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it, however, for the similarity of the zinc oxide that has been highly calcined and that prepared from the nitrate caused us to believe that many, if not all, the more modern cement powders, such as Caulk's, Ames', and possibly Smith's were made from the nitrated rather than the calcined product.
Our work on bismuth was the last that we did and consists of but a comparatively limited amount of work to that which appears may be done on this material. The salt of bismuth that we had assumed was used by the manufacturers was the tri-oxide (Bi203), which is a yellow powder. With cement liquids and phosphoric acid it appears not to set. At least it did not set in the time that we watched it. It mixes with cement liquid into a perfectly smooth, oily appearing
On heating it melts, turns reddish brown and becomes crystalling when cooled down. A series of experiments to determine what temperature would volatilize it showed that above 500°C there was considerable loss.
A series to determine what temperature was necessary to make it combine with zinc oxide and magnesia showed that between 600°C and 700°C it began to impart its yellow color to the zinc oxide and magnesium oxide, and at 800°C no further change in color could be made by the heating. From this we concluded that there was likely to be a variation in the quantity of bismuth tri-oxide in our synthesized cement powders unless we determined the extent of the volatilization at the temperatures found necessary to combine the bismuth tri-oxide, magnesium oxide and zinc oxide in such powders as Petroid, and made allowance for it under well controlled temperatures necessary to combine the three. This, however, we did not get time to do.
We did try one or two syntheses of Petroid light yellow powder using 84% of nitrated zinc oxide, 10% of magnesium oxide, and 6% bismuth tri-oxide. The three constituents were placed in a ball
mill containing one dozen 34 inch porcelain balls, and revolving at 68 revolutions a minute and mixed for six hours. They were then taken out and placed in an unglazed Royal Berlin crucible, that had a lining of a mixture of zinc oxide and zinc chloride and had been fired for 10 hours at 1400°C. The crucible containing the three constituents was then placed in the electric furnace which was running at 770°C and left for 30 minutes. At the end of this time the three constituents were fused into a clinker which had to be broken up into pieces to get it out of the crucible. These pieces were then placed in the ball mill containing one dozen 34 inch porcelain balls, one dozen balls 12 inch in diameter, and revolving at 68 revolutions a minute. This powder was then removed and placed upon a bolting cloth of 180 mesh to the inch and that which passed thru the cloth tested with the liquid which accompanied this powder.
While we are not certain that with more fully developed technic we could improve this product for dental purposes, we feel certain that it is along these lines that this powder is made because of its similarity to the original powder. The thing of interest at this time was not much the technic employed by the makers of this product as to determine something of the effect of the bismuth. In this case the result was similar to the one reached when we fired zinc oxide and bismuth tri-oxide without the magnesia, viz., it gave a product much smoother in working properties.
While these tests are but a few suggestions for future workers we feel safe in saying that the use of bismuth trioxide and probably other bismuth salts is the principal distinguishing feature between the more modern, smooth working, quick setting, hydraulic cements, and the older varieties containing zinc oxide only in the powder portion. Our reason for saying that probably other
bismuth salts are used in these powders is that when Petroid Light Yellow powder was heated to about 800°C it turned a deeper yellow, while the same treatment of Ames' Pearl White would remain white, both powders showing bismuth on analysis.
While much of this work needs to be checked over, and other parts carried to completion before definite conclusions are drawn we believe the main part of it will serve as a basis for future workers on the subject that will enable them to go over our work in much less time than we have consumed. It appears to us that enough has been done to show the necessity for more work on the subject for the sake of the literature which seems to be several years behind the more progressive manufacturers. The lack of papers on the subject of cements before our societies, in fact, the lack of
practically any discussion of the subject appears to be further evidence of the feeling of the profession towards the literature, and an acknowledgment of the inability of the teachers and practitioners alike to discuss the subject.
For the benefit of the literature, students entering upon the practice of dentistry, and those already engaged in the practice of dentistry we urge that work along this line be carried on until the composition and properties of the different classes of cements becomes common knowledge.
