melancholia and insomnia. (Radiograph by
Lodge, of Cleveland.)
In concluding our consideration of this subject, I quote from a recent
paper by Dr. Upson :
"The following is a tabulated statement of cases of neurasthenia and
the psychoses seen in private practice during about two and a half years,
in which skiagraphic examinations of the teeth and jaws were made.
These results represent the first stumbling efforts in a new and unknown
field, and so do not adequately show what may be accomplished by skill
and careful endeavor along the same line :
Num- Opera- Recov- Conval- Im- Unim- No
lier tion ery escent proved proved Data
Manic depressive type 11 9 5 .. 2 .. 2
Dementia precox 10 8 5 i .. 2 ..
Psychosis 4 4 i 2 .. .. i
Insomnia 7 6 2 .. 4
Neurasthenia 26 15 i 4 6 i 3
58 42 T4 7 12 3 6
The following is a separate statement of the cases of impaction in-
cluded above : -^^^, Opera- Recov- Conval- Tm- Unim- No
ber tion ery escent proved proved Data
Manic depressive type 5 3 2 .. i
Dementia precox 7 5 4 i
Psychosis 2 2 i i
Insomnia 3 2 .. .. 2
Neurasthenia 13 9 .. 4 2 i 2
30
21
26o .
DENTAL RADIOGRAPHY
5$. Tn 0a$e$ of Perioaic l)e(idacbe$.
Irritation of the trifacial nerve may cause headache. The irritation
may be due to such lesions as an impacted tooth, a chronic abscess, or a
cementoma, for examples.
"After the removal of the malposed impacted
Tig. 296. cuspid seen in Fig. 296, severe headaches which she
(the patient) had had once or twice a week for man}'
years ceased immediately."*
Several cases similar to the one cited above have been reported in
recent dental literature.
Fig. 296
Fig. 297
Fig. 296. Malposed impacted lower cuspid, responsible for periodic headaches. (Radiograpli
by Thomas, of Cleveland.)
Fig. 297. An impacted upper cuspid, which caused blinking of the eyes. (.\fter
Dr. Varney Barnes.)
TIfl. 297.
59. Tn €a$e$ of Tacml 6e$ticulatory tic. (Spasmodic twitcMng of a Set
of facial muscles.)
"An impacted upper cuspid which caused blink-
ing of the eyes."**
Dr. Barnes also reported a case of twitching of the facial muscles on
one side. On the corresponding side two supernumerary teeth were
found. I have been unable to learn from Dr. Barnes whether removal of
the supernumerary teeth effected a cure. Dr. Barnes agrees with Dr.
Upson thus far at least : both men are of the opinion that impacted
teeth may be responsible for varied and grave nerve disorders. Dr. Up-
*Dr. Henry S. Upson, Cleveland, Ohio.
**Dr. Varney E. Barnes, Cleveland, Ohio.
THE USES OF THE RADIOGRAPH IN DENTISTRY 261
son's treatment has always been extraction, while Dr. Barnes advocates
orthodontic procedures, such as enlarging the dental arches and elevation
of the impacted tooth.
60, to Jlllay the Tears of a 1>ypochondriac.
Every practitioner of dentistry and medicine has trouble with hypo-
chondriacal patients, patients suffering— and actually suffering— from
some imaginary ailment. What these patients need is psychic treatment.
Fig. 298. The radiograph demonstrates the absence of a piece of the lateral root above the
lateral dummy and shows the canals of the central and cuspid well filled and the tissues at
their apices healthy. (Radiograph grossly retouched.)
To be sympathized with — or a better way to state it would be to say "un-
derstood" — and at the same time shown that their trouble lies, not in any
pathologic lesion, but in faulty habits of thought.
Case : Young lady, age about twenty-three, com-
Tifl. 2$S. plained of obscure indefinite pains in the region of a
bridge extending from central to cuspid, which pains
she declared were due to an unremoved portion of the lateral incisor root.
Having seen the lateral root when it was extracted, and superintended the
treatment of the central and cuspid, and the making of the bridge, and
knowing the patient — in short, knowing the complete history of the case —
I was inclined to believe that the trouble with the bridge lay in the diseased
imagination of the patient. After treating the case with counter-irritants
once or twice, each time conversing freely with the patient concerning her
symptoms, and failing to observe any clinical signs of a pathologic lesion,
I became convinced that my original surmise was correct, and that the
262 DENTAL RADIOGRAPHY
teeth involved in the bridge were causing no pain. I positively knew
there was not a piece of the lateral root above the artificial dummy, as the
patient insisted. Having arrived at this conclusion, 1 proceeded as tact-
fully and kindly as I could to explain my belief to the patient. Where-
upon she broke down and cried, displaying definite symptoms of hysteria.
I want it distinctly understood that I did not blame the patient for
her condition ; that I was not out of patience with her ; that I did not
tell her there was nothing the matter with her — for there was, though the
seat of the trouble was not the bridge. And this I tried to make her un-
derstand. After she had recovered somewhat from her crying, I said :
"Now I do not want to take that bridge off, for I know there is no root
beneath it. I do not need to look and see, as you ask me to. But I know
a way of looking at the bridge so we can botli see it if there is any root
there, or if either of the crowned teeth are at all diseased. If I can show
you beyond the shadow of all doubt that there is no root there, will you
believe that what I have been telling you is perhaps true, that the bridge
is all right, and that you are falling into faulty habits of thought?" She
said she would.
The radiograph (Fig. 298) shows there is no root above the lateral
dummy, that the canals of the central and cuspid are properly filled, and
that the tissues at their apices are not diseased. The radiograph of her
own case, together with several others showing roots above bridges, ab-
scesses and perforations, were shown and explained to the patient. I did
not attempt to force her to admit that I had been right in my diagnosis of
her case, nor did she do so verbally ; but she has not returned for further
treatment, and she still wears the bridge.
61. Tn €asc$ Ulbcrc the Patient Cannot Open tbe moutb lUlde enougb
for an Ocular examination.
An impacted lower third molar sometimes causes a false ankylosis.
We suspect the presence of the impacted tooth, but are unable to demon-
strate it except by the use of the radiograph made extra-orally (Fig.
108). With the radiograph to confirm suspicions and show the exact
location of the offending tooth, the operator may proceed to anesthetize
the patient, force the mouth open with a mouth prop and extract the
tooth.
Fig. 299 is a case in which the mouth could
fifl. 299* not be opened because of the inflammation caused by
the impacted lower third molar seen in the radio-
graph,
THE USES OF THE RADIOGRAPH IN DENTISTRY 263
62. Tn Research Ulork to Study Osteology, the Development of the teetb, Hction of
Bismuth Paste, Bone Production and Destruction, Changes Occurring in the tem-
poro-mandibular Jfrticulation Ulhen lumping the Bite, Blood Supply to Parts, Re-
sorption of Ceeth and the Causes for Tt, etc.
The value of the radiograph to the man who is looking for the just-
how and why of things is clearly apparent. It obviates the necessity of
conjecture, and gives us simple, indisputable facts. Many problems now
Fig. 299. Impacted lower third molar, causing a false ankylosis. (Radiograph by Graham.
of Detroit.)
confronting the dental scientist can be solved only by the intelligent and
persistent use of the X-rays.
It is not my intention now to tell of all the different uses to which
the radiograph has been and may be put in the broad field of dental
scientific research. I could not if I tried. I shall mention but a few.
Dr. Joseph Beck, by the use of the stereoscopic radiographs, is mak-
ing a comparative study of the pneumatic sinuses of man and the lower
animals.
264
DENTAL RADIOGRAPHY
Dr. Johnson Symington and Dr. J. C. Rankin have recently pubHshed
a book, "An Atlas of Skiagrams," illustrating, in twenty radiographs, the
development of the teeth" and jaws from birth to the age of sixteen years.
I have demonstrated the action of bismuth paste in one case. (Fig.
223.) No definite conclusions should be drawn from this single case. The
field of research work along this line is still wide open and inviting in-
vestigation.
Fig. 300. Fig. ;iU1.
Fig. 300. Abscessed upper lateral incisor, causing disintegration of the built-in bone at the
ape.x of the central incisor. (Radiographed by Schamberg, of New York City.)
Fig. oOl. The same as Fig. .300 after treatment and filling of the canal of the lateral. Bone is
being rebuilt into the abscess cavity at the apex of the central. (Radiographed by
Schamberg, of New York City. )
Bone production and destruction in alveolar abscesses is a matter of
which we know entirely too little. A systematic radiographic study of
the subject is bound to result in the disclosure of interesting and im-
portant facts.
A question, the answer to which is of extreme
TiflS. 300 and 301. importance is, "Do alveolar abscess cavities become
filled with bone after the abscess is cured ?"* My ex-
perience leads me to believe they do ; but the new bone may not be quite as
dense, and it is susceptible to ready disintegration as a result of contiguous
inflammation.
Observe Fig. 300, a case from the practice of Dr. R, Otto-
lengui. Note the light areas at the apices of both the central
and lateral. A cursory observation of the radiograph, and a failure
to consider clinical history, would result in the diagnosis of abscess of
both the central and lateral. Observe, please, however, that the canal of
the central is well filled, while the canal of the lateral is not filled at all.
* For a further consideration of this subject see Appendix Chap. XI.
THE USES OF THE RADIOGRAPH IN DENTISTRY 265
5) ^
o i;
g Q
S o
266 DENTAL RADIOGRAPHY
The central had been filled three years previously to the making of the
radiograph, and there had been no recurrence of the abscess during that
time. The lateral was treated and its canal filled, when all symptoms of
abscess disappeared. Fig. 301 was made after the canal of the lateral was
filled. What I shall speak of now I fear cannot be seen in the accompany-
ing half-tone ; but it can be observed easily in the negatives. At the apex
of the central there is a deposition of bone in the old abscess cavity.
The bone is not as dense as the surrounding structure, and hence the out-
line of the old cavity can still be seen ; but it is sufficiently dense, so that
it can be observed distinctly, and especially well when compared with
the cavity at the apex of the lateral, which has not been freed from in-
fection long enough to permit of an osseous formation within it.
Just what changes occur in the temporo-mandibular articulation when
"jumping the bite" is still an unsettled question. It is extremely difficult
to radiograph this articulation, but it can be done, and it is not unreason-
able to expect that some day the radiograph will show us just what occurs.
Dr. H. A. Ketcham, of Denver, is, and has been for some time, working
in this field of research.
Dr. Cryer, in a recent article on the study of blood supply to the jaws
and teeth, printed a radiograph of a disassociated mandible injected with
mercury. How well blood supply may be studied by injecting the vessels
with bismuth paste, or some other substance opaque to the rays, then
making a radiograph is obvious and most encouraging to the student.
The radiographs are of a little girl eleven years
Tifl. 302. of age. They demonstrate the congenital absence oi
the following teeth: In the upper jaw both lateral
incisors, one cuspid and one bicuspid; in the lower jaw three bicuspids,
making in all seven permanent teeth congenitally absent from the jaws.
Despite the absence of the permanent teeth resorption of the roots of the
temporary' teeth occurs, showing that the resorption is not dependent on
the eruption of the permanent teeth. I do not make the statement that
the temporary tooth roots resorb independently of the succedaneous teeth
because of what 1 see in the radiograph in Fig. 302. Fig. 302 but
illustrates what has been observed in many other radiographs.
Dr. H. A. Ketcham, with the aid of radiographs, has endeavored to
disprove that certain orthodontic procedures caused impaction of the
third molars.
The discussion of the orthodontic procedure of
Tigs. 303 and 304. "opening the maxillary suture" is one in which the
radiograph is yet playing an important role. That
THE USES OF THE RADIOGRAPH IN DENTISTRY 267
this suture can be opened is claimed by Dr. Varney C. Barnes. Figs. 303
and 304 are from the practice of Dr. Barnes. How wide it may be opened,
the permanency of the separation of the bones, and the benefits to be
derived from the operation I shall not discuss, but radiography will al-
ways be a valuable aid in determining the condition, both before and after
treatment.
In the discussion of a paper, read at a dental society meeting. Dr.
Fig. 303. Fig. 304.
Fig. 303. Before attempting to open the maxillary suture. (Radiographed by Lodge, of
Cleveland.)
Fig. 304. Same case as Fig. 303 fourteen days later, after attempt to open the maxillary
suture. (Radiographed by Lodge, of Cleveland.")
Don Graham recently said: "If the radiograph has done nothing else it
has proven beyond all doubt that the best canal filling in use to-day is
gutta-percha."
Also radiographs have shown us that, when filling canals with large
apical foramina, we would better force a little gutta-percha through the
apex rather than to fall short of reaching the end of the root. Of the
two mistakes, the former is less likely to be followed by abscess formation.
The radiograph shows an upper cuspid with a
Tig. SOS. perforation to the mesial through the side of the root
into the peridental membrane. The radiograph was
made several weeks after patching the perforation with gutta-percha.
There is scarcely any inflammation at all at the point of perforation.
showing how well the tissues tolerate gutta-percha.
Under this heading of research work allow me to mention the recent
268 DENTAL RADIOGRAPHV
disturbing paper by Dr. William Hunter, of London. Let me say that
Dr. Hunter's charge that we, as a profession, practice septic dentistry is
well founded. One needs to do but little radiographic work to be fully
convinced that the conservative dentistry of which we have been so proud
is often a dreadful mistake. It consists all too often of simply treating
the case until it becomes a chronic abscess, then, with the abatement of
Fig. 305. The arrow points to a perforation, through the side of the cuspid root, which has
been patched with gutta-percha.
the acute symptoms, calling the case cured. As a radiographer, a man in
a position to make extensive observations, I declare that the root canal
work of the majority in our profession is a menace to health. Bad
root canal work is not usually the result of inability to do the work
properly, so let us have hope. It is nearly always due to the fact
that the operator thinks he cannot get paid for the work. And it is indeed
hard to convince a public, which has received its dental education from
advertising quacks, of the necessity of receiving and paying for the proper
treatment of its teeth.
I would not be understood as saying that I agree fully with Dr.
Hunter. I do not. But the doctor is on the right track. He knows there
is such a thing as bad dentistry, septic dentistry, being practiced, as do all
observing men, especially radiographers.
63. m a Record of morK Done.
Any sort of a record of work done is always valuable. Radiographic
records of canal fillings, extractions and the like are often of the utmost
value to the operator. Such records would be of the most gratifying
service in the unpleasant event of being tried for malpractice. A patient,
THE USES OF THE RADIOGRAPH IN DENTISTRY 269
let us say, finds it necessary to go to the hospital for a week after the
extraction of a badly impacted third molar. The next thing the operator
knows is that suit has been brought against him. He learns that he "broke
the jaw-bone," and that the patient is to remain a "helpless invalid for
the balance of her life," because of "his lack of skill, his ignorance and
brutality." Radiographs of the case showing just what had been done
for the patient might prevent the suit or win the case for the operator.
In cases where the patient is seized with a decided disinclination to
pay a dental bill the radiograph may sometimes be used to advantage.
These patients usually suffer from the loss of memory, and tell the judge
that the plaintiff is quite mistaken in imagining that he filled their root
canals. Radiographs would go far toward convincing the judge of the
validity of the claim.
64. Tn eases of 1)idden Dental Caries.
The "diagnosis of hidden dental caries by means of radiographs" was
suggested and recommended by Drs. H. W. C. and C. F. Bodecker in a
short unillustrated paper printed in the Dental Review, April, 1912. I
quote a paragraph from the article referred to. "The diagnosis of caries
in its first stages on the proximal surfaces of molars and bicuspids is
often difficult, and frequently patients complain of sensations at points
where we cannot discover caries either with floss silk or explorer. Sep-
aration then has to be resorted to, in order to definitely locate the trouble.
Sometimes the patient is not able to point out any single tooth in which
he notices the sensation ; he simply tells us that it is 'somewhere on that
side,' and passes the finger over two or three teeth. Another factor
which makes diagnosis difficult is reflex pain. Frequently the irritation
is in an upper tooth, and the patient experiences the pain in a lower one,
and vice versa. Therefore, to obviate the useless separation of teeth in
locating small carious spots, we have used the Roentgen apparatus. It
would, nevertheless, be a useless expenditure of time and work to radio-
graph two or three teeth in the upper arch, and if no defect had been
found to repeat the same in the lower. We have, therefore, constructed
a film holder by the aid of which the crowns of the bicuspids and molars
of one side can be photographed at one time."
Personally, I have never put the radiograph to the use suggested by
the Doctors Bodecker, but it is my intention to do so.
And so — we have passed over the uses of the radiograph in the prac-
tice of modern dentistry, and it has been a long trip. Permit me to repeat
what I said at the beginning of the chapter, for you are now better able
to understand and believe me. Of the uses for the radiograph enu-
merated, some are of cases that the general practitioner of dentistry may
270 DENTAL RADIOGRAPHY
not be called upon to diagnose or treat oftener than once or twice in a
lifetime, perhaps not at all; but by far the greater number are of cases
the like of which we meet almost daily in the practice of dentistry.
There is a popular belief among dentists at large that the use of the
radiograph is indicated only in the baffling, the exceptional, the icono-
clastic cases in our practice. This is not true. It is a fact that the radio-
graph, in a spectacular manner, has been responsible for the diagnosis
and cure of many baffling cases. But I am tempted to^say that this is
unfortunate. For the radiograph does not always solve the mysteries of
the refractory cases, though practitioners of dentistry and medicine pay
it the embarrassing and unfair compliment of expecting it to do so. The
radiograph's most potent value in dentistry is in the ordinary, the every-
day cases which come to our offices — in cases of impacted teeth as an aid
in extraction ; in cases where the apical foramen is very large as an aid
in filling the canals properly ; in cases where apical sensitiveness may be
due to a large apical foramen or an unremoved, undevitalized remnant of
pulpal tissue; in cases of retained temporary teeth to learn if there be
succedaneous teeth present in the jaw ; in cases of badly decayed teeth of
the secondary set in the mouths of children to learn if the roots of the
diseased teeth are fully formed ; in cases of abscess to determine which
tooth is affected; in cases of traumatism, and so on. It is in these cases,
met constantly, that we may use the radiograph and derive the greatest
assistance and benefit. In baffling cases we will often be disappointed in
our use of the radiograph, but in the ordinary cases, such as I have just
enumerated, never, for we know just what to expect, and we do not ex-
pect too much.
It should ever be borne in mind when using the radiograph for diag-
nostic purposes that it is only an aid; in many cases the greatest aid we
have, but, nevertheless, only an aid in diagnosis. No other methods or
means of diagnosis should be forgotten or slighted.
When the use of the radiograph fails to reveal the cause of the
trouble it is not fair to look upon its use as of no assistance or value. For
example, a patient is suffering from false ankylosis. Judging from the
symptoms we suspect an impacted lower third molar to be the active
cause. We make a radiograph and fail to find an offending third molar
or anything else that might be responsible for the ankylosis. It is natural
that we should be disappointed, but we must not feel that the radiograph
has been of no service at all, for we now know that an impacted third
molar is not the cause of the trouble, and we have taken an important
step in diagnosis by elimination.
In printing the great number of radiographs, which have appeared in
this chapter, it is inevitable that some should not be good. It must be
THE USES OF THE RADIOGRAPH IN DENTISTRY 271
remembered, too, that only an idea of what can be seen in negatives can
be learned from half-tones. It has been most discouraging to the writer
to observe, at times, the great loss of detail in the printed half-tones, as
compared to the original negative. However, with the rarest exception
the loss of detail was not the result of incompetency on the part of the
makers of the half-tone plates. This collection of dental radiographs has
Fig. 306. The light area at the apex of the upper first bicuspid has the appearance of an
abscess.
Pig. 307. The same case as Fig. 306, proving the spot at the apex of the upper first bicuspid
in Fig. 306 is not an abscess.
been transferred from the photographic print to the half-tone in a master-
ful way, and its failure to be perfect represents only the shortcoming of
the process itself.
Misinterpretation of radiographs is one of the easiest things in the
world and, for this reason, I can already hear, in imagination, the cries
of condemnation of the disappointed ones who will, within the next few
years, take up dental radiographic work.* I believe that no one who has
ever done radiographic work has experienced disappointment more often,
or more keenly, than I have. But every radiograph ever made is the
product of simple physical and chemical laws, and when misread the
fault usually lies in the reader.
Very often it is expedient to make several radiographs of the same
part, changing the pose slightly to verify or disprove the findings in the
first picture of the part.
Fig. 306 shows what seems to be an abscess at
figs. 306 and 307. the apex of an upper first bicuspid. Fig. 307 is of
the same case and shows no shadow such as is seen
in Fig. 306. The spot in Fig. 306 is not an abscess ; it is a spot produced
by faulty technic in the process of fixing.
Written in 1912.
^72 DENTAL RADIOGRAPHY
When I started this chapter I expected to close it by quoting words
of praise for the radiograph, spoken and written by the leading men in
the dental profession. I shall not take the space to do this, but shall tell
you simply that I could if I wished. I shall quote but one man who, in
an impromptu discussion, voiced the sentiments of all. Though he is a
specialist in oral surgery, he speaks as well for the orthodontist, the ex-
tracting specialist and the general practitioner. Dr. T. W. Brophy said
"Now that we have the X-ray picture to help us, I do not see how we
could possibly get along without it."
The greatest argument in favor of the use and value of the radio-
graph, however, does not lie in the enthusiastic and inspiring remarks
concerning its value, but in the irrefutable facts set forth and illustrated
in this chapter.
Seldom, indeed, is the use of the radiograph in dentistry a matter of
life or death to the patient, though it may sometimes be, but often, often
indeed, does health and happiness depend on its use.*
* In the light of recent discoveries pertaining to metastatic infection due to
local foci of infection in the mouth, it seems that the use of the dental radiograph
IS often a matter of life and death. One needs to see but one case of arthritis
deformans greatly improved or cured, following the eradication of oral foci of
infection, to be tremendously impressed.
CHAPTER VIII.
Che Dangers of tbc X-Kay.
A work of this kind would be worse than incomplete, it would be a
positive menace to the welfare of the public and the profession, without
a chapter devoted to vigorous warning of the evil results that may occur
from exposure to the X-rays.
The following unfortunate results have been attributed to the action
of the X-rays: dermatitis {i.e., X-ray burn), cancer, leukemia, sterility,
abortion, insanity, lassitude and alopecia.
We will now consider each of these foregoing dangers, taking them
up in the order named.
X-ray burns are of two kinds, acute dermatitis and chronic derma-
titis.
Acute dermatitis* manifests itself anywhere
JlCUtC DeimatitiS. from twenty-four hours to (in rare cases) as long as
two or three months after exposure to the rays. The
time, however, is usually from three to fifteen days.
Itching and redness are the first symptoms to appear. The itching
becomes intense, swelling occurs, the skin grows harsh and dry, and has a
smooth, glossy appearance.
In mild cases the inflammation subsides gradually after a few days
and, depending on the severity of the burn, may or may not be followed
by desquamation and loss of hair.
This Elberhart calls an acute dermatitis of the first degree.
In the more severe form of acute dermatitis, termed by Elberhart of
the second degree, there will be the formation of a blister with the usual
serous exudate and marked neuralgic pains.
i^Elberhart "Practical X-Ray Therapy."
273
274 DENTAL RADIOGRAPHY
In the very severe cases of acute dermatitis, where the deeper layers
of the skin and underlying tissues are affected, a slough forms and the
destructive condition shows a marked tendency to spread and become ma-
lignant. Severe pain in these latter cases is a wellnigh constant symptom.
After exposing himself to the X-rays a great
CbtoniC Dermatitis, number of times, and having had a number of mild
attacks of acute dermatitis — or perhaps without ever
Fig. 308. Chronic X-ray Dermatitis.
having had acute dermatitis — the X-ray operator notices certain tissue
changes occurring, usually on the back of the hands, sometimes on the
face and chest. The hands, face and chest are most likely to become af-
fected, because these parts are the most exposed to the rays. There is a
pigmentation of the skin very similar to tanning, such as sun and wind
will produce. Freckles occur in some cases. The skin becomes harsh, dry
and wrinkled — the same changes that occur with age. Hair drops out
The fingernails become brittle and thin and ridged longitudinally. Small,
hard, scabby growths (keratoses) occur here and there. These growths
break down into ulcers, which often become cancerous. (Fig. 308.)
There has been a great deal of discussion as to
Cancer. whether X-rays can, or cannot, produce cancer, but
in the face of such reports as Dr. C. A. Porter's* I
do not see how anyone can dispute it. According to the highest author-
ities. X-rays can, and have, produced carcinoma. In 1907 Dr. Porter re-
* "The Surgical Treatment of X-Ray Carcinoma and Other Severe X-Ray
Lesions, Based Upon an Analysis of Forty-seven Cases."
THE DANGERS OF THE X-RAY 275
ported eleven cases of "unquestionable X-ray cancers," six of which
proved fatal.
Cancer usually follows a chronic dermatitis, occurring at the site of
a former ulcer, though it may result from a very severe acute dermatitis.
When caflcer follows chronic dermatitis the victim is almost invariably
an X-ray operator ; when it follows acute dermatitis the victim is usually
a patient who has been exposed to the rays for therapeutic purposes.
Even before the formation of cancer, when chronic ulcers appear,
operation after operation becomes necessary. These operations consist of
^
Fig. 309. X-ra5' Cancer.
a curettement of the ulcer and skin grafting. With the formation of can-
cer commences amputation. First one finger, then another, then two more,
then a liand, both hands, an arm. A welcome death, due usually to the
formation of metastatic cancers throughout the vital organs of the body,
is the next step of the progressive case.
I print reports here by Dr. Porter of two more or less typical cases
of fatality due to X-ray lesions :
"Case XXXI — Man, 32 years old, who, after three years of X-ray
work, suffered from severe lesions on both arms, breast, neck and face.
In 1901 there began a slowly growing ulceration of the back of the right
hand, which, by the middle of 1902, had become a gangrenous epithelioma ;
glands enlarged at the elbow and in the axilla. Amputation at the shoul-
der ; axillary glands removed, and found full of squamous-celled car-
cinoma. Sound healing. In December, 1904, a typical cancer of the lower
lip and another of the angle of the mouth were excised, as was a suspicious
276
DENTAL RADIOGRAPHY
lesion on the back of the left hand. In March, 1905, a growth of the cheek
was removed, which was pronounced by Unna to be a sarcoma. In Sep-
tember, 1905, excision of the right lower jaw for carcinoma. Recurrence,
involving the tongue and the adjacent cheek, was present in February,
1906. Death soon followed."
"Case XLVII. Summary: In 1897 began work with the X-rays,
testing the tubes for several hours a day. First noticed erythema and
Fig. 310. Hands of X-ray operator after thirty operations.
warty growths in 1900. In 1905, keratoses and warts had formed on both
hands, chest and face. First carcinoma developed and required amputa-
tion of two fingers of the left hand in April, 1907; similar growth curetted
on right hand. By March, 1908, rapid extension of the disease necessi-
tating amputation of left forearm ; curettage of epithelioma on right hand.
August, 1908, involvement of epitrochlear and axillary glands. August
II, 1908, amputation of fingers of right hand. September 25, 1908, ampu-
tation at shoulder. Death on November 7, 1908; general carcinosis." (Fig.
309-)
The report of another case by Porter commences :
"I have operated upon this patient under ether thirty-two times, the
operations varying in duration from one hour and a half to three hours.
At present there remains of his left hand two joints of the little finger,
the forefinger and thumb ; of the right hand, the thumb, the middle finger,
barring part of the terminal phalanx, and one and a half phalanges of the
little finger. More than half of the skin of the backs of both hands con-
sists of Thiersch grafts." (Fig. 310.)
Figs. 308, 309, 310, copied by permission from The Journal of Medical Re-
search.
THE DANGERS OF THE X-RAY 277
Regarding the pain suffered by these patients, with severe chronic
dermatitis and cancer, Porter says : "The amount of pain suffered is
variable though usually extreme. From my experience and personal com-
munications with patients, I believe that the agony of inflamed X-ray
lesions is almost unequaled by any other disease."
Leukemia is a blood disease characterized by an
ECUkcmia. increase in the number of white blood cells. The
cardinal symptoms of the disease are insidious ema-
ciation and lassitude. It is generally fatal. Practically nothing is known
concerning its etiology. It is suspected that continued exposure to the
X-rays may produce leukemia but, as yet, this supposition has not been
scientifically substantiated.
X-ray operators of the male sex, who subject
Sterility. themselves to repeated mild exposures to the rays,
are often sterile. This sterility is due either to the
death of the spermatozoa, or to their complete disappearance from the
semen. This condition has no effect one way or the other on the carnal
instincts of the individual, and if the victim will discontinue exposing the
parts to the X-rays, virility will be regained. Likewise repeated exposures
of the ovaries to the X-rays will produce sterility in the female by causing
a disappearance of the Graafian follicles ; the menses do not cease, and
sexual animation remains unaltered. As with the male, the power of re-
production is regained promptly when the parts are no longer subjected
to X-radiation.
Quoting from Elberhart (Practical X-Ray
Abortion. Therapy) : "Fraenkel claims that the Roentgen ray
retards the growth of the ovum and tends to produce
abortion when the thyroid gland and ovaries are exposed to it."
Fraenkel has in mind the use of the X-rays as a therapeutic agent,
and mentions a case of induced abortion after twenty-five exposures of
five or ten minutes each every other day.
For the slight radiation required for dental radiographic work preg-
nancy cannot possibly be considered a contra-indication.
There is a somewhat popular superstition that
Tn$anity. X-rays will produce insanity in those who constantly
expose themselves to their action. This belief arose,
I think, from the fact that a prominent X-ray operator lost his mind a few
years ago. So far as I know he is the only X-ray operator, of the thou-
sands engaged in the work, who has met with such a misfortune, and it is
as ridiculous to blame the X-rays for it as it would be to claim that his
insanity was caused by the suspenders he wore.
278 DENTAL RADIOGRAPHY
There is a belief among operators themselves that X-ray operators
develop a "nervous, restless, intense personality." Whether the develop-
ment of such a personality is due to the electric condition of the atmos-
phere of the operating room, to the action of the X-rays, or to the enthu-
siastic interest developed by research work is a matter of conjecture. Per-
sonally I do not believe any of these things are responsible for the restless,
nervous personality of so many operators These men were of a restless
disposition before they took up X-ray work. In fact, their adoption of
the work was but a sign of their restlessness and desire to be progressive.
X-ray operators often complain of a feeling of
CassitUdC. utter exhaustion. When it is proven that X-rays can
produce leukemia, I shall believe that this feeling of
extreme lassitude is caused by exposure to the X-rays. Until then I shall
hold to the belief that this exhaustion, which unquestionably does occur,
is due to the work, physical and mental, the bad air of the dark room, and
the depressing disappointments experienced by all conscientious radi-
ographers.
Loss of hair may occur from a severe X-ray
JllOPCCia. burn, but I can find no reliable authority who at-
tempts to prove that the X-rays will produce baldness
of the head without dermatitis.*
Knowing now the dangers of the X-rays, how
Protection. shall we protect ourselves and our patients against
them? We shall protect ourselves by never expos-
ing any part of our bodies to the direct or primary X-rays, and our pa-
tients by exposing them as short a time as possible.
How can we do radiographic M^ork without exposing ourselves to
the X-rays ?
Sheet lead one-eighth inch thick is opaque to very penetrating X-rays.
Lead glass — a transparent glass containing a great deal of lead silicate —
though it would need to be "about two inches thick to totally obstruct very
penetrating X-rays," nevertheless ofifers considerable, and perhaps suf-
ficient, protection in the thickness of one-quarter inch.
The writer was informed that linoleum is opaque to the X-rays. To
test the verity of this information Figs. 311, 312 and 313 were made. A
study of the illustrations will show that, compared to lead or lead glass,
linoleum ofifers very little res'stance to the rays; compared to wood, the
resistance is much greater. White linoleum offers more resistance than
red, green or bine.
* For a further consideration of alopecia see Appendix, Chapter IX.
THE DANGERS OF THE X-RAY
279
Fig. 311. A, B, C, and D are pieces of linoleum. E, a piece of sheet lead l-]6 inch thick.
Appliances for
Protection.
The appliances which may be used for protec-
tion against the X-rays are : Protection lead screens
(Figs. 314 and 315), protection lead cabinets (Figs.
316 and 317), protection shields for the tube (Figs.
60, 61. 63 and 64, Chapter III, and Fig. 318), protection or safety X-ray
tubes (Fig. 319), X-ray proof gloves (Fig. 320), lead glass spectacles
(Fig. 321), and protective aprons.
280
DENTAL RADIOGRAPHY
Fig. 312. A, B, C, and D, same as in Fig. 311. E, a piece of lead glass 1-4 inch tliick.
From the standpoint of protection for the oper-
ChC Ecafl Screen ator nothing is so efficient as the lead screen or cabi-
and Cabinet. net (Figs. 314, 315. 316 and 317). The use of either
makes it possible for the operator to protect himself
completely from all direct X-rays.
The lead used in protective screens and cabinets is usually one-six-
THE DANGERS OF THE X-RAY
281
Fig. 313. A, B, C, and D, same as in Fig! 311. E, the dotted lines outline the position of a
piece of pine wood 1-2 inch thick.
teenth inch thick. Lead of this thickness does not totally obstruct very
penetrating X-rays when the tube is brought close up to it, but at the
usual distance of several feet between tube and screen it is doubtful if
any X-rays penetrate the latter.
The lead glass used in the windows in protection screens and cabinets
is usually one-fourth inch thick. With the tube placed in close proximity
2S2
DENTAL RADIOGRAPHY
Fig. 314.
Fig. 314. Protective lead screen.
Fig. 315. Protective lead screen, sectional vievir.
Fig. 315.
THE DANGERS OF THE X-RAY
283
Fig. 31U. Fig. 317
Fig. 316. Protective lead cabinet; front view.
Fig. 317. Protective lead cabinet; rear view.
to the screen, lead glass of this thickness is highly translucent to the
X-rays, but with the tube a distance of several feet the rays penetrate the
glass but feebly.
Instead of the lead glass window a screen may be covered entirely
with lead and mirrors so arranged that the operator may observe his tube
and patient from his position back of the screen.
Let it be clearlv understood that the man standing behind a lead
284
DENTAL RADIOGRAPHY
Fig. 318. Protective tube shield and stand.
screen is not completely protected from all X-rays. If the tube is rather
close to the screen some of the X-rays may penetrate it — becoming ex-
tremely feeble, however, by the time they make the penetration — and he
is, of course, exposed to the secondary, tertiary and other sets of feeble
rays which fill the room like light. But he is completely protected from
the powerful dangerous rays.
THE DANGERS OF THE X-RAY 285
The protective lead screen, or cabinet, or their equivalent, is a
necessity in the practice of modern radiography.
Protection shields are of three varieties : those
Protection made of lead glass (Figs. 60, 61 and 63, Chapter III),
Shields. those depending on a sheet of metallic lead for their
action (Fig. 64, Chapter 111), and those made of
rubber impregnated with lead or a salt of lead (in appearance similar to
Fig. 64). The X-ray tube fits into the protection shield, which latter pro-
tects the patient to a great extent against the action of all X-rays except
Fig. 319. Protection or safety. X-ray tube.
those which pass through the window of the shield and are being used
to make the radiograph. As a matter of fact, the patient does not need
this protection in the practice of dental radiography, but it is not inex-
pedient to use even protective measures that are thought to be unneces-
sary. The operator is also protected in a degree by the protective shield.
A protection shield calculated to take the place of a lead screen or
cabinet is illustrated in Fig. 318. The protective material used is, I judge
from its appearance, rubber impregnated with lead or a salt of lead. The
manufacturers claim to use a German preparation, the formula of which
is not divulged. This material is more opaque to the X-ray than lead
glass, less opaque than metallic sheet lead.
Protection or safety X-ray tubes are manufac-
ProtectiOtt tured, some of lead glass save for a window of ordi-
X-Ray tubes. nary glass transparent to the X-rays, and some with
an internal protective arrangement which allows the
X-rays to be given out from the tube from a limited place or spot only
(Fig. 319).
286
DENTAL RADIOGRAPHY
The hands of the operator may be protected with
Gloves. X-ray proof gloves. These gloves are usually made
Tig. 320. of rubber impregnated with lead or some salt of lead.
Protective gloves may be made by painting ordinary
leather gloves with several coats of white lead. X-ray proof or "opaque"
gloves, as they are called, are not really opaque to X-rays ; they are, in
fact, quite translucent to powerfully penetrating rays.
Gloves should be used when the operator finds it necessary to hold
the film in the patient's mouth himself. Seldom, very seldom indeed, is
^^•^1 M nifi iaiUi'i
Fig. 320. Fig. 331.
Fig. 320. X-ray proof, opaque, or protection gloves.
Fig. 321. Lead glass spectacles.
it necessary for the operator to do this, and I warn you against the practice
with the same feeling that I would cry "Don't !" if I should see you mak-
ing a plaything of a culture of the bacillus of the white plague.
Protection lead glass spectacles may be used to
Spectacles. protect the eyes (Fig. 321). Not because the eyes
are any more susceptible to the ill effects of the X-
rays than the skin of the face, but because injury to them is such a serious
matter. Operators suffering from chronic dermatitis of the face usually
sufifer also impairment' of vision.
Protection aprons of lead-impregnated rubber
Protection niay be purchased from manufacturers of X-ray sup-
Hpron. plies. They are used to prevent sterility.
Protection gloves, spectacles and aprons are ob-
viously not needed so long as the operator remains behind a screen.
Having now told you of the dangers of the X-
€fficieitcy of I'^ys and shown what measures have been adopted.
Protective measures, to prevent disaster, the question arises, Have these
modern means of protection proved efficient?
So far as I know, no man who has conscientiously and consistently
stayed behind a protective lead screen, or in a lead cabinet, has developed
eithe^- cancer or dermatitis or sterility, or sufifered or experienced any
other pathological change which could be attributed to the X-rays. And
some have been engaged in the work for as long as twelve years.
THE DANGERS OF THE X-RAY 287
The severe and fatal cases of dermatitis and cancer have occurred
in patients who received prolonged and repeated X-ray treatments
for some disease, and in pioneer operators.
As practitioners of dental radiography, we will never be called upon
to make such exposures of our patients as are necessary when the X-rays
are used as a therapeutic agent.
The pioneer operators whose lives were ruined and destroyed by the
X-rays did not protect themselves at all, not knowing that it was neces-
sary. Even without any protection disaster did not manifest itself imme-
diately, as might be imagined. Men worked for months and even years
before any trouble developed. Take the case of a well-known manu-
facturer of X-ray tubes, for example. He exposed himself two or three
hours daily, six days in the week, for a little over a year before he no-
ticed any dermatitis. It must be remembered, however, that at that time
the machines and tubes could not generate near the same number of X-
rays that the improved machines and tubes of to-day can, and the danger,
was therefore less. .
As an example of how efficient even slight protec-
€fficicncy of tion is. Dr. Porter cites a case of dermatitis of the
Slight Protection. hands, save for the skin protected by a broad gold
ring, which remained perfectly normal. The im-
munity which even light clothing offers is shown by the rarity or slight
degrees of dermatitis above the cuffs, or on the other parts of the body
protected by clothing.
Before it was known to be dangerous, operators formed the habit
of using their hands for penetrometers — observing them through the flu-
oroscope to learn the power of penetration of the X-rays. This prac-
tice has doubtless caused many cases of dermatitis and cancer of the back
of the hands. The use of any penetrometer save those of an improved
type which enable the operator to "look around a corner" necessitates the
exposure of the operator, especially his hands, to the rays, and I object
to their use for this reason.
Summarizing the danger to the operator, we may
Summarv ^^^ simply this : If he will observe strictly the rule
Of Danger to remain behind a lead screen or in a lead cabinet
to Operator. he may work for a period of ten or twelve years in
safety. What the dangers of exceeding this time
limit are we do not know. Perhaps there are none. Perhaps all the older
X-ray operators will die of leukemia within the next ten years. Who
can say? We are entitled to our opinions, but no one really know^s. The
pioneers in the work are still in danger ; we who follow are comparatively
safe.
288 DENTAL RADIOGRAPHY
Though the operator need never expose any part of his body to any
except the weak, harmless X-rays which fill the room, it is necessary to
expose at least that part of the patient being radiographed to the direct
rays. The question arises, how long may we expose the patient with
perfect safety, without any danger whatever of producing acute derma- ,
titis ? Authorities are very reluctant to set this time limit.
The very few cases of serious acute dermatitis due to exposure for
radiographic work occurred when the outfits used were so small that the
time for exposures was as long as 20 or 30 minutes. Compare such ex-
posures with those of to-day, which range from a fraction of a second to
only one minute at most, even with the small suitcase outfits, and the im-
probability of producing dermatitis will be appreciated.
The first rule regarding the exposure of patients should be, never ex-
pose the patient longer than absolutely necessary.
And now I shall place myself in line for criti-
CilllC Citllit for cism by authorities, by setting a time limit of ex-
6xpO$ind Patients.* posure of the patient. Even with the smallest appa-
ratus, and where a number of exposures are neces-
sary, the aggregate time of exposure need not and should not exceed two
minutes. If it is necessary to use this full time, two minutes in one day,
then do not expose the same part of the same patient for about 14 to 30
days. Give the skin a chance to recover from any change produced in
it, and so guard against a cumulative efifect of the X-rays. I cannot im-
agine a case in dental radiography which would require an exposure longer
than two minutes. And seldom, indeed, will it be found necessary to
expose the patient, even in the aggregate when several radiographs are
made, as long as the time limit set.
Two minutes is a conservative time limit if the X-ray machine in use
does not force more than about 20 milliamperes through the X-ray tube,
and if the distance between target and skin at the time of exposure is not
less than 16 inches.
It may be truthfully stated that, so far as the patient is concerned,
the application of the X-rays in the practice of radiodontia, is attended
with no danger, if the operator is careful.
"In the early days of the X-rays there was a tendency to attribute X-ray
burns, not to the X-rays themselves, but to some accompanying factor, the
* For a further, more scientific and more comprehensive consideration of the
subject of the exposure of patients to the X-rays see the appendix to Chapter VIII.
THE DANGERS OF THE X-RAY 289
exclusion of which would prevent the occurrence of X-ray burns."* Thus it
was suggested that burns were due to an electrical condition surrounding
the tube ; to chemical conditions surrounding the tube ; to bacteria being
carried into the tissues by the X-rays ; to violet rays, and so on. It is gen-
erally conceded to-day, however, that X-ray burns are the result of a spe-
cific action of the X-rays themselves on the tissues.
Zhi TiltCt, There is a popular theory that for X-rays to
have an efifect on the skin they must be absorbed by
it. Thus, the more penetrating X-rays which pass
completely through the derma are less likely to produce dermatitis than
rays of less penetration — just enough penetration to be absorbed. Know-
ing this theory we will now consider the use of a filter.
First, however, let us dwell on some points which were not touched
upon in Chapter III, when we discussed the generation and nature of
X-rays. It was stated in Chapter III that the X-rays from a tube of high
vacuum were the most penetrating — that the penetration of the X-rays
varied directly according to the degree of vacuum of the tube. Thus the
X-rays from a high vacuum tube are very penetrating, the rays from a
medium vacuum tube of medium penetration, and the rays from a tube
of low vacuum, of low penetration. While this is true, there is something
further to be said. Take the high vacuum tube : while most of the di-
rect X-rays given ofif from it are of high penetration, some rays of me-
dium and low penetration are also generated. While the tube of medium
vacuum generates X-rays of medium penetration principally, some rays
of high and low penetration are also generated ; and though the X-rays
from a tube of low vacuum are by far mostly of low penetration, some few
rays of medium and high penetration are given ofif also.
Since the tube of a high vacuum is the one we use in radiographic
work, let us enumerate the different sets of X-rays given off from such a
tube. First, are the direct rays of high penetration — these are by far
the most numerous ; next, the sets of direct X-rays of medium and low
penetration — these are comparatively few in number ; then secondary X-
rays given off from the glass of the tube ; and last, if there is any in-
verse current in the tube, the rays generated by it.
If now the theory of absorption for effect is correct, then it is de-
sirable to expose the patient only to the direct penetrating X-rays, and not
to any of a less penetrating nature. In an effort to gain this end the
filter is used.
Filters are made of wood, aluminum, leather and various other ma-
terials. For example, a piece of sole leather (no definite thickness) is
*Pusley and Caldwell, "Roentgen Rays in Therapeutics and Diagnosis:
290 DENTAL RADIOGRAPHY
placed over the window of the tube shield. The X-rays from the tube
pass through it before striking the patient and the leather filters out, ab-
sorbs, all ( ?) of the weaker rays, which might otherwise be absorbed by
the skin, and so guards against dermatitis.
The danger of producing dermatitis varies directly according to the
number of X-rays which strike the part. Recollect that X-rays emanate
from a point, traveling in diverging lines. Thus the greater the distance be-
tween the target and the skin the fewer rays strike the latter and the less
danger of dermatitis. When the tube is brought very close (within three
or four inches) to the part and no filter is used the skin is then acted upon
not only by a much greater number of the direct penetrating rays, but also
by the softer direct rays and by the secondary rays from the glass of the
tube, so increasing the danger of burning materially. Thus it will be seen
that the use of the filter permits the operator to place the tube close to the
patient, so that his film or plate is within range of a greater number of
penetrating direct rays, and at the same time protects the patient against
the soft rays.
Theoretically, the use of the filter should aid in obtaining a clear
radiograph by cutting out all save the direct penetrating rays. It is not
as efficient in this respect, however, as the compression cone or cylinder
and diaphragm. (Fig. 65.)
