SPECIAL REPORT

Report of the 3 3 r d a n n u a l m e e t i n g of t h e A m e r i c a n A s s o c i a t i o n of E n d o d o n t i s t s H o l l y w o o d , Fla April 2 8 - M a y 2, 1976 H. D. Prensky, DDS

Displaying the Stars and Stripes unfurled, the cover of the program of the 33rd annual meeting of the A A E proudly announced the special nature of this year's reunion--a dedication to the 200th anniversary of the United States. To enrich the celebration, a large number of Latin American dentists attended, drawn to Hollywood, Fla, because of the Pan-American flavor instilled into the meeting and the fact that it was being held in bilingual southern Florida. In A A E President Robert Uchin's welcoming message, he said that the meeting was "an unusual opportunity to host many of our South American and other foreign colleagues." For the first time some of the sessions were translated simultaneously, both from English into Spanish and vice versa. Thus, many Latin American clinicians who had never been able to appear on our programs before gave presentations in their own language. In some cases these clinicians had been attending our yearly gathering but always in the role of spectators. On the other hand, translation from English to Spanish, which took place in some of the sessions, made for deeper understanding of the work being presented there. In those sessions in which there was no simultaneous translation, bilingual members were

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assigned to work with the moderators to encourage postpresentation questions or comments from Spanishspeaking visitors who otherwise would have been reluctant to approach the floor microphones. Although the official words of welcome weren't delivered by President Uchin until the first Thursday morning session, convention activities actually had begun two days before. The A A E board gave its written and oral examinations; Drs. Harold Stanley and Gerald Kramer presented all-day continuing education courses; the trustees of the Endowment and Memorial Foundation and the members of the executive committee held their deliberations; and the commercial exhibits were set up. The Fellowship Reception on Wednesday evening brought the bulk of those in attendance together for the first time, and this was preceded by a special international reception to make the large number of visitors from foreign countries feel at home and among friends.

FIRST DAY--MOBNING Scientific S e s s i o n - - M o d e r a t o r : D a n i e l B. Green, chairman of

endodonfics, Medical Colleqe of Virginia, Richmond eJens O. Andreasen, oral surgeon and pathologist, Royal Dental College, Copenhagen. "Replantation of avulsed teeth."

Dr. Andreasen said that primary teeth should not be replanted. The problem, therefore, is limited to permanent teeth, the germ of which is in such close relationship with the primary tooth that its development could be interfered with in an attempt to replant the primary tooth. Although most textbooks state that replantation offers only a temporary solution, it is possible to have long-term results, as proved with cases of 40 years follow-up. To evaluate measures that could lead to long-term results, one must know what type of resorption is taking place. If it is of the benign-surface type, the definite feature is that it is always surrounded by normal periodontal membrane space. In inflammatory resorption, there is often diffusion of toxic products from an autolysed pulp into the periodontium. Pulp removal and calcium hydroxide introduced into the canal will stop the inflammation, and a new periodontal membrane will form. Replacement resorption is the most severe resorptive process. The resorbed tooth is replaced by bone, leading ultimately to ankylosis. In studies of the effect of the storage medium on replantation it was shown that dry storage resulted in much ankylosis; saline was a much better medium; however, saliva was the best. The recommendation was to keep the tooth moist and preferably in the oral cavity, instructing the parent or emergency service to place the tooth between

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the patient's lip and gingiva. Furthermore, it is very important that the replantation be performed immediately. Cleansing of the root surface must be done very gently and carefully with a saline-soaked gauze sponge. Endodontic therapy should be deferred for the sake of expediency. Splinting should be minimized to a period of about one week, reducing the possibility of ankylosis. At present, Dr. Andreasen is using an acid-etch splint. Ankylosis is not always a permanent condition. In 25% of cases it disappears spontaneously. A slight mobility of the tooth in the healing period will help eliminate small areas of ankylosis, and this is how nonsplinting helps. H e empirically recommends the use of penicillin, 2,000,000 international units, for three or four days. Despite the fact that there hasn't been a single case of tetanus reported after replantation, antitetanus precautions should be taken. With the treatment policies indicated here, failures are now limited to 50%. This is still a high rate of failure. 9 Gerald M. Kramer, periodontist and chairman of department, Boston University. "Endodontics and furcation therapy." Although the total periodontium is Dr. Kramer's bailiwick, the primary focus of his presentation was the preservation of the dentogingival junction at a level of 0 to 3 mm in an area that can be bacterially depopulated on a regular basis for those people who have a normal immunologic titer. Furcations do not qualify because basically they are culs-de-sac and are very difficult to depopulate by the average practitioner. They become, therefore, the bane of the periodontist's existence. Where the periodontium is deteriorating rapidly, it is sometimes necessary that the furcation area be made available for self-cleans-

ing, with endodontic therapy becoming a required part of the combined approach. In this the question always arises: What do I do first? There are frank periodontal furcations where the junctional epithelium has been migrating apically, leading to inflammatory disease, lysis of the fibers, and involvement of the furcation. Then there is endodontic furca development, in which autolytie changes take place in the pulp (perhaps caused by caries), and a sinus tract develops into the periodontium and causes lysis of bone in the furcation area. There is also the combined lesion resulting from instrumenting a large canal in the presence of a progressive periodontal deterioration going into the furca. Aberrations, such as enamel pearls and cementicles, are important in these situations as is occlusal traumatism, which causes changes in the bone not of an inflammatory but of a degenerative nature. It may be true that bifurcations can be maintained for years with nothing untoward happening, depending on the immunologic system. Total treatment planning is impossible without understanding the part endodontic therapy will play in the overall procedure. Which comes first, however, in the treatment proper? Hemisection, endodontics, or vital sectioning? In general, Dr. Kramer does not choose endodontics first because he is convinced that flaps and osseous healing do better on vital teeth. In his own experience with thousands of sectioned teeth, the success rate is very high when canals are obturated afterward. Furthermore, in maxillary molars where there are three furcations, one very often cannot know preoperatively which toot can be preserved. 9 Lei[ Tronstad, endodontic chairman, University of Lund, Malmo, Sweden. "Morphologic and physiologic basis for dentin sensitivity."

While the innervation of the dentin has been proven and disproven alternately during the last 100 years, there has never been a real disagreement with regard to the innervation of the pulp. Without doubt, this is due to the excellent work of Raschkow, published as far back as 1835, and it remains clear that sensory nerves are present near the dentin, between the odontoblasts, and in close contact with them. To explain the sensitivity of dentin, three theories evolved during the last century; no really innovative theories have developed since. The first theory is that dentin sensitivity results from direct stimulation of sensory nerve endings in the inner dentin. During the light microscope era, the uncertainty over this was a consequence of the argyrophilic nature of nerve tissue and the use of silver salts to disclose its presence. The collagen matrix of dentin also will, however, stain intensely with silver making it difficult to separate the two types of tissue. In 1960, Fearnhead was able to trace silver-stained fibers in dentin through serial sections to the pulp where he could show them originating from structures identifiable as nerves. R. M. Frank, some six years later, published the first electronmicrographs showing nerves in the mineralized part of the dentin. Note, in this connection, that Frank and others in this field have been able to observe nerves only in the most pulpal part of the dentin--in no case more peripherally than the inner third. Physiologic studies by Anderson and others, in which pain-producing substances such as acetylcholine, calcium chloride, and bradykinin failed to produce a reaction, also indicated that there are no nerves beyond the pulpal part of the dentin. Scott's electrophysiologic studies pointed in the same direction. If these

