Columbia (Bnitiers^itp mtlieCftpotlmigork c»j^. »L College of ^fjpsiitiang anb burgeons; NOTHING is more worthless than an incorrect diagnosis, and no matter how well the wrong treat- ment is applied, it remains the wrong treatment. First of all, then, make a correct diagnosis. H. R. R. ELECTRO-RADIOGRAPHIC DIAGNOSIS Digitized by the Internet Archive in 2010 with funding from Open Knowledge Commons http://www.archive.org/details/electroradiograpOOrape ELECTRO-RADIOGRAPHIC DIAGNOSIS A Book on the Electric Test for Pulp Vitality, Giving the Technic OF Its Use in Detail and Submitting Clinical Evidence of Its Absolute Necessity to Dental Diagnosis BY HOWARD RILEY RAPER, D.D.S. Formerly Professor of Radiodontia, Materia Medica and Operative Technic, and Junior Dean, Indiana Dental College; Author of "Elementary and Dental Eadiography. " WITH 135 ILLUSTRATIONS ST. LOUIS C. V. MOSBY COMPANY 1921 1^ ^ Copyright, 1921, by C. V. Mosby Company (Printed in U. S. A.) Press of C. V. Mosby Compa/iy St. Louis TO MY IDEA^ OF A MOTHEE THAT IS^ TO MY MOTHER PREFACE The object of this little book is to help bring the electric test for pulp vitality into its deserved popularity and the writer hopes to accomplish this by doing two things : (1) By showing how frequently the test is necessary to cor- rect dental diagnosis and (2) by teaching in detail the technic of its application. Every dentist who has an x-ray machine, and every dentist who does not have an x-ray machine, should use the electric test for pulp vitality. In short the electric test is of the utmost value to any one who attempts dental diagnosis. It is often absolutely indispensable to correct diagnosis, of which fact the reader will be convinced, I believe, by reading Chapters X and XI. The writer has had most of the notes used in the writ- ing of this little book in his possession since 1916, at that time, I dare say, there were not fifty dentists in the United States using the test. In the past four years the test has commenced to receive a wider recognition. But even yet only a comparatively few dentists use it. The reasons for this, it seems to me are: First, the value and importance of the test are not fully appreciated. Second, the necessity of acquiring knowledge of correct technic is not appreciated. Third, the dental electrodes in use are inadequate. Let us consider each of the foregoing. First, the value and importance of the test : I believe I am right in saying that, with a few exceptions, the only men to have a really comprehensive idea of the impor- tance of the electric test as a diagnostic measure are a few radiodontists. The electric test for pulp vital- ity is one of those things which, being well known of, is little knoivn about. 10 PREFACE Second, the necessity of acquiring knowledge of correct technic: Dentists seem actually to consider it beneath tlieir dignity to try to learn how to apply the electric test well-. They say, "Why all there is to it is to touch the tooth, and if it hurts it is alive, and if it doesn't it is dead. Isn 't that right ? ' ' I believe it requires more skill and judgment to apply the electric test correctly than to make photographically good radiographs. (Please note that I say "photo- graphically good radiographs." Do not misunderstand me to mean a good radiographic diagnosis.) The present attitude towards the electric test (and the radiograph, too, for that matter) reminds me of the his- tory of amalgam, vulcanized rubber plates, and the inlay. When amalgam was first introduced the curbstone de- scription of the technic for using it ran something like this : ' ' You simply take some filings in your hand, add a few drops of mercury, and rub them together with your thumb. The stuff gets like putty, and you daub it into the cavity." When rubber for plates was discovered it made denture making so easy a halfwit could do it — or did it 1 When the inlay appeared, all. there was to it was to "punch a little soft wax into the cavity, have the patient bite, trim off the excess, pull it out, and dismiss the pa- tient." The next day the patient came back and the inlay was slipped into place (??). Time has caused us to alter our opinion of these things. But we are going right ahead, making the same mistakes about the simplicity of making radiographs and the sim- plicity of applying the electric test for pulp vitality. The truth of the matter is, or so it seems to me, that it is ex- tremely easy to do a thing badly but hardly ever easy to do it well. There are details about the technic of doing most any- thing which must be learned by personal experience. PKEFACE 11 However, the personal experience of another may make your task of developing technic much easier. My per- sonal experience in the application of the electric test has been rather extensive. I have traveled from the point where I considered the use of the test absurdly simple to the point where I know it is not so simple as it looks, at first sight. I hope I blaze the trail and make the going a bit easier for those who read this little mono- graph. Third, the dental electrodes in use are inadequate: It is little wonder that the test is not more popular, and that some men have started to use it, only to discard it. Most of the dental electrodes I have seen in use are such as to render the correct application of the test either ex- tremely difficult or absolutely impossible. In this con- nection I may say that I have never kno^^ai any one, who has taken the time to master the technic, to discontinue the use of the test. Though I find myself in rather extensive disagreement with what he has written, I want to direct attention to the fact that the first man to have even an inkling of the real importance and size of the subject of electro-diagnosis of pulp vitality was Dr. Herman Prinz. Dr. Prinz, years ago, devoted a chapter of several pages to the subject in his book on therapeutics. Upon reading it at the time I recall my tendency to ridicule Dr. Prinz 's efforts and to accuse him, in my mind, of having an inordinate lot to say about a subject, which, as I thought then, should have been covered in a few paragraphs. In making this ad- mission I automatically apologize to Dr. Prinz, and give him credit for his foresight. Now I find myself writing a whole book on the subject! I have tried to make the book as short as possible and still have it cover the subject in a thorough manner. Read it, and see whether you do not come to the same conclusion I have finally reached, wliich is, simply that tJie subject is 12 PREFACE a bigger one than ive gave it credit for being. I direct your attention to the fact that, in order to keep the book as small as possible, I have included no history, neither have I been able on this account — the effort to keep the book small — to include anything even remotely ap- proaching a detailed electrical description of the various types of pulp testing machines. To the beginner, particularly, I would say one should not attempt to ingest, digest, and assimilate the subject at one sitting. Don't study it, just read the book from be- ginning to end. Then commence the work, and study the book by referring to it as you progress with the work. If after starting to use the electric test you are about to discard it, I earnestly advise you not to. Try again, for, like the radiograph, the electric test for pulp vitality is with us to stay. Electro-determination of pulp vitality is as essential to dental diagnosis as airplanes are to modern Avarf are. Even after an author has seen good proofs, and there- fore knows that good halftone plates have been made for his radiographic illustrations, he cannot be sure that the inl?: pictures will appear in his book or his magazine ar- ticle as they appeared in the proof. What the printer will do to one's illustration, as this last step in their mak- ing is taken, is a matter of great uncertainty. I have done more retouching in this work than I have ever done before. Even so, I have not done a great deal. When my first work on Eadiodontia was printed I did not dare do much retouching. My readers would not have accepted my radiographs as true had I done so. Today, however, the profession as a Avhole has become sufficiently familiar with x-ray findings so that an author need not be so careful to protect himself against unjusti- fiable incredulity. PREFACE 13 TJie blacks and whites of ''negative halftone " illustra- tions are the same as in the original negative. The blacks and whites of "print halftone" illustrations are the same as in a photographic .print made from the original neg- ative. Both have their advantages and disadvantages. The "'print halftone" can be made to carry more detail but the "negative halftone" looks better and can be re- touched to better advantage. Of course it is imiDossible to laiow what the future holds. The electric test for pulp vitality has sufficient virtues so that it should become popular, but there are some things that react against it. All of the many de- tails necessary to its really intelligent use are set forth in Chapters V, VI, VII and VIII, for example. But then there is this to be said : Lil^e the amalgam filling and the radiograph, it may be used in a very inadept manner and still some good results will accrue. Men who find dental x-ray diagnosis very easy will not welcome the idea that pulp testing is necessary, for it will make their work harder for them. But men whose ambition it is to make a correct diagnosis even if it does require work will welcome the test. The "Analysis of the Book for the Benefit of the Busy Reader" will, I hope, meet with the approval of "the Busy Reader." The effort is something of an innovation, as far as I know. It is i^rompted by a desire to do unto my reader as I would wish to be done by. I am glad to show my appreciation, by acknowledging my indebtedness and offering my formal thanks to Mrs. H. R. R., who has done most of the literary work (includ- ing the exasperating task of proof reading) which lies be- tween the first "dirty copy" and the finished book. H. R. R. Albuquerque and IndiaiiaxJolis. CONTENTS Chapter I By Way of a Beginning 19 Chaptee II Pulp Testing Machines 23 Chapter III Eequisites of a Pulp Testing Outfit 35 Chapter IV Funcfamentals in Teclinic of Apx^lying Electric Test 45 CilAPTER V Special Points in Technie 50 Chapter VI Things Which Modify the Strength of Current Necessary to Test Teeth 75 Chapter VII Limitations 83 Chapter VIII Applying the Test for Nervous Patients 86 Chapter IX Answering Adverse Criticism 91 Chapter X Clinical Value of the Test 95 Chapter XI The Test as an Aid in the Interpretation of Eadiographs 108 14 ILLUSTRATIONS FIG. PAGE 1. Unsightly Faradic outfit 25 2. Neat appearing Faradic machine 27 3. A very elaborate and expensive type of galvanic and Faradic machine 27 4. A modified Faradic machine 28 5. An ionization machine (on dental bracket) 30 6. Pulp tester of the type which operates from a lamp socket ... 31 7. High-frequency machine 32 8. Tip or plug 35 9. Showing how some tips separate so a broken cord may be re- paired 35 10, 11, and 12. Wrong types of dental electrodes 37 33. A combination current controller and dental electrode 38 14. The right kind of dental electrode 39 15. The common type of hand electrode 40 16. Hand electrode of special design 40 17. A type of indifferent electrode which clamps on the cheek ... 40 18. Cotton holder with ring of blotting paper about base 41 19. Small medicine dish 41 20. Dental mouth mirror 41 21. Dental cotton tweezers 41 22. Eecord blank to record results of the applications of the electric test for pulp vitality 43 23. Special Faradic type pulp tester with parts labeled 46 24. Moisture contact, not actual contact 51^ 25. How cotton should be wrapped on the dental "electrode .... 53 26. Wrong way to wrap the dental electrode with cotton 53 27. Touching tooth with the end of the electrode 55 28. Electrode laid against surface of tooth 56 29. Showing where and why cords wear out and break 60 SO. Applying the electrode to the labial surface of an upper anterior tooth 63 31. Applying the electrode to the lingual surface of an upper anterior tooth 64 32. Applying the electrode to the buccal surface of an upper left pos- terior tooth ^^ 33. Applying the electrode to the lingual surface of an upper left pos- terior tooth ^^ 15 16 ILLUSTRATIONS riG. PAGE 34. Applying the electrode to the buccal surface of an upper right posterior tooth 67 35. Applying the electrode to the lingual surface of an upper right posterior tooth 68 36. Applying the electrode to the labial surface of a lower anterior tooth 69 37. Applying the electrode to the lingual surface of a lower anterior tooth 70 38. Applying the electrode to the buccal surface of a lower left pos- terior tooth 71 39. Applying the electrode to the lingual surface of a lower left pos- terior tooth 72 40. Applying the electrode to the buccal surface of a lower right pos- terior tooth 73 41. Applying the electrode to the lingual surface of a lower right pos- terior tooth 74 42. In some cases it may be expedient to make an opening through the enamel to apply the dental electrode 77 43-135. Eadiographs 109-153 ANALYSIS OF THE BOOK FOR THE BENEFIT OF THE BUSY READER CHAPTER I By Way of a Beginning A short chapter in which the writer sets forth some of his views regard- ing the electric test for pulp vitality. Of passing interest. CHAPTER II Pulp Testing Macpiines In which tlie various types of pulp testing machines are mentioned and their relative advantages and disadvantages discussed. Not much said about electric construction. CHAPTER III Requisites of a Pulp Testing Outfit In which the requisites of a pulp testing outfit are enumerated and discussed. Special emphasis being laid on the necessity of using the right land of a dental electrode. CHAPTER IV Fundamentals in the Technic of Applying The Electric Test foe Pulp Vitality Only the barest fundamentals in the technic of applying the electric test for pulp vitality are set forth in this chapter. The operator must have the knowledge set fortli in this chapter or he cannot apply the test at all. CHAPTER V Special Points in Technic Wherein special points iu technic are described. This is a very impor- tant chapter. The operator need have only the information set forth in Chapter IV to apply the test, but if he would apply it well, he must master the special points in technic set forth in this chapter. CHAPTER VI Things Which Modify the Strength of Current Necessary to Test Teeth Like Chapter V, this is an important chapter. Tlie information it gives is necessary to an intelligent use of the test. 17 18 ANALYSIS OF BOOK CHAP TEE VII Limitations of the Test All tests, no matter how good, have limitations, and it is as necessary to know the limitations of a test as well as the possibilities, and so guard against disappointment and error. CHAP TEE VIII Applying the Test for Nervous Patients A sort of verbal clinic in which the writer attempts to describe in detail how he handles nervous patients. CHAPTEE IX Answering Adverse Criticism Not a great deal has been written about the electric test for pulp vitality but that which has appeared seems to have been either definitely laudatory or definitely derogatory. The writer has already discussed the limitations of the test and here answers criticisms which seem to him unjust. CHAPTEE X Clinical Value of the Test A chapter to be browsed over. An effort to indicate the clinical value of the test verbally. CHAPTEE XI The Test As An Aid in the Interpretation of Eadiographs (Cases from Practice) An effort to prove the value of the test by submitting considerable radiographic evidence of its necessity to the correct interpretation of radio- graphs. Perhaps the most important chapter in the book. ELECTRO -RADIOGRAPHIC DIAGNOSIS CHAPTER I BY WAY OF A BEGINNING There is no incentive to study the always more or less dull subject of technic unless one is aware of the benefits to be derived. So, my reader, if you are not already cog- nizant of the importance of the electric test for pulp vitality as a diagnostic measure, perhaps you should read the last two chapters first. It may give you more enthusiasm for the task of mastering technic. And re- member, results depend on technic; poor technic, xDoor results. Why We Test Teeth for Pulp Vitality It is so nearly correct that it is ciuibbling to dispute the statement that a tooth with a vital pulp is never ab- scessed — i. e., never a source of periapical infection — Avhile the tooth without a vital pulp may be abscessed. Hence the necessity in the practice of dentistry and radio- dontia of determining pul^D vitality. I have never encountered a case of periapical abscess of a tooth with a vital pulp.* Those cases which have been brought to my attention by others have all seemed to me to be mistakes in diagnosis. For example, a man shows me a radiograph in which two ai^proximating teeth seem to be involved in an ab- scess and says, "One of those teeth had a vital pulp. There's a case of abscess at the ajoex of a vital tooth." *I am not considering here multirooted teeth with the pulp in one canal dead and septic and an abscess at the apex of the root while the pulp in another canal remains vital or semi-vital. 19 20 ELECTRO-KADIOGRAPHIC DIAGNOSIS His clisagreeiiient and mine arises from the fact that he accepts what the radiograph seems to show without ques- tion, without taking into account the fact that the angle at which the radiograph was made may have been such as to cause an overlapping of a root end and an abscess cavity which have no actual connection with one another, or that the abscess cavity may lap to the lingual of the tooth with the vital pulp without involving its apex. It is a homely comparison but it expresses my view of the matter to say that a hose or rope cannot pass through a bonfire without being burned in two. Neither can blood vessels and nerves pass through an abscess to enter a tooth without being '^ burned" in two. Electric Test Compared to Other Tests No test for pulp vitality, other than that of making a diagnostic opening into the tooth, is infallible — not even the electric test. But the electric test is so far superior to all others that it should be, and is coming to be, used by all dentists and dental radiographers. Carried to its logical conclusion — to the point of sensitivity or into the pulp cavity — the procedure of making a diagnostic open- ning into a tooth is absolutely reliable as a means of de- termining pulp vitality. But this procedure of opening the tooth is the very thing we wish to avoid if possible. To avoid the necessity of opening teeth to determine pulp vitality, thermal tests, transillumination tests, and palpation tests are as inadequate, when compared to the electric test, as the old hand excavating instruments com- pared to the modern dental engine. ''Too Rosy" While the writer fully appreciates the merits of the electric test for pulp vitality and counts the test a neces- sity for dentists and radiodontists, it would seem wise, however, to give a word of warning. BY WAY OF A BEGHSTNING 21 Enthusiasts say tilings like this about the test: ''Abso- lutely painless," ''Absolutely reliable," "So simple the technic of its use can be mastered in a few moments," "Enables the operator to locate devitalized teeth speed- ily and without fail, " "If you fail to get a reaction from this test it is quite certain the pulp is devitalized." There is good foundation for such remarks as tlije fore- going, and yet they are very misleading; they are too rosy. They lead men to expect too much. "Absolutely reliable " is a very dangerous thing to say about any test. Pulp Devitalization Due to Application of the Test Just having remarked on the care one should exercise when using that very uncompromising word ' ' absolutely" the writer feels he is exercising necessary care and is justified in using it and saying that, so far as danger of devitalization of the ]Dulp is concerned, the test is ab- solutely safe. As I make this statement I have in mind the use of the Faradic type of pulp testing machine. Per- haps the other types are just as safe, but I do not kiioiv it to be a fact from experience as I know of the safety of the Faradic machine. Advantages of the Test The advantages derived from using the electric test for pulp vitality, in connection with radiographic exam- ination, are: (1) Misinterpretation of radiographs is much less likeh^ to occur. (2) The application of the test enables the operator to select those teeth which should be radiographed with especial care. (3) Because it assists in radiographic interpretation and because it points out the particularly suspicious teeth, the test reduces the number of exposures necessary, particularly the number of make-overs necessary. (This is especially advanta- geous to the conscientious operator.) (4) When, in a case 22 ELECTRO -RADIOGRAPHIC DIAGNOSIS of metastatic infection the patient cannot afford to have all parts of the month radiographed, the number of radio- graphs made, and so the cost, can be reduced to a mini- mum by eliminating those teeth from examination which respond perfectly to the electric test for