The number of direct X-rays generated by a given tube varies di-
rectly according to the number of milliamperes sent through it. Thus
danger of dermatitis also varies directly according to the number of mil-
liamperes sent through the tube. To elucidate : the distance between the
tube and the skin remaining the same, an exposure of one minute with
ten milliamperes passing through the tube will have practically the same
physiologic efifect as an exposure of two minutes with five milliamperes
passing through the tube.
There is no such thing known as either acquired
Immunity. or natural immunity to the action of the X-rays.
Some are more susceptible than others, but no one
is immune. Blondes are reputed to be more susceptible than brunettes.
One burn greatly predisposes to another.
The careful practitioner of dental radiography.
treatment Of unless he meets a case of idiosyncrasy, will never
Hcute X-Kay have occasion to make use of knowledge regarding
Dermatitis. the treatment of acute X-ray dermatitis. It is well,
however, to have the knowledge even though we are
never called upon to use it. The most important thing to know concern-
ing the treatment of acute X-ray burns may be learned from the nursery
THE DANGERS OF THE X-RAY .291
rhyme about "Little Bo-Peep" and "her sheep.'' ''Eet them alone." So
many drugs aggravate the condition that their use is contraindicated. A
normal salt solution is, perhaps, the best wash and may be used freely.
There will be men in our profession who will not take up radiographic
work, and who will say as an excuse for not doing so that they believe
the work "too dangerous." Men who give this excuse are either unac-
quainted with the facts relative to the real danger or they are deceiving
themselves. A disinclination to do necessary work, mental and physical,
may lead a man to believe that the reason he does not take up X-ray work
is because he believes it to be "dangerous."
It is interesting to know that the rays given off
Radium by the recently discovered element radium are very
Rays. similar to the X-rays.
The commercial, so-called, radium is not pure
radium. It is a salt of radium, usually radium bromid. So far, radium
never has been isolated. Radium bromid is a white crystal.
"In 1896 it was discovered that the metal uranium gave off rays very
similar to X-rays. Observing that different pieces of uranium varied
greatly in their radio-activity, M. and Mme. Curie, of Paris, working on
the hypothesis that uranium itself was not radio-active at all, but derived
this property from some impurity incorporated in it, isolated radium
bromid from the metal uranium."*
At present radium salts are obtained from uranium oxid, which lat-
ter is first obtained from pitchblende, a heavy black material in appearance
somewhat similar to anthracite coal. One ton of pitchblende must be
treated with approximately five tons of various chemicals and fifty tons
of water to obtain one gram of radium bromid. The present markel price
of one gram of radium bromid ranges from $1,500 to $125,000, according
to the radio-activity of the salt.
Radium rays, like X-rays, travel in straight lines, and secondary
rays are given off from objects which they strike. They pene-
trate objects directly according to the density of the object,
ai'xd act on a photographic plate like light and X-rays. Their
physiologic effect on the skin is very similar to X-rays. They pro-
duce a dermatitis almost identical to X-ray dermatitis. Becquerel carried
a sealed glass tube containing 0.2 gram of radium salt in his shirt pocket
for six hours. Fifteen days thereafter a dermatitis closely simulating
X-ray dermatitis appeared, then subsided in about thirty days. One case
of fatality from leukemia caused, presumably, by radium has been re-
ported.
*Tousey, "Medical Electricity and Roentgen Rays."
CHAPTER IX.
Purcbasina a Kadiograpbic Outfit
Before considering the purchase of a radiographic outfit, let us con-
sider the question of who should do dental radiographic work. Should it
he done by specialists or the general practitioners of dentistry ? Six years
ago it was my habit to answer this question unhesitatingly, and say " by
the specialist."
My reasons for believing that dental radiographic work should be
done by specialists were: (i) I was of the opinion that the radiograph
was not particularly useful in the practice of dentistry except in rare
cases, and (2) there being no text-book on the subject, proper self-educa-
tion in the art was difficult, almost to the point of being impossible.
As I see the situation to-day, however, the use of
CbC 0ity the radiograph is indicated in so many cases that it
Practitioner. would be rather impractical for the general practi-
tioner to refer all radiographic cases to the special-
ist, unless said general practitioner of dentistry happened to be located
in a city of sufficient size to support a radiodontist ; not simply a specialist
in radiography, but a specialist in dental radiography. And this would be
practical only if the radiodontist did work at practical fees and could be
depended upon to faithfully fill all appointments. But granting the pres-
ence of such a radiodontist in a city it would be advantageous for the
general practitioner of dentistry to patronize him and thereby give his
patients the benefit of better service than he himself could hope to give.
Also the trained radiodontist is in a position not only to give better serv-
ice, but to give that service at a more reasonable fee.
Each general practitioner who installs an X-ray outfit must, if he
wishes to be fair to himself, charge a fee in proportion to the money, time
and study invested. Suppose now one hundred practitioners install X-
ray machines : The investment in money, time and study — for all of which
the "ultimate consumer," the patient, must pay — becomes tremendous
compared with the investment of a single man, a radiodontist, who could
serve these one hundred dentists. Thus it will be seen that the new spe-
cialist, the radiodontist, has a right to existence, looking at the matter
202
PURCHASING A RADIOGRAPHIC OUTFIT 293
from an economic standpoint. And from the standpoint of service there
can be no fair comparison of the skilled specialist to the general practi-
tioner. A study of Appendix Chapter VI will give some idea of the
treachery of radiographs in the hands of men who do not know their lim-
itations. Fewer radiographs with intelligent interpretations is infinitely
better than many radiographs incorrectly interpreted.
Ihe argument advanced in favor of each dentist
Jlraument doing his own radiographic work is that it is so much
J!gain$t Referring more convenient, for pulp canal work, to have the
Patients. machine accessible and in the same office at all times.
The convenience of having a machine in the office is
indisputable, but the inconvenience of getting it there, and using it in-
telligently after it is there, is likewise indisputable. The dentist who
refers his patients to a radiodontist for canal work should not make it
his practice to place a wire in the canal of a tooth, send the patient to a
specialist, located a mile away perhaps, then wait for the patient to return
with a radiographic report. The patient should be referred to the radio-
dontist between the usual sittings. (A medicinal dressing may be sealed
in the canals with the wires.)
Whether the city man, who has access to a radiodontist should do
at least some of the simpler radiographic work, referring the balance to
the specialist, depends on whether he has the time and enthusiasm neces-
sary to take up the work. Unless he has the time to do it as it should be
done, and unless the nature of the work appeals to him, he had better not
attempt it.
But how about the dentist practicing in a small
Country city or town, who does not have access to a radio-
Practitioner. dontist? The dentists of such a community should
band together and select one of their number to do
radiographic work, buy a good outfit, and refer patients to the man
selected to do the work. In case the dentists of the smaller communities
cannot or will not do this, then each man must have his own X-ray outfit
and do the best he can, just as the country practitioner is compelled to do
the best he can with cases of malformations of the dental arch, difficult
extractions, pyorrhea and other things which he could refer to the spe-
cialist if he were located in a city.
I have said that fewer radiographs with intelligent interpretations
of them is better than a greater number with less intelligent interpreta-
tions. I must add that radiographs and interpretations of any sort are
better than no radiographs at all, and, as I make this statement, I have
not forgotten the perfectly asinine things which may be done as a result
of misinterpretation of radiographs.
294 DENTAL RADIOGRAPHY
For extensive diagnostic examination with the
Specialists' X-rays, requiring the making of many radiographs,
lUorli. some extra-orally, the work should as a rule be done
by a radiodontist, even though it necessitates travel-
ing from town to city on the part of the patient.
The foregoing is a consideration of what I think should be done.
What will actually happen is, I think, that most dentists will install X-
ray machines. The majority will do poor work and will not know it is
poor and so will continue the work, while others who have access to radio-
dontists, seeing their own limitations, will discard their machines. The
country practitioner, even though he detest the work and recognizes his
inability to do it well, will probably be forced to continue it, and so in
time will develop proficiency.
My second reason for having formerly been of the opinion that all
radiographic work should be referred to specialists — viz., the difficulty of
self-education — I hope is no longer a good reason, for I have tried, in this
work, to supply a text-book which will enable the man who wishes to
take up dental radiography to do so without wasting a great deal of time
and energy reading books on electricity, photography and general X-ray
work.
Some manufacturers make such statements re-
ilntrutbfUl garding radiographic work as, "The work is
Statements. extremely simple and can be mastered in a few min-
utes ; in the time it will take to glance over our in-
structions which we send with each outfit." As a result of such misrepre-
sentation men have taken up the work in profound ignorance and so have
endangered their own and their patient's health and life. Self-education
to do the simplest work intelligently, safely and well is not, I assure you,
a matter of a few minutes' study, but of many, many hours.
In passing let me mention X-rays as a therapeu-
X-Kavs as a ^^^ agent in dentistry, and condemn them as useless.
tbetapeutiC It is so difficult to measure the dose in X-radiation
flaent. that it is only by long and usually soul-trying and dis-
astrous experience that a man becomes competent to
use X-rays as a therapeutic agent. The work should be done by special-
ists only. General practitioners of either dentistry or medicine are liable
to do more harm than good when attempting therapeutic X-radiation.
X-rays have been employed in the treatment of pyorrhea alveolaris,
but no results have been obtained that have not been gained by the use
of the easier-used, better-known, less-dangerous drugs, commonly ap-
plied. The incurable cases remain incurable, whether the X-rays are
nsed or not, and, in the cases in which disease is due to local irritants
PURCHASING A RADIOGRAPHIC OUTFIT 295
which can be removed, recovery takes place as a result of the universally
known methods of treatment — again, whether the X-rays are used or
not. X-rays are used also for treatment of cancer of the mouth and
leukoplakia, but such diseases are comparatively rare, and, if treated with
the X-rays, the work should be done by specialists. As far as I know,
this is the extent of the therapeutic application of the X-rays to diseases
of the mouth — an extremely limited application.
In short, my opinion of the value of the X-rays in the practice of
dentistry is this : As a means of making dental radiographs they are in-
valuable ; as a therapeutic agent, they are worse than useless.
Of what should a dental radiographic outfit con-
ReauirementS of ^^^^ ^ Naming the bare necessities for the simplest
an X-Ray work — to which the operator may add, as he does
Outfit. the work and feels the need of expediting apparatus
— we have : ( i ) Photographic paraphernalia and
supplies, including a dark-room lantern, trays, a glass graduate, prepared
developing powder or solution, prepared fixing powder, and films; (2)
an X-ray machine or coil; (3) an X-ray tube; (4) a tube-stand; (5) a
lead screen; (6) a lead. X-ray-proof box for films and plates.
All the photographic paraphernalia and supplies may be purchased
at any photographic or X-ray supply house. The expenditures for pho-
tographic paraphernalia and supplies need not exceed $5.
There are three kinds of X-ray machines for the prospective buyer
to choose from; the transformer or interrupterless coil (Figs. 15 and 38),
the induction coil (Fig. 13), and the high frequency coil (Fig. 14). The
so-called " dental X-ray machines " are either small transformers, me-
dium-sized induction coils or large high-frequency coils.
The transformers are the most powerful and
TtttcrfUptCI*lC$$ most expensive X-ray machines on the market.
Coils. Transformers range in size from the small dental
transformer, selling at about $300 or $400, to the very
large transformers, such as those used by specialists and found in hos-
pitals, selling at over a thousand dollars.
With transformers, intra-oral radiographs may be made in exposures
ranging from a fraction of a second to about 5 seconds ; extra-oral radio-
graphs from a fraction of a second to about 10 seconds.
Transformers operate with equal reliability on either a D. C. or
A. C. circuit. Take two transformers of an equal efficiency, one for a
D. C. circuit and one for an A. C. circuit, however, and the machine for
the D. C. circuit will be a larger, more expensive machine than the one
for the A. C. circuit owing to the difference in construction. (See Fig.
38.)
296 DENTAL RADIOGRAPHY
Induction coils are made in various sizes. The
Induction largest ones rival the transformers in power, the
0OllS. smaller ones are not nearly so powerful. Induction
coils range in price from about $200 to $600.
With induction coils intra-oral radiographs may be made in ex-
posures ranging from a fraction of a second to about 15 or 20 seconds;
extra-oral radiographs from about i or 2 seconds to about 45 seconds.
Induction coils operate at their highest efficiency on the D.C. circuit.
Most high-frequency, suitcase, X-ray coils are
I)l3b-Trcqucncy built to sell ; not to make radiographs. Only the most
tKoilS. powerful of the type are capable of doing good den-
tal radiographic v/ork. I would advise the prospec-
tive purchaser to insist on a practical demonstration before investing.
With high-frequency coils which are strong enough to be used for
dental X-ray work, intra-oral radiographs may be made in from about
3 to 30 seconds ; extra-oral radiographs from about 12 seconds to a length
of time so great that the making of extra-oral radiographs becomes im-
practical.
High-frequency machines operate at their highest efficiency on the
A.C. circuit.
The high-frequency X-ray coils range in price from about $150 to
$200.
A d or 7-inch X-ray tube is the proper size to do
dental radiographic work. The price of the 6 or 7-
X-Ray-tUbC$ \nz\\ tube is well standardized, and is from $20 to
$35- When purchasing a new X-ray tube for dental
work take care not to get one which necessitates vacuum regulation — i. e.,
vacuum reduction — to keep it from backing up 5 inches of parallel spark.
The Coolidge tube costs $125, and necessitates the purchase of a spe-
cial controlling apparatus at a cost of about $200.
There is a great variety of tube-stands to choose
from (Figs. 59, 60 and 61). They range in price
Cube-Stands ^^^^ ^^^ ^^ ^^^^_ ^-^e small tube-stands or holders
which are fastened on to the suitcase coils do not per-
mit of a sufficient range of movement to adjust the tube properly, nor
are they substantial enough to hold the tube firmly immovable.
Lead screens (Figs. 314 and 315) cost from $10
Protection to $30. Even the best lead screens are not backed
Screens with lead thicker than 1-16 inch. The writer oper-
ates back of a "home-made" screen, the lead of
which is yi inch thick, and the 3 x 3 inch window the lead glass of which
is i^ inches thick. The material for this screen cost $15. It is not a
PURCHASING A RADIOGRAPHIC OUTFIT 297
particularly beautiful piece of furniture, and if the time spent in building
it be considered worth anything, I did not save money, but the finished
screen offers more protection than any I know of on the market.
An X-ray-proof box (Fig. 115) may rightfully
A-Kay-rrOOT ^^ considered a necessity; for all photographic films,
plates and paper must be kept in such a box or in
another part of the building away from the lighted X-ray tube. Obviously
it is impractical to keep the photographic films, plates and paper any great
distance from the X-ray apparatus. Hence such a box becomes a neces-
sity. X-ray-proof boxes cost from $5 to $20.
A man may figure from the foregoing approximately what it will
cost him to buy the kind of an outfit he wishes to purchase.
The following is, to the best of the writer's recollection, a complete
list of the manufacturers of X-ray apparatus in America: The Victor
Electric Co., Chicago; the Scheidel- Western X-Ray Coil Co., Chicago;
the American X-Ray Equipment Co., New York City; the Edwards In-
strument Co., Indianapolis ; the Kelly-Koett Mfg. Co., Covington, Ky. ;
the Wm. Meyer Co., Chicago; the Wappler Mfg. Co., New York City;
the Kny-Scheerer Co., New York City ; the Campbell Electric Co., Lynn,
Mass. ; the Vulcan Coil Co., Los Angeles ; the H. G. Fischer & Co., Chi-
cago ; Noyes Bros. & Cutler, Inc., St. Paul ; Geo. W. Brady & Co., plate
manufacturers, Chicago; Roentgen Mfg. Co., Philadelphia; Green &
Bauer Tube Co., Hartford, Conn. ; MacAlaster-Wiggins Tube Co., Chi-
cago ; Machlett & Son, tube manufacturers, Chicago ; Mcintosh Battery
& Optical Co., Chicago ; Kesselring X-Ray Tube Co., Chicago ; the Rogers
Electric Laboratories Co., Cleveland, Ohio ; the Eastman Kodak Co.,
Rochester, N. Y. ; the Cramer Dry Plate Co., St. Louis, Mo. ; Snook
Roentgen Mfg. Co., Philadelphia, Pa.; Waite & Bartlett Co., New York
Citv; Columbia X-Ray & Electric Corporation, New York C\\^.
CHAPTER X.
Stereoscopic Kadiograpby.
The word stereoscopic is derived from two Greek words, meaning
'solid" and "to see."
Fig. 322. Hand stereoscope in u.se.
The phenomenon of the stereoscopic picture or radiograph is one
very difficult to explain briefly. It is sufficient for us to say here that to
gain a stereoscopic effect — that is, to get a picture rich in perspective —
we must have two pictures, one for each eye, and observe them with a
stereoscope (Figs. 322 and 323). When the two pictures are properly
focused in the stereoscope, the observer no longer sees two flat pictures
of the same object, but, instead, the single object stands out in clear
perspective, just as it would if we looked at the object itself, the two
pictures being registered on the retina of either eye and the merging centre
of the brain fusing them into one.
298
STEREOSCOPIC RADIOGRAPHY
299
To make stereophotographs it is necessary to use a special, double-
lens camera (Fig. 324), which takes a picture for each eye simultaneously.
Figs. 337 and 338 are stereophotographs.
A moment's consideration of the subject makes it obvious that two
radiographs, one for each eye, cannot be made simultaneously. We must
Fig. 323. Large stereoscope made especially for observing stereoradiographs
place the X-ray tube in the position to make the radiograph for one eye
and make the exposure, then shift the tube two and one-half inches (the
approximate distance between the eyes), place a new plate or film in
exactly the same position occupied by the first plate or film (and this
without changing the position of the part being radiographed), and make
a second exposure to get the radiograph for the other eye.
To accomplish the proper shifting of the tube a
Stereoscopic special tube stand or pedestal should be used. There
Cube Stand. are several such stands on the market known as
"stereoscopic tube stands." The one shown in Fig.
61, and again in Figs. 326 and 330, is used by the writer.
300
DENTAL RADIOGRAPHY
To accomplish the removal of the first plate
PIjiI^ after exposure, and replace it with a second plate
0b(ingci*$. for the second radiograph, without changing the
position of the part being radiographed, it is neces-
sary to use a plate changer (Fig. 325), or a "stereoscopic table" (Fig.
Fig. 324. Double lens camera for making stereophotographs.
Fig. 325. Piatt changer.
326), which latter is simply a large plate changer made into a table. The
principle of all plate changers is the same. The part being radiographed
rests undisturbed on a window of celluloid or thin aluminum, while the
plates slide beneath in a tunnel.
STEREOSCOPIC RADIOGRAPHY
."^oi
.^^"*^**^
)T
Fig. 326. Stereoscopic table and tube stand. H, centering rod.
The plate changer illustrated in Fig. 330, and explained by diagram in
Fig. 327, differs from others in that only one five by seven inch plate
is used, two pictures, five by three and one-half inches, being made on
either end of the plate. A five by seven stereoradiograph (both pictures
on the one plate) may be observed with a hand stereoscope (Fig. 322),
while all other plate stereoradiographs must be observed with the special
stereoscope (Fig. 323).
3C2
DENTAL RADIOGRAPHY
I J
Fig. 327. A and AA, lead which protects the plate against the action of the X-ray. B, window
of thin aluminum or celluloid on which the part being radiographed lies. C, end of the tunnel.
D, plate carrier. E, end of 5x7 plate on which the first radiograph is made with the tube in
position I. EE, end of plate on which second radiograph is made after it is shifted under
the window B, and the tube is in position J. F, centering line. G, angle of X-rays with the
tube in the first position, I. H, angle of X-rays with the tube in second position, J.
The diagram shows the tube being shifted on a line with its long axis. It may be shifted in
this manner, or at any angle to its long axis — it makes no difference.
Fig. .328. Compression cones, cylinder and square, and diaphragms for same.
STEREOSCOPIC RADIOGRAPHY 303
tecbnic for makins Stercoradiograpbs.
Let us now take a concrete example and describe and discuss the
steps taken in the making of Fig. 339.
First, what should be the distance between the
Distance. target and the plate? There are no special rules to
follow regulating the distance between the target and
the plate when making stereoradiographs. The same results were ob-
tained by the writer with the distance twelve inches as when working
at twenty-four inches.
Fig. 329. The lead glass bowl and X-ray tube must be removed while the centering rod is
being used. When the stand is "set," the rod is removed and the protection bowl and X-ray
tube replaced.
The first step is to "centre the tube," to place it
Setting so that a line (line F of Fig. 327) drawn from the
Cube Stand. focal point on the target will strike the plate in the
center. This may be done with the greatest accuracy
by the use of the centering rod (Fig. 326), but the use of the rod is
not imperative unless a compression cone or cylinder (Fig. 328) is to be
used, as will be described presently.
After centering the tube, when using a stand like the one in Figs.
326 and 330, the stand is "set" so that the tube may be moved one and
one-quarter inch on each side of the center to positions I and J of
Fig. 327 (see illustration).
304
DENTAL RADIOGRAPHY
Fig. 330. Pose for making Fig. 344. It is often expedient to have the patient remove the
coat and collar for this pose.
STEREOSCOPIC RADIOGRAPHY
305
wmmmmmmmmmmmmmmmm^
Fig. 331. Modified Kny-Sheerer film holder.
Fig. 333. The film holder shown in Fig. 331 in position.
Fig. 333. Another view of the film holder in positic
3o6
DENTAL RADIOGRAPHY
. It is not necessary to tip the tube, as it is shifted,
tipping in order to have the X-rays strike the object and
tI)C Cube. plate at the proper angles — at the angles at which the
eyes of an observer would see the object, because the
X-rays emanate from the focal point on the target in diverging lines in all
directions. So the same X-rays are not used to make the second picture
that are used to make the first. If they were, it would be necessary to
tip the tube to make them strike the object and the plate at the proper
angles. (Observe lines G and H of Fig. 327,) When using a compres-
Fig. 334 Fig. 335 Fig. 336
Fig. 334. The photographic print from which this halftone was taken was made from the
original negative, or "first picture."
Fig. 335. The same as Fig. 334, except made from "pictures one and two," held together
with binding strips.
Fig. 336. The same field as Fig. 334, but made from the "third picture."
sion cone or cylinder we do use the same rays tO' make both radiographs,
and hence it becomes necessary to tip the tube as it is shifted. This can
be accomplished with accuracy only by the use of the centering rod (see
Fig. 329). Thus, if a cone or cylinder is to be used, the tube stand must
be "set" not only to shift the tube but to tip it also as it is shifted.
With the tube stand "set," the tube in position I of Fig. 327, and the
plate in the position shown in Fig. 327, the first exposure is made. The
tube is then shifted to position J, the plate carrier pushed in until the
unexposed half of the plate comes under the window B, and the second
exposure is made. Since the two radiographs are made on the same plate
in this instance, special care should be taken to expose them each the
same length of time. Otherwise they will "come up" unequally in the
developing solution and radiographs of different densities will result.
If the technic outlined above is followed, it will be found when
observing the finished stereoradiograph that we see the part from
the position of the tube during exposure. Thus observe Fig. 339, which
was taken with the palm of the hand toward the plate, a coin on the
back of the hand, a needle under the hand.
If, instead of following the technic as given, the first exposure be
made with the tube in position J and the plate as shown in Fig. 327,
and the second exposure with the tube in position I', after the plate is
shifted; then, when observing the finished stereoradiograph, it is as
STEREOSCOPIC RADIOGRAPHY
307
Fig. 337. Stcix-oiihotograiih of the skull of a monkey, frc
skulls of vertebrates.
Dr. John J, Kyle's collection of
though we saw the part from the position of the plate during its
exposure (see Fig. 340).
This changing of position of observation may be accomplished also
by interchanging the two radiographs — placing the right on the left and
the left on the right. Take Fig. 339, for example ; interchange the radio-
graphs and the stereoradiograph is the same as Fig. 340; or take Fig.
340 and interchange the radiographs and the stereoradiograph is the same
as Fig. 339. The interchanging of radiographs must be done without
inverting them, or the change of position of observation will not be ac-
complished — the stereoscopic effect will remain the same and the part will
simply be viewed upside down.
Fig. 338.
Sagittal section of the skull of a monkey, from Dr. John J.
skulls of vertebrates.
Kyle's collection of
308
DENTAL RADIOGRAPHY
Fig. 339. Showing tlie coin on one side of tlie hand, the needle on the other, ilere we ob-
serve the hand from the position of the tube.
Fig. 340. The same as Fig. 339 except that we observe the hand from the position of the plate
during its exposure, instead of the position of the X-ray tube.
STEREOSCOPIC RADIOGRAFHY
309
Fig. 341. Three nails of the same size and length. One is in a vertical position, the other
two lean toward the observer, at different angles.
Figs. 341, 342 and 343 are the same radiographs mounted differently.
No stereoscopic effect at all is seen in Fig. 343, because the tube was
shifted at right angles to the long axis of the nails. Had the tube been
shifted on a line with the long axis of the nails it would l:ie necessary to
observe them as in Fig. 343 to get a stereoscopic effect.
Fig. 342. The same as Fig. 341 except that the individual radiographs are interchanged, the
right changed to the left sid'e and the left to the right side. Thus in this stereoradiograph
the leaning nails lean away from instead of toward the observer.
310
DENTAL RADIOGRAPHY
Fig. 343. Xo stereoscopic effect at all is obtained with the radiographs mounted as in this figure.
Special Cecbnic
for Dental Stereo-
Radlograpby.
\Y& now come to a more definite consideration
of dental stereoscopic radiography. Stereoradio-
graphs of the lower teeth may be made on plates
using the plate changer illustrated in Fig. 327. Fig.
344 is such a stereoradiograph. Fig. 344 was made
from the pose illustrated in Fig. 330.
Fig. 341. Though the stereoscopic effect is not very good the' figure is representative of what
can be done by the method employed to make this stereoradiograph.
STEREOSCOPIC RADIOGRAPHY 311
When making stereoradiographs on separate plates, like Figs. 345
and 346, it is necessary to use a large plate changer, like Figs. 325 and 326.
Figs. 345 and 346 were made on eight by ten inch plates, and the radio-
graphs reduced, as shown in the figures, so that they might be observed
with the small hand stereoscope. To observe the original negatives it is
necessary to use a large stereoscope (Fig. 323).
When making dental stereoradiographs, on films
Dental Tllm held in the mouth during their exposure, the problem
l)Older. of replacing the first film, after its exposure, with a
second film, which will occupy precisely the same
position as the first, is one fraught with great difficulties. In an effort
to accomplish this the writer uses a Kny-Sheerer film holder and model-
ing composition. The film holder, as I use it, is modified almost beyond
recognition (see Figs. 331, 332 and 333). Films may be placed in this
modified holder in exactly the same position, and, by the aid of the im-
pression of the occlusal surfaces of the teeth in modeling composition,
the holder may be replaced in the mouth in the same position. This film
holder is applicable to practically any part of the mouth, but especially
so to the molar region.
It is not absolutely necessary, but I prefer to have the patients pose
in a recumbent position for all dental stereoscopic work, believing they are
less likely to move the head while the films are being changed in this
position than they would be if sitting in a chair. Thus the pose for
making Fig. 347 was a slight modification only of Fig. 330.
Thanks to the work of Dr. C. Edmund Kells, we now know that it
is not necessary to have the two films in exactly the same position to make
a stereoradiograph like Fig. 348. All that is necessary is to have them
occupy exactly the same plane. Hence no film holder need be used. The
film is placed in the month as in Figs. 95, 96 and 103.
After the two film negatives are made, prints
PrevaratiOll of "^^^ ^^ made from them, and these prints mounted on
KadioarapbS for cardboard to be observed with the hand stereoscope.
Study Witb stereoscope. Or the negatives themselves may be observed stereo-
scopically by mounting them on transparent glass,
sticking them in place with binding strips such as are used in passe par-
tout work.
The distance between the radiographs mounted for stereoscopic ob-
servation should be approximately two and one-half inches from a given
point in one radiograph to the same point in the other radiograph. Great
312
DENTAL RADIOGRAPHY
Fig. 345. Antero-posterior view of a dry skull. The right sphenoid sinus is filled with lead shot
accuracy in mounting the radiographs for stereoscopic study is not
necessary though preferable.
It is always . expedient when making dental
CandnttirkS. stereoradiographs to place some landmark, such as
an anchor clamp band or a wire, on the teeth. Know-
ing then that the screw and nut of the clamp band are on the lingual or
buccal side, as the case may be, or that the wire is twisted on the lingual
or labial side, as the case might be, we may determine immediately, when
Fig. 346. The reproduction here has lost much of its excellence. When the original negatives
were viewed in the illuminating stereoscope, one could look as clearly and directly into the skull
as -he could into a soap bubble. The dark outline is the antrum nearer the observer filled with
lead shot. (Stereoradiograph by A. M. Cole and Raper.)
STEREOSCOPIC RADIOGRAPHY
313
observing the stereoradiograph, whether we observe the part from the
position of the tube or the position of the film.
Dr. Kells states that, as a general proposition, a more perfect stereo-
scopic effect may be gained if the radiographs are mounted so that the
stereoradiograph is observed from the position of the film. This is true,
and one reason for it is that, other things being equal, the closer an object
Fig. 347. Impacted lower, left, third molar, viewed from the lingual,
the clamp band are on the lingnal.
The screw and nut of
Fig. 348. Viewed from the position of the film — from the lingual. The temporary cuspid is
so much decayed and resorbed it can scarcely be seen. The wire around its neck can be seen
clearly. The wire is twisted on the labial.
is to the plate or film the clearer it is outlined in the radiograph. Like-
wise as we look upon a scene, the closer objects are clearer than those at
a distance. Hence, when we observe a stereoradiograph from the position
of the film or plate during its exposure, those parts of the stereoradio-
graph seeming to be closer to us are clearer, while those farther away are
less clear.
If the film packets used contain two films each, four negatives will
be made, and these may be mounted on clear glass, so that the operator
314
DENTAL RADIOGRAPHY
may observe the part from the position of the film and tube also.
In direct proportion as things are large or small
it is easy or difficult to discern perspective. The
parts in dental radiographs are so small that it is
difficult to gain perspective. In an effort to over-
come this handicap, to an extent at least, Fig. 350
was made. Fig. 350 is an enlargement of Fig. 349. Owing to the loss of
enlarsement
of Dental
Stcreoradiograpbs.
Fig. 345'. Impacted upper, third molar, viewed from the position of the tube. The wire pass-
ing around the neck of the second molar is twisted on the lingual. The impacted tooth sets
to the buccal.
Fig. 350. Same as Fig. 349 enlarged.
detail incident to enlargement there seems little if any advantage in this
step. There is none made at the present time, but a magnifying stereo-
scope would probably be of value for viewing dental stereoradiographs.
So much for the technic involved in the practice
Practical Ualue °^ dental stereoscopic radiography. Let us now con-
Of Dental Stereo- sider the results, the practical application and the
radioarapbl. possibilities of dental stereoscopic radiography.
Frankly, the results are discouraging. Considering
STEREOSCOPIC RADIOGRAPHY
315
the difficulties of practice, and the results obtained at the present time,
there is an extremely limited practical application of the stereoradiograph
to dentistry. What the future possibilities of dental stereoscopic radiog-
raphy are I would not attempt to say. My hope is that some day we
may be able to stereoradiograph the upper molar roots successfully.
By describing it I think I have proved that the technic involved to
do dental stereoscopic work is so difficult that the work should be left
entirely to specialists in radiography. Even in the hands of the most
skillful it seems, at the present time, that there are several good reasons
why it will never be popular. The reasons are: (i) The difficulty, and
Fig. 351. Coins at different distances from a wire screen.
at the same time the necessity, of obtaining two radiographs uniformly
rich in detail. (2) The difficulty and necessity of placing two films in
the mouth in the same position. (3) The difficulty and necessity of having
the patient maintain the same pose while the two exposures are made.
(4) The great amount of time consumed to do the work. (5) The parts
being so small makes it especially difficult to gain a stereoscopic — a per-
spective — effect. (6) One of the most important reasons why dental
stereoscopic work probably never will be popular, even among specialists,
is that we feel no great need of it. The single radiograph is not totally
lacking in perspective, and a careful study of it will reveal almost, if not
quite, as much as can be seen in the dental stereoradiograph. (7) The
stereoradiograph is sometimes misleading. For example, see Fig. 351.
To make this illustration three coins were placed on a piece of wire
screening, one directly against the screen, the other two resting on cotton
3i6
DENTAL RADIOGRAPHY
built up to hold them at different distances from the screen. In the
stereoradiograph the coin which rests against the screen seems to stand
out from it a short distance.
Some day perhaps we may so modify and perfect our technic that
the stereoradiograph will be of indispensable value (i) in observing the
three roots of upper molars; (2) in seeing a wire passing through a
perforation to the labial, buccal or lingual; (3) in some particular cases
Fig. 352. Same as Fig. 339 made "plastic.
of impacted teeth to show more exactly their location, and so aid in the
extraction; (4) in showing the orthodontist when he may move the com-
ing permanent teeth by moving the deciduous teeth; (5) in determining
more exactly than can be done with the single radiograph the size and
location of a pus cavity or cyst; (6) in cases of fracture of the mandible;
(7) in locating exactly bone "whorls," calculi in the glands or ducts of
glands and foreign bodies in the antrum; (8) in learning the size, shape
and location of the antrum as an aid in opening into it ; and (9) in cases
of tumor to locate more definitely the offending body.
STEREOSCOPIC RADIOGRAPHY
317
Plastic KadiograDby.
There is no one thing which so Hmits the usefulness of the radio-
graph as its lack of good perspective. Hence our interest in stereoscopic
radiography. Hence, also, our interest in plastic radiography.
Plastic radiography is a method of making radiographs in such a
way that the parts stand out in has relief. A better name than plastic
1
s _.
Fig. 353. Plastic reproduction of Fig. 34';
Fig. 354. Fig. 353 enlarged.
radiography would have been trick radiography. I describe the method
simply as a matter of interest. It is of no practical value whatever.
The following are the steps in making a plastic
CcchniC Of radiograph. The negative is made as usual. For
Plastic convenience in referring to it we shall call the nega-
RadiOflfapby. tive the first picture. From the first picture another
picture, the second picture, is made on a photographic
plate, the technic for doing this being the same as for making con-
tact lantern slides. The first and second pictures are now placed to-
gether, non-sensitive sides in apposition, held up to the light and moved
about until the parts of the two pictures overlie one another exactly. They
are now held immovable while an assistant sticks them together with
3i8 DENTAL RADIOGRAPHY
paper binding strips. Next, place them in a printing frame and make a
photographic print on paper (see Figs. 335. 352, 353 and 354). While
the exposure is being made the printing frame must remain immobile
and the light must pass through pictures number one and number two and
strike the photographic paper at an angle of about ninety degrees.
Instead of allowing the light to pass through pictures one and
two and strike the photographic paper at an angle, the same result
may be accomplished by allowing the light to pass straight through pic-
tures one and two, if at the time they are stuck together the two pictures
are almost, but not quite, in perfect overlying opposition.
Instead of making the print on paper from pictures one and two,
another picture, number three, may be made on a plate, and from this
third picture photographic prints made (Fig. 336).
Plastic radiography is simply a scheme of shading radiographs
Nothing more can possibly be seen in the plastic production than could
have been seen in the original negative, though, perhaps, something may
be seen more easily. To the man unacquainted with the reading of radio-
graphs the plastic pictures seem much clearer, but to the man of experi-
ence it is not so clear, for there is an unavoidable loss of detail in the
making of the plastic reproduction.
Figs. 352, 353 and 354 are plastic stereoradio-
PlastiC graphs. It is interesting to pause and consider the
Stcreoradioai'apbS* number of steps necessary to make Fig. 354. First.
the negatives were made ; from these the "second
picture" of the plastic method, then the prints on photographic paper,
from which enlargements were made, and then the halftone.
In concluding let me say that the properly made, intelligently
read single radiographic negative is of the utmost importance and value
in the practice of dentistry. Let us not forget this, and let us not decry
the radiograph because our efforts in stereoscopic and plastic work fail to
make it absolutely infallible.
* For a further consideration of dental stereoscopic radiography see Appendix,
Chapter X.
APPENDIX
APPENDIX TO CHAPTER I
Electricity
To make the meaning of the word " phase," used as an electrical term,
clear, would require the use of unnecessary space in this volume.
The operator need not bother about the phase of his supply currrent.
As it readies him it is single phase and X-ray machines are always built
for the single phase current.
•;tq
320
APPENDIX
APPENDIX TO CHAPTER II
X Ray machines
Some eight or ten special dental X-ray machines have been placed
on the market within the past three years. The machines represent, in
Figure 355A. — Special dental X-ray machine. Transformer or Interrupterless type. Size: 24
inches wide, 20 inches deep, 59 inches high.
their construction, the three standard types of X-ray machines, viz., the
transformer, or interrupterless coil, the induction coil and the high-fre-
quency coil.
X-RAY MACHINES
321
Figure 355B. — Special dental X-ray machine. Transformer or Interrupterless type. Size: 17
inches wide, 23 inches deep, 37 inclies high.
Figures 355, A and B, and 356 are representative of the dental trans-
former type.
Figures 357 and 358 are representative of the dental induction coil
type. The tube on top of Fig. 357 is a valve tube.
322
APPENDIX
Figure 359 is a dental X-ray machine of the high-frequency coil type.
With some types of the high-frequency X-ray coil (Fig. 360) the
operator has at his disposal the high-frequency current for electro-
therapeutic work.
The value of the high-frequency current as a therapeutic agent in the
practice of dentistry has not been satisfactorily established. I would
Figure 356. — Special dental X-ray machine,
electrotherapeutic — attachment on the top.
high.
Transformer type, with high-frequency — i. e..
Size: 21 inches wide, 20 inches deep, 71 inches
suggest, however, that the man with such a current at his disposal might
experiment with it using it with the idea that it is a cellular massage.
Some coils are so constructed that the coil proper may be placed on
a shelf on the wall, up out of the way, the controls of the coils or switch-
board being mounted elsewhere and within easy reach. With an X-ray
machine installed in this way " overhead wiring " is usually necessary
The principle of the overhead wiring system is illustrated in Fig. 361.
The terminals of the coil are attached to the overhead wires. On the
X-RAY MACHINES
323
Figure 357.— Special dental X-ray machine. Induction coil type. Size: 15 inclies wide, 23
inches deep, 30 inches high.
overhead wires are the trolley reels which fasten to the tube. The con-
venience of overhead wiring is great.
It will be observed that on Fig. 362 there are the usual terminals, viz.,
the positive and negative secondary terminals and the " dead " or " false "
324
APPENDIX
Figure 358. — Special dental X-ray machine. Induction coil type. Size: 30 inches wide, 17
inches deep, 44 inches high.
terminal to which the vacuum reducing lever is attached. Back of these
terminals are two others. It is interesting to know what these two extra
terminals are for.
They are connected directly to the terminals of the secondary winding
X-RAY MACHINES
325
Figure 359. — Special dental X-ray machine. High-frequency coil type. Size: 24 inches wide,
10 inches deep, 52 inches high.
of the transformer before rectification, so that the current dehvered at
these two terminals is high potential alternating.
In addition to the safety valve action, they have two other functions.
One is to indicate when the disc switch is out of synchronism. While
the current " slopping " across these two terminals occasionally, would not
indicate anything wrong with the switch, if the current slops across reg-
326
APPENDIX
ularly and in considerable quantity, it is a certain indication that the disc
has gotten out of synchronism.
The remaining, function is to deliver unrectified alternating current
to a high-frequency attachment, should the user of the transformer desire
to operate a high-frequency apparatus in connection with the transformer.
(Fig. 356.)
Figure S(>0. — X-ray and electrotherapeutic machine. High-frequency type,
wide, IS inches deep, 48 inches high.
Size: 24 inches
Figure 363 illustrates what is called a dental
Dental X-Kay Unit. X-ray " unit." There are several points of interest
regarding its construction. Let me describe the one
illustrated.
Electrically it is an induction coil with an electrolytic interrupter.
The first " units " were all induction coils. (Recently " units " of the
Tesla or high-frequency type have been placed on the market.) Being
small it is easily movable and so, with the tube fastened to the adjustable
upper part, it acts as a tube stand.
The X-ray tube used with this unit is a special one. First, a valve
tube to cut out inverse is built into it as is indicated by the illustration
(Fig. 363) which shows two, instead of the usual one, bulbular part.
Second, for protection the bulbular part of the X-ray tube proper is made
of lead glass save for a window of ordinary glass through which the
X-rays are directed on the part to be radiographed. (When in operation
the tube fluoresces blue except just at the window of ordinary glass which
X-RAY MACHINES
327
Figure S61. — Overhead wiring system.
328
APPENDIX
gives the usual green color.) Third, a small glass compression cylinder
is attached as part of the tube. Fourth, the regulating chamber and the
cathode end of the tube are connected with a special connection the func-
tion of which connection is to allow " just enough " current to pass
Figure 3G2. —
through it, and so through the regulating chamber, to keep the vacuum of
the tube constant, i. e., to keep it from raising.
It will be seen from the foregoing that the idea of the " unit " is
simplification for the operator and indeed as long as all parts are in good
working order radiographs may be made with it by simply posing the
patient and switching on the current for the proper length of time. When
it becomes necessary to make some adjustments, however, the operator
will then feel the need of the information set forth in the first one hundred
pages of this book.
X-RAY MACHINES
329
Figure 363. — Dental X-ray '"Unit." Size: IS inches wide, IS inches deep, 46 inches high.
330 APPENDIX
The " Hogan silent Roentgen transformer " is
VB^.. iM^^us^A said, by its manufacturer, to be a transformer or in-
terrupterless type of X-ray machme which is so con-
structed that it rectifies its output current without a synchronous rectify-
ing disc or switch. Other manufacturers tell me they may put such an
X-ray machine on the market.
the X-Rav Outfit ^^ X-ray outfit consisting of a transformer, a
Admitting of the Coolidge X-ray tube and an automatic time switch
RcHabk Control ^*i"^its of the most perfect and reliable control, with
the least effort on the part of the operator. Such
an outfit is expensive.
X-RAY TUBES AND THE X-RAYS
APPENDIX TO CHAPTER III
331
X'Rdv Cubes and the X-Rays
Beginners in X-ray work seem unable to reconcile themselves to
accept the statement* that the cathode stream passes from cathode to
target. See page 49. So let me emphasize the statement: The cathode
stream flows in the opposite direction to the flow of the electricity through
the tube.
Recently it has been satisfactorily proved that the X-rays can be
reflected. This is of only academic interest, however, since no practical
use of the knowledge has so far been made. The operator back of a lead
screen, using a mirror to observe his tube and patient, must not think from
this that the mirror will reflect the X-rays to him as it reflects the image
of the tube and patient.
Figure 364. — Coolidge X-ray tube.
eoolidge
X-Kay tube.
other X-ray tubes.
The new Coolidge X-ray tube (Fig. 364) built
by W. D. Coolidge in the research laboratory of the
General Electric Company, differs radically from all
Uacuum
Control.
It differs from the ordinary X-ray tube described
in Chapter V so much that it is difficult to compare
the two. When the current will not pass through an
ordinary X-ray tube, as we wish it to, we lower the vacuum of the tube
by liberating gases in it, and we may then force a variable amount of
milliamperage through it ; depending on where we place the lever of the
332 APPENDIX
X-ray machine rheostat. No current at all will pass through the Coolidge
tube until the tungsten filament or coil (Fig. 365) is heated, and then not
more than a certain amount will pass through, regardless of how far the
lever of the rheostat of the X-ray machine is advanced. The degree of
heat of the tungsten filament controls the limit of the milliamperage which
may be sent through the tube.
The vacuum of the Coolidge tube is very high and remains practically
the same always. Temperature of the tungsten filament — i. e., ionization
— and not changes in degree of vacuum due to gas liberation, governs
the amount of milliamperage which may be sent through a Coolidge tube.
B.
Figure 30.5. — Cathode of Coolidge tube.
When a Coolidge tube is seen in operation for the
TlUOrcscCttCC. first time the observer is surprised to find that it does
not fluoresce. The heated filament is seen and, if the
current is left on long enough, the target may get red or white hot, but
the green fluorescence of the ordinary X-ray tube does not occur at all.
If the polarity of the machine is wrong, it will be shown by the fact
that the milliammeter will register no current, regardless of how high
the filament temperature may be, for the Coolidge tube allows current to
pass through it in only one direction ; from filament to target.
In the practice of radiodontia one need have little
l)Catinfl. fear of overheating a Coolidge tube. The tube will
take greater quantities of current over a longer period
of time than the radiodontist will find it necessary to use, unless the
Coolidge tube is one of the finest focus, when, to keep from burning the
target, not more than about 25 milliamperes should be sent through the
tube.
^ X-RAY TUBES AND THE X-RAYS 333
. The Coolidge tube has no assistant anode or
roolidae Cube regulating chamber; it has only a cathode and an
anode or target. Figure 365 is an illustration of the
cathode.
" The filament (A) Fig. 365, which forms the cathode, consists of
a flat closely wound spiral of tungsten wire. By means of a rheostat the
heating current sent through the filament may be varied from 3 to 5
amperes.
" The focusing device consists of a cylindrical tube of molybdenum
(B), Fig. 365, mounted concentric with the tungsten filament and with its
inner end projecting about 0.5 mm. beyond the plane of the latter. Be-
sides acting as a focusing device it also prevents any electron discharge
from the back of the cathode.
Figure 366. — Anode of Coolidge tube.
" The anti-cathode or target, Fig. 366, consists of a single piece of
wrought tungsten (C) attached to a molybdenum rod (D) and supported
by a split iron tube (E).