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receptors then are present only in the circumpulpal dentin, this cannot explain dentin sensitivity because it is known that one of the most sensitive areas is near the dentinoenamel junction, a part furthest away from the nerves. It was, in consequence, logical that a theory should arise assigning to the odontoblasts, whose processes are assumed to extend all the way to the enamel, the role of receptors transferring impulses to the nerves through synaptic connections. Two objections were proposed to the assumption that odontoblasts are of mesodermal origin: One is that in some animals the odontoblasts appear to develop from the neural crest, and it has been speculated that this may be the case in humans. The other rebuttal points to the way in which certain modified muscle fibers, certainly of mesodermal origin, function as receptors. Giving added weight to the arguments for this theory were studies showing the special relationship between nerves and odontoblasts in the odontoblast layer and the finding by Avery and co-workers of cholinesterase activity in dentinal tubules and thus the possibility of a receptor transfer mechanism there. The authors were not able to repeat their findings nor were other researchers in this area. Frank showed what he concludes are tight junctions between the cells, and his findings make it difficult to completely exclude the possibility that the nerves may be stimulated when something happens to the odontoblastic process. Nevertheless, the extension of the odontoblastic process right to the enamel has been assumed for more than 100 years, but it has never been shown; this is an essential condition if this theory is to explain dentin sensitivity. Dr. Tronstad's studies with the electron microscope indicate that what is 350

seen are not the processes but collagen fibers displaying the crossbanding typical of these structures. If it is true that the processes extend only a short distance into the tubules, this may explain why we can prepare deep cavities by using a gentle technique without damaging the odontoblasts. The third theory, proposed around 1900, suggests that dentin sensitivity may be explained on the basis of movement of fluid in the tubules. Some 15 years ago, Briinnstr/Sm picked up this idea and has been experimenting constantly ever since to obtain proper evidence. H e first concluded that many pain-producing stimuli also cause aspiration of odontoblasts into the tubules, and this was what stimulated the pulpal nerves. Langeland and K r a m e r both opposed this, each having shown earlier that there was not necessarily any connection between odontoblast aspiration and pain. BrHnnstr/Sm's later work stressed the speed of fluid movement in the tubules, which he calculated may reach a velocity of 2 to 4 mm/sec. In support of his hydrodynamic theory, he cited in vitro experiments in which there is fluid movement toward the pulp or away from it in response to temperature changes, air blasts, hypertonic solutions of sugar or calcium chloride, and application of blotting paper.

Endodontic R e s e a r c h Seminar, Graduate Student S e c t i o n - Moderator: S a m u e l Seltzer, c h a i r m a n of endodontoloc.ty, T e m p l e University, P h i l a d e l p h i a 9 Louis C. Peron, University of North Carolina, Chapel Hill. "Vital pulpotomy using variable concentrations of paraformaldehyde in rhesus monkeys." Encouraged by the relatively higher success rates of Formocresol over Ca (OH)2 pulpotomies, Dr. Peron decid-

ed to work with various concentrations of the active ingredient: 19% as taken from Buckley's Formocresol; 5% formaldehyde, suggested by Straffon, and Han and Loos, as allowing adequate fixation of tissue; 1% and 2% formaldehyde to determine the minimum necessary dose; and a dressing containing no formaldehyde to serve as a control. Zinc oxide and paraffin oil were used to form a thick, homogeneous, nonsetting pulpotomy dressing. This can cause massive, chronic inflammation of the pulpal tissue with subsequent internal resorption of the root canal. In some instances the result will be a repair as evidenced by minimal inflammation and incomplete dentinal bridging. Addition of low concentrations of paraformaldehyde to this paste results in some attempt at dentinal bridging, but internal resorption is still a possible undesirable feature. Higher concentrations of paraformaldehyde inhibit internal resorption but prevent dentinal deposition as well. 9 Stephen M. Littman, University of Maryland, Baltimore. "Evaluation of root canal debridement techniques." The root canals of 90 extracted mandibular premolars were mechanically instrumented by three different techniques by three clinicians. A radiopaque material, Hypaque-M, 90% (a solution of sodium and megluminr diatrizoates), was placed into the root canal, which was radiographed both before and subsequent to instrumentation. Debridement efficiency was evaluated on the basis of the amount of radiopaque material removed. Operator performance seemed to have more significance than the technique used. The use of a radiopaque material as a means of evaluating root canal debridement appears worthy of further investigation. 9 Samuel J. Mizrahi, professor of endodontics, San Carlos University,

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Guatemala. "A scanning electron microscopic study of the efficacy of various endodontic instruments." This somewhat related study was carried out while Dr. Mizrahi was a graduate student at Temple University, Philadelphia, puzzling over the disagreement in the literature concerning instrument effectiveness. Only anterior teeth were used in the study, five teeth for each instrument: the Giromatic broach, the Giromatic Hedstroem file, the regular file, the regular reamer, and the regular Hedstroem file. Assessment of cleansing effectiveness was made by scanning electron microscopy. The worst results were found when the Giromatic broach was used. Regular files and reamers used in combination gave the best results. This may be because twice as much cleaning and irrigating was done, but even so, a very clean canal was never produced. Some tissue was always left behind. 9 Richard E. Anglin, University of N o r t h Carolina, Chapel Hill. "Cobalt radiation and pulpal manipulation in monkeys." Various authors have recommended root canal filling as preferable to extraction in the postradiation period. This appeals to common sense but there is no histologic support in the literature, and it is needed now. Highenergy sources such as cobalt have changed attitudes on the outmoded decision for prophylactic full-mouth extraction before radiation therapy to avoid radiation caries and subsequent osteoradionecrosis. This study in monkeys, attempting to simulate human clinical experience, supports the recommendations favoring root canal fillings in irradiated patients. It must be borne in mind, however, that these were not necrotic cases. 9 Wayne H. Pulver, Harvard, School of Dental Medicine, Boston. "Immune components in human dental pulp and

periapical lesions. (A prize is awarded for the best graduate student paper; this year the judges, Drs. Louis Grossman, H a r r y Blechman, and I. B. Bender, awarded it to Dr. Pulver.) The purpose of this study was to examine normal and inflamed pulp tissue and periapical lesions for the presence of humoral immune components. This would be indicative of possible immunologic hypersensitivity reactions, which recent evidence has suggested may play a role in the pathogenesis of pulpal and periapical disease. A direct immunofluorescent technique was used in which a dye such as fluorescein can be linked to antibodies. These labeled antibodies combine only with their corresponding tissue antigens, and this can then be visualized in the ultraviolet microscope through the emission of fluorescence. By using labeled antiserum to various immune components such as IgG, IgA, IgM, and IgE as well as C-3, a complement component, their presence in tissue can be detected. In these tests no immunoglobulincontaining cells (ICCs) were found in normal human pulp tissue. In contrast, ICCs were found in inflamed pulp tissue with I g G predominating and some IgE also observed. In periapical lesions, both cysts and granulomas showed a high degree of IgG fluorescence and some IgE cells. Cysts displayed a higher incidence of IgA ceils, recalling the findings of the English investigator Toller. Periapical scars were devoid of any immunologic components, and no plasma or mast cells were seen. The implications of the findings include the possibility that in the presence of suitable antigenic stimulation, IgE cells can interact with mast cells to cause disruption and liberation of vasoactive amines (histamine and slow-reacting substances). Bradykinin, a pain producer, is formed from the plasma elements and

may lead to vasodilation, increased capillary permeability, and leukotactic chemotaxis as well as pain. How this immune response is activated and its role in the perpetuation or resolution of endodontic infections remain to be answered, but it is hoped that this work will help to generate further thought and research. 9 M a h m o u d Torabinejad, University of Washington, Seattle. "Antigen antibody induced periapical lesions." Referring to the previous paper, Dr. Torabinejad announced that he wouid continue the speculation and had taken one further step. His study was aimed at developing a model for examining bone loss caused by immune complexes in the intact animal. This induction mechanism in periapical lesions specifically has not been investigated. Preformed immune complexes are shown for the first time to induce a rapidly evolving periapical lesion characterized by accumulation of inflammatory cells typical of an Arthus' reaction. The results indicated that simulated immune complexes induced bone resorption with collagen loss in all animals injected, and that the lesions appeared within seven days of injection and increased in size on reinjection. The predominant inflammatory cells observed were neutrophils, and the resorption was mediated by osteoclasts. These seem to be activated by prostaglandins. This study showed, by the use of the antiinflammatory drug indomethacin, which inhibits their synthesis, that prostaglandins may play a major role in bone resorption. The tooth periapex is a convenient site to study this in vivo. 9 William A. Shelton, Boston University. "Viscosity of gutta-percha and its flow rate." This study was carried out to determine the flow characteristics and moldability of various commercial brands of gutta-percha, balata, and 351

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trans-1, 4 polyisoprene (the chemical name for gutta-percha, used by manufacturers to make it synthetically). It was decided to test viscosity by the use of an extrusion capillary rheometer, a method that most closely approximates the root canal filling technique. The results supported the concept of increased crystalline orientation in gutta-percha caused by thermomechanical preparation of the material. Elongation tests showed the small rods to be about 35% more brittle, less moldable, and stiffer than the large ones. Methods used in heat treatment and manipulation by commercial processors have a decided influence on the physical properties of the finished cones. Old Mynol cones are the most brittle; new Mynol cones are the least brittle.