pulp vitality. (5) Carelessly used, x-rays are dangerous. An x-ray tube should never be lighted unnecessarily. Th'fe use of the test lessens exposure of both patient and operator. CHAPTER II PULP TESTING MACHINES The Source of the Current To apply the electric test for pulp vitality we must have an electric current of the proper nature, i.e., a current of the correct voltage, amperage and character. The or- dinary commercial current, as supplied, cannot be used. The commercial current may be passed through an elec- tric machine and modified to meet the requisites of a current suitable for testing pulps for vitality. Likewise the current of a drj^ cell may be passed through an electric machine and so modified to conform to the requisites of a current suitable for testing pulps. Types of Pulp Testing Machines The following are types of machines used as pulp test- ers, named somewhat in the order of their popularity. The first and last ones named derive their current from dry cells (batteries) while the others operate on the com- mercial circuit. (1) The Faradic machine. (2) The ion- ization machine. (3) The dental switchboard. (4) The choke coil or rheostat, or transformer. (5) The high- frequency machine. (Also known as the Tesla coil and "violet ray machine.") (6) A flashlight battery ma- chine. The Faradic Machine As its place in the list of pulp testing machines indi- cates, the most extensively-used type of pulp tester is the Faradic machine. Ever^'-thing considered, i.e., safety, 23 24 ELECTRO-EADIOGRAPHIC DIAGNOSIS transportability, ease in handling, comparatively low cost, and high efficiency — its popularity is entirely mer- ited. The Parts of a Faradic Machine The essential parts of a Faradic machine are: a dry cell, an interrupter, and a coil. Tracing the Current Through the Machine From the cell the current passes through a mechanical interrupter (Fig. 2) and thence to a little step-up tran^*- f ormer or coil, by means of which the current of compar- atively high amperage (quantity) and low voltage (pres- sure), from the cell, is transformed into a current of comparatively low" amperage (quantity) and high voltage (pressure). It is also changed from a direct current to an alternating current. Safety A machine which generates its own current, so to speak, like the Faradic machine, has some advantages over any switchboard attachment or any machine deriving its elec- tricity from some powerful source of supply. In case of accident or misuse no serious results can occur, for the perfectly apparent reason that the current generated from one commercial dry cell cannot be strong enough to be dangerous. This should appeal to any one, but par- ticularly to men whose knowledge of electricity is limited. The manufacturer of a pulp testing machine which operates by connection to a light socket directs attention to the humming noise produced by the Faradic machine and claims the noise may frighten patients. If one would be just, it is necessary to concede the fairness of the criticism. However, which, may I ask, is more likely to PULP TESTIISTG MACHINES 25 frighten the patient, tlie hnm of the Faradic machine or the sight of an electric machine, one end of which is at- tached to a light socket and the other end about to be introduced into the patient 's mouth f To carry the picture still further the operator, having a machine attached to a lamp socket, now moves the pa- ■Unsiglitly Faradic outfit. tient's arm from where it touches the metal trimming of the fountain cuspidor with the solenm warning, "You mustn't be in contact with any metal when I apply this test." Does the patient now feel perfectly secure? AVhen the Faradic machine is used, contact with metal cannot possibly result in any accident. 26 ELECTKO-RADIOGRAPHIC DIAGl^TOSIS Transportability The machine that generates its own current from a commercial dry cell depends only on the cell and, with the cell supplied, will operate any time, anywhere, and with- out variation. It can be moved from place to place in the office, or from place to place anywhere on the face of the earth for that matter. The absence of a cord, con- nected to a light socket, which is everlastingly upsetting something or other on one's bracket or cabinet, increases the comfort with which one moves the machine in the position for use, then out of the way again. The ordinary dry cell can be obtained anywhere in the civilized world. A cell will give service for about one year, when it may be replaced very easily at a small cost. The Appearance of Faradic Machines Commercial Faradic machines, as found on the market, vary greatly in appearance. Some are unsightly and awkward to handle, especially those in which the cell and coil are not mounted together, but are separate with only wire connections. (Fig. 1.) Others are ordinary look- ing. Some are rather attractive. (Fig. 2.) Still others are very elaborate in appearance. (Fig. 3.) Most of them may be recognized by the patient as what is collo- quially designated a "shocking machine." This is a dis- advantage, for when it is recognized as a shocking ma- chine, some patients are more reluctant to submit to its use. Perhaps they remember its sting, or perhaps it is be- cause they do not appreciate, or may even hold in con- tempt, anything which is familiar to them. An Effort and a Failure Though the Faradic machine makes a good pulp tester, it is not with^t its shortcomings. Some years ago, in 1917, to be exact, I endeavored to produce a pulp testing PULP TESTING MACHHsTES 27 machine of the Faradic type which would have the fol- lowing improvements over the ordinary commercial Faradic machine: (1) It was to have the right kind of a INTERRUPTER COIL -V-. SLIDING SHEATH Fig. 2. — Neat appearing Faradic machine. Fig. 3. — A very elaborate and expensive type of galvanic and Faradic machine. dental electrode. (2) It Avas to he a neater, better looking outfit. (3) It was to have an appearance that would not remind the patient of the familiar "^shocking machine." 28 ELECTRO-EADIOGEAPHIC DIAGJSTOSIS (4) It was to have a better control of the output current. (5) It was to make less noise. (6) It was to cost only a little more than the ordinary Faradic machine. After much trouble the machine shown in Fig. 4 was produced. Of the six objectives just given, only the first three were attained. The dental electrode was all one could desire ; the outfit was really attractive ; and it in no way resembled the old ' ' shocking machine. ' ' There was no improvement whatever in the control of the output current over the controls on the ordinary Faradic ma- Fig. 4. — A modified Faradic machine. chine; it made more, instead of less, noise, and, owing to the increased cost of everything due to the war, its selling price was high. As though this were not enough, the machine harbored a serious, inexcusable mechanical de- fect. As soon as I directed attention to the serious faults of the pulp tester, it was promx^tl}^ withdrawn from the market. A Defect of Faradic Machines and How to Overcome It Ionization machines and the expensive pulp testing machines which operate from lamp sockets, have a single PULP TESTIXG MACHINES 29 current controller wliicli grades the output current from zero, or approximately zero, to the maximum strengtli needed, while the output current of the ordinary com- mercial Faradic machine is regulated in two ways: One, by the manner of attaching the electrodes to the machine, the other by a cylinder controller, i.e., the sliding sheath or tube, which increases the current strength as it is pulled out. (Fig. 2.) To cope with this shortcoming of having to change plugs, I have developed a stratagem or '^ stunt" in technic, (see Chapter V under the heading "A Valuable Point in Technic") which meets the situa- tion and overcomes its difficulties, on most machines. It must be admitted, however, that there are some Faradic machines which are controlled so imjDerfectly by their sliding sheaths that they are not amenable to any stratagem and so make poor pulp testers. I should make it clear that it is not the fact that there are two modes of control which are especially objectionable, but the objection is to the nature of one of the controls ; that is, the objection is to the necessity of changing un- insulated plugs from one socket into another. However, one cannot gainsay the fact, it is easier to operate a machine which operates from a single control and grades from zero or ajoproximate zero upward. Some of the more expensive Faradic machines are equipped Avith '^ choke coils" or rheostats instead of the sliding sheath. Such machines admit of a more perfect control of the output current. Another Effort Though I failed so utterly in my first effort to have an ideal pulp tester made of a Faradic machine, the failure was due entirel^^ to preventable mistakes and such an ideal pulp tester, I am promised, is now being produced bv another manufacturer. 30 • ELECTRO-EADIOGRAPHIC DIAGNOSIS The Ionization Machine Equipped with the right kind of a dental electrode (Fig. 14) some ionization machines (Fig. 5) make ade- quate pulp testing machines. An ionization machine should not be purchased if it is to be used only as a pulp testing machine, for a good pulp testing machine of a different style, say the Faradic type, can be purchased Fig. 5. — An ionization machine (on dental bracket). at much less expense. If, however, one intends to use, or is using ionization, then the ionization machine may be used as a pulp tester if the current it generates is strong enough. The Dental Switchboard Some dental switchboards are, I understand, now made with sockets (places for attachment) where a suitable current for pulp testing may be obtained. If the switch- PULP TESTIXG IMACHIXES 31 board lias been built witli the idea of giving tlie operator a pulp testing current, doubtless such a current is avail- able, for dentistr^^ is fortunate in having such reliable manufacturers of electric equipment. But certainly it is "risky business" to "tap" somewhere into a switch- board, not built especially to deliver a pulp testing or ionization current in the hoioe that the current attained will be of the right character. As always, when using the dental switchboard as a pulp tester, one must use the right kind of dental elec- trode, or failure will result no matter how joerfect the current supplied may be. The Choke Coil, Rheostat or Transformer The machine I designate as a choke coil, rheostat, or transformer (Fig. 6) operates from a lamjD socket. As the name implies, the commercial current taken from the light socket is choked back or altered by means of a transformer coil and delivered by the machine for use in the correct strength to test pulps. Fig. 6. — Pulp tester of the type which operates from a lamp socket. The necessity of connecting this little machine to a light socket is disadvantageous and sometimes amioying. However, these things are not vital to the efficiency of the machine as an adequate iDulp tester. 32 ELECTEO-EADIOGRAPHIC DIAGNOSIS The High- Frequency Machine (Also known as the Tesla Coil and Violet Ray Machine) The high-frequency machine (Fig. 7) is used by some as a pulj) tester. Perhaps the best wa,y to express its status as a pulp tester is to say it has undeveloped possi- bilities. The fact that the high-frequency current may be applied to metal fillings and crowns without extreme pain is an advantage but the following shortcomings are serious disadvantages: (1) Ordinary insulation does not suffice; the current penetrates heavy wire insulation. Fig. 7. — High-frequenc}' machine. Also known as Tesla Coil and "Violet Ray Machine." Therefore, the wire, or cord, must not be allowed to come in contact with the patient. The patient's clothing offers no protection to a current of such an extreme penetration. The current is not dangerous but it is disagreeable, and frightens patients. (2) The dental electrodes are big and awkward to handle — entirely impractical in my opinion. (3) The machine makes a distracting racket. (4) Al- though a small quantity of the current sparked into the metal of a filling or a crown does not cause pain, a large enough quantity will cause a pain reaction even if the PULP TESTING MACHINES oo tooth is not vital. (5) Tlie means of regulating the high- frequency current is neither very accurate nor easy. Dr. Simpson's Opinion I must admit that I have never used the high-frequency current except experimentally. That is I have never used it in routine practice. Dr. Clarence 0. Simpson has used the high-frequency current for pulp testing for two years and so let us see what he has to say about it. I am in- debted to Dr. Simpson for the statement Avhicli follows : "Regarding the use of the high-frequency current for vitality test, let me preface the statement by admitting that it is not automatic, showing a plus or minus on an indicator when a tooth is touched, but some experience, imagination, and discrimination must be employed. There is a great difference in the response from different patients, but vitality can be determined in most cases ex- cepting those of extreme pulp recession and crowned teeth. When a very strong current is used on a crown or pulpless tooth, it jumiDS to adjacent teeth with that possibility of error, but most teeth respond before the current is raised to that degree. This difficulty does not arise excepting in lower incisors or pulp recession. In- sulation by rubber dam reduces the jumping, but only to a limited degree, isolation is more accurate than insula- tion since high-frequency current baffles all practicable insulation media. Some of the advantages of high-fre- quency for pulp testing are: A greater capacity than can be obtained from the usual faradic generators, the ab- sence of shock to the tongue and on metallic restorations, and obviation of the necessity of the patient 's holding an electrode. ' ' The Flashlight Machine Everyone has seen pocket electric flashlights of all kinds: some almost as small as a fountain pen, others much larger and giving a stronger light. 34 ELECTRO-RADIOGRAPHIC DIAGNOSIS The flash light battery pulp tester is at the present time little more than an idea in the mind of one of my friends. If I am to believe what I am told (I have never seen it) an experimental machine of this type has been made and ' ' works fairly well. ' ' The principle of such a machine does not appeal to me. The most important single thing about a pulp testing out- fit is that the dental electrode shall be right, shall be neat and easy to handle. The feature of the flash light battery pulp tester is that it shall be so small a machine that it may be handled in one hand and used as a dental elec- trode. Such a machine, as a machine, may be small and neat, but as a dental electrode, it is too big and awkward to handle. For this reason, if no other, I have no enthu- siasm for it. CHAPTEE III REQUISITES OF A PULP TESTING OUTFIT A pulp testing outfit sliould consist of pulp testing ma- chine, cords, dental electrode, hand electrode, cotton holder, cotton, piece of blotting paper or napkin, vessel to contain water or saline solution, mouth mirror, cotton tweezers, blanks on which to keep records. Pulp testing machines have already been considered in Chapter 11. Cords The cords or insulated wires which are used to connect the electrodes to the machine should be of sufficient length. Fig. 9. — Showing how some tips separate so a broken cord may be repaired. If the tips or plugs (Fig. 8) on the ends of the cords are insulated instead of the usual metal tip, it is advan- tageous. When such insulated tips are used, they may be changed from one socket to another while the machine is turned on without danger of shocking the operator or patient. (The metal tip may be covered with adhesive tape to insulate if desired.) Cords not infrequently break just where they enter the tip or plug. Some cord tijDS are so made that this break may be repaired easily. (Fig. 9.) 35 36 ELECTEO-EADIOGEAPHIC DIAGNOSIS - The Active or Dental Electrode The use of inadequate dental electrodes has done more to discourage beginners and keep operators from realiz- ing the full benefits to be gained from the test than any other thing. Take Figs. 10, 11, and 12 as examples of the wrong kinds of dental electrodes. When using them the oper- ator is constantly coming in contact with the uninsulated parts at the base of the electrode; and the patient's lips, cheeks and tongue are touching the uninsulated parts at the other end of the electrode. When the operator's hand touches the uninsulated parts, he receives a shock and if his other — his left — hand is in contact with the patient as it usually is, resting against the patient's face (the fingers holding a mouth mirror perhaps, and the mirror in the patient's mouth) the shock is transmitted to the patient. Fig. 13 is a combination dental electrode and current controller. The current strength is increased by pushing in a piston very much as one pushes in the piston of a syringe. This sort of electrode is an awkward thing to handle, a fatal fault. The hand which seeks to direct a dental electrode to touch teeth at the right spot without touching lips, cheeks, tongue, or gum, or mouth mirror, is a busy hand; it should not be called upon to regulate the current also. Since the application of the electric test has come to occupy such an important place in the writer's radio- dontic practice, all sorts of dental electrodes have been tried. At one time a set of three different electrodes were used to reach the various surfaces of the teeth without touching the soft parts. Finally the electrode shown in Fig. 14 was designed. It is almost absurdly simple, yet it seems to be precisely the right thing for the use to which it is put. Those who have used other dental elec- trodes or sets of electrodes like those shown in Figs. 10, 11, and 12, for example, w^ll share my enthusiasm for this very simple but very adequate little instrument. REQUISITES OF A PULP TESTIjSTG OUTFIT 37 The working end, i.e., the uninsnlated metal part, of the electrode (Fig. 14) should be bent at an angle of about 45 degrees to the long axis of the instrument. Different TA -UM. UM/ Fig. 10. Fig. 11. Fig. 12. Figs. 10, 11 and 12. — Wrong types of dental electrodes. Too much exposed (i.e., uninsulated) metal, and the wrong shapes. UM., Uninsulated metal. 38 ELECTEO-KADIOGRAPHIC DIAGNOSIS operators may wish to vary this angle slightly. This may be done with a pair of pliers without injury to the in- strument. The Indifferent or Hand Electrode The type of hand (also called indifferent or neutral) electrode illustrated in Fig. 15 is familiar to almost every- body. Fig. 16 shows a camouflaged type of hand electrode. The sight of it does not remind the patient of childhood experiences with a ''shocking machine," for such an elec- trode is not ordinarily used with a Faradic machine. Fig. 13. — A combination current controller and dental electrode. Impractical, in the writer's opinion. Instead of a hand electrode, there is a type of indiffer- ent electrode which clamps on the cheek, one side inside the mouth, the other outside, which may be used, or a sponge may be strapped to the Avrist, or a sponge on a wooden handle may be used, the patient having the wooden handle in one hand and pressing the sponge against the other hand, or the arm. The cheek electrode (Fig. 17) is not a good one to use when applying the electric test for pulp vitality, espe- cially when all or manj^ of the teeth are to be tested ; it is in the ivay. The wrist electrode strapped to the wrist serves the purpose of an indifferent electrode nicely except that the psychic effect of strapping the electrode fast is not good with some patients. An advantage in strapping an elec- EEQUISITES OF A PULP TESTING OUTFIT 39 trode in place is that it is held against the tissues at uni- form pressure. Instead of strapping it to the wrist, this electrode may be held in the hand, like a hand electrode, if desired. urn Fig. 14. — The riglit kind of dental electrode. Simple, efficient, insulated save at extreme working- end. Will reach all parts of all teeth without some metal part coming in contact with the patient's cheeks, lips or tongue or operator's hands. 40 ELECTRO-RADIOGRAPHIC DIAGNOSIS The sponge on a handle is an adequate electrode and serves to keep the patient somewhat occupied, a good thing from a pyschic standpoint. However, this objec- Fig. IS. — The common type of hand electrode. (This electrode is also called the "indifferent" and the "neutral" electrode.) Fig. 16. — Hand electrode of special design. Fig. 17. — A type of indifferent electrode which clamps on the cheek. Impractical for pulp testing, because in the way. tion might be raised to the nse of a sponge electrode. Care must be taken to keep the sponge moist; Avhen dry it ceases to be a conductor of electricity. REQUISITES OF A PULP TESTING OUTFIT 41 Cotton Holder, Cotton and Blotting- Paper or Napkin Absorbent cotton is needed to wrap about tlie point of the dental electrode and, on occasion, to put nnder the tongue and in the vestibule of the mouth to keep the parts dry while the test is applied. Dentists all have cotton holders. Physician radio- graphers, however, who do dental radiographic work and use the electric test to check their radiographic findings will find themselves in need of some sort of holder for cotton. Fig. 18 shows a cotton holder designed by the writer. The feature of this holder is that a ring of blotting paper Fig. IS. Fig. 19. Fig. 20. Fig. 21. Fig. IS. — Cotton holder with ring of blotting paper about base. Fig. 19.