" The cathode filament may be heated by means
rathode Tilament *^^ ^ storage battery or a small transformer. The
battery is universally applicable. The transformer
can be used wherever there is alternating current available, either from
the supply mains or from a rotary converter. In case it is necessary to run
from the same source of supply as the X-ray transformer the filament
current transformer is not to be recommended for radiographic work
where there is much line drop. In many cases, however, there are two
•separate sources of alternating current supply and then the filament trans-
former is to be recommended for everything.
" In Fig. 367 the tube is shown properly con-
Connectlons. nected to tTie storage battery and the X-ray machine.
It must always be borne in mind that the entire bat-
tery circuit is brought to the fiill potential of the tube when the tube is
energized for use and that the wires from the battery should therefore be
334
APPENDIX
as thoroughly insulated from the patient and the ground as the tube itself.
" The full circuit is shown in the schematic diagram, Fig. 367, in
which S is the parallel spark gap, M the milliammeter, B the storage
battery, or small transformer, R the rheostat for controlling the current
in the filament circuit, and A an ammeter for measuring this current. The
best technic for the Coolidge tube demands the use of an ammeter in
the filament circuit. The meter should have a 5-ampere scale large enough
Figure 367. — Diagram of Coolidge tube connections.
to be easily and accurately read. The meter should be located as close to
the operator as possible and in such a way that it can be easily read from
the operating position.
^ ^ . . .. , " The technic of various operators and the
Cecbnic for Using . -^ ^. r ,, , , 11.
Goolidae tube sources of excitation of the tube vary so much that it
is difficult to make detailed suggestions which are
universally applicable. The following general considerations, however,
may be of value :
'Bear these two things in mind: First, the higher the filament
current — i. e., the hotter the filament — ^the greater the milliamperage
which can be sent through the tube. Second, the higher the voltage backed
up by the tube — i. e., the longer the parallel spark backup — the greater
the penetration of the X-rays produced.'
X-RAY TUBES AND THE X-RAYS 335
" A simple method of starting radiographic work with the Coolidge
tube is as follows :"
' Take a case, for example, where the operator has been doing his'
work with the rheostat on the loth button with his tube drawing 30
milliamperes. In this case, all that is necessary with the Coolidge tube is
to set the main rheostat on button 10, light up the filament in the tube,
having the filament rheostat handle pushed as far away as possible — i. e.,
in — flash the main switch on as often as necessary to get milliampere
reading, and pull on the handle which lets amperage into the filament
and heats it, until the tube is seen to be drawing 30 milliamperes. Having
once adjusted the tube to this condition the operator should read and
record the amperage in the filament circuit. To reproduce the condition
he then needs merely to adjust the filament current to this same amperage
and set his X-ray machine rheostat on the same button. In this way, after
his technic is once established, he never tests his tube out by operating
it, but is guided solely by the ammeter and the X-ray machine rheostat
button.'
" In other cases, the radiographer will be accustomed to adjust his
tube by means of milliammeter and the parallel spark gap. This pro-
cedure can be applied equally well to the Coolidge tube, and will naturally
be the one first used in all cases where the operator is not familiar with
his machine."
Knowing that 20 milliamperes with a 5-inch parallel spark back-up is
desired, start by setting the parallel spark gap at 5 inches. Light the
filament of the Coolidge tube having all the resistance of the Coolidge
control rheostat in — i. e., the handle of the rheostat pushed in — and so,
the least possible current in the tube filament. Start with the X-ray
machine rheostat on a low button. Flash the main switch of the X-ray
machine whenever readings of the milliammeter are desired and manipu-
late the Coolidge control rheostat and the X-ray machine rheostat
alternately until 20 milliamperes are passing through the tube and a spark
will jump only a 5-inch parallel spark gap and no more. " Widen the
parallel spark gap now and everything is set ready for the radiographic
exposure to be made. As before the operator reads and records the
amperage in the filament circuit and the number of the rheostat button
on the X-ray machine and is subsequently guided solely by these records."
Records for each Coolidge tube must be made, as records of one tube
cannot be applied to another and the same radiographic results obtained.
" The tube may be safely run with the target at white heat. If
excessively high energy inputs are employed, the tungsten at the focal
spot melts and volatilizes. This results In a sudden lowering of the tube
336 APPENDIX
resistance and in blackening of the bulb. The instability in resistance
disappears instantly upon lowering the energy input, and no harm has
been done to the tube — that is, unless it is to be used for the production
of the most penetrating rays which it is capable of emitting. In this case,
a heavy metal deposit on the bulb is undesirable, as it interferes with
smooth running at high voltages.
" The tube should not be run with voltages higher than that corre-
sponding to a lo-inch spark gap between points (that is, it should not be
made to back up more than a lo-inch parallel spark).
" For long continued running in an enclosed space and with heavy
energy inputs, it will be necessary to provide some means of cooling the
glass, as by a small fan or blower. The glass can, however, safely be
allowed to get very hot. It is all right so long as it does not soften and
draw in.
" In running the tube on an induction coil, a valve tube should be
used in case heavy energy inputs are to be employed. So long, however,
as the temperature of the focal spot is not made to approximate that of
the cathode, the tube will satisfactorily rectify its own current.
" The tube can be furnished with three sizes of focal spots : broad,
medium and fine. For therapeutic, fluoroscopic and most radiographic
work the medium focus tube will be found suitable. If extremely sharp
definition is desired, the fine focus tube should be used."
The Coolidge tube is not in more general use for two reasons : ( i )
It is so much more expensive than the ordinary gas tube. (2) It pro-
duces a great number of vagrant X-rays (the entire stem of the anode
gives off X-rays) which sometimes interfere with the making of clear
radiographs.
The two common injuries from sending too
^^^^^ r^"^** "^"^^ current through an X-ray tube are : ( i )
Overheating of the glass and consequent puncture
in the region of the cathode. (2) Burning of the target at the
focal spot. To overcome the danger of puncture in the region of the
cathode, tubes are now made with a cathode collar, or jacket, of steel.
(See Fig. 368.) Tubes of this design are capable of transmitting much
more current than the ordinary tube without danger of puncturing in the
cathode region. Tubes with cathode collars, which the writer has seen
in operation, show a light ring in the inactive hemisphere giving the tube
somewhat the appearance of a tube with inverse current passing
through it.
The finer — i. e., the smaller — the focal point, the place where the
cathode stream strikes the target, the more likely burning of the target
X-RAY TUBES AND THE X-RAYS
337
is to occur. Thus a tube with a very fine focal spot should have not more
than about 20 to 40 milliamperes sent through it, while the same sort of
a tube with a medium or broad focal spot may transmit 80 to 200 mil-
liamperes without injury to the target.
Tungsten targets are capable of withstanding much more heat than
platinum targets.
Figure 369 shows a ring in front of the target. The functions of
the ring are: (i) To sharpen the focal spot. (2) To overcome the
Figure 368. — X-ray tube with protection cathode collar.
initial resistance in tubes of high vacuum. (3) To decrease uneven heat-
ing at the cathode.
Figure 370 is a type of valve tube differing in
mechanical construction from Figs. 51 and 52. A
valve tube of this type is built into the X-ray tube
illustrated in Fig. 83.
Some special feature, or combination tubes are
now being manufactured to operate particularly on
" Radiographic Units." These tubes may have built
into them as an integral part any one or all of the following: (i) a
valve (2) a protection bulh of lead glass (3) a cylinder, through which
Cube.
Combination
tubes.
338
APPENDIX
the X-rays are directed on the part being radiographed, to cut out
secondary X-rays (4) a filter, consisting of a sheet of aluminum in the
bore of the cylinder (5) a special vacuum-regulating device consisting of
a connection between the regulating chamber and the cathode end of
Figure 309.
1
Figure 370. — Valve tube.
the tube, which connection is of the proper electrical resistance to carry
the right amount of electricity to keep the vacuum of the tube the same.
In principle, the connection between the tube-regulating chamber and
the cathode end of the tube is a tube-regulating spark gap which is set at
a definite distance. As I have mentioned elsewhere (Chapter V) the
X-RAY TUBES AND THE X-RAYS
339
tube-regulating spark gap may be set at a certain distance and left there
while the tube is in operation. Since the resistance of the tube-regulating
spark gap, which is to be set while the tube is in operation, should be less
as the tube gets older, it is not quite right for manufacturers to claim that
the special connection now under consideration makes the control of the
tube " absolutely automatic." When the tube is new its vacuum control
may be automatic, but as it gets old manipulation (i. e., lessening of re-
Figure 371. — Hydrogen X-ray tube.
sistance) of the special connection, between the regulating chamber and
the cathode end of the tube, becomes necessary. The greatest, or as I
see the thing, the only advantage of the " special automatic (?) vacuum
control connection " is that it admits of reduction of the vacuum of a
tube without any sparks occurring, as they do at an atmospheric tube-
regulating spark gap. This is a definite advantage when the tube-regulat-
ing spark gap is at the tube, for then there is no disagreeable sparking in
the vicinity of the patient, but is not an advantage if the tube-regulating
spark gap is on the X-ray machine. (See page 49.)
340 APPENDIX
Figure 371 illustrates a type of tube known as
riih*< the " hydrogen tube " because the gas used to lower
the vacuum is hydrogen. Some hydrogen tubes admit
of regulation in either direction ; that is, their vacuum may be either
raised or lowered while others admit only a regulation of lowering.
Figure 371 shows the special device by means of which the vacuum is
regulated instead of the usual tube-regulating spark gap.
The writer's experience with X-ray tubes has
7711% A# T|^*iiiiiii ^ -^
ruh* to Kuu taught him, when purchasing a new tube, never to
buy one which backs up more than five inches parallel
spark. One which backs up only three inches parallel spark, with use, will
soon be backing up more. But a tube which backs up more than five
inches parallel spark when new will soon be backing up so much parallel
spark — i. e., will soon have such a high vacuum — that the best dental
radiographic results cannot be obtained with it.
APPENDIX TO CHAPTER V
makiitd Dental Kadiograpbs.
new Pose for Trontal, ^^^ advantage of having a well sectioned skull,
ethmoidal, and max- to the operator who wishes to do sinus work, can-
lllary Sinuses. j^q^- jjg overestimated. Before one becomes proficient
in this work, experimentation on a skull is necessary.
A comparatively new and most excellent pose for making antero-
posterior radiographs of the frontal sinuses, ethmoid cells, and antra is
illustrated in Fig. t,'/2. Fig. t,/2i is a diagrammatic drawing explanatory
of Fi(
372.
Fig. 372, Pose for frontal sinuses, antra and eth-
moids. (Published by courtesy of Interstate
Medical Journal.)
SPHENOID
SINUS
ETHMOID
CELLS
FRONTAL
SINUS
ANTRUM
Fig. 373. Diagrammatic drawing ex-
planatory of Fig. 372. (Interstate
Medical Journal.)
Figure 374 is a radiograph made from the pose illustrated in Fig.
372, and Fig. 375 is a diagrammatic drawing explanatory of Fig. 374.
Spbenoid Sinus.
mastoids.
Figures 376, 377 and 378 illustrate poses for
sphenoid exposures.
Figure 379 illustrates a pose for mastoid ex-
posures.
341
342
APPENDIX
Fig. 374. Radiograph made from pose. Fig. 372. {Interstate Medical Journal.)
f-^
Fig. 375. Diagrammatic drawing explanatory of radiograph, Fig. 374. (Interstate Medical
Journal.)
MAKING DENTAL RADIOGRAPHS
343
344
APPENDIX
This device (Fig. 380) facilitates the interpre-
tation of radiographs of the head. Correct inter-
pretation is sometimes more difficult on account of
the light area around the radiographic image on the negative. The In-
Troittal Sinus
Tntensificr.
Fig. 379. Pose for mastoids. (Interstate Medical Journal.)
tensifier is simplicity itself. It consists of heavy lead plate which fits
into a surrounding heavy iron frame ; both are covered w^ith felt. Place
the intensifier on the plate. The lead plate is now removed and the
patient's head is placed in the frame. The exposure is made and the lead
plate replaced. The iron frame is then removed carefully, leaving the lead
plate covering the part which has been exposed. Two flashes of the X-
rays, after the removal of the frame, exposes the photographic plate
where the frame has rested and makes the negative black, except just
that part of it on which the radiograph appears.
MAKING DENTAL RADIOGRAPHS
345
Figure 381 illustrates a " kassett " or plate holder
K^SSCtt. which may be used instead of envelopes to protect
plates from light while handling them to make radio-
graphs. Kassetts are especially useful when intensifying screens are used.
Fia. IjSO. P^Kintiil siiui^ intLiibifier.
-— I
tbc Benoist
Penetrometer.
Fig. 381. Kassett.
The exact penetration of the X-rays can be de-
termined accurately and easily by the use of the
Benoist penetrometer. (Fig. 382.)
Lay the penetrometer on the plate where it will be exposed while
the exposure for the radiograph is being made. When the plate is de-
veloped the radiograph of the penetrometer will appear as a circle of
varying shades surrounding a circle or spot. The shade, counting from
the darkest as number one, which matches the center or spot is the pene-
tration of the tube on the Benoist scale.
" Very low vacuum tubes showing a penetration of only about tWQ
346
APPENDIX
will not give good radiographs of any part thicker than the hand, regard-
less of the length of exposure. Before such a tube is used its vacuum
should be coaxed up by running a current of two or three milliamperes
through it for a few minutes each day."
Fig. 384A. Ketchan film-holder in posi-
Fig. 383. Small lead protection box for films. tion for lower third molar.
Repeated and prolonged efforts to make radiographs with a tube,
the vacuum of which is too low may result in producing an X-ray burn.
When a tube gives 8 or lo Benoist penetration it will probably not
make good radiographs. They will be lacking in contrast because the
X-rays are so penetrating that they penetrate bone and soft parts alike.
Negatives made with a tube of such high penetration sometimes, besides
lacking contrast and detail, will show a brown color from the glass side
of the negative. This brown color is indicative of what is called " burn-
ing up the emulsion " with a " too-high " penetration.
Figure 383 ilustrates a small lead box ; inside
Small Ewd Box. dimensions about 5x6 inches, which is a most prac-
tical one for small dental films.
MAKING DENTAL RADIOGRAPHS
347
Hctcbam Tilm
Figure 384 illustrates the Ketcham film holders,
the most elaborate set devised. Figure 384A is a
radiograph showing a Ketcham film holder in posi-
tion for a lower third molar.
Fig. 3t>6. Dental radiograph made
directly on bromide paper.
Fig. 385. Radiograph made on bromide paper.
Fig. 387. The negative for this
radiograph was made at the same
time with Fig. 386, the film and
the bromide paper being enclosed
in the same packet.
Hadi09rap1)$ made
on Paper.
Instead of using a photographic plate or film, a
radiograph may be made directly on photographic
paper. This paper should be the most sensitive made,
so that the exposure will be as short as possible. Glossy " bromide " paper
is the best. Figure 385 illustrates a radiograph of the hand made di-
rectly on bromide paper. (Reduced one-half.)
Direction Of X-ravs Figures 388 and 389 show very clearly that di-
tbrougb the tectl) rectmg the X-rays through the posterior teeth at right
Tigs. 3$$ and 3$9. angles to the long axis of the tongue does not mean
at all that the rays pass straight through the tooth from buccal to lingual
348
APPENDIX
Lines A at right angles to long axis of tongue; lines B straight through
the teeth from buccal to lingual.
Fig. 389.
If it is at all possible, it is certainly most desir-
able to have the dark room well ventilated. The
writer uses a " Sirocco " suction fan to force air into
the dark room and a ventilator diagramed in Fig. 390 to provide a
means of egress. No light is let in by this arrangement. In very hot
Uentilation of
Dark Room.
MAKING DENTAL RADIOGRAPHS
349
weather, open the ice box or refrigerator (if the dark room is equipped
with one) and direct the breeze of an electric fan onto the ice. This will
lower the temperature of the room quite noticeably.
Figure 391 illustrates how an extra-oral radio-
graph may be made on a comparatively small film.
By means of the Van Woert film holder and in-
dicator, the X-rays may be directed at right angles
to the surface of the film. When radiographing the
upper teeth, it is not the exactly correct pose to have the X-rays strike the
film surface at right angles ; it is almost correct, however.
Small €xtra-Oral
Radiograph on Tilm.
Uan moert Tilm
1)0l(lcr and Indicator
Tig. T.
. 391. Pose for extra-oral radiograph
made on film, and the radiograph.
Beginners will probably find the indicator a help. Men experienced
in the practice of radiodontia will not be likely to use it except as a means
of making a series of exposures of the same part when they particularly
desire to make each exposure with the rays passing through the parts and
striking the film at the same angle every time. As a means of duplicating
a pose exactly, an indicator of some sort is a necessity.
The soft tube technic for dental radiographic
rffhMlf work is becoming definitely more popular. The
parallel spark gap is set for only about 4 inches and
the tube so reduced in vacuum, if necessary, that even this short gap is
not " backed up." Splendid black and white negatives are made by this
technic. It is important to know that the time of exposure necessary,
and so the milliampere-second dose, is greater when the soft tube technic
is employed.
Both Drs. Ottolengui and Barber, each indepen-
Rubff Dam^cffl) ^^"^ °^ *^^^ other, have suggested to the writer that
a rubber dam clamp may be used to hold the film
packet in position during the exposure.
350
APPENDIX
Ucrtical Position of The man who makes only a few film, dental
films in Developer radiographs will find it convenient to use a glass
rlXCr. tumbler or cup instead of trays for his developing
and fixing solutions and wash water. Fasten the exposed films to a hook
clip. (Fig. 119.) Hook the clips over the side of the tumbler or cup
suspending the film inside. This makes the handling of the films very
easy and affords the advantage of having the films in the developing and
Fig. F. Van Woert film-holder and indicator.
fixing solutions in a vertical position so no sediment can settle on the
sensitive surface.
,, ,, „, .- A vessel, something like a berry dish, will be
UCSSCl for UlasDing ^^^^^ ^^^^^^ ^^^^ ^ ^^^^ foj. cashing small film
tllm negatives negatives, for the water falling from a faucet causes
more movement of the water in such a dish and so washes the negatives
better and quicker. Negatives can be picked up in such a dish with
greater ease than they can from a tray. Such a dish should not be used
when the tap water is warm, as the movement of the negatives will scar
them.
In cases where there is an excessive flow of
$alit)ation. saliva, particularly when the outfit used necessitates
a rather long exposure, if the films are protected
from moisture only by paper, it is expedient to take the film
packet from the mouth after exposure and immediately squeeze it
between pieces of blotting paper. This may avoid wetting the films inside
the packet.
MAKING DENTAL RADIOGRAPHS 351
Old n^D^lou^r With use both the developing solution and the
and fixer fixing solution will wear out and cease to act on
plates or films. Wornout developer produces a
weak, poor negative. Wornout fixer will not dissolve out all the
unacted-upon silver.
Development Ulben When an intensifying screen has been used
Tntensifying Screen "highlights" appear immediately when the plate or
is Used. film is placed in the developer. The rule to develop
20 times as long as it takes for the highlights to appear does not apply
when an intensifying screen has been used.
Ceaving Dark Rocitl ^^' while the film or plate is in the developer, it
During Development becomes necessary to leave the dark room, the
Of negtltive. tray containing the developer and the developing
plate or film may be covered with a heavy board on the down side of
which is tacked or glued thick felt or plush. This will protect the film
or plate from exposure to light when the dark room is opened. If a
light-proof drawer is available, it is better than the board; the tray may
be placed in the drawer when the dark room door may be opened with
safety.
Instead of washing the negative in running water
**l)ypo-€liminator." for 30 minutes, after fixing, negatives may be
soaked in "hypo-eliminators" for about 5 minutes,
then rinsed in water, and dried. "Hypo-eliminators" may be purchased
at photographic supply houses ; directions for their use accompany them.
The advantage in using them lies chiefly in the saving of time. They may
also be used in the summer to advantage, when tap water is so warm
that it softens the emulsion and washing is fraught with the liability of
spoiling the negative.
When,in the course of a day, a number of radio-
forldentifSion^ graphs are made of different patients, unless each
negative bears some distinguishing mark, one
patient's negatives may be mistaken for another's. To avoid this con-
fusion, number the patients as they are received, then number the nega-
tives so : As soon as the films are unwrapped in the dark room, place the
patient's number in a corner of the film, marking it on the sensitive side
with a lead pencil. The lead pencil mark can be seen on the finished
negative.
Lately I have seen an elaborate system of marking each negative,
where several are made of the same mouth, to enable the operator, from
the markings, to determine what part of the mouth each negative repre-
sents. If the sensitive side of the film presents toward the teeth at the
time of exposure, as it should always, the operator should be able to
determine, from the appearance of the radiograph, what part of the
mouth it represents. And if an operator cannot do this, he does not know
enough about radiodontia to interpret dental radiographs at all.
352
APPENDIX
As the name implies, fogged negatives have a
Tossed Plates. foggy appearance. Fogging may be produced in
many different ways. For example (i) By the
X-ray light, if the lead of the protection box is not thick enough or
if it is placed too close to an active X-ray tube. (2) By a dark
room lantern which gives too much light. (3) By getting the plate
too near the dark room lantern. (4) By exposure to X-rays in some
office other than your own ; the postman might carry your films or
plates into another office before delivering them to you. (5) By using
the developing solution too warm. A fogged plate is sometimes referred
to as a "light-struck" one. When the action of the fixing solution is
well under way, but not complete, the negative appears to be fogged.
J. . _ "In extremely hot or damp weather or in hot
Summcirtinie tip. dark rooms, plates will dry quicker, and stand a
very warm wash water if you will put them into a
tray containing a solution of i oz. of chrome alum to 10 ozs. water for a
couple of minutes after removing them from the developer solution.
"The developer temperature, remember, should always be between
65° and 68° Fahr. to give the finest results."
If you do not have a thermometer to determine the temperature of
the developer, get one.
An ice box in the dark room in the summer is worth more than it
costs.
Along with much other valuable information
ni J^^^^ iP Geo. W. Brady gives the following in his excellent
Plate nesatlm. p^^phiet "Paragon X-ray Pomters :"
" Ninety-nine per cent, of plate defects are due to careless manipula-
tion in the dark room.
"Pitted negatives are due to too slow drying. The gelatine swells
and gelatine eating microbes settle on the plate, leaving transparent spots
of blotches.
"Stains are generally due to improper fixing. The hypo may be
decomposed or the bath may not contain sufficient acid. If the plates are
not rinsed thoroughly, sufficient alkali would soon be carried over from
the developer to neutralize the acid in the hypo bath. This may cause
green or blue stains, even though the plate is fixed in absolute darkness.
Stains may be due to insufficient washing. Greenish stains, pink by
transmitted light, are usually due to too warm developer, or too long
development of under exposed plates. Examination of the plates by a
bright light before fixation is complete should be avoided.
"Pin holes are always a defect in the handling of the plate. They
are never the result of defect in manufacture. They may occur in either
tank or tray development. The remedy is to go over the surface of the
plate with cotton or to rock the plate vigorously when first put into the
developer.
"Semi-transparent spots on plates developed in tanks are generally
due to air in the water due to high water pressure, or to the cold and
MAKING DENTAL RADIOGRAPHS 353
hot water pipes running closely together. The remedy is to stir the water
thoroughly and then allow it to stand long enough for the air to escape.
"Irregular transparent spots may be due to oil getting on the film,
or to a scum which sometimes occurs on the surface of the developer
when left standing for some time.
"Black spots, sometimes with a tail, are due to iron getting into the
solution, possibly from the water pipes.
"Small dark spots with sharp edges are generally caused by water
spattering on the plates before development.
"Streaky plates may be caused by an old hypo solution in a ribbed
fixing box. They may also be due to always rocking the tray in one
direction.
"Defective plates are so rare that the trouble can generally be
located in the X-ray laboratory. If any question should arise, send the
manufacturer of the plates the numbers on the bottom of the box,
together with a few of the unexposed plates, or allow some fellow radiog-
rapher to expose and develop some of your plates without telling him
what your troubles are."
A small film dental negative which is finely checkered with little
dark lines is one which has been spoiled by warm solutions or warm wash
water.
Danger of ToSding "It is not good policy to have the ruby light
Tfom Dark Room shining into the tray throughout the entire course of
Cantcrn. development ; in fact, it is advisable that the red
light be only allowed to shine on the plate when the developer is poured
on to see that it is properly covered and then the tray kept shaded from
direct light till development is nearly completed.
"Remember that very few lights are safe. To test yours, take a
small plate, lay a bunch of keys on it directly under the light at a
distance of about a foot for a couple of minutes, then develop the plate
in darkness with your regular developer for four or five minutes. If
your light is an unsafe one, the bunch of keys will show distinctly on the
plate."*
Photographic prints made on paper from nega-
Ifiaking rrilttS tives may be made more glossy and altogether more
^* beautiful by placing them on a ferrotype, or squeegee
board. The ferrotype is a sheet of metal on one side of which is baked
black enamel. After the prints are washed they are laid face down on
the enamel side of the ferrotype, and rolled with a rubber covered roller
made for this purpose. The ferrotype is now set on end, and as the
prints dry they fall off or can be picked ofif. Before placing the prints on
the ferrotype the enamel surface should be polished with ferrotype polish.
Ferrotype polish is a solution of paraffin in benzine. It is put on the
ferrotype, allowed to dry for a few minutes, then the enamel surface
polished with chamois skin. If the prints do not come off the ferrotype
as they should, but stick tightly, more paraffin may be added to the
polishing solution. Several things may cause prints to stick to the ferro-
* " Paragon X-ray Pointers," by Geo. W. Brady.
354
APPENDIX
type. If left in the wash water too long or if too much pressure is
brought to bear on them with the roller they will stick. Washing the
ferrotype with soap and water will assist in preventing sticking of the
prints. Occasionally a ferrotype will be found on which the prints always
stick and it must be discarded and another ferrotype obtained.
Lantern slides may easily be made from a good
Eantern Slides. negative. A lantern slide plate is a photographic
plate 3K^4 inches, manufactured especially for the
purpose. Like all other photographic plates, it should be " worked " in the
ruby, never the orange, light. The negative is placed in the printing
frame, sensitive side up, and the slide laid over it, sensitive side down.
(We are making what is called a "contact" lantern sHde; the lantern
slide plate is in contact with the negative.) The average celluloid, dental,
radiographic negative is of such density that the time of exposure of the
plate to a i6-C. P. electric light, at a distance of two feet, is about i
second. Allow the slides to remain in the developer a few seconds after
the radiograph shows best, until it shows a little too dark. Rinse in water
quickly and transfer to the fixing bath, where it should remain until the
picture shows clearly as desired. The writer uses Imperial lantern slide
plates and Seed's prepared metol-hydrochinone developer. After fixing,
the slide is washed and dried the same as any photographic plate. When
dry a piece of transparent glass, the same size as the slide, is laid on the
film side of the slide and the two stuck together at their edges with binding
tape, such as is used for passe-partout work. The piece of clear glass is
used to protect the emulsion of the slide against scratching.
When a lantern slide of a negative larger than the lantern slide plate
is desired, a contact lantern slide cannot be made? An apparatus similar
to the one illustrated in the Appendix to Chapter X for enlargement, must
be used. Light is directed through the negative, then through a reducing
lens onto the lantern slide. When the lantern slide desired is from an
extra-oral dental radiograph, even though the plate used is as large as
8xio, the size of the lantern slide will usually cover the part of the
negative of interest and so the lantern slide plate may be placed over the
area of interest and a contact lantern slide made of that part of the
negative.
Dr. Kells makes lantern shdes of, instead of from, his celluloid dental
negatives. This is accomplished as follows :
On a clear glass 3^x4 inches place a piece of black paper the same
size, with a hole in the center large enough to show all of the negative that
the operator wishes to exhibit. Place the negative directly over this hole
in the paper. Place another piece of glass 2>%^4 inches over the whole
and bind the two pieces of glass together at their edges with binding
strips. The advantage of this method over making photographic slides
is : The ease and dispatch with which they may be made — a dark room
and equipment is not necessary — and, since we are using the negative
itself, there is no loss of detail such as might occur when the other
method is employed and a new picture is made on the photographic slide.
The disadvantage is that the negatives with good detail are often so dark
that the light from the lantern is not strong enough to penetrate them.
MAKING DENTAL RADIOGRAPHS
355
Negatives made with the transformer (interrupterless) X-ray machines
are best for lantern sHdes because they are usually not so dense as those
made with the other types of X-ray machines.
Within a limit, the time of exposure necessary
Sbl(ffor^€xDOSurc ^^^^^^ inversely according to the milliamperes sent
through the tube. Thus the more milliamperage
sent through a tube the shorter the time of exposure necessary, or con-
versely the longer the exposure given the less milliamperage need be
sent through the tube. The action on the photographic emulsion on the
plate or film would be about the same from a 2-second exposure with 30
milliamperes passing through the tube as from a 3-second exposure with
20 milliamperes passing through the tube. So we have come to measure
exposures in milliampere-seconds. (M. A. S.)
Obtain the milliampere seconds by multiplying the number of mil-
liamperes passing through the tube by the number of seconds the current
is turned on.
If the distance between target and film or plate varies apply the rule
that the time of exposure necessary varies directly with the square of the
distance. (See Page 124).
The following is a dental M. A. S- table for exposure:
DISTANCE
TIME OF
TIME OF
KIND OF
CONDITION
FROM
FILM OR
EXPOSURE
EXPOSURE
RADIO-
OF TUBE
TARGET
PLATE
WITH ORDI-
WITH
GRAPH
TO FILM
NARY GAS
COOLIDGE
OR PLATE
X-RAY TUBE
TUBE
Dental
Back up
15 inches
Eastman
About 60
8/10 of that
Intra-Oral
about 5 inches
slow
Milliampere
necessary
parallel
seconds
with gas
spark
tube
Dental
Back up
15 inches
Eastman
About 15
8/10 of that
Intra-Oral
about 5 inches
fast
milliampere
necessary
parallel
seconds, (about
with gas
spark
Mthe
tube
Penetrometer
exposure
Benoist
necessary for
about 5
slow films)
Dental
Back up
18 inches
Paragon
About 90
8/10 of that
Extra-Oral
about 5 inches
Milliampere
necessary
parallel
seconds
with gas
spark
tube
Penetromet r
Benoist
about 5
Frontal
Back up
20 inches
Paragon
About 200
8/10 of that
Sinuses,
about =)}/2
Milliampere
necessary
Ethmoids,
parallel
seconds. (This
with gas
Antra, also
spark
milliampere-
tube
Sphenoids
Penetrometer
second
and
Benoist
exposure
Mastoids
about 6
can be
reduced to 14,
or less
by the use of an
intensifying
screen)
356
APPENDIX
It is of passing interest to compare the dental milliampere-second
table with a milliampere-second table for other parts of the body.*
(After Geo. W. Brady.)
KIND OF
RADIO-
GRAPH
CONDITION
OF TUBE
DISTANCE
FROM
TARGET
TO PLATE
MAKE OF
PLATE
TIME OF
EXPOSURE
WITH ORDI-
NARY GAS
X-RAY TUBE
TIME OF
EXPOSURE
WITH
COOLIDGE
TUBE
Hand
Back up
about 53^
inches of
parallel
spark
1 8 inches
Paragon
i8M. A. S.
A the
exposure
necessary
with gas
tubes
Wrist, lateral
Ditto
Ditto
Ditto
27 M. A. S.
Ditto
Elbow
Ditto
Ditto
Ditto
35 M. A. S.
Ditto
Ankle, lateral
Ditto
Ditto
Ditto
44 M. A. S.
Ditto
Ankle,
antero-
posterior
Ditto
Ditto
Ditto
62 M. A. S.
Ditto
Knee, lateral
Ditto
Ditto
Ditto
62 M. A. S.
Ditto
Knee,
antero-
posterior
Ditto
Ditto
Ditto
70M.A. S.
Ditto
Shoulder
Ditto
Ditto
Ditto
105 M. A. S.
Ditto
Kidney
Ditto
Ditto
Ditto
175 M. A. S.
Ditto
*Size of patient: 160 lbs.
tb« Explanation of the The beginner in radiodontic work is very much
InwVl xffi"inacbin<^^^ surprised and confused when he learns that Dr. A.,
* who has a large, powerful and elaborate X-ray outfit
" exposes his dental films 5 seconds," while Dr. B., who has a very
small outfit " exposes his dental films only i second." The explanation
is that Dr. A. is using a tube which backs up only about 3 inches of
parallel spark, while Dr. B.'s tube backs up 5 inches, or more. Dr. A.'s
target-film distance is 16 or 20 inches, while Dr. B.'s target-film distance
is about 5 inches. Dr. A. could, by using a tube of higher vacuum and
lessening his target-film distance, reduce his time of exposure, but his
negatives would not be as good ; they would not be beautifully and bril-
liantly black and white, but would become darker, less contrasty, less dis-
tinct, less perfect.
The practice of reducing the time of exposure for dental negatives
may easily be carried to the point where the quality of the negative is
sacrificed.
It is impossible to make a dental radiograph with a short exposure
with some X-ray machines of the transformer type, because they do not
produce sufficient voltage to excite a high vacuum tube. Thus some
owners and operators of such transformer machines are greatly disturbed
because their neighbor, who has an induction or Tesla coil, does not find
it necessary to expose so long. Such operators should be consoled by
observing that they produce negatives of a finer quality; their type of
machine is protecting them against the mistake of sacrificing quality for
speed exposures.
APPENDIX TO CHAPTER VI.
The following is abstracted from an editorial by Dr.
'^'''cdWa?"'* ^" ^' Jol^^son, which was published in the May,
1914, edition of the Dental Review:
the Tallibilitv of tbe X-Ray.
" It is probably true that no other discovery in recent years has been
of greater value to the medical and dental profession than has that of
the X-ray. It has aided us in clearing up many obscure lesions and has
thus been of immense value in diagnosis. In dentistry it has been of espe-
cial service in discovering impacted or delayed teeth in the jaws, and has
shed light on many a puzzling case of neuralgia by showing the cause of
the irritation. Although it is only a comparatively few years since its
introduction it would leave us bereft of much of our usefulness if it were
eliminated from our practice.
" And yet with all this it has its limitations and it is high time they
were pointed out. It has been used extensively for diagnosing abscesses
and bone lesions in the jaws and for showing the condition of root fillings
in teeth. It is useful for these purposes up to a certain point, but it is
by no means infallible and in some cases it is decidedly misleading. It
may be that we have not yet advanced sufificiently in its use to correctly
interpret its findings, but the fact is that when it comes to diagnosing
bone absorptions and alveolar abscesses the most expert X-ray men we
have are often very wide of the mark. Nor do we believe this can be
relied on to tell accurately whether root canals are properly filled or not.
Many a pulpless tooth has been arraigned as the culprit when the fault
lay elsewhere and many an operator has been censured for poor root
filling when his operation was not at fault. And the great danger is that
medical men will be extensively misled about dental operations as inter-
preted by the X-ray. Already some of them are reading all sorts of
disaster as the result of root filling. If a patient has a pain somewhere
about the jaws they are making X-rays — which in itself is perfectly
proper, and which in many instances will throw light on the trouble —
but they are reading into these X-rays much evidence which is not com-
patible with fact. It does not follow that because a radiograph shows a
dark area around the end of a root that the bone is all absorbed at that
357
358 . APPENDIX
point or that there is an abscess cavity there. It does not prove thai a
root canal is not well filled because the radiograph fails to show a filling
to the apex. We must be more discriminating in reading radiographs
than we have been in the past if we are to avoid doing harm to the
patient.
" A single instance, illustrative of many others which might be men-
tioned, will serve to prove the present contention. A patient had pain
in the region of the left upper cuspid. This tooth was banded as the
middle pier to a bridge. A radiograph was made of the region, and the
verdict of the radiographer was that there was an extensive abscess
cavity around the cuspid with the bone all absorbed. His remark was :
' If you cut the band the cuspid will drop out. Nothing holds it in place
but the gold band.'
" The band was cut and the cuspid was found perfectly firm — the
thing that nearly dropped out was the bridge, the cuspid having been its
chief support. Thinking from the evidence of the radiograph that there
must at least be an abscess on the cuspid it was drilled into — only to find
a live pulp. Here, with the best intentions, a wrong was done the patient,
on the evidence of the X-ray, and it is probably not an isolated case.
" This article is not intended as a reflection on the great utility of
the X-ray, which is cheerfully acknowledged, but merely to counsel
caution on the part of those who invariably * see things ' in every radio-
graph that is taken."
HbStfact from tbC The writer's answer to Dr. Johnson's editorial which
Dr? Johnson's ^^^ pubHshed in the June, 1914, issue of the Dental
editorial* Review is now given :
Indianapolis, Ind., April 9th, 1914.
My dear Dr. Johnson :
Your editorial, " The Fallibility of the X-Rays," creates in me a
degree of cerebral unrest which, reduced to ink and paper, is as follows:
First, let me say I agree with practically everything you say, and I
am gratified to have you take such comprehensive editorial notice of the
matter. I agree with practically everything you say, and yet, if I were
writing on the subject, my title would be " The Infallibility of the
X-Rays " instead of " The Fallibility of the X-Rays."
That the radiograph has its " limitations " and that it is sometimes
" decidedly misleading " I grant you, but it is absolutely infallible ; i. e.,
incapable of error. It is always the product of definite physical and
chemical laws.
READING RADIOGRAPHS 359
You say " it may be that we have not yet advanced sufficiently in its
use to correctly interpret its findings." There you hit it. The apparent
fallibility of the radiograph lies in our interpretation of it, in our lack
of attainable knowledge which would explain " decidedly misleading "
appearances ; and, in our unwillingness to admit that it does have " limi-
tations."
You cite an illustrative case. Allow me to cite one also ; a case
which I handled a number of years ago when very little dental radio-
graphic work was being done and it was an " event " to make an " X-ray
picture of the teeth." A patient suffering from neuralgia was sent to me
for radiographic examination. I found a shadow in the region of the
pulp chamber of a lower molar and made a diagnosis of pulp stone. The
next day the man who referred the case indignantly informed me by
'phone that, on the strength of my diagnosis, he had opened the molar
tooth and there was no pulp stone in it.
With no further explanation you would count this case as one demon-
strating the fallibility of the radiograph. But then, as I have said, the
radiograph is infallible ; it is always the product of definite physical and
chemical laws. Why then, was there a shadow in the region of the pulp
chamber of the lower molar ? Something made that shadow. What was it ?
Perhaps an air bubble attached itself to the film at the time of its develop-
ment. That would cause a spot. But the shadow I saw did not have the
characteristic appearance of an air bubble spot, and, in further disproof
of the air-bubble explanation, the spot occurred on two different nega-
tives in exactly the same place. I asked to see the patient again and,
upon examination, found a filling on the buccal surface, at the gingival
line. I had mistaken the shadow cast by the cement filling for a pulp
stone.
It was my mistake. The radiograph had done what it may be de-
pended upon to do ; it had unerringly recorded densities.
You may ask if a man is not always liable to make the same mistake
I made. No. Once his attention is directed to the possibility of such an
error he should never make it.
And so one may trace the mistakes in his radiographic diagnosis,
from the radiograph, to the man who read the radiograph, in all cases
where mistakes have been made. You mention the most productive cause
of mistakes when you close your editorial by saying, " This article is not
intended as a reflection on the great utility of the X-ray, which is cheer-
fully acknowledged, but merely to counsel caution on the part of those
who invariably * see things ' in every radiograph that is taken."
36o APPENDIX
As a man who has worked to develop the field of dental radiography,
I feel grateful to you for the remark, for the greatest menace to a more
general use of the radiograph is the radiographer who never says, " this
radiograph shows us nothing." The radiograph is the most efficient diag-
nostic aid at our command, but it does not always enable us to make a
diagnosis. Radiographers must admit this and quit reading a definite
diagnosis in every radiograph, whether it is there or not, else men like
you. Dr. Johnson, will blame the radiograph for the fallibility of the
radiographer. H. R. R.
In further general consideration of this subject I quote from my
report to the Sixth International Dental Congress, London, 1914:
" I cannot consider the subject of the advantages of radiography
as an aid to diagnosis without calling attention to the fact that the good
derived from its use depends very much on the manner in which it is
used. It is unfortunate that it is not always used in vain by the man who
has no idea of the etiology of the patient's malady, and makes, or has
made, radiographs, expecting them to reveal, as on a written page, the
disease, its exciting cause and a paragraph or two describing treatment.
I say it is unforunate that the radiograph does not always disappoint
this man who expects too much of it, who forgets all other methods of
diagnosis and lazily depends on the radiograph to do all his diagnostic
work for him. It is unfortunate because it leads men to believe that the
radiograph has arrived to replace all other means and modes of diagnosis,
when in reality it has come not to take the place of, but to take its place
with, the probe, the history, the symptoms, the signs, and diagnostic tests.
" A tentative diagnosis should always be made before the case is
radiographed. Thus, for example, from the signs and symptoms, you
suspect an impacted tooth. Radiographs are made to verify or disprove
this diagnosis. If the diagnosis is verified by the radiograph a great
element of doubt as to the correctness of this diagnosis is removed from
the diagnostician's mind. If the tentative diagnosis is disproved by the
radiograph, an important step has been made in diagnosis by elimination.
" Another example : from signs, symptoms, probing and tests we
make a diagnosis of alveolar abscess of an upper cuspid tooth.
" A radiograph is made, and we learn that we have not only an
abscess of the cuspid but of the first bicuspid also. The radiograph has
verified our diagnosis and elaborated on it.
" To epitomize : if you would derive the greatest benefits from the
radiograph, use it only to verify, or disprove, and elaborate on tentative
diagnoses."
READING RADIOGRAPHS 361
No set of rules can be given which will prevent mis-
Jl Ei$t Of lUfSfaUW, takes in judgment rendered from radiographic read-
ings. However, as I have said elsewhere, the radio-
graph is no mere fad — it is here to stay — and so it is well that we should
learn as soon as possible the mistakes one engaged in radiodontic work
is liable to make. Accordingly the following list is given.
It is incomplete, as perforce any list of mistakes in radiographic
interpretation must be, for someone is making some new mistake every
day.
The List:
( I ) To mistake the mental foramen for an abscess cavity at the apex
of a lower bicuspid. (2) To mistake the anterior palatine foramen for
an abscess cavity. (3) To mistake the nasal cavity for necrosis of the
palate. (4) To mistake the maxillary sinus for an abscess cavity at the
apices of the upper bicuspids and molars. (5) To mistake the inferior
dental canal for a fistulous tract. (6) To mistake the mandibular fora-
men for osteoporosity, due to disease. (7) To fail to bear in mind
that there is such a thing as a normal periapical space. (8) To mistake
a dark spot, due to somewhat unusual porosity, for an alveolar abscess.
(9) To mistake a shadow caused by the spinal column for necrosis of the
mandible. (10) To mistake the lingual tubercle for a bone whorl or the
shadows on either side of the lingual tubercle for osteoporosity due to
infection. (11) To mistake the hyoid bone for " some " pathologic lesion.
(12) To mistake the larynx for an abscess cavity in the neck. (13) To
make a diagnosis of antral empyema because one antrum happens to be
smaller than the other. (14) To mistake the coronoid process for the
root of a third molar. (15) Without taking into account the angle at
which the X-rays were directed toward the tooth and film, to assume that
a canal filling does not reach the apex of a root when it does. (16)
Without taking into account the angle at which the X-rays were directed
toward the tooth and film, to assume that the buccal roots of upper
, bicuspids and molars are much shorter than the lingual roots of the same
teeth. (17) To assume that a perforation through the side of a root
does not exist because it cannot be seen to the mesial or distal. (18) To
assume that a broach is following a canal because it cannot be seen
extending too far to the mesial or distal. (19) To mistake a canal filling
passing into a crooked root for a canal filling material passing through a
perforation through the side of the root. (20) To state definitely from
the appearance of flat radiographs (not stereoscopic radiographs) that
impacted teeth lie to the lingual or facial of the other teeth. (21) To
mistake a small cervical filHng for a pulp stone. (22) To assume that a
362 APPENDIX
filling in the crown of a tooth enters the pulp chamber when it does not.
{2T,) To assume, from the appearance of flat radiographs (not stereo-
scopic radiographs) that the root of an upper posterior tooth penetrates
the antrum. (24) To fail to take into account that an abscess cavity may
lap to the lingual or facial of the adjoining teeth giving the radiographic
appearance of their involvement but without involving them. (25) To
fail to consider the element of depth when judging the size of an abscess
cavity. (26) To mistake normal resorption of bone, due to age, for
pyorrhea alveolaris. (27) To fail to take into account the effect the tip-
ping of a tooth to the lingual or facial will have on the appearance of the
tooth in the radiograph. (28) To state definitely that a rarefied area
at the apex of a root represents infection without considering the anatomy
of the parts and the symptoms and history of the case. (29) To state
that no infection exists because no abscess cavity can be observed. (30)
To fail to bear in mind that osteodensity as well as osteoporosity may be
caused by infection. (31) To assume, when observing an abscess cavity
at the apex of a tooth with a well-filled canal, that the abscess occurred
after canal filling. (32) To expect to see a fistulous tract. (33) To give
a positive diagnosis of pulp stones from the appearance of one radio-
graph. (34) To try to make one radiograph do the work of two or
several. (35) To mistake hypercementosis for a poorly made radio-
graph. (36) Not to know the difference between a good radiograph
and a poor one. (37) To make just one radiograph of a part and stop,
calling it a radiographic examination. (38) To depend on intra-oral
radiographs alone, especially in cases of neuralgia, facial fistula, impacted
third molars, and abscess of the lower bicuspids. (39) To fail to use a
reading-glass when studying negatives and so avail one's self of the great
assistance rendered by the practice. (40) To fail to use the electric test
for vitality of pulps in connection with radiographic examinations. (41 )
To make radiographs of every tooth in the mouth in all cases where the
teeth are being examined to locate foci of infection.