Projected C l i n i c s ( S p a n i s h w i t h Simultaneous Translation-Moderator: Carlos Del Rio, Institute of Dental Research, Walter Reed Army Medical Center, W a s h i n g t o n 9 Juvenal Gonzdlez Leon de Peralta, Lima, Peru. "Apical impression filling technique." In this filling technique, a master gutta-percha cone is first fitted a minimum of 2 m m short of the measured length of the instrument used in the biomechanical preparation. Grossman's cement is placed before the impression is taken, but very little is used and at normal consistency. Once the cone has been well adapted in the apical third, forming a subapical stop, it is not removed. Then both lateral and vertical condensation techniques are used. This method should be used only in canals prepared to at least a size 55 to 60. In very long roots or ones with wide, immature foramens, it has to be used with great caution. Much better

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adaptation in the apical level than the standard cone is claimed and, also, a better filling of wide accessory canals. 9 Oscar Maisto, Buenos Aires. "Apical and periapical repair following endodontic treatment." The ideal way of checking successful results is by histopathologic studies, but this research approach is, of course, out of the question as a routine procedure in practice. Practitioners, therefore, have to rely on the radiograph, but clinical signs and symptoms must go hand in hand as indicators. The biologic sealing of the root apex is the last step in the reparative mechanism after endodontic therapy, and it consists of closure of the foramens by a precipitation of secondary cementum. W h e n the pulp ceases to perform its function as an organ, there is no longer a reason for the communication between the apical periodontium and the root canal to exist, and it must be obliterated. The most favorable condition, although it can happen even when conditions are not favorable, is when at the end of treatment the root apex is free of filling material and the rest of the root canal is permanently obturated. Research over the years in humans and animals shows that best results were obtained with fillings short of the apex. Tubes implanted in animals by various researchers tend to support this. In light of the natural tendency of the periapical connective tissue to make its own root canal filling when the pulp function is annulled and taking into account all of the serious research work quoted, one has to reject the old concept that only the hermetic filling of the entire canal leads to an acceptable repair. 9 Daniel Silva-Herzog, Mexico City. "Impression technique for filling canals." Dr. Silva-Herzog gave credit to fellow Mexico citizen and A A E charter member Dr. Enrique Aguilar for ere-

ating this technique, which finds its proper use in cases of incomplete foramens or where the canal has to be prepared to a size of at least a no. 60 instrument. In this type of case, one runs the risk with other techniques of overextending the filling material. This is considerably lessened with this method because of the close adaptation in the apical third. Thus, lateral condensation can be carried out and a proper seal realized both in length and in diameter. A gutta-percha cone of the same dimensions as the measuring file is flattened to nail-head form at its fine end with a warm spatula. The end then is dipped in xylol for three to five seconds and is carried immediately to place in the canal, thus taking an impression of it. After removal of the cone, it is coated with the sealer preferred, pressed back into place, and lateral condensation effected.

Projected Clinics - - Moderator: Jack Landsberq, Miami, Fla, chairman of entire projected c l i n i c s section 9 Robert V. Weissman, Fairlawn, NJ. "Filling with titanium in fine canals." The claim is that this is the newest, safest, and easiest method of filling small canals because titanium is reputed to be the safest biologic material available today. It is safer than pastes or gutta-percha. It is also safer clinically because it avoids excessive loss of good tooth structure for nonbiologic reasons, thereby reducing the chance of vertical fracture. This chance is reduced also by the elimination of forceful gutta-percha techniques. Because this material can be acceptably introduced into fine, curved canals, preparation in those cases can be kept to a size 20, thereby preventing such untoward results as "zipping" or transporting the foramen. With the

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use of nonsilver AH26, a three-dimensional filling is obtained and good apical seal established. 9 Frank T. Wais, Leesburg, Fla. "Practice aids in endodontics." Dr. Wais showed modifications of surgical and endodontic procedures, making for greater simplicity and efficiency. He also demonstrated the use of various instruments not ordinarily considered endodontic in nature that could be rewarding to the users. One of the most interesting innovations is an emergency system for processing radiographs rapidly and effectively in case of trouble with the regular darkroom setup. 9 Manuel I. Weisman, Augusta, Ga. "Acid-etch splinting of luxated teeth." A n emergency-prepared tray arrangement was described. After local anesthesia and suturing of lacerations, the teeth are repositioned and pumiced. Then, a 0.0215 X 0.028 rectangular wire is bent to conform to the middle third of the arch. Calcium hydroxide is applied to any dentin exposed by fracture before application of 60% H3PO 4 to the middle third of the labial enamel for 30 seconds. This is applied with a drop of etching gel and then neturalized by washing with a sodium bicarbonate solution. The wire is positioned in the middle third of the labial surfaces and secured at its two ends with wax, after which Orthomite IIS adhesive is painted over the wire and etched surfaces only. In three to four minutes the plastic sets and the wax is removed from the ends and replaced with adhesive. The wire remains in place until the case is completed, and rubber dam placement, vitality testing, and all aspects of endodontic therapy can proceed normally. 9 Yury Kuttler, Mexico City. "Analysis and comparison of root canal filling techniques." More than 100 different techniques and close to 270 materials have been

used. Over the years, three differing apical limits have been advocated: overfilling, under filling, and the dreamed-of "exact" filling. Techniques can be classified into three groups: cement with a rigid cone or cones; condensation techniques; and antiseptic pastes. All materials, whether liquid, paste, or solid, act as foreign bodies and are mild, medium, or severe irritants to the metaendodontic tissues. F o u r postulates were advanced for the correct filling of the canal. Only a controlled precision and biologic technique that fulfills all of them can achieve a high degree of success. The majority of root canal fillings carried out with all three groups of techniques are underfillings or overfillings and thus unacceptable. Luncheon with Culture 9 Fernando Ortiz-Monasterio, profes-

sor of plastic surgery, graduate division, Medical School, Universidad Nacional Aut6noma de Mexico. "Panoramic view of orofacial deformities in Mexico." A great variety of slides was shown depicting examples of ancient Mexican culture. Among these were skulls from the M a y a n civilization, displaying filed teeth and teeth filled with jadite and hematite inlays that were placed with precision techniques, the details of which are still unknown. However performed, these inlays have remained in place for over 1,000 years, and most of them, as proved by radiographic study, were prepared to exactly the proper depth. Explaining that their beautiful ceramic works were representations of all aspects of their life, Dr. OrtizMonasterio showed a great number of pieces from his own collection in which different disease states are evident. Included among these were such interesting conditions as the TreacherCollins syndrome (mandibular facial dysostosis) ; prognathism; various clefts, including an Olmec piece dat-

ing back to 1500 Bc that gives a clear representation of a bifid nose and central cleft; and hunchback. These and other deformed people were considered important in their culture as being different from ordinary men and closer to the gods. Dr. Ortiz-Monasterio finished his talk with a description of the work presently being done by his mobile unit team, which travels to remote areas of the country. Among other things, members of the unit are teaching physicians in far-off places what can and should be done properly and early; where they can refer patients for free care in Mexico City institutions; and how to apply as recruits to join the multidisciplinary teams composed of surgeons, dentists, orthodontists, speech therapists, and psychologists. FIRST D A Y - - A F T E R N O O N Scientific Session

-- Moderator:

Howard Martin, Silver Sprinq, Md

9 Stephen Cohen, San Francisco. "Another view of the 'simplified' endodontic method (a critical analysis)." The development of the N2-type pastes from their beginnings up to the present was traced. Dr. Cohen analyzed some of the chemical constituents of the following pastes: N2 itself, RC2A, RC2B, RETB, and RC2 White. Almost all of them contain lead oxide, phenylmercuric borate, corticosteroids, and, of course, formaldehyde. The bulk of the composition is zinc oxide-eugenol. He also reviewed the dentolegal hazards in the use of these pastes. He emphasized that the F o o d and Drug Administration has categorized all of these as "nonapproved." They are banned in several European countries, functionally banned in California, and completely banned in Maryland. As a result of the testimony that Dr. Cohen

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and others delivered before Congress and the F D A in 1975, the latter agency took decisive action to enforce compliance with federal drug laws. Dr. Cohen, as moderator of the second part of the session, introduced "May I have the first slide please? (revisited)." (This was a repeat by popular demand of one of the best-received presentations at the 31st meeting of the A A E in San Diego, Calif.) Dr. Richard C. Burns, San Mateo, Calif, dealt with the use of graphics in the preparation of good visual lecture illustrations. He covered the use of transfer materials, both letterface opaque and color shading. Composition and good form were stressed in the discussion of design and layout. He delineated many art forms available that do not require the artist's permission. He explained the use of cutouts and old existing lithographs for title slides, and he ended with a discussion on making slides tell a story. Dr. John Sapone, San Francisco, discussed the slide essay, and he related his method of composing and ordering his slides in such a way that they take on their own logical sequence in what is essentially a story form. The material is all there in files and patient records, but too often one fails to appreciate how well it can be organized into an interesting and informative recital. He showed how to gracefully conelude a lecture of concentrated endodontic material with a mini-essay on well-selected subjects related both to endodontics and to the background of the audience. A variety of acceptable subjects was illustrated, but he advised strongly against the use of slides of nudes and other sexual materials for this purpose. Dr. Noah Chivian, West Orange, NJ, continued his examination of the title slide, a subject that had provoked

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so much interest at the meeting two years ago, giving a wide-ranging variety of approaches to its preparation. He also went further into his ESP (eclectic slide preparation) series, elaborating on multiple projection techniques, progressive disclosure and continuity, and appropriate slides to indicate the end of a series.