"Erratta : In an article entitled 'Dental Caries', by W. R. Bunting and U. G. Rickert which was published in the August issue of The Journal for the present year the following error appeared. On pages 252 and 253 the tabulations which were given of various amounts of Cal in 25 ccm, of saliva should read grams instead of milligrams.
By Donald Mackay Gallie, D. D. S., Chicago, Ill.
To the Members of the House of Delegates of
the National Dental Association.
MONG the many recommendations
made by my distinguished prede
cessor, Dr. Homer C. Brown, was one to the effect that the President of the National Dental Association should prepare, deliver and have distributed, a president's address. Like many of his recommendations this one was concurred in by the committee appointed to report on his message. The Constitution, however, comes to your rescue by stipulating that the address shall not exceed fortyfive minutes in length. A strict interpretation of these recommendations hardly applies to this year's officer, for, technically speaking, we are holding not meeting of the National Dental Association, but a meeting of the House of Delegates, for the purpose of considering such business as an association of our size and many interests require. However, your President feels that a brief resume, of the many departments and interests should be presented at this time.
When we were invited three years ago at Washington to join with our Pacific Coast friends for the purpose of holding a Dental Congress, we were assured by the emissaries sent by the Panama-Pacific authorities that it was their idea to have this congress mark an epoch in dental affairs; that their hopes are to be realized, I am sure is apparent to all. In behalf of the National Dental Association I desire to thank our colleagues in this great western section for the opportunity of joining with them in this ten day session to discuss and consider the many
questions so vital to us as a profession. I also desire to express in behalf of the dental profession of America our thanks to the Panama-Pacific officials for the opportunity of taking part in this great National, yes, International celebration of the completion of one of the greatest achievements of all times; the joining of the mighty waters of the Atlantic and Pacific; the surmounting of obstacles that for years have baffled the greatest engineers. The engineering success of this great waterway is not the only thing the world should consider. There is still
greater achievement in connection with this wonderful undertaking and that is the triumph of sanitary science and medical skill, making it possible for human beings to live in the Canal Zone. The complete transforming of this zone from one of pestilence and disease to one of health, comfort, and in many ways beauty, is the greatest triumph of all, and the man who deserves all the credit is Surgeon General W. C. Gorgas. In planning and carrying into effect this wonderful exposition, it was not the idea of those responsible for its conception, to celebrate this national achievement simply by building wonderful structures to house exhibits of all the arts and crafts--not merely to show the products of the work shop, the soil, forest, mines and seas, but also to show the advancement of the world in affairs not industrial or commercial, and to this end a department of Congresses is one of the great features of this wonderful exposition. No fewer than eight hundred and fifty congresses, conventions and conferences will be held between February and December, every phase of human endeavor will be represented.
In reading over the list of different gatherings, I find none are giving more time to their particular field than dentistry and this is not surprising, for have we not made such strides that it will take some time for many of us to catch up? Not only is the attending of dental meetings a necessity, but systematic and constant study is imperative if we hope to be worthy of our great responsibilities.
In the convening of the several dental bodies connected with this Congress how grateful we should all be that the opening is under such favorable conditions. We are here celebrating an event that tends to bring the world closer together, to make the whole world akin. Compare this with the opening of the last dental congress. The commencement of a conflict between great nations, the like of which never was thought of. These are sad days for our colleagues in Europe. The sympathy of American dentists goes out to our brothers across the Sea, and the prayer of all, I am sure, is that this terrible war will terminate ere long.
bers have answered the last summons. Their works will live. The imprint they left on the profession will ever be visible, their high ideals a heritage to us all. In spite of the terrible European conflict which has cast a pall over the whole world, and in spite of the unsettled business conditions of our own land, the association and the profession has enjoyed a year of unparalleled success. Last year at Rochester was the first meeting after re-organization, for years we worked for a greater National, and when at last our labors were rewarded by the uniting of our state and local societies under the guidance of this, the parent body, when at last there was no division of our interests; no scattering of our fire. Just a grand national organization of over thirteen thousand, with one aim—the improvement and advancement of dentis. try. There were, however, some who were a little inclined to be pessimistic, and warned us to look for some reaction, that the enthusiasm and activity of reorganization would be followed by a falling off in membership. I am pleased to state that such has not been our experience. Hardly a state has shown a falling off during the past year, while a great majority have made splendid gains; be. sides we have benefitted by some additional states perfecting re-organization and now affiliated with the National. The past year has shown a growth of about three thousand members. This is indeed encouraging.