We will now proceed with a short consideration of each of the fore-
going mistakes :
I. To Mistake the Mental Foramen for an Abscess Cavity at
Apex of a Lower Bicuspid.
Figure 392 shows the mental foramen. The location of this foramen
varies greatly in different individuals. It may occur in such a position in
a radiograph as to have the appearance of an abscess cavity at the apex
of the second or first, lower bicuspid (Fig. 393). When the radiograph
is made on a small film held in the mouth and the rays have been directed
from below upward this is especially likely to occur.
READING RADIOGRAPHS
363
-TT
Fig. 392. The mental foramen below and between the apices of the roots of the lower bicus-
pids. (Radiograph by Cole and Beeler, Indianapolis.)
Fig. 393. The mental foramen at the apex of the lower second bicuspid, having the appear-
ance of abscess cavity.
3^4
APPENDIX
Plates are better than films to differentiate between the mental fora-
men and an abscess cavity because the radiographic shadows on them are
less likely to be distorted and because they take in a greater field for
observation. In a plate one can see both the mental foramen and the
abscess cavity if one exists. If a spot having the appearance of an abscess
cavity is observed at the apex of a lower bicuspid and the mental foramen
Fig. 394. The anterior palatine
foramen having the appear-
ance of an abscess cavity at
the apex of an upper centra!
incisor.
Fig. 395. Nasal cavity spots
which have been mistaken
for abscesses of the upper
anterior teeth and necrosis of
the palate.
Fig. 396. Shovi^ing the antrum which is sometimes mistaken for an abscess of the upper pos-
terior teeth. Tlie shadow of the antrum may occur even as far forward as the apical region of
the cuspid. Fig. 459A.)
cannot be observed elsewhere, in a large extra-oral radiograph, it is prob-
able that the spot at the apex of the tooth is the mental foramen. The
tooth should be tested with the electric test, for pulp vitality, if possible.
If this test cannot be made, an exploratory, diagnostic opening may be
made into the tooth of sufficient depth to ascertain whether or not the
pulp is vital.
2. To Mistake the Anterior Palatine Foramen for an Ab-
scess Cavity.
Figure 394 shows the anterior palatine foramen. Depending on the
READING RADIOGRAPHS
365
angle of the rays and the position of the film, this foramen, which is in
the region of the apices, and between the roots, of the upper central
incisors, may have the radiographic appearance of an abscess cavity at the
apex of one of the central incisors.
3. To Mistake the Nasal Cavity for Necrosis of the Palate.
Figure 395 shows nasal cavity spots which have been mistaken for
abscesses of the upper anterior teeth and necrosis of the palate.
4. To Mistake the Maxillary Sinus for an Abscess Cavity at
the Apices of the Upper Bicuspids and Molars.
Figure 396 illustrates the appearance of the antrum which is some-
times mistaken for a large abscess cavity. It is sometimes difficult, to the
point of being impossible, to differentiate between the antrum and an
abscess cavity by the study of radiographs alone; use the electric test for
pulp vitality. See diagram Fig. 397. (See Fig. 459A.)
Fig. 397.
Diagram showing why the shadow of the antrum occurs at the apices of the roots of
the upper posterior teeth.
5. To Mistake the Inferior Dental Canal for a Fistulous
Tract.
Figure 398 shows the inferior dental canal leading forward from the
unerupted third molar. This canal was mistaken for a fistulous tract.
6. To Mistake the Mandibular Foramen for Osteoporosity,
Due to Disease.
At the mandibular foramen the ramus is thin and so this area may
appear dark in the radiographic negative.
366 APPENDIX
7. To Fail to Bear in Mind That There is Such a Thing as a
Normal Periapical Space.
It should constantly be borne in mind that there is such a thing as a
normal periapical space and that this space may be much larger in some
cases than in others. A large periapical space has about the same appear-
ance as a small abscess cavity. To differentiate between a small abscess
cavity and a large periapical space learn whether or not the pulp of the
Fig. 398. The inferior dental canal leading forward from the apical region of the lower third
molar. It was mistaken for a fistulous tract.
tooth is vital by the electric test or by making an exploratory opening. In
this connection I may say that infection may cause hypercementosis and
abnormal osteodensity, i.e., osteosclerosis, in the region of the infection,
which knowledge will assist in differentiating between small abscess cavi-
ties and normal, large periapical spaces. Figure 399 illustrates an un-
usually large periapical space at the roots of a lower molar while Fig.
400 illustrates a small abscess cavity no larger than a large periapical space
at the apices of the lower third molar. The filling material seen to enter
the pulp chamber admits of a differential diagnosis in this latter case.
(See Fig. 444, which is the same as Fig. 400 but shows the filHng in the
pulp chamber much better.)
8. To Mistake a Dark Spot, Due to Somewhat Unusual
Porosity, for an Alveolar Abscess.
Figure 401 shows what seems to be an abscess at the apex of the
READING RADIOGRAPHS
367
distal root of a lower molar. Figure 402, however, of this same tooth,
made at a different angle, shows this spot to be simply a cancelous spot
in the bone.
Some men have a tendency to call any dark area in a radiographic
negative an abscess. Figures 401 and 402 show how careful one must be
not to mistake a normal dark spot for a pathologic one. The bone is nor-
Fig. 399. Unusually large periapical
space at the apex of the roots of the
lower molar; appearance similar to
that of a very small abscess.
Fig. 400. Very small abscess at apices of roots
of lower third molar; appearance similar to
that of large periapical space.
Fig. 401. Spot at the apex of the
distal root of the anterior lower
molar; has the appearance of an
abscess.
Fig. 402. Same as Fig. 401, taken at
a different angle. The spot shows
now as a cancelous area to the distal
of the apex of the distal root of the
anterior molar.
mally much more cancelous in some individuals than in others, and the
same bone may be more cancelous in some regions than in others.
Figure 403 shows suspicious (?) areas in the apical region of the
central and lateral incisors. These areas are the nostrils, which may be
mistaken for bone rarefication, due to infection. It is unlikely that the
half-tone will show it well, but the original negative of Fig. 403 shows the
outline of the end of the nose distinctly.
9. To Mistake a Shadow Caused by the Spinal Column for
Necrosis of the Mandible.
368
APPENDIX
Figure 404 shows overlapping of the ramus and the spinal column in
such a manner as to give the ramus the appearance of being diseased to
one not proficient in the reading of radiographs. I recall also a case in
which the shadow of a vertebra was mistaken for an unerupted tooth in
the ramus.
10. To Mistake the Lingual Tubercle for a Bone Whorl or
THE Shadows on Either Side of the Lingual Tubercle for Osteo-
POROSITY, Due to Infection.
Fig. 403. Radiograph showing
the tip of the nose and the
two nostrils, which latter have
somewhat the appearance of
abscesses of the lateral in-
cisors. (Retouched.)
Fig. 404. Superimposition of the spinal column and the man-
dible, giving the latter an abnormal appearance.
Figure 405 shows the lingual tubercle, as it sometimes appears in
radiographs, simulating the appearance of a bone whorl.
11. To Mistake the Hyoid Bone for "Some" Pathologic
Lesion.
The hyoid bone, especially when it and the mandible overlap, is some-
times thought to represent some abnormal condition of the mandible or
the neck. The hyoid bone can be seen below the mandible in Figs. 255
and 287.
12. To Mistake the Larynx for an Abscess Cavity in the
Neck.
The larynx will appear as a dark area in the radiographic negative
and should not be mistaken for a pathologic lesion.
READING RADIOGRAPHS
369
13, To Make a Diagnosis of Antral Empyema Because One
Antrum Happens to Be Smaller Than the Other.
It should be borne in mind that one antrum may be much smaller
than the other and, if the radiographer does this, he will not mistake a
small antrum for a diseased one just because it happens to be smaller than
its mate on the opposite side.
14. To Mistake the Coronoid Process for the Root of a Third
Molar.
Fig. 406. Case in which the coronoid
process was mistaken for a root of
an upper third molar.
Fig. 405. Radiograph of the
lingual tubercle.
Fig. 407. In this bicuspid, one canal
filling seems to reach farther than
the other.
Fig. 408. Same bicuspid, same
canal fillings illustrated in
Fig. 407.
Figure 406 is a radiograph of a case in whicn the coronoid process
was mistaken for a root of an upper third molar.
15, Without Taking Into Account the Angle at Which the
X-RAYS Were Directed Toward the Tooth and Film, to Assume
That a Canal Filling Does Not Reach the Apex of a Root When
IT Does.
Figure 407 is an experimental case. In Fig. 407 one canal filling
370
APPENDIX
reaches the end of the excised bicuspid root while the other seems to fall
short of the end. Figure 408 is of the same bicuspid, removed from the
alveolus, and shows that both canal fillings reach the end of the resected
root.
Figure 409 diagrammatically illustrates why one canal filling has the
appearance of not reaching as far as the other in Fig. 407.
Fig. 409. Diagram explanatory of Figs. 407 and 408. A, where the shadow of the end of
the canal filling m the lingual canal is cast on film. B, where shadow of the end of the canal
filling in the buccal canal is cast on film.
Fig
410. One canal filling seems too short
and to pass to the distal too far.
Fig. 411. Same as Fig 410 after
removal of bicuspid from alveolus.
Figure 410 shows one canal filling apparently reaching the end of
the root while the other falls a little short. However, observe Fig. 411,
which is of the same tooth removed from the mouth.
Figure 412 diagrammatically illustrates how the buccal canal is
thrown to the mesial or distal of the lingual canal in Figs. 407 and 410.
By directing the rays mesio-lingually (X-rays No. i of Fig. 412), the
buccal canal is thrown to the mesial: Fig. 407. By directing the rays
READING RADIOGRAPHS
371
disto-lingually (X-rays No. 2 of Fig. 412), the buccal canal is thrown to
the distal: Fig. 410.
Fig. 412. Cross sec-
tion of an upper bi-
cuspid tooth show-
ing how the buccal
canal may be
thrown to the me-
sial (X-rays No. 1),
or the distal (X-
rays No. 2), of the
lingual canal. With
the rays passing
through the tooth as
indicated by " X-
rays No. 3," the
shadows of the
buccal and lingual
canals lie one on
the other and ap-
pear as one in the
radiograph.
BUCCAL CANAL
LIN61/AL CANAL \
Fig. 413. Showing how
the angle of the X-
rays may cast the
shadow of a canal fill-
ing reaching the end
of the root so the fill-
ing has the radio-
graph appearance of
reaching the end in
one instance and of
failing to reach the
end in the other
• 'AB."
A
B
Fig. 414. Showing
how the location of
the apical foramen
may keep a canal
filling, which
reaches the end of
the canal, from
having the radio-
graphic appearance
of doing so.
Figure 413 diagramatically illustrates how, by
figs. 413 and 414. changing the angle at which the X-rays are directed
through the parts onto the film, a canal filling which
reaches the end of the root may appear to reach the end or to fall short
of reaching the end. With the X-rays directed as lines A and B indicate,
the canal filling, as it appears on the radiograph, will not reach the end
of the root ; with the rays directed as indicated by the unmarked lines, the
372
APPENDIX
resulting radiograph will show the canal filling reaching to the end of
the root.
The lines marked A and B then may be considered to represent an
incorrect angle for the X-rays, while the unmarked lines represent the
correct angle. However, when the apical foramen happens not to be in
the bucco-lingual center of the root, but stands somewhat to the buccal,
what would ordinarily be the correct angle for the rays will cast the shad-
ow of the canal filling short of the extreme apical end. Fig. 414.
Fig. 415. Showing how the canal filling in the mesio-buccal root of a lower molar may
seem not to reach the end of the root when it does.
Fig. 416. Showing how the angle of the X-rays may make the buccal roots of upoer
molars seem much shorter than the lingual.
The thickness of the tooth, bucco-Hngually, governs to a o-reat deo-ree
the possibility of distortion in such a manner as to cause a canal filling
which reaches the end of the root to have the appearance of failino- to
do so. Thus the mesio-buccal canal of lower molars as well as the buccal
canal in upper bicuspids is especially liable to this distortion (Fig. 415).
READING RADIOGRAPHS
373
while the more cone-shaped roots (roots narrow from facial to lingual at
their apices) are almost free from the liability of such distortion.
i6. Without Taking Into Account the Angle at Which the
X-RAYS Were Directed Toward the Tooth and Film, to Assume
That the Buccal Roots of Upper Bicuspids and Molars Are Much
Shorter Than the Lingual Roots of the Same Teeth.
Figure 416 diagrammatically illustrates why the buccal roots some-
times appear so much shorter than the lingual roots. As the X-rays are
directed from a higher point in a more downward direction this distor-
tion is increased.
17. To Assume That a Perforation Through the Side of a
Root Does Not Exist Because it Cannot Be Seen to the Mesial
OR Distal.
It is a mistake to state that a perforation does not exist because
it cannot be seen to the mesial or distal. I have seen cases of perforation,
to the facial and lingual, with posts passing through them which could
not be observed radiographically. In such cases as these efforts may be
made to show the perforation by directing the rays through the tooth at
different angles, i.e., m^^?o-lingually and t^i^^o-lingually. (Fig. 419B.)
Fig. 417. Showing hole in bone caused by abscess of lower second molar.
If the perforation itself cannot be observed, bone destruction caused by
it can sometimes be seen.
In this connection I direct your attention to Fig. 417. Though the
teeth are missing, observe the hole in the bone caused by a dento-alveolar
abscess of the lower second molar. Figure 418 is a radiograph of Fig.
417. Observe now that the hole caused by the abscess is seen where the
roots of the lower second molar bifurcate. So in the practice of radio-
374
APPENDIX
dontia the operator will often find, when looking for an abscess of a lower
molar (particularly the second) a dark area in the region of the bifur-
cation of the roots and little or no bone involvement at the apices of the
roots of the tooth under observation. The dark area in the region of the
bifurcation will be looked upon as suspicious of a perforation through the
Fig. 418. Radiograph of Figure 417.
Fig. 419. What seems to be a post passing through the side of the root.
floor of the pulp chamber if the tooth is one in which there has been an
effort made to open its canals. But the liabiHty of the presence of a hole
in the external alveolar plate near the region of bifurcation should not
be lost sight of. The opening occurs in this region following the path of
READING RADIOGRAPHS
375
least resistance, the path directly buccally or buccally and downward
being through the very dense bone of the external oblique ridge. Ab-
scesses at the apices of the lower molars often show the dark area repre-
senting the abscess indistinctly, the negative having a light haze thrown
over it due to the density of the oblique ridges. Thus care must be exer-
cised or abscess areas at the apices of the lower molars — particularly the
second and third, will be overlooked.
Figure 419 shows what might easily be mistaken for a post passing
through the side of the root. Notice, however, there is no bone destruc-
tion about the post which seems to penetrate the osseous tissue. What
seems to be a post penetrating the osseous tissue is a bar for a Gilmore
attachment, for a partial plate, resting on the gum tissue.
Fig. 419A. Radiographs of an extracted crowned tooth, made by directing the X-rays
through the tooth from different angles. (By R. Ottolengui.)
Figure 419A shows three radiographs of an extracted, crowned
upper cuspid, with the post of the crown passing through a perforation
on the labial. The radiographs were made at different angles. Number
one seems to show the post following the canal; number two seems to
show the post passing through the distal side of the root, while number
three shows the post passing through the labial side of the root.
Number one was made by directing the X-rays straight through the
tooth from labial to lingual (X-rays No. 2, Fig. 419B). Number three
was made straight through from mesial to distal and number two was
made with the rays passing through the tooth in a disto-lingual direction
(Fig. 419B, X-rays No. 3),
376
APPENDIX
Figure 419C is a case from practice. Both centrals are perforated.
The two radiographs show these perforations and fail to show them as
the angle of the X-rays is changed. A careful study of both radiographs,
using a rough study sketch similar to Fig. 419B, enabled the writer to
state definitely that one post passed through the labial wall of the root
while the other passed through the other tooth to the lingual. Examina-
tion after extraction verified the diagnosis.
18. To Assume That a Broach or Wire is Following a Canal
Because it Cannot be Seen Extending Too Far to the Mesial or
Distal.
ARROW^a
^— POINT TO
FACIAL or
ROOT
CANAL
--POINT TO
LINGUAL OF"
ROOT
PLANE
FIG. 419 B.
Fig. 419B. Diagrammatic cross section of a tooth root showing how the angle at which the
X-Rays pass through the tooth may cast a shadow of a post passing tiirough a perforation to the
facial or lingual so it will have the radiographic appearance of passing to the mesial or distal
or following the canal. With the rays passing through the tooth as indicated by " X-rays No. 1,"
a post passing far enough through the root to the facial will have the radiographic appearance
of passing to the mesial while, if the post passes through the root on the lingual far enough, it
will have the radiographic appearance of passing through the side of the root to the distal.
Direct the rays through the tooth as per arrow No. 3 and the reverse is true, i. e., a facial
perforation has the radiographic appearance of being on the distal, while a lingual perforation
has the appearance of being on the mesial.
With the rays passing through the tooth as per arrow No. 2. a post passing to the facial or
Ungual will have the radiographic appearance of following the canal.
Fig. 419C. Two central incisors in the same mouth. The posts in the two centrals pass through
perforations, one to the labial, one to the lingual. The two radiographs respectively both show
and fail to show the posts passing through the perforationa.
READING RADIOGRAPHS
Z77
Figure 420 shows a wire apparently following the canal in a lower
bicuspid. Figure 421 is of the same tooth and wire, but made at a dif-
ferent angle ; the wire seems to be too far distally. In reality it is too
far buccally. iStudy Figure 422.
19. To Mistake a Canal Filling Passing Into a Crooked Root
For a Canal Filling Material Passing Through a Perforation
Through the Side of the Root.
Figure 423 shows canal filling material passing into a crooked buccal
root of an upper first bicuspid. The outline of the buccal root cannot be
Fig. 420. Wire apparently following canal in
lower bicuspid.
CANAL
Fis. 421. Same case as Fip. 420 made at dif-
ferent angle. Wire seems to pass to distal,
but in reality passes too far to the buccal.
(See Fig. 422.)
POINT TO BUCCAL
' OF CANAL
Fig. 422. Di.^gram explanatory of Fig. 421.
seen clearly and the case was diagnosed a perforation through the side of
the root with the canal filling passing through it.
20. To State Definitely, From the Appearance of Flat Radio-
graphs (Not Stereoscopic Radiographs) That Impacted Teeth Lie
to the Lingual or Facial of the Other Teeth.
It is practically always impossible to determine, from a single flat
negative, the facio-lingual location of an impacted tooth. The radio-
dontist should make stereoscopic radiographs or he should refrain from
378 APPENDIX
making himself absurd by making definite statements regarding some-
thing of which he has no definite knowledge.
21. To Mistake a Small Cervical Filling For a Pulp Stone.
See Fig. 178 and the description of it.
22. To Assume That a Filling in the Crown of a Tooth
Enters the Pulp Chamber When it Does Not.
Fig. 423. The canal filling in the crooked buccal root of the first bicuspid was thought to be
canal filling material passing through the side of the root; the outline of the buccal root is not
distinct and so was not seen by the diagnostician.
Unless the filling enters the pulp chamber as in Fig. 444 or unless
the cavity is a simple occlusal one without buccal or lingual extensions
it is usually impossible to determine whether a filling in the crown of a
tooth encroaches on the pulp or not. Proximo-occlusal filHngs and fillings
on the buccal and lingual surfaces often have the appearance of en-
croaching on the pulp when their shadow only overlaps the pulp in the
radiograph. When it is suspected that a filling encroaches on the pulp,
an ocular study of the tooth and filling should be made. This was done
in the case of Fig. 444, for example, and the outline of the cavity in the
tooth was such as to fail to explain at all the projection which seems to
enter the pulp chamber. Hence, it was assumed that the filling did
extend into the pulp chamber, and this diagnosis was accordingly made.
Had there been an extension of the filling onto the buccal or lingual of
the shape of the material, which, in this case, passes into the pulp
chamber, this extension would have been held responsible for the ap-
pearance of filling material passing into the pulp chamber.
23. To Assume, From the Appearance of Flat Radiographs
(Not Stereoscopic Radiographs) That the Root of an Upper Pos-
terior Tooth Penetrates the Antrum.
It is impossible to determine from the appearance of a flat radio-
graph whether the root of a tooth penetrates the antrum or not. The ap-
READING RADIOGRAPHS
379
pearance of the radiograph would be the same if the root passed to the
buccal or Ungual of the antrum as it would if it entered it. In radio-
graphs made on films held in the mouth the roots of teeth may seem to
enter or lap the antrum when they do neither. (Fig. 397.)
Fig. 424. Dark area in apical region
of upper cuspid. This tooth is not
abscessed; the bone change is due to
abscess of the lateral incisor.
Fig. 425. Note that a radiograph would give no
record of the labio-lingual depth of the abscess
cavity. (Courtesy Ash's Monthly.)
24. To Fail to Take Into Account That an Abscess Cavity
May Lap to the Lingual or Facial of the Adjoining Teeth, Giving
THE Radiographic Appearance of Their Involvement but Without
Involving Them.
In Fig. 424 an abscess at the apex of the lateral incisor seems to in-
volve the cuspid, but this is due to lapping of the abscess cavity to the
lingual. The cuspid is a vital tooth. It is of normal color and responds
normally to the electric test for pulp vitality.
25. To Fail to Consider the Element of Depth When Judging
the Size of an Abscess Cavity.
Figure 425 is made from a photograph of a skull. Note the labio-
lingual depth of the abscess cavity and how a radiograph would fail to
indicate the true size of the cavity. This limitation of the radiograph
must be constantly borne in mind.
26. To Mistake Normal Resorption of Bone, Due to Age, For
Pyorrhea Alveolaris.
The fact is well established that the sharp point of bone seen in radio-
graphs between teeth is lost as age advances. This change, due to age,
should not be confused with pyorrhea alveolaris.
27. To Fail to Take Into Account the Effect the Tipping of
a Tooth to the Lingual or Facial Will Have on the Appearance
OF the Tooth in the Radiograph.
38o
APPENDIX
Figure 426 shows a lower molar which seems to have very short
roots. When extracted the roots of this tooth were found to be of normal
length. Figure 427 illustrates why the roots of the molar in Fig. 426
appeared short — " the tooth was tipped lingually."*
Fig. 426. The roots of the lower first
molar seem very short, but, upon
extraction, they were found to be
of normal length.
XRAY5
XRAYS
Fig. 427. Diagram explana-
tory of Fig. 426.
To obtain a true radiographic shadow of a tooth like the molar il-
lustrated in Fig. 426 and diagramed in Fig. 427, it is necessary to direct
the X-rays lingually and downward so as to pass through the tooth at
right angles to its long axis.
28. To State Definitely That a Rarefied Area at the Apex
OF A Root Represents Infection, Without Considering the Anat-
omy of the Parts and the Symptoms and History of the Case.
It is very common practice for those unskilled in the interpretation
of radiographs to consider nothing at all except the lights and shadows in
the radiograph and to blandly call any rarefied area at the apex of a
tooth " an abscess."
That things other than infection arising from the tooth may cause a
rarefied spot at its. apex has been pointed out elsewhere — See Figs. 393,
394, 395» 396, 399, 40i, 403 and others.
When a rarefied area occurs at the apex of a root with an imperfect
canal filling, the imperfection of the canal filling causes us, almost re-
gardless of any other consideration, always to look upon the rarefied area
as one which very probably indicates infection.
Do abscess cavities, which have been freed from infection, fill with
new bone or do they fill with fibrous tissue ? The question was discussed
extensively a couple of years ago. Much evidence has been brought forth
in the form of post-operative radiographs to prove that there is a recon-
* Dr. Ottolengui.
READING RADIOGRAPHS 381
struction of bone in abscess cavities. The fact is established : bone will fill
abscess cavities after proper treatment. But this proves only that we do
get bone reconstruction in some cases; it does not prove that abscess cavi-
ties do not fill with fibrous tissue. Perhaps they do ; perhaps they do not ;
the question is not settled.
An abscess cavity filled with uninfected fibrous tissue would have
practically the same radiographic appearance as one filled with infectious
material.
Since there is no doubt at all about the possibility of getting bone
reconstruction in abscess cavities, and there is some doubt as to whether
such cavities ever become filled with uninfected fibrous, cartilasre-like
tissue (it has not been conclusively proved that they ever do) we must
consider it at least a had sign when we fail to get bone reconstruction;
then take into account the local and general symptoms and be governed
accordingly in our conclusions. (See Appendix, Chapter XI.)
Knowledge of what treatment, if any, has been given will assist in
determining whether or not a shadow at the apex of a tooth represents
infection. As the size of the originally infected area increases the method
indicated for overcoming the infection changes. A small area of infec-
tion can be overcome by forcing some disinfectant, such as phenolsul-
phonic acid or a three per cent, solution of tincture of iodine in water
through the tooth into the infected area ; a larger area can be disinfected
by the ionization method ; a still larger area may necessitate curettement
and root resection ; while extensive infection may necessitate extraction.
Thus if a shadow persists at the apex of a tooth after treatment with
phenolsulphonic acid, when the original infection was such as to indicate
extraction or at least curettement, the shadow may be said to represent
infection. After a case has been treated, when in doubt as to whether or
not a shadow indicates infection it is well to ray the part repeatedly at
intervals of two or three months. If the shadow gets larger, a diagnosis
of infection may be made; if it gets smaller we may assume infection has
been overcome for the time being, at least ; if it remains the same it is
very probable that infection has not been overcome, though, in the light
of our present knowledge of the subject, the radiograph proves nothing
conclusively one way or the other in this latter event. Noticeable bone
reconstruction takes place usually within three months and large cavities
are filled in about six months to a year.
When making a series of radiographs of the same case, great care
should be taken to have the poses for the different radiographs as near
the same as possible as change in viewpoint of observation of the part
may change appearances greatly.
382 APPENDIX
29. To State That No Infection Exists Because No Abscess
Cavity Can Be Observed.
Infection in the end of an unfilled canal and in the periapical space
may exist without destruction of bone. Just because there is not a suf-
ficient amount of the right kind of infection to produce bone destruction
Fig. 42S. Bone destruction and osteosclerosis at apex of upper first bicuspid.
does not mean that there is no infection at all. If the symptoms, local
or general, indicate infection, unfilled canals should be looked upon with
great suspicion, even if the bone is not destroyed. In such cases dense
areas in the bone and hypercementosis may be taken as contributing evi-
dence of infection.
A small abscess cavity just beyond the end of the root will always
show in a well-made radiograph, but a small abscess cavity at the apex,
on the facial or lingual side of the root, may fail to show. Visualize a
small abscess on the buccal, at the apex, but not extending above it, in
Fig. 414. It would fail to register — unless it were considerably wider
than the root of the tooth mesio-distally — with the rays passing through
the tooth as per arrow " X-rays No. 3," Fig. 412. With the rays passing
through the tooth as per " X-rays Nos. i and 2," Fig. 412, it would very
likely show in the negative. Hence, as I have pointed out elsewhere, the
necessity of radiographing the same field at different angles. A single
radiograph of a part does not, by any means, always represent a good
radiographic examination of the part.
30. To Fail to Bear in Mind That Osteodensity as Well as
OSTEOPOROSITY MaY BE CaUSED BY INFECTION.
As I have already stated (See under Mistakes 7 and 29) some osteo-
density as well as osteoporosity may be caused by infection. This
knowledge will often assist in rendering a correct judgment regarding
radiographic findings.
Figure 428 shows both destruction and eburnation or sclerosis of
bone. The bone destruction is just at the apex of the first bicuspid. Im-
READING RADIOGRAPHS
383
mediately surrounding the area of bone destruction is a rim.of dense bone.
(In this case the permanent cuspid is missing, the temporary cuspid is
shell crowned and about all of the root is resorbed.)
Figure 429 is a case in which we see an imperfect canal filling, and
evidence of osteoblastic stimulation — which is probably infective in nature
— at the apex of the second bicuspid. In this case it seems that we have
practically no bone decalcification. While the canal filling in this case
reaches the end of the root, I consider it imperfect because, judging from
the buckled, bent condition of the gutta percha point, the canal filling does
not fill the canal solidly full.
Fig. 429. Osteosclerosis apex upper second
bicuspid.
Fig. 430. Bone destruction, bone eburnation
and hypercementosis distal root,
lower first molar.
Figure 430 shows (i) bone destruction, (2) osteosclerosis, (3)
hypercementosis in the region of the apex of the distal root of the lower
first molar.
31. To Assume, When Observing an Abscess Cavity at the
Apex of a Tooth With a Well-Filled Canal, That the Abscess Oc-
curred After Canal Filling.
It is such faulty reasoning that I may say it is lack of reasoning
to point to a well-filled canal at the end of which is a large abscess cavity,
and say, "This canal filling has failed. It is useless to fill, canals as this
one is filled." Of course, the abscess cavity may have existed for years
before the canal filling was placed in the tooth, but the universal tendency
is to assume that it did not, but that it developed after the canal filling
was inserted.
It should also be remembered that there is something more to the
treatment of pulp canals than the mere mechanical filling. No difference
how mechanically perfect a canal filling may be it will fail unless the
proper aseptic and antiseptic measures have been taken. Mechanical per-
fection of the canal filling is only one factor which contributes to the
successful treatment of teeth; and, important as it is, it is not, in my
.384 APPENDIX
present opinion, as important as asepsis, antisepis and disinfection. A
canal filling which simply reaches the end of the root but does not fill the
canal full is, of course, not a good one, though it is often accepted as
such.
32. To Expect to See a Fistulous Tract.
It is a human characteristic to see the things we are looking for and
rather expect to see, or want to see. Hence, the many misinterpretations
of radiographs. It is very seldom possible to observe a fistulous tract
unless it is injected with some agent such as bismuth paste.
TfT). To Give Positive Diagnosis of Pulp Stones From the Ap-
pearance OF One Radiograph.
Even when the finding can be observed quite clearly the writer usu-
ally deems it expedient to re-ray the part before giving a diagnosis of
pulp stones.
34. To Try to Make One Radiograph Do the Work of Two,
OR Several.
It is not an uncommon mistake to try to make one small film nega-
tive take in, say, for example, the central incisor, the lateral incisor, the
cuspid and the first bicuspid. While all of these teeth might be radio-
graphed on one negative, some or all of them would be distorted. It
would be better to make two negatives.
It is a mistake to radiograph one side of the jaw looking for, say,
an unerupted bicuspid, and assume that the presence or absence of the un-
erupted tooth as revealed in the one radiograph, is sufficient to indicate
the same condition in the other side of the jaw. (Fig. 302.)
One radiograph of a part is simply one view of the part from one
viewpoint. No one thing contributes more to mistakes in diagnosis than
pinning one's faith implicitly upon the appearance of a single radiograph.
The more radiographic work I do the more I find myself radiographing
the same part again and again before venturing an opinion.
35. To Mistake Hypercementosis For a Poorly Made Radio-
graph.
In some cases of hypercementosis it is impossible to show the outline
of the root of the tooth distinctly. (Fig. 431.)
36. Not to Know the Difference Between a Good Radiograph
AND A Poor One.
Figure 432 shows a wire apparently in the canal of an upper lateral.
Figure 432, however, is a distorted radiograph due to the angle of the
X-rays and bending of the film. Figure 433 is of the same tooth, is a
good radiograph, and shows the wire passing through a perforation to the
distal.
READING RADIOGRAPHS 385
Figure 434 shows the outline of the roots of a lower, first molar
very indistinct. Figure 435 is of the same tooth but this time the rays
Fig. 4ol. Hypercementosis of upper bicuspids. The outline of the roots of the bicuspids
not distinct, due to the hypercementosis, not to some fault in technic.
Fig. 433. Same as Fi^. 432. Radiograph not
Fig. 432. Wire apparently following canal in distorted. See wire passing through
upper lateral root. Distorted radiograph. side of root to the distal.
have been directed through the tooth at a different angle (arrow No. 3,
Fig. 436) and the outline of the roots is comparatively distinct.
When the X-rays pass through the tooth as indi-
Tlg. 436. cated by arrows i and 2, Fig. 436, the outline of the
roots will be more or less indistinct ; when the rays
pass straight through the tooth, as indicated by arrow No. 3, Fig. 436,
the outline of the roots in the radiograph will be distinct unless there is
hypercementosis, osteodensity, or tipping of the tooth to the buccal or
ling-ual.
386
APPENDIX
Fig. 434. Outline of roots of lower first molar
indistinct. (Rays passed through tooth as
per arrow No. 1, or No. 2, Fiu. 4.30.)
Fig. 4.35. Outline of roots of lower first mo-
lar more distinct than in Fig. 434. (Rays
passed through tooth as per arrow No. 3,
Fig. 430.)
LOWER MOLAR
4
ARR0W*3
MESIAL
Fig. 436. Diagrammatic cross section of a lower first molar through the pulp chamber.
Fig. 436A. Wires in lower first molar. X- Fig. 436B. Same case as Fig. 43GA, made
rays passed through tooth diagonally; arrows with X-rays passing through tooth as indi-
No. 1 and No. 2, Fig. 436. cated by arrow No. 3, Fig. 436. The wires
in the mesial canals are superimposed
throughout most of their length..
READING RADIOGRAPHS
387
With the rays passing through the tooth as per arrow No. i, the
shadow of the mesio-buccal canal will be thrown to the mesial of the
mesio-lingual canal (see Fig. 436A), with the rays passing through the
tooth as per arrow No. 2, the mesio-buccal canal will be thrown to the
distal of the mesio-Hngual canal and the appearance of the radiograph
will be similar to Fig. 436A ; with the rays passing through the tooth as
per arrow No. 3 of the two mesial canals will be superimposed, one over
the other — Fig. 436B.
m
o
Fig. 43GC. Cross section of mesial root of lower molar. See text.
In this connection it may prove profitable for the
Tig. 4360. reader to study Fig. 436C, which diagrams a cross
section of the mesial root of a lower molar with the
X-rays passing through it as indicated by arrows one and two in Fig.
436. Note that the shadow cast on the film between lines B and C would
be denser than between the lines A-B or C-D. Thus on the radiograph the
outline of the root would be either not well' defined (Fig. 434) or the root
would have the appearance of having a necrotic surface (Fig. 205 is a
fine example).
Figure 436D shows two radiographs of a lower
Tig. 436D. first molar. The radiograph made on the small
film shows two very short canal fillings in the mesial
root, one of which seems to pass through the side of the root to the
mesial. In the large radiograph, made on a plate, the two canal fillings
in the two mesial roots are superimposed one on the other, and they do
not have the appearance of passing through the mesial side of the root.
The canal filling in the small film radiograph seems to pass through the
side of the root because where the filling ends the shadow of the root out-
line is faint as between lines A-B and C-D, Fig. 436C.
388
APPENDIX
Fig. 436D. Two radiographs of the same lower first molar. In one the canal filling seems to
pass through the side of the root; in the other it seems to follow the canal.
Figure 437 shows what seems to be a tumorous
TiflS. 437 and 43$. growth in the upper molar region. It is not a tumor ;
it is the malar process thrown in the position it oc-
cupies because the X-rays were directed through the parts from a posi-
Fig. 437. Malar process having
appearance of tumor.
Fig. 43S. Same as Fig. 437, made
at different angle.
tion which was too high. Figure 438 is of the same case, made with the
X-rays properly directed through the parts.
READING RADIOGRAPHS
389
Fig. 439. " Horrible Example." A number of radiographs intended to be a radiographic
examination of all the teeth in the mouth. In reality it is a radiographic examination of only
a very few teeth.
2,7. To Make Just One Radiograph of a Part and Stop,
Calling It a Radiographic Examination.
The inexpedience of depending too implicitly on the appearance of
one radiograph has already been demonstrated in this chapter.
390
APPENDIX
Figure 439 shows the result of applying the principle of making just
one exposure of a part and calling that a radiographic examination of
the part. Figure 439 is intended to be a radiographic examination of all
of the teeth, but most of the radiographs are so poor that it is really a
radiographic examination of only a very small number of teeth.
I cannot impress this point too strongly, the making of a radiograph
is equivalent to having a look at the part from one viewpoint. It is often
necessary, if we wish to make a thorough radiographic examination, to
view the part from different viewpoints. It is very often, in fact, usually
©
.LINGUAL
FILM ^.^'-'DI5T0-BUCCAL
B
C
•ME510-BUCCAL
FILM
Fig. 440. Cross section upper
first molar.
Fig. 441. Angle of X-rays,
arrow B, Fig. 440.
Fig. 442. Angle of X-rays,
arrow A, Fig. 440.
Fig. 443. Angle of X-rays,
arrow C, Fig. 440.
necessary to make more than one radiograph to view the upper molar
roots satisfactorily. Study Fig. 440.
Directing the rays through the part indicated by
TiflS. 440, 441, 442 arrow B will usually throw the mesio-buccal root
ana 443* ... , ./.,,.,
a little to the mesial of the lingual root as seen in
Fig. 441 .
Directing the rays through the part as indicated by arrow A, will
throw the mesio-buccal root farther to the mesial of the lingual root.
(Fig. 442.)
READING RADIOGRAPHS
391
Directing the rays through the part as indicated by Arrow C, will
throw the disto-buccal root to the distal of the lingual root. (Fig. 443.)
Quite often, when the disto-buccal root is thrown to the distal of the
lingual root, the end of the disto-buccal root still cannot be seen — it seems
to be absorbed. (See Fig. 429, The First Molar.) This appearance is
due to the fact that the root is so small that it does not throw a shadow
of sufficient density to be seen clearly. This must be kept in mind or the
radiodontist will mistake normal conditions for disease in the apical
Fig. 444. Unerupted, malposed, lower cuspid. Age of patient about 40.
region of the disto-buccal roots. There is also sometimes a normal
porosity of bone in the apical region of the mesio-buccal root which may
be mistaken to indicate disease if the operator does not know that such a
condition may be normal. To differentiate, apply the electric test to the
tooth to determine pulp vitality, look for osteosclerosis and take into ac-
count the degree of darkness in the suspicious area.
The roots of the second and third upper molars are often so close
together, and the malar process is so likely to cast a shadow over them,
that it is not infrequently impossible to distinguish the different roots.
392
APPENDIX
38. To Depend on Intra-Oral Radiographs Alone, Especially
IN Cases of Neuralgia, Facial Fistula, Impacted Third Molars and
Abscess of the Lower Bicuspids.
Case : Facial fistula. A radiograph, made on a small film, showed
very small spots indicating a slight infection at the apices of the roots of
a lower second molar. Continued treatment of the tooth did not benefit
the case. It was decided that the molar should be extracted, but before
doing this another radiograph was made ; this time on a large plate. The
second radiograph, made on the plate, revealed the presence of an ab-
scess at the apex of the lower first bscuspid, which tooth had no carious
cavity in it. This 'tooth, the lower, first bicuspid, was opened and treated
and the case recovered promptly. The large plate should have been made
in the first place, which would have enabled the operator to get at the seat
of the infection without delay.
Fig. 445. Unerupted, malposed, upper and lower third molars.
Figure 444 is the radiograph made of a case of neuralgia of many
years standing. The shadow in the anterior region of Fig. 444 is an un-
READING RADIOGRAPHS 393
erupted lower cuspid. Note also the very small abscess of the lower
third molar. The abscess is no larger than an unusually large periapical
space, but observe the filling in the crown of the tooth enters the pulp
chamber and there is no canal filling in the canals. Had a small film been
used and the condition of the lower third molar disclosed it is highly im-
probable that the examination would have been carried further and so the
real cause of the trouble would not have been located. I say the real
cause of the trouble would not have been located, because removal of the
malposed tooth, without treatment of the third molar, effected a cure.
When making radiographs for impacted third molars, there will be
less distortion, and the radiograph is more likely to show all, instead of
just a part, of the unerupted tooth and the surrounding parts, if it is made
on a plate.
Figure 445 is a radiograph of a case of neuralgia, in which both the
dentist and the patient insisted that the lower third molar had been
extracted. The radiograph was made in a search for an upper third
molar. It shows both an upper and a lower third molar. Of course, the
lower third molar would not have been discovered had the radiograph
been made on a small film.
The advantage of the large extra-oral radiograph over the small
intra-oral one for radiographing the lower bicuspids is given in the dis-
cussion of mistake No. i.
39. To Fail to Use a Reading Glass When Studying Nega-
tives AND So Avail One's Self of the Great Assistance Rendered
BY THE Practice.
The advantage in using a reading-glass to study dental radiographs
is so great, and the inconvenience of obtaining and using such a glass so
slight, that it must be considered a mistake not to avail one's self of this
valuable aid.
40. To Fail to Use the Electric Test for Vitality of Pulps in
Connection with Radiographic Examination.
*The use of some electric machine to test the vitality of the pulp,
I find absolutely indispensable in the practice of radiodontia. Likewise
it will be found indispensable to the general practitioner of dentistry once
he learns to use it and depend on it. The technic of applying this test
is extremely simple.
Figure 446 is a small machine, of the writer's design, which may be
used to test teeth to determine the vitahty of their pulps. In principle of
construction it is a Faradic machine. The source of the current to excite
the machine is the ordinary dry cell, such as can be obtained anywhere
* The electric test for pulp vitality is not original with the writer.
394
APPENDIX
in the civilized world. By means of a little step-up transformer or coil
the current of high amperage and low voltage,, from the dry cell, is trans-
formed into a current of comparatively low amperage and high voltage
or pressure. The amount of output current delivered by the machine is
controlled by a rheostat, or a metal sheath, which slides in between the
primary and secondary winding of the coil. With the sheath in the cur-
rent is weakest. This control is such that the output current can be
gradually increased from practically nothing to the capacity of the
machine.
^ t - * ^ II • * Plug cords, to which the " hand " and " dental "
Cccbttic for u5iitd & >
electric Pulp testing electrodes are attached, into machine. (There are
liificninc. three places or sockets into which the cords may be
plugged, marked " L," " M " and " R," Fig. 446. With the cords plugged
NTERRUPTER
r^.
EOSTAT
\HAND
LECTRODE
DENTAL
ELECTRODE
Fig. 440. Author's machine for testing teeth for vitality of the pulp. Size 8Y2 inches long,
4% inches wide, 7 inches high. To date, Dec. 6, 1917, this machine has not been per-
fected to conform fully with the writer's ideal.
into " L " and " M," as in Fig. 446, the output current is weakest. With
the cords plugged into " L " and " R " the output current is strongest.
Figure 446 is, at this time, still in the process of construction. It is my
aim to have the machine constructed so that the operator will, except in
the rarest cases, ahvays plug into " L " and " R " and find, with this at-
tachment to the machine, that he can get all the gradation of current
strength he desires.)
READING RADIOGRAPHS 395
Polarity : It makes no practical difference about polarity ; either
electrode may be attached to either socket.
The dental electrode is insulated save for the metal point at the end.
Wrap the metal point with cotton and moisten the cotton with water
or sodium chlorid solution.
Have the patient hold the hand electrode.
Turn the main switch, when there should be a humming noise. If
there is no humming noise, adjust the interrupter screw.
Start with the resistance of the rheostat in, that is, with the current
weak, and touch the tooth to be tested with the dental electrode. Advance
the rheostat as necessary to get sensation. The sensation will occur in
the tooth only — not in the hand — -providing the pulp is vital. If the pulp
is not vital there will be no sensation with the machine operating at its
capacity. Use enough current to cause the patient to jump or flinch
slightly but definitely.
Take care not to touch the patient with the dental electrode any-
where except on the tooth to be tested, as the sensation would be
unpleasant.
.»- -i^^-. . Crowned teeth cannot be tested.
Limitattons ^ , . , , , ^,,. „ ,
and Points in I eeth with large metal hllmgs : Sometime teeth
CccbniC« with large metal filhngs in them do not respond to
the electric test when their pulps are vital ; because the stimulus of the
metal filling has caused the pulp to recede so far. Sometimes, but less
frequently, teeth with large metal fillings do respond to the electric test
when their pulps are not vital, because the current is conveyed through
the tooth from the place where the dental electrode was applied into the
metal filling, through it, into the gum tissue or pericemental membrane or
approximating tooth.
Teeth with pulp stones and teeth where the pulp has receded, due
to the age of the patient, are less sensitive to the electric test.
Teeth with abraded surfaces are usually quite sensitive when the
electrode is applied to the exposed, or nearly exposed, dentin. However,
in some such cases the pulp has receded, when the teeth are less sensitive
to the test.
In spite of the limitations enumerated, the fact remains that the
electric test for determining the vitality of the dental pulp is by far the
best we have. Coupled with the use of radiographs it enables us to deter-
mine the vitality of the pulps of most teeth.
When testing a tooth with a proximo-occlusal or proximo-incisal
filling, or any filling passing beneath the gum margin, do not touch the
filling — touch the enamel only. When testing such teeth, two or more
396 APPENDIX
thicknesses of rubber dam may sometimes be placed between the filling
and the tooth approximating the filling. If kept dry, the rubber acts as
an insulation, keeping the current from passing into the approximating
tooth.
A tooth with a simple filHng, which does not come in contact with
the gum tissue or an approximating tooth, may be tested by touching the
dental electrode to the filling. When this is done, the current should be
weak.
The teeth being tested should be kept dry; with cotton rolls, if neces-
sary, otherwise the current will pass into the gums, pericemental mem-
brane and approximating teeth, through the saliva.