Endodontic R e s e a r c h Seminar, Non-cjraduate Student Section - Moderator a n d Chairman: Melvin G o l d m a n , Worcester, M a s s 9 Al/onso Moreno, Monterrey, Mexico. "Thermomechanical softened gutta-percha technique." An approach to the attainment of a three-dimensional obturation of the root canal system based on the ultrasonic apparatus Cavitron was discussed. This was an in vitro study in which 20 extracted teeth were used, ten of which were root filled by lateral condensation of gutta-percha, the the other ten by the experimental technique. After the teeth were stored in saline solution for seven days, they were dried, covered with nail enamel, and immersed in iodine 131; autoradiographs were obtained with Kodak Royal pan film. The teeth were sectioned under a spray of Freon, a refrigerant used to avoid heating and changing the gutta-percha. The results indicated a mean of 1 mm of percolation with the new technique as against a mean of 2.5 mm with lateral condensation. A greater degree of condensation also was demonstrated. 9 Ronald A. Sproles and Marwan Abou-Rass, University of Southern California, Los Angeles. "An anatomical investigation of pulp chambers using silicone rubber." Dr. Sproles outlined a study of 235 maxillary and mandibular first and second molars in which a modifica-

tion of the Davis, Brayton, and Goldman vacuum injection technique of silicone rubber was used to form molds of the chambers. The significant findings of the study were as follows: a newly discovered cervical pulp horn was present in 79% of maxillary molars and 65% of mandibular molars; volume of the coronal pulp chamber decreased with age but was not affected by caries or restorations present; the central occlusal pit was found to be in the center of the roof of the chamber in 70% of the specimens, and when this varied it varied mostly to the mesial; bifurcation and trifurcation accessory canals appeared in 10% of maxillary molars and 3% of mandibular molars; extramesiobuccal canals were present in 62% of maxillary first molars but also in 55% of maxillary second molars; total volume of the chambers compared with the teeth was greater for maxillary than mandibular molars; there was significantly less enamel and dentin thickness over the mesiobuccal cusp for all molars; the general occlusal outline in maxillary molars was rhomboid, 70%, and triangular, 30%, with the apex toward the palate; mandibular outline was rectangular and slightly wider mesiodistally; and there was a greater enamel and dentin thickness mesially and distally than buccally and lingually in the chambers of all molars. 9 Louis I. Grossman, University of Pennsylvania, Philadelphia. "Physical properties of root canal cements." Physical properties of root canal cements have been less thoroughly investigated than the biological properties. AH26, Diaket, Kerr sealer, Mynol, N2, N2 without lead teroxide, Procosol, Roth, RC2B, Tubliseal, and zinc oxide-eugenol were tested. They were examined for particle size, flow, setting time, adhesion, and peripheral leakage. Zinc oxide-eugenol showed no adhesion within the limits of this ex-

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periment. Dimensional change of leakage was demonstrated by postsetting application of safranin red, in the following order: the best was Diaket, followed by Kerr, Procosol, Tubliseal, Roth 801, Roth 811, RC2B, N2, N2 no-lead, AH26, Mynol, and ZOE. 9 Oscar A. Maisto, Buenos Aires. "Clinical and radiographic investigation of 150 endodontic implants. For experimental purposes, implants were placed even where they were contraindicated. The patient had to authorize the experiment, knowing the possibility of failure, and in some instances implants were placed in teeth destined for extraction. Use of the endodontic implant requires exhaustive diagnostic procedures before a decision is made to use it, and indications and contraindications must be determined in each particular case. 9 Lawrence B. Goldman, Tufts University, Boston. "Study of Hydron as a root canal filling material." This was a continuation of work reported on at the last two annual meetings when histologic evidence from primate studies was shown and physical characteristics listed. The latest work with this hydrophilic material (a polymer of hydroxyethyl-methacrylate to which barium sulfate has been added for radiopaeity) has been carried out on clinic patients after obtaining approval from the Human Investigation Research Committee of the Tufts-New England Medical Center. Dr. Goldman presented a brief review of the histologic evidence of both biocompatibility and penetration into the dentinal tubules. An X-ray microprobe analysis quantitated and located the presence of barium sulfate within the periapieal tissue cells, confirming what had been deduced from light and scanning electron microscope visualization. In two clinical cases, the delivery system was demonstrated. It takes only 10 to 15 seconds to actu-

ally obturate the canal, and the method is easily applied in multirooted teeth. 9 Alan Nevins (last year's prize winner at the graduate student section of the research seminar), New Britain, Conn. "Revitalization of pulpless open apex teeth in rhesus monkeys, using collagen-calcium phosphate gel." This report represented investigations carried out at the Nassau County Medical Center, NY, under the direction of Dr. Richard Moodnik with the collaboration of Drs. Francis Finkelstein and Bernard Borden and Mr. Robert LaPorta. Dr. Nevins, who is now in a new position at the University of Connecticut Health Center, described a revitalization after pulpal debridement and placement of a collagen-calcium phosphate gel in several open apex teeth of juvenile rhesus monkeys. A highly viscous solution of tropocollagen, calcium, and dipotassium hydrogen phosphate, buffered to a pH of 7.4, gels within the root canal in contact with periapical bone. During gelation, tropocoUagen molecules polymerize to form native collagen fibrils, which are chemotactic for macrophages and fibroblasts and serve as a physical matrix for fibroblast migration. Calcium and phosphorus ions within the gel form hydroxyapatite crystals, which induce the mineralization of connective tissue ingrowth. Histologic examination of several teeth treated with this technique at 12 weeks showed canals filled with hard tissue that was cellular and vascularized. Fibrous connective tissue also was present and formed a periodontal ligamentlike structure at the apex. 9 Marvin A. Gross and Donald Morse, Temple University, Philadel-

phia. "Acupuncture and endodontics." Dr. Gross began with a brief, historical review and a listing of the various theories that have been consid-

ered possible explanations of how acupuncture works. In the current study, ten teeth, all with vital pulps, were treated endodontically, and an attempt was made to obtain analgesia with acupuncture. Both dental and nondental acupuncture points were used; after needles were inserted, both electrical and manual twirling methods were used. The results showed that in 80% of the cases some form of analgesia was achieved. It may be that in some patients with a history of allergic reactions to anesthetic solutions, acupuncture could be tried as an alternative procedure. SECOND

DAY--MORNING

Scientific Session -- Moderator: Donald Arens, Indianapolis

Parker E. Mahan, professor and chairman, department of basic dental sciences, University of Florida, Gainesville. "The pathophysiology of facial pain and vascular pain that mimics pulpaI pain." Dr. Mahan predicted that in the next five to seven years scientists are going to learn more about pain than they know today, and this is owed to the notoriety of acupuncture, which stimulated research in pain. Actually, a few years ago it was thought that a lot more was known about pain than is known now. There was a simple theory--the specificity theory of pain perception--that taught that a primary sensory neuron has its receptors somewhere such as in the tooth pulp or the mucosa. It has its cell body outside the central nervous system (CNS) in a location like the gasserian ganglion, and its proximal process projects into the CNS. Soon after entering the gray substance it synapses with a secondary neuron, crosses the spinal cord to the lateral spinal thalamic tract, goes to the thalamus, and synapses with a third neuron. The third neuron projects to the somato-sensory cortex, and when 9

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nociceptive stimulation out in the periphery activates the primary, secondary, and tertiary neurons, the patient perceives pain and suffers. This theory became obsolete when it was found that it could not explain many pain phenomena and when, for example, it was discovered that many lateral spinal thalamic tract fibers never reach the thalamus but disappear into the reticular formation, the brain stem, or the cord. In 1965, a psychologist and a neurophysiologist, Melzack and Wall, devised the so-called gate control theory, which had as one of its major contributions the concept of antagonism between large and small fibers. According to this concept, anything that can be done to increase large fiber input relative to small fiber input will tend to obtund pain. Dentists for years have been working in accordance with this without even knowing it. F o r instance, they squeeze the patient's lip, increasing large fiber input from pressure and touch, at the moment of inserting the needle. The theory also went far in explaining such things as placebo effect in that it postulated a central control so that the central state, mental condition, degree of anxiety, etc, would indeed alter or affect pain perception. The modern theory that has replaced this is Frederick Kerry's central inhibitory balance theory, which holds that we have a more complex anatomy than was diagrammed by Melzack and Wall; that there are actual divisions in the small fiber system; and that within this system itself we have inhibition. The gate control concept of inhibition is still present in the new theory, and there is much more anatomic evidence at present that these connections do exist. In talking in more detail about the head and neck, he pointed to the frequency of innervation of the periosteum and mucosa over the angle

