tions with their consequent evils, grave as they may be, should not be charged against the correct radiographic outfit where the technique has been standardized.

Only one thing need be guarded against when this has been properly done, and this is the change in the tube. If the operator sees that this is kept to a certain pitch, the machine will always be efficient. Very justly, however, there has been great criticism of the incorrect interpretations that have been sent to dentists and some of them from dental radiographers. Inasmuch as this criti

cism tends to interfere with the use of the great diagnostic aid in dentistry, it is unfortunate.

The real cure for this evil would be in doing away with the general radiographer and having every dentist do his own radiography.

This practise is becoming more and more general as the dentists comprehend that the best Roentgenogram diagnosis can only be made by the dentist who is familiar with the observed tissues in a given patient. The smallest detail in this history of what has transpired to those tissues can frequently be the deciding point in a case of doubtful diagnosis. In this respect the value of a correctly kept charted record of dental service can not be too highly estimated. Without this knowledge of that minute history the dental radiographer can easily err in his interpretation of a referred patient; how much easier is it for the medically educated radiographer to err? In reading many of these incorrect interpretations I have been imprest by the reckless and fearlessly positive way in which these pictures are misinterpreted.

The correction of this matter is not difficult. The radiographer who is not the attending dentist has no legitimate claim to act as the interpreter of the picture. He may by his advice in explaining what the dentist may fail to

see, become a most valuable consultant. The dentist, even if he has no outfit, should make the interpretation of Roentgenograms a study so that he knows the nature of tissue he is looking at. He then will apply his knowledge of conditions present and past to the case, and the opportunity for error will be greatly diminished.

There is no fault to be found with the essayist on this important matter, because as far as he is concerned, he covers the ground when he says, "Pathologic conditions may only be assumed, never asserted." He says this in the capacity of the referred radiographer or for that matter, of the dentist where he sees the patient for the first time.

The question raised by the essayist of the difficulty of diagnosing a blind abscess with but little destruction of hard tissue is of great importance. Just as the expert microscopist becomes more adept at tissue reading with every increasing study of specimens, does the dentist increase his ability to correctly interpretate by continued study of negatives. In cases of difficult diagnosis of this nature, it has seemed advisable at times to keep the negative under constant observation for a couple of days. After picking up such a negative and observing it for the twentieth or fortieth time sutle factors in the tissue will often manifest themselves suddenly and thus clear up the diagnosis. In this respect a powerful magnifying glass is often of value. The case cited to show that a film would overlook an abscess in a bicuspid where the original acute trouble is in the molar could never apply to a good diagnostician.

The assayist has very kindly seen fit to draw attention to some of my specimens of bone reconstruction, but questions the proof of the tissue being free from pathogenic germs. His question might be answered by the question, why does not all post operative Roentgenograms show newly constructed bone? If

the operation was such as sufficed to remove every particle of pathologic tissue in the peri-apical space, and the periapical end of the root opening securely covered by a non-irritating aseptic filling material, where would a new pathogenic germ come from and where could it locate? These are the two essential factors necessary and where correctly applied reinfection is impossible. Whenever a root filling does not pass thru the end of the root so as to cover the outside of the foramin it renders that point a seductive point of habitation for any ambitious micro-organism. On the other hand nothing is more easily destructive of tissue than forcing thru the foramin of root fillings of some irritating substance; oxychloride of zinc cement and filling materials containing formalin in the smallest quantity are specially productive of tissue destruction.

An important point for interpretation is pulp nodules. The properly prepared film shows these with great clearness, but like many other points must be left for some other occasion.

R. Ottolengui, D. D. S., New York City, N. Y.

There is so much in this paper with which I heartily agree that I trust the essayist will be satisfied with this statement and will forgive me if I discuss only those parts with which I disagree. I can agree also with almost all Dr. Rhein has said. There is something, however, in both the essay and the discussion with which I am in such violent discord that I must ask your patience to get it out of my system before I come directly to the subject of the reading of radiographs. I am going to try to drive a nail in the coffin of that word "Roentgenogram." I would like to see that buried forever. I know very well that the Roentgen Society has recently adopted that terminology, but I need go back only to the essay of this afternoon to show the foolishness of it, because in

