The future of dental radiobiology

THE FUTURE OF DENTAL RADIOBIOLOGY

OW will the dentist of the future use radioactive materials I Answers to this question are presented in Table 1. which is divided into two vertical parts. The clinical or direct uses are those which are applied directly to the patient (columns 2 and 3). The experimental or indirect uses are those which will ultimately benefit the patient through the improvement of dental materials (column 4), the achievement of new understandings of biological processes (column 5) and oral diseases and their treatment (column 6). Clinical applications at present iIre primarily to be found in the field of medicine. For example. in column 2 radioiodine in small tracer doses is noted as a direct means of measuring the activity of the thyroid gland. Another major use (colum11 3) is to destroy unwanted tissue by the radiation released from large (therapeutic) doses of radioisotopes. In each of these types of applications (first row) there are several natural and several artificial radioisotopes (second row) whic.11 are in clinical use. There are also certain compounds which have been labeled wit,h radioisotopes (third row j and which arc useful for special purposes such as the treatment of tumors in particular organs. When there are rapidly spreading tumors in the peritoneal ca,vity, for example, radioactive gold in the colloidal form can be injected into the peritoneal cavit.y. In this form gold tends to coat the surfaces of the cavity and, although it must stay in the peritoneum, it will tleliver its radioactivity rather quickly. since it has a half life of 2.7 days. and revert to an innocuous stat,e. In fact, radioactive gold has many adrantages oyer the long-lived natural radioisotope, radium, and it,s short-lived daughter element, radon. which is a gas. The most promising dental applications are undoubtedly in the field of dental materials (column 4). The heavy metals, which are so important to dentistry, are the easiest of all the elements to ma.ke radioactive. In most instances metals can be bombarded directly and made radioactive in a form ready for use. This is quite different front the light, elements which are often very difficult to prepare, difficult, to concentrate, and require chemical synthesis to put them into a compound suitable for LIW. Twenty-three elements found in denture bases. filling materials. and cements are listed. Even components of inrestnients and fluxes ill't' readily obtainable in the radioactive form. What is so magical about radioactive metals and how would they be used? If we want to tletermine whether the mercury in an amalgam filling stays put after we place it, t,his is relatively simple to do in an experimental animal, or for some purposes even in an extracted tooth, by using radioactive In the radioactive form mercury can be traced and its penetration mercury.

H

The

From Read Desert

the Department of Radiology, University of Illinois College of Dentistry. before the Ninth Annual Seminar for the Study and Practice of Dental Inn, Palm Springs, Calif.. Oct. 28. 1952. 420

Medicine,

REQUIREMENTS

HAI)IOACTIYE COMPOUNDS

NATURAI, AND ARTIFICIAL RADIOISOTOPES

APF’I’I,ICATIONS

(1)

USES

‘(3) I I

I,

I.

DENTAL

RADIOACTIVE

I

IN

(5)‘

(INDIBECTI~

BIOLOGICAL

EXPERIMENTAL

DENTISTRY

/

ORAL:%AYES

p32,

A~‘l6,

Zn65

Fls, C14, Ss5, Cara, Ilal,

Caries Osseous and gingival antes Infections \Vound healing Tumors

USES

phaoa,

disturb-

Inorganic compounds Organic compounds : CiQuccinic acid ‘Medicaments : AgimNOa Cl4-urea Carbohydrates : CrQucrose 04.glucose Antiseptics : Hga~~trC’]~ Antibiotics : W-penicillin IreI-penicillin Carcinogens : Cle-methyl cl~olanthrene Bacteria : B. coli Antigens

‘I

Procedures : Selection of radioisotope Synthesis of radioactive compounds Detection and measurement (counters) Localization (survev and detail radioautograuhs) Identification ‘of metabolites (radiochromatography)

MATERIALS

(4)

TRACERS

PROCESSES I l’umors and t,heir I Castings : urecious and bas e( :rowt~h rTutrition metastatic lemet& sions Plastic denture bases: VU1[_ 3inesthesia Metabolic disturbcanite, acrylic, and styren e antes types Filling materials: amaigams ‘1 zinc oxyphosphate and silj icate cements, autoset-resins Plaster, investments, fluxes Hg203, 205, Aulss, Agrrc, Znct ia, Po latiium (Ra) CUM, Ni59, Cdll5, 109, Cr5: :14, ClR6, pan, C&45, NRZ~, 2adon (Rn) IrlQ2, rrl94, pd103, Tal82, Be: K42, 1131, SW, H3, :060 ?32 Belo, Mn52, Mns4, V49, Fess Hfisi, Garn, Brs4, Fls, :I31 58, Sb125, \V185, Cads, PXZ SrQo, Zn65 ~UlOX ph203, &IL?, Sa5, $98 -___ :06fl-metal Metals iitamins : C14-thiamin UadWO~, NaIlsl Oxides Cl*-nicotinamide luias-colloid Inorganic compounds : Cl*-ascorbic acid HaP3204, CaWOa Iormones: estrogens NaFls, H320, ZncaO ‘roteins : Amino acids Organic compounds : >arbohydrates Ci4-styrene “ats C14-Inetllacrylate monomer kiesthetics and analgesics : Pentobarbital, Pentothal, procaine