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of the mandible by the upper cervical nerves, C-2 and C-3. As a result, cardiac or anginal pain may in fact radiate to the left angle of the mandible rather than entirely to the left arm and wrist. We have a lot of overlapping of innervation in the head and neck, and we see a lot of peculiar patterns that may not be true referred pain but rather a result of this complex overlapping. One area of great overlapping is the pinna of the ear, where the upper cervicals, the trigeminal, and the seventh, ninth, and tenth cranials all come together. Interestingly enough, this is a much-used acupuncture point. Acupuncture can indeed represent large fiber activation, and it can sometimes have lingering effects. He cited some examples of use of acupuncture or acupuncture-type approaches or electrical stimulation to eliminate tic-type pains and to inhibit perception of recurring or chronic pain. 9 Jens A n d r e a s e n . "Luxation of primary and secondary teeth diagnosis and treatment," (Lecture 2). The crucial aspect in treatment of a luxated primary tooth is that if one destroys the cervical loop, one destroys the potential for formation of the permanent tooth. A little later in development, one has to be concerned with Hertwig's epithelial sheath. If one disturbs that, there is no chance of completing root development. One also must be concerned about the reduced enamel epithelium because it is responsible for final mineralization of the enamel. When a primary tooth is intruded in its socket with its apex in a labial position (away from the permanent tooth germ), continued observation is in order. If its apex is in actual horizontal or palatal position (against the tooth germ) it should be extracted. In the first instance, however, there can be complications because

the intruded tooth's crown is covered with plaque, and this can easily lead to acute inflammation. If the young patient returns with a high fever and signs of inflammation, this is very destructive to the underlying tooth germ; therefore, these primary teeth should be removed immediately. One of the theories put forth to explain eruption says it depends on pulp vitality, but this is false. A good number of intruded teeth will reerupt with pulpal necrosis, and under those circumstances they should be removed. However, the diagnosis of these necrotic pulps is very difficult, and pulp testing is of limited value. One has to learn to interpret other signs such as radiolucent zones, size of pulp chamber, and gray discoloration. In adults, the intruded necrotic teeth tend to stay in their abnormal positions, and one m a y have to use orthodontic means to reposition them. In those cases where extraction is indicated because the primary apex is dislocated palatally, contacting the permanent tooth germ, the extraction must be done very carefully, especially when elevators are used. They can easily be forced into the follicle. If the primary tooth is extracted very early, there will be about a year's delay in eruption of the permanent tooth. If it is extracted very late, the permanent tooth will erupt prematurely. This is information one needs to give the parents. They will too often consider esthetics to be the most important element and will plead for a conservative approach. However, one has to be concerned not with the preservation of just the primary tooth but with the entire dentition, and one must not let his good judgement be unduly influenced by the beauty of the primary dentition. 9 L e i / T r o n s t a d . "The use of calcium hydroxide in endodontie therapy," (Lecture 2). Calcium hydroxide is thought of as

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a new material, but actually Hermann introduced it around 1910 and wrote it up in the first edition of his book in 1920. His original idea was to use it as the permanent root canal filling, not realizing it is resorbable. In Zurich, Hess, famous among endodontically oriented dentists for other reasons, saw certain possibilities with the substance as a pulp-capping agent. It is because of this that it has survived. This pulp-capping procedure, with its superficial necrosis of tissue, is well known but it is not too well understood. Why, for instance, doesn't this reaction continue so that the whole pulp becomes necrotic? The inflammatory reaction is actually mild, and then at the border zone between the necrotic and vital areas the familiar dentin bridge forms. Is this a reaction caused exclusively by Ca(OH2)? Certainly not. Many drugs can induce dentin bridge formation, an illustration being the work of Eda (1961) in Tokyo, capping pulps with magnesium oxide. This drug stimulated the formation of a bridge, but then the pulp died. With Ca(OH2) healthy pulps are achieved in 70% to 90% of cases, but there are still practitioners who try this and get very poor results. There are two reasons for this: First, in diagnosis the pulp has to be absolutely free of inflammation if capping is to succeed. The second is failure to obtain and maintain a seal against saliva and microorganisms from the oral environment. In the case of a fractured incisor, neither simple capping nor placement of a plastic crown form will keep the seal intact. The Tronstad method is to drill a tiny cavity with a sterile bur. With this technique the practitioner waits for bleeding to stop, washes with physiologic saline, applies C a ( O H 2 ) , and seals with ZOE. If both of these conditions are met properly, size of exposure is of no consequence. The

treatment can be looked on as permanent. On the other hand, pulpotomy, in which bridging is achieved in the same way, is a temporary treatment. The patient often comes back several years later with periapical pathosis and a calcified canal. The advantage of the use of Ca(OH2) as an intracanal medication between visits in pulpectomy cases is that the canal is not left empty for tissue fluid and ingrowing granulation tissue to enter. The endodontist can consequently schedule his appointments at his convenience and not be under pressure to have the patient return quickly, to avoid trouble. The necrotizing effect on pulp tissue is very advantageous in internal resorption because repeated applications will necrotize all of the tissue, and this will be visible radiographically. After each application, the radiograph will show the paste filling more of the resorbed area. The outstanding feature is its use in nonvital cases and in the healing of periapical lesions. Many practitioners are now postponing the final obturation with guttapercha until healing is complete. Other situations where the material has proved itself are blunderbuss canals; external resorption; fracture (particularly where the fracture line separates a necrotic coronal pulp from a still vital apical portion); and the root resorption seen in luxated teeth. It has been demonstrated that for resorption to take place there must be enzymatic activity in an acid medium. The success of Ca(OH2) in countering this could, therefore, be partially explained on the basis of its very high pH. There has been much speculation as to what happens to the material left in the canal. Present thinking is that it is converted into CaCO3. That being the case, perhaps in its various intracanal uses, it should be changed

frequently to prevent this conversion and loss of effectiveness. L a t i n American S e c t i o n m Chairm a n : Jose O y n i c k , M e x i c o CityModerator: Enrique Basrani, Buenos Aires

Angel LaSala, Maracaibo, Venezuela. "Endodontic problems in molars." The first problem scrutinized concerns proper access so that discovery, preparation, and obturation of the several canals will be facilitated and a proper foundation retained for subsequent restoration of the tooth. Mandibular molars should have a trapezoidal access o p e n i n g - - n e v e r an isosceles form or the widely advocated cusp-to-cusp length on the mesial. On this long side, the opening should extend from the mesiobuccal cusp only to the central fossa or slightly further lingually. Maxillary molars should have triangular access cavities joining the orifices of the canals. The opening of the distobuccal canal should always form an obtuse angle. Irrigation was the second problem considered. N o matter how fine the needle of the syringe used in usual irrigating techniques, the solution will not reach apically; therefore, filings, debris, and clots will remain. The method recommended is to place fine, absorbent points the full length of the measured canal. Drops of irrigating liquid deposited after they are in place will be drawn apically by capillary action and by the hydrophilic properties of the paper point. The point swells when wet so that it will pull out debris with it when it is removed. The third problem concerned surface tension. If the canal walls are not left in ideal states from this standpoint, no obturation technique will provide an adequate seal. To overcome this difficulty, both anionic and cationic detergents and volatile solu9