— Small medicine dish. Fig. 20. — Dental mouth mirror. Fig. 21. — Dental cotton tweezers. fits over the dome of the holder and rests on the base. Those who do not wish to invest in a manufactured cotton holder may make one by cutting a hole in the tin top of a glass salve box. When the dental electrode is dipped into water or a salt solution, to moisten it, it comes out dripping wet. To take up this excess moisture it is pressed against blotting- paper or a clean napkin. 42 ELECTEO-EADIOGRAPHIC DIAGNOSIS For use under the tongii,e and in the vestibule of the mouth, Johnson and Johnson's prepared cotton rolls will be desired by some in preference to loose cotton made into a roll by the operator. Small Medicine Dish Fig. 19 shows a small medicine dish, for the water or saline solution used to moisten the cotton on the dental electrode. Any sort of a container will do for the pur- pose, of course. The writer suggests the one illustrated only because it is neat in appearance and cheap. Dental Mouth Mirror A dental mouth mirror, or similar instrument, is neces- sary to assist the operator in keeping the tongue and cheeks out of the way while the electrode is applied to the teeth. It is also used to reflect light into dark parts and to "work to the image," An instrument like a mouth mirror, but made of some nonconductor, would be better than a metal mouth mir- ror; no unpleasant shock would occur then if the end of the dental electrode happened, by accident, to touch it. Dental Cotton Tweezers All dentists, of course, have such tweezers. Their use in connection with pulp testing is to carry cotton rolls under the tongue and into the vestibules of the mouth, and to hold cotton to wipe off the moisture covering teeth. Record Blanks It does little good to test teeth with the electric test unless careful records are kept of the results. In my practice of radiodontia, as a specialty, it is my routine practice to use the test in practically all cases. With few exceptions, my procedure is as follows : First, the test is REQUISITES OF A PULP TESTING OUTFIT 43 applied and records made. Then the exposures for the radiographs are made. When the negatives are devel- oped they are examined hastily while still wet. At this point some negatives may be made over and some teeth re-tested, depending on the particular case and the find- ings. The patient is now dismissed. Then, later, with the radiographs mounted and the electric test records and other records of the case before me, a "report" — i.e., a diagnosis, prognosis, etc., — is dictated or written and += Responds to elec- tric test for pulp vital- ity. + S=Re8pond9 to elec- tric test strong. -t VS— Responds to elec- tric tests very strong. + VW= Responds to electric test very weak. -I-?— Responds to elec- tric tedlv)ut Question if this indicates vital pulp. — ?=Doe8 not respond to'electric test but ques- tion if this indicates pulpless tooth. CT=Cannot test. 0= Crown. M=Ul8Bin£. R=Root or Roots. Remarks; Treatment and subsequent history: over. Fig. 22. — Record blank used by the writer to record results of the applications of the electric test for pulp vitality. sent, with the negatives, to the practitioner who referred the case for examination. Fig. 22 shows the record blank used to record results of the application of the electric test for pulp vitality. While the vast majority of teeth may be marked simply positive (+) or negative (-), it will be seen from the rec- ord sheet that, so far as this writer is concerned at least, it is not always a simple matter of marking each tooth plus or minus. The results of the application of the test are not always definite enough to justify this. It is fre- 44 ELECTRO-EADIOGRAPHIC DIAGISTOSIS quently necessary to reserve judgment until both the radiographic negative and the tabulated results of the application of the test can be studied. From the record sheet it Avill be seen that a tooth may be marked in any one of eight ways: (1) Positive, (2) Negative, (3) Positive Strong, (4) Positive Very Strong, (5) Positive Weak, (6) Positive Very Weak, (7) Positive Questionable, (8) Negative Questionable. I use still an- other marking, i.e.. Positive Little Weak (+L. W.). Just how each operator will mark his chart will per- haps be a matter for personal decision, but I feel safe in saying that no operator with even a moderate degree of skill in the use of the test will find the two marks (nega- tive and positive) sufficient. CHAPTER IV FUNDAMENTALS IN TECHNIC OF APPLYING ELECTEIC TEST It will be obvious that the description, given here, of the technic of the application of the electric test is given with the Faradic type of pulp tester in mind. However, the principles of the technic set forth are similar no mat- ter what type of machine is used. Note the following in Fig. 23: (1) Main switch. (2) The interrupter. (3) The current controller, i.e., the sliding tube or sheath (Fig. 2), or rheostat Fig. 3. (4) The hand, or indifferent, electrode. (5) The dental, or active, electrode. (6) The little sockets where the elec- trode cords are connected to the machine. There are usually three places or sockets into which the cords may be plugged. From left to right these sockets may be designated either by a letter or a number thus: L. M. r! or 1, 2, 3. Fig. 2 shows the three "sockets" or binding posts. With the cords plugged into 1 (L) and 2 (M) the out- put current, is weakest. With the cords plugged into 1 (L) and 3 (R) the output current is strongest. With the cords plugged into 2 (M) and 3 (R) an intermediate cur- rent strength is attained. It makes practically no difference about polarity. Either electrode may be attached to any socket. When using a machine Avitli the three sockets, the writer uses the connection 1 (L) to 3 (R) only for all cases to avoid the necessity of changing uninsulated plugs. (See Chapter V under the heading ''A Valuable Point in Technic") 45 46 ELECTKO-EADIOGEAPHIC DIAGNOSIS Speaking of the control of the output current of the ordinary commercial Faradic machines with the three sockets, one may say that, like automobiles, they have three speeds or strengths: First or low 1-2 (L-M) Second or intermediate 2-3 (M-K) Third or high 1-3 (L-E) Continuing the analogy, the current controller is now the throttle. INTERRUPTER r^. CURREMT CONTROLLER ^l^ELECTRODE DENTAL ELECTRODE Fig. 23. From here on the steps in technic will be numbered consecutively. . First: Plug the cords, to which the hand and dental electrodes are attached, into the machine. Second : Wrap the metal point of the dental electrode with cotton. Third : Moisten the cotton in water or a sodium chlo- rid solution. TECHNIC OF ELECTEIC TEST 47 Fourth : Expel the extreme excess moisture by touching lightly to blotting paper or napkin. Fifth : Have loatient hold the hand electrode. Sixth: Turn on the current at the main switch. If this does not cause a humming noise, fap the machine or the interrupter sharply. If this does not start the hum- ming, adjust the interrupter screiv. Seventh: "With the current controller set to give the minimum current, touch the tooth to he tested ivith the dental electrode. (When the sliding tube is the form of current controller, start with the tube, or sheath or cylin- der, all the way in, and pull it out to increase the current. When all the way out, the maximum current is deliv- ered.) Eighth: Advance the current controller (i.e., pull out the sliding sheath or advance rheostat) gradually, as necessary to get sensation, proceeding in this manner: Increase the strength of the current a little; touch the tooth with the dental electrode. If there is no sensation, increase the strength of the current a little more ; touch the tooth with the dental electrode again and so on, until sensation is produced or the capacity of the machine has been reached. The sensation will occur in the tooth only — not in the hand — provided the pulp is vital. If the pulp is not vital there will be no sensation with the machine oper- ating at capacity, i.e., with the current controller at maxi- mum. It is not necessary to start Avitli the current controller at minimum for all the different teeth in the same mouth. It will be found that the different teeth resjDond at ap- proximately the same current strength — the "irritation point"- — and the current controller may be left set ac- cordingly and advanced only when necessary to produce sensation. However, better start at minimum if the teeth give promise of being especially susceptible. The lower 48 ELECTEO-RADIOGEAPHIC DIAGiSTOSIS teetli and teetli Avitli the enamel worn off exposing the dentin are usually quite sensitive. (See Chapter W for further discussion of this subject of the amount of current needed.) Tracing the Current The circuit, or course, or path of the current, when the Faradic or galvanic electric test is applied, is as follows : from the machine, through the dental electrode, into the patient's tooth, through the patient, out of the patient through the hand electrode back to the machine. Or the current may follow the same path but travel in the oppo- site direction; the test can be made with the current passing in either direction. The circuit is entirely different when the electrode in Fig. 13 is used. The current passes from the machine through the electrode into the tooth, through the patient, out of the patient into the operator's left hand (which, of course, must be in contact with the iDatient) through the operator, back to the electrode held in the right hand and so to the machine, thus completing the circuit. Perhaps I can make the foregoing clearer if I say that when an electrode like that shown in Fig. 13 is used, the operator's left hand becomes. the indifferent electrode, the operator's body the conducting cord, and the right hand forms the attachment or plug into the machine. Not having to use an indifferent electrode is, in itself, an advantage but this type of electrode has other and serious disadvantages. "\^Tien a high-frequency machine is used, no circuit is needed. The current is so high in voltage, i.e., pressure, it jumps into the tooth, as a spark, when the electrode is even brought close to the tooth before it touches. This occurs Avithout any other electrical connection between the patient and the machine, and without the patient TECHNIC OF ELECTRIC TEST 49 touching a ground to induce tlie current to enter and pass through the body. A ground may be defined as any elec- trical path, like a gas or water pipe, for example, or a wet floor which theoretically, at least, leads eventually to the earth. CHAPTER V SPECIAL POINTS IN TECHNIC A Valuable Point in Technic As stated in Chapter IV, when the machine nsed has three sockets (Figs. 2 and 4), the electrode cords are plugged into ''L-R," i.e., 1 and 3. It is awkward and im- practical to keep changing comiections (by means of un- insulated plugs especially) when a number of teeth are to be tested. However, with the cords plugged into L-R and the current controller at minimum — particularly when the cell in the tester is new — the machine may be found to deliver a current slightly stronger than desirable for some cases* In this event, do not actually touch the teeth with the dental electrode. Make the cotton on the dental electrode quite moist, and place it close to the tooth being tested until the water from the moist elec- trode is seen to touch the tooth and so establish an elec- tric connection (Fig. 24). The amount of current i^assing into the tooth will vary somewhat according to the per- fection of the electric connection or contact of the dental electrode with the tooth, and the water connection is ob- viously not as perfect as though the cotton were placed in actual contact with the enamel. This procedure of making the "moisture contact" will also help the operator very much in cases of extremely nervous patients who always flinch in anticipation of pain whenever they feel the electrode touch the tooth, for the electrode does not touch the tooth and the patient does not know when the connection is made, unless he is receiv- ing electrical sensation. *It must be conceded here that some Faradic machines give such a strong current with the plugs in L-R, and tJie sliding sheath clear in, that they are not amenable to the expedient here suggested. Such machines do not make good pulp testers. 50 SPECIAL POINTS IN TECHNIC 51 Steady the Hand To make the imperfect, moisture contact, one must steady the hand by supiDorting it with the fingers against the patient's face or teeth. However, the hand manipu- lating the dental electrode should always be steadied in this fashion whether one is making the moisture contact or ordinarv contact. Fig. 24. — Moisture contact, not actual contact. Keep Teeth Moderately Dry The teeth being tested should be kept moderately dry ; with cotton rolls Avhen neeessarj^. Otherwise the current 52 ELECTEO-EADIOGRAPHIC DIAGNOSIS may pass into the gum, pericemental membrane and ap- proximating teeth, through the saliva. The writer finds from experience it is not necessary to keep the teeth as dry as he at first supposed necessary. Cotton rolls are rarely necessary for upper teeth. For the lower teeth, instruct the patient to "raise the tip of the tongue to the roof of the mouth," then place the cotton roll and instruct the patient to ''forget about the tongue." The cotton thus applied is as useful as a means of keeping the tongue away from the teeth as to keep them dry. Use plenty of cotton, tightly rolled, un- der the tongue. Only about one fourth as much cotton can be placed on the buccal (facial) side of the teeth as can be placed on the lingual side. Unruly Tongues In cases where the tongue is very unruly, pushes the cotton out of the mouth, insists on covering the teeth when the operator wishes to apply the electrode, if the operator will allow the electrode to touch the unruly mem- ber, accidentally (?), once or twice the patient not infre- quently acquires a sudden and very fortunate control over the unruly lingual member. Wrapping the Dental Electrode It is apparently a very simple thing to Avrap the point of the dental electrode with cotton, just as the whole technic of electric pulp testing is simple, yet how easy it is to do it wrong, and therefore how often it is done wrong. A sufficient amount of cotton to cover the metal well and leave a little pad on the end should be wrapped tightly about the exposed metal. Rest the cotton be- tween the fingers and thumb of the left hand and turn the instrument to wrap. If the cotton does not wrap about the metal readily, flatten the sides with a stone or file. This is better than SPECIAL POIXTS IN TECHNIC 53 nicking the metal witli a file; the cotton goes on the flat- tened electrode just as readily and comes off easier. (See Figs. 25 and 26.) Twisting the cord, and the consequent danger of break- ing it may be avoided by disconnecting the electrode from the cord while the cotton is wrapped on the former. l-ig. 25. Fig. 26. Fig. 25. — Showing how the cotton should be wrapped on the dental electrode. Fig. 26. — Wrong way to wrap the dental electrode with cotton; too much cotton too loosely wrapped. 54 ELECTEO-EADIOGRAPHIC DIAGNOSIS The Application of the Dental Electrode to the Various Teeth It does not make a great deal of difference which par- ticular part of a normal tooth is selected as the spot on which to apply the dental electrode. However, the writer finds himself following the selection indicated by the table Selection of Spot for the Application of the Den- tal Electrode when fillings do not interfere with such selection. Selection of Spot for the Application of the Dental Electrode Anterior Teeth First choice: the labial surface V Second choice: the incisal edge Upper and Lower [ Tj^^^d choice : the lingual surface Upper Bicuspids And Molars First choice: the lingual surface (near summit of lingual cusps, at first) Second choice : the buccal surface Third choice: the fossse Lower Bicuspids j First choice : Buccal or ling-ual surface near occlusal And Molars | Second choice : the fossae Using Side of Dental Electrode If touching the tooth with the end of the electrode (Fig. 27) does not produce sensation, lay the side of the electrode against the surface of the tooth (Fig. 28). By gaining a greater area of contact more electricity enters the tooth. Keep Away from Gum Tissue When applying the side of the electrode to facial or lingual surfaces of teeth, take care not to allow the end of the electrode to approach too near the gum line as the current may pass through moisture into the gum tissue. Take care not to mistake sensation caused in this manner for sensation due to a vital pulp; there is a difference in the character of the sensation. SPECIAL POINTS IN TECHNIC 55 When to Apply the Electrode to the Lingual Surface of Anterior Teeth When sensation cannot be gained by applying the elec- trode to the facial surface or incisal edge of an anterior tooth, apply it to the lingual surface, where the covering of tooth structure over the pulp is not so thick. (Fig. 14 is of the correct shape to reach the lingual surfaces con- veniently.) Fig. 27. Figs. 27 and 28. — If a contact like that illustrated in Fig. 27 does not give sensation, try a contact like that shown in Fig. 28. The greater area of contact in Fig. 28 makes it possible for more current to enter the tooth. In Fig. 27 only the point of the electrode touches the tooth; in Fig. 28 the side of the electrode touches. When and How to Apply the Electrode to Fossae When sensation cannot be gained by aiDplying the elec- trode to the cusps or facial or lingual surfaces of the pos- terior teeth, apply the electrode to a cusp, then slide it down into the fossa slowly. The presence of a large fill- ing may make this procedure imiDracticable. 