When the electric test is suggested most patients
EkCtropbObia. will offer some objection, saying they " can't stand
electricity." You will gain your patients' confidence
and co-operation by telling them that you can control perfectly the amount
of current used. Then prove this to them. Close the main switch, which
will start the mechanical interrupter and cause a humming noise. Throw
in all the resistance of the rheostat, or have the metal sheath clear in, and
say to the patient : " Now I am using so little current you will scarcely
feel it, if you feel it at all." Touch a tooth ; most any tooth except the
lower incisors. (The amount of current necessary to produce sensation
varies directly according to the size of the tooth. Thus, the patients would
be less likely to feel a weak current on an upper central or cuspid than
they would on the smaller teeth just mentioned.) With the current weak
the patients will not feel it or the sensation will be very slight and not
really painful. Now instruct the patients that you will use only enough
current to produce a momentary, warm, stinging sensation in the tooth,
and proceed to do so. As soon as you show the patients that you can con-
trol your machine, the dread of its use is practically gone. A good
psychic effect will be gained by calling the patients' attention to the fact
that you do not wish them to try to endure pain, but simply to let you
know as soon as pain is produced so you may stop it immediately.
A machine of the nature of the tester under con-
Ciability of JlCCident. sideration has an advantage over any switchboard
attachment or any machine deriving its electricity
from some powerful supply in that, in case of accident or improper use,
no serious accident can occur, because the source of electric supply, the
dry cell, is so small. One dry cell cannot produce enough electricity to
cause a serious or very painful accident. This should appeal to anyone,
but particularly to men whose knowledge of electricity is limited.
READING RADIOGRAPHS
397
The extreme value of the electric test for pulp
■^05^^447^ and B vitality can best be illustrated by recounting its use
in the following case: The end of the root of an
upper lateral was resected to cure an abscess. The wound made at the
time of the operation did not heal normally. A radiograph was made,
Fig. 447A. It seems to show that the central is involved in the lateral's
abscess cavity. The central was tested for vitality of its pulp. It re-
sponded to the electric test, indicating a vital pulp. Another radiograph
was made, Fig. 447B. This second radiograph, made at a different angle,
shows no involvement of the central, and what may or may not be an
involvement of the cuspid. The shadow passing to the apex of the cuspid
Fig. 447 A. The central incisor seem-
to be involved in the abscess.
Fig. 44 7B. Compare with Fig. 447A
of the same case.
Fig. 448. An abscess which seems to
involve both the lower first bicuspid
and the cuspid.
Fig. 449. A very small abscess of an
upper bicuspid.
does not show clearly. The cuspid was tested and its pulp did not re-
spond to the application of the current. It was opened and found to
contain a putrescent pulp. Neither the central incisor, at first suspected,
or the cuspid, finally opened, had carious cavities in their crowns. A
398 APPENDIX
satisfactory diagnosis in this case would have been impossible without
the use of the electric tester, as well as the X-rays.
Another case : Figure 448. From the appearance
Tifl, 44$, of the radiograph alone, one inexperienced in reading
radiographs would be likely to say that two teeth,
the lower first bicuspid and the approximating cuspid, are involved in an
abscess, since the evidence of bone destruction seems to include the apices
of the roots of both teeth.
However, the application of the electric test to the cuspid proved it
to have a vital pulp and treatment of the bicuspid alone effected a cure.
Case : The evidence of bone involvement at the
Tig. 449. apex of the bicuspid in Fig. 449 is so slight that a
definite diagnosis from the radiograph alone should
not be made. The appearance of the radiograph, coupled with clinical
signs and symptoms and the fact that the tooth did not respond to the
electric test, however, enables the diagnostician to state definitely that the
pulp in the tooth is not vital and that an abscess is forming.
41. To Make Radiographs of Every Tooth in the Mouth in
All Cases Where the Teeth Are Bei-ng Examined to Locate Foci
OF Infection.
In cases of arthritis, endocarditis, neuritis, gastritis, becteremia and
other " systemic " diseases, now attributed to focal infection, it is not
absolutely necessary to radiograph all of the teeth in all cases. Where
the test can be applied, the electric test for pulp vitality may be made and.
if positive, a radiographic examination is usually unnecessary, unless one
wishes to observe, for example, the extent of bone destruction, due to
pyorrhea. Thus the number of teeth which should be rayed may, in some
mouths, be greatly reduced. This is advantageous to the patient in that
the cost of the examination is reduced, and advantageous to the operator
in that he reduces the dose of X-rays. It is always wise to expose the
patient to the rays as little as possible, and likewise it is the sensible thing
for the operator, for his own welfare, never to Hght his tube unneces-
sarily. Regions from which teeth are missing should always be radio-
graphed to see that there is no piece of gum-covered root or unerupted
tooth. (See Appendix to Chapter VII under heading "Oral Foci of
Infection," page 416.)
In concluding this subject of radiographic misinterpretation, let me
repeat what I said at the outset lest I be grossly misunderstood : The
use of the radiograph is an absolute necessity in the practice of dentistry.
This extensive discussion of its shortcomings is, to the man who can see
READING RADIOGRAPHS 399
past his nose, a recognition of the fact that radiographs must be used.
It is not a harangue against their use, but an effort to stop their misuse
and abuse.
I realize that, in the foregoing rather exhaustive
Oral Toci of TnfCCtiOlU consideration of the interpretation of radiographs,
I have not answered, to the point of setting his mind
at ease, the man who is asking, " how to read radiographs " for the very
simple and apparent reason that the man who is asking " how to read
radiographs " not only wants to know how to interpret radiographs but
he also wants to know how to treat infection revealed by radiographs.
For the answer to this latter query it is a pleasure to be able to refer my
readers to such an excellent text as Thoma's " Oral Abscesses."
Allow me, however, to express myself briefly on this subject. The
radiograph gives a very good idea of the amount of bone destruction in
cases of dento-alveolar abscess and pyorrhea if intelligently interpreted.
The treatment indicated varies greatly according to the amount of bone
destruction. But granting that we know the exact amount of bone
destruction, different operators will always have somewhat different
opinions as to the course of treatment indicated. One operator will
excise the root end of an abscessed tooth, while another operator will
treat by ionization. Both operators may be able to overcome infection
in their respective ways. The treatment indicated depends not only on
the condition of the case to be treated, but upon the personahty and
ability of the operator. It is not good sense to assume that the same
treatment of an infected tooth is indicated regardless of the operator.
Some operators should extract teeth which other operators should save.
The object, when treating infected teeth and contiguous parts, remains
the same, namely, eradication of infection. Men of ordinary ability simply
cannot follow the methods of men of extraordinary ability. (Some
results of treatment of abscesses by forcing disinfectants through the
canal into the abscess area, by ionization and by root resection are illus-
trated in the Appendix Chapter XI, which will give the reader some idea
of what can be accomplished by these methods and so help him decide
which one to employ in certain cases.)
It is extremely difficult to say any definite thing which will apply
to all cases in a general way. However, I believe I am conservative when
I make this statement : If a tooth, showing bone involvement at its apex,
is to be treated through the pulp canal, the canal must be open through
the end ; it must be filled just to, or through, the end, and post-operative
400 APPENDIX
radiographs must be made at intervals of two or three months for about
a year, or until the abscess cavity is filled with new bone. An abscess
cavity which shows no constructive bone change at all at the end of six
months after treatment is very probably still a source of infection. As
a generality, it may be stated that if new bone ever will be built into an
abscess cavity, some reconstruction will take place within the first six
months or sooner, and the reconstructive change will be practically com-
plete in about a year.
What should be done with teeth, the canals of which are not well
filled but which show radiographically no bone involvement at their
apices? is a most disturbing question. The idealist's answer would be,
Fig. 450. Cement fillings.
" insert perfect canal fillings or extract the teeth." This advice may,
or may not, be good. The question is debatable, with everything in
favor of the idealist, however. But certainly, when a patient is very
seriously ill with some disease which might be attributed to a focus of
infection, all of the pulpless teeth in such a patient's mouth should, at
least, have a well-filled canal or they should be extracted.
It is not idealistic, perhaps, but it is practical, to be
'rfttidlfioM^' governed in the treatment of infected teeth by the
patient's physical condition. When the physical con-
dition is good, more conservative treatment can be given the teeth. When
the physical condition is bad and the patient is suffering from some
disease which may be attributed to mouth infection, more radical treat-
ment (freer surgical interference) must be given for mouth infection.
READING RADIOGRAPHS
K^ntblittd Discourse.
401
The writer filled canals in dissociated teeth with fif-
DO the UariOUS Canal teen different canal fillino- materials, most of them
Tflling materials . ^ ah % ^1 .11
Show in Radiographs ? proprietary pastes. All of these materials showed
in radiographs. One year later the teeth were again
radiographed and still all the different kinds of canal filling material
showed unchanged. Had the teeth been in the mouth, it is not impos-
Fig. 451. Case of antral empyema.
sible that some, at least, of the paste canal filling materials would have
sb.own some change one year after insertion. That the presence of most
402
APPENDIX
any sort of canal filling can be demonstrated radiographically imme-
diately after its insertion is a fact, but whether the various pastes, cement
and paraffin combination fillings can be observed some time after inser-
tion, is a matter as yet not definitely settled. The writer's experience at
Fig. 451A. The arrows point to a shadow which has the appearance of a tooth just starting
to form in the antrum. The shadow is caused by the dense bone along the lower border of the
malar bone.
this time leads him to believe that some cannot, which would seem to
indicate that they are not permanent.
Gutta-percha is a permanent canal filling which is always radio-
graphically visible.
Cotton with iodoform on it can be observed radiographically in
canals.
Paraffin, as a canal filling, unmixed with anything else, can not be
radiographed successfully.
READING RADIOGRAPHS
403
$i1iciou$ Cement
Tigure 450.
Silicious cement is more penetrable to the X-rays
than oxyphosphate of zhic, colorless copper or black
copper cements. (See Fig. 450.) The filling on the
extreme right is silicious cement.
Fig. 452.
Case of suspected frontal sinus or antral empyema,
incisor located.
An abscessed upper lateral
404
APPENDIX
To demonstrate the skill one may acquire from read-
€asc$ from Practice. ^^^? ^ great number of radiographs, observe Figure
451. It is highly improbable that one not familiar
with head radiographs will be able to observe anything of significance
Fig. 452A. From the time of the first acute attack, for four years, this tremendous dental
abscess had caused the patient no pain whatsoever.
in this plate, yet from a careful study of it, a diagnosis of antral empyema
was made, the verity of which was proved by operation.
Figure 452 was of a case of suspected antral or frontal sinus em-
pyema. The frontal sinuses show clear, and the antra are clear save for the
shadow cast over them by the petrous portion of the temporal bone.
READING RADIOGRAPHS
405
(Figure 452 was made from a pose with the head against the plate as
in Figure iii but with the X-rays directed diagonally forward from a
point just back of the base of the occipital bone. Such a pose gives a
very hazy view of the anterior teeth, a good view of the frontal sinuses
and a view of the antra obscured by the shadow of the petrous portion of
the temporal bone.) Observe a small spot at the apex of the lateral incisor
on the right. A small intra-oral radiograph was made and shows an abscess
cavity at the apex of this lateral. The patient would not consent to root
resection; the lateral was therefore extracted and the pus discharge
from the nose ceased. (See Figure 425.) The diagnosis in this case
Fig. 453. Diagnostic illuminating or view box, for observing X-ray negatives.
resulted from a thorough study of the large plate (Figure 452), in which
the suspicious area at the apex of the lateral was first observed. A care-
less, or thoughtless examination of the antero-posterior plate would have
resulted in failure to make the correct diagnosis.
CDronic 7lb$cc$$
and Pain.
It is a well-known fact among most dentists that a
chronic abscess may exist without causing any pain
or any local sensation at all for that matter. But all
dentists do not know this as well as they might, nor do near all
physicians ; and the public scarcely knows it at all. It is a fact which
4o6
APPENDIX
should be repeated again and again. I have seen a case recently with
half of the palatal portion of the superior maxillary bone destroyed,
the only symptom given by the patient being, " one side of the roof of
my mouth seems a little softer than the other." When explaining these
things to patients I have found that I can overcome incredulity by
Fig-. 454. Special dental view
box for observing small
X-ray negatives.
Fig. 4.55. Special dental device for observing dental X-ray
directing attention to the well-known fact that large parts of the lungs
may be lost from tuberculosis with little or no pain in the lungs. (See
Fig. 452 A.)
Figure 453 is a type of view box which has entirely
UiCW Boxes. replaced the type illustrated in Figure 122.
Special dental view boxes and illuminating
devices are illustrated in Figures 454, 455 and 456.
Dr, Edmund Kells, Jr., ofifers a scheme for marking
niarKing negatives, small film negatives for identification by punching
a small hole in the negative with a plate punch and
tying a string, with a small price-tag-like label on it, to the negative
which will certainly eliminate the possibility of " mixing " negatives by
getting the negatives from one patient's envelope into another patient's
envelope.
READING RADIOGRAPHS
407
I would earnestly advise that some sort of filing box
Tiling Boxes cr qj- cabinet be used by all who use radiographs.
Otherwise negatives will be lost or so chaotically dis-
tributed about the office that they can never be found when needed.
While it is true, in a general, inaccurate way, that
X-rays penetrate substances inversely in proportion
to their density, it is rather a loose way of stating the
action of the rays. Dr. Ottolengui has accordingly coined the following
words : Radioparent and radioparency, radiolucent and radiolucency,
Dr. Ottolengui's
new moras.
Fig. 456. Special dental illuminating device _ for displaying and observing dental X-ray
negatives.
radiopaque and radiopacity from the words transparent and trans-
parency, translucent and translucency, opaque and opacity. Thus we
might speak of a shadow in a radiograph something like this : " The
small radiopaque area is, I believe, a piece of tooth root." Or instead
of referring to a rarefied area at the apex of a tooth we would say:
"There is a radioparent or a radiolucent (depending on the degree of
X-ray penetration) area at the end of such and such a tooth."
It seems to me these words will prove to be most useful.
4o8
APPENDIX
O
^
^^
13
Chart A A
READING RADIOGRAPHS 409
Illustrating different sorts of canal fillings as seen in radiographs
The arrangement is somewhat in the order of the excellency of the
filling.
No. I. Canals filled full. Three apical foramina filled just through
the end of the root.
No. 2. Canal filled just through end. Auxiliary canal, to the mesial,
filled.
No. 3. Canal filling material encapsulating the end of root. We
see through the encapsulating material. When the material encapsulating
the root is thicker — as it usually is — the radiograph appears to show a
body of gutta-percha beyond the end of the root instead of a cap over it.
No. 4. Root end encapsulated and a little body of gutta-percha in
periapical space.
No. 5. Canal filling material through end of root and filling into
cancellous places in bone. More material through than desirable.
No. 6. Gutta-percha point passing through apical foramen intact,
differing from Nos. 3, 4 and 5 where mushy eucalyptopercha or chloro—
percha has " mushed " or " oozed " through apical end. Not so desirable
because perhaps apical foramen is not filled full — perhaps gutta-percha
point just passes through without filling the opening through which it
passes.
No. 7. Too much canal filling too far through apical foramen. In
this particular case, however, no evidence of irritation developed.
No. 8. The practice of filling abscess cavities full of the Callahan
gutta-percha-rosin mixture is being tried by some. The expediency of
this course has neither been proved nor disproved.
No. 9. This canal filling very probably reaches the end of the root
of the tooth, but we cannot be certain of this from the appearance of
the radiograph. We cannot be absolutely certain any canal filling reaches
the end unless a little passes through.
No. 10. These canal fillings very probably do not quite reach the
end of the root but we cannot be absolutely certain they do not.
No. II. The "cork screw" or "buckled" canal filling which does
not fill the canal solid full. ... A very faulty filhng.
No. 12. A filling of one gutta-percha point which neither fills the
canal full nor reaches the end of the root.
No. 13. A filling of one gutta-percha point which reaches well
toward the end of the root but does not fill the canal full. ... A very
faulty filling.
No. 14. A point inserted through a perforation between the roots
of a lower molar. We may have little respect for the operator's ability
who did this ; but he tried, and so we have more respect for him as a man
than for the operator with greater ability who doesn't even try.
4IO
APPENDIX
!
ir^
#
4.
4i
ii
B
M^
\l
Chart B B
READING RADIOGRAPHS 411
0bart BB
Illustrating different degrees of evidence of infection seen in radiographs
Nos. I and 2. No radiographic evidence whatever of infection.
The canal fillings are perfect as far as we are able to see and the bone
in the apical region has the appearance of healthy bone.
No. 3. No definite evidence of infection. However we cannot be
as certain that the canal is filled to the end as in the cases of Nos. i
and 2, where a little canal filling material passes through the end of
the root. There is no evidence of bone change in the periapical tissues.
No. 4. The only evidence of infection is the evidence that the canal
filling does not reach the end of the root. There is no periapical bone
change.
No. 5. Like No. 4, the evidence of infection is only the evidence
that the canal filling does not reach the end of the root. In this case
we see also the unfilled part of the canal standing open. Perhaps the
lumen of the unfilled part of the canal in No. 4 is very small, but we
know it is large in No. 5.
No. 6. Though the canal filling reaches well toward the end of the
canal, it does not fill the canal full and is, therefore, a faulty canal
filling. The only evidence of infection is the evidence that the canal
filling is imperfect.
Nos. 7 and 8. The canal fillings are imperfect and there is evi-
dence of bone change in the apical region. The evidence of bone
change — rarefication and sclerosis — is so slight that it would not be
looked upon as evidence of infection if it were not for the fact that the
teeth are pulpless and the canal fillings faulty.
No. 9. Definite evidence of bone destruction and hypercementosis,
both indicative of infection. However, the canal filling seems to be
perfect. The history of the case governs my opinion here. The tooth
has just been treated; there has been no time for bone reconstruction to
occur.
No. 10. The evidence of infection is quite definite ; canal filling
is faulty and there is destructive bone change in the apical region.
No. II. Definite evidence of infection, (i) faulty canal filling,
(2) bone destruction, (3) osteosclerosis.
412
f
APPEND
— -^^
2
3
4-
t
..:U
^^' '">*
^
s
I
i Pi C^4
Chart CC
READING RADIOGRAPHS 413
v,un
Illustrating how the radiograph helps the operator to determine the nature
of the treatment indicated
No. I. Considering the tooth involved and the sHght amount of
bone change, treatment through the canals would be the writer's choice.
No. 2. Different operators would disagree as to the treatment
indicated. Some would treat through the canals, others would resect
and curette. Certainly the resection-curettement operation is a more
reliable means of eradicating infection, but I have seen cases like No. 2
yield to treatment through the canals and show a bone reconstruction
following such treatment.
No. 3. Compared with No. 2, the resection-curettement operation
is becoming more imperative.
No. 4. Root resection is, I believe, definitely indicated here.
Nos. 5 and 6. Treatment through canals contra-indicated. Prog-
nosis for root resection, somewhat doubtful.
Nos. 7 and 8. Prognosis for root resection, very doubtful. Too
much bone destruction too far down on the mesial in No. 7, and too
much loss of osseous tissue at the cervical in No. 8.
No. 9. Prognosis for treatment through canals good, if the canals
can be opened to the end.
No 10. What the writer now considers as about the limit of the
extent of bone destruction at the apex of a molar which may be treated
successfully through the canals.
No. II. The number of teeth involved often governs the treat-
ment indicated. I should say, arbitrarily, extract the molars; treat the
bicuspid.
N. B. In the foregoing the writer has not taken into considera-
tion the physical condition of the patient. In practice this is a most
important factor.
414
APPENDIX
I
.:j>
T
7
Chart D D
WORKING DENTAL RADIOGRAPHS 415
0bart D D
Illustrating a number of different cases where extraction is indicated
No. I. The abscess is so large — i. e., there is such extensive bone
destruction — the case looks as though it might be syphilhtic, but is not.
Extraction of all the teeth involved was deemed the best procedure.
No. 2. So much bone destruction that treatment of any sort
calculated to lead to the retention of the tooth would probably fail to
eradicate infection.
No. 3. The bone about the distal root of the first molar is entirely
gone; the canal fillings in the mesial root are faulty and probably could
not be made perfect. (It is very difficult to open canals of molars to
the end when opening the tooth for the first time. When the canals
have already been partially filled by a previous operator, the chance of
opening such canals to the end is greatly lessened.;
Two perforations with canal filling passing through them in the
second molar.
Extraction of both first and second molars indicated.
No. 4. The first bicuspid is hopelessly diseased ; the bone de-
struction at the apex extends down along the sides of the root to the
cervical.
No. 5. The extraction of the central incisor is indicated because
there is so much destruction of its root that root resection would very
probably be unsuccessful.
No. 6. Only by extraction can the abscess, caused by the post
passing through the distal side of the second bicuspid, be cured.
No. 7. There were only ten teeth left in this mouth. All of them
showed bone destruction at the apex or at the cervical, or at both
places (the lateral).
APPENDIX TO CHAPTER VII
Uses of Radiodrapby in Dentistry.
The temptation to submit more radiographs to illustrate the uses
of the radiograph in dentistry is intense. I could now illustrate some
of the uses with better radiographs than are shown in Chapter VII, but
most of the uses are already sufficiently well illustrated to teach the prin-
ciple of the application of the radiograph, and that is as far as I should
go, otherwise there would be no limit to the number of radiographs which
might be shown, each having some interesting peculiarity of its own.
In other words, I will not attempt to exhaust the subject for reasons
so cleverly set forth in the following excerpt from " Life " : " Writers
should early learn not to try to exhaust a subject. If there is one thing
above another thing that a subject will not stamd for it is to be exhausted.
It is the one tireless thing extant. In every other way subjects are ami-
able and tractable. If you go at a subject in the right spirit you can say
nearly anything you wish about it, but immediately you try to get a rope
around a subject's neck and chase it around a ring until it is absolutely
used up, the said subject takes on a dry, dogged, stubborn air and re-
fuses to be interesting, and, of course a writer who cannot keep his sub-
ject interesting is lost.
" Think of the most uninteresting books you ever read. They were
written by men who quite evidently sat down with the mental resolution :
' Now I'll just clean up on this subject once for all, so that it will hence-
forth be clear to all posterity, even unto the day of judgment.' But, of
course, no such aim was ever realized. The only sure result of trying to
exhaust a subject is to prove that it is exhaustless."
The subject of the Uses of the Radiograph in Dentistry is certainly
exhaustless ; so I shall be satisfied to treat the subject in this appendix as
concisely as possible.
Perhaps the most extensive use of the radiograph
Tad ot Tnf^ction ^" ^^^ practice of dentistry today is as a means of
examining the mouth for infection in cases of bac-
teremia, arthritis, neuritis, endocarditis, gastric ulcer, appendicitis, en-
teritis, dermatitis, cholecystitis, nephritis and other constitutional dis-
eases ; also in cases of diseases of the eye, ear, nose and throat, which we
now believe may be caused by some focus of infection. For this purpose
the use of the radiograph is absolutely indispensable.
The practice of simply making ten film radiographic negatives and
416
USES OF RADIOGRAPHY IN DENTISTRY 417
then calling it a complete examination of the mouth is a much abused one.
Usually it is impossible to obtain good radiographs of all of the teeth
on ten negatives, and often it is not absolutely necessary to make radio-
graphs of all of the teeth. (It is sometimes more necessary to ray all the
teeth in other classes of cases, such as obscure neuralgias, for example,
than it is when the examination is made in a search for infection.)
It has been said that, in many cases where a search is being made
for oral infection, it is " entirely unnecessary " to radiograph all of the
teeth. I cannot agree that it is " entirely unnecessary," though it is very
often largely unnecessary. A radiodontist of keen judgment may elim-
inate certain parts of mouths from the radiodontic examination and not
make a mistake by so doing once in fifty cases, but the fact that it is
possible that he may make a mistake at all should keep us from condemn-
ing the practice of radiographing all teeth as " entirely unnecessary."
To make an examination of the mouth to determine whether or not
the teeth and jaws are a source of infection, the use of the radiograph is
only a part — true, the most important part but, nevertheless, only a part
— of the examination.
Careful ocular, instrumental and digital examination should be made.
Then the teeth should be tested for pulp vitality with the electric test and
records made of the result of these tests. Now radiograph, at least, the
following regions : ( i ) Regions from which teeth are missing, to locate
pieces of roots or unerupted teeth. (2) Teeth which do not respond to
the electric test and teeth which cannot be satisfactorily tested with the
electric test. (This always includes crowned teeth.) (3) Teeth af-
fected with pyorrhea, to observe the extent of the loss of osseous tissue.
(4) Any region of tenderness, localized pain or abnormal appearance.
An area of infection frequently overlooked is illustrated in Fig. 457
In a case such as Fig. 457, pus can often be pressed into view with the
finger, pressing with the index finger from below upward on the lingual
and just to the distal of the third molar. Because there is less distortion,
lesions like the one illustrated in Fig. 457 can be seen to better advantage
in extra-oral radiographs than in the intra-oral ones.
Dr. Risen makes it his practice to radiograph both sides of the mouth
on plates first, then re-ray on a film any suspicious areas found in the
plate if necessary to get a better view. This practice is certainly to be
commended.
I have made the statement repeatedly that an im-
cfifth pacted tooth may cause no trouble at all or it may
produce the most disastrous results. Allow me to
illustrate this : Figure 458A and 458B show two impacted upper cuspids
4i8
APPENDIX
in the same mouth. One (Fig. 458A) shows no evidence of pathologic
condition of the surrounding tissues while the other (Fig. 458B) shows
a great deal of bone destruction, due to suppuration. However, an un-
Fig. 457. The arrow points to a V-shaped area, indicating bone destruction back of a lower
third molar. (Eisen and Ivy.)
Fig. 458A and 458B. Unerupted cuspids, both in the same mouth, one causing much bone
destruction, the other none.
erupted tooth must be looked upon always as a source of possible sup-
puration, even when the radiograph shows no destruction of bone.
Unerupted Cuspid
made to €rupt.
Tid. 459a.
Figure 459 is the same case illustrated in Figures
150, 151 and 152 with the cuspid in its proper
place.
Never having seen the case illustrated in Fig. 207,
the writer certainly is not in a position to take issue
with Dr. Rhein, who treated the case, and Dr. Otto-
lengui, who wrote the history of the case on pages 195 and 196. How-
ever, I may say simply this ; the shadow over the cuspid illustrated
in. Fig. 207 has, to me, the radiographic appearance of being the antrum.
Figure 459A is a case having a similar appearance to Fig. 207. In Fig
459A I feel quite certain that the shadow over the cuspid is the antrum.
USES OF RADIOGRAPHY IN DENTISTRY 419
I can perhaps impress you with the value of making
Root Kw^Ctfon €a$($. radiographs before operating to excise root ends by
relating this experience. Dr. Carl D. Lucas, who
was to give a clinic on apical excision before the Indianapolis Dental So-
ciety, asked that a patient be selected for him from the Indiana Dental
College clinic. The demonstrators in the college clinic were advised of
this and asked to select a suitable case and send it to me for a radio-
graphic examination. Thus, the cases which came to me were those in
Fig. 459. The same case illustrated in Figs. Fig. 459A. The shadow of the antrum over
150, 151 and 152, after eruption of the the cuspid gives the cuspid somewhat the
cuspid. (Radiograph by Kells.) appearance of being abscessed.
which the symptoms were such as to indicate apical excision. Apical
excision was seen to be contra-indicated, however, in the first case, when
the radiograph showed the root of the tooth to be abnormally short; in
the second case, when the radiograph disclosed the presence of a perfora-
tion ; and in the third case in which the destruction of bone was too ex-
tensive. In the fourth case, the radiographic finding, indicated apical ex-
cision, thus finally substantiating the conclusions based on a knowledge of
symptoms. In the light of this unusual but instructive experience I would
insist that the operator should always make a radiographic examination
before operating to excise a root end.
Figure 460 shows a malposed, unerupted, partially
facial TfStU a €a$C$. formed upper second bicuspid. In this case the pus
discharged just beneath the eye. Removal of the
malposed bicuspid effected a cure. Figure 461 is a photograph of the case
one month after operation. (Operators, Drs. Page and Cofield.)
The use of radiographs in cases of fistulas pointing on the face is
attended almost always with the most gratifying results. While the radio-
graph will usually show some bone involvement in these cases it should
be remembered, however, that infection of the soft parts surrounding
420
APPENDIX
a lower third molar may result in the formation of a fistula on the face
with practically no bone involvement at all. Neither should one lose sight
Fig. 460. Malposed, unerupted, partially
formed upper second bicuspid.
Photograph of case.
Fig. 461.
Fig. 461. Post operative photograph of facial
fistula case. Scar under eye. See Fig. 460.
of the fact that an ordinary skin abscess — i.e., a boil — may have a clin-
ical appearance somewhat similar to an abscess of dental origin.
I have been surprised to find radiographs of
hidden Dental Canes, such value in locating hidden carious cavities in
TiflS. 462, 463 ana 464 ^g^^^
Figure 462 is a case in which the patient was suffering consider-
ably. The pain seemed to be localized in either the second bicuspid or
the first molar. The radiograph shows nothing wrong with the second
bicuspid, an abscess at the mesio-buccal root of the first molar and, most
important of all from the standpoint of relieving pain, a carious cavity
in the distal of the second molar. The cavity was entirely covered with
gum tissue, When access was gained to it, it was found that the pulp was
exposed. A sedative treatment was applied and pain was relieved
immediately.
Figure 463 shows caries at the cervical margins of the fillings in the
distal of both the first and second molars. Such cavities as these are very
seldom found at all unless located radiographically. (In this particular
case, Figure 463, both of the molars are abscessed.)
The history of Figure 464 is rather long but quite interesting. A
man of middle age, multimillionaire, awoke one morning with the tooth-
USES OF RADIOGRAPHY IN DENTISTRY
421
ache. Straightway he visited a dentist, who examined his mouth, told
him there was nothing the matter with his teeth and that he had neuralgia.
The patient, still believing he had toothache, visited another dentist who
examined his mouth and told him in substance the same thing. And the
patient who still believed he had the toothache visited a third dentist who
Fig. 462. Gum-covered carious cavity
distal of upper second molar.
40.'!. Fillings failing at the cervical
margin.
Fig. 464. Hidden carious cavity in distal of lower first molar.
like the others, examined his teeth and told him his teeth needed no treat-
ment. In despair, since his dentists had failed him, the man next visited
a bar-tender and then another bar-tender, and another, and another, until
his friends took him to the hospital that he might recover from delirium
tremens. In due time he recovered from his delirium and as soon as he
did, he complained of the toothache. A dentist was called in. He ex-
amined the mouth and found nothing wrong with the teeth. It happens,
however, that this particular dentist is a radiodontist of no mean ability,
and, so he asked to be permitted to make a radiograph of the region where
the pain seemed to be located. This was granted promptly — though at the
time all this occurred very few radiographs of teeth were being made
— for the physicians in charge of the case were helpless.
Figure 464 was made and shows a carious cavity in the distal of a
lower first molar ! The case was simply one of pulpitis ! There are doubt-
422 APPENDIX
less those who will say that the cavity should have been discovered
without the aid of the radiograph, by instrumentation. Perhaps, but, the
fact remains, it was not. And so impressed were the medical men with
Fi?. 4(;r). Slight destruction of osseous tissue
in apical region of lower first molar follow- Fig. 4(i(;. Case in which the patient suffered
ing use of arsenic. from attacks of sneezing.
the dentist who finally made a diagnosis and cured the patient, they put
him on the hospital staff, a member in full standing; a thing that had
never happened to a dentist in that city before.
Figure 465 illustrates a slight bone destruction at
CbC €ffCCt Of Jlr$cniC. the apices of the roots of a lower first molar imme-
diately following devitalization of the pulp with ar-
senic. However, I cannot state definitely that the slight bone destruction
is not due to infection, for I do not know in detail the conditions under
which the work was done.
Symptoms : Periodic sneezing attacks. The radio-
Ucry Unusual Ca${. graph (Figure 466) shows an abscess of an upper
central incisor, communicating with an abscess
sinus in the apical region of the extracted lateral. Up to the present
time, I have been unable to hear from the case since the radiographic
examination, but I feel quite certain the condition of the teeth could be
responsible for the sneezing attacks.
It used to be the writer's opinion that a piece of root
Pieces of toOtb Root, would always " work " to the surface of the gum in
time. Radiographic experience is teaching me, how-
ever, that not infrequently the gum heals over tooth roots and they remain
in the jaws for years without appearing at the surface of the gum tissue.
Such roots are usually a source of irritation and infection, though not
always. .
APPENDIX TO CHAPTER VIII
Cbc Hnmr of tbe X-Rays.
The following- factors must be considered when determining the dose
of the X-rays : (i) The time of exposure. (2) The milliamperage passing
through the tube. (3) The distance between target and skin. (4) The
action of a filter. (5) The quality of the X-rays. (6) The temperature
of the X-ray tube, (7) The kind and working condition of the X-ray
machine. (8) The sensitivity of the skin exposed.
It will be seen from the foregoing that the problem of administering
exact doses of the X-rays is one fraught with great difficulties. It is
the writer's opinion that general practitioners of dentistry and medicine
should not use the X-rays for therapeutic purposes unless they are willing
to give the matter the great amount of study necessary to enable them
to administer definite doses.
It is the writer's further opinion that both the general practitioner of
dentistry and medicine may find it to their advantage to use the X-rays
for radiographic purposes. When using the X-rays for radiographic
purposes it is not necessary that the operator know all there is to be
known about dosage. He should, however, know enough so he will not
expose his patients to the point of producing dermatitis.
It is with the idea of imparting only such knowledge as will enable
men to practice radiodontia without danger of producing X-ray derma-
titis that we take up a consideration of X-ray dosage. Only the most im-
portant and most variable factors governing dosage will be considered.
The efifect of the X-rays on the skin varies di-
andmfuiamu^raat rectly according to the length of time of exposure ;
thus, other things remaining the same, the effect is
twice as great if the exposure is two seconds as it would be if the ex-
posure were for one second.
The effect of the X-rays on the skin also varies directly according to
the number of milliamperes passing through the tube ; for example, other
things remaining the same, 10 milliamperes produce twice the effect pro-
duced by 5 milliamperes.
To obtain the same effect on the skin as the time is lessened the milli-
amperage must be increased, or as the milliamperage is lessened the time
must be increased. For example, 10 milliamperes for 6 seconds will have
practically the same effect as 6 milliamperes for 10 seconds. In other
words, the milliampere-second dose is the same, i.e., 60 milliampere-
423
424 APPENDIX
seconds. The milliampere-second unit is obtained, recall, by multiplying
the number of milliamperes passing through the tube by the number of
seconds exposure.
Though it would not do for the X-ray therapeutist, the milliampere-
second is perhaps the best unit of measurement of X-ray dosage for the
radiographer.
The effect of the X-rays on the skin varies in-
'St^il^llfliPilM.tS" versely with the square of the distance or, to state
varget ana Skin. , -^ , . ,...^ , . , , . ,
the same thing diiierently, m order to obtam the same
effect on the skin the size of the milliampere-second dose varies directly
with the square of the distance. To elucidate : The dose necessary to
produce erythemia of the skin of the face with the skin-target distance
8 inches is about i2ck) milliampere-seconds. With the skin-target dis-
tance increased to i6 inches the erythemia dose is about 4800 milliampere-
seconds. This conclusion is reached as follows : the square of 8 is 64,
the square of 16 is 256, 256 is four times as much as 64. Therefore, the
dose at 16 inches is four tim.es as much as at 8 inches, for the dose neces-
sary to produce the same effect varies directly with the square of the
distance.
The use of a filter of one millimeter of aluminum
CbC filter. necessitates doubling the dose to get the same skin
effect.
We are now ready to consider a limit of the dose
''^"of Patfcntr"'*^ °^ X-rays to be given to radiodontic patients. I
would suggest that operators never exceed one-half
the erythemia dose.
Suppose now, for example, that the distance between the target and
the skin is 16 inches — which is, however, probably greater than the
average distance for radiodontic work — and no filter is used ; do not ex-
ceed what I shall call the safe dose of 2400 milliampere-seconds (4800
milliampere-seconds is the erythemia dose, recall).
If the distance is only about 8 inches between target and skin —
which perhaps is a little nearer the average distance for radiodontic work
as practiced — then do not exceed the safe dose of 600 milliampere-seconds,
unless a filter of one millimeter of aluminum is used, when the dose may
be doubled, that is made 1200 milliampere-seconds.
If a full safe dose is given wait two weeks or a month before making
any further exposure and so guard against a cumulative effect.
Making radiographs of one side of the mouth has, of course, very
little effect on the skin of the other side of the face.
THE DANGER OF THE X-RAYS 425
Suppose now we take a case from practice and see how a man would
figure his dosage. He makes measurements and finds the distance from
target to skin to be 12 inches. The safe dose at 8 inches is 600 milliam-
pere-seconds. Apply the rule now that the dose may be increased directly
with the square of the distance. The square of 12 is 144, the square of 8
is 64; 144 is 2^4 times as much as 64. Two and one-fourth times 600
milHampere-seconds equals 1350 milhampere-seconds.
Without going into a detailed description of " the
^tif''i»^'^*'^ why and the wherefore " of the fact, it may simply
be stated that it requires a greater skin- dose of
X-rays to make a radiograph with a very small X-ray machine than
it does with a medium or large machine. Hence the number of radio-
graphs which can be made with safety varies somewhat with the size of
the X-ray machine. With the smaller machines fewer radiographs can
be made without exceeding the safe dose.
Men with small machines should be particularly careful, or they
will exceed the safe dose and may produce dermatitis. Likewise men
who employ the " soft tube technic " must remember that the low vacuum
of the tube necessitates a greater millianpere-second exposure. Dr. Geo.
M. MacKee* reports having seen, " in sixteen months, eight cases of
radiodermatitis," i.e., X-ray burn, which were produced incident to
radiographic examination of the teeth.
Dentists must equip themselves with the right kind of machine, and
they must know how and must keep tab on their dosage if they expect
to do much radiographic work. It is dangerous to attempt to examine
all the teeth in a mouth with a small X-ray machine, then follow this with
re-examinations as canal work is being done, unless the operator keeps
careful track of the dose he is giving and stops when he reaches the safe
dose limit.
Many dentists who are doing all of their own X-ray work should
either get bigger machines and use them more intelligently or they should
refer most of their work to specialists and do only the simpler, easier
work themselves.
As long as the fee for dental radiographs remained
TnflMCnce of Tecs high the probability of excessive dosage due to
the making of many radiographs was not great.
But, as more of the work is being done, the fee is getting so low
in many localities that it no longer offers the protection it once afforded.
* Dental Cosmos, May, 1916.
426 APPENDIX
but becomes instead the chief factor in the development of careless, dan-
gerous practices.
As stated in Chapter VIII the first rule regarding
Ch^CkCtrlC test for the exposure of patients is not to expose them any
longer than necessary. Conscientious and consistent
use of the electric test for pulp vitality will cut down the number of radio-
graphic exposures necessary, especially in cases where the entire mouth
is to be examined in a search for infection, and it should therefore be
used.
In the past the writer has been a conscientious advo-
0arck$$llC$$ and ^ate of the belief that the dentist should do at least
Ignorance*
a part of his own radiographic work. But, as dentists
commence to take up the work now, I am appalled at the degree of igno-
rance and carelessness displayed. Unless I can see some evidence of
study of the subject before long, I shall be forced to conclude that radio-
dontic work should be done only by a few men who have the ambition
to do it as it should be done.
I feel safe in predicting that, unless intelligence is soon displayed
by dentists, a wave of disaster from X-ray lesions will sweep the country,
leaving more victims than was claimed by the X-rays directly after they
were discovered. These victims will be both dentists and dentists' patients,
to the best of my ability to judge, mostly the former, for most dentists
seem to fail utterly to appreciate the necessity of protecting themselves.
It was learned from disastrous experience that the operator should
have protection. Protection was accordingly given and because this pro-
tection has proved effective the tendency among even the best X-ray men
seems to be to dispense with as much of it as possible. This tendency car-
ried too far will result in disaster. There is every reason in the world
why the operator should have protection and practically no reason, unless
inertia may be considered a reason, why he should not. I earnestly advise
the use of the lead screen or cabinet by all operators.
Some men make it a practice to hold the film in the patients's mouth
during its exposure. This is positively unnecessary and, if the practice is
continued, is certain to result in injury to the operator.
Other operators have their assistant hold the film in the patient's
mouth during exposure. This is worse than for the operator to hold it, for
it is less fair and less humane, and also it may prove to be very expensive
in case the assistant receives a burn and brings suit under the " employer's
liability and compensation law " such as we have in many different States.
As I have said elsewhere, properly handled the X-rays are harmless,
THE DANGER OF THE X-RAYS 427
so harmless that the tendency is to cease handHng them properly when
they may become woefully harmful.
n^-.u.*. -nu...* Since the effect of the X-rays varies inversely with
roiitis Jibout , . , , . ... -^ , .
Protection of the square 01 the distance it is quite apparent that it
Operator. jg advantageous, as a means of protection, for the
operator to be as far away as possible from the tube while it is in opera-
tion. A foot switch (Fig. 467) or any other form of extension control
Fig. 467, A foot-switch by means of which the operator may stand any desired distance from
the X-ray machine and tube when the current is turned on.
leading from the machine may be used to enable the operator to increase
the distance between himself and the tube. It is common and good prac-
tice to have the X-ray machine controls mounted on a stand back of the
screen or on the back of the l^ad screen (Fig. 468). Wires lead from
the X-ray machine to the screen, which wires may be made of any desired
length and so the operator may stand as far away from his tube and
machine as the size of his room will permit. Also the controls may be
mounted on the X-ray machines and, by means of an overhead wiring
system (Fig. 361), the tube removed any desired distance from the
machine.
The operator should not only make it a rule to stand as far away
from the tube as possible while it is in operation, but he should always
see to it that the active hemisphere of the tube presents away from him,
and incidentally I may say also away from his supplies of films and
plates.
Figure 83 shows a protection cover for the top of lead glass bowls.
I wish to modify the remarks on page 278 referring
Hlopecia. to the possibility of baldness being produced in oper-
ators due to the continuous small dose of X-rays they
unavoidably take.
Recent experiences and observations lead me to believe that X-ray
operators not infrequently lose hair due to the action of the X-rays.
APPENDIX
Fig. 468. A movable pedestal with " controls " mounted on it.
THE DANGER OF THE X-RAYS
429
Figure 469A shows alopecia in a patient following radiographic
examination of the frontal sinuses and antra. Figure 469B is the same
case about three months later showing a new growth of hair.
I know so little of the history of this case I shall not attempt to give
it further than to say that there was never any dermatitis.
I shall instead give the history of a similar case encountered in my
own practice ; of which unfortunately I do not have photographs. Patient :
Fig. 469A. Case of alopecia produced in ef-
fort to make antero-posterior radiograph of
the antra.
Fig. 469B. Same as Fig. 469A about three
months later, showing new growth of hair.
Male, age 30. Blonde, fine, thin hair. Repeated exposure for frontal
sinus examination netting a dose of about 900 milliampere-seconds in
three days, distance between target and skin about 9 inches, no filter used.
About one month after exposure the hair commenced to come out of the
region of the head exposed, continuing to come out for about two months,
at the end of which time the head was quite bald. Almost immediately
then the hair commenced to come in again and conditions were normal
once more at the end of about two more months. There was never any
dermatitis.
I have received several similar histories from various men. In one
case the hair commenced to fall out 3 days after exposure and the patient
was bald in about 10 days, but in this case, as well as all others, it came
back.
The tendency is to say that " the hair comes back thicker than ever,"
but this is hardly the case. However, the hair does come back as thick
as ever.
This accident of producing alopecia for a young lady patient would
be extremely distressing to both patient and operator. I advise the use
430 APPENDIX
of a filter of i millimeter of aluminum or a piece of sole leather for
antrum and frontal sinus cases to guard against such an accident.
Let us compare the currents of X-ray machines to the
r'i.55!!^^'!.5L^* current used for electrocution and so get some idea
of the danger of the former. J:* or electrocution at
the Ohio State Penitentiary the current used is 60 cycle A. C, voltage
1700 to 2500, amperage 4 to 6 for one minute.
It will be seen from this that the current of X-ray machines is never
very similar to the electrocution current. The current of the primary
is higher in amperage but much less in voltage ; the current of the sec-
ondary is higher in voltage but much lower in amperage.
Of course one should avoid coming in contact with the wires of
either the primary or secondary of any X-ray machine, for the shock
may be either painful or possibly even result in injury. The sensation
when receiving a considerable quantity of electricty is that of a " jolt."
The " jolt " or blow may knock the victim down, and so this usually
breaks the circuit, but if it should knock the unfortunate one onto, instead
of ofif of, the " live " wire, the injury might be great.
There is very little danger of receiving a shock from the primary
circuit, but both the operator and the patient sometimes inadvertently
come in contact with or in too close proximity to a secondary terminal.
Contact with a secondary terminal means anything from an unpleasant
experience to a disastrous one, depending largely on the size of the
machine. When one gets very close to — within one or two inches — but
does not come in contact, with a secondary terminal a spark may jump
from the terminal. This is of course unpleasant and may cause inflam-
mation of the skin at the point of entrance of the spark. See Fig 102,
which illustrates how the patient may be protected when it is necessary
to bring a terminal close to the body.
APPENDIX TO CHAPTER X
Stereoscopic Kadiograpby.
Some improvement in dental stereoradiographs has been made in the
past five years but the full possibilities of this process have not yet been
developed.