one place the author says "Roentgenogram" and in another "radiograph," and in science we know that the fewer terms we have for the same idea, the better. These gentlemen have said "Roentgenogram" because the Roentgen Society tells them to say so. Why should the Roentgen Society use this term? Because they wish to connect this man's name permanently with this science, because they wish to erect a monument to him in the language. That is not the purpose of a language. We have places where we can put up stone buildings for monuments. Go back to the beginning of electricity. Franklin was the first man who called our attention to the fact that we could make use of it, but we do not speak of Franklinology, and still we have not forgotten Franklin. Fulton first showed us how to run a boat with steam, but we do not call steam navigation Fultonology, nor do we forget Fulton. We name streets after him. I am willing they should build a whole town in Germany and call it Roentgenville, but I am opposed to building a monument to this man in our language, and especially to use a word that is so difficult to pronounce by anybody except those of German extraction (Laughter). No body of scientists has any right to interfere with the rights of any other body of scientists, and before the X-ray was discovered, before the Roentgen Society was formed, before anybody in that society was born, before Roentgen was born, we had the science of etymology and we had philology. The etymologist is the one to trace to formal rules the proper construction of words introduced into one language from another. The philologist is a man who endeavors to make language euphonious and correct by having a set of terms constructed in some order, so that the terminology will have some correlation with its structural form. Let us see what these men have done. We have the word "telegraph," from "telon," far off, and "graph," to

write. When the wireless telegraph came in, we were at a loss for a word, and for a long time they called those messages wireless messages. Later, and fortunately, the term "radiogram" not having been preempted, it has been taken and is now being used for the message sent by these electric waves, so that the ra diogram is something written by the ray, using "gram" in the participial form. "Photograph" from "photos," light, and "graphs," to write, writing with light. And "radiograph" is a beautiful collateral word, writing with the ray, and especially so as we use this photographic process to do it. "Phonograph," writing with sound; "Stenograph," written in short words, and a number of other words which are all collateral in construction, and whose meanings can be definitely determined by that construction. In addition to that, to have the adjectives and nouns that go with them all easily differentiated. We have photograph, photography and photographer; radiograph, radiography and radiographer. In addition to that we have the word "radiology," and here "radiology," as distinguished from "radiography," is the science which deals with the entire use of the ray, including the therapy as well as the radiography. In other words, radiograph would be a branch of radiology. I hope I have the grave deep enough so that the sexton will be able to bury that word and plant flowers over it. We must keep it out of our dental literature (Applause).

I want to agree with Dr. Rhein, and disagree with the essayist, in the matter of the use of plates. In order to do that I want you to consider another statement he made, and which is made by a number of radiographers, and that is that these radiographs are records of varying densities. That is in a certain sense true, but I do not like the word "density." What it really is, is a record of varying resistance to the ray, and resistance to the ray is not always

density. The trouble about the word "density" is that to one mind it carries the idea of atomic weight, and to another it carries the idea of hardness. In the first uses of the X-ray, a common experiment was to put a person's hand on the table, put a book over it, and cast the ray thru it. You could put a dictionary over that hand that would weigh ten pounds, and that would not have any great density in the sense of hardness, and get a perfect picture of the hand. But put a thin sheet of lead over it, which was only one pound in weight, and which had a greater density in the sense of hardness, and you wouldn't get any picture at all. So in the last analysis, your radiograph is a record of varying resistance to the ray. Apply that to this specific thought. What do we want in these dental radiographs around tooth roots? We are not anxious to get the profile of those roots. We know or can guess how many roots the tooth has. Sometimes we may want to know the length. But because of the fact you have taken the teeth in two jaws, you never get the identical length of the tooth; you always have some distortion. You do not always have distortion in the film; that will depend on the anatomy of the parts and skill of the operator, and we will have radiographs sufficiently skilled to give the exact measurement of teeth from radiographs. But what we want it for is to study the disease in that tissue, and that depends on the nature of the bond surrounding these parts, the presence or absence of the bone mesh and the condition of that cancellous structure. If you take a picture of a skull from which all the soft tissue has been removed, you get a well defined reticulation of the bone. That proves that in life the presence of this tissue, altho of very little density and of very little atomic weight, does interfere with the transmission of the ray, and does blur your picture; hence

the less soft tissue there is between the parts you wish to read and the plate, the better. When you place a film at the lingual side of the tooth, and especially is this true in the lower arch, you have nothing but a very thin layer of gum interposed between your plate and the bone of which you wish a record. When you use a plate, you have all of that and all of the cheek tissue besides, and that is the reason why there never was as good detail, in a plate picture made by the best man with the best processes, as compared with the film, made by the best man under the best conditions (Applause).