56 ELECTRO-RADIOGRAPHIC DIAGNOSIS How Much Sensation (Pain?) to Cause It is best to use enough current to cause the patient to jump or flinch involuntarily; slightly, but definitely. My interest was thoroughly aroused when I read the following in an advertisement for a pulp tester: ''En- ables you to detect devitalized teeth with certainty and Fig. 28. speed and ivithout causing pain." Considering my ex- perience with other pulp testing machines this adver- tisement led me to believe that the manufacturers meant to say to me that they had a machine different from the pulp testing machines I had used in that it did not cause pain like other electric pulp testers. Investigation, however, proved that the pulp testing machine adver- tised was not different from others. It caused the same SPECIAL POINTS IN" TECHNIC 57 sort of sensation caused by all electric pulp testers. Whether it caused only a '^distinct sensation" as claimed, or a slight pain is merely a matter of diction, merely a matter of Avhat you choose to call the sensation. Can any one tell just where "distinct sensation" leaves off and slight pain begins? The manufacturer evidently believes we should say "distinct sensation" rather than "slight pain" and I am inclined to agree with him, but patients, I fear, will continue to call it pain. Person- \ ally I should describe the sensation as a warm, stinging' sensation, very slightly painful or very definitely pain- ful, depending on the strength of the current. Do not Touch Tongue, Lips, Cheeks or Gums with Dental Electrode Take care not to touch the patient with the dental elec- trode anj^where but on the tooth to be tested as the sen- sation would be unpleasant. Hence the necessity of a dental electrode perfectly insulated except at its end. The fingers and a mouth mirror are used to hold back tongue, lijDS, and cheeks. Crowned Teeth Crowned teeth cannot be tested. Sensation is always produced whether the pulj^ is vital or not, if the crown is a gold shell. If the crown is one of the post-in-the-canal variety, testing is unnecessary for we know the ]3ulp is not vital. I have attempted to test only a comparatively few teeth with porcelain jacket crowns, and have found it impossible to get a reaction: the porcelain acts as a \ non-conductor. Testing Teeth with Large Metal Fillings Teeth with large metal fillings cannot be tested at all if the filling is so large there is no spot of sound enamel to which the dental electrode may be touched. However, when there is a spot of sound enamel to which the dental 58 ELECTKO-RADIOGEAPHIC DIAGNOSIS electrode may be applied teeth with large fillings can be tested much more successfnlly I find from experience than one would imagine. Metal Fillings Which Should Not be Touched with Dental Electrode When testing a tooth with an approximo-occlusal or an approximo-incisal filling, or any filling passing beneath the gum margin or touching an approximating tooth, do not touch the filling — touch the enamel only. Also avoid touching unsupported enamel with a metal filling just under it, as the effect is about the same as touching the metal, i.e., there will be a sharp positive reaction whether the pulp is vital or not. Rubber Dam Insulation When testing teeth with approximo-occlusal or ap- proximo-incisal fillings in them, two or more thicknesses of rubber dam may sometimes be placed between the fill- ing and the tooth approximating the filling. If kept dry, the rubber acts as an insulation, keeping the current from passing into the approximating tooth. I find, however, as I develop a better technic and judgment I am able to discontinue the use of this rubber dam insulation. When and How to Touch a Metal Filling with the Dental Electrode A tooth with a small, simple filling surrounded by sound enamel, which does not come in contact with the gum tissue or approximating tooth, may be tested by touching the dental electrode to the filling. When this is done, the current should he weak; also it is best to apply the electrode to the enamel and slide it cautiously toward the filling. SPECIAL POINTS IN TECHNIC 59 If tlie filling is large, even tliongli it does not come in contact with the gum tissue or approximating tooth, it is not expedient to touch it with the dental electrode. If the pulp is vital, the pain produced may be very intense, if it is not vital, sensation is sometimes nevertheless caused owing to the attraction the big bulk of metal filling material has for the current, receiving it in such quantities it is transmitted to the pericemental membrane and contiguous tissues or in some cases perhaps trans- mitted by moisture through unfilled canals to the periapi- cal tissues. Unsupported Enamel Avoid touching unsupported enamel. If it overlies a filling substantially the same effect is produced as though the electrode were applied directly to the filling, and if it covers a carious cavity the current passes through it into the cavity and so through moisture into the pulp, produc- ing a violent reaction if the pulp is vital. Even if the pulp is not vital a reaction usually occurs from touching unsupported enamel over an approximo-occlusal carious cavity; the current passes into the moisture in the cavity and thus into gum tissue, pericemental membrane and ap- proximating tooth. Trouble: No Current The first time it occurred it puzzled me: the machine (one of the Faradic type) was humming as it should, the patient held the hand electrode, the dental electrode was moist. I applied the dental electrode and advanced the current controller from the minimum to maximum; no reaction. I tried another tooth and another and another; still no reaction. I took the hand electrode in my own hand and with the current controller at minimum applied the dental 60 ELECTRO-RADIOGRAPHIC DIAGNOSIS electrode to the fleshy base of my thumb; no sensation. I advanced the current controller; no reaction. I fingered about all the connections where the cords fasten to the machine and electrodes. Then, with the current controller again at minimum, tried the test on myself again; Ah, sensation! "Evidently one of the connections is loose," thought I, and proceeded to test the patient's teeth. One tooth was tested, then another, then again I had no current. Fig. 29. — Showing where cords wear out and break A and one reason B why they break here. Some tips or plugs are made so that they may be unscrewed and the cord repaired by cutting and re-attaching at the tip. Cords break as they enter the tips at their electrode ends also. Then it occurred to me that perhaps the wire inside of the insulation was broken at A, Fig. 29 as a result of plugging the cords into the machine as indicated in Fig. 29, B. Such proved to be the case; I could establish a connection between the broken ends of the wire inside the insulation by pushing the cords into the metal tips slightly, and break it again by pulling on the cords just a little. Let me say emphatically that such a cord with a broken wire should not be used. Even though punching the cord SPECIAL POINTS IN TECHiSTIC 61 toward the metal tip may bring tlie broken ends of the wire in contact, a slight movement of the cord may sepa- rate them again and another slight movement bring them together again. So Avitli this sort of thing going on ob- viously one can scarcely tell Avhen a tooth fails to respond, whether it is because the pulp is not vital or because the ends of the broken Avire have been separated momenta- rily. Testing Out the Machine Whenever there is an}^ doubt at all as to whether the machine is producing current, let the operator take the hand electrode in his left hand and touch the dental elec- trode to the fleshy part of his thumb of the same hand as suggested above. Have the current regulator at mini- mum to start with at least. Tracing" the Current When Shock Occurs Changing Plugs For a shock to occur when changing plugs the condi- tions must be as follows: (1) The main switch must be closed, and the interrupter vibrating. (2) The patient must be in contact Avith the indifferent electrode. (3) The plug, Avliere the operator grasps it, must be an elec- tric conductor, i.e., metal. (4) The ojDerator must take hold of the plug which is connected (by the cord) to the dental electrode. (5) The operator must be in contact with the patient. Shocks occurring when j)lugs are changed may be avoided in a number of Avays, as many Avays as there are requisites for the shock to occur. (1) By opening the main SAvitch. This is rather impractical. (2) By liaAang the patient lay doAAm the hand electrode. This too is im- practical. (3) By liaA^ng insulated plugs. This is practi- cal. (4) B}^ changing the plug connected Avitli the in- different electrode. This is sometimes practical, some- 62 ELECTRO-EADIOGEAPHIC DIAGNOSIS times not. (5) By the operator severing all electrical con- nection with patient before touching plugs. This will "work," but is a nuisance. In fact the whole procedure of changing plugs is a nuisance, as stated under the head- ing "A Valuable Point in Technic." The course of the current when shock due to plug changing occurs is as follows: From the machine to the patient, through the indifferent electrode. From the pa- tient, through the operator's hand or metal mouth mirror (in contact with the patient), through the operator's hand which grasps the plug, and thus back to the ma- chine, or following the same path in the opposite direc- tion. TECHNIC ILLUSTRATED (Figs. 30 to 41) Even my technic is not always exactly as shown in the following illustrations. The illustrations are shown not with the idea that the reader shall always do just as il- lustrated. However, no written description of how to do a thing can be as efficacious as to show how to do it. Therefore these illustrations, I feel certain, will be quite helpful. There are no illustrations in this series showing the ap- plication of the dental electrode to the incisal edges and occlusal surfaces. By illustrating the application of the electrode to the facial and lingual surfaces all essential points in technic are demonstrated. It seems obvious to the writer but it may be mentioned, however, that it is the point of the electrode usually which is used when it is applied to incisal edges and oc- clusal surfaces. Read the legends under the illustrations from Fig. 30 to Fig. 41 inclusive. Figs. 30 to 41 show the positions of the hands, mouth mirror and electrode when the latter is applied to the different teeth. It is my habit to hold the mouth mirror in the left hand even when it is not in use. SPECIAL POINTS IN TECHNIC 63 The position of the operator is to the right and just back of the patient, i.e., the usual dental operating posi- tion. Most all of the teeth can be reached from this position. It may be found advantageous to step forward from the usual position and face the patient to reach the right posterior teeth, particularly the buccal surfaces of the upper second and third molars. Notice that the hand that holds the electrode is always supported — "guarded" to use the word usually used in this connection— against the teeth or face, so the elec- trode may be applied exactly to the right spot of the right tooth. In several of the illustrations, from Fig. 30 to Fig. 41, the cotton on the electrode has been discolored with iodin to make it show plainer against the white of the teeth. Fig. 30. — Applying the electrode to the labial surface of an upper anterior tooth. The cotton on the electrode point is stained with iodine to make it show plainer in the illustration. 64 ELECTRO-EADIOGRAPHIC DIAGNOSIS Fig. 31. — Applying the electrode to the lingual surface of an upper anterior tooth. The operator "works to image," i.e., he sees the end of the electrode and the lingual surfaces of the teeth in the mouth mirror. SPECIAL POINTS IN TECHNIC 65 Fig. 32. — Applying the electrode to the buccal surface of an upper left posterior tooth. Note how the mouth mirror is used to hold away the cheek and how the hand holding the electrode is steadied by placing the fingers against the upper anterior teeth — also resting slightly against chin. 66 ELECTRO-EADIOGRAPHIC DIAGNOSIS Fig. 33. — Applying the electrode to the lingual surface of an upper left posterior tooth. SPECIAL POINTS IN TECHNIC 67 Fig. 34. — Applying the electrode to the buccal surface of an upper right posterior tooth. Position of operator is farther forward than usual for other teeth. Note electrode hand is supported against lower teeth and chin. ELECTRO-EADIOGEAPHIC DIAGNOSIS Fig. 35. — Applying the electrode to the lingual surface of an upper right posterior tooth. Working to the image in the mirror. SPECIAL POINTS IN TECHNIC 69 Fig. 36. — Applying the electrode to the labial surface of a lower anterior tooth. 70 ELECTRO-RADIOGRAPHIC DIAGNOSIS Fig. Z7 . — Applying the electrode to the lingual surface of a lower anterior tooth. SPECIAL POINTS IN" TECHNIC 71 ^^^0^^^ -'^^^ ^H I^F _.v*:#^ .,^ > * M ^ f < / j^ V Fig. 38. — Applying the electrode to the buccal surface of a lower left posterior tooth. Note the cotton roll under the tongue. There is also a small roll of cotton in the vestibule of the mouth. The mouth mirror is used to retract the cheek. 72 ELECTRO-RADIOGRAPHIC DIAGNOSIS Fig. 39. — Applying the electrode to the lingual surface of a lower left posterior tooth. Cotton under the tongue and in the vestibule of the mouth. Here the mouth mirror is used to reflect light onto the field of operation; the middle finger of the left hand retracts the cheek. SPECIAL POINTS IN TECHNIC 73 Fig. 40. — Applying the electrode to the buccal surface of a lower right posterior tooth. The mirror is holding the cotton and tongue down. 74 ELECTRO-EADIOGRAPHIC DIAGISTOSIS Fig. 41. — Applying the electrode to the lingual surface of a lower right posterior tooth. The cheek and face serve as a support for the hand holding the electrode. The mirror retracts the tongue. Cotton under tongue and in vestibule of mouth. Electrode hand retracts cheek. CHAPTER VI THINGS WHICH MODIFY THE STEENGTH OF CURRENT NECESSARY TO TEST TEETH In tlie same month some teeth will reqnire more cnrrent than others. This varies somewhat in proportion to the size of the tooth. However, it is quite impossible to es- tablish the ''irritation point" (the point where definite sensation is prodneed) of the various teeth with mathe- matical precision. To sa^^, for example, that the ' ' irrita- tion point" for lower incisors is one (scale 1 to 10, mini- mum to maximum, of the current controller), of upper incisors, two, of upper cusjDids, six, of upper molars five and so on. There are too many factors which modify the streno'th of the current needed to admit of making such a table. A List of Factors Modif5dng Stren^h of Current Needed Some of these factors are: (1) Age of the patient. (2) Thickness of the enamel. (3) Condition of the patient. (4) Moisture. (5) Secondary dentin. (6) Pulp stones. (7) Abrasion and erosion. (8) Carious cavity. (9) Im- munity to current. (10) Fillings. (11) Size of tooth. (12) Pericementitis. Age of Patient The younger the jDatient, the larger the pulp, and so the shorter the distance to it through the tooth. Hence less current is required. Thickness of the Enamel The thickness of the enamel varies in different indi- viduals, in various teeth, in different locations on the same 75 76 ELECTEO-EADIOGEAPHIC DIAGNOSIS tootli. The thicker the enamel, the more current re- ciuired. This is particularly noticeable in the upper cus- j)icl Adhere the enamel is quite thick. Most teeth in the mouths of adults are worn through the enamel at some place or places. Condition of the Patient Not infrequently the test is applied in cases where the patient has been taking some narcotic to relieve pain. More current is required in such cases and the Avriter re- calls having a case where large doses of codein had been taken and no response at all could be obtained from the application of the electric test at the cai)acity of the ma- chine. This case and one other — a case in which there was a luetic central nerve lesion — are the only cases thus far encountered where the "irritation j^oint" could not be reached. It is well known that alcohol has a narcotic effect and so a patient under its influence requires more current. Neurotic patients will recpiire less current than patients of a more phlegmatic temperament. Moisture Teeth which are thoroughly dry will require more cur- rent than those which are somewhat moist. Thus the lower teeth take somewhat less current than the upper. Also the amount of current necessary will vary with the moisture of the cotton on the dental electrode; the drier the cotton becomes, the more current necessary to pro- duce a given effect. Secondary Dentin As a pulp recedes, throwing up secondary dentin, the current required to reach and have an effect on it nat- urally increases. STRENGTH or CURRENT 77 I have noticed repeatedly that, though the upper lateral incisors are smaller than the centrals, the laterals require more current to reach their irritation point. Perhaps the upper laterals, from some cause of which I am in ignor- ance, are more likely to develop secondary dentin, (this seems probable) or, it may be the enamel on them is com- paratively thicker than on the centrals, or, it may be be- cause their nerve supply is less generous and less direct than the centrals. At any rate it may be accepted as a clinical fact, and an exception to the rule that the amount Fig. 42. — In some cases it may be expedient to make an opening through the enamel to apply the dental electrode. The advantage in this over simply drilling to the point of sensitivity is that there is less danger of accidental exposure. of current varies directly with the size of the tooth, that upper laterals usuall}^ require a sliglitlij stronger cur- rent than upper centrals. In some cases of secondary dentin where the pulp is vital it is impossible to get any response at all from the application of the electric test. In such cases a small diagnostic opening may be made Avitli the dental burr through the enamel, one or two millimeters into the den- tin (Fig. 42) and the dental electrode applied to the dentin in this way. If the pulp is vital a response to the 78 ELECTRO-RADIOGEAPHIC DIAGISTOSIS electric test can be obtained in this way. In order to carry ont tliis suggestion, the dental electrode must have a point or working end of the right size and shape (Fig. 14). Pulp Stones Occasionally teeth with pulp stones require more cur- rent, unless there is pulpitis, when less current is re- quired. It is sometimes expedient to make a diagnostic opening into the dentin, tlieii apply the test, as just sug- gested under the heading "Secondary Dentin." Abrasion and Erosion As a rule less current is required on abraded and eroded surfaces because there is less or no enamel to penetrate. If the abrasion or erosion has caused the pulp to recede and throw up secondary dentin, the presence of the secondary dentin may compensate for or, in rare in- stances, more than compensate for the loss of enamel. Carious Cavity A tooth with a carious cavity in it should be tested care- fully, applying the electrode to a point on the surface of the tooth as remote as possible from the cavity. Even when this is done, taking them as a class of teeth, teeth with carious cavities in them require less current than teeth without cavities. (The current seeks the cavity through moisture.) Immunity to Current Practically all patients will claim to be particularly susceptible to electric shocks. While I am perfectly well aware of the fact that some patients can "stand" more electricity than others and try never to lose sight of this fact, and am now in fact directing my reader's attention STKEXGTH OF CUEEEXT 79 to it, I nevertheless know tliat each patient who claims especial susceptibility is not the exception he thinks he is. True exceptions of subnormal susceptibility are more common, I find, after making allowances for fright, than cases of supernormal susceptibility. Electricians, men who work with electric currents constantly, are often sub- normally susceptible, requiring excessive doses of the cur- rent to get a reaction. It is common knowledge that apx)lication of an electric current will result in an acquired tolerance. We notice this in the application of the electric test for pulp vitality. I have had this experience repeatedly: I start to test a given tooth with the current controller at minimum to avoid undue pain. The controller is gradually advanced, touching the tooth at each advance of two or three points on the scale, until the controller stands at maximum. Xo definite reaction, i.e., no definite sensation, is produced. After a Avait of a few minutes the test is again applied, this time starting with the current controller at maxi- mum, and now there is a definite, unmistakable reaction. The tooth did not respond Avhen touched with the control- ler at maximum the first time because of the immunity or tolerance acquired as the controller was gradually ad- vanced. Fillings As stated elsewhere, unless there is a sj)ot of sound enamel to which the dental electrode may be ai)plied, the tooth with the large metal filling cannot be tested. Fillings of moderate size do not interfere materially witli the application or accuracy of the test. Take them as a class of teeth, however, and it will be found that teeth with moderately large fillings require slightly more current. This is due likely to the fact that the stimulus of a metal filling produces secondary dentin. 80 ELECTRO-EADIOGEAPHIC DIAGj^OSIS The possibility of the current traveling from the point of application of the dental electrode, through the tooth, into a metal filling and through it into an approximating tooth, the gum tissue or the pericemental membrane, is undeniable. But, in practice, I find I do not have this trouble. I grant that such a thing might — must — occur, but in practice it seems not to occur sufficiently to cloud diagnoses. Eubber dam may be used as an insulation as previously suggested, if desired. When I first started to use the test I used the rubber dam insulation frequently but I have not found it necessary to use it recently. The possibility of the current traveling from the point of application of the dental electrode, through the tooth, into a metal filling, through it into a metal post in the canal and through the side of the root into the pericemen- tal membrane, is likewise eminently possible from a theo- retic standpoint. But from a practical, clinical standpoint this seems not to occur; thus far it has not occurred in my jDractice, except once where the post extended through a perforation in the side of the root. If one should touch the metal of a large filling, or unsupported enamel just over metal, sufficient current to cause pain would promptly reach gum tissue, pericemental membrane or an approximating tooth; but this would be a violation of correct technic. Pericementitis A tooth with a dead pul^D, and severe pericementitis is said to respond to the electric test for pulp vitality. From a theoretic standpoint this should be true but fortunately in practice it seems not to be. In my own practice I have never been misled to believe a pulp vital by getting posi- tive reaction from an inflamed pericemental membrane. Pressure against the tooth transmitted to an inflamed l^ericemental membrane will, of course, cause pain. So STRENGTH OF CURRENT 81 the electrode should not be pressed against the tooth. Make a moisture contact if necessary to avoid pressure. Differentiation Between Pulpal and Gin^val Sensation Recently 1 was testing an upper right second molar with a large filling. The tooth was very short occluso- gingivally. The only spot of sound enamel to which the electrode could be applied was on the mesio-lingual. I started with the current low, touching the tooth at inter- vals, and advanced the current controller to maximum. There w^as no sensation at all until the maximum current was used, and then the response was only a very weak positive (+VW). As I have said, the tooth was very short. This, coupled with the very weak response to the maximum current, made me wonder whether the response I had received was from a vital pulp or whether some of the current had leaked into the gum. I retarded the current controller to almost zero, ap- plied the electrode to the enamel on the mesio-lingual, then slowly pushed the point of the electrode toward the gum until it almost touched it, when the j^atient regis- tered sensation. I said to the patient: "Did that feel like it did a mo- ment ago, when I touched the tooth before?" The patient replied: "Oh, no. This last was different. It was — ^well, it was quite different." Of course the patient did not know that the first sensa- tion was caused with the electrode on enamel as far from the gum and metal filling as possible and with the cur- rent controller at maximum, while the second sensation was produced with the dental electrode forming a con- tact, by moisture, with the gum tissue. The patient knew none of the details. All she knew was that the second time she received sensation it was "Oh, quite different from the first." 