The idea of enlarging dental stereoradiographs was given in Chapter
X, Figs. 350 and 354. In pursuance of this same idea it is the writer's
practice, in some cases, to enlarge stereoradiographs as in Fig. 470. The
enlargement is made on a plate — not paper — and observation of the
stereoradiographs is made with a stereoscope like the one illustrated in
Fig. 323. The result is sometimes very gratifying. In the case of Fig. 470,
for example, it enabled me to state definitely that the unerupted cuspid
lay to the labial of the lateral incisor root, a fact which I had failed
to determine, to my complete satisfaction, by ocular and digital examina-
tion of the mouth, observation of single radiographs, and observation of
unenlarged, stereoradiographs.
This method is too new for me to hazard an opinion of its value, but
I can say conservatively that it seems to hold the greatest possibilities
of any method thus far tried by me.
The technic outlined in Chapter X, that which is
tCCbttiC* applicable to all stereoscopic work, is followed.
The film-holder, Figs. 331, 332 and 333, is used, if
possible, to insure placing the film packets in the mouth in the same posi-
tion for the two exposures. If the film-holder cannot be used simply
place the two film packets in the same position to the best of your ability
to do it, having the patient hold the film with the thumb or finger, or place
the film in the mouth as in Figs. 96 and 103. (See text on page 311.)
Hold the head immovable by using a device similar to Fig. no or
with the patient in a sitting posture by bandaging the head to the head
rest.
Make the two exposures, shifting the tube as di-
markiltd ncgatiOCS. rected in Chapter X. While in the dark room, be-
fore proceeding with development mark the films
right (R), and left (L), the operator imagining himself in the position
of the tube at the time of exposure and that one exposure has been made
for the right eye and the other for the left eye. Films may be marked
for identification by placing a small " R " and " L " in the corner, making
the mark with a lead pencil (this mark can be seen after the negative is
made) or by punching small holes in the corner of the film with a plate
punch, making one hole for the right, two holes for the left.
431
432
APPENDIX
Fig. 470. Dental radiograph enlarged for observation in large stereoscope.
STEREOSCOPIC RADIOGRAPHY
433
The next step is enlargement. This the operator may
Gnlaraemcnt have done for him by any photographer or he may
do it himself, using the usual photographic enlarging
apparatus, which consists of a light back of the negative, from which the
enlargement is to be made, shining through the negative and an enlarging
lens onto a standard which holds the photographic plate or paper (in
this case a plate) on which the enlargement is to be made. (See Figs.
471 and 472.) The negative to be enlarged is placed with the coated side
away from the source of light. Enlarge to the size of Fig. 470 or larger.
Fig. 471. Enlarging apparatus.
^, , -, Observe enlargements by means of a stereoscope
Observation of en- ,., _. v. 1 .li 1 i. r ^u
largCd StmoradiO- like Fig. 323. By placing the enlargement from the
graphs* right negative on the right side of the stereoscope,
the left enlargement on the left side, with the coated sides of the plates
toward the light of the illuminating boxes, the operator makes his ob-
servation from the position of the film at the time of exposure. By re-
versing the negatives as they are placed on the stereoscope — i. e., by
placing the right enlargement on the left side of the stereoscope and the
left enlargement on the right side of the stereoscope, with the coated sides
of the negatives still toward the light of the illuminating boxes, or by re-
versing the negatives so their sensitive sides present away from the light
of the illuminating boxes toward the operator's position of observation
but allowing the right negative to remain on the right side and the left
on the left side — the position from which the operator makes his obw
434
APPENDIX
servation is changed from that of the film during exposure to the position
of the X-ray tube during exposure.
The foregoing statements regarding the mounting of negatives on
the stereoscope for observation, and the possibihties of changing the
operator's position of observation thereby are difficult to follow. I would,
therefore, advise those who wish to take up this work to make test or
experimental cases by stereoscopically radiographing the hand with a coin
Fig. 472. Enlarging apparatus.
on it, carrying the hand radiographs through the process of enlargement,
and then observing them in different ways in the stereoscope.
As I have stated elsewhere stereoscopic work, be-
fl|)Dlicatlon Of tbC$C cause of its difficulty will remain principally in the
mctbods to Dentistry. ■ v ^ ^u ^ ^ i •
hands of specialists, ihe practice of making en-
largements renders dental stereoscopic radiography a definite success
in cases where heretofore it has been a failure. Stereoscopic work remains
too expensive to come into general use, but for those who can afford it
the service is worth the fee which must be charged for it.
I have heard the statement made repeatedly that the two negatives
which are exposed simultaneously in the same film packet can be mounted
and observed with a stereoscope, and that a stereoscopic effect is obtained.
I may be compelled to change my mind sometime but right now I may
STEREOSCOPIC RADIOGRAPHY
435
say I don't believe it. At least / cannot observe the parts perspectively
with such negatives and I am inclined to think that the imagination of the
B^PLATE
Fis. 473. Drawing wliich shows how the size of the object being radioRraphed may be
increased by moving it away from the photographic plate toward the X-ray tube.
Fig. 474. The Ketcham stereoscopic film-holder.
operator is responsible for any stereoscopic effect obtained from such
negatives.
436 APPENDIX
It will be noticed in Fig. 351 that the coins shown are of slightly dif-
ferent sizes ; they are, however, all of the same denomination and so the
same size. The reason for the apparent difference in size is illustrated
diagrammatically in Fig. 473 ; as the coin is moved away from the plate
toward the target the shadow of it cast on the plate gets larger. Fig. 474
illustrates the Ketcham film-holder for stereoscopic work. The face
is marked so the holder may be removed and re-inserted in the same
position.
CHAPTER XI
Cbe Problem of Pulp €anal Surgery and Oral Tnfectloti.
Before we can proceed with a consideration of the
Bad 0anal morK. problem of pulp canal work, we must agree that there
is such a thing as " bad canal work " — i. e., canal
work which fails to eradicate, or prevent, the formation of local foci of
infection at the apices of the roots of the teeth. In fact, most canal work
is of this kind. I state this dispassionately as a fact, not with the
spirit of reprimand and, I would have you know, I do not believe " the
canal work of the dental profession is a disgrace." It may be a mistake
but it is not a disgrace. Muriel Strode says, " It is no disgrace to wear
rags ; the disgrace lies in continuing to wear them." Likewise, it is no
disgrace to make a mistake ; the disgrace lies in continuing to make the
same mistake.
If there is any one who still believes that it has been
Tailure to Till Canals the practice of dentists, in the past, to fill canals,
^jjilj^ even large canals, to the end of the root, look at Fig.
475. The radiographs shown in this illustration
were obtained by giving an office assistant in a radiodontist's office these
instructions : " Go through the H's in- the little file of old negatives and
select all the cases showing canal fillings in any teeth except molars."
Figure 475 shows forty-eight teeth (none of them molars) in which
there has been an effort made to fill the canals. Forty-seven are failures
so far as success in reaching the end of the roots is concerned and most
of them show evidence of osseous infection at the apices. One, an upper
first bicuspid, filled recently under the writer's directions, shows the canal
fillings encapsulating the ends of the roots, and so we shall call this a
success from a mechanical standpoint at least.
It is a fact then that it has not been the practice of
KadiOflrapbS dentists to fill the canals even of anterior teeth and
Canals Of tectb. biscupids. We need not consider the question of
whether or not it is possible to " fill the canals of all
molars to the ends of the roots " just now. Let us stick to the problem of
filling the larger canals of teeth other than molars. No one will deny the
437
43S
APPENDIX
Fig. 475. Forty-eight teeth, other than molars, where efforts have been made to fill canals.
The canal filling material fails to reach the end of the root in forty-seven out of the forty-eight.
These teeth were selected at random.
CANAL SURGERY AND ORAL INFECTION 439
physical possibility of filling the canals of the teeth referred to above —
except in a very few anomalous cases — and no one who has observed a
considerable number of radiographs, will deny the fact that it has not
been done, and no one, who has commenced to " check up " his root canal
fillings with radiographs, will deny the additional fact that the canals of
Figs. 476, 477 and 478. Repeated efforts to fill the canal of an upper central incisor. Note
the little canal leaving the main canal, to the mesial, at riglit angles, in Figs. 477 and 478.
teeth never will be filled until radiographs are used to show the operator
when he succeeds in placing his canal filling to the end of the root and
when he fails.
One of my friends says : " The great trouble in filling
fft'rfll raiiaU canals arises from the fact that the canal filling
material doesn't go where you put it." And so it
seems, indeed, when one commences to radiograph his canal fillings.
You will place a canal filling in a single-rooted tooth and, before radio-
graphic examination be willing to swear you have placed it to the end of
the root, only to learn, after radiographic examination, that you have not.
Figures 476, 477 and 478 illustrate repeated efforts to fill the canal of
a central incisor. This was done by an operator of unquestionable ability.
Figure 476 illustrates the result of the first effort. The second effort is
not illustrated — it had the same appearance as Figure 476. Figure 477
illustrates the result of the third effort. Note that, even though the
operator is using force enough to send his canal filling material off into
a canal which leaves the main canal almost at right angles to the mesial,
still the main canal is not filled to its end. Figure 478 illustrates the
fourth and successful effort to fill the canal to the end.
440 APPENDIX
Let us not waste time blaming anybody for what we
andll^iu "°^ ^^^^ ^^^ canal work, for nobody is to blame.
The only men who deserve condemnation for the
work they have done in the past are those who have made no effort to
fill canals. Until recently canal work was considered successful, by
dentists, physicians, scientists and the public, if it prevented subsequent
toothache, and, measured by this standard, the canal work of the dental
profession has been a success But the extensive use of the radiograph
and the theory of mestatic infection set a new standard: Pulp canal
work must not only prevent subsequent toothache, it must also prevent
subsequent periapical infection. Methods which fulfill the requirements
of the old standard fail to meet those of the new, so they must be dis-
carded and replaced by methods which do eradicate and prevent the
development of foci of infection.
The answer to the question : " What shall we do about our canal
work? " is, we shall do better canal work and we shall do less canal work.
We must practice the sort of canal work advocated by Callahan, Otto-
lengui, Rhein, Best, Biddle and other leaders in this work. But before
we can adopt what we know to be the best methods in canal work we
must educate the public to the point where they will readily permit us to
practice such methods, and as we do this we will incidentally educate
people to co-operate with us to prevent the necessity of canal work. Even
the best methods in canal work can be and will be improved upon, but
just at this time it is not common for dentists to make a practical appli-
cation of the knowledge we already have on this subject.
I refrain, then, just now, from a consideration of the technic of better
canal work, recognizing the fact that it has already been given to the pro-
fession time and time again, but it has not been accepted because economic
conditions have made its acceptance impossible.
The average dentist today occupies a rather difiicult
Hocraac ricntist position. As Dr. Harry Carr facetiously expresses
it, " If he does his canal work as he has been doing
it, he gives his patients heart trouble. If he takes the time necessary,
and does it as he now believes it should be done he gives them heart
failure — when he presents his bill." This is funny because it is so
pathetically true. Fees for canal work which has for its aim only the
prevention of further toothache are only about one-fifth the amount which
must be charged for canal work which is calculated to prevent subsequent
periapical infection. Yet the fact remains, the more expensive methods
must be adopted and practiced by all ethical dentists.
CANAL SURGERY AND ORAL INFECTION 441
" But how ? " cries the average dentist. " I cannot do this work
unless I am paid for it, and my patients either will not or cannot pay me."
The patient who could but will not pay for good canal work gives me
little concern. Such a patient is either impervious to reason or he or she
has not had the matter presented in the proper light.
But patients who actually cannot afford the work (and there are
thousands upon thousands of them) do give me much concern. Many
people cannot afford good canal work because they need so much of it.
If they had less of it to be done they could afford it. And, note this :
it is important. Canal work becomes necessary when a tooth aches, and
most toothache is preventable.
And so we arrive where every thinking man arrives
^^Cca^^Us*^'"^ ^^ ^^ gives this problem of canal work sufficient con-
sideration. We see that something must be done to
prevent conditions which necessitate canal operations. We arrive at this
conclusion if we consider the problem from a financial aspect, as I have
just considered it; we arrive at this same conclusion if we consider the
disasters of poor canal work or the difficulties or shortcomings of the
best canal work ; and we arrive at this same conclusion if we consider the
unnecessary pain suffered and the waste of time and energy.
Something must be done to prevent conditions which necessitate canal
work. That is, something must be done to stop the practice, common with
most people, of deliberately allowing their teeth to ache before patronizing
a dentist, instead of visiting him periodically and allowing him to fill and
refill their teeth as soon as cavities appear and so prevent the occurrence
of toothache and the necessity of canal operations. Figure 479 illustrates
this idea of pulp conservation and prevention of toothache.
The thing which must be done is to educate the people to a better
understanding of the folly of allowing their teeth to ache.
It would take years to accomplish this by lectures, tracts, magazine
articles, newspaper articles, and personal advice. But it can be accom-
plished in twenty-four months by a publicity campaign conducted by the
National Dental Association,
Since we contemplate educating the public it might
6dMStk>n'flJ»0CateS ^^ ^^^^^ ^° ^^°P ^""^ consider some of the character-
istics of our prospective student that our efforts at
teaching may be governed accordingly. The public is a big lazy, indif-
ferent duffer, unwilling to learn anything. To teach him, you must
442
APPENDIX
Canes
(UGcay^
J^estorat/On
Canes
li'estorat/oti A/gw J^ostorat/on
Pulp
From
Where Puljo Has f^&cedGcf
/^GStorat/o/7
Canes
/\ge Of
Patient
/O Years
/ige Of
^ Patient
30 Years
\ ^at/erit
35 Years
Note the
r/7J/ng/\io\^
^EntGrsThat
)PartofThoth
Where Pu/p
Used to be.
But Has
j F^eceded.
Prom Where
Pulp Has
I^ecec/Gd
A/ew ^Restoration
Enters Tooth to
GreatDGpth Without
I^each/ng Pulp.
Fig. 479. A schematic drawing to show how teeth may be taken care of in such a way as to
avoid the necessity of pulp canal work. (Drawing by W. O. Godwin, junior dental student,
1917.)
CANAL SURGERY AND ORAL INFECTION 443
amuse him, arouse his curiosity, scare him, or make the lesson so easy
that it can be learned without effort. It should be borne in mind, also,
that the public has a thousand or so other teachers besides us annoying
him. The socialist wishes to educate him to save him from capitalism ;
the capitalist wishes to educate him to save him from socialism ; the
minister wishes to educate him in right conduct to save his soul ; the
physical culturist wishes to educate him to save him from physical deterio-
ration ; the sex hygienist wishes to educate him to save him from syphilis
and gonorrhea, and so on and on. No wonder he is lazy and indifferent
He has to be in self-defense.
If you accept my picture of the public as a student, as I have drawn
it, you will agree with me that it is useless to attempt to teach him a long
lesson. It would be futile to attempt to teach him this, for example :
" Toothache can be avoided.
" It can be avoided if you will visit your dentist at regular intervals
and have him fill and refill your teeth as soon as cavities occur.
" You should avoid toothache.
" Because, to commence with, who wants to suffer with the tooth-
ache, anyhow ?
" Because a tooth which has ached must be treated.
" Because the treatment of teeth takes much of your time, and your
time is valuable.
" Because the treatment of teeth by modern methods is very expen-
sive. (In fact, toothache and the treatment it necessitates is a luxury to
be indulged in to any great extent only by the well-to-do.)
" Because once a tooth is allowed to ache, there is the chance that
you may lose it, and you need all the teeth you have.
" And because, unless a tooth which has once ached is properly
treated, it may later ruin your health and life by causing rheumatism,
heart trouble, gastric ulcer and other serious diseases.
"So
" You mustn't let your teeth ache."
I would like to teach all of the foregoing to the public, and, if I could,
it would be the nearest thing to a solution of the problem of canal work
we have ever had. But it is impossible to teach so much, and fortunately
it is not necessary. A small part of the public will demand the lesson
in full as I have just given it, even asking for further elaboration, and
we can give it to them, but for the big, big public as a whole, the lesson
must be shorter, very much shorter. Something like the lessons taught
by the big commercial advertisers, such as " He Hears His Master's
Voice," " Eventually, Why Not Now ? " " There's a Reason," and others.
444
APPENDIX
In the practice of radiodontia I have this problem of canal work
brought constantly before me and I have given much thought to the selec-
tion of something sufficiently short to reach the public and yet capable
of accomphshing the purpose I wish it to accompHsh.
I suggest Fig. 480 as an official slogan for the National Dental Asso-
ciation, to be used on bill-boards, street-car cards, advertising spaces in
the magazines, on the handles of tooth-brushes, on tubes containing tooth
pastes, anywhere and everywhere where people will see it.
Fig. 480. Suggested as an official slogan for the National Dental Association.
Aside from the advantage of brevity, this has the further advantage
of arousing the curiosity. When first read it sounds rather nonsensical,
and so gets a second thought from the reader. It allows one who reads
it to become facetious with himself and remark to himself : " Fine advice,
that. I wonder who thinks I have toothache just for spite." And its
greatest advantage is, it can be rewiemhered. Even that part of the public
which demands its dentists to give it the lesson in full will forget most
of the lesson and remember only that there are good reasons why you
should not let your teeth ache.
The situation now is that no person feels any especial pang of regret
and remorse when they " suddenly " — after a few years of neglect —
develop toothache. And why should they? The attitude, if not the
teaching, of the dental profession has been : " Ah, Mr. Citizen, you have
the toothache! Well, that doesn't make any particular difference. I can
fix that in a jiffy for ninety-eight cents."
CANAL SURGERY AND ORAL INFECTION 445
Even though you see the necessity for pubHcity work
flaloca^^rpSS ^^ ^ ^^^ '^' ^"^ ^""^ therefore in favor of it, you may,
nevertheless, think that I am wanting the National
Dental Association to do something it cannot do. Let us see if I am
in the habit of asking for impossible things. What is my attitude toward
dentists who, in my mind, stand convicted of doing bad canal work? I
do not say to them : " You must adopt more modern and expensive
methods of treatment forthwith, and that's all there is to it," for I know
that the great amount of canal work to be done makes this an economic
impossibility. Neither do I ask the National Dental Association to do
something which is economically impossible. What I want it to do, it
can do. It can do the publicity work I suggest, and it must. We owe it
to humanity and ourselves.
The man who thinks this campaign is a financial impossibility has
not given this matter sufficient consideration. We wish to do two things :
We wish to cause the people to ask the meaning of the You-Mustn't-Let-
Your-Teeth-Ache slogan and we wish to have dentists prepared to answer
inquiries regarding it.
The profession of dentistry could not, it is my opinion, raise enough
money to get the You-Mustn't-Let-Your-Teeth-Ache slogan to the people.
But there is a way to get this slogan before the people without spending a
fortune : The manufacturers of dentifrices and tooth-brushes spend mil-
lions of dollars annually for advertising. Most of them would be glad
to use the slogan I have suggested in a corner of all of their advertise-
ments if they were asked to do so by the National Dental Association,
and if they understood the humane object of this campaign. It is a tre-
mendous and pitiful mistake for any one class of men to think they are
any better than another class, and dentists who think manufacturers are
not interested in the welfare of humanity are " dead wrong." Forsythe
and Eastman are manufacturers you know. So much for the problem
of reaching the people.
The problem of preparing dentists to promote the
educating Dentists. education of the public started by a Never-Let-Your
Teeth-Ache campaign can be handled in a most inex-
pensive way. The pages of our dental magazines are always at our dis-
posal and the owners of these magazines have always done their share,
or more than their share, to support such enterprises as the one under
consideration.
I would not have you think that I am obsessed with the delusion that
it will take no money at all to conduct an educational campaign such as
446 APPENDIX
I have outlined, for of course it will. But it will not take " bushels of
it " ; it will not take any more than can be raised with ease ; for there
are thousands of dentists who are more than willing to contribute ; they
want to contribute to such a cause.
It is not impossible, but it is not probable either, that
Ttl the meantime* the publicity campaign outlined in the preceding
pages will be developed. If it is never developed, or
until it is developed, or while it is developing, I advise dentists who desire
to practice good canal work to avail themselves of the help afforded in
Figures 481A to 486. Explain one or two or all of these plates to patients
and you will gain a more intelligent co-operation than you have hitherto
found it possible to get.
Before dental radiographs were used the dentist who wished to
explain canal work and abscess formation to his patients was compelled
to use drawings and models for the purpose. A drawing or a model does
not make the same impression produced by a radiograph, because a
drawing of an abscess is anybody's and everybody's abscess. Somebody
has said something like this : " Everybody's work is nobody's work."
Likewise everybody's abscess is nobody's abscess ; nobody will own it.
But an abscess in a radiograph is some particular individual's abscess ; it
belongs solely and personally to Mrs. Jones, Mrs. Smith or Mr. Hancock,
which makes a world of difference.
Figures 481 A to 486 illustrate how the X-rays may be used to advan-
tage in educational work. A careful study of these plates will prove
illuminative to most dentists and, as an aid to dentists in explaining to
patients the difference between good canal work and no canal work, or
poor canal work, they should prove to be of the utmost value. Indeed
they seem to me to be, at present, the answer for the men who wish to
practice good canal work, but have been unable to gain the co-operation
of their patients.
«i....i,i er^^^x «iK«* There has been much discussion recently as to
material encapsulate whether canal fillmg material should just reach the
^^^' end of the root or pass through it and encapsulate
the end. I leave it a more or less open question as to which is preferable,
believing myself, however, the ideal filling is one which just reaches the
end of the canal, filling all apical foramina, but not passing through into
the periapical space. While it is my opinion that such a canal filling is
the ideal one, it is my further opinion that this ideal cannot, as a rule, be
realized, for, no matter how many radiographs are made at different
CANAL SURGERY AND ORAL INFECTION 447
stages of the work, the fact remains that just at the time the operator is
engaged in the work of filling the canal, he is working in the dark and in
order to get the canal fiUing to the end of the root, he will usually force
a little through. As has been pointed out in the Appendix to Chapter
VI it is sometimes impossible, in upper biscupids and lower molars par-
ticularly, to determine from radiographs whether a canal filling reaches
the apex or not, unless a little passes through appearing as a little button
or cap at the root end.
Canal filling material which passes through the root in a soft condi-
tion and " mushes " out over the root end seems to cause no irritation. A
gutta percha point protruding through the apex, however, is more likely
to produce irritation, pain and suppuration.
It is very unfortunate, but it is very true, that we are much more
likely to have post-operative pain if we fill canals just to or just through
the end of the root than we are when the canal filling fails to reach the
end. It is very discouraging for the conscientious dentist to lose his
patients because he has filled canals well and there has been pain follow-
ing the operation. He knows he might have avoided the production of
the pain by being less thorough. If he has forced a little filling material
through the end of the root, it is not unlikely that he will be condemned
by both the patient and the patient's physician. He very probably has
received a fee which looked large to the patient but which, considering
the time he spent on the case, is less than other dentists are charging who
do not fill canals but whose patients do not suffer after the operation.
Pain after canal filling should be controlled in many cases by the use
of some anodyne, such as an aspirin-codein mixture.
For example
3> Acetylsalicylic acid grs. xxx
Codein sulphate grs. ii.
M. Ft. Caps. No. xii.
Sig. If in pain take one capsule. Repeat in thirty
minutes if necessary. Thereafter every two hours if
in pain.
Filling material through the root end of a lower molar may pass in
the inferior dental canal and encroach on the inferior dental nerve when
the pain is very great and extraction of the tooth may be necessary.
At a dental meeting recently a man asked me, " Is
Ulbat i$ a Bad ^ mechanically imperfect canal filling necessarily a
Canal Tillmg. ^u a^ 1 ^u- ?"
bad canal fillmg?
Look at Figure 487. To the best of our ability to judge, dental
abscesses produce diseases like this, and imperfect canal fillings produce
448
APPENDIX
I'
4\
as tl
\t\
o
loo
©J
o
to aV
a n z «= '
sS CO ^ --I
d 5 O >rH
B Ci,,D O
i-q j:^ h a oo ^-^0)30 3©ox> 0-.
Tj{a«J-0-H«>f>
ii*' a OH I
5 . o J4 .
'iSe
Fig. 482B.
452
APPENDIX
it S5
Ills
ills
ills
si
p.
ill
A
i^B
15- g
T> g in
=;h^ °"^5
T«a$fe,
5 Si-
's a^
. !t
( V 5 •-* rt
£ 5
S'i^:
Fig. 488.
CANAL SURGERY AND ORAL INFECTION 453
B
55 '
r»i
/N
a-s,
•S-g ■3365
■** - O O JC
^■~i«fi».
§v.5.S
:a:i:
; E- a «> '^'
a, o H c d 3
^ ^ Ss o e o :
g.53|^|:
rlfe^Jf H
^BHSL.-..^
s i
5 e ^
' -^mtt^^^k
^^^R
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jmM
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+3 -t* ^,
c ^ ^ a
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) o a o J3
ffl o a (D > E
3 © 3 3
Fig. 484.
454
APPENDIX
S£5
aii
S*""5
S
9 a c a Si A a o t*
Eg ■»> ^->3<-t j=o;dpoc.o-P
U30 10 >>i«-l(I).HCT30Or-l0U
§g P 4
rH "3 *^ «' S * a o '
^»5
m'ond3^Si-io<
3§
ill
« a e
!«'feSS
SSaSs
ti5 -S,
-i; &«+> ©jiHs
Fig. 485.
CANAL SURGERY AND ORAL INFECTION
455
1 .y<
CO
60
O
IE
U
u
s:
•Jl
o
"
iH
s
.3
u
s
VI
U It 1*
a U o
O +> J3
a< 3 f-i
^ S -3 9
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33 CB I
II;
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"^
aM
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ni
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Ul
d
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C
S-S
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r-l
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no o fH
bed
a o o
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Fig. 4S6.
456
APPENDIX
dental abscesses. So mechanically imperfect canal fillings are " bad "
canal fillings, aren't they? Even mechanically perfect canal fillings may,
under certain conditions, be very undesirable things to have in the mouth,
Fig. 487. Case of arthritis deformans. To
the best of our ability to judge, oral
infection causes diseases like this.
(By courtesy of the Dental Digest.)
Fig. 488. Case of arthritis deformans caused
by oral infection.
(Courtesy of Dr. Thomas B. Hartzell.)
for a canal filling may be mechanically perfect without being perfect from
a surgical — i. e., a bacteriological — standpoint and such a canal filling is
certainly " bad."
Any sort of canal filling then, and certainly mechanically imperfect
canal fillings, worry the conscientious dentist and physician when they
are in the mouths of patients who are seriously ill with any disease which
might possibly be produced by some focus of infection.
Through the courtesy of Dr. Thomas B. Hartzell I am able to print
Figure 488. Here is a man with arthritis deformans caused, to the best
of the ability of those in charge of the case to judge, by dental infection.
Think of this for a moment, then answer the question : Shall we continue
to allow people to lay themselves liable to diseases like this, or shall we do
" less and better canal work? "
Case: One of arthritis, neuritis, malnutrition. Man
Hnd^a tSon^ ^^^ "°^ ^^^" ^^^^ *° ^°^^ ^°^ weeks. Referred to
radiodontist by physician. Radiographic examina-
tion revealed dento-alveolar abscesses and much loss of osseous tissue,
CANAL SURGERY AND ORAL INFECTION
457
due to pyorrhea. The affected teeth were extracted. The patient's con-
dition improved promptly and continued to improve for several weeks.
An upper anterior bridge was made, using the two cuspids for abutments.
The Thursday before the Monday when the patient had arranged to go to
work again, he suffered a relapse and developed pain in the region of
one of the abutment cuspids. His physician again sent him to the radio-
dontist. A radiograph was made of the tooth causing pain. It showed
the canal filling reaching only about two-thirds the distance to the apex
Fig. 489. Radiographs of hands of Fig. 4SS.
of the root, and tissue changes indicative of abscess formation in the
periapical region. The bridge was removed, also the imperfect canal
filling. The periapical tissues were disinfected by pumping a four per
cent solution tincture of iodin in water through the root. Again the man's
general physical condition began to improve, and continued to improve
while the canal work in his mouth was done over again, this time checking
the work with radiographs.
From the foregoing it will be seen that the time is already here when
city dentists, at least (when this condition of affairs will prevail in the
smaller town I do not attempt to say) must see to it that they fill canals.
A man may practice septic canal work and not be caught at it, but if he
places a mechanically imperfect canal filling in a tooth any one who looks
at a radiograph of it can see his failure.
458 APPENDIX
In the case just referred to the patient had paid seventy-five dollars
for the bridge. Seventy-five dollars fastened to failures in canal work —
failures zvhich might have been avoided had radiographs been used to
" verify " the canal fillings.
I question the necessity of always making a number of radiographs
of single-rooted teeth to insure insertion of the canal filling to the end
of the root. A radiograph before the tooth is opened, another with a
wire reaching the end of the root and a third when the canal is filled,
certainly cannot be considered bad practice, but I repeat, I question the
necessity of any save the radiograph after the canal has been filled in the
average, non-septic, single-rooted-tooth case.
And now we come to a consideration of the filling
Jli!!2.ir5^?]£ of the canals of molar teeth. Some dentists seem to
molar vcetn. , • , , ... ., , ^,, , , r
thmk that it is impossible to fill the canals of any
molar tooth to the apices of the roots. They are wrong. Other dentists
seem to think that it is possible to fill the canals of all molar teeth to the
apices of the roots. They, too, are wrong.
Figure 490 is a radiograph of the results of an assignment in technic
for the Junior class (1916) at the Indiana Dental College. The assign-
ment was that each student should open the canals of a dissociated
molar through the ends of the roots, then fill the canals by the Callahan
method. The following table (page 459 ") is a record of the results of this
assignment.
A study of the table given will reveal the following pertinent facts :
Number of molar teeth, the canals of which were filled: 61.
Number of teeth used for this work : 225.
Thus the average is that over three teeth were used before the student
succeeded in opening the canals of one.
Total time devoted to the teeth where efforts to open the canals met
with failure: 185 hours 55 minutes.
Entire length of time consumed in the work of opening canals of 61
molar teeth, including the time spent on the failures : 286 hours 30
minutes.
It should be kept in mind that the foregoing time records do not
include the time necessary to fill the canals, and further that, for this
work, no time was consumed to adjust rubber dams and, in other ways,
observe the rules of aseptic surgery.
Three things in particular are responsible for the
OmCa^u'tlriSi? "^^"^ failures: (i) Attempts to speed the work.
(2) Lack of access. (3) Devoting time and thought
to excessive enlargement of the canals near the pulp chamber instead
CANAL SURGERY AND ORAL INFECTION
459
student's
number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
Totals
The tooth
fiUed
Time devoted
to opening
the canals
of the
teeth filled
U. 2nd Mol.
U. 1st Mol.
U. 2nd Mol.
U. 2nd Mol.
U.3rd Mol.
L. 2iid Mol.
U. 2nd Mol,
L. 1st Mol
U. 2nd Mol
L. 1st Mol
L. 1st Mol
U. 1st Mol
Student
U. 1st Mol.
L. 1st Mol.
Student
L. 2nd Mol.
L. 2nd Mol.
U. 2nd Mol
U. 2nd Mol.
U. 1st Mol.
U. 2nd Mol.
U. 2nd Mol
L. 1st Mol.
U. 2nd Mol.
L. 2nd Mol.
U. 1st Mol.
U. 1st Mol.
L. 2nd Mol.
U. 2nd Mol.
L. 1st Mol.
U. 1st Mol.
U. 1st Mol.
U. 1st Mol.
U. 2nd Mol.
L. 2nd Mol.
U. 1st Mol.
U. 2nd Mol.
L. 1st Mol.
L. 1st Mol.
U. 1st Mol.
U. 2nd Mol.
L. 2nd Mol
U. 1st Mol.
L. 2nd Mol.
L. 2nd Mol.
L. 2nd Mol
U. 2nd Mol
U. 1st Mol.
U. 1st Mol.
L. 2nd Mol.
L. 1st Mol.
U. 3rd Mol
U. 1st Mol.
U. 1st Mol.
U. Ist Mol.
U. 1st Mol.
U. 1st Mol.
U. 1st Mol.
L. 1st Mol.
U. 1st Mol.
U. 1st Mol.
L. 2nd Mol.
61
30
20
15
:45
:30
15
:00
30
:45
40
;30
:30
failed to hand
1:00
1:30
faOed to hand
1:35
:45
2:15
2:30
1:50
1:30
3:05
2:30
3:05
:35
:40
3:15
:35
2:30
:15
2:00
:55
4:45
1:30
1:00
3:00
1:00
:55
:45
1:15
1:00
:50
4:30
2:00
2:00
2:00
:30
:30
1:30
1:00
1:15
:30
5:00
2:40
:25
1:15
2:00
1:30
1:30
4:00
2:00
:40
100:35
The number
of teeth
discarded
after efforts
to open the
canals
6
22
1
3
4
2
2
2
1
in work
2
3
in work
5
3
1
2
1
1
5
4
5
1
4
2
3
1
4
3
2
2
1
1
5
3
1
11
2
4
5
1
8
4
3
3
1
3
9
Time
devoted
to teeth
which were
discarded
after efforts
to open the
canals
Total
teeth
used
4:00
5:00
13:00
1:00
2:30
2:00
1:30
2:45
3:15
2:00
1:30
3:00
5:00
3:00
5:15
2:30
1:30
3:00
6:00
7:30
5:00
:45
1:10
6:00
6:00
1:15
5:00
4:00
1:45
1:30
1:00
:50
2:30
2:45
1:30
13:00
1:15
4:00
6:10
3:30
10:00
6:00
3:15
6:00
2:00
5:30
9:00
185:55
3
1
7
23
2
4
5
3
3
3
1
3
4
6
4
2
3
2
2
6
5
6
2
5
1
1
3
4
1
2
5
4
3
3
1
2
2
6
4
1
2
12
3
1
5
6
1
2
1
9
5
1
4
4
1
2
4
10
1
1
Total time
devoted to
efforts to open
the canals in
a molar before
success was
attained
4:30
1:20
7:15
13:45
1:30
3:45
3:00
4:00
3:30
4:55
:.30
4:30
2:30
4:30
6:35
3:45
7:30
5:00
3:20
4:30
9:05
10:00
8:05
1:20
1:50
3:15
:35
8:30
6:15
2:00
2:10
9:45
5:30
2:45
4:30
1:00
1:55
1:35
3:45
3:45
:50
6:00
15:00
3:15
2:00
4:30
6:40
1:30
4:30
1:15
10:30
11:00
2:40
3:40
7:15
2:00
3:30
7:00
13:00
2:00
:40
286:30
460
APPENDIX
of using very small broaches to trace the canals to the ends of the roots.
A friend of mine, a keen observer, declares that " there are not ten
dentists in the world who consistently open molar teeth sufficiently to
make it a physical possibility to open the canals to the end." It is unfor-
Fig. 490. Canal fillings m sixty-one molar teeth. The work was done by Junior dental stu-
dents of the Indiana Dental College, academic year 1915-1916. Though the canals of all of the
teeth were opened through the end, Fig. 490 represents only the first effort to fill them and
many of them are very imperfectly filled.
tunate that the phrase " enlarge canals " is in such common use ; it makes
us think of the operation in the wrong way. The psychic influence
would be better if we should discard the phrase " enlarging canals " for
CANAL SURGERY AND ORAL INFECTION
461
opening canals. The operator, intent on opening canals, has his mind
focused on the place he wishes to reach — the end of the root — while the
man enlarging canals has his mind fixed essentially on just that part of
the canal he is enlarging.
From a study of Figure 490 and chart relating to it, it would seem
that, if given the economic opportunity, dentists should be able to fill the
canals of, say, about one out of three molars, at least. (In the past, I
should say, hardly one out of a thousand has been filled.) For, admitting
Fig. 491. Crooked canal of upper molar filled to the end. (By Dr. Ottolengui, N. Y. C.)
the students' advantage in working on extracted teeth instead of teeth in
the mouth, it is not unfair to presume that dentists are more skillful than
junior dental students. What the very skillful dentist may hope to do
is illustrated in Figure 491, an upper molar filled by Dr. Ottolengui.
Oral Tnfcction*
Reference to the interpretation of radiographs to determine oral in-
fection has already been made in Appendix to Chapter VI, under Mis-
takes Numbers 28 and 29, and just following Mistake Number 41.
The first thing to be said about evidence of infec-
6»idcncc of Tnfectlon tjon which can be seen in radiographs is to emphasize
the fact that one cannot see infection in radiographs;
one sees only evidence of infection. Like all other evidence, it may be
true and conclusive, it may be meager, or it may be false — the diagnos-
tician must judge which.
The pulpless teeth seen in radiographs may be classified as follows :
( I ) Those which show well-filled canals and no bone change in the
periapical region; (2) those which show imperfectly filled canals and no
bone change in the periapical region; (3) those which show well-filled
canals and bone, or root, destruction in the periapical region, and (4)
those which show imperfectly filled canals and bone or root destruction
in the periapical region. (See Chart B B at close of Appendix to
Chap. VI.)
(i) Any pulpless tooth may be a source of infection — even one
with a well-filled canal and no radiographic evidence of bone involvement.
I believe this statement is true, but in practice I assume that a pulpless
tooth with a well-filled canal and no evidence of bone change about it is
not a source of infection, unless the history of the case and the symptoms
are such as to definitely contradict this assumption.
(2) Any pulpless tooth with a faulty canal filling but showing no
evidence of bone change in the apical region is likely a source of some
infection. It is, at least, a potential source of infection.
(3) Any pulpless tooth with a well-filled canal showing bone
destruction at its apex may be considered a source of infection unless it
has but recently been treated and there has not been time for bone recon-
struction to occur. A canal filling which reaches the end of the canal
but does not fill the canal full is, of course, not a good canal filling.
(4) Any tooth showing an imperfect canal filling and bone destruc-
tion at its apex should be considered a focus of infection.
From the foregoing it will be seen that whether the radiograph
shows us something which indicates infection or not is a matter of deduc-
tion. Thus, local symptoms, if there are any, and the patient's physical
conditon should govern our interpretation of radiographs. If the patient
is ill, having a disease which might be caused by a focus of infection, and
462
CANAL SURGERY AND ORAL INFECTION 463
the conditions revealed by the radiograph are such as to indicate probable
infection, and no other infection can be found in other parts of the body,
it is good sense to assume that the radiographic evidence of probable
infection is actually evidence of infection and act accordingly.
Physicians and dentists are prone to disagree regard-
extraction Of tCCtl) to jng the advisability of extracting teeth to overcome
Ocmome Infection , • r .• t-u u ^ u -a ■ a i
oral mfection. ihere is much to be said m defense
of both. Certainly it is not well to indulge in wholesale, needless sense-
less extraction of teeth. But one need have little fear of this, because
of objections which will be raised by the patient.
The reasons for the attitude of the physician are
tl)C Physician's apparent — he wants the patient to recover health
Position. A u .u i ■ u ^ J. -hi
and he therefore wishes to remove every possible
obstacle to such a recovery. He may have found by experience that very
few dentists offer any evidence to prove that they overcome infection
when they treat a tooth — and therefore the only way he can feel certain
that infection will be overcome is to have the teeth extracted.
„„ . .1- - I have had the privilege of observing the manner m
dimination ot , . , t^ ^ 1 • r •,-.,. ^1
TnfCCtion UlitbOUt which Dr. Ottolengui treats cases of infected teeth
extraction. ^nd dental abscesses and it seems to me a physician
has a perfect right to expect some such treatment, and evidence that
infection has been overcome, or insist upon extraction.
Dr. Ottolengui's practice is the logical one. He grows bacteria
from the abscesses he treats, taking the cultures from the canal and from
beyond the end of the root through the canal. He treats the case until
he can no longer recover a culture ; fills the canals and verifies his canal
filling with radiographs. Then — and this is important — makes subse-
quent radiographs to see what periapical bone changes occur.
While I hope I do not underestimate the value of a tooth, I do
believe that in some instances, at least, the physiological value of masti-
cation is overestimated. For example, in the past, the restoration to
health of people who had all their teeth removed and false teeth made
was attributed to the fact that the false teeth enabled them to masticate
their food. H you will recall some of these cases, you will recollect
that the restoration to health began to occur usually before the false
teeth were made and so was very probably due to the elimination of oral
infection.
464 APPENDIX
Continuance Of While my experience leads me to believe that it
Infection Hfter seldom occurs, I must grant the possibility of a con-
cXtraction* tinuance of infection after removal of an abscessed
tooth. There is, therefore, some advantage, and I can see no disad-
vantage, in practicing currettement after extraction of abscessed teeth.
When an abscess cavity persists after extraction of a tooth, it is some-
times due to the fact that the approximating tooth is abscessed — Figure
189.
The subject of oral infection due to pyorrhea
Pyoithea. admits of little discussion. I must say, however,
that many cases of pyorrhea are treated where,
owing to the amount of bone lost, a cure is impossible. (Figure 204.)
It is remarkable, however, what beneficial general effects are produced
sometimes by treatment of incurable pyorrhea cases. Perhaps the de-
sirable, beneficial, general effects on cases of arthritis and other systemic
diseases is due to the fact that the surgical treatment for the pyorrhea is
equivalent to an administration of a bacterine (usually called a vaccine).
Pursuant to this idea of a surgical procedure being
^e to Se*f xtracted equivalent to an injection of a bacterine. Dr. Hartzell
has suggested that, in cases for extraction of many
infected teeth — i.e. abscessed teeth and teeth affected with pyorrhea —
only one or two or a few teeth at a time be removed, at intervals. There
will sometimes be an exacerbation of symptoms — i.e., a " reaction "■ —
following surgical treatment, quite similar to the " reaction " following
injection of a bacterine.
There is a fundamental difference in the treatment
PcrE^taTlnf^tiott *~*^ dental abscesses today as compared to the way
in which they have been treated in the past. Dental
abscesses should no longer be treated as a local disease. To state it dif-
ferently, dentists must cease to treat abscesses and commence to treat
the patient. In this work of treating the patient the dentist should be
willing and anxious to co-operate with the patient's physician. Ever
since I can remember, dentists have been crying for physicians to recog-
nize the importance of the mouth. Physicians do recognize the hygienic
importance of the mouth now and — is it not true? — dentists are crying
because they do.
Naming the methods in order of their effectiveness and reliability,
periapical infection may be treated in seven ways: (i) By extraction
and currettement. (2) By extraction. (3) By root resection and cur-
rettement. (4) By currettement. (5) By Ionization. (6) By forcing
CANAL SURGERY AND ORAL INFECTION 465
some drug, such as phenolsulphonic acid, 50 per cent., or tincture of
iodine, 3 or 4 per cent, in water, through the canal. (7) By seahng
volatile drugs in the pulp canal.
The amount of bone destruction governs to a great degree the method
to be employed — the more bone destruction there is the more effective
the method of disinfection must be. (See Charts C C and D D at the
close of Appendix To Chap. VI.) But the amount of bone destruction
is only one of the things which governs the treatment indicated. The
ability of the operator, the health of the patient, the condition of the other
teeth in the mouth, the patient's financial and social standing, the time
which can be devoted to the work and other things must also be
considered.
Perhaps I will help my reader most by showing radiographs of cases
which have been treated, and then let him judge for himself what par-
ticular method he will follow in any given case. Before doing so, let me
say that, unless a tooth is extracted, the use of post-operative radiographs
is an absolute necessity.
Later developments in our rapidly growing knowl-
RCflCncration Prow ^^^^ regarding oral abscesses may prove me wrong
eradication Of in this, but just now (January, 19 17), I assume that
infection has been overcome if I get a complete
bone regeneration in the abscess cavity in about a year. (While, as I say,
I assume that infection has been overcome in the event mentioned above.
I, nevertheless, recognize the lack of definite knowledge on this subject
and I would not object strenuously to the removal of such a tooth if it
gives any hope whatever of benefiting or curing a very sick patient, and
it was the patient's and the patient's physician's desire that the tooth be
removed. I might consider the removal of the tooth the " drowning
man's grab at a straw " but I would not refuse the one about to drown
that last privilege.)
CASES
Abscess upper lateral and central. Particularly
X^^f^ bad case on account of bone destruction alonsf sides
il anaB. . ... ,, . ,. , *' .
of roots, which usually mdicates an abscess cavity
very deep facio-lingually.
Prognosis at time treatment was started : very doubtful.
Treatment : Phenolsulphonic acid, 50 per cent., through apex, out
fistula, three times, at intervals of about five days. Dressing in canals
during intervals : formo-cresol at times, cresol or creosote at other times.
Canal filling: Callahan method.
466
APPENDIX
Result : Secession local symptoms. Fistula closed. No general
symptoms. Radiograph, Fig. 492A, made in April. Radiograph, Fig.
492B, made in September, five months later. Fig. 492B shows con-
Fig.
492A. Abscess upper lateral and cen-
tral; before treatment.
Fig. 492B. Same case as Fig. 492A, five
months after treatment. _ Note considerable
bone reconstruction. Disinfected with phe-
nol-sulphonic acid.
Fig. 493A.
Abscess upper lateral incisor; be-
fore treatment.
Fig. 493B. Same case as Fig. 493A, five
months after treatment. Disinfected with
a 4 per cent, solution of tincture of iodin
in water. More canal-filling material
through end than desirable, but apparently
causing no irritation.
siderable bone reconstruction. (Operator, Dr. Karl Kayser of Indian-
apolis.)
Abscess upper lateral incisor.
w'anO Prognosis at time treatment was started ; good.
Treatment : Four per cent, tincture of iodine in
water through apex, three times, at intervals of five days. Dressing in
canals during intervals : f ormo-cresol, cresol or creosote. Canal-filling :
Callahan method.
CANAL SURGERY AND ORAL INFECTION 467
Result: Radiograph, Fig. 493A, made in April. Radiograph, Fig.