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tions can be used. Just before obturating, ethyl alcohol and chloroform are used with the paper point technique in the canals. The final problem was that of being able to visualize the number, course, and interrelations of the various canals in posterior teeth. The solution lies in the taking of multiple radiographs, with a change of horizontal angulation of 15 ~ to 30 ~ toward the mesial or the distal. 9 Antonio Rothier, Rio de Janeiro. "Antibacterial efficacy and cytotoxicity of three root canal sealers." (In the unfortunate forced absence of Dr. Rothier, Dr. Louis Grossman read his paper and gave credit to Drs. Leonardo, Lia, Paca, and Marten, who collaborated in the work.) The three sealers were AH26, FS paste, and N2. FS paste is a creation of a Colombian dentist whose initials make up the name, and it contains a high percentage of iodoform. The first part of the study tested their microbiologic activity against five strains of bacteria: Escherichia coli, Klebsiella, Staphylococcus aureus, Bacillus subtilis, and Streptococcus viridans. The results showed that AH26 has a low antimicrobial activity; N2 showed great antimicrobial power; and FS occupied an intermediate position. The second part of the investigation dealt with cytotoxicity, all the materials behaving as irritants to subcutaneous connective tissue throughout the experimental period. FS and N2 pastes displayed the most irritating potential, and abscesses frequently were found initially. AH26 showed the best biologic tolerance. 9 Jose Oynick, Mexico City. "The clinical and histological evaluation of a new material for retrofilling." Amalgam has an irritating potential because of its mercury content and the corrosion factor. With ideal conditions for retrofilling, it works and seals well. When conditions are not

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ideal, cases that may look good over the years suddenly deteriorate. The reason for this may be the voids, shown in Moodnik's scanning electron microscope study, which could harbor bacteria and irritating products. Encouraged many years ago by Nicholl's work with ZOE, Dr. Oynick began a search for a material of superior biocompatibility. The search culminated when he found Stailine Super EBA cement, recommended for temporary and permanent cementation of fixed prostheses. The powder contains ZnO, 60%; SiO~, 34%; and natural resin, 6%. The SiO2 and the resin make the set product practically nonresorbable. The liquid is ethoxybenzoic acid, 62.5%, and eugenol, 37.5%. After 12 years of use, the clinical success is impressive, but because there are no proper controls as yet, percentages are not mentioned. Radiographs taken almost 12 years later show no change in the material's shape, indicating that resorption is no problem. Scanning electron microscope studies were shown that confirmed the fact that there is excellent adaptation with Stailine and that collagen fibers are deposited on it and within it. This points to strong indications for its use in perforations and external resorption.

Luncheon with Leu~,~nq The format of the "Tale with ale" sessions at the New Orleans meeting was followed. About 17 rooms were occupied, and the subjects presented ran the gamut of endodontic interest: instruments, gangrenous pulp, drugs, research, practice management, and dental education. Lunch was served buffet style.

SECOND DAY--AFTERNOON Audiovisual Presentations Chairman: James E. Ainley, Orlando, Fla

Four films were shown in the course of the afternoon. Two were films of Harold Stanley, University of Florida, Gainesville: Human Pulp Response to Operative Dental Procedures and The Biology o[ Pulp Capping Procedures. The other films were The Warm Gutta-Percha Technique, Herbert Schilder, Boston University, and Endodontic Emergency Treatment, Franklin Weine, Loyola University, Chicago.

Endodontic Research Seminar, Non-Graduate S t u d e n t s Moderator: Richard Moodnik, New York 9 Arthur Panella and Marwan AbouRass, University of Southern California, Los Angeles. "Study of the relationship of the mandibular canal to the apices of the mandibular second bicuspid, first molar, and second molar in dried human mandibles." During treatment of mandibular posterior teeth, the contents of the mandibular canal may be traumatized by instruments, medicaments, filling materials, and so forth. The radiograph, the only tool, gives a twodimensional representation of a threedimensional object. From various parts of the world one reads reports of fillings placed into the canal or into the mental foramen. The most significant finding in this study was that the long axis of the tooth passes through some portion of the canal in 61.3% of the specimens. An endodontic implant, therefore, placed through the apex and into the bone has a 61.3% chance of impinging on some part of the canal. Furthermore, the canal is not a solid bony tube. It is more like cheesecloth, perforated in a number of places. For that reason, it's easy to pass an instrument unknowingly through one of these perforations, and this must warn one, again, against overinstrumentation and overfilling. 9 Donald Morse, Temple University,

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Philadelphia. "Use of meditative study for hypnotic induction in the practice of endodontics." Of the 35 endodontic clinic patients serving as subjects, most were apprehensive and many were in pain. They were told to relax and to repeat silently a simple word such as "one" or "flower," during which appropriate suggestions of spreading, tingling numbness were given. When the spreading numbness had reached the facial area, deepening was effected with the "descending elevator" method. With most individuals, numbness could be directed to the tooth in treatment. With others, glove anesthesia had to be produced first with the imaginary "bucket of ice" technique, and then transferred. In six vital cases it was possible to complete all procedures without any local anesthetic. In the remaining 15, half the normal dose of lidocaine 1:100,000 was injected. The time from eye closure tO completed suggestions of numbness was seven to eight minutes. The meditative technique is effective and rapid, and can accomplish much in patient management. 9 Mr. Solomon Sorin (an engineer on the staff of the University of Pennsylvania Dental School, Philadelphia, he has appeared on these programs over the years with Dr. Seymour Oliet, presenting results of studies on properties of endodontic instruments). "Inhibition of the corrosive effect of sodium hypochlorite on carbon steel instruments." The investigation was undertaken to quantify Goldman's findings a year ago that presence of crushed tooth substance accelerates corrosion. This was confirmed, a n d it also was found that even a small amount of pretest corrosion will considerably increase corrosion products. It is, therefore, risky to use already corroded instruments. The study proved that inhibitors can significantly retard the cot-

rosion rate, although none of the 17 prevented it completely. Continued studies are planned, some on inhibitors, which are designed to minimize the dangers of instrument corrosion during use, and others to explore possibilities of accelerating corrosion as a possible means of removing broken instruments from blocked canals. 9 Melvin Goldman, Tufts University, Boston. " A new method of canal irrigation." Many papers in the last two years have proved with scanning electron microscope studies that a great amount of debris is left behind in the best-prepared canals. On the other hand, one knows that if one leaves a pulp in a 5% NaOC1 solution, it will dissolve away. Then why isn't the cleaning of the canals more effective? Perhaps too little attention has been paid to the method of irrigating; with this in mind it was decided to try a new type of needle for the irrigating syringe. The needle is sealed at the end and has perforations all along the sides to a distance of 10 mm. A dye solution of 0.1% toluidine blue was prepared, and 5 ml was flushed into two groups of extracted t e e t h - - o n e group being treated in the conventional way, the other group being irrigated with the new-style needle. Microscope examinations of cross sections of the roots showed that the new needle distributed the dye to the apex and the conventional needle only to the coronal third. 9 William E. Dowden, University of Connecticut, Farmington. "Sequenced response of pulpal, periapieal and periodontal tissues to bacteria." The pulp responds to the products of bacteria that have entered the dentinal tubules in dental decay long before the bacteria themselves have reached it. Bacteria do not colonize in vital pulp tissue, but if because of

their products inflammation begins in it, such cells as polyps, if present in large numbers, destroy adjacent host tissue. The areas of localized necrosis then can become colonized. This shows how inflammation can be a two-edged sword. When bacterial plaque, which has been moving apically on a root surface, destroying the periodontal ligament, reaches the foramen, pulpal tissue responds in much the same sequence as the coronal pulp to the bacterial attack of caries. 9 Oscar Maisto, Buenos Aires. "The use of calcium hydroxide." Calcium hydroxide is a drug that aids in the resolution of many varied problems, from the protection of the pulp in the face of destruction of the dentin to the obturation of canals with wide, open foramens. In studies done with Drs. Cabrini and Manfredi, it was determined that reparative dentin formation is stimulated by C a ( O H ) 2 applied to the cavity floor in indirect pulp capping. In studies of direct pulp capping, they found that in 8% to 13% of cases there was slight internal resorption but believed that this was the fault not of the material but of cutting or compressing the pulp. Corticosteroids have been accused, by such authorities as Baume, of inhibiting dentinogenesis; however, they deny this. In one of their studies, the steroid was applied to the exposed pulp for seven days, after which it was removed and replaced by C a ( O H ) 2 , with which they obtained successful bridging. They concluded that the inhibitory action of the steroid is transient. 9 Arturo Chavez y Chavez, Guadalajara, Mexico. " A comparison of intracanal medications." Camphorated paramonochlorophenol ( P M C P ) 1%, 2 % , and 35%; Cresatin; and a mixture of equal

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parts of Cresatin and PMCP were tested for their irritating potential. They were introduced into a rabbit's eye and left there for one minute. One percent P M C P showed very little irritating potential; 2% a little more; 35% highly irritating; the two-drug mixture less irritating; and plain Cresatin not very irritating at all. Bactericidal capacity was tested by disk sensitivity. Only 35% PMCP and the mixture of the two medicaments showed adequate potency. Because the mixture is less irritating, its use is recommended. Two diffusion studies indicated that none of the medicaments diffuse readily through canals; therefore, one must use them in sufficient quantity if proper results are to be attained. THIRD D A Y

MORNING

Scientific S e s s i o n - - Moderator: Edward O s e t e k , Great Lakes N a v a l Station, Ill 9 Parker Mahan. "The pathophysiolo-

gy of facial pain and vascular pain that mimics pulpal pain," (Lecture 2). One of the major problems with patients in pain is the determination of origin of the pain, whether it is mainly psychogenic or if there is dysfunction or pathologic conditions at the base. History and duration of pain are most important in this regard. The phenomenon of operant conditioning faces each practitioner. An operant is any action of a human organism that may be elicited by an antecedent stimulus, and operants are subject to influence by the conditions to which they lead, irrespective of the antecedent stimulus. A drug history is most important, and there are at least two types of tranquilizers that the patient might be taking which could produce facial pain that can mimic odontalgia or temporomandibular joint pain.