THE ROLL CALL.
During the past year the profession of America has suffered the loss of a greater number of prominent members, than in any one year within my recollection. Four ex-presidents of this National Association, which is the successor of the American and Southern Associations, have passed to the Great Beyond, namely, James Truman, Philadelphia; Charles R. Butler of Cleveland, M. W. Foster of Baltimore and F. J. S. Gorgas, Baltimore. The National Dental Association has suffered the loss of a number of its officers. T. E. Turner, St. Louis, Third Vice-President; H. B. McFadden of Philadelphia, Treasurer, George Edwin Hunt, Indianapolis, of the Research Commission, and W. E. Walker, of New Orleans, Secretary of Section III. Many other notable mem
THE NATIONAL DENTAL JOURNAL.
Next to reorganization the question of a National Journal has been uppermost in the minds of our members. It has been the hope of many for years that we should publish a journal that would be a credit to an organization of national scope. At last our hopes have been realized, and while it is not a monthly publication, I am sure you will all agree that in the quarterly form it is indeed something we can be proud of. We are all anxious to have a monthly journal, with
a regular elected editor and staff, but to do this means capital. To secure the necessary funds we will have to raise our dues. To raise the dues at this time I believe would be unwise. In the near future when we have perfected reorganization plans it will be an easy matter to change from a quarterly to a monthly issue. There may be some of our members who cannot understand why any one should object to the small increase in dues to make possible a monthly journal. Yet the Secretary has evidence that in some sections of the country where organization is more difficult, it is all they can do to meet the present requirements. With reorganization almost completed, a rapidly growing membership, the journal an established fact, it should now be the duty of the association to look to the future and plan for the business management of our interests. To this end the Ad Interim Committee of the Board of Trustees took the first step at Ann Arbor. The Treasurer was instructed to take 20% of all advertising funds and place it into the Journal fund. The advertising space in the Journal is rapidly growing in value, and the amount set aside will soon accumulate into a splendid amount which can be well invested until we are in shape to have our own publishing plant. The American Medical Association started with prospects no brighter than the National Dental Association; today they have one of the finest publishing and administration buildings in this country. The future of the National Dental Association is no longer a dream
vision; it is a real, live, healthy fact.
has been carrying on research work they have furnished laboratory technicians and laboratory equipment and supplies to assist in special research in several states. In the University of Michigan Dr. Marcus L. Ward is working on the problem of Dental Cements, and Dr. Russell W. Bunting on Salivary analysis and Dental Caries. In the University of Minnesota Dr. Thomas B. Hartzell and his associates are contributing reliable data on the Relations of Mouth Infections to Systemic Infections. In the University of Illinois Dr. Frederick B. Noyes is working on the question of the Dental Pulp and Peridental Membrane. In Columbia University, New York, Dr. William J. Gies and assistants are studying the Relation of the Glands of Secretion to Dental Problems. In Cleveland, under the direction of Dr. Weston A. Price, much work has been done in Metallurgical Researches and Studies the Identification and Differentiation of Serious Mouth Infections. These are only a few of the many vital problems the Commission will endeavor to solve. The financial contributions towards this great work has been very gratifying up to date. Between fifty and sixty thousand dollars has been subscribed, and this almost exclusively by members of the profession. This liberal support will have a great effect in influencing aid from laymen interested in the advancement of science.
Acting under instructions from the National Dental Association the Commission has broadened its field of activities, by incorporating in the State of Ohio the Research Institute of the National Dental Association. The Commission has secured the cooperation of many of the most prominent men in the medical pro. fession, and laymen of international standing. It will be the plan of the Re. search Institute to establish and support researches in various parts of the country, and to prepare and train young men for research work.
THE SCIENTIFIC FOUNDATION AND
RESEARCH COMMISSION. Organized less than three years ago, but working as a Commission only two years; this very important department of our association is doing a great work and the results of their labors will soon be reflected thruout the profession. During the two years the Commission