82 ELECTEO-EADIOGEAPHIC DIAG^S'OSIS Because of the difference in the essential nature of the sensation proclnced in the gum tissue, compared to that at first produced by touching enamel, I deduced that the first sensation came from a vital pulp. Radiographic findings bore me out in this opinion. This is the only case in which I have tried to differ- entiate between pulpal sensation and gingival sensation by deliberately moving the electrode along the side of the tooth to an electric contact with the gum. The pro- cedure gave desirable results in the one case in which it was tried and, it seems to me, it gives promise of con- siderable clinical value in cases where the operator is un- certain wdiether the sensation he produces is due to a vital pulp or leakage of the current into the gum. I have found also that when there is a sensation pro- duced in a pulpless tooth by a slight leakage of current into a large metal filling, the patient will often say, if questioned, ''But that was different from the others," meaning different from the sensation produced in other teeth tested in which the pulps were vital. I recall the old question, a fine one to argue about if you like to argue: ''Are pain and touch separate and distinct senses, or is pain simply a form or manifestation, a sort of hyperesthesia, of the sense of touch ?" I recall also that there are men who say that the dental pulp has no sense of touch, only the sense of pain. I do not open these old questions to argue them. All I wish to say here is that the sensation in the dental pulp produced by the electric current is different, sharper, than that produced in the gum. Of course a considerable amount of current in the gum Avill produce a "sharp" sensation. CHAPTER VII LIMITATIONS Every test, everything, for that matter, has its limita- tions. The most outstanding limitations of the electric test for vitality of the dental pulp are : (1) Crowned teeth cannot be tested. (One must con- tinue here to use the thermal tests which the electric test so nearly displaces altogether, or make a diagnostic opening.) (2) Some teeth with very large fillings cannot be tested successfully. Fortunately there are not many such teeth. (3) In multirooted teeth, where the pulp in one canal is vital and in another nonvital, the response to the electric test is practically the same (a little weak) as though all parts of the pulp were vital. (4) One is doing well to determine, from the electric test, simply whether the pulp is vital or not. Even this cannot always be done. The average operator (the writer includes himself in this class) will find it impossible, ex- cept in the rarest cases, to diagnose pathologic states of the pulp with the electric test. One is treading on treacherous ground indeed when, after applying the elec- tric test, one makes bold to say, ^'This pulp is vital and in a state of normality or health, and this one is also vital and much inflamed with pus infiltration." It is not practical. A small booklet "Electro-Diagnosis of Diseases of the Pulp" has recently come to my attention. It is published by a manufacturer of electric pulp testing machines and, in the main, is quite a worthy little essay on the subject of testing pulps for vitality with electricity. However, the idea of diagnosing pulp diseases — not simply deter- 83 84 ELECTEO-EADIOGEAPHIC DIAGNOSIS mining Avlietlier the pulp is vital or not, but diagnosing pnlp diseases — seems rather "far fetched." I quote the following : "The following scheme may serve as a guide for mak- ing a diagnosis: 1. The normal pulp responds to the cur- rent at the irritation point. 2. The irritated pulp re- sponds to the current at the irritation point, or just slightly below it. 3. The inflamed pulp responds to the current below the normal irritation point. The more se- vere the inflammation, the more ready the response to the current. 4. The inflamed pulp with pus infiltration (abscess formation) responds to the current above the normal irritation jDoint. The more severe the purulent condition, the less read}'" the response to the current. 5. The dead pulp does not respond at all, not even to the full strength of the current." My advice to anyone Avho reads the foregoing is to dis- regard it. If 3^ou do not it seems to me it will confuse you hopelessh^ Do not tiy to diagnose diseases of the pulp with the electric test; tiy onl^^ to learn whether or not the pulp is vital. Do not think that one type of pulp testing machine Avill enable you to gain such perfect results that you can diag- nose pulj) disease, while other t^^pes of machines enable 3^ou onl}^ to ascertain whether the pulp is vital. It is the nature of the test itself, not the nature of the i)ulp testing machine, that makes such fineness of diagnosis as outlined above impossible. I quote from the above: "The inflamed pulp responds to the current below the normal irritation point. The more severe the inflammation, the more ready the re- sponse to the current." Quite true, an inflamed pulp reacts more shari^ly and to less current than a normal pulp. But suppose Ave have the combination of an inflamed jDulp and secondary den- tin — a not at all unusual combination? It takes less cur- LIMITATION'S 85 rent to reach tlie irritation point of an inflamed pnlp, bnt it takes more current to reach the irritation point in a case of secondary dentin. So if we have both an inflamed pnlp and secondary dentin, the one condition may can- cel the other and the inflamed pnlp react like a normal one. I cjnote again: "The inflamed pnlp with pns infiltration (abscess formation) responds to the cnrrent above the normal irritation jDoint. The more severe the pnrnlent condition, the less ready the response to the cnrrent." A semivital pnljD reacts less sharply and requires more current than a normal jDulp. But suppose the dental elec- trode is applied to a spot on the tooth where the enamel is quite thin. Then the semivital pulp may react like a normal pulp. One might continue citing case after case ad iufinitiim to demonstrate the futility of lioj)ing to diagnose pulp disease with the electric test. Just a word further though. Let us imagine we stand Avatching an operator apply the electric test. Suddenl}^ he gets a severe reaction, the patient jumps violently, though the current used was no stronger than that used on several adjoining teeth. Ah ! he has touched a tooth with an inflamed pulp! But has he! Perhaps, instead, the dental electrode has been ap- plied to unsupported enamel, or to a metal filling, or it has come too near the gum, or it has touched a sjiot of thin enamel or exposed dentin, or perhajDS the current has traveled through moisture into a gum-covered carious cavity or into a fault in the enamel such as a fissure or pit. But are we not agreed that the electric test is a means of determining pulp vitality, not a means of diag- nosing pulp diseases ? CHAPTER VIII APPLYING THE TEST FOR NERVOUS PATIENTS Electropliobia (fear of electricity) is universal. As stated in Chapter VI practically all liuman beings are afflicted; there is difference merely in degree. When the electric test is suggested many patients will offer strenuous objections saying ''I cannot stand elec- tricity. ' ' The Psychology of the Situation Before the operator proceeds with the application of the test he should take into account this mental attitude of the patient and try to overcome any undue anxiety or fear. The test is not accompanied with sufiflcient pain for any- one who knows what it is like to dread it. But the oper- ator must not lose sight of the fact that his patient may not have the slightest idea of what the test is like and imagine it very dreadful. The handling of this situation will vary with different patients, but is fundamentally the same in all cases. The psychologic problem is a comparatively easy one and is simply that of removing or lessening excessive fear of the unknown. Test Harmless When the patient fears that some permanent injury may be done the teeth by the test one cannot be too em- phatic in assuring such a patient that no harm will be done. The fact is that the test is absolutely harmless. Let us imagine we are applying the test in the case of a particularly nervous patient. APPLYIISTG TEST IN" NERVOUS PATIENTS 0< A Sort of Written Clinic Tlie conversation given hereinafter is subject to great variation. It is not intended as a verbatim account of what should be said. It is a sort of written clinic. We proffer the patient the hand electrode asking him to take it. He pushes it away or takes it testily, saying, ''What's that!" We say something like this: "Don't be afraid; you will not feel anything in your hand ; you will not feel anything at all anywhere until I tell you about it. Take it. ' ' We hand the electrode to him, often closing his fingers over it as we speak. With the patient holding the electrode we continue, ' ' Now we want to test your teeth to see whether the pulps are vital." "What is it? Electricity? I can't stand electricity!" This from the patient. "It will not feel like electricity. You will not feel it in your hand at all you know, and whether you can feel it in your tooth or not is what we want to find out. If you feel it in your tooth at all it won't feel like electricity. There will be just a little sting (like when you are having a tooth prepared for a filling, only not nearly so severe). "We touch the tooth only for a moment, see, like this." The operator touches his own fingernail Avith the dental electrode and removes it two or three times to demon- strate that the application of the electrode to the teeth is only momentary. "You are not to even tri/ to stand any pain. We want you to tell us — flinch or say 'huh' — just as soon as you feel it tingle the least bit. This is different from any other kind of dental work; you see we can stop as soon as you feel it. There 's nothing more to do then, nothing we have to do whether it hurts or not. ' ' "We Avill start Avith the current so weak, you Avill hardly feel it, if you feel it at all." 88 ELECTEO-EADIOGEAPHIC DIAGXOSIS As iDrevioiis]}^ stated, wlien tlie machine lias three sockets or binding posts, I use the tester ahvays with the cords plugged into L and R (1-3) . It is very anno^dng and impractical to make changes in connections to modify the current strength. So with the cords plugged into L-R, and the current regulator at minimum we are ready to demonstrate the truth of our assertion to the patient that the test can he applied with the current so weak it will scarcely be felt, if felt at all. Since we are keeping our j^lugs in L-R (1-3) our cur- rent is not as weak as it could be made, not as weak as it would be in L-M (1-2) or M-R (2-3) and so we must resort to some means, other than the changing of plugs, to keep our current sufficiently weak. (In this connection it must be conceded again that there are some Faradic machines which simply give too strong a current to keep the plugs in L-R (1-3).) This may be done as follows : Dip the cotton-wrapped end of the dental electrode in water or the sodium chlorid solution, then exjDel all the moisture from the cotton again by pressing it against a piece of white blotting paper or a napkin. Thus, if the patient is observing our actions, he sees us go through the same procedure ordinarily fol- lowed, except — and it is very unlikely that he will notice this — we press the moistened cotton against the blotting- paper expelling practically all moisture, instead of simply toucldng the blotting jDaper to take up excessive mois- ture. With the cotton on the electrode dry, or almost dry, it is not a good conductor, so when applied to a tooth only slight sensation, if any, is produced. If the machine can be graded to zero by the current regulator, all this is unnecessary. Usually, as soon as the patient learns that a tooth can be touched with the dental electrode without producing extreme pain, their excessive fear is gone. APPLYIIv^G TEST I]^ aSTERVOUS PATIENTS 89 Just as soon as the patient registers liaving received sensation — by sound or flinching — stop and say, "Now you know what it is like — you know all about it." The Imperfect Moisture Contact The trick (or expedient, if you like the longer word better) of making the imperfect, moisture contact is of the utmost value. It would be impossible to test teeth, and get reliable results, for some nervous patients if it were not for this "stunt in technic." For a description of the technic of making this contact see Chapter V under the heading "A Valuable Point in Technic." Only a Few Patients Difficult to Handle I regret having failed to make my consideration of the handling of patients shorter. I fear I may lead my read- ers to believe the application of the electric test is always attended with considerable difficulty and the necessity for much explanation, which is not the case. Offer No Explanations or Comments Unless Necessary The foregoing is calculated to teach the beginner to meet any emergency which may arise. Let it be clearly understood that it is not advisable to give any sort of ex- planation to a patient unless the patient's state of mind is such as to make it necessary. A¥hen the patient is not afraid it is obviously unnecessary to take steps to re- lieve fear. Indeed such a course would create fear where it had not existed. Talk to the patient about the test as little as possible, but as much as necessary. As the oper- ator becomes more skillful in the use of the test he will find less need for conversation with his iDatient regarding it. 90 ELECTRO-RADIOGRAPHIC DIAGNOSIS Children As far as possible I treat cliildren as tliougli they were grown-ups. The most notable exception is to say to a good natured, unafraid child something like this: "Now this thing will tickle a little bit. I want you to tell me Avlien you feel it start to tickle and I'll stop. I just want to see if your teeth are alive by finding out if they are ticklish." The use of the word ''tickle" has a splendid psychologic effect, and if the operator is careful he need cause no more sensation than the child will accept as ''ticklish." If the child is too ill-natured or too afraid, this effort at suggestion will fail, but it usually "works" beautifully. CHAPTER IX ANSWERING ADVERSE CRITICISM Comparatively little has been Avritten on the subject of tlie electric test for pulp vitality. What has been written has been by men who use the test and believe in its effi- ciency. Scarcely anything at all has been written in the way of constructive criticism, indeed hardly anything at all has been written in the way of any sort of criticism. Verbal criticism, hoAvever, is not at all uncommon. The only thing I am able to locate just now in the way of adverse criticism appeared in Dental Cosmos, October, 1918. I quote from this article: ''At a clinic all hands agreed that a certain tooth appeared to be devitalized. The pulj) tester was applied, and it gave positive and un- mistakable signs that the pulp was vital. A skiagraph was then taken, Avhich showed that the roots were filled ! ' ' Such reports as these fail utterly to convince or even to approach convincing the writer of the inadequacy of the electric test, for I ask myself such questions as these : Did the operator touch a metal filling? Did the operator touch the gum tissue? Did the operator touch unsup- ported enamel? Did the operator use the wrong kind of a dental electrode and touch the patient's lij) or cheek? Was the patient so nervous that he jumped without re- ceiving sensation? Was the tooth sore and was the elec- trode pressed against the sore tooth thus causing pain? Was the tooth covered with moisture and did the current travel through the moisture to an adjoining tooth! In short, did the operator know how to apply the test, for certainly the inefficiency of a test is not proved when it is applied by an inefficient operator ? 91 92 ELECTRO-EADIOGRAPHIC DIAGIS'OSIS I quote again from the article referred to above. It being the onl}'' written thing I have to attack, let me at- tack it in several places. I quote the following as an ex- ample of bad logic: "He was asked, 'Is the electrical test always positive!' He answered, 'No.' To the query, 'Is the thermal test always positive?' he replied 'No.' To the question, 'Then in a final analysis the only real way, in this the year 1918, to tell whether or not a pulp is dead or alive is to drill into iff the answer Avas 'Yes.' "And there 3^ou are!" Following this sort of reasoning one might claim that "the onh^ real way" to iDrevent insanity is to cut off the head. An autopsy is a "real way" of making a diagnosis but it is destined to remain a sort of a last resort. There are some teeth, the vitality of the pulps of which cannot be determined except by making a diagnostic opening, but there are millions, millions upon millions, the vitality of the pulps of which can be determined by the electric test, or by the electric test and the making of a radiograph. AVhile written criticisms of the test are scarce, verbal ones, as I have said, are far from scarce. Here is a typi- cal verbal one, addressed to me recently by one of my friends: "I applied the electrode to a simple occlusal filling and the reaction was positive and definite. I opened the tooth and found the pulp putrescent." I have no reason whatever to doubt the truth of such statements, but let us take a case such as the one just mentioned and apply our electric test before making a radiograph, making records of the application of the electric test. We will supj)ose it is a lower first molar. It is my custom to test at least the two teeth approxi- mating the tooth under examination. So, then, we test the second bicuspid and the second molar and find that both of them respond. We test the first molar, applying the electrode to the enamel and find that it does not re- ANSWERING ADVERSE CRITICIS:\r 93 s23ond. Accordingly, we make the current weaker and slide the electrode on to the metal of the occlusal filling; and let ns imagine that still the tooth does not respond. We increase the current and now we get a response. Under such circumstances shall we simply mark our chart positive for the first molar I By no means, I would mark such a tooth ''positive questionable" (+!) or per- haps make a special note under "remarks" saying "Pos- itive on amalgam filling, negative on enamel. ' ' Such records then would cast suspicion ujoon this tooth. Suppose now we go ahead and make a radiograph and we find the metal filling running to, or perhaps slightly into, the puljD chamber. AVe also find a very slight bone change, a slight osteoclasia, and a suggestion of osteo- sclerosis, at the apex of one of the roots. This bone change is not sufficient in itself to be taken as an indica- tion of periapical infection but couj)led with the other evidence we have gathered — manner of response to the electric test and the metal filling penetrating deeply to- ward the pulj) — this bone change may be taken as further evidence that the pulp is probably not vital. (The course of the current to produce sensation could be through the amalgam filling, through the moisture in the septic canals, out the apical foramina to vital tissue.) With such an arra}^ of evidence indicating a nonvital pulp certainly any diagnostician, worthy of the name, AYould suspect a dead pulp, even if there was response upon the aiDj^lication of the dental electrode to the metal filling. It just occurs to nie: I did not ask my friend why he opened the tooth. Perhaps he took into account some of the things I have mentioned, or perhaps subjective symp- toms were such as to cause him to open the tooth. And this reminds me to give warning that the electric test is not intended to take the place of all other diagnostic measures. Symptoms should be considered, of course. 