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Both the Compazine and the Haldol types can lead to extrapyramidal effects or pseudo-Parkinsonism, which can mean hyperirritability of the mandibular muscles and a bizarre, unilateral facial pain. On the other hand, Valium, in addition to being a tranquilizer, is also a muscle relaxant and is used in low dosage to diagnose true myalgia. Trigeminal neuralgia will appear most of the time on the right side and usually affects the lower two divisions of the nerve. The ophthalmic division is very seldom involved, which is the reverse of what happens in herpes zoster. In that condition, it is almost always the upper division that is involved. One explanation for the development of neuralgias in the cranial nerves but not in the peripheral nerves is the presence of big arteries around the cranial nerves. These become atherosclerotic and tortuous, and exert pressure on the nerve. This understanding is what led Dr. Peter Jannetta to develop his promising new treatment for trigeminal neuralgia, which is a decompression. He has treated about 400 patients at the University of Pittsburgh and says treatment has been successful. He makes an incision just above the mastoid process, finds the superior cerebellar artery, and inserts a small piece of sponge between it and the rootlets of the trigeminal nerve. In geniculate ganglion or seventhnerve neuralgia there is a lightninglike, on-and-off pain. It is not a severe pain problem, and surgeons try to avoid sectioning the nerve. The sixth, seventh, and eighth nerves all exit at about the same place; therefore, the eighth nerve could accidentally be cut and cause deafness, which would mean a serious medicolegal problem. Glossopharyngeal neuralgia is a severe condition, and in many instances it is combined with trigeminal neuralgia. These patients often won't

eat in public anymore or will turn away when they attempt to swallow food. They will often jam their fingers in their ears. This can now be explained on the basis of increasing large fiber input to obtund the excruciating pain. If a patient who is well under 40 years comes in with ticlike pain in the face, one must ask if the patient has noticed any weakness of the legs or morning fatigue and a need to sit down. This is very important because multiple sclerosis, when it affects the trigeminal nerve, will produce pain symptoms like trigeminal neuralgia. It is also very important that the dentist be prepared to quickly identify carotid system arteritis, also referred to as temporal arteritis. Palpation provokes fierce pain over the angular, the facial, and the carotid arteries. This is a giant cell arteritis, and the ophthalmic artery is the next to be affected; therefore, the patient will very quickly go blind. If the condition is treated soon enough, however, steroid therapy is miraculous. 9 John W. Harrison, Madigan Army Dental Center, Tacoma, Wash. "Issues and answers." Skimming over the current controversies in endodontics, Dr. Harrison elected to begin his discussion with irrigation of the canal. In the recent literature much evidence has been amassed decrying the use of full strength NaOCI, but this evidence, he says, is at best circumstantial. Surprisingly, in all of these articles no one has ever evaluated the use of full strength NaOCI in canal preparation. Experiments at Madigan showed that a reduced concentration of this solution will not debride as well as the 5.25% concentration, but the accusation has been made that at this strength it is too toxic. Testing saline, 5.25% NaOC1 alone, and 5.25% NaOCI used together with 3% H202, they found no statistically significant

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differences in interappointment pain. Another experiment showed no difference in interappointment pain, using dressings of Formocresol, camphorated paramonochlorophenol, or distilled water. Another controversy coneerns the sinus or fistulous tract. Which name should be accepted, what tissues constitute it, and what treatment should be adopted? The most important finding to come out of their studies, he believes, was that an epithelialized oral sinus tract does, in fact, exist. Now that its existence is known, perhaps researchers can proceed further and disclose its clinical significance if, in fact, it has any. Bacteremias caused by endodontic manipulations is a subject involved in controversy too, but unlike the other issues this one is not intraspecialty but interspecialty--between the endodontists and the oral surgeons. Their investigation confirmed an earlier study by Bender, Seltzer, and co-workers that bacteremia does not occur as the result of any endodontic manipulation confined to the canal. Indications are that endodontic therapy is a very safe procedure. 9 Birger Nygaard-Ostby, Oslo. "The old man and the p u l p - - a swan song." (Dr. Ostby was honored with the Louis I. Grossman award at the Coolidge Memorial Luncheon, a short while after his lecture.) A long-term follow-up study was presented of 798 treated roots, some going back as far as 40 years. Dr. Nygaard-Ostby reemphasized his belief that a vital pulp and a necrotic pulp are two entirely different entities demanding different treatment methods. The former requires partial pulpectomy, and the latter needs debridement and filling of the canal in its entirety. A surprising revelation in his results 'was that necrotic cases did better than total pulpectomy ones. The explanation may be that one is

more "daring" in debriding a necrotic case, and there is less fear of pushing root filling material through the foramen. His tables showed a 98.7% success rate with partial pulpectomy in 394 roots; 87% success rate in 116 roots treated by total pulpectomy; and 92.5% success rate in 288 necrotic pulp cases. In answer to a question after his lecture, he said that his product, Kloroperka N-O, shows no shrinkage due to CHCI 3 evaporation, but he can't vouch for its imitators. Its proper use is to glue the gutta-percha to the walls, not to use it as a filling-out cement.

A m e r i c a n A s s o c i a t i o n of Dental Schools, Endodontic Section - Chairman: A. E. Skidmore, W e s t Virqinia University, M o r q a n t o w n Part I (Held in M i a m i Beach, Fla, durinq the A m e r i c a n A s s o c i a t i o n of Dental S c h o o l s meetinq) 9 Herbert Schilder, Boston University. "Evaluation of the basic principles of clinical endodontics." The healing capacity of periapical tissues are of little concern because all lesions heal if treatment is optimally performed. Proper diagnosis, which must be taught as a codified science instead of the current, confusing hodgepodge, is now the prime concern. There is reduced reliance on drugs and more emphasis on the importance of cleaning and shaping the root canal system. The profession is clearly expressing its preference for gutta-percha as the endodontic filling material of first choice. Old myths are being rejected, but clinical endodontists must guard against future myths (such as the autoimmunologie response), which may militate against adherence to the aforementioned enunciated principles.

9 Jay Friedman, dental director, US Administrators, Beverly Hills, Calif. "Evaluation of the delivery of endodontie services to the public." As part of US Administrators quality assurance program, predetermination of benefits is required for all treatment plans in excess of $100. Thus, if extraction of a tooth is proposed by the dentist, endodontic therapy can be recommended instead, and if the tooth is still present, payment for the extraction can be denied. If the proposed extractions are of key teeth, such as first molars, this can prevent serious collapse of the dental arches. By refusing to pay for extractions where teeth obviously should be saved, referrals can be stimulated. If it turns out that dentists do not do root canal therapy, either directly in their offices or by referral, they are removed from the list of participating practitioners. The other side of the coin is the need to recommend extractions in cases where the patient would clearly be in better health if no attempt were made to save nonstrategic teeth. 9 Marwan Abou-Rass, University of Southern California, Los Angeles. "An evaluation of the quality of dental education." A survey of 35 dental schools was conducted to determine the quality of endodontic teaching at the undergraduate level. The findings indicated that more schools are attempting to standardize their curriculums, with emphasis placed on basic endodontics and not on surgical or advanced endodontic techniques. Sixty-five percent of the schools today do not culture; 90% use guttapercha as a filling material; and there is a trend toward decreasing the role of medicaments. The majority of schools fill 1 mm short of the radiographic apex; all of them are in agreement that paste sealer techniques do not measure up; and none of them

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teach the N2 method. Finally, all seem to have the same attitude that schools should teach more diagnosis and pain and emergency management, as well as more theory of endodontics.