Elmer S. Best, D. D. S., Minneapolis, Minn.

a

I first want to commend the essayist upon the work he has done in standardizing this particular field of work. I have learned much from the essayist in establishing this work upon really scientific basis in making an examination such as we are soon going to be called upon to make, of the entire jaws, upper and lower, for the physicians and surgeons, in endeavoring to locate the cause of certain systemic troubles which they believe have their origin in the jaws. The great difficulty I have experienced in making a complete examination without the use of plates, of all the conditions of all the lower and upper jaws, is in the great number of small films which it seems necessary for us to use, and also the over lapping of one film with another, and when you do not have the patient there to check up your examination, the possibility of confusing the teeth on the right side with those on the left side. I therefore say again, I want to compliment the essayist. If he has not done anything else, he has given us something of great importance, when, with four exposures, he can give us all the teeth and the adjacent parts on the left side forward to the cuspid and on the right side forward to the cuspid, and then with the film of the

upper and lower anterior teeth, he has disclosed to us the entire field we wish to investigate. You can then if you wish, check up those findings by taking an exposure of the part which you suspect.

I also agree with him that it is almost impossible to locate definitely with a radiograph those cases where we have putrescent pulp tissue with no bony destruction.

There are certain objections we have to the use of plates, aside from some of the objections which have been mention ed, and that is that possibly we do not get the same detail in the plate which you get in a film; yet I must say that I have seen some plates taken by the essayist which contain just as fine and minute details as I have ever seen. Another objection we have to the plates is that it is rather difficult and uncertain in handling them. If you should accidentally drop a plate, it is likely to break, and your record of that case is gone, if you cannot get another. I believe the Eastman Kodak Co. will supply us, in almost the immediate future, with a film of almost any size we may desire, whereby we can get practically the same image we can with a plate. That will help tremendously.

Dr. Rhein brought up an important question when he mentioned the importance of having a man thoroly versed in the knowledge of anatomy of the teeth and jaws doing this work and making the interpretation. This is distinctly a dentist's field.

In examining a great many cases where there is defective root canal filling, we have found conditions which are enough to make any man in the practise of dentistry thoroly ashamed of what he has been accomplishing. These people, on account of not having a manifestation of their trouble in the mouth, are not going to return to their dentist to have their trouble eliminated; they are going to their family physician, and what is

he going to do? Being unable to locate the cause of this trouble, which has a systematic manifestation, he is doing as a great many of them are doing now, having the jaws radiographed, and what are they going to find, when I tell you that at least 90 per cent of all the root canal work we have been doing in the past is defective and that a large per cent of your work is causing trouble? And yet the men who did the work do not believe it is causing trouble. What is our position going to be when these patients come back to us with their physicians showing the entire jaws radiographed, and where we have in one, two, three or four cases performed an operation which has resulted in damage to that patient's health? We must therefore consider the operation of root canal filling as one of major importance, and the only way in which we can intelligently do it, with any degree of credit to ourselves is by the continued use of the radiograph.

DR. F. W. LOWE, of Buffalo, N. Y.

I feel inclined to be convinced that all the discussers are right. You are not allowed to depend upon the radiographer, or upon yourself; you are not allowed to depend upon the plate, and not upon the film. I don't see what you can do but pull out all the teeth. I want to tell a little story to show we must have both the film and the plate. I have seen a fistula well down upon the neck, and all the swelling that showed was well un der the jaw, well under the rim. An accident to the jaw two or more years before, the fistula and swelling made their appearance had occurred, and things had been cleaned up, and the man was supposed to have spit out all the teeth knocked loose. When these later manifestations occurred and the physician and surgeon consulted, they opined it couldn't have been anything attributable to the teeth, because the teeth appeared to be normal. However, a film was ta

ken, and nothing showed except a little apparent density just at the edge of the lower jaw. Then the radiographer put the patient on his head and took another picture from below up, and we found that as the result of that accident, a tooth had been broken off above the neck, leaving the entire root in, and that it had turned a somersault so that the big end of the root was downward, and it was just at that rim of the jaw. The small film showed nothing; the first large plate taken from the outside showed nothing, except that very slight density, but the picture taken from underneath the jawshowed that tooth in perfect contour. We cannot take too many pictures. When a fellow is 63 years old, as I am, he can not begin to do his own radiography; he won't live long enough to become expert. There is only one solution; you must rent a house, find an expert radiographer, a general one, a good one, and then plant him right under your office. I am going to take Dr. Eisen home with me, and am going to have a radiographer (Laughter).

DR. W. A. GIFFEN, Detroit, Mich.

We get better detail and less distortion in a radiograph made on a dental film than from a plate, for this reason, that we can get closer to the focal point.

The Eastman Kodak Co. are now making films of various sizes. I have been using 8x10 films for fractures and other cases where there was more or less swelling, and they work out nicely. By placing the patient's head on a soft pillow, you get adaptation as close to the bone as possible by compressing the tissues between the bone and the film. This method certainly minimizes the distortion.

Regarding the statement that the general radiographer is unable to correctly diagnose many of the lesions we have to contend with, I believe the reasons are because as a rule he is not so familiar with the practise of obtaining the