TOPICAL ANTIBIGriC TREATMENT OF INFECTED DENTAL PULPS OF MONKEYS By G. Richard Baker Submitted to the Faculty o£ the Graduate School in partial fulfillment of the requirements £or the degree o£ Master o£ Science ~n Dentistry, Indiana University, School o£ Dentistry, 1966. ACKNOWLEDGEMENTS My wife Sydney, and children, Sarah and Richard, have been a great source o£ encouragement during this period o£ graduate education. It is to them that I dedicate this thesis. Dr. David Mitchell has contributed immensely to this research and his guidance has been indeed appreciated. I especially wish to thank Dr. Ralph McDonald who has been such a good friend and has provided assistance in so many ways. Thanks to Miss Shirley Shazer and Dr. Milecent Henry for the very fine histologic sections. Mrs. Redford was an exceptional he~p in caring so well for the animals and preparing them £or surgery. Miss Rosmary Rocap, my classmates, and the members o£ the Pedodontic sta££, assisted willingly when called upon. Thanks to the Illustrations Department £or preparation o£ photographic material and to Miss Lei Houchin £or the splendid typing o£ this paper. To the University o£ Indiana I wish to express my gratitude £or the opportunity to have participated in the program o£ graduate education. TABLE OF CONTENTS INTRODUCTION ..•......................•..... 1 REVIEW OF THE LITERATURE ......•.....•.....• 4 STATEMENT OF THE PROBLEM ..................• 24 EXPERIMENTAL PROCEDURE ......... 0 ••••••••••• 25 I PILar STUDY II PRINCIPAL STUDY DATA ........................................ 34 TABLES AND ILLUSTRATIONS .............•.•... 43 DISCUSS I ON .................................. 58 SUMMARY AND CONCLUSIONS .....•.............. 67 REFERENCES . . . . . . . . . . .. . . . . . . . . . . . • . . • . . . . . .. 7 3 CURRICULUM VITAE ABSTRACT List of Tables Table Page I Histologic Results £or Pulps Treated with the Antibiotic Compound .................. 46 II Histologic Results £or Pulps Treated with the Starch Control ....................... 47 List o£ Illustrations Figures Page 1. Photograph, typical pulp exposure ..........•.. 48 2. Photomicrograph, section £rom an exposed pulp left open 24 hours ..........•.....•...... 49 3. Photomicrograph, section £rom a tooth treated with the antibiotic compound (30 days postoperatively) ...............••.••. 50 4.&5. Photomicrographs, sections £rom teeth treated with the starch control (30 days postoperatively) •.......................••.... so & 51 6. Photomicrograph, section £rom a tooth treated with the antibiotic compound (30 days postoperatively) ...................•..... 51 7. Photomicrograph, section £rom a tooth demonstrating epithelial proliferation (30 days postoperatively) ................••... 52 8. Photomicrograph, section £rom a tooth demonstrating a fixation artifact .........•... 52 9.&10. Photomicrographs, sections £rom a tooth demonstrating perforation o£ the pulpal 11. 12 . . 13. floor . ........................................ 53 Photomicrograph, section £rom a tooth treated with the antibiotic compound ( 90 days pos toper a ti vely) ..................... 54 Photomicrograph, section £rom a tooth treated with the antibiotic compound (90 days postoperatively) ...............••.... 54 Photomicrograph, section £rom a tooth treated with the starch control (90 days postoperatively) ..................•...... 55 , 14. Photomicrograph, section from a tooth treated with the starch control (90 days postoperatively) ..•......•...•.........•. 55 15. Photomicrograph, section from a tooth treated with the starch con~rol (90 days postoperatively) ......................... 56 16. Photograph, demonstrating intra- oral lesions (90 days postoperatively) ...•.... 56 17. Photograph, demonstrating intact restorations (90 days postoperatively) ........ 57 18. . Photograph, demonstrating intra- oral lesion (90 days postoperatively) ......... 57 INTRODUCTION -1- Antibiotics have been used alone as pulp capping agents and as components of various pulp capping com­ pounds in an attempt to preserve the vitality of teeth following pulpal exposu~e. In this regard they have been employed both locally and systemically. Success has been evaluated clinically and histologically. To date the results are inconclusive, as reports o£ clinical success are not corroborated by histological evidence. However, in reality, considering the many antibiotics that have long been available to dental research, and the £act that some ·twenty years have elapsed £rom the first antibiotic pulp capping experiment, there is a paucity o£ well controlled, thoroughly documented, investigations. Presently, it is generally accepted that pulp capping pxoceduxes be limited to young, vital, asympto­ matic teeth, accidentally exposed £ox a brief period of time in a relatively aseptic environment. Pre­ operative diagnosis of pulpal status, based on objective and subjective evaluation, is thought to be critical and determines the method o£ treatment. The criteria o£ selection are so oriented that one must