RADIAT!ON TIIERAPY

DIRE('T)

Personnel and facilities : Training Specialized equipment Protection from hazards Disposal of wastes

Xrculatorv and mrtaholic disturbances

DIAGNOSIS

(2)

CT,INICAI

TABLE

2

z

2 E

toward the pull) or the exterior determined in relation to the structures through which it passes. I:y determinin g whether the mercury moms about and where it goes we can proceed to the clerelopment of methods of controlling it. For the most, part we are in the dark about the processes which contribute to the maintenance or failure of restorations in the mouth. Countless biological ljrocesses such as growth, nutrition, and anesthesia (column 5) and oral diseases (columu 6) are open for in\-estigation with radioisotope-labeled compounds. The radiochemist and radiobiologist hare produced by the score radioactive vitanlins, hormones, proteins. carbohydrates. fats, anesthetics. and antibiotics. Sute how many of the compounds listed in the table utilize (‘I* as the radioactive label. This is an example of an isotope which is difficult of preparation and separation, and then it must be incorporated by chrlnical synthesis into aI1 appropriate molecule. The obstacales are very mnch greater than when preparing a radioactive metal. The use of radioactive materials requires (fourth row) specially trained personnel, specialized equipment and handling. E’ortunately the training is easily acquired and methods for dental radiobiology have been developed. Much fundamental information is analyzed for dental use in the Atomic Energy Issues of The New IFork Journcrl of Dentistry.1 The synthesis of a radioactive compound for a particular investigat,ion may invol re considerable expense. The investigator is fortunate if the cornpound is arailahle in a suitable form. The principal sources of isotopelabeled compounds are: The Isotopes Division of the IJnited States Atornir Energy Commission, university laboratories and commercial firms.4 A file of available compounds is maintained at Oak Ridge, Tenn., by the Isotopes Division of the TSAH’ anti current information is published by the Division in a periodical, Isotopics.” With such magnificent prospects for the future, dentists may feel that they are doing their utmost to aid the atlv;lncenlent, of dental science by attending the annual meetings of a state society, the national society, and a seminar. The tluml)cr Or tlelltkts who attend thE!C! nlajm’ nlet~hgs ;I year iS indeetl small, bat (‘\-en that is not enough attelltiolt to dentistry’s problems to .\s it is now the ljrogress of dental insure atlequate 1)roprcss in the future. science depends more 011 the progress of medicine and biology t,han it does upon the efforts of clentists. What can dentists in practice do to aid the progress of dental science? One of the most significant steps has been the establishment of the Seminars of Dental ?uledicine which have grown front their beginnings in this very groul) until now seminars are held in every section of the country. A more advanced step is the announcement of a monthl!- service 1)~ this Seminal which will provide the members with a continuous SOLI~CC of new information. There is more in\-olred in this than another subscription to a dental rrsearcll journal. This sthrvirc gives a tlertfctl .sr:ie:,lcc .scr.l*icr to the dental pr:r(dThis is a most effective way to show the dentist. his dependence titioner. upon dental science and its need for his interest and encouragement. Many dentists do not see the necessity for dental research. They do not understand why rrscarch stands first in the program of the American I)(‘llta 1

PITT17RE

OF DESTAL

RADIORIOLOGT

423

Associat,ion. They say, “Never mind the research, I don’t need that. Ii you have a new amalgam, don’t bother me with its hardness, shrinkage, etc., etc. Just give it to me. I’ll try it a few times and will soon tell you if it works! If you have a new local anesthetic solution, just give it to me and I’ll soon let you know if it works but don’t bother me with its pH, composition, toxicity, keeping qualities, etc. ” A moment’s reflection enables the discerning dentist to realize that if it were not for the research worker and the dental scientist, the new amalgam alloy or the new local anesthetic would not have been created in the first place. The development of a new product involves considerable research, much of it of a fundamental type far removed from the dental office. The discerning dentist knows, too, what great benefits come from an intimate knowledge of the problems of dental practice on the part of the dental scien.tist. Much is not obvious to surface inspection. Just as bacteria which may contaminate a local anesthetic solution must be sought with the aid of the microscope and cultures before a batch can be declared safe for distribution, much of the success of a new product, such as a filling material, can be predicted on the basis of the dental scientist’s physical and chemical tests. Yet, a new discovery cannot be accepted on the basis of laboratory evidence alone. Research is not for dental scientists alone. The dentist in practice and the ckntisi iI1 science ~must team up in order to hazqe dental science that has men&g. Where is new dental information to come from? Dental research is not something on tap like a book or encyclopedia that you can pull down off the shelf and in it find all the answers to your questions. Dental research is a living thing; it must be nurtured and constantly renewed; it is living people. Just as the practicing dentist wants to feel that his work warrants praise, the research worker continually needs attention and encouragement. In order to have dental scientists, dentists must see to it that there is sufficient monetary inducement to attract some of our finest young dent,ists into research. Dentistry must also see that there is a future for the research worker, something for him to look forward to. The hard-headed, calculating businessman reads the “ Industrial Research Newsletter” of the Armour Research Foundation, Illinois Institute of Technology.* The four-page issue of November, 1951, starts out: Laboratory lights burn late as researchers across the nation face problems . . in ina few of the headings as one reads dustry, in government, and in universities”; down the page are: “What . . . industrial executives want from research workers . . .“; “Graduate education essential to research . . .“; “Microscope for studying and photographing radioactive materials . . . “; “Faster drill designed for plastic materials . . . “; “New chrome carbide . . . “; “. . . research does not progress on a dollar basis . . . ” ; ‘ ‘ . . . negative research findings often . . . open up new fields . . . “; (‘New directory of . . . Scientific Apparatus Makers . . . )f.> “New $2,000,000 research building of Ames laboratory, . . . Iowa State College . . . Institute for Atomic Research . . . “; ‘(New go-acre research center in Tulsa, Okla. . . . ” ; ‘(Three Engineering Staff buildings, opened at . . .813