94 ELECTRO-EADIOGEAPHIC DIAGNOSIS Everything considered: Tlie inadequate dental elec- trodes which have been used. The inadequate machines also. The erroneous idea that the technic for electric pulp testing requires almost no knowledge or skill, that the entire subject is covered in the eight fundamental steps in technic set forth in Chapter IV, in less than five hundred words. The unwillingness to accord the test and its technic sufficient respect. I say, everything consid- ered, the wonder is not that some men attack the test but that it is as popular as it is. CHAPTER X CLINICAL VALUE OF THE TEST There are many sorts of cases in which the electric test for pnlj) vitality may be applied to great advantage by the diagnostician. It is not jDossible to mention all the circumstances nnder Avhich its application Avill prove helpful, and, if it were, the mere mention of such circum- stances and cases w^ould fail to impress the reader or teach him so effectively as the illustrated description of cases. Nevertheless, some written effort to indicate the extent of the value of the test seems necessary and is set forth in this chapter. To get a fuller realization of the clinical status of the test, see the illustrations in the next chapter. The following is a list of cases and circumstances in which and under which the test may be used to advan- tage: (1) In cases of systemic disease to determine which teeth are most suspicious. (2) Where no x-ray machine is available. (3) To check all x-ray findings. (4) To find teeth wdth dead pulps which could not be found by any other means. (5) To find abscesses which might other- wise be overlooked because they fail to show in radio- graphs made at certain angles. (6) To assist in recog- nizing very slight osteoclasia. (7) To avoid mistakes when the end of a root and an abscess cavity (with no connection between the two) overlap in the radiograph due to the angle at which the exjDOsure is made. (8) To avoid misinterpretation when the abscess cavity laps to the lingual or facial of the adjacent teeth. (9) To differ- entiate between the mental foramen and an abscess cav- ity. (10) To differentiate between the anterior j^alatine, 95 96 ELECTRO-RADIOGEAPHIC DIAG^STOSIS or incisive, foramen and an abscess cavity. (11) To dif- ferentiate between tlie antrum of Higlimore and an ab- scess cavity. (12) To differentiate between the somewhat radiolncent area which sometimes appears in the apical region of upper lateral incisors, due to the canine, or in- cisal, fossae, and radiolucence caused by infection and pathologic bone change. (13) To differentiate between nostril spots and abscesses. (14) To aid in the recogni- tion of nasal fossae spots as such. (15) To aid in the rec- ognition of the inferior dental canal as such. (16) To differentiate between a very small abscess cavity and an unusually large periapical space. (17) To differentiate between a cancellous spot of unusual appearance and an abscess cavity. (18) To assist in differentiation between pathologic and physiologic conditions about the buccal roots of the upi)er molars. (19) To assist in differentia- tion between an absorbed, roughened root and a radio- graph made Avith the rays directed through the tooth diagonally from facial to lingual. (20) To differentiate between partially formed root and an abscess. (21) To determine how many teeth are involved in an abscess. (22) To assist in differentiation between dentoalveolar abscess and periodontoclasia (pyorrhea). 1. In Cases of Systemic Disease to Determine Which Teeth Are Most Suspicious The determination of which teeth are most suspicious aids in many ways. If the cost of examination is to be cut to the minimum those teeth which respond perfectly to the test need not be radiographed. And even if all of the teeth are to be radiographed, those which respond to the electric test need not be radiographed or studied with such care as those which cannot be tested or test neg- ativel}^ Thus the number of negatives it is necessary to make is reduced and at the same time the operator's at- CLINICAL VALUE OF THE TEST 97 tention is directed to tliose parts where make-overs are most likely to be indicated. It is always tlie part of wisdom to avoid unnecessary x-ray exposure, and in some emergency cases where the operator hajipens to be operating Avith inadequate pro- tection this is especially true. Much has been said of x-ray pictures relieving the den- tal operator of the necessity of working in the dark. The electric test relieves the x-ray operator himself from the handicap of working in the dark and so enables him to make a better examination. In cases of systemic disease examination of the mouth for infection is made in one of three Avays : (1) All teeth and all parts of the mouth are radiographed. (2) All teeth which do not react positively to the electric test, or cannot be tested, all regions from which teeth are miss- ing, and all teeth affected, or thought to be affected, with pyorrhea and all regions of unusual appearance are radio- graphed. (3) The teeth which react negatively and those which cannot be tested are radiographed. For the reasons already given, the writer applies the electric test even if all the teeth are to be radiographed and whether it is permissible to eliminate parts of the mouth from the necessity of examination at all or not de- pends on two things: The operator's judgment and the electric test. When the examination is for iDulpless and abscessed teeth only, those regions in which the teeth respond per- fectly and positively to the test need not be radiographed. When the examination is more inclusive, such regions may be radiographed and may reveal such lesions as ca- rious cavities, overhanging fillings, incipient iiyorrhea, odontomata, and supernumerary teeth. Where we speak of the application of the test Ave as- sume that its api^lication is made in a competent, intelli- 98 ELECTRO-RADIOGRAPHIC DIAGNOSIS gent manner, for nnless this is the case, the electric test, like all tests under similar circumstances, is useless. 2. Where No X-Ray Machine Is Available Where no x-ray machine is available the only way to determine which teeth are pulpless with any degree of accuracy is to use the electric test. This will, in most cases, enable the operator to locate the pulpless teeth quite successfully. A friend who ''believes in the ex- traction of all pulpless teeth" maintains that the deter- mination of which teeth are pulpless is all that is neces- sary and that if this can be done with the electric test then radiographs are unnecessary. He fails to consider the value of the radiograph to verify his electric test find- ings and, further, the radiograph, by showing the amount of bone destruction, assists in curettement, so it helps even the extreme extractionist. It is necessary to remove shell crowns before the teeth carrying them can be tested. Where we have the combination of a seriously sick pa- tient and no x-ray machine available, the test may be used to locate the pulpless teeth. Thus extraction of teeth with vital pulps may be avoided and at the same time all peri- apical infection is eliminated. 3. To Check All X-Ray Findings Both the electric test and the radiograph are quite sus- ceptible to error — to misinterpretation let us say — but taken together, letting the one check the other, chance for error, if not entirely eliminated, is reduced to an agree- able minimum. The writer started to use the electric test in his practice of radiodontia in selected cases and came gradually to use it in all cases. It is my practice now to apply the test first, in all cases where radiographs are to be made, and to make records of the results of the application of the CLINICAL VALUE OF THE TEST 99 test on the chart innstratecl in Fig. 22. From the records on the electric test chart, the recorded history of the case, and the finislied, mounted radiographic negatives, a diag- nosis and prognosis are given. In cases where a tooth is suspected of being pulpless or abscessed and an x-ray examination is to be made of such a tooth I make it an invariable rule to test at least the two teeth approximating the one under examination. 4. To Find Teeth with Dead Pulps Which Could Not be Found by Any Other Means A tooth Avitli (as yet) no periapical bone change, or filling material in the pulp chamber or canals that has a dead iduIjd cannot be located by means of radiographs. Such teeth may be found by the use of the electric test. When the symptoms (there may or may not be symptoms) are such as to place a certain tooth under suspicion the electric test ivill assist in diagnosis. 5. To Find Abcesses Which Might Otherwise be Over- looked Because They Fail to Show in Radiographs Made at Certain Angles Let us consider a hypothetic case, the like of which is frequently met. A radiograph is made of a certain tooth. It shows no abscess and no canal filling, but the electric test for this tooth is negative. Also jDerhaps there are abscess symptoms, a fistula in the vicinity. Another ra- diograph is made at a different angle and shows osteo- clasia. Thus an abscess cavity is found which, had it not been known that the tooth did not have a vital pulp, would have been overlooked. Foreshortening of the upj^er teeth may result in the failure of an existing abscess cavity to show. Slight elongation is sometimes advantageous; it enables the operator to see abscess cavities which might otherwise be overlooked. 100 ELECTKO-RADIOGRAPHIC DIAGNOSIS 6. To Assist in Recognizing Slight Osteoclasia An area of osteoclasia may be so small that one is un- able to say definitely whether it is really osteoclasia or not. In such cases, whether the pnlp is vital or not may be the deciding factor. If the pnlp is vital, of course the suspicious area is not a bone change due to infection, but if the pulp is not vital, a suspicious area can be classed as osteoclasia due to infection, especially if there is some osteosclerosis also. 7. To Avoid Mistakes When the End of a Root and An Abscess Cavity (With No Connection Between the Two) Overlap in the Radiograph Due to the Angle at Which the Exposure Is Made When a tooth seems to be involved in an abscess, but responds to the electric test, it is sometimes possible to make radiographs at different angles which will show that, after all, the suspected tooth is not involved in the abscess cavity. If a root end is more or less surrounded by an abscess cavity it will register in radiographs, if at all, at the end of the affected tooth. But if the abscess cavity is at the side of the root, and the root end only ap- pears to be involved in the abscess due to the angle of the x-rays, a shadow of the abscess cavity can usually be cast on the film aw^ay from the root end. The electric test thus indicates the expediency of mak- ing more radiographs at different angles in such cases and keeps the operator from accepting false radiographic evidence. See Figs. 69 and 70. Abscesses arising from the lingual roots of upper bi- cuspids not infrequently have the radiographic appear- ance of involving the cuspid and lateral incisor. This ap- pearance of involvement in the radiograph may be due to actual lapping of the abscess cavity to the lingual of the cuspid or lateral or may be due to the angle at which the exposure is made. CLINICAL VALUE OF THE TEST 101 8. To Avoid Misinterpretation When the Abscess Cavity Laps to the Lingual or Facial of the Adjacent Teeth It is possible for an abscess cavity to lap to the lingual or facial of the roots of the adjacent teeth in such man- ner that healthy teeth have the appearance of being in- volved in the abscess. In such cases the electric test is often the deciding factor and so of the utmost importance. This lapping of an abscess cavity is most likely to oc- cur to the lingual in the upper teeth. Cysts, as well as abscesses, may lap to the lingual or facial of healthy, un- involved teeth. 9. To Differentiate Between the Mental Foramen and an Abscess Cavity The fact that the mental foramen may have the appear- ance of being an abscess of the first or second (usually second) lower bicuspid has become common knowledge. Such common knowledge in fact that the writer has seen an abscess cavity mistaken for the mental foramen! Where the electric test can be applied and is positive, the operator may know that a radiolucent area at the apex of a lower bicuspid is the mental foramen. Where the response to the test is negative, the operator should look elsewhere in his radiograph to locate the mental foramen. It is sometimes best to make an extraoral radiograiDh for this purpose. Where the result of the electric test is definitely positive all doul^t is immediately and completely removed. 10. To Differentiate Between the Anterior Palatine, or Incisive, Foramen and an Abscess Cavity As with the mental foramen, the fact tluit the palatine foramen may be mistaken for an abscess is becoming so well known that there is danger of abscesses beine: mis- 102 ELECTRO-RADIOGRAPHIC DIAGNOSIS taken for the anterior palatine foramen. And, as in the case of the mental foramen the electric test, Avlien posi- tive, enables the operator to make a prompt and accurate diagnosis. When the test is negative an intraoral radiograph may be made in such manner as to cast the shadow of the palatine foramen between the roots of the central in- cisors, instead of the apex of the root of one of them. I have mentioned it before but it is of sufficient im- portance to justify repetition : When a radiolucent area can he cast aivay from the end of the root, it is not an abscess involving the end of the root. 11. To Differentiate between the Antrum of Highmore and an Abscess Cavity One familiar v/itli the appearance of intraoral dental radiographs does not often have a great deal of difficulty in distinguishing the difference between the antrum of Highmore and an abscess cavity, but one less skilled in interpretation often has a great deal of difficulty in this respect. And even one skilled in interpretation will feel much more secure in the accuracy of his opinion if he verifies it by applying the electric test and finds that the pulps of the bicuspids and molars are vital. Some points of difference between the radiographic appearance of the antrum of Highmore and an abscess cavity are: Of course abscess cavities are usually not nearly so big as the antrum, but a small antrum may be much smaller than a very large abscess. The outline of the antrum is more symmetrical, less jagged, than the out- line of an abscess cavity, as a rule. Also the outline of the antrum is rimmed Avith a thin radiopaque line, represent- ing the walls of the antrum. CLINICAL VALUE OF THE TEST 103 12. To Differentiate between the Somewhat Radiolucent Area Which Sometimes Appears in the Apical Regfion of Upper Lateral Incisors, Due to the Canine, or Incisal Fossae, and Radio- lucence Caused by Infection and Patholo^c Bone Change This seems to the writer to require no special explana- tion. As always the value of the electric test hinges on the fact that a tooth with a vital pulp cannot he ab- scessed. 13. To Differentiate Between Nostril Spots and Abscesses Like other things which cause radiolucent areas at the apices of the roots of teeth without actual involvement of the ends of the roots of the teeth, a nostril spot may be cast away from the end of the root by changing the angle of the x-rays. 14. To Aid in the Recog-nition of Nasal Fossse Spots as Such Nasal fossEe spots are so characteristic in appearance that it is only occasionally tliat one is found which really resembles an abscess cavity. Dr. Noboru Teruuchi points out the fact that bilateral abscesses of similar size and shape, arising from the apices of the roots of the laterals, or centrals, might be mistaken for nasal fossse spots. 15. To Aid in the Recognition of the Inferior Dental Canal as Such The inferior dental canal is characteristic in appear- ance to the operator familiar with radiographs, but may be mistaken for a pathologic lesion by one less familiar with the apiDearance of dental radiographs. A positive reaction from the application of the electric test would relieve uncertainty in some cases. 104 ELECTRO-EADIOGEAPHIC DIAGNOSIS 16. To Differentiate Between a Very Small Abscess Cavity and an Unusually Large Periapical Space By periapical space the writer does not mean either an air space or a vacnnm, but a space between the root end and the bone; a space doubtless filled with vascular tissue. In the past there has been some discussion as to whether such spaces exist. I have seen them, and they resemble a small abscess cavity. One cannot confuse a large periapical space with a small abscess if the electric test is applied and the pulp found vital. As further aids in differential diagnosis I may say that osteosclerosis is likely to occur in case of the abscess and that the lamina dura can probably be seen unbroken in the case of the large periapical space. 17. To Differentiate Between a Cancellous Spot of Un- usual Appearance and an Abscess Cavity In some cases the cancellous openings in the bone are abnormally large and I have seen them mistaken for ab- scesses. Such a mistake could not occur if the electric test were applied and the pulps of the suspected teeth found vital. 18. To Assist in Differentiation Between Pathologic Con- ditions and Physiologic Conditions about the Buccal Roots of Upper Molars When the parts are in a state of perfect health there are nevertheless sometimes radiolucent areas at the apices of the buccal roots of the upper molars. Also the disto- buccal root of the uioper molar is so small that it some- times fails to show clearly in radiographs and leads the uninitiated to believe that there is root absorption. When the fact that the pulp in the tooth is vital can be estab- lished by the application of the electric test uncertainty in x-ray interpretation can be eliminated. CLINICAL VALUE OF THE TEST 105 19. To Assist in Differentiation between Absorbed, Roughened Root and a Radiograph Made with the Rays Directed through the Tooth Diag- onally from Facial to Lingual When a radiograph of the upper bicuspids is made with the rays passing diagonally through the teeth, the roots of the teeth in the radiograph not infrequently have a fuzzy, indistinct appearance. I have seen this appear- ance of the root mistaken for absorption of the root. Since the roots of vital teeth do not absorb, except in the most extraordinary cases, or in cases of pressure from un- erupted tooth bodies, the establishment of the fact that the pulps are vital by means of the electric test elimi- nates all except the remotest possibility of root absorp- tion. In the case of the upper bicuspids the small roots some- times fail to show distinctly and so may seem to be ab- sorbed, like the distobuccal roots of upper molars. 20. To Differentiate between Partially Formed Root and an Abscess If the fact that the pulp is vital can be established by means of the electric test, this mistake cannot occur. It is less likely to occur with the dentist who will take into account the age of the patient. 21. To Determine How Many Teeth Are Involved in an Abscess The writer recalls the first very large abscess he en- countered in which five teeth were involved. By check- ing up the x-ray findings with the electric test and find- ing that those teeth Avhicli seemed to be abscessed did not respond to the electric test I felt much more certain of my diagnosis than I could have otherwise. 106 ELECTEO-RADIOGRAPHIC DIAGNOSIS 22. To Assist in Differentiation between Dentoalveolar Abscess and Peridontoclasia (Pyorrhea) When serumal calculus on the roots of a tooth causes irritation, which in turn produces inflammation, and which in its turn results in suppuration, and the pus hap- pens to penetrate the external alveolar plate, instead of following along the side of the root and discharging at the neck of the tooth, the clinical picture is almost identi- cal with that of an ahscess. But if the electric test shows that the tooth under suspicion of being abscessed has a vital pulp then the seat of the suppurative process may be looked for along the side of the root instead of at the apex. THE TEST AS AN AID IN THE INTERPEETATION OF RADIOGRAPHS CHAPTER XI THE TEST AS AN AID IN THE INTERPRETATION OF RADIOGRAPHS The style of presenting the evidence set forth in this chapter is not formal, but, I hope, it is convenient and practical. The cases illustrated are arranged somewhat in the order of the classes of cases enumerated in Chap- ter X. Due allowances must be made for the loss of detail in halftones as compared to original negatives. Where definite statements are made regarding findings it is to be understood that subsequent treatment and his- tory verified the diagnoses. I shall, throughout this chapter, occasionally use an illustration which I cannot interpret. The reason I can- not make an interpretation is that I do not have electric tests to guide me and the reason for using the illustration without giving a diagnosis of the case is to show the reader how heavily I lean on electric pulp test findings. Fig. 43. Failure of the lower first bicuspid to respond normally to the electric test directed attention to the tooth. The radiograph shows evidence of a large abscess cavity. There were no local symptoms or signs at all. Had the electric test not been used a radiograph would not have been made of this tooth and the area of infection would not have been found. On the enamel of the lower first bicuspid the electric test was definitely negative. On the metal of the occlusal filling it was very faintly posi- tive. Normally it should have been positive (+) on enamel and positive very strong (+VS) on the metal filling. Hence I have said that the tooth did not respond nor- mally to the test, even though a faint positive was ob- tained on the simple occlusal filling. 