choose to treat only those pulps with minimal infection. I£ adhered to, the probabi.li ty o£ extensive or advanced -2- involvement is lessened. However, the pathological status o£ a pulp so evaluated may well be o£ a more severe nature and yet still retain a significant degree of vitality. Regardless o£ the remaining vitality, i£ the tooth fails to meet the rigid criteria for capping, it cannot be considered a candidate £or the procedure, and thus must be treated by more radical methods o£ con­ servation, or be removed. Therein lies the need for a pulp capping agent that can potentiate the innate ability of the vital pulp to effectively control and reverse the more severe infections. This modified double-blind invest·igation was undertaken to examine the hypothesis .that for any given species the utilization o£ an antimicrobial agent, innocuous to healthy tissue yet potent enough to destroy or control the invasive pathogenic oral microorganisms, could allow the natural defense mechanism of a vital pulp to overcome the infection, repair the damage, and survive. In this experiment, two antibiotics in a starch vehicle were placed over surgically exposed and intentionally in- £ected pulps of monkey teeth. In g~neral, it was hoped that the results o£ this experiment would expand existing knowledge of the histologic response of the pulp to topically applied antibiotics, and possibly demonstrate -3- their effectiveness in txeatment of the exposed vital pulp. Moxe specifically, it was hoped that this particular compound would pxove to be compatible with vital tissue and yet facilitate resolution of pulpal infection. REVIEW OF THE LITERATURE -4- Antibiotics were prescribed £or dental problems soon after their first clinical application in medicine. In 1942 penicillin therapy, as an entity, first appeared 1 in the Quarterly Cumulative Index Medicus. At approxi- 2 mately the same time the Index to Dental Literature listed several dental publications which made reference to the dxug. Great expectations were envisioned £or its use in dentistry. It was only a matter of time until penicillin was used as a pulp capping agent. Since then, many different antibiotics, in numexous combinations, have been used for this purpose. For purposes of organization and clarity this section will be broken down into sub-sections, each considered separately as it pextains to the treatment of pulp exposures with antibiotics. They are as follows: (1) use of antibiotics alone, (2) use of antibiotics combined with miscellaneous medicaments, and (3) use o£ antibiotics combined with corticostexoids. The Use of Antibiotics Alone 3 In 1947, Bonner reported that out of 162 carious pulp exposures, only eight pulpal deaths resulted following the placement of a capping agent consisting of dry crystal- line penicillin mixed with glycerine. It was felt that the pulp was a durable organ, and if infection was present, -5- it could be treated in the same manner as any other body tissue. Pre-operative and post-operative evaluations l were not very thorough nor well documented; however the results were very encouraging. 4 In 1950, Kutscher reported the use of a penicillin capping agent on cariously exposed pulps. Clinical evaluation o£ 54 teeth six weeks post-operatively showed a 98 percent success rate. The author felt that penicillin, in e££ective concentrations, would be bacteriocidal against the bacteria most common in dental caries, diseased pulp chambers, and infected root canals. It was thought that this procedure demonstrated a definite advance in pulp therapy as most operators were reluctant to cap a nclean" surgically exposed pulp, let alone one resulting £rom the invasion of caries. 5 Webb, reporting in 1950, recommended the intra- muscular injection of 300,000 units o£ procaine penicillin for the treatment o£ painful pulpitis and hyperemia. He believed one injection usually was sufficient; two were sometimes needed. No other adjunctive or supportive proce~ures were used. Sample size, controls, and methods of evaluation were not given. The article predominantly was conjectural in nature, but is significant in that it -6- emphasiz€d a systemic mode of treating painful pulpitis. 6 In 1951, Gilberg, reported that when ·a pulp capp~ng paste, consisting of penicillin and distilled water was placed over 205 pulpal exposures, 200 were considered clinically successful after a 36 month period of observation. The age range of the patients was from two to 50 years and age was not considered a significant factor in success or failure. 7 Rosen, ~n 1952, reported a 90 percent success rate using a penicillin pulp capping agent on deciduous teeth. 