493B, made in October, six months later. Fig. 493B shows bone recon-
struction in spite of the amount of gutta percha through end. Ex-
rig. 494 A. Abscess lower bicuspid; before Fig. 494B. Same case as Fig. 494A, seven-
treatment, teen months after treatment.
Fig. 495A. Abscess upper lateral incisor; Fig. 495B. Same case as Fig. 495A, ten
before treatment. months after treatment. Disinfected by
ionization.
cept following the first injection of iodine there were never any local
symptoms. General symptoms : autointoxication, which disappeared after
treatment of tooth. Patient gained twenty pounds in three months.
(Operator, Dr. Carl Emmert, of Indianapolis.)
Abscess lower second bicuspid.
HflHd^R Prognosis at time treatment was started (judging
from appearance of radiograph) : fair.
Treatment : Treated from April first to April eighteenth, then filled
by Callahan method. Sodium and potassium compound used to sterilize
canals. Dressings sealed in canals not known.
Result : Local symptoms subsided, fistula closed. Figure 494A was
made April i, 19 15. Radiograph, Fig.,494B, was made in August, 191 6,
468
APPENDIX
Tig. 495
B ana B.
seventeen months later. Figure 494B shows complete bone reconstruc-
tion built in about the root and filling material through the end of the root.
(Operator, Dr. A. W. Bark, of New York City. I am indebted to Dr.
A. Berger, of New York City, for bringing this case to my attention.)
Abscess upper lateral incisor.
Prognosis at time treatment was started (judging
from appearance of radiograph) : fair or good.
Treatment : Ionization, 3 per cent, zinc chlorid solution on cotton in
pulp chamber, zinc electrode fastened to positive pole against saturated
cotton, negative pole, sponge on cheek, one-half milliampere for five
minutes. (Patient did not feel current.) Three treatments: first treat-
ment, February eighteenth ; second treatment, March eighth, eighteen
days later ; third treatment, March sixteenth, eight days later. Canals
filled March sixteenth.
Fig. 496A.
Abscess upper lateral incisor;
before treatment
Fig. 496B. Same case as Fig. 496A, six
months after treatment.
Result : Figure 495A was made in February. Figure 495B was made
in December, ten months later. Figure 495 B shows the abscess cavity
entirely filled with new bone. There is considerable canal filling through
the end — it is gutta percha. The fistula closed after treatment. (Oper-
ator, Dr. Marcus Straussberg, Newark, N. J. Items of Interest, April,
1916.)
Abscess upper lateral incisor, canal not filled.
Prognosis at time it was decided to resect root : con-
sidering the nature of the treatment decided upon,
excellent.
Treatment: Root resection and curettement, end of canal filled with
amalgam. (Filling the end of an unfilled canal with amalgam is especially
Tig. 496
H and B.
CANAL SURGERY AND ORAL INFECTION 469
advantageous when the tooth has a post crown on it. To the writer, this
procedure seems, in most cases, very good practice. If the canal is filled
just previous to the root excision it is hardly necessary, for the operator
is then sure the canal is filled full. But even when the radiograph shows
us a canal filling reaching to the end of the root or to the point where
the root is to be cut off, we cannot be sure the canal is filled solid full —
hence, the advisability of sealing the end with amalgam. As far as I
know, this procedure is original with Dr. C. D. Lucas, of Indianapolis.)
Result : Figure 496A was made in April. Figure 496B was made in
October, six months later. Figure 496B shows regeneration of bone.
Patient recovered from keratitis within three weeks after operation.
There is a belief among many dentists that the root end is excised be-
cause it is rough and therefore a mechanical irritant. A roughened root
end is a necrotic, infected root end and, for this reason, it is excised.
I must make the statement, as we consider the matter of bone recon-
struction, that I have seen it occur following disinfection of the canals
of the tooth and the pus sinus when the canals zvere not fiWed to the end.
Some Essentials Kegarding the Cccbnic of Tottization.
Ionization is a process of introducing drugs into tissue by means of a
unidirectional electric current. I take pleasure in recommending the book,
" Dental Electro-Therapeutics," by Dr. Ernest Sturidge ; publishers, Lea
& Febiger, as an authoritative work on this subject. Prinz's " Dental
Materia Medica and Therapeutics (Mosby, St. Louis), also carries a fine
chapter on this subject.
The process of ionization seems to the writer to hold great possi-
bilities. The principle of its application is illustrated in Figure 497.
When some drugs are used ; iodine, for example, the polarity must be
changed from that indicated in Figure 497.
' Figure 498 is an ionization machine. We see the following parts :
(i) The main switch, (2) the pole changing control, (3) the rheostat.
(4) the milliammeter, (5) the pilot light.
The following are elementary points regarding ionization calculated
to help the beginner :
Turning on the current: When connections are all made, advance
rheostat slowly. Stop when there is sensation ; wait, then advance slowly
again. Do not cause pain.
Strength of current: Use anywhere from one-half to five milli-
amperes.
470
APPENDIX
Time of ionization treatment : About five to ten minutes.
Number of treatments and time of intervals: About three treatments
at intervals of about five days.
Turning off the current: Turn the rheostat slowly (not as slowly as
it was advanced, however) to avoid pain. Turn current off before re-
moving electrode.
AN IONIZATION REFERENCE CHART.
Drug.
Put the
Drug on
Wrist or Indif-
ferent Electrode
{Moisten with
water).
Iodine.
(Aqueous solution or equal parts tincture and
water or Lugol's Solution.)
Negative Pole.
Positive.
Zinc Chloride.
3% solution in water or
a pure zinc electrode with a solution of Sodium
Chloride in the canal.
Positive Pole.
Negative Pole.
*Copper Sulphate.
2% solution in water.
Positive.
Negative.
Cocaine Hydrochloride.
Any desired strength solution in water.
Positive.
Negative.
H2O2
full strength as supplied by pharmacist.
Negative.
Positive.
*Emetine Hydrochloride.
4% in water.
Positive.
Negative.
*Silver Nitrate.
3% in water.
Argyrol 20%.
Positive.
Negative.
^
I
( - ■ .
1 J
0M>
Fig. 497. Illustrating the
principle of ionization.
Fig. 498. An ionization
machine — wall type.
CANAL SURGERY AND ORAL INFECTION 471
Some Points Redaraind Sterilization and tbc Practice of
Jlseptic Pulp €anal OPork.
The hands: Scrub with soap and water, then handle nothing but
sterilized instruments and accessories. After scrubbing-, if it is desired to
have the hands more surgically clean, dip in bichloride of mercury solu-
tion, I :iooo, then distilled water, then 70 percent, ethyl alcohol.
Instruments: Boiling water for twenty minutes. Two percent, bi-
carbonate of soda, also two per cent, phenol may be added to water if
desired.
Accessories other than instruments should be sterilized in a steam
sterilizer, which admits of turning the steam into or out of the sterilizing
chamber. The technic for the use of such a sterilizer consists first, of
course, in placing the articles to be sterilized in the sterilizing chamber :
Heat for about twenty minutes before the steam is turned into the steril-
izing chamber. Turn steam into chamber for thirty minutes. Turn
steam out of sterilizing chamber, leaving heat on for about twenty min-
utes. This dries the sterilized articles. (The Wilmot Castle Company,
Rochester, N. Y., makes steam sterilizer of the type the writer has in
mind.)
Napkins and linens of all sorts, paper canal points, cotton, cotton
sponges of all si::es: Wrap in gauze or unbleached muslin, pin shut,
sterilize in steam. Do not open packages until ready to use.
Rubber Dam: Cut, lay between layers of muslin, sterilize in steam.
Paint after its adjustment with 70 per cent, alcohol, painting the teeth in-
cluded in the dam adjustment. Tincture of iodin may be used also if
desired.
Cotton Swabs on Broaches: By using a broach holder for the dental
engine, a great number of smooth broaches may be nicely wrapped with
the desired amount of cotton, then sterilized with steam. Wrap in muslin,
sterilize, then open wrapping only when ready to use.
Gutta-Percha Points: May be sterilized in steam. Do not allow the
points to touch one another when subjected to the heat or they will stick
together. Keep in 70 per cent, alcohol.
After sterilization, it is expedient to keep all pulp canal paraphernalia
in a formaldehyde " sterilizer " ( ?) or case where nothing else is kept.
472
APPENDIX
In further consideration of the matter of asepsis and
Dr, Best's CbiirtS. infection, a perusal of Dr. Best's Charts VI and VII
will prove to be instructive.
Provable Causes or Pemapicai. Abscesses
-' CoTOf CR FhflOusarXNTS
r""_ IN ^jLD lA-iAlS
I. rp'jfi CaPosed
J r- BROrtChCS W'lTi
L - ' -X BEF CE ^\AriKO
PJL" l5^
Chart VI. " In case we have been guilty of any of these conditions, we have contributed our
share to the great number of infected pulpless teeth. Arsenic is dangerous and unnecessary.
Periapical tissues are frequently destroyed by powerful drugs sealed in canals, and these areas
may become the seat of infection of secondary origin, hemotogenous origin." Dr. Elmer S. Best.
Chart yil. " Contains some practical hints which will assist us in having more satisfactory re-
sults with our operation. In dental surgery, where we come in contact with the patient's system,
. the same principles apply as in surgery." Dr. Elmer S. Best.
Some essentials Regaraiiid CecDnic of Tnoculatittd Culture
media from tbe Canals of Ceetb
Recommend little book, " Laboratory Methods," by Williams &
Williams (Mosby, St. Louis).
Culture media can be purchased from Parke, Davis & Company, and
other reliable manufacturers of biologic preparations. Suggested media :
Ascites dextrose agar and dextrose bullion.
Technic: (i) Flame platinum inoculating needle. (2) Insert
platinum needle in canal of tooth. (3) Remove needle from tooth. (4)
Flame cotton in mouth of culture tube. (5) Remove cotton. (6) Flame
mouth of culture tube. (7) Make plant in culture with needle. Avoid
touching sides of culture tube with needle. (8) Flame mouth of culture
CANAL SURGERY AND ORAL INFECTION 473
tube. (9) Flame cotton. (10) Reinsert cotton in tube. (11) Flame
cotton. (12) Within an hour, place tube in incubator.
An electric incubator 9 x 9 x 12 inches (inside dimensions), suitable
for dental use, can be obtained from The Chicago Surgical and Elec-
trical Company, Chicago, Illinois.
The incubator temperature should be about 37^° C. A growth will
usually occur, if at all, in from forty-eight to seventy-two hours.
The matter of examining cultures and determining the nature of the
organism, obviously, cannot be considered here. If possible, this work
should be turned over to an expert laboratory man.
Fig. 499A. Three apical foramina in lower bicuspid filled by the Callahan method.
Cbe Cccbnic of Openiitd ana TilHttd Pulp £mnH
Certainly it is not out of place to include in this chapter something
regarding pulp canal technic.
No man in the world is better fitted to describe this technic than
Dr. John Callahan, of Cincinnati, who has generously granted me per-
mission to print the following two papers by him : one, " Root Canal
Preparation " ; the other, " Root Canal Filling."
Figure 499A is a radiograph of a lower bicuspid. It shows the main
canal branching, at the apex, into three. All three of these small canals
and apical foramina are filled. As far as I know, this can be done only
by the Callahan method.
474
APPENDIX
Root €andl Preparation.
By J. R. Callahan, D.D.S., Cincinnati, Ohio
It is certain that much may be judiciously argued in favor of the
drill, or of chemical and mechanical treatment for root preparation, and
there is something to be said against each agent or combination of agents,
and that is what, on the present occasion, I have to say.
To state one argument is not necessarily to be deaf to all others, and
that a man has written a book of travels in Russia is no reason why
he should never have been in Africa.
Whether it be a tooth from which a devitalized pulp is to be re-
moved after arsenical application or pressure anaesthesia, or the opening
and cleansing of a pulp canal that shows a moist or dry gangrenous
tissue, or any or more of the numerous pathological pulp condition or
conditions beyond the root end, the goal, the strategic point, is the apical
foramen or foramina : foramina in ninety per cent, of adult teeth.
It is then the duty of the operator to obtain a sterile and as direct
and as free a passage to the strategic point as the nature of the root
canal will permit. It does not meet the present day requirements to say,
as do some of our text books and essayists, " open the root canals to the
end." Our inquiry is, how is this seemingly simple little thing to be
done ?
To undertake the opening and preparation of a root canal should
indicate that the dentist recognizes the necessity for removing every
atom of devitalized tissue, having the canal throughout its entire length
and in all of its ramifications, including the dentinal tubuli sterile and
in such shape and condition that the canals, the tubuli, the foramina may
be permanently sealed or filled.
Diagnosis, filling of canals or treatment of conditions around and
about the root, are not to be discussed further than may be necessary to
make clear the reasons for certain steps to be mentioned.
The dentist should on every possible occasion avail himself of the
advantage to be obtained through having one or several radiographs be-
fore him for comparison or study. We cannot be reasonably sure of the
effectiveness of our efiforts without such assistance, nor can we be ab-
solutely certain with them. Many of the pictures thrown on the screens
and printed in our journals as evidence of perfect technic and results are
about as clear as rabbit tracks in the snow on a windy day, when it is
a difiicult matter to determine whether brother rabbit is going or coming,
the strategic point being conspicuously absent. Improved apparatus and
technic will some day overcome these shortcomings. Inasmuch as the
largest number of dentists are for one reason or another deprived of the
CANAL SURGERY AND ORAL INFECTION 475
valuable assistance of the X-ray, and our literature is being surcharged
with most accurate information in this line, let us then on the present
occasion keep in mind the great majority who get along the best way
possible without this expensive adjunct.
All operations upon the root canal from begin-
HseVtiC 0»cratiOtt ^^"^ ^° completion are purely surgical and should be
KCCOmtnendC^. conducted upon surgical principals; this being true,
the maintenance of aseptic conditions is of first
importance.
Radiated heat and superheated steam in combination is the only ac-
ceptable method for the steriHzation of instruments, cotton, paper points,
gutta-percha points, etc.
Steam chests that are best adapted to this use are known as the
Pentz System, made by the Santiseptic Manufacturing Co., Tompkins-
ville, N. Y., and a double chambered steam chest made by the Wilmot
Castle Co., of Rochester, N. Y.
The opening of the pulp chamber should be ac-
OveninaintO complished with as little disturbance of the devital-
Pulp Cbaittber. ized pulp tissue as may be possible : to this end it
will be well to cut through the dentin with a drill,
then use carborundum disks and stones, keeping the carborundum stones
moistened with water that contains a liberal supply of carborundum
powder. This enables the stone to cut rapidly without heating the tooth.
Better results will be obtained if, while using the stones and car-
borundum powder, all of the tooth crown be removed that interferes
with pulp chamber enlargements that may be necessary in getting direct
access to the end of the root.
Sufficient enamel and dentin having been removed to give a clear
view of the pulp chamber, it will be well to prepare for the placing of
the rubber dam, by means of threads, fine polishing strips, separators or
by whatever means necessary to insure the dam going to place with little
or no forcing. There should be no leakage whatever about any of the
teeth included in the field of operation.
If the cavity margin reaches to or below the
_, gum line then a copper band should be fitted and
Tacllitak Use cemented to place about that tooth, so that the dam
Of Ktlbbcr Dam. ^nd clamp can be placed upon or over the band and
tooth without danger of displacing the band.*
*It will sometimes be practical to put the rubber dam clamp on the tooth
posterior to the one with the band on it and bring the dam forward to mclude the
banded tooth.— H. R. R.
476 APPENDIX
The dam being in place, bathe the exposed
RcmoVfll Of teeth, rubber dam and clamp, etc., with a seventy
Pulp per cent, alcohol solution or tinct. iodine. This
strength of alcohol is a more .effective germicide
than the ninety-five per cent, generally used. With warm air dry the
cavity : with small fissure drill make a circular cut, leaving a cap of den-
tin over the pulp chamber which may be removed by a blast of air or a
fine excavator. Having exposed the pulp it will in many cases be well
to toughen or harden the pulp tissue by placing a drop of alcohol and
formalin (about five per .cent, formalin) on the devitalized pulp for a
few minutes. Then with hot air dry the pulp, when a fine broach is
passed alongside the pulp or largest branch of the pulp. Slightly turn-
ing or rotating the broach and withdrawing the broach, will in many
cases bring the entire pulp, including the smaller branches of molar pulps.
Every possible effort should be made to get the entire pulp at the
first trial. The extracted pulp should be spread on white paper and
examined with a magnifying glass that the operator may know the loca-
tion of pulp fragments if there be any.
The three methods of procedure, from this
■ ' Gkansiltd point, that we wish to discuss briefly are : the drill,
(Canals* the sodium-potassium, and the sulfuric acid and soda
bicarbonate.
The open chamber and canals should. first be washed out with nor-
mal saline solution ; dry, then place shred of. cotton saturated with
clove-oil well within the large or open canal to remain while we go in
search of the very minute canals that may be so small that it is a difficult
matter to find them.
Paint the floor of the pulp chamber with tincture
jljj ^1 of iodine. When the surplus iodine is absorbed by
Canal Drills. a cotton pellet, little dark spots will, in most cases,
reveal the location of the canals. The finest Kerr
drill, manipulated by hand, without pressure, will enter a very fine canal
by gently rotating the drill, and being very delicate and flexible and
threaded like a screw, will in most cases bring away the remaining pulp
tissue, when the canal may be enlarged by gradually increasing the size
of drills, or the drills may be worked in and out of the canals as files.
. . These flexible drills will go around a slight curve if the canal is
large enough to give the instrument free play. If the instrument binds,
at or near the curvature, a false pocket will be made on the outer wall
of the canal at the curve. The little pocket or pit in the dentin, at the
point indicated, prevents further instrumentation within that canal.
CANAL SURGERY AND ORAL INFECTION 477
Each and every root canal is more or less of a law unto itself. A
correct radiograph is of inestimable value. In the absence of the X-ray
picture, the operator will be greatly assisted by making a pencil sketch
of the probable shape of the tooth. In this way his memory will be
refreshed and he will be made more keen and alert as to the probable
difficulties ahead.
In some cases it may be of advantage to sink a shaft in the root
using a bud drill, following the fine canal from a third to a half the
length of the root, following the canal from this point with the fine
flexible drill.
By being patient and careful many of the finer canals may be opened
to the foramen.
It is possible, however, that septic matter or pulp fragments that
may become septic, have been forced through the foramen into the
apical space.
It is not possible that the multiple foramina, or the collateral canals,
or the connecting canals or the flat thin cancellous spaces between the
main canals in double roots have in any sense been opened or cleansed
The drills in many such roots have simply drilled holes through
organic substance in various stages of disintegration. Such substances
cannot be washed or swabbed out but are left within the canal, some-
times saturated with such antispetic medicaments as may be applied, and
finalty incorporated with the root canal filling.
Schrier's kalium-natrium, or sodium-potassium,
^.^-..^ n<.^««..:..^ as we more frequently name it, is a concentrated
$oaium-rot(i$$iutii ,, ,. , . , . ,
m^tbOd of alkali caustic ; explosive when in contact with water,
CrlCanSing CaitalS* yet a most useful agent when carefully and skillfully
handled, for the purpose of removing organic
substance from root canals. It is also a useful adjunct for opening and
enlarging root canals after the manner advocated by Drs. Rhein and
Ottolengui.
If the dentist will moisten a spot of skin on the back of his own hand
and place thereon a small particle of sodium-potassium he will realize at
once the necessity of giving close attention to the protection of the patient,
including the nostrils, which should be protected in some way.
All the pulp tissue that is within reach of the broaches having been
removed, small particles of the sodium-potassium, size of a pin head
if placed where the very fine canals should be, the dentin being moist will,
by dissolving the organic substance, reveal the elusive anterior canals of
lower molars or buccal canals of upper molars. These canals after being
478 APPENDIX
located and having been exposed to the action of the sodium-potassium
for a fevv? minutes, should be attacked with what has been named " picks,"
Dr. Rhein having devised a very sufticient instrument under this name.
An instrument will be illustrated later that has the advantage of being
more rigid and also having interchangeable points.
These picks, with assistance of the sodium-potassium, which breaks
down the organic matrix of the dentin, converting it into a soapy-like
mass, which acts as a lubricant, will work their way into the canal, enlarg-
ing and sterilizing in a most satisfactory manner.
After advancing a distance into the canal, if the pick begins to bind
or lock, thereby becoming a piston within the canal, a large Gates-
Glidden drill, from which the point has been ground, may be used to
enlarge the lumen of the canal so that the pick may work more freely.
When having reached the region of a curve in the canal or a near
approach to the foramen, it will be safer to use a finer instrument, a
Donaldson broach, from which the barbs have been partially removed, for
the purpose of negotiating the curve if possible ; also to eliminate as much
as possible the piston effect of the larger instrument that might force the
caustic contents of the canal into .the region beyond the foramen, and do
damage that will be difficult to control.
I have had two severe burns in my practice from this cause. In one
case the tooth had to be extracted, and the second one I fear will be
lost.
Chemical substances which cause death and degenera-
* tion of tissues are called caustics.
Alkalies, such as sodium-potassium and calcium.
Acids, such as hydrochloric, sulfuric, nitric, arsenius and carbolic,
and the salts of some metals, such as silver nitrate, zinc chloride, copper
sulphate, are the most common types of caustics.
The alkalies and metallic salts act by uniting with the albumins, act-
ing as albumin solvents.
" The caustic alkalies are not self-limiting : they penetrate deeply
into the tissues and destroy the albumin of the mucous surfaces, the horny
tissues and the external skin."
Necrosis, followed by eschar formation, is caused by strong caustics,
the necrosis involving tissues at various depths, depending upon the
strength of the caustic, the nature or mode of its action, and the time it is
allowed to act.
" Those agents are best suited by cauterization which, like concen-
trated sulfuric and fuming nitric acid and silver nitrate, penetrate to
CANAL SURGERY AND ORAL INFECTION 479
the deeper layers of the skin and mucous membrane only after acting
for some time."
The treatment of chemical injuries, of recent cases, should be directed
toward neutralization of the agent before it penetrates deeply.
Chemists and apothecaries usually have two solutions ready. Acetic
acid or vinegar is used to neutralize the alkalies, while a solution of
sodium bicarbonate is used to neutralize the acids.
If, for any reason, it is suspected that sodium-potassium has passed
beyond the foramen, a sulfuric acid solution should be applied quickly
followed by soda bicarbonate solution.
I have no doubt that through some of the large foramina, at least,
the caustic has wrought harm.
In the constricted canals and in the constricted apical region the
use of sodium-potassium is frequently indicated. The dangerous qualities
of a valuable agent should not cause us to overlook its useful qualities.
Twenty years ago sulfuric acid solution and
^.M^.uiM-a^ia soda bicarbonate solution came into use.*
SUITUriC HCItt ^, ,-..,, , . ,
method of J- he sultunc acid is used for the purpose of
0lC(in$ind ^aittllS* softening the surface of the pulp canal walls to per-
mit the passage of the barbed or roughened broaches
to and fro through the canal, enlarging the canal by breaking loose the
softened dentin. Soda bicarbonate solution is thereupon injected into
the canal that the broken down dentin and other disorganized substances
may be removed from the canal by effervescence caused by the escape
of carbonic acid gas that is the product of the neutralizing action of the
soda bicarb, upon the sulfuric acid.
This reaction leaves the canal in a state of surgical cleanliness. This
cannot, to my knowledge, be said of any other method or agent.
Twenty years is a long time for a method or theory to stand prac-
tically unaltered. Notwithstanding the age of the so-called sulfuric acid
treatment (which might much better have been entitled, " Sulfuric acid
and soda bicarb, treatment"), a brief resume of the theory and practice
of the doctrine may not be amiss.
Concentrated sulfuric acid is also an active escharotic. The acid
caustics act by burning the structure with which they come in contact.
They not only disintegrate albumen but attack many other organic
substances. The breaking up of inorganic and the carbonization of
organic substances is to be borne in mind.
Limited and mild caustics when applied cause an inflammatory
action, depending upon the strength and time of application.
* Given to the profession by Dr. Callahan. — Ed.
48o APPENDIX
A fifty per cent, (by volume) solution of sulfuric acid will soften
cotton on the carrying instrument. A weak acid solution gives a cor-
respondingly weak reaction in the presence of the soda solution.
The strength of the acid solution should be not less than twenty
per cent, and not above forty per cent, for root canal work. In my own
practice thirty per cent, to forty per cent, aqueous solution or commer-
cial sulfuric acid by volume is the standard.
Soda bicarbonate should be a saturated solution.
In relation to the action of the acid solution on bone tissue, Mr.
George Pollack, F. R. C. S., Surgeon to St. George's Hospital, says:
" Dilute sulfuric acid does not affect the living, acting chemically on dis-
eased bone alone." He gives the following experiments : " Portions of
dead, diseased and healthy bone were selected and subjected to the action
of sulfuric acid,"
viz. : No. I. Dead bone lo grains
2. Diseased bone lO grains
3. Healthy bone (middle age) . . 10 grains
4. Healthy bone (old age) 10 grains
" Exposed to the action of a mixture of sulfuric acid and water one
part in four, for three days, at a temperature of one hundred deg., the
following were the results :
No. I. Dead bone, phosphate of lime 2 grs. Carbonate of
lime 3.3 grs. dissolved in the mixture.
No. 2. Diseased bone, phosphate of lime 2 grs. Carbonate of
lime 1.3 grs. dissolved in the mixture.
Nos. 3 and 4. In both specimens of healthy bone no action
took place."
Dr. Garretson, in the treatment of caries of the maxilla, recommends
the use of the officinal ordinary sulfuric acid.
On the diseased or partially disorganized soft tissues the solution
will have a corrosive and astringent effect, or in other words, will break
down or destroy the diseased tissue, leaving a fresh, clear field for nature,
with the assistance of mild antispetic treatment, to take care of herself.
Why does not sulfuric acid attack and destroy divitalized dentin?
The acid at first attacks the tooth substance, breaking down the lime-
salts, at the same time corroding or carbonizing the organic substance,
forming a new compound, thereby establishing a barrier to the further
progress of the acid.
Prof. Cassidy, see Dental Chemistry and Materia Medica, says : " The
acid attacks the earthy portion forming insoluble calcium sulphate (Ca
S04), at the same time dehydrating the animal or gelatinous portion,
which is mainly made up of carbon, hydrogen and oxygen. These two
CANAL SURGERY AND ORAL INFECTION 481
latter elements are withdrawn as already alluded to, leaving the inde-
structible carbon as a residue to be incorporated with the insoluble sul-
phate, producing thus, a protecting covering to the unaffected parts
beneath, against further inroads of the causing agents."
This protecting covering of carbon and calcium carbonate are re-
moved or scraped away by each excursion of the rough broach, permitting
the acid to take another bite at the dentin.
The same chemical and mechanical action is repeated so long as the
broach is kept in motion in the presence of the acid solution.
The depth to which the acid affects the dentin is, unfortunately,
immeasurably small.
It would be a great advantage to the work in hand if the acid would
or could be made to penetrate further into the dentin. The reason why
a larger area of the dentin is not at once affected has already been men-
tioned. It may be well to recall, however, that dentin consists of an
organic matrix, a reticular tissue of fine fibrils richly impregnated with
salts of calcium. Traversing the matrix are long, fine canals or tubes,
the dentinal tubules, twenty-five to thirty thousand to the square milli-
meter. Immediately surrounding the tubules the matrix is especially
dense, forming a lining or sheath to the tubes, known as the dentinal
sheaths or Neuman's sheaths. Neuman's sheaths are insoluble in boiling
sulfuric acid.
Sulfuric acid causes delicate steel instruments
IHi^thAd flf ^° become brittle and to break on small provocation,
Jlpplying HCid leaving small pieces of steel buried within the canal.
in 0(in(ll$* This unpleasant accident is, as a rule, due to the
manner of manipulating the broach.
For very fine canals the barbs should be partially or wholly removed
from the broach or a fine broach can be made from gauge twenty to
twenty-five piano wire. These broaches should be cut to proper lengths
and placed in a rigid holder or handle that will hold the broach in a
direct line with the line of force. Either pressure or traction may be
applied to the delicate steel point. For the heavier work, digging or
enlarging should be done with larger and stronger points, made of rough-
ened steel A better and safer instrument may be made by taking the
largest tantalum silicate plugger points, No. 104 or 105 S. S. W, ,bend to
straight line, remove from the handle, file or grind to proper shape, and
place in the strong right-angle broach holder made of ivory. This makes
a most effective root and canal excavator.
The metal is not acted upon or altered in any way by acids. This
manner of enlarging or excavating the canal to a large extent at least
482 APPENDIX
eliminates the probability of making a false tract or pocket within the
canal, and does away with the necessity of using a drill, at least, until
the canal is large enough to make drilling a safe procedure.
The point that I am trying to develop is that I believe that the best
results are to be obtained by eliminating the undesirable or dangerous,
and taking advantage of the safer and desirable features and results, that
may be obtained through the use or application of every chemical agent
or instrument that will meet the exigencies of the case in hand.
In straight and sufficiently open canals or in canals that have been
enlarged by chemical means to a sufficient size to pilot the root drill, for
the sake of speed, for convenience in shaping of canal, a Kerr drill, or a
Gates-Glidden, from which the point has been ground, or bud drill, may
be used.
If the finer canals contain fairly well organized pulp tissue that the
broach fails to engage, sodium-potassium should be applied. After the
pulp or other organic tissue has been converted into a soapy substance,
the removal of this soap from the canal becomes a necessity ; some of
it may be removed with a stream of water; only a small proportion, how-
ever. Swabbing with cotton on a broach does but little better. If the
root canals of an extracted tooth be opened and thoroughly treated with
sodium-potassium, the canals then washed out with water as would be
done if the tooth were in the mouth, and if you then dry the tooth and
crack open the roots, in the apical third or the root canal a dark, rather
dense, soapy mass will be found packed within the fine canal. If the
tooth fragments be kept dry for a day or so the dentin will show a green-
ish yellow color — not a very pronounced discoloration, but sufficient to
show the presence of a coloring matter. All of this soapy mass will be
thoroughly removed from the canal, if sulfuric acid be pumped into the
canal in sufficient quantities to overcome the alkali, and having been
worked to the end of the canal with broach, then the root canal be flooded
with a saturated solution of soda bicarbonate. The reaction will at once
remove practically all foreign substance from the canal. If the tooth
then be dried and the roots cracked open the canals show white and clean
as marble.
With the tantulum root excavator and sulfuric acid the root canal
may be enlarged more rapidly and with greater freedom from unpleasant
and sometimes dangerous conditions. The acid destroys and breaks down
disorganized organic tissue, the soda solution removing the debris without
forcing the disorganized substance through an open foramen, as many
dentists seem to fear.
If acid solution be placed in a small glass tube, and you then pour
CANAL SURGERY AND ORAL INFECTION
483
the soda solution into the tube, it will be seen that chemical action is all
on top of the acid, or only on the surface of acid exposed to the soda;
or, in other words, it does not react in the form of an explosion, the
Fig. 499. Copper band cemented on tooth to
facilitate the placing of rubber dam where
the cavity extends below the gum margin.
Fig. 500.
Showing curvature of buccal roots
of upper molar.
larger end of the canal being open and offering no resistance to the gas.
If the acid solution should pass through the foramen no further reaction
could take place than that of irritation, as is shown in Fig. 505.
Fig. 501. Shows amount of tooth structure to
be removed to get as nearly as possible in a
straight line with the foramen.
Fig. 502.
Showing curvature of roots of
lower molar.
484
APPENDIX
Fig. 504. Transverse sections of large flat
root. A. Canal filled with disorganized prilp
tissue. B. Attempt to clean canal with
drills and broaches often digs a passageway
through the disorganized canal contents. C.
By chemical methods everj vestige of or-
ganic tissue may be removed.
Fig. 505. B. Self-limiting action of sulphuric
acid solution on cancelous bone tissue. A.
Action of sodium potassium on same bone.
Fig. 506, $pme itijitrHments used for the opening of root canals.
CANAL SURGERY AND ORAL INFECTION 485
Root Canals Tilling.
By Dr. J. R. Callahan, Cincinnati, Ohio
Colophony, resin, commonly known as rosin, is obtained from tur-
pentine by distillation. In the process the oil of turpentine comes over
and the rosin remains behind. Rosin varies in color from dark red-brown
to black and white, according to its purity, and the degree of heat used
in its preparation. Chemically, it is the anhydrid of abietic acid. It has
the physical and chemical properties common to all rosins. It softens
at 176 degrees F. and fuses completely at 275 degrees F., is insoluble in
water; with difficulty is soluble in alcohol; freely soluble in chloroform,
acetone, benzone, and fatty oils.
The rosin that is best adapted to dental uses that I have been able
to find is that prepared by Barnardel for the use of the violinist. It is
a French preparation, very near the color of dentin. The formula, as
given below, makes a very thin solution. It required a long time for me
to realize the advantage in the use of a thin solution. A thick mixture
will not pentrate the tubules, nor does it give up enough chloroform to
dissolve the gutta-percha :
^ Rosin gr. xii
Chloroform oiij
n^ Ft. sol.
As we are to deal with dentin that has been
Httatomvof subjected to infection, a brief rehearsal of the his-
DentilU tological anatomy of dentin will aid us in getting
our mental eyes in the same focus.
Arthur Hopewell Smith, in his late book, " An Introduction to Dental
Anatomy and Physiology," says :
" The functions of dentin are to give substance to the tooth itself ;
to provide a centre of sensation ; to protect the pulp. Enamel is without
the pale of nutrition. The pulp is highly vitalized and the dentin is on
the borderline of the living and the dead : semi-vitalized, if one may so
speak.
" Nature would not for a moment tolerate the presence in the midst
of living tissues of a dead body like enamel. The result is therefore the
presence between the living pulp and the inert enamel, of a large area,
relatively speaking, of a tissue which is marvelous and unique. In no
other part of the body do we find an entirely tubular structure like dentin.
Its peripheral parts where it joins the inorganic enamel and cementum
486 APPENDIX
are less vitalized than in central parts. This explains the reason why
the dental tubules are not of the same caliber throughout their lengths.
They vary from 1.7 to 5 m. The diameter of the tube diminishes as
it proceeds outward, until at the peripheral region of the tooth it becomes
immeasurable. The dentin of the crown of teeth is more plentifully
supplied with living material (protoplasm) than the roots; hence the
tubes branch more frequently in the latter than in the former situation.
The tubes carry the dentinal fibrils; that is, the peripheral poles of the
odontoblasts."
It is through these dentinal fibrils that nervous stimuli are trans-
mitted to the pulp. Following the teachings of Miller and Black in the
study of carious dentin, we note among other interesting things that
caries progress along' the lines of the dentinal tubuli; that the form of
the disintegrated dentin is that of a cone with the apex toward the pulp
chamber, and that the dentin is decalcified in advance of the penetration
of the micro-organisms.
It is not likely that in the preparation of cavities we always remove
the apex of the affected dentin. In deep-seated cavities is this advisable ?
In spite of the application of strong antiseptic agents, recurrent decay
may develop and toxins finally reach the pulp.
If the remaining traces of thin layers of decayed
TIdvantaacs dentin can be thoroughly dehydrated, the application
of Rosin. of rosin solution may be of great service.
First, rosin being more or less a non-conductor,
it reduces the shock of thermal changes.
We are taught that the decalcified dentin that is to be found just in
advance of the micro-organisms in carious dentin furnishes food for the
invading germs. If the remaining decalcified dentin be saturated with
rosin, I imagine the cost of living in that region will become prohibitive.
However, if the rosin solution reaches the farthest boundaries of the
decalcified dentin through the infected area, then the micro-organisms
within the tubuli will have been engulfed within the rosin solution, and
unless the bacteria are able to liquify the rosin, they will be forever
inhibited from further activity, be they aerobic or anaerobic, in active or
spore form. I need only mention the antiseptic properties of the chloro-
form.
This, you will admit, would be a very desirable condition in which
to have a layer of decayed or decalcified dentin over the pulp, where the
removal of the layer of decay would mean the exposure of the pulp.
The most satisfactory results that I have had in capping pulps has
CANAL SURGERY AND ORAL INFECTION 487
been a flow of rosin solution over the exposure, evaporating the chloro-
form with warm air, then to cause a very thin cement to flow over the
floor of the cavity and the thin coat of rosin and allow it to harden, being
very careful to avoid pressure of any kind on the cement until quite hard.
This practice has been confined to quite small and recent exposures.
Not the least satisfactory use of the rosin solution is after more or less
thorough drying of the cavity and application of the rosin prior to the
insertion of gutta-percha filling, either as a temporary or permanent filling.
On the removal of a temporary stopping of this nature, that has been
in place a week or a month, the decayed dentin, which for any reason
may have been left in the cavity, will be found noticeably tough and hard
and dry, due to the presence of the rosin, and the sensibility of the dentin
will be materially less, showing that the dentin has been free from the
irritating efifects of acids, or, in other words, the fibrils have been in a
state of comparative rest. And after all is said, the chief function of the
surgeon is to remove the irritant and place the affected region at rest, to
the end that Nature may perform a cure.
We now come to the consideration of the time-
Koof Cfintll worn subject of root-canal filling.
Tilling* If possible, is it desirable or necessary that the
tubuli be sealed?
Dr. Hermann Prinz, whom I regard as one of the foremost among
our scientific research workers, said in a paper read before the St. Louis
Dental Society, September 2, 1912: " If the canal is not filled perfectly,
serum will seep into it from the apical tissues. The serum furnishes
nutrient material for the micro-organisms present in the tubuli of a
primarily infected root canal."
The dentin is traversed by dentinal tubuli, which
multivk number from 25,000 to 30,000 to the square niilli-
Torsmin^l. meter. The pulp in situ sends protoplasmic pro-
cesses into these tubuli, and is connected with the
peripheral tissues by arteries, veins and nerves which pass through the
main foramen and a number of small foramina (usually 2-7) present
in the apex of the tooth. According to Fischer, these accessory foramina
are found in about ninety per cent, of all permanent teeth. These anotomic
facts are not sufllciently emphasized at present. Their significance is of
great importance for the full comprehension of the pathology of sec-
ondary infection.
In an incipiently infected root canal, these dentinal tubuli and the
small foramina offer ready hiding-places for various forms of pathogenic
bacteria.
488 APPENDIX
After exhausting the nutrient material, the bac-
flCtion Of teria become attenuated, or they assume resting
Bacteria. forms. If the tubuh and the foramina are tightly
sealed, these enclosed bacteria must necessarily re-
main permanently confined in their lodging places, while if the root canal
filling leaks, the seepage of serum furnishes fresh material which offers
excellent opportunity for their renewed activities.
By continuity this secondary infection spreads along the lines of
least resistance, i. e., toward the apex, and finally reaches the pericemen-
tum. This tissue protects itself against the invading foe by a reactive
inflammation, which results in the production of a fungus growth known
as a granuloma, or in the past, as the abscess sack of pyogenic membrane.
For years the enclosed bacteria may remain dormant. At the slightest
provocation, however, overexertion, a cold, increased blood pressure,
lowered vitality, or some other cause, they may assume a most virulent
activity, resulting in the production of the so-called subacute abscess.
Based upon this supposition we are able to furnish a plausible explanation
of how these obscure secondary abscesses occur about the devitalized teeth
which at one time were pronounced cured.
In one of the most profound papers given to the dental profession on
mouth infection, Dr. Rhein says : " Unfortunately, as a profession we
must admit that most of the cases of blind abscess are the results of imper-
fect dental operations. In some cases they may be the result of bad judg-
ment on the part of the operator ; in others they may be due to ignorance
and incompetence, but a very large number of cases are attributable to
the failure of the educated dentist to give the time needed to perform an
aseptic operation and have the field absolutely free from the possibility
of future infection. This is absolutely nothing short of malpractice when
done by a dentist who knows."
We have the testimony of several investigators to the effect that it
is possible to sterilize the root canal proper, but it is an impossibility to
sterilize the infected dentin of a tooth while it remains in the mouth.
The microscope and the culture media have shown us conclusively
that we have been, and are now, leaving enormous numbers of micro-
organisms v/ithin the body with a more or less available route open to
the circulatory system where they may reach any part of the body, carry-
ing destruction to those organs or parts that may offer the most attractive
lodging place.
A most significant fact must be borne in mind in regard to the devi-
talized dentin. We have no blood current to assist in the struggle. The
dentin has aboslutely no power even to assist in repair. No granulation
CANAL SURGERY AND ORAL INFECTION 489
nor scar tissue — nothing but an inert tubular mass infected by millions of
toxin-producing micro-organisms. We must make of this infected tubular
mass an inert, harmless and stable body, including the effective closing
of the numerous foramina, to the end that Nature may be able to develop
the root mass in a healthy and vigorous peridental membrane that the tooth
may serve its several useful purposes for a number of years.
Most of us have at one time or another shared
_- - ^ , in the opinion that v^^hat the root canal might be
Requirements Of ^„ , . f ,111
Root Ghm\ nlled with mattered but little.
'""•^fl* The radiograph in the hands of the advanced
dental practitioner has brought to light evidence suf-
ficient to prove the fallacy of such an opinion. It does matter as to the
material ; it does matter as to the manner of placing the material in the
canal. The matter of prime importance is the sealing of the more or less
numerous foramina, and, as wq have no assurance that all the foramina
in a given root canal are located near the apex, it becomes our duty to
seal the whole length of each canal with a material that will search out
and seal minute canals or openings which, owing to physical conditions,
we are unable to see.
Have we a root canal filling material that will
Gtltta-Percba meet the requirements indicated above? We have
KOOt THlingS. three that may be considered. Gutta-percha and
chloro-percha in combination ; paraffin, as advocated
by Dr. Hermann Prinz and Dr. Dunning, and the combination of rosin
and gutta-percha. With the gutta-percha cone and chloro-percha you
are quite familiar. We know of many successes as well as of the many
unhappy failures with this root filling, sometimes due to faulty manipula-
tion, but often due to the fact that the root canal filling has shrunken
sufficiently to admit body fluids to the canal, or permit egress of the
micro-organisms that infested the tubuli, and in addition the gutta-percha
root fillings are often found to be saturated with decomposed and odor-
iferous substances that we are altogether too familiar with.
The paraffin root canal filling, as advocated by
Paraffin ^^- Prinz and Dr. Dunning, has many attractive
KOOtTilHngs, features, and time may prove it a most, if not the
most acceptable root filling. I have not always suc-
ceeded in getting the paraffin to the apex of the roots of upper teeth. If
the wire is too hot the paraffin will collect about the shank of the instru-
ment, and if not hot enough it does not flow to all parts of the canal.
The melted paraffin will, however, follow the paraffin oil into the tubuli
490 APPENDIX
and foramina if treated porperly. It will take time to prove its perma-
nence with the body. Our previous experiences and the experiences of
the surgeon have made us a litle shy on this point.
The technic of the rosin-gutta-percha root filling
Rosin and ^^ simple, easy, quick, and sure to seal all tubuli and
Gutta-Pcrcfta foramina that are open. Before proceeding with the
Root Tiilings. filling of the root canal, all instruments, cotton-paper
points, gutta-percha points, should be placed in the
steam chest, superheated steam being the most effective sterilizing agent.
After steaming the proper length of time, the steam is shut off from the
chest. This soon dries the instruments and points and cotton broaches.
The gutta-percha and paper points after cooling in the basket have lost
none of their desirable properties.
I have said that a root canal should be of the general shape of the
fine paper root canal driers as furnished us by the dealers. In addition
to this general form, have the mouth of each canal a decided saucer shape.
This will facilitate the placing of agents or instruments to or near the
apical foramen.
The first step, then, is the complete dehydration
DfViltfl °^ ^^^ dentin, using acetone, as advised by Dr. Prinz,
0(inaK as the dehydrating agent. After flooding the canal
with acetone, use the paper points liberally until the
canal is entirely free of moisture. Follow this with warm air. Then
hold a warm wire in the canal for a minute or two, being careful that
the wire is not hot enough to scar any part of the canal.
Right here is where many root-canal operations fail. The canals
and tubuli must be as dry as it is possible to make them, bearing in mind
that it is possible to do damage by overheating the root.
Now flood the dry root canal with the thin rosin
TntrodUCina solution, pumping it in with a wisp of cotton on a
Rosin. broach. When the canal is full of the solution, pass
a fine wire or broach to the end of the canal. Work
out all of the air that may be trapped therein. This is of vital importance.
After the canal has been flooded or pumped full of the rosin solu-
tion, dip the cotton and broach that is being used into or pick up on the
cotton, bismuth oxide hydrate. Work this into the rosin solution that is
already in the canal. This is not essential to the preservation of the fill-
ing, but makes a more distinct picture of the finer canal fillings when the
X-ray is in use.
CANAL SURGERY AND ORAL INFECTION 491
The canal point should be made of the base plate
_ . gutta-percha. It should carry no drugs nor any addi-
CiUttJI-Pcrcba tional element that will have a tendency to weaken
^^^^* or reduce the strength or rigidity of the cone, because
we wish the gutta-percha to dissolve rather slowly at
the periphery, while the attenuated centre retains rigidity sufficiently to
permit of being pushed along.
Select a gutta-percha cone that will reach to or near the end of the
canal, holding the cone with a fine foil carrier, and pass the cone care-
fully and surely about half-zvay into the canal, pumping the cone up and
down in the canal, usually from forty to sixty times, and, as it dissolves
in the chloroform, advancing the cone farther toward the apex.