108 INTERPRETATION OF RADIOGRAPHS 109 Fig. 43. Fig. 44. Fig. 44. If one were making a casual examination of the mouth to determine which teeth were ''suspicious" and should therefore be radiographed, it is unlikely that the little filling in the upper lateral incisor would arouse suspicion of a dead pulp. But when the electric test is used and the lateral fails to respond, suspicion is aroused. The radiograph shows the lateral incisor abscessed. 110 ELECTRO-EADIOGRAPHIC DIAGNOSIS Fig. 45. Tlie abcessed lower lateral was located by means of tlie electric test. The symptoms were sucli — there was a fistula — that it Avas known that one or more of the six anterior teeth w^ere abscessed. Just which one was determined by the use of the electric test. The test finding was verified by the radiograph. Also the radio- graph shows the extent of the loss of osseous tissue. In the absence of an x-ray machine the offending tooth would have been located by the test unaided by radio- graphs. No cavity in the abscessed tooth. Fig. 46. History of this case when it presented was that "an abscessed lower lateral incisor has been ex- tracted a month previously. Pus still discharging from the socket of the extracted tooth. ' ' The electric test was applied to the central incisor and cuspid approximating the socket of the extracted tooth. The central incisor responded positive (+) the cuspid negative (-). Thus a diagnosis was made readily enough before the radiograph was made. The radiograph verifies the diagnosis, show- ing the fistulous tract of the abscess arising at the apex of the cuspid and passing over into the socket of the ex- tracted lateral incisor. INTERPRETATION" OF RADIOGRAPHS 111 Fig. 4S. Fig. 46. 112 ELECTRO-RADIOGRAPHIG DIAGNOSIS Fig. 47. Three blind abscesses at the apices of the up- per incisors. The fact that the pulps were dead in these teeth could have been established by the use of the electric test. The radiograph was necessary to show the amount of bone destruction. The teeth have artificial enamel fill- ings in them. I am told that the first silicious cements placed on the market contained some ingredient which devitalized pulps. I cannot vouch for the truth of this. Absolutely all I know about the matter is this: I have found a sufficient number of dead pulps in teeth, with ar- tificial enamel in them, so that I am particularly careful to test such teeth for pulp vitality. More of this material is being used alll;he time but I do not notice any increase in pulp death in teeth filled with it which would seem to indicate that the silicious cements now in use do not con- tain a pulp devitalizing ingredient. (Radiograph by Al- ger of Los Angeles.) Figs. 48 and 49. These two radiographs illustrate the necessity of checking up x-ray findings. In Fig. 48 the abscess arising from the lower cusj)id seems to involve the adjoining lateral incisor and perhaps the central in- cisor also. But the electric test for pulp vitality indi- cates that the pulps in the incisors are vital and there- fore not involved in the abscess. In Fig. 49 the central incisor looks as though it might be involved in the abscess of the lateral incisor though its appearance is no more suspicious than the lower incisors, particularly the lateral, in Fig. 48. The fact that the upper central is negative to the electric test while the lower incisors are positive, is what tells us that the upper incisor is abscessed and that the lower incisors are not. INTERPRETATION OF RADIOGRAPHS Fiff. 47. Fig. 48. Fig. 49. 114 ELECTRO-RADIOGEAPHIC DIAGNOSIS Figs. 50 and 51. Fig, 50 is a postoperative radiograph made following the root resection of the upper first bi- cuspid. The film just takes in the apex of the lateral in- cisor. It looked "suspicions" and was tested. Result negative (-). Another radiograph (Fig. 51) was made. The slight area of osteoclasia can be seen quite clearly. The pulp of the lateral was dead and the tooth abscessed. Fig. 52. In this radiograph the upper third molar is missing and the shadow of the malar bone falls over the first molar, the one on the reader's left. There is a very suspicious radiolucent area above the apex of the second molar. But the second molar responds so perfectly to the electric test that we are safe in saying that the pulp is vital and that the radiolucent area is not an abscess. Fig. 53. We have seen the necessity of checking up x-ray findings with the electric test. Now let me illus- trate the necessity of checking up pulp test findings with radiographs. The u|)per cuspid was quite definitely nega- tive to the strongest current. The radiograph shows the reason for it; the pulp has receded away above the gum line. The pulp is vital but the current could not pene- trate the secondary dentin to the pulp. Fig. 54. The lower cuspid responded positive but very weak (+VA¥). The reason it responds so weakly to the electric test is seen in the radiograph, i.e., the large pulp stone. The first molar is abscessed. Considerable peri- dontoclasia about the cuspid. INTERPRETATION OF RADIOGRAPHS 115 Fig. 50. Fig. 51. Fig. 52. Fig. 53 Fig. 54. 116 ELECTRO-EADIOGEAPHIC DIAGjSTOSIS Fig. 55. This radiograpli illustrates the expediency of the rule to test the teeth on either side of the one sus- pected of being abscessed. A fistula pointed just to the distal of the apex of the root of the second bicuspid and so it was susjDected of being an abscessed tooth. The radiograpli shows a definite radiolucent area just to the distal of the apex of the second bicuspid, and involving its apex. But the results of the application of the test were as follows: Second bicusj)id joositiye (+), first molar positive (+), first bicuspid negative (-). A close study of the radiograph with the tests as a guide resulted in observa- tion of a fistulous tract leading from the first bicuspid to the radiolucent spot in the apical region of the second bi- cuspid. (Radiograph by Alger of Los Angeles.) Figs. 56, 57, and 58. Figs. 56 and 57 were made at the same sitting. They show the apex and periapical tissues of the upper lateral incisor at Avidely different angles. Neither of them show any bone change which might be taken as evidence of a septic pulp in the lateral. The lateral did not resj^ond to the electric test for pulp vitality though, and the operator who referred the case was ad- vised to make a diagnostic opening into the lateral in- cisor. The ojDerator pinned his faith in the aj)pearance of radiographs and did not make a diagnostic opening. Fig. 58 was made seven months later. We now see quite definite bone destruction above the aj^ex of the lateral incisor. liSTTEEPRETATIOX OF RADIOGRAPHS 117 Fig. 55. Fig. 56. Fig. 57. Fig. 58. 118 ELECTRO-RADIOGEAPHIC DIAGlirOSIS Figs. 59, 60, and 61. These three illustrations have been made experimentally from a skull. Fig. 59 does not show the apical bone destruction, while Figs. 60 and 61, made at different angles, do. Suppose we should have a radiograph of a tooth like the second bicuspid in Fig. 59. There would be nothing in such a radiograph to warn us sufficiently of the necessity of making the radiograph over at different angles, unless we had records of the ap- plication of the electric test. Fig. 62. Another view of the parts in which the angle at which exposure was made was correct. No distortion of the image and the abscess shows. Figs. 63 and 64. When Ave have reason to believe a tooth is pulpless, or we know it as we do in the case of the shell crowned upper molar because we can see some canal filling, then we are fully aware of the necessity of getting a good radiographic view of the tooth. But if we have no idea whether the pulp is vital or not then we do not know exactly how thorough our radiographic exam- ination should be. Fig. 63 fails to show the abscess of the upper molar, while Fig. 64, the last one made, shows it, or, to be meticulous, it shows a radiolucent area which I take to be an abscess cavity. It is not infre- quently necessary to deliberately distort upper molars in order to cast the shadow of the mesiobuccal or disto- buccal roots far enough mesially or distally to observe the tissues at their apices. INTERPRETATION OF RADIOGRAPHS 119 Fig. 59. Fig. 60. Fig. 61. Fig. 62. Fig. 63. Fig. 64. 120 ELECTRO-EADIOGEAPHIC DIAGNOSIS Fig. 65. Pericementitis of the second molar. Tootli carries very large amalgam filling. Electric test positive weak (+W). Tootli more tender to pressure to the distal than to mesial or mesio-vertical pressure. The radio- graph shows the reason for the pericementitis. The filling in the distal of the second molar and the filling in the mesial of the third molar both hang into the interproxi- mal space causing irritation, inflammation, and osteo- clasia. Fig. 66. The radiolucent spots at the apices of the cuspid and the second bicuspid are of about the same size and almost the same general appearance. The spot at the apex of the second bicuspid I believe to be osteoclasia and odontoclasia, due to infection, in short a spot due to a pathologic process, while the spot at the apex of the cuspid is plw siologic ; that is to say, it does not represent disease. The fact that the cuspid responds positively (+) to the electric test is very strong, I might almost say con- clusive, evidence of the correctness of the opinion regard- ing the cuspid. Also there is a small "suspicious spot" in the apical region of the first bicuspid, but the tooth responds posi- tively (+) to the electric test and so I do not look upon this area as a spot of infection. Fig. 67. The small radiolucent spot at the apex of the root of the second bicuspid might be looked upon as evi- dence of infection if it were not for the fact that this tooth has a vital pulp, Avhieh fact has been established by its very definitely positive (+S) response to the electric test for pulp vitality. A gold shell crown has been re- moved to test this tooth, a procedure which is not infre- quently indicated. INTERPRETATION OF RADIOGRAPHS 121 *^B| lA iM [1 Fig. 65. Fig. 66. Fig. 67. 122 ELECTRO-KADIOGRAPHIC DIAGNOSIS Fig. 68. I do not have pulp testing records of this case. Therefore I cannot say whether the small radiolucent areas at the apices of the lower central incisors repre- sent areas of infection or not. The fact that one of them seems to be broken off is contributory evidence of abscess. Bnt, I would not wish to give a final opinion without re- course to the electric test for pulp vitality. Figs. 69 and 70. These two radiographs are of the same case. They are reproduced here (by courtesy of the publishers of my book "Elementary and Dental Radi- ography") because it was this case which first impressed me wdtli the extreme value of the electric test, and caused me to have test record sheets printed and make it routine practice to apply the test in practically all radiodontic cases. The following history of the case is quoted from "Ele- mentary and Dental Radiography": "The end of the root of an upper lateral was resected to cure an abscess. The wound made at the time of opera- tion did not heal normally, A radiograph was made (Fig. 69) . It seems to show that the central is involved in the lateral's abscess cavity. The central was tested for vital- ity of its pulp. It responded to the electric test, indicat- ing a vital pulp. Another radiograph was made, Fig. 70. 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 does not show clearly. The cuspid was tested and its pulp did not respond to the application of the current. It was opened and found to contain a putrescent pulp. Neither the central incisor, at first suspected, nor the cuspid, finally opened, had carious cav- ities in their crowns. INTERPRETATION OF RADIOGRAPHS 123 Fig. 68. Fig. 69. ^■^^ ^^ ^^^i^^^^B I . ^ '■ ^^ 1 Fig. 70. 124 ELECTRO-RADIOGRAPHIC DIAGNOSIS Figs. 71 and 72. I do not have the electric test records for this case and I cannot therefore give a reliable inter- pretation of the radiographs. I see by Fig. 72 that the central incisor has been opened, but whether the operator found a vital or a septic pulp I cannot tell from the radio- graph. My guess from observation of Fig. 71 is that the cuspid harbors a vital pulp, but I would not want to give a final opinion without the electric test to help me. (Ra- diographs by McCormick.) Fig. 73. The radiolucent area at the apex of the cuspid gives the tooth the appearance of being abscessed, but it is not. It responds positively to the electric test. The abscess arises from the lingual root of the first bicuspid, the crowned tooth. Fig. 74. The appearance of this radiograph is such as to direct suspicion to the lateral incisor and cuspid. There is considerable bone destruction between these two teeth, and the area of radiolucence extends slightly beyond the apex of the lateral incisor. But both of these teeth — the lateral and cuspid — respond positively (+) to the electric test; so does the central incisor. But the first bicuspid responds negatively (-). The pulp in the first bicuspid was found devitalized and septic. The abscess — i.e., source of bone destruction — was from the lingual root of the first bicuspid. Figs. 75 and 76. Different views of the same case. Both the lateral incisor and the first bicuspid are involved in a very large abscess. And, certainly, the cuspid has the radiographic appearance of being involved also — but it is not. It responded (+) to the electric test. Subse- quent history proved correctness of diagnosis. It will probably not show in the halftone, but, in the negative, a radiolucent line (the usual line indicating the pericemental membrane) could be seen following the cus- pid root. The presence of this line could not be con- INTEKPRETATION OF EADIOGKAPHS 125 Fis. 71. Fig. 73. Fig. 74. Fig. 75. Fig. "i^i. 126 ELECTRO-EADIOGEAPHIC DIAGiSTOSIS sidered proof of the vitality of tlie tooth, but it was con- tributory evidence of vitality. Not even the presence of both the radiolncent line, indicating the pericemental membrane, and the radiopaque line, indicating the lamina dura (i.e., the dense layer of bone lining tooth sockets) proves the pulp of the tooth vital and the tooth not ab- scessed. (See Fig. 59.) Fig. 77. The radiographic appearance of the lateral incisor in this illustration is quite similar to that of the cuspid in Figs. 75 and 76. Yet, in this case, the lateral is involved in the abscess, while the cuspid, in Figs. 75 and 76, is not. It is the electric test for jDulp vitality that gives us the information necessary to the correct inter- pretation of the radiographs in these cases. Fig. 78. This illustration is similar in appearance to Figs. 75 and 76. I regret that I cannot locate my records for this case. My recollection is that the cuspid re- sponded positive (+) to the test and was not involved in the large abscess. Figs. 79, 80, 81, and 82. Showing variation in the loca- tion of the mental foramen. Fig. 79. The mental foramen considerably below the apices of the roots and midway between the first and sec- ond bicuspid. Fig. 80. The mental foramen above the apices of the roots just to the mesial of the second bicuspid. Fig. 81. The mental foramen at the apex of the root of the second bicuspid. Similar in appearance to an abscess area, but a positive (+) reaction to the electric test elimi- nates the possibility of abscess. Fig. 82. The mental foramen at the apex of the first bicuspid. This is a little farther forward than one ordina- rily finds the foramen and so the test is particularly needed to make sure that the pulp in the first bicuspid is vital. INTERPRETATIO:?^ OF RADIOGRAPHS 12- Fig. 77. Fig. 78. Fig. 79. Fig. 81. Fig. 82. 128 ELECTRO-RADIOGEAPHIC DIAGNOSIS Fig. 83. When in doubt, it is sometimes expedient to make an extraoral radiograph to assist in differentiation between an abscess and the mental foramen. If a spot is seen at the apex of one of the bicuspid teeth and the men- tal foramen can be seen elsewhere, then the spot at the apex of the tooth must be an abscess — or a large cancel- lous spot in the bone. And one can get a fair idea as to whether it is a large cancellous spot or not, by the general appearance of the bone, a considerable area of which can be seen in an extraoral radiograph. In this illustration the mental foramen is at the apex of the second bicuspid. IISTTERPRETATION OF RADIOGRAPHS 129 Fig. 83. 130 ELECTRO-EADIOGKAPHIC DIAGNOSIS Fig. 8-t. Abscess at apex of first bicuspid. Opinion verified by fact that tooth tests negative (-) . Fig. 85. Abscessed lower bicuspid. The radiolucent area might easily have been mistaken for the mental fora- men, particularly because the tooth has no carious cavity in it. Its response to the electric test was negative, how- ever, which led to the correct interpretation of the radio- graph. Fig. 86. That the radiolucent area at the apex of the second bicuspid is of pathologic origin, and not the mental foramen, is indicated rather conclusively b^^ the fact that the tooth resjDonds negative (-) to the electric test. The radiolucent area in this case has more the appearance of an abscess; it is too large for a normal mental foramen. The tooth has no cavitv in it. INTERPRETATION OF RADIOGRAPHS 131 Fig. 84. Fig. 85. Fig. 86. 132 ELECTRO-EADIOGRAPHIC DIAGNOSIS Fig. 87. A photograph of a skull showing the anterior palatine foramen, also called the incisive foramen. Fig. 88. The large radiolncent area and the short root of the central incisor would lead the unwary and the non- user of the electric test to suspect that we have here a dentoalveolar abscess exhibiting considerable tissue de- struction both osseous and dental. The facts are that the radiolncent area is the anterior palatine foramen and the root of the tooth is malformed and short, not absorbed. The radiograph is of the dry specimen shown in Fig. 87, in which the shadow of the anterior palatine foramen has deliberately been cast at the apex of one of the central incisors giving it (the foramen) the appearance of an ab- scess area. In order to cast the shadow of the foramen at the apex of the central incisor tooth, the horizontal angle of the x-ray was somewhat as indicated in Fig. 87 by ar- row No 1. Fig. 89. Another radiograph of Fig. 87, which like Fig. 88, shows the anterior palatine foramen at the apex of the central incisor. Figs. 90 and 91. Two radiographs made at different angles from Figs. 88 and 89, in Avhich the shadow of the anterior palatine foramen is cast between the roots of the central incisors instead of at the apex of one of them. The horizontal angle to make these radiographs was more like No. 2 than arrow No. 1 of Fig. 87. The combination of central and lateral incisors on one intraoral radiograph is a good combination to get a good view of the parts, but the operator should be rather care- ful to have his horizontal angle as indicated by arrow No. 2 and not as indicated by arrow No. 1 else the anterior palatine foramen may be mistaken for an abscess. This is especially true when the central incisors are known to be pulpless. INTEEPEETATION OF RADIOGRAPHS 13- Fig. 87. Fig. 88. Fig. 89. Fig. 90. Fig. 91. 134 ELECTRO-EADIOGRAPHIC DIAGNOSIS Figs. 92 and 93. In Fig. 92 a radiolucent area is seen at the apex of the central incisor, with the large inlay in it, having the ajDpearance of an abscess. The tooth re- sponds positively (+) to the electric test, however, which indicates that the pnliD of the central is vital and there- fore that the radiolucent spot at its apex is the incisive foramen and not an abscess cavity. Fig. 93 is another radiograph of the same case as Fig. 92, made at a different angle. The shadow of the anterior palatine foramen is no longer seen at the apex of the central incisor with the large inlay. It can be seen faintly between the apices- of the central incisors. Figs. 94 and 95. Two radiographs of the same case which, like Figs. 92 and 93, show the anterior palatine foramen at the apex of a central incisor from one view (Fig. 94) and between the apices of the roots of the in- cisors from another view (Fig. 95). Fig. 96. A colleague sends me this radiograph and as- sures me that there are no symptoms or signs of cyst and that the pulp of the central incisor is vital. Accepting this information as true, I should say we have here a very large and most unusual-appearing anterior palatine fora- men. Fig. 97. Another anterior palatine foramen of some- what unusual appearance. IXTEKPRETATIOX OF RADIOGRAPHS yjLJ 135 Fie. 92. Fie. 9A Fig. 55. Fig. 96. Fig. &/. 