8 Amler further attempted to control pulpitis by systemic antibiotic therapy using pen~cillin and terramycin in 1954. He achieved 68 percent success in the treatment of 22 teeth which were candidates for root canal therapy or extraction and which had a history of pain. No adjunctive treatment was used. 9 James et al in 1957, investigated the histologic response of amputated pulps to calcium compounds and anti- biotics. The teeth selected for the study had vital pulp exposures, presented a history of pain, and were ordered for extraction. The teeth were sedated for from one to seven days prior to the pulpotomy procedure. The total sample consisted of 113 teeth. Various calcium compounds -7- and antibiotics were used. From the data collected there . appeared to be a direct relationship between the severity of inflammation and the incidence of internal resorption; and an inverse relationship between the degree of inflammation and the incidence of bridging. Since most of the antibiotic pulp studies conducted by this time had been with penicillin, it is interesting to note the responses in this study. 0£ nine teeth treated with penicillin, 11 percent showed calcific bridge formation ox organization, 56 percent demonstrated internal xesorptiun, and 89 percent showed moderate to severe inflammation. The other antibiotic preparations .which were used were Gxossman 1 s polyantibiotic (penicillin, bacitracin, sodium caprylate), oxytetracycline* and chlortetracycline.+ The pulpal response to these was quite similar to that of penicillin. When an antibiotic was combined with a calcium compound, the pulpal response resembled that occurring as a result of the antibiotic alone rather than being due to the calcium. * + Terramycin, Pfizer Laboratories," New York, New York Aureomycin, Ledexle Laboratories (A Division of American Cyanamide Co.) Pearl River, New Yo:rk -8- It is of interest to note the findings of Kutscher 10 and Yigdall who stated that the antibacterial activity . of penicillin is nearly completely destroyed when incorporated with calcium hydroxide. Their report showed that Aureomycin, streptomycin, and Terramycin retained some antibacterial activity when incorporated with calcium hydroxide. 11 Ramnarine, reporting in 1956, included 75 teeth with carious exposures, 150 large cavities, and 20 pulpo- tomies, in a study that described the use o£ Terramycin on infected pulps in childxen. The author reported three failures out of 245 teeth treated. His method specified that the antibiotic be left in place for only two to £our minutes prior to placing the filling. The post-operative evaluation was made after three months and roentgenograms were made when deemed necessary. 12 In 1958~ Seltzer and Bender observed that pulpal necrosis and the development o£ an apical granuloma occurred in every instance when an aqueous solution o£ 250,000 units o£ penicillin was used on vital pulp tissue of dogs. The medicament was applied to the pulp tissue, in solution, £or a very short period. Following this application, asbestos fibers were used to cover the -9- exposure site and a covering of amalgam was placed. The sample consisted of 58 teeth from three dogs, observed for periods of seven, 30, and 90 days. 13 Maeth, in a 1959 study, observed successful resolution of pulpally involved teeth with deep carious lesions, com- plicated by rar·efying osteitis, when treated with oxytetra- cycline applied topically. In addition, if the condition was acute, with a history of pain, oxytetracycline was administered systemically for 24 hours. Sample size was not given and many details were lacking. 14 Burke and Holmes investigated, in 1961, the effect of local antibacterial agents on bacteria in the dental pulps of rats. Bacteremias were induced by the intravenous injection of known quantities of Staphylococcus aureus. Various antibacterial agents were placed over the exposed pulps of 196 teeth. These agents were combined with zinc oxide and eugenol. Cultures were taken on one group of rats one day after injection, and on the other group at a seven day post-injection interval. Penicillin and Bacitracin* were the antibiotics used; they showed 47.5 percent and 50.9 percent positive cultures respectively. The same two drugs, on a smaller sample of rats, demon- * Bacitricin, Lilly and Company, Eli; Indianapolis, Indiana -10- strated 6.9 percent and Q.O p~xcent positive cultures aftex the seven day interval. The Use of Antibiotics Combined with Miscellaneous Medicaments 15 Bur~an, in 1951, achieved a 75 percent success xate when a compound containing penicillin and camphorated para- chlorophenol was used. The sample consisted of teeth so badly damaged that endodontics or extraction usually would have been the treatment. There was a history of pain in most cases and early periapical changes were seen on the radiographs o£ some. In this experiment · caxe was taken not to expose the pulp, and the deeper layexs o£ decayed dentin were not removed. In essence, the treatment amounted to an indirect pulp capping procedure. 16 Roth, in 1952, recommended that Aureomycin be mixed with zinc oxide - eugenol, copper cement, or zinc phos- phate cement to be used as a pulp capping compound fox deciduous teeth. Statistics were not given in this report and the observations were empirical. The author stated that by using the compound there resulted prolonged re- tention of the deciduous membex until shed. Reference was not made as to whether resolution o£ the pathosis 17 took place. Lepine et al had previously obsexved that aureomycin interfered with pulp healing by retarding -11- proliferation of the fibroblasts and epithelial cells. 