Part 2 (Held at the AAE Meetincj) 9 Kaare Langeland, University of Connecticut, Farmington. "An evaluation of the quality of endodontie research." More care should be put into the methodology of investigations. In endodontic research, from the clinical procedures through the laboratory studies, the observations and the criteria by which to evaluate them must all be correlated. The unfortunate disagreements among investigators evaluating the same materials and methods cast doubt on the validity of conclusions drawn in many research studies. Extreme lack of agreement at the present time on what is acceptable in clinical treatment is a reflection of inadequate and inaccurate research. Conclusions do not clearly distinguish between opinion and observation. 9 Calvin Torneck, University of Toronto. "An evaluation of the biological principles of endodontic practice." Despite a greater search for scientific understanding, voids still exist in some basic areas of practice. This is most visible in the role of microorganisms in causing endodontic disease and the behavior of host tissue in the face of pulp injury. In these areas, bias and empiricism still direct the course of therapy, and it is clear that a scientific lag exists--a discrepancy between what is known and what is actually done clinically. The responsibility rests on both parties----on the clinician for complacency with dated knowledge and techniques and on the scientist for ~less than satisfactory dialogues with those less scientifically oriented. The gap is recognized and is being partially

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bridged by endodontic educators who are modifying their clinical teaching in accordance with this need.

Table Clinics m Chairman: Ben Brown, Raleiqh, NC 9 Guillermo Mora, San Jose, Costa Rica. "Study of tooth length." Sixteen hundred extracted teeth (100 samples of each tooth in the arch) were measured. Maximum, minimum, and average tooth lengths were compiled in tabular form and offered as an aid in endodontics. 9 Oscar Balanos, University of Minnesota, Minneapolis. "A scanning electron microscope examination of the walls of small canals after chemomechanical preparation." The study graphically showed the pulpal debris and dentin filings remaining after usual and flared preparation methods. Electron micrographs showed less debris in the flared preparations, but areas untouched by instrumentation were seen in both methods. 9 Phillippe Delivanis. "In vivo study of polycarboxylate amalgam, and Cavit retrofillings." After a two-day period Cavit had the least leakage, but after eight months it showed the greatest amount. Polycarboxylate had spaces around the margins and leakage after an eightmonth interval. Amalgam showed slight leakage at two days, but at eight months had good marginal adaptation with no leakage. 9 Greg Chadwick and David Lukosik, University of Nort/~ Carolina, Chapel Hill. "Intraoral photography techniques." Many techniques were demonstrated. Basic equipment and accessories were shown, as was proper use of retractors, mirrors, and light. The selection of optimal angulation and exposure time was explained. 9 Thomas Butler and John Olmstead,

University of North Carolina, Chapel Hill. "The effect of intracanal medicaments on the properties of temporary restoration materials." All materials tested (Cavit, ZOE, and zinc phosphate cements) were softened by all the medications tested (Cresatin, Formocresol, and camphorated paramonochlorophenol), although Cavit showed some increased surface hardness after seven days. 9 Donald Kleiser and Keith Mullins, University of Kentucky, Lexington. "Pros and cons of Formocresol." Cases in which Formocresol was used in vital pulp extirpations were compared with ones in which no medicaments were used. 9 David Maddox, Medical College of Georgia, Augusta. "Faulty radiographs." Many times improvements can be effected. Overexposed films can be lightened by Farmer's reducing solution. Brown or green films can be refixed, and underdeveloped films can be intensified by chromium intensifier. 9 William Meyers, VA Hospital, Miami, Fla. "The operation of the SonoExplorer." A projected television tape showed the matching of indicator tone to reference sound. 9 Elliot Goldberg, Gary Ries, and Lorne Chapnick, Tufts University, Boston. "Extra mesiobuccal root canal of maxillary first molars." Percentages of incidence according to various studies were cited. General locations were described, and special means to look for the extra canal were suggested. 9 John Hartness, Rocky Mount, NC. "Tidbits of aid to clinical practice." A pressure injection through a rubber stopper for intrapulpal anesthesia was shown, as was a means for modifying rubber dam clamps by narrowing and sharpening the beaks for re-

JOURNAL OF ENDODONTICS I VOL 2, NO 11, NOVEMBER 1976

tention on problem teeth. Externalization of large osteolytic lesions, using a small polyethylene tube available as a handpiece chuck, was suggested. Use of double film packs, with each film developed for a different time, was proposed as a means of ensuring availability of a radiograph of readable density. 9 Thomas McDonald, E m o r y University, Atlanta. "Fiber optics." This modality was demonstrated as an aid in detecting fractures and locating canal orifices. 9 Alfonso Moreno, Monterrey, Mexico. " A technique for filling root canals with gutta-percha warmed within the canal." The warming of gutta-percha in the canal is done with a file attachment on an ultrasonic unit (Cavitron). After placement with cement, the cone is heated in this way, followed immediately by vertical a n d / o r lateral condensation. 9 Eric Hovland, Medical College of Virginia, Richmond. " A technique for splinting teeth." Mesh-backed orthodontic brackets are bonded directly to enamel after acid etching. A labial arch wire shaped outside the mouth is used to connect the brackets. 9 Daniel Garcia, Conrad Jungman, and Thomas Sullivan, Warwick, RI. "Radionuclide imaging as applied to evaluating endodontic procedures." Although used now only as an experimental model in dogs, Tc99 pyrophosphate followed by a scan is a possible means of diagnosing problem lesions such as osteomyelitis. 9 Jack Levi, Austin Johnson, Douglas Mann, Frederick L e r n e r, Fredric Lubit, and Andrew Gershon, Teaneck, NJ. "An experimental model for implanting materials into laboratory animals and making comparisons histologically." Teflon caps containing ZOE were

placed in inferior alveolar sockets of guinea pigs and compared to controls for effective closure of wounds, cellular reaction of the capsule, and appearance of reactive bone surrounding the implants. 9 Manuel Weisman, Augusta, Ga. "Duplicating radiographs." A contact printer and photographic timer switch were used to fabricate an effective duplicator for less than $30. K o d a k R P / D X - O m a t radiograph duplicating film is used. 9 Ernesto Levin, Buenos Aires. " A c u puncture for pain relief in endodontics." The 5,000-year history of acupuncture was briefly reviewed with quotations from the French and Chinese literature. A survey of modern acupuncture was given with its current uses and techniques. THIRD D A Y

AFTERNOON

Scientific S e s s i o n 9 Loren Pilling, psychiatrist, director of the Minneapolis Pain Clinic. "Psychological aspects of the dental patient." The psychiatrist and the dentist have two strikes against them all of their professional lives. People never want to see them willingly. Primarily these professionals should ask themselves, "Do we care enough to try to understand that other person?" Remember, there is a human being at the end of that tooth. Perhaps a shingle should he put out that says "I care," to reduce the patient's apprehensions and anxieties. Everything is accentuated when a person is sick, and a state of depression can ensue. It is sometimes difficult not to get angry with the patient, especially if it is an angry patient one is dealing with. However, by keeping cool the patient will relate better to the practitioner. It is good to know the patient a little better, but it is far better to

know oneself, and then less iatrogenic disease will be incurred. Ifr a practitioner feels insecure about himself, it can show and contribute to iatrogenic disease. The practitioner's biggest problem is to recognize that he has problems. Listen to the noise all around; more people talk than listen. A t the conclusion of his discourse, Dr. Pilling stepped down from the platform and went among the audience, announcing, "We should get off our pedestals and relate with each other." FOURTH D A Y N M O R N I N G Audiovisual Presentations C h a i r m a n : J a m e s E. A i n l e y , Orlando, Fla The only remaining features in the scientific program were three films: Endodontic Surgery, Harold Gerstein, Chicago; Endodontic Therapy and Endodontic Implant, Alfred L. Frank, Los Angeles; and A Simplified Technique o / E n d o d o n t i c Therapy in One Visit, Hello de Freitas e Silva, Brazil. Your reporter took longer than ever to prepare this resume. In part, this was because it was such an exciting meeting, outstanding in so many respects--the very high level of the scientific program, the international flavor, the incorporation of simultaneous translation, and the overall sense of good fellowship and good neighborliness. In preparing the report, it was a distinct pleasure to remain in constant postmeeting attendance with cassettes and notes. For providing such a deeply satisfying experience, thanks are extended to Past President Dr. Robert Uchin and Program Chairman Dr. Gerald Cathey for their vision and creative imagination in developing these concepts and for their competence in carrying them out. Heartfelt thanks, too, to the generous, spirited members who helped gather the material needed to prepare this report: Drs. Russell Grandich, Edward Osetek, Charles Cunningham, Dudley Glick, Anthony LeQuire, Arthur De La Ossa, Harold Rappaport, Marcelo Brimmer, and Frank Kasman. Thanks also to Elly, Dottie, Irene, and Carol, who are always great to work with. 363