136 ELECTKO-EADIOGPvAPHIC DIAGNOSIS Figs. 98 and 99. Dr. Mathew Cryer, long before the nse of x-rays became popular, wrote a genuine master- piece of a book entitled ''Internal Anatomy of the Face." It was this little book that first taught us of the tremen- dous variability of the antrum of Highmore in size, shape, and location. The use of radiographs have fully borne out Dr. Cryer's teaching. Figs. 98 and 99 are the right and left side of the same case and show a very large antrum of Highmore. In cases such as this it is a relief to be able to test the teeth with the electric test and find them vital. It verifies one's opinion. In this particular case the crowned teeth could not be tested, but all the other teeth were tested and re- sponded (+). Compare Figs. 98 and 99 with Fig. 126. Figs. 100 and 101. Two radiographs of the same case, made at slightly different angles. Compare the antrum in this case to the ones shown in Figs. 98 and 99. This one has very much the appearance of an abscess cavity arising from the second bicuspid or first molar. Both bicuspids and both molars test positively (+) how- ever. The second molar responds positive strong (+S). The reason for it is the carious cavity in the distal sur- face. Figs. 102 and 103. Two cases in which the first molars responded negative (-) to the electric test. Both had septic pulps. Fig. 102 shows evidence of cyst formation. The radiographic evidence of infection in these cases might easil}^ have been overlooked — i.e., mistaken for antrum shadows — ^had it not been for the electric test which directed especial attention to them. HSrTERPRETATION OF RADIOGRAPHS 137 Fig. Fig. 99. Fig. 100. Fig. 101. Fig. 102. Fig. lOo 138 ELECTRO-EADIOGEAPHIC DIAGNOSIS Figs. 104 and 105. The two sides of the same case showing antra of more or less typical appearance. Figs. 106 and 107. Fig. 106 exhibits a shadow over the cnspid and first bicuspid which might, from the radio- graphic ai^pearance, be mistaken for an abscess or cyst. Both the first bicuspid and the cuspid res^Dond positive (+) to the electric test. The shadow at their apices is the maxillary sinus. Fig. 107 is another case in which the antrum is seen so far forward it overlaps (in the radio- graph) the end of the root of the cuspid. Figs. 108 and 109. Right and left sides of the same case. Another case in which the shadow of the antrum comes rather far forward. The radiopaque lines indicating the walls — i.e., the dense cortical bone — surrounding the an- trum can be seen rather clearly in this case. The opinion that the large radiolucent areas are the maxillary sinuses is strengthened by the results of the application of the electric test. All teeth test positive (+), except the lateral incisors. The dark area in the region of the left lateral (Fig. 108) is of infectious origin. IXTEIVPItETATlOX OF EADIOGEAPHS 139 Fig. 104. Fig. 105. Fi.s;. 106. Fig. 107. Fig. 108. Fig. 109. 140 ELECTRO -RADIOGRAPHIC DIAGIiTOSIS Fig. 110. This radiograph illustrates a rather typical appearance of radiolucency in the apical region of the upper lateral incisor, due to the canine or incisal fossae, a depression just mesially to the canine eminence. In passing, note the recession of the pulp — the throw- ing U13 of secondary dentin as it retreats — caused by the carious cavity in the tooth. Figs. Ill and 112. In this case the radiolucency in the apical region of the lateral incisor is too pronounced to be considered physiologic. Yet the lateral responds positive (+) to the electric test. So do the approximating central incisor and cuspid. The cause of the radiolucency, in the region of the apex of the lateral, which by the way can be seen extending over toward the cuspid, arises from the badly diseased first bicuspid. Fig. 113. Radiolucency in the apical area of the lateral on the reader's left. Tooth negative (-) to electric test. Tooth abscessed. The radiolucent area due to the abscess and the nasal fossa spot on that side merge into one an- other. Figs. 114 and 115. The f ossa3 spots can usually, but not always, be seen in radiographs of the upper incisor teeth. Other things being equal, the higher the angle of the x-rays at the time of exposure, the lower down — i.e., closer to the apices of the roots of the upper incisor teeth — fall the shadows of the nasal fossae. The nasal fossae spots in Fig. 114 are removed a con- siderable distance from the apices of the roots of the in- cisor teeth, while in Fig. 115 the nasal fossae spots are just above the apices of the incisors. This difference is due partly to differences in the cases and partly to differ- ences in the angle. Fig. 114 is more typical in appear- ance than Fig. 115. IlSrTERPRETATION OF RADIOGRAPHS 141 Fig. 110. Fig. 111. Fig. 112. Fig. 113. Fig. 114. Fig. ILS. 142 ELECTRO-EADIOGRAPHIC DIAGNOSIS Fig. 116. Another case in Avliicli tlie nasal fossse spots are ratlier low down and in wliicli tlie shadow of the ah- scess of the central incisor, on the reader's left merges into the shadow of the nasal fossae. Fig. 117. The disto-hnccal root of the npper first molar seems to be absorbed but the tooth is vital — responds positive (+) to the electric test — and very often the disto- buccal roots of npper molars are not bulky enongli to register in radiographs clearl}^ The spot at the apex of the first bicuspid is of about the same size and appearance as the spot at the apex of the second. However, the first bicuspid responds positive (+) to the electric test. Therefore the spot at its apex cannot be osteoclasia due to infection. Figs. 118 and 119. The same radiograph developed to different degrees of intensity in an effort to show both the roots and the pulp chamber without retouching, or at least with the minimum of retouching. The disto-buccal root of the first molar seems to be absorbed. But we have learned this ma,}^ be ph^^siologic. How about this though ? The tooth responds hardly at all (+VAV) to the electric test! The pulp of the tooth is vital. The reason it does not respond better to the electric test is disclosed by a study of the shape of the pulp chamber. The presence of the large metal restoration in the crown has caused recession of the pulp and development of secondary dentin. The distal half of the pulp chamber is obliterated. INTERPRETATION OF RADIOGRAPHS 143 Fig. 116. Fig. 117. Fig. 118. Fig. 119. 144 ELECTRO-RADIOGRAPHIC DIAGNOSIS Figs. 120 and 121. Radiograplis of the same case made at different angles. Fig. 120 was made with the x-rays passing straight through the teeth from facial to lingual. Fig. 121 was made with the x-rays passing diagonally through the teeth from facial to lingual. Note how in- distinct the root outlines are in Fig. 121. I have seen this indistinctness of root outline due to angle mistaken for absorption of the root due to disease. The roots par- ticularly susceptible to this sort of distortion are : (1) Up- per bicuspids (2) Lower molars (3) Mesio-buccal roots of upper molars. Where the electric test can be applied satisfactorily and a positive reaction is obtained, the appearance of root roughness due to angle cannot be mistaken for absorption of the root. There is a radiolucent area in the mesial sur- face of the first bicuspid which has the appearance of a carious cavity; it is the interproximal space. Figs. 122 and 123. Two radiographs of the same case made at different angles. See how distinct the outlines of the roots of the molar are in one view and how indis- tinct they are in the other. Fig. 124. The radiolucent spots at the apices of the roots of the third molar (the first molar is missing) look very suspicious and they cannot be cast away from the ends of the roots by changing angle. They are at the apices of the roots. The electric test is definitely positive (+). The reason for the small radiolucent areas is that the roots of the teeth are not quite fully formed. Note the funnel shaped open end of the root. (Radiograph by Eller, Albuquerque.) Fig. 125. Same case as Fig. 124, other side of the mouth. INTERPRETATION OF RADIOGRAPHS 145 Fig. 120. Fig. 121. Fig. 122. Fig. 123 Fig. 124. Fig. 12.S. 146 ELECTPvO-RADIOGRAPHIC DIAGNOSIS Fig. 126. The abscess illustrated here is larger than an antrum. Obviously the first bicuspid is pulpless for we see canal filling in the canals. The roots of the cuspid and second bicuspid seem to have their apices absorbed. These teeth gave a negative (-) reaction to the electric test for pulp vitality. After extraction it could be seen that these root ends had been destroyed just as they ap- pear to be in the radiograph. The crown was removed from the lateral incisor and the electric test applied. It was negative (-). This tooth also was involved in the abscess. The central incisor, which does not show in the negative, also was involved as seen in another negative not reproduced here. The electric test is of extreme value in checking up such unusual findings as these. Fig. 127. How many teeth are involved in the abscess illustrated here ! Frankly I cannot tell. I am reasonably sure the central incisor, with the canal filling, is involved because I know it is pulpless and because its apex is about in the mesio-distal center of the diseased area. But are the two approximating teeth involved 1 That is the ques- tion. And, in the absence of electric test records, I can- not answer it. iNTEKPRETATIOlSr OF RADIOGRAPHS 147 Fig. 126. Fig. 127. 148 ELECTRO-EADIOGEAPHIC DIAGISrOSIS Figs. 128 and 129. Two radiograplis from different angles, another case in wliicli I do not have electric test records. Therefore I do not know whether the lateral in- cisor is involved in the abscess or not. I think it is, but I wonld depend on the electric test to verify this opinion. If the tooth has a vital pulp it is not abscessed. If it does not have a vital pnlp, it very likely is abscessed. It is interesting to know that this case was brought to the writer's attention as an example of failure of the root end resection operation to cure a focus of infection — in short as an argument against root resection. It seems to me to be a mighty poor argument against root resection. No wonder we have failure in this case. The cuspid is loulpless and infected, the central also and perhaps the lateral incisor. The operator resected only the buccal root of the first bicuspid. The lingual root, with a very imperfect canal filling in it, remains untouched as can be seen in Fig. 128. The stub of the buccal root is not patched with amalgam. It is not good judgment to draw one's opinion of the possibilities of the root resection operation from cases like this. Fig. 130. Symptoms those of semiacute dentoalveolar abscess with sinus discharging pus in apical region be- tween central and lateral incisors. The radiograph shows bone destruction along the sides of the roots between the central and lateral incisors near the apices but without definitely involving the apices. Resj)onse to electric test a definite positive (+). Conclusion: One of those com- paratively rare cases of "pyorrhea" where, instead of the pus discharging about the neck of the tooth it dis- charges like a dentoalveolar abscess through the external alveolar plate. The treatment indicated for pyorrhea is vastly differ- ent from that indicated for a dentoalveolar abscess. Hence the necessity of correct diagnosis. This case was treated in accord with the diagnosis given above and yielded to the treatment. INTERPRETATION" OF RADIOGRAPHS 149 Fig. 128. Fig. 129. Fig. 130. 150 ELECTRO-RADIOGRAPHIC DIAGNOSIS Fig. 131. Another case in whicli pyorrhea had the symptomatic appearance of a dentoalveolar abscess. But the electric test and the radiograph combined to make a correct diagnosis. The writer has encountered a few cases similar to Figs. 130 and 131, in which the trouble was caused by a silk ligature, or a ring of rubber dam, left on the tooth. The ligature, or rubber ring jerked out of the rubber dam when removed carelessly and hastily, particularly the lat- ter, works beneath the gum toward the root end causing a great deal of inflammation and loosening of the tooth or teeth. The electric test is very valuable in such cases as the symptoms simulate abscess very closely. Orthodontic elastics encircling one or more teeth have been known to escape under the gum and cause the same trouble as- cribed to ligatures and rings of rubber dam. Fig. 132. The third molar responded positive very strong (+VS) to the electric test. The reason is the large carious cavity in the mesial surface. The outlines of the roots are indistinct, not due to angle but to hypercemento- sis. Hypercementosis occurs much more frequently in pulpless teeth than in teetli with vital pulps. Fig. 133. There is a radiolucent spot at the bifurcation of the roots of the lower first molar. The tooth is nega- tive (-) to the electric test. The tooth is abscessed, though there is no radiographic evidence of it at the apices of the roots. The dark area at the bifurcation is caused by a perforation of external alveolar plate, i.e., a hole in the external alveolar plate. This perforation of the external plate of bone on a level with the bifurcation of the roots is due to the tliickness of the oblique ridges. If, my reader, you are inclined to incredulity, let me say I have a dry specimen closely analogous to Fig. 133. INTERPRETATIOlSr OF RADIOGRAPHS 151 Fig. 131. Fig:. 132. Fig. 133. 152 ELECTRO-EADIOGRAPHIC DIAGNOSIS Fig. 134. Note tlie radiolucent area just above the bi- furcation of the roots of the second molar. Tooth re- sponds positive strong (+S) to the electric test. The radiolucent area is a large carious cavity beneath the gum line on the buccal. Fig. 135, The oblique ridges cast a sort of haze over the apical region of lower molars in some cases, so that the operator may overlook an area of radiolucency if he is not careful. Seeing an abscess area through the oblique ridges is rather similar to observing something through a fog. When a lower molar is known to be, or thought to be, without a vital pulp, one is more careful in one's ex- amination of the periapical tissues. Hence the value of the test to determine pulp vitality. Fig. 135 is overdeveloped and published without re- touching. It shows the haze of radiopacity cast by the oblique ridges. In the negative now before me, I can see a radiolucent abscess area, through the haze of the ridges, at the apex of the molar tooth. INTERPKETATIOlSr OF RADIOGRAPHS 153 Fig. 134. Fig. 135. 154 ELECTEO-RADIOGEAPHIC DIAGNOSIS Conclusion My objective in tliis chapter lias been to prove the electric test necessary to the correct and reliable inter- pretation of radiographs and therefore necessary to the art of dental diagnoses. I conld go on indefinitely citing case after case, just as one could go on indefinitely citing case after case to prove the usefulness of the radiograph in the practice of dentistry, but it is not necessary. /' Re- lieve I have attained my objective. I believe I have proved the value of the test and so I submit no further evidence but "let my case rest with the jury." INDEX A Abrasion, 78 Abscess (also see differentiation), 108, 109, 110 cavity, 101 failure to show in radiograph, 118 lapping the teeth, 112 number of teeth involved, 105 of tooth with vital pulp, 19 shadows overlapping, 122, 124, 126 under silicious cement fillings, 11!^ very large, 146 Absence of x-ray machine, 98 Absorption, appearance of, due to angle, 105 of roots upper molars, 104 Age, 75 Amount current needed for test, 75 Angle of x-rays, 99, 100, 105, 118, 122, 144 Anterior palatine foramen, 101, 102, 132, 134 Antrum of Highmore, 102, 136, 138 Apparently sound teeth, 108, 109, 110 Application dental electrode, 54 B Bifurcation roots, lower molars, 150 Broken cords, 35, 60 (Fig. 29) C Cancellous spot, 104 Cavity, 78, 144, 150, 152 Cement fillings, 112 Changing plugs, 61 Chart, diagnostic, 43 Children, 90 Choice of point of application of dental electrode, 54 Choke coil, 31 Clinic, written, 87 Clinical value of test, 95, 96 Contact, moisture, 50, 51 Controls on Faradic machine, 45 155 156 INDEX Cords, 35 broken, 35, 60 (Fig. 29) Cortical bone shadows, 138 Cotton holder, 41 Crowned teeth, 57 Criticism of test answered, 91, 94 Current (electric) : amount needed to test, 75 gradation of, 29, 45, 46, 47, 50 immunity to, 78, 79 safety and danger, 24 source of. 23 tracing through Faradic machine, 24 tracing when used, 48 Cyst, 136 D Danger of current, 24 Dead pulps without periapical bone change, 99, 116 Defect, in Faradic machine, 28, 29 Dental electrode, 36, 37 wrapping, 52 Dental mouth mirror, 42 Dental switchboard, 30 Dentin, exposed, 78 secondary, 76, 114, 140, 142 Dento-alveolar abscess, (see abscess) Diagnosis, dijfferential (see differentiation) Diagnostic chart, 43 Diagnostic opening, 77 Differentiation : abscess and anterior palatine foramen, 101, 102, 132, 134 abscess and antrum, 102, 136, 138 abscess and incisive foramen, 101, 102 abscess and large cancellous spot, 104 abscess and large periapical space, 104 abscess and mental foramen, 101, 126, to 130 abscess and nasal fossae spots, 103, 140, 142 abscess and nostril spots, 103 abscess and partially formed root, 105, 144 abscess and pyorrhea, 106, 148, 150 abscess and radiolucent area in region of upper lateral in- cisors, 103, 140 between pulpal and gingival sensation, 81, 82 Disto-buccal roots, 142 INDEX 157 E Electric test (see test) Electrode, dental, 36, 37 hand, or indifferent, 38 wrapping, 52 Electrophobia, 86 Effect of fillings on current needed, 79, 80 Enamel, thickness of, 75 unsupported, 59 Erosion, 78 Exposed dentin, 78 F Factors modifying current needed, 75 Faradic machine, 23, 28 appearance, 25 controls, 45 defect of, and how to overcome, 28, 29 modified, 26, 28 parts of, 24 safety of, 24 three sockets, 29, 45, 46 tracing current through, 24 transportability, 26 Fillings, cement, 112 effect on current needed, 79, 80 large, 57 silieious cement, 112 Fistulous tract, 110 Foramen, anterior palatine, 101, 102, 132, 134 incisive (see anterior palatine) mental, 101, 126 to 130 Fossai, nasal, 103, 140, 142 G Gradation of current, 29, 45, 46, 47, 50 H High-frequency machine, 32 Immunitv to current, 78, 79 Incisive foramen, 101, 102, 132, 134 Indistinct root outlines, 144 Inferior dental canal, 103 158 INDEX Insulation of teeth, 58 Ionization machine, 30 Irritation point, 47 L Lamina dnra, 126 Large fillings in teeth, 57 Limitations of the test, 83, 85 M Machines for pnlp testing, 23 choke coil, 31 Faradic, 23, 29 flashlight, 33, 34 high-frequency, 32 ionization, 30 switchboard, 30, 31 testing out, 61 transformer, 31 x-ray, absence of, 98 Maxillary sinus, 102, 136, 138 Medicine dish, 42 Mental foramen, 101, 126-130 Mirror, dental mouth, 42 Missing test records, 122, 124 Modified Faradic machine, 26, 28 Moisture, 51, 52, 76 Moisture contact, 50, 51 Molars, upper, roots of, 104 N Narcotics, 76 Nasal fossae, 103, 140, 142 Nervous patients, 86, 89 Nostril spots, 103 Number of teeth involved in abscess, 105 Oblique ridges, 152 Opening, diagnostic, 77 Osteoclasia (also see abscess), 100 Outfit (for pulp testing), 35 Overlapping abscess shadows, 122, 124, 126 Pain, 56, 57 Parts of Faradic machine, 24 INDEX 159 Patients, children as, 90 nervous, 86, 89 Periapical space, large, 104 Pericementitis, 80, 120 Peridontoclasia (see pyorrhea) Plugs, 35 changing, 61 Polarity, 45 Pulp, dead without osteoclasia, 99, 116 recession, 140 stones, 78, 114 testers (also see machines), 23 Pyorrhea, 106, 148, 150 R Eadiolucent area in region of upper lateral incisors, 103, 140 Recession of pulps, 140 Record blanks, 42, 44 Response from abscessed tooth, 92, 93 Root, outlines, indistinct, 144 partially formed, 105, 144 resection, 148 Roots, bifurcation of, lower molars, 150 disto-buccal, 142 of upper molars, 104 Rubber dam insulation, 58 V S Safety and danger of current, 24 Secondary dentin, 76, 114, 140, 142 Sensation, 56, 57 Shadows overlapping, 122, 124, 126 Shock, 24, 61 Silicious cement, 112 Sinus, maxillary, 102, 136, 138 Sockets, Faradic machine, 29, 45, 46 Sound teeth (apparently), 108, 109, 110 Source of current, 23 • Suspicious areas, 114 Switchboard (dental), 30 Systemic disease, 96, 97 T Technic : fundamentals, 45, 49 handling children, 90 160 INDEX illustrated, 63-74 of application of electrode to teetli, 54, 55 of applying electrode to filling, 58, 59 of applying test for nervous patients, 86, 89 of controlling tongue, 52 of keeping teeth dry, 51, 52 of making moisture contact, 50 of wrapping dental electrode, 52 of steadying hand, 51 valuable point, 50 Teeth : crowned, 57 insulation of, 58 sound, apparently, 108, 109, 110 with large fillings, 57 Test (electric) : advantage of, 21 compared to other tests, 20 harmless, 86 limitations of, 83, 85 records, missing, 122, 124 reliability of, 21 safety of, 21 to check all x-ray findings, 98, 99 value of, 95, 96 Testing machines (also see machines), 23 Testing out machine, 61 Testing outfit, 35 Transportability of Faradic machine, 26 Tracing current used, 48 Tract, fistulous, 110 Transformer, 31 Trouble, 59, 60 Tweezers, (cotton), 42 Unsupported enamel, 59 Upper molar roots, 104 Value of test, 95, 96 U V w Wrapping dental electrode, 52 Written clinic, 87 X X-ray angles, 99, 100, 105, 118, 122, 144 X-ray machine, absence of, 98 COLUMBIA UNIVERSITY LIBRARIES This book is due on the date indicated below, or at the expiration of a definite period after the date of borrowing, as provided by the rules of the Library or by special arrange- ment with the Librarian in charge. DATE BORROWED DATE DUE DATE BORROWED DATE DUE lu.^- T — ■ ,_^i,.:^ i 1 C2e(ll4l)M100 1 RK265 Raper Electro- rridiographi K18 Copy 2 ° (diagnosis. flectro- (hsi.stxj 2002339986