acre technical center . ” ; ” C&e !iistorics of services by independent IZllIOlXtories . . . ” The first Industrial Research Scwslctter that I saw was briny read by the passenger next to me on a plane trip. He was the sales executive of a rug Inanufaeturer. 1Iis conimcnt : ’ LReswrch is one of the nlost essential activities in our industry. 1 am a sales~nan not a resea~hn~an, hut I find it impossihle to do business unless 1 keep LII) to date on technical atlvnnws.~’ All too frequently the apl~roach of the delltill I)ractitioncJI* to the tlental scientist is something like this: “Hew is a gootl ~)t*ohlrnl : you’re the research man ; you investigate it. ” The attitnde often implied by the l)rwctitioner is that there is such a thing as a “research man.” ;I y?rson who stallcls apart from dentistry and is hardly to 1~ trustetl with a pat icnt. 17catayearly in one’s dental experience one learns that an wotlontist is not a specialist of such narrow vision that he knows only about the movemcwts involvetl itr the (~straction of teeth. One learns that an esodontist is mow than an estractionist ; of necessity he is also an expert dentist,, diagnostician, pathologist, anatomist, etc. In like manner there will he a dental science if the dental scientist is an espert dentist, diagnostician. pathologist, anntomist, etc. Many dentists do not see anythin g in dentistry heyontl the successful conduct of a dental practice. Others desire to do some’thing lo advance their profession. They lend a hand in the activities OEtheir tlistriet dental society. They attend meetings and refresher courses in odes* to learn new twhniqnes Some decide to undertake gradl~atc study. In and biological principles. very rare instances a dentist will decitle to make a thorough inyrstigation of of these hare a free-lance npproa~h to resenrc~h, some a dental problem. Solnc contbine teaching with research. To some it may seem that research and the preparat,ion for it follow >I road that leatls away from clcntistry. On the contrary, just as R problem starts at the dental chair and is then taken to the research laboratory, the results of investigation must .clo 7~~1; to the clinicim for wrification. The road to research one that leads to dentistry and dental service. In fact is an ever-returning and thtd sertic~. it is the future of dentistry References Atomic Energy Issues, New York J. Dent. 20: 280-330, 1950.; 21: 281-323, 1931. Industrial Research Newsletter, William A. Spencer, Editor, Armour Research Foundation, Illinois Institute of Technology, Technology Center, Chicago 16, Ill. Isotopics; Isotopes Division, United States Atomic Energy Commission, Oak Ridge, Tenn. (Subscriptions, $1.00 per volume from Superintendent of Documents, Government Printing Office, Washington, 25, D. (‘.) Sources of radioactive compounds: Isotopes Division, United States Atomic Bnergv C’ommission, Oak Ridge, Tenn. Isotopes Branch, National Research Council of Canada, Chalk River, Ontario. Canada. Abbott Laboratories, Department of Radioactive Pharmaceuticals, Dr. D. L. Tabern, Head, North Chicago, Ill:, and Oak Ridge, Tenn. Bjorksten Research Laboratories, 13791 South Arenue 0, Chicago, Ill. National Bureau of Standards! Washington, D. C. Nuclear Instrument and Chenncal Corp.. 223 West Erie St., Chicago 10. Ill. Radioactive Products, Inc., Detroit, Mich. Schwarz Laboratories, 202 East 44th St., New York 17, N. 17’. Southern Research Institute, Birmingham, Ala. Texas Research Foundation, Renner, Texas. Tracerlab, Inc., 130 High St., Boston 10, Mass. Vnited States Testing Co., Inc., Hoboken, N. J.