The pumping motion forces the rosin solution farther into every
opening. The chloroform at the same time dissolves the periphery of
the gutta-percha cone, which, becoming more and more attentuated, slips
farther toward the apex, surrounding itself with a mixture of gutta-
percha and rosin. The rosin seals the tubuli and at the same time causes
the gutta-percha to stick tight to the canal walls and makes the gutta-
percha more stable and proof against the action of body fluids or sub-
stances.
If this does not leave the large end of the gutta-percha cone at or
near the end of the canal, place a small cone alongside or on the first
one, then, with cold steel plugger points that will go into the canals,
gently pack the mass into the canal, using warm air to soften the pro-
truding gutta-percha if necessary.
This packing forces the semi-fluid (chloro-percha and rosin) into
the unknown canals and pockets, and at the same time brings the surplus
chloro-percha to the mouth of the canal, where it may be taken up with
absorbent rolls or cotton.
In multi-rooted teeth complete the filling of each individual canal
before starting another.
Rub the steel plugger points on paraffin cake to prevent the partially
dissolved gutta-percha from adhering to the instrument. The pulp cham-
ber is to be filled with one of the cements.
You may ask : " Do you succeed in filling all
Queries canals and tubuli to the farthest extremity ? " No ;
J1n$wered« only those that are open and dry to the farthest
extremity.
Are we likely to have inflammation in the periapical region following
the closure of root canals in this manner?
The probability of inflammatory conditions in all cases depends upon
492 ' APPENDIX
the ability of the operator to read the pathological signs of each indi-
vidual case and his skill and delicacy of touch in the manipulation of the
various agents used.
Rosin and chloro-percha and gutta-percha cone is superior to chloro-
percha in three ways. First, the rosin in chloroform penetrates deeply
into the tubuli and foramina, into which chloro-percha will not enter at
all, leaving within such tubuli or foramina, upon the disappearance of the
chloroform, a more or less solid, inert, insoluble substance that enmeshes
the contents and seals the lumen of such tubuli or foramina. Second, the
rosin and chloroform causes the gutta-percha, in whatever form it may
be applied, to adhere closely to the walls of root canal or cavity. Third,
the incorporation of the rosin in the freshly made chloro-percha makes
an unshrinkable and impervious mass about the gutta-percha cone. If
gutta-percha and rosin be dissolved in chloroform and left in an open
dish or tube to dry or solidify, the rosin will rise to the surface and
harden in a crust over the gutta-percha. When the mixture is made in
the root canal, as has been suggested, the rosin in solution is held firmly
in place in the dissolved gutta-percha between the canal wall and the
cone in the centre.
We must be prepared to meet all sorts of morbid anatomical changes
in the pulp chambers, root canals and the dentinal tubuli, due largely to
constructive irritations long present in and about the tooth.
The illustrations I show are selected, each one, to assist in demon-
strating that the teeth which require root canal treatment are, as a rule,
far from being the perfect anatomical specimens that we see illustrated
in our text-books. A tooth that has lost its pulp has usually been sub-
jected for a long time to those conditions that bring about destructive as
well as constructive changes.
The rosin solution does not show in X-ray pictures until mixed with
gutta-percha, when it shows very plainly in the canals and foramina, but
not in the tubuli. Chloro-percha will not enter the tubules ; bismuth
oxide does not dissolve in chloroform, and therefore does not enter the
tubuli ; the blue stain spoken of enters the tubuli with the chloroform and
rosin solution, but does not show in X-ray pictures ; so, in order that we
might have some visible evidence of the dififusibihty of the rosin solution
through the dentin, I have resorted to color photography. To vouch for
the correctness of the pictures I have the original specimens here for
comparison. One better versed than I in laboratory technic could cer-
tainly work out a more satisfactory scheme than this.
The pulp canals of a number of extracted teeth were opened
mechanically — that is, with burs and drills — dehydrated and pumped full
CANAL SURGERY AND ORAL INFECTION
493
of the rosin and chloroform that had been stained blue. Then the gutta-
percha cones were used as has been described above.
I do not claim that this procedure gives an exact reproduction of
conditions in a tooth canal while the tooth is yet in service in the mouth.
I do claim that the specimens and the pictures give a clear and under-
standable basis from which we can work toward a reasonable ideal.
The illustrations following are shown more to explain the theory
than to prove results. There is a vast difference between filling a root
canal in an extracted tooth and one in situ.
Fig. 507. Water dropped into a dry glass tube does not go to the end of the tube on account of
entrapped air. Rosin solution should be worked to the ends of root canals with fine broach
Fig. 508. Shows what happens when long
gutta-percha canal point is forced into c^nal
without the pumping motion
Fig. 509.
(See caption under Fig. ,t;ioli
494
APPENDIX
Figs. 509 and 510. Tooth substance having
been dissolved away from root canal filling.
Shows the long minute canals that the
rosin and gutta-percha solution enters and
seals.
Fig. 511. Palatine root of upper molar en-
larged with drill, making a false pocket.
The rosin-gutta-percha solution not only
filled the false pocket, but entered the true
canal and filled it to the end.
Fig. 512.
The shaded area about the root canal filling shows the distance that the rosin has
penetrated the dentinal tubuli in this tooth root.
CANAL SURGERY AND ORAL INFECTION 495
Devitalization of the Pulps of l)ealtby Ceetb Tor Briage mork
Until recently the writer has been a sincere advocate of devitaliza-
tion of teeth to be shell-crowned for bridge abutments, and it is still
my opinion that if a tooth is properly prepared to receive the ordinary
type of shell crown the tooth will be so mutilated that the pulp in it will
die. A new type of shell crown then, the use of which does not necessi-
tate such destruction of tooth structure as to endanger the vitality of the
pulp, is a thing I receive with great gratitude.
It is fortunate that I am able to print the following excellent paper
by Dr. D. A. House. I wish to say to readers who may not appreciate the
value and importance of Dr. House's paper, that Dr. House demonstrated
the making of the crown he describes to me several years ago, and I paid
little attention to him. Do not make the mistake of inattention I made.
Every dentist should make crowns such as Dr. House describes. What
folly it is to extract one abscessed tooth and then devitalize two teeth,
fill the canals imperfectly, and insert a bridge !
J{ metboa for makind a aold €rown for Bndgework without Pulp
Devitalization.
D. A. House, D.D.S., Indianapolis
Ever striving toward accuracy and perfection to meet new condi-
tions constantly arising, the dental profession has to cope at present with
facts which, a few years ago, were neither heard of nor anticipated.
Scientific and clinical research, coupled with Roentgenology, have
proved that foci of infection exist in the dental field and not only do
exist there but, too often, are there because of faulty dental operations.
This naturally places the dental profession in a rather precarious position.
Scientific research has quite conclusively proved that neuritis, arthri-
tis, endocarditis, &c., &c., can be, and are, caused by infection being ad-
mitted into the blood stream. That there is somewhere a focus where
the infection is produced and that that focus of infection may exist at
the apex of the root of a devitalized tooth. The lesion about the tooth
may not be manifested in any way whatever. The tooth may not ever be
suspected of being in any condition other than normal ; and yet it may be
the prime source of any one of numerous conditions that make life miser-
able for the patient and can even destroy life itself.
With the aid of the radiograph these foci of infection are not only
496
APPENDIX
revealed to us almost unfailingly, but it reveals to us the cause of the
infection, and embarrassing as it is to admit it, the dental profession must
acknowledge it is often due to faulty and unjudicious operations.
If then, the above conditions do exist, and are caused to exist by
faulty technic or impossible perfection in operation, the logical procedure
is to do the operation in a manner by which the faulty or impossible
feature is eliminated.
When a shell crown is indicated in the construction of a bridge, in-
stead of pulp devitalization in order to prepare the natural tooth crown
in such a manner that the crown band may be adjusted as accurately as
possible around the cervix of the tooth, which is practically impossible to
do accurately enough to prevent subsequent irritation of the gingivae, I
have adopted the following technic for crown construction. This method
Fig. 513.
Fig. 514.
not only eliminates pulp removal with is dangerous sequalae but leaves
the gum tissue in its natural normal condition, instead of producing a
condition conductive to disease.
Having noted the results of this form of crown construction for a
number of years, I use it exclusively where the shell crown is indicated
for bridge abutments, not only on molars but bicuspids, also where
esthetic considerations do not contraindicate its use. The technic being
similar in either case, I will illustrate it in the construction of the molar
crown only.
The normal form of a molar or bicuspid naturally makes the entire
circumference convex. Because of this convexity, the diameter differs
CANAL SURGERY AND ORAL INFECTION
497
from the occlusal surface to the cervix (Fig. 513). In order to retain an
anatomical form of the crown when completed, and to have it sufficiently
heavy for rigidity, it is necessary to grind the natural tooth to a point
Fig. 517.
Fig. 519.
Fig. 518.
^S»»*~««8S8^
Fig. 520.
about midway between its greatest diameter and the gingival margin.
(Fig. 514.)
There is seldom any discomfort to the patient as the enamel is only
partially removed. Care should be taken not to injure the contact point of
the approximating tooth.
498
APPENDIX
Having ground the tooth conical in form, an impression is taken,
model made and a pure gold, 34 gauge, band fitted to the model in the fol-
lowing manner: A piece of gold curved in form like Fig. 515, either
by cutting or passing a straight piece through the gold roller with one
set screw advanced a little closer than the other, when formed into a band
will be conical in shape (Fig. 516), and is fitted to the model closely and
Fig. 521.
Fig. 522.
Fig. 523.
made to extend just to the point where the tooth has been ground (Fig.
517). After being fitted to the model, it is fitted on the tooth in the
mouth. Be sure to extend it to all points where the enamel has been re-
moved. It should be made to fit the tooth perfectly by burnishing, and
the occlusal end should be short enough not to interfere with the closing
of the teeth.
It is removed in a plaster impression and before pouring the model
a little baseplate wax is flowed on the inner surface of the band, so later,
by slightly warming it, it is easily removed from the model.
With the band in its proper position on the model, a second band of
29 or 30 gauge, 22-K. gold is contoured and fitted over the first band.
Fig. 518, noting especially the original contour and contact point of the
CANAL SURGERY AND ORAL INFECTION 499
natural tooth. The second band should be about 1/32 of an inch shorter
at the cervical margin than the first band, so that after uniting the two
with 22-K. solder the cervical end may be finished to a sharp edge to pre-
vent any thick margins and to facilitate possible future burnishing.
The space between the bands having been perfectly filled with solder,
it is now ready for final adjustment to the tooth. The occlusal surface
of the tooth having been ground sufficient for a heavy occlusal surface
on the crown (Fig. 519), the band is trimmed just even with the occlusal
plane. A piece of pure gold, 34 gauge, is soldered on the end of the band,
which is then placed on the tooth. The pure gold end is now burnished
to the ground occlusal surface of the tooth.
A wafer of softened inlay wax (Fig. 520) is then placed on the
occlusal surface of the crown and the patient instructed to "bite." After
the wax is chilled, the band and wax are removed, the wax securely at-
tached and carved (Fig. 521). Next invest and cast. Should the casting
form an imperfect attachment to the crown, unite the parts with solder.
This part of the technic being completed, it is ready for replacement
on the tooth (Fig. 522) for final impression and subsequent finishing of
the bridge in whatever manner appeals to the operator.
While this form of crown construction has been most gratifying
in all cases where vital teeth are involved, I can most heartily endorse it
in cases where a convergence of teeth, due to the long loss of the missing
teeth (Fig. 523) has entirely changed their axial relations.
As I said in a preceding paragraph, this form of crown construc-
tion can be used for bicuspids when esthetic reasons do not interfere ; it
can even be carried to the lower cuspids under similar conditions, the
technic being similar in all instances.
For one who prefers using the casting process whenever possible,
the technic can be changed as follows : After the first pure gold band
is fitted, the occlusal end of pure gold is soldered to this, the contour and
occlusion are formed in inlay wax and the whole cast in one operation
instead of adding the second band of 22-K. gold. But, because of the
accurate fitting of the first band, I find that the shrinkage following cast-
ing is such as to make replacement of the crown on the tooth for the final
impression more difficult than where the double band method is used.
In the above method it is not only possible to construct a most
serviceable substitnte for the natural tooth but it is done without sacri-
ficing the vitality of the pulps of natural teeth and without jeopardizing
the health and gum tissue and pericemental membrane surrounding the
teeth.
500 APPENDIX
(Conclusion
To conclude this chapter, I now quote from a paper read before the
Chicago Dental Society. As a hen lays eggs primarily " for personal re-
lief " rather than the benefit of humanity, I admit I give the following
for the same reason. I want to advise physicians, dentists and radiog-
raphers so we may all meet this problem of pulp canal work and systemic
infection to the greatest possible advantage of the patients in our care :
To Physicians*
1. Shoulder your share of the responsibility for the occurrence of
local foci of infection in the mouth.
2. Do not advise the the extraction of two teeth because one tooth
is abscessed — nor all teeth because some are abscessed.
3. Never advise extraction without first making radiographs.
4. Have an expert read the radiographs, or pass on your reading,
until you have become expert.
5. Do not say all teeth with the pulps removed should be extracted,
for we do not know that this is true.
6. Do not forget that teeth have an important function. This is just
as much a truth as it ever was. Keep it in mind.
7. Wake up to the fact that to learn what you should know of this
subject you must hear what dentists have to say about it. Invite them to
lecture at your meetings and in your schools.
8. Keep this in mind : The dentists of the United States have
developed a Research Commission, which will rank with the Carnegie and
Rockefeller Laboratories for research.
9. Remember that most of the diseases of infancy were once at-
tributed to teething.
To Dentists
1. Do not jiggle about, and try to sidestep the situation.
2. Support the National Research Commission with your heart,
mind and money.
3. Let the apical excision and curettement operation become a
common one, not an uncommon one.
4. Admit that the destruction of pulps has been ruthless, and as
you admit it, correct the mistake.
* August, 1915, Dental Review.
CANAL SURGERY AND ORAL INFECTION 501
5. Develop a new and better bridgework, Bridgework is not to be
relegated to the scrap heap — but it should be modified.
6. Never expect to hear again the man who came to your meeting
and said he " filled all canals to the apex."
7. Admit it is impossible to reach and fill to the apex all canals.
No man can do it by the methods you now use.
8. Look to the National Research Commission to learn if you
should extract teeth when it is impossible to fill the canals to the end.
9. Know that it is not a crime to fail to fill a canal perfectly, but
that it is a crime not to try to fill it.
10. Charge for the treatment of teeth on a time basis and render a
bill whether you save the teeth or not.
11. Change your slogan from "Save Teeth" to "Save Teeth
■ — But Never At The Expense Of Producing A Chronic Abscess."
12. Do not depend on medical men to make and read your radio-
graphs for you.
To Radiographers
I. Do not read a diagnosis into every radiograph whether it is
there or not. Learn to say, when it is the case, " The radiograph shows
me nothing."
2. Believe in the infallibility of the radiograph, knowing it is the
product of definite and unchanging chemical and physical laws, but
realize that, unless you know these laws, it may mislead you.
3. Never deny the assertion that radiographs have unfortunate
limitations. Though the radiograph is the greatest single aid to dental
diagnosis, it nevertheless fails often to show us what we want to see.
4. Understand the necessity of making more than one radiograph
of a single case. When in doubt, verify with another radiograph.
5. Distrust any radiographic finding that is not backed up by the
clinical evidence.
6. Do not profess to be a dental radiographer unless you are a
dental pathologist.
7. Try not to blame the radiograph for your occasional silly inter-
pretations of it.
8. Know the list of the common misinterpretations of radiographs.
(Appendix, Chapter VL)
9. Understand that it does not fall within the province of radiog-
raphers to be harsh critics of either dentists or physicians. Your position
is a delicate one. Handle it with patience, kindness, coolness and hon-
esty. Do not try to turn things upside down all at once.
502 APPENDIX
To Physicians, Dentists and Radiographers All!
Let tis all appreciate the necessity for team work. The tendency to
clannishness in the human being is fundamental. The boys of the east
end hate the boys of the west end. Knowing this human fault of clan-
nishness, let us guard against it.
When a man of one profession meets a bonehead of another, do not
attribute the osseous condition of the man's head to the profession of
which he is a part.
Let us realize that to the best of our present knowledge, if teeth are
properly treated they do not abscess.
Therefore, they must be treated properly.
If teeth are to be treated properly there must be a raise in the average
fee charged.
People turn from good dental treatment on account of the cost, and
indeed and actually very many of our American people cannot afford to
have their teeth treated properly. What is to become of them? Some
one answers, " Extract their teeth." The answer is that the medical pro-
fession has tried to persuade women not to wear corsets ever since we
can remember, but women wear them just the same. Likewise, it will
be found impossible to induce poor people to give up their anterior teeth.
They will go to the dental quack. And what if we expose the quack and
destroy him? It would be a good, though difficult, thing to do, but the
point is that we do not want to extract teeth, we want to save them.
The solution of the whole problem lies, not in the development of
an inexpensive method of treating pulp canals, which it seems to me, is
impossible, but in a publicity campaign which will lessen the necessity for
treating canals.
Do people really know that they save health, pain, money and time by
having their teeth filled before they ache ? In a hazy sort of a way they
do ; but they do not know it well enough, and it is our fault that they do
not. We must teach them.
Our slogans are changing. We no longer say, " Swat the fly," we
say, " Prevent the fly " ; we do not say, " Reform the criminal," but " Pre-
vent the criminal." We talk little about " curing tuberculosis," but much
of " preventing it." So let us not only improve our pulp canal treatment
work, but do the bigger thing — try to prevent the conditions which
make pulp canal work necessary.
INDEX
Abortion 277
Abscess,
Alveolar 186
Chronic 405
Dentoalveolar 185
Destruction of Tissue in
187, 412, Fig. 452A
How to Avoid 442, 472
Multirooted Teeth 190
Number of Teeth Involved 189
Of Crowned Teeth 191, 452
Opening on Face 253, 257, 419
Pericemental 195
Photograph of 373, 379
Probable Causes 472
Pyorrhea Alveolaris, Differential
Diagnosis 193
Treatment of 399, 463
When Cured 381, 463, 465
Absorption of Teeth (See Resorption)
A. C 2, 9, 11, 24
Acid Fixing Bath 78
Acid, Sulphuric 479
Advice to
Beginners in Radiography (See
the Preface) 128
Dentists 500
Physicians 500
Radiographers 501
Alopecia 278, 429
Alternating Current 2,9,11, 24
Alveolar Abscess (See Abscess)
Ammeter or Amperemeter 32
Ampere 4
Amputation of Apex of Tooth
Root 201, 413, 419, 468
Angle of X-rays 99
Anode 41, 42
Ankylosis 247, 263
Anodyne • • 447
Anomalies 230
Anterior Palatine Foramen 364
Anti-Cathode 41, 42
Antrum of Highmore 234
Foreign Body in 238
Pus in 234, Fig. 451
Radiographing of 341
Apical Foramen,
Fining to 175, 437
Filling Through 408, 446
Multiforamen 439, 473
Apicoectomy ..201, 413, 419, 468
Apparatus Radiographic. .. .14, 295, 320
Appendicitis 416
Aprons, X-ray Proof 286
Armature 9
Arsenical Necrosis 231, 422, 472
Arthritis 416, 456
Articulation, Temporo-Mandibular,
242, 266
Artificial Roots 213
Asepsis 456, 471
Assistant Anode , 46
Attachment, Gilmore 375
Average
Canal Filling 438
Dentist 440
Azo Photographic Printing Paper.. 83
Bacteremia 416
Bacteria, Cultures of 472
Bad Canal Work 437
Benoist Penetrometer 346
Bi-anodal X-ray Tubes 44
Bismuth Paste 199
Blood Supply. 266
Bone Eburnation 382
Bone Regeneration... 203, 381, 400, 465
Bone "Whorls" 214
Boxes, View 136, 406
Bridgework 209
On Vital Teeth 498
Bromide Paper 347
Broken
Broach in Canal 205
Tooth ......205, 208
Burn, X-ray (See Dermatitis)
Cabinet, Protective Lead 280
Calculus 194, 217
Callahan
Papers by 474
Solution 485
Technic for Canal Filling 485
Canal Filling,
After-pain 447
Average 438
Asepsis vs. Mechanical Perfec-
tion 383, 456
Callahan's Solution 485
Causes of Failure 458
Chart of 438. 452
Difficulty 437
Economics 453
Encapsulating Apex 446
Failures 437
Gutta Percha 267
In Molars 458
In Teeth Other than Molars... 437
Kinds Seen in Radiographs 408
Materials 401
Muhiforamen 439, 473
Preparation for 474
Proprietary, Pastes 401
Radiography of . ! 370, 447
Repeated Efforts 439
Rosin Solution 485
Technic 485
To Apex 175, 437
Through Apical Foramen 408, 446
What Is Bad 447
Canals of Teeth,
Enlarging 175, 210, 460 474
Filling 175, 485
Canal Surgery (See Canal Filling)
Cancellous Spots in Bone Fig. 401
Cancer 274
Carelessness with X-rays 426
Caries,
Dental 269, 420
Of Bone 231
Cathode 42
Collars 2)2)7
Stream 48, 49, 331
Cement 403
Cementoma 214, Fig. 431
Chair, Radiographic 112
Charts,
Conditions Indicating Extraction. 415
Dr. Best's 472
Educational 452
Evidence of Infection 410
Ionization 470
Kinds of Canal Fillings 408
Milliampere-second 355
Showing Treatment Indicated. . . . 412
Cholecystitis 416
Circuit, Electric 10
Coil,
Faradic (See Faradic Coil).
High Frequency (See High Fre-
quency Coil).
Induction (See Induction Coil).
Interrupterless (See Interrupter-
less Coil).
Color of X-ray Tube. . . .51, 52, 326, 332
Combination X-ray Tube 337
Commutator 9
Compression Cones and Dia-
phragms 62), 64, 302
Condenser 34
Conductors, Electric 1
Congenital Absence of Teeth (See
Missing Teeth),
Conservation of Dental Pulp. .442, 495
Contact Lantern Slides 354
Continuance of Infection After Ex-
traction 464
Converter, Rotary 36
Coolidge, X-ray Tube 331
Coronoid Process Fig. 406
Cranial Sinuses 341
Crooke's Tube 41
Crowned Teeth 181, 191, 452, 495
Cultures 472
Culture Media 472
Currents 2, 53
Cut Outs (See Fuses).
Cutting of Teeth, Delayed 148
Cycle 2
Cyst,
Bone 218
Dentigerous 222
Danger,
Influence of Fees 426
Of Electric Currents 430
Of the X-rays 273, 423
To Operator 287
To Patient 288
Dark Room,
Lantern 68
Tips in Technic 350
Ventilation .. : 348
D. C 2, 9, 11, 19, 295
Death from X-rays 275, 276
Deciduous Teeth 157, 161, 162, 163
Delayed Eruption of Teeth 148
Densities, Recorded on Radiograph
136, 138
Dental Caries 269, 420
Dental Pulp,
Conservation for Bridgework. . . . 495
Electric Test 394, 395
Test for Vitality 394, 395
Dental Stereoradiographs 298, 431
Practical Value of 314
Technic for Making 310
Dental X-ray Machines 320
Denticles 250
Dentist,
Advice to 500
Average 440
Educating 445
Dentoalveolar Abscess (See Ab-
scess),
Pain in 405
Dermatitis 273, 274, 290, 425
Developing Box 129, 134
Developer 75
Choice, of 128
Hydrochinon 75
M. Q 75
Pyro 76
Temperature 76
11
Development,
Of Negatives 74, 128,351
Of Prints 83
Of Teeth 263
Destruction of Tissue, Bony and
Tooth 187, 415
Diagnosis 360
Diagram,
Cathode Stream 48
Compression Cone and Dia-
phragm 64
Coolidge Tube 334
High Frequency Coil 36, 38, 90
Induction Coil 20, 32, 33, 34, 86
Interrupterless Machine 39, 92
Mechanical Interrupter 28
Pose for Radiographs.. 70, 99 to 102
Pulp Conservation 442
Rheostat 25
Shunt 45
Stereoscopic Work 302
Switch 22
Valve Tube in Use 54
X-rays 48
X-ray Tubes 46, 57
Diaphragms and Compression Cones,
61, 64, 302
Differential Diagnosis, Pyorrhea
and Abscess 193
Differentiation, Primary and Sec-
ondary Teeth 161
Difficulty of Canal Surgery 439
Direct Current 2, 9, 11, 19, 295
Disease, Systemic 416
Diseases of Eye, Ear, Nose and
Throat : 416
Dislocation of Condyle 242
Distance Between Target and Film
or Plate 124
Distance Between X-ray Tube and
Patient 96, 424
Disto-Buccal Root of Upper Mo-
lars 391
Doctor,
Best's Charts 472
Callahan's Papers 474
House's Paper 495
Hunter's Paper 268
Johnson's Editorial 357
Leach's Film-Holder 116
Lucas' Technic 468
Ottolengui's Words 407
Rhein's Technic 177
Van Woert's Technic. .. 132, 134, 350
Dose of X-rays 288, 424
Dry Plates 65
Drying,
Immediate 132
Of Negatives 80
Of Prints 84, 353
Duration of Exposure. 71, 124, 355, 424
Dynamos 9
Ear, Pain in 228
Eburnation, Bone 382
Economics 1 70, 453
Editorial, Dr. Johnson's 357
Writer's Reply 358
Education,
In Radiographic Work (See the
Preface) 294
Of Dentists 445
Of Public 441
Electric Current, Danger ci 430
Electric Pulp Testing,
Electrophobia 396
Liability of Accident 396
Limitations 395
Technic 394, 395
Electricity 1
Electrolyte 17, 21
Electromagnets 7
Electrophobia 396
Elementary Radiography...! to 85, 319
Empyema of Maxillary Sinus 234
Encapsulation of Root End. . .408, 446
Endocarditis 416
Enlarging Apparatus 433
Enlargement 433
Enteritis 416
Ethmoid Cells 234, 341
Evidence of Infection in Radio-
graphs,
Chart of 411
Examination of Mouth 398, 416
Example, Horrible 389
Exostosis, Dental 214, 384, 41 1
Exposure,
For Prints 83, 138
Of Patient Time Limit 288, 424
Long with Big Outfit 356
Short with Small Outfit 356
Time of, for Negatives 71, 124
Extra-Oral Radiographs 94, 349
Extraction of Teeth 162, 168
Chart Indicating 415
Continuance of Infection After. . 464
Few at Time 464
Eye, Disturbance of 172, 469
Facial Fistula.. 253, 257, 419
Facial Neuralgia (See Neuralgia).
Failures in Canal Work, Causes of. 458
Fallibility of X-rays 357
Faraday 8
Faradic Coil (See Electric Pulp
Testing).
Fatality from X-ray Lesions. . .275, 276
Faults in Negative 352
Ferrotype 353
Field 9
Filling (See Canal Filling).
Encroaching on Pulp 181, 378
Large 395
Filling Materials for Canals 401
Film,
Description of 66
Methods of Holding in Mouth... 109
Mounts (See Radiomount)
Placing Outside the Mouth 349
Protection of 297, 346, 350
Radiographs, Advantages of 135
Special X-ray 66, 96
Film Holders 311
Ketcham 347
Kny-Sheerer 305
Leach 116
Stereoscopic 435
Van Woert 350
Filter 289, 424
Fistula on Face 253, 257, 419
Fistulous Tract 199
Fixing,
Box 78
Of Negatives 11, 351
Of Prints 84
Fluorescence of X-ray Tubes,
51, 52, 326, 332
Fluoroscope 55, 143, 144
Foot Switch 427
Foramen,
Anterior Palatine 364
Mental 363
Foreign Bodies 202
In Antrum 238
Fracture,
Of Jaw 244
Of Tooth 208
Friedlander's Shield. 63
Frontal Sinuses 234
Intensifier 344
Pose for 341
Gagging Ill
Gastric Ulcer 416
Generator 9
Gilmore Attachment 375
Gloves 286
Granuloma (See Abscess)
Grounding Electric Current 120
Growing Cultures 472
Guide to Treatment by Radiographs
(Chart) 412
Gutta Percha,
As Canal Filling 176, 267
Non-irritating 176
Hair, Loss of 278, 429
Headache 260
High Frequency Coil,
Description of 33, 322
Diagram of 36, 38, 90
Technic Involved in Use of. . .35, 90
Holder, Film 311
Ketcham 347
Kny-Sheerer 305
Leach 116
Stereoscopic 435
Van Woert 350
Holding Film in Mouth 109, 426
Horrible Example 389
Hydrogen X-ray Tube 340
Hydrometer -21
Hyoid Bone 368
Hypercementosis (See Cementoma)
"Hypo" ■ 78, 19
Hypochondriac 261
Idiopathic Neuralgia 251
Ignorance with X-rays 426
Illuminating Boxes 136, 406
Immediate Drying of Negative.... 132
Immunity 290
Impacted Teeth.. 168, 206, 259, 262, 417
Indication for Root Resection. .413, 419
For Extraction 415
Induction Coil,
Description of 15, 323
Diagrams of 20, 32, 33, 34
Technic Involved in Use of.... 86
Infallibility of X-rays 358
Infection,
About Third Molar 418
Continuance After Extraction... 464
Elimination Without Extraction. 463
Evidence of, in Radiographs. 381, 411
Local Foci 272, 399, 462
Metastatic 272, 416, 456
Oral Foci (See Local Foci).
Periapical (See Local Foci).... 410
Pyorrheal 464
Systemic (See Metastatic).
Treatment of 399, 465
When Overcome 400, 465
Inferior Dental Canal 252, 365
Inflammation About Bridge 211
Inoculation 472
Insanity 256, 277
Insomnia 256
Installation 15, 36
Insulation 7, 27
Intensifier 81
Intensifying Screens 127, 344
Interpretation of Radiographs. . 136, 357
Mistakes in 361
Interrupterless Coils,
Description of 38, 320
Radiographs Made with '. . . 356
Technic Involved in Use of. 92 to 94
Interrupters 17
Intra-Oral Radiographs 94
Inverse Current 53
Inverted Teeth 172, 173
Involvment of Pulp, Treatment to
Avoid ...; 442
lodin. Treatment with 466
Ionization,
Case Treated 467
Chart, Technic 469, 470
IV
Jumping the Bite 263
Kassett 345
Kilowatt 5
Kilowatt-Hour 5
Kinds of Canal Fillings 401, 409
Lame Teeth 184
Lantern Slides 354
Large Plate Negatives, Advantages
of • • 135, 392
Lassitude 278
Lead Cabinet 280, 426
Lead Screen 280, 296
Leukemia 277
Liability for Accident 426, 430
Life, Loss of 275
Lighting of X-ray Tube,
With High-Frequency Coil 91
With Induction Coil 89
With Transformer 93, 94
Limit of Exposure 288, 424
Lingual Tubercle 369
Local Foci of Infection. . .272, 399, 462
Locked Jaw 262
Lower Anterior Teeth, Radiography
of 112
Lower Posterior Teeth, Radiog-
raphy of 108, 110
Ludwig's Angina 253
Luxation 242
Machines, Dental X-ray 320
Magnetism 5
Magneto 9
Making,
Crowns for Vital Teeth 495
Cultures 472
Dental Radiographs 65, 85
Lantern Slides 354
Negatives (See Negatives).
Photographic Prints 83, 353
Plastic Radiographs 317
Radiographs of Sinuses 341
Stereoradiographs 303
Malformed Teeth 230
Malposed (See Impacted Teeth).
Manufacturers 66, 297, 445
Mastoid, Pose for 344
Materials, Canal Filling 401,485
Maxillary Sinus (See Antrum).
Maxillary Suture 266
Media. Culture 472
Mental Foramen 363
Metastatic Infection 272, 416, 456
Meters 32
Methods of Holding Film in the
Mouth 109
Milliampere Second,
Definition of 355
Dose of X-rays 423
Exposure Table 355
Missing Molars 151
Missing Teeth 148, 156, 157, 266
Mistakes,
In Canal Filling 458
In Interpretation of Radiographs 361
Motor n
Moisture, Protection of Film from,
97, 350
Molars,
Filling Canals of 458
Impacted Third. 168, 206, 259, 262, 417
Lower, Radiography of 108, 386
Missing 151
Upper Radiography of 99,390
Mounts, Film (See Radiomounts)
Mouth, Examination of 398,416
Myelosarcoma of Lower Jaw 226
Nasal Cavity Spots 365
Necrosis 231, 365, 368
Negatives,
Densities Recorded in 136, 407
Development of 74, 130, 350, 351
Drying of 80, 130, 132
Faults in 352
Fixing of 11, 351
Intensification of 81
Marking of 141, 451
Reducing of 81
Scratching 135
Washing of 79, 132, 350
Nephritis 416
Neuralgia, Facial .... 160, 180, 249, 392
Neurasthenia 256
Neuritis 416
Neuroses 256
New Standards in Canal Work 440
New Words, Dr. Ottolcngui's 407
Non-Conductor 2
North Pole of Magnet 6
Nostrils Fig. 403
Odontoma 152, 156, 228, 229
Ohm 3
Oral Foci of Infection (See Local
Foci).
Orthodontia 163, 164
Oscillimeter 54
Oscilloscope (See Oscillimeter).
Osteology 263
Osteoma 227
Osteosclerosis 382
Overhead Wiring 327
Pain,
After Canal Filling 447
Of Dentoalveolar Abscesses 405
Of X-ray Lesions 277
Palatine Foramen 364
Paper,
Bromide , 347
Photographic 83, 347
Radiographs on 347
Parallel Spark (See Terminal Spark
Gap) 43
Patients, Limit of Exposure for
288, 424
Penetration of X-rays 56
Penetrometer 55, 346
Perforation of Teeth 179, 375
Periapical Infection (See Abscess) 410
Treatment of 272, 399, 462, 464
Pericemental Abscess 195
Pericemtitis, Chronic 184
Perspective 142, 144, 298
Phase 319
Phenol-Sulphonic Acid, Treatment
with ••• 465
Photograph of Abscess 373, 379
Photographic Paraphernalia Needed,
Photographic Prints,
83, 84, 137, 138, 353
Physical Condition 400
Physician,
Advice to 500
His position 463
Placing Film Outside the Mouth... 349
Planted Teeth • 212
Plastic Radiography 317
Plastic Stereoradiographs 318
Plate Changers 300
Plates and Films,
Advantages of Large Plate Neg-
ative . 135, 392
Fogged 352
Photographic Ob
X-ray 66, 96
Potassium and Sodium, Treatment
with 477
Pose for Making Radiographs,
Of the Antra of Highmore. .117, 341
" Of the Ethmoid Cells 341
Of the Lower Anterior Teeth 112
Of the Lower Molar and Bicuspid
Region 108, 110
Of the Upper Anterior Teeth 103
Of the Upper Molar and Bicuspid
Region 98
Of the Sphenoids 341
With the Film Outside the Mouth. 349
Position of Film and Direction of
X-rays 347
Position of Film in the Mouth.. 94, 95
Positive Wire, Test for 19
Positives 83
Potential 2, 3
Pregnancy 277
Preparation of Canals for Filling. . 474
Prescription 447
Primary,
Current 11, 27, 33
Teeth (See Deciduous Teeth).
Winding 11, 27, 33
Prints, Photographic 137
Development of 83
Drying of 84, 353
Exposure 83, 138
Fixing of 84
Washing of 84
Probing 199
Process, Coronoid Fig. 406
Proprietary Canal Filling Materials. 401
Protection 287
Apron 286
Box 297, 346
Cabinets 280, 426
Gloves 286
Of Films 297, 346, 350
Points in for Operator 287, 427
Screens .....280, 296
Shield 59, 285
Spectacles 286
X-ray Tube 285
Psychoses 256
Public Education 441
Publicity 445
Pulp (See Dental Pulp).
Pulpitis 421
Pulp Stones 179, 384
Pulp, Test for Vitality 394
Punctured X-ray Tube 52
Purchasing a Radiographic Outfit. 292
Pyorrhea Alveolaris 193, 464
" Pyro " 76
Radiodontia 85
Radiographers, Advice to 501
Radiographic Appearance of
Anterior Palatine Foramen .... 364
Antra 235
Canal Fillings 401, 408
Canal Fillings Short of Apex. 369, 438
Cancellous Spots in Bone Fig. 401
Carious Cavity 420
Coronoid Process of Mandible,
Fig. 406
Cyst 220 to 225
Disto-buccal Root of Upper Mo-
lars 391
Fistulous Tract 199
Granuloma (same as Abscess).
Hyoid Bone 368
Inferior Dental Canal 365
Mental Foramen 363
Nasal Cavity 365
Nostrils Fig. 403
Odontoma ._ 152, 228, 229
Osteosclerosis 382
Pyorrhea 193
Spinal Column 368
vi
Radiographic Outfit, Purchasing a. .292
Radiograph or Radiogram 65
Radiographs,
Extra-oral 94, 349
Intra-oral 94
Interpretation of 136, 357
Made Direct on Photographic
Paper 347
Mistakes in Interpretation 361
Preparation of, for Study with
Stereoscope ^ 311
Technic for Making 85,341
Treatment Guided by 413
Radiography,
Dental 85 to 319
Elementary 1 to 85
Plastic 317
Stereoscopic 298 to 319
Radiography of.
Canal Fillings 369, 401
Canal Filling Materials 401
Cements 403
Lower Anterior Teeth 112
Lower Posterior Teeth 108, 110
Molars 99, 108, 386, 390
Sinuses 341
Upper Anterior Teeth 103
Upper Posterior Teeth 98
Radiolucent 407
Radiolucency 407
Radiopaque 407
Radiopacity 407
Radioparent 407
Radioparency 407
Radiomounts 130, 131, 132, 133
Radium Rays 291
Reading Glass 393
Reading Radiographs (See Inter-
pretation of Radiograph).
Records,
Of Densities in Radiographs. 136, 138
Radiographic Records 268
Rectifier 24
Reducer 81
Regeneration of Bone,
203, 381, 400, 465
Reproductions . 137
Requirements of a Radiographic
Outfit 295
Research Work 263
Resection,
Of Inferior Dental Nerve 252
Of Mandible 247
Of Tooth Roots (See Root Re-
section) .
Resorption of Teeth 157, 165
Retained Deciduous Teeth 157
Rheostat 25
Rigg's Disease (See Pyorrhea Al-
veolaris).
Roentgen,
Ray (See X-ray).
\Vm. Conrad 49
Words (Also See the Preface) . . 49
Root End, Encapsulation of 446
Root Resection (Apicoectomy),
A Case 468
Necessity of Radiographs 419
When Indicated 412, 419
Roots of Teeth,
Absorption of (See Resorption),
Amputation of 201, 413, 419, 468
Artificial 213
Forming 160
Fracture of 208
In Antrum 238
Radiographed for Bridgework. . 209
Rosin Solution 485, 486
Rotary Converter 36
Ruhmkorff Coil (See Induction Coil).
Salivation 350
Secondary,
Current ....11, 27, 33
Dentin .....180, 442
Rays 57, 63, 289
Winding 11, 27, 33
Shield for X-ray Tube (See Pro-
tection Shield).
Short Circuit 19
Short Teeth 380
Shunt 42
Sinus, Pus (See Abscess).
Sinuses, Cranial 341
Sinuses, Radiography of 341
Skiagraph, or Skiagram.. 65
Slides, Lantern 354
Slogan 444
Sneezing • 422
Sodium and Potassium, Treatment
with 477
Soft Tube Technic 349
South Pole of Magnet, 6
Spark Gap,
Current or Coil Regulating. . .35, 36
Inverse 52, 53, 56
Parallel (Same as Terminal).
Series 52, 53
Terminal 20, 35. 36, 39, 43, 44
Tube Regulating 45, 49, 33C
Spasm, Facial Muscles 260
Specialists in Radiographic Work,
292, 294
Spectacles 286
Sphenoid Cells 341
Spinal Column 368
Squeegee Board 3o3
Stands, X-ray Tube.... 59, 60, 284, 296
Static Machine 14
Stereoradiographs,
Plastic 317
Technic for Making 303
Stereoscope 298, 299
Stereoscopic,
Radiography 144, 298
Table 301
Tube Stand 301, 303
Sterility 277
Sterilization, Technic of 471
Stones,
Pulp ..179, 384
Salivary 217
Supernumerary Teeth 167
Suppuration (See Abscess and
Pyorrhea) .
Switches 17, 427
Synchronous 39
Systemic Disease 416
Tables (See Charts).
Target .; 41, 42, 333
Distance of Skin to 424
Technic, ■■
Callahan for Canal Filling. .474, 485
Dark Room Pointers. .135, 350 to 354
For Covering Films 97
For Culture Making 472
For Developing 74, 128
For Drying Negatives Immedi-
ately 132
For Holding Film 109
For Ionization 469, 470
For Lighting X-ray tube.
89, 91, 93, 94
For Making Crown on Tooth
with Vital Pulp 495
For Making Dental Radiographs,
85 to 136, 341 to 357
For Making Dental Negatives
for Immediate Use 132
For Making Electric Test for
Pulp Vitality 394, 395'
For Making House Crown 495
For Making Lantern Slides 354
For Making Negatives 74, 128
For Making Plastic Radiographs 317
For Making Photographic Prints,
83, 353
For Making Radiographs. . .65 to 85
For Making Radiographs of
Sinuses 341
For Making Stereoradiographs. . 298
For Sterilization 471
For Using Coolidge Tube 334
For Using High Frequency Coil 90
For Using Induction Coil 86
For Using Interrupterless Coil.. 92
Mistakes in Pulp Canal 458
Pointers in 135, 345 to 356
Pulp Canal Surgery 474,485
Soft Tube 349
Van Woert 132, 134
Teeth,
Abscess of (See Abscess).
Absorption of (See Resorption).
Anomalies 230
Canals of. (See Canals).
Caries of. Hidden 269
Crowned 181, 191
Cutting Delayed 148
Deciduous ....151, 157, 161, 162, 163
Delayed Eruption 148
Development of 263
Differentiation Between Primary
and Secondary 161
Enlarging Canals of,
176, 210, 460, 474
Eruption of. Delayed 148
Extraction of 162, 168, 415, 464
Filling (See Canal Filling) . .181, 378
For Bridgework 209, 495
Forming Roots of 160
Fracture 208
Impacted 168, 206, 259, 262, 417
Lame 184
Malformed 230
Missing 14g, 151, 156, 157, 166
Moving 163, 164
Planted 212
Primary (See Deciduous).
Resorption of 157, 165
Retained Deciduous" Teeth. . 157
Roots of (see Roots).
Short 380
Supernumerary 167
Tumor of 214
Unerupted, Brought into Posi-
tion 165, 418
What Is Straight Through. .Fig. 389
Temporary Teeth (See Deciduous
Teeth).
Tempo ro-Mandibular Articulation,
242, 266
Terminal Spark Gap,
20, 35, 36, 39, 43, 44
Tesla Coil (See High Frequency
Coil).
Test,
For Polarity of Induction Coil.. 41
For Polarity of Lead Wires on
D. C 19
For Pulp Vitality 394
Therapeutic Agent, X-ray as 294
Thinking, Where It Leads Us 441
Third Molars (See Molars).
Tic Douloureux (See Neuralgia).
Tic, Facial Gesticulatory 260
Titubator 78
Tract, Fistulous 199
Transformer (See also Interrup-
terless Coil) 11
Trayrocker 78
Trays for Developing and Fixing
74, 350
Treatment,
Guided by Radiographs 413
Of Infection 399, 400, 465
Treatment with,
lodin 466
Ionization 469, 470
Phenol-Sulphonic Acid 465
Resection 201, 413, 419, 468
Sodium and Potassium 477
Trigeminal Neuralgia (See Neu-
ralgia).
Tube, Valve 54
Tube, X-ray 41
and Patient, Distance Between
96, 424
Bi-anodal 44
Color of. 51, 52, 326, 332
Combination ZiJ
Coolidge 331
Crooke's 41
Hard 42
High 42
High-Frequency 57, 58
Hydrogen 340
• Inverse in 53, 90
Low 42
Properly Lighted 50, 51
Puncture of 52
Rack 58
Shield 59, 285
Soft 42
Stand 59, 63, 2S4, 296
Vacuum 41, 42
Vacuum Regulator .45, 331
Vacuum to Buy 340
Tumor 214, 224 to 229, 250
Turbinate Bones 237
Twitching 260
Unerupted Teeth,
Brought into Position 165, 418
Malposed 206, 259, 262, 417
Unit 326
Upper Anterior Teeth, Radiography
of 103
Upper Posterior Teeth, Radiog-
raphy of 98
Uses of the Radiograph in Den-
tistry 146 to 273, 416 to 423
Using Coolidge Tube, Technic... 334
Vacuum 41, 42
Regulator 45, 331
X-ray Tube, of 42, 340
Valve Tube 53, 337
Van Woert,
Developing Tank 134
Film Holder and Indicator 350
Technic 134
Velocity of Electricity 3
Velox 83
Ventilation of Dark Room 348
Vibrator 17, 23
View Boxes 136, 406
Villard Tube 54
Volt :...... 3
Washing,
Of Negative .79, 132, 350
Of Print 84
Watt_ 5
Winding,
Primary 11, 12, 27, Zi
Secondary 11, 12, 27, 2i2)
Wiring for Installation 15, Z6
Wires in Canals. 173 to 176, 179, 183, ?,77
Wisdom Teeth (See Third Molars)
X-ray,
As a Therapeutic Agent 294
Burn .273, 274, 290, 425
Carelessness with 426
Dangers of 273
Dental Machines 320
Discovery of 49
Dose of 288, 424
Film 66, 96
Ignorance with 426
Limit of Exposure to 288,424
Machines 14
Outfit 295
Penetration of 56
Proof Box 297, 346
Tubes (See Tubes).
Tube Stand 59, 60, 284,296
Unit .....326
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