18 In 1953 1 Roberts reported on the adjunctive use of intramuscular penicillin injections in the treatment of exposed vital pulps. Calcium hydroxide was used locally. After 60 days 94 percent were evaluated clinically as being successful. After three years 23 o£ the original 44 treated pulps were re-evaluated. Of this number, 21 were still vital. 19 Seelig et al, in 1954 stated the results of an in- vestigation whereby surgically exposed pulps of a Rhesus monkey were capped with penicillin G potassium plus cal- cium carbonate. This was the first histological evaluation of an antibiotic pulp study. The pulps of 20 teeth were exposed and the pulp tissue macerated by the bur. The experimental penicillin capping compound was then placed over the exposure site in 11 teeth. 0£ the remaining teeth a mixture of zinc oxide - eugenol was placed on four, zinc phosphate cement on one, two were left open, and nothing was done on the other two. There was a time lapse of seven days from the time of operation to that of sacrifice and fixation. It was observed at the time of extraction that seven of the 11 zinc phosphate cement coverings, over the antibiotic paste, were missing and one -12- was loose. When the zinc oxide - eugenol contacted the pulp an inflammatory response occurred with subsequent abscess formation. Similar results occurred when the zinc phosphate cement was placed in direct contact with the pulp. A normal pulp was observed under all appli- cations of the penicillin capping compound. Unfortunately the sample size was small and the loss of so many pro- tective coverings, over the experimental drug, further mitigated the conclusions. 20 Via, reporting in 1955, described a histologic study of four monkey teeth. Pulpotomies were performed and the following materials placed; (1) Grossman's po~y- antibiotic (penicillin-bacitracin-streptomycin-sodium caprylate in a vehicle of silicone fluid) plus barium sulphate, (2) Calcium hydroxide, (3) Barium sulphate and, (4) A control of zinc oxide - eugenol. Success was achieved in 1, 2, and 3. The sample was very small and the antibiotics were not tested apart from the other ingredients. 21 Englander et al conducted, in 1956, a clinical evaluation of pulpotomies in young adults. The sample con- sisted of 228 teeth of which the majority had been associated with a history of pain and had been ordered £or -13- extraction. Grossman's PBSC paste, tetracyclines (Au~eo- mycin and Terramycin), penicillin powde~, ·and *Chloram- phenicol, we~e some of the antibiotics used on 61 teeth4 The tetracyclines in calcium salts (unspecified), and Grossman's PBSC demonst~ated 100 percent clinical success. Tetracycline in non-calcium dilutants showed 82 pe~cent success; penicillin powder (undiluted) _36 percent success; and chloramphenicol was not successful at all. The findings seemed to indicate that antibiotics in combination with one another, or with calcium compounds, enhanced thei~ thera- peutic value in pulpotomy. 22 Feitelson, in 1956, tested a pulp capping paste which combined calcium hydroxide and approximately 10,000 units of crystalline penicillin G. Out of 83 permanent and deci- duous teeth with carious pulp exposures, followed for a minimum o£ one yea~, only seven £ailu~es ~esulted. Acute periapical abscess o~ pe~iapical bone change constituted failure. The rate of success was 91 pe~cent in the prima~y teeth and 92 percent in the pe~manent teeth. 23 In 1957, Gollobin reported the use of a compound con- taining Te~ramycin and zinc oxide - · eugenol, on an un- specified numbe~ o£ teeth with near or actual pulpal * Chloramphenicol, Parke; Davis, and Company, Detroit, Mic~igan . -14- exposure, and on pulpotomized teeth. Statistics were not given concerning sample size, controls, or degree o£ success. Operated teeth were followed £o:r one year and the author observed few failures. 24 Sanders, in 1959, described the use of a paste con- taining *Ach:romycin, camphor a ted pa:rachlo:rophenol, .and calcium hydroxide suspended in a solution of methyl cellulose. The sample consisted of extensively carious teeth with some having pulp exposures. Of 38 teeth treated, 34 were considered successful. Success was achieved if all adverse clinical symptoms had disappeared upon :re-examination of the patient at a later date, the time of which was unspecified. ,.. 25 In 1960 Shay et al used a pulp capping paste con- taining ach:romycin, pa:rachlo:rophenol, and calcium hydroxide. They achieved a 97 percent success rate when this paste was applied to pulp exposures. 26 Gardner et al reported, in 1962, on experimentally induced pulp exposures on the teeth of dogs made by high + speed instruments. The basic dxug evaluated was Neosporin. * Achromycin; Lede:rle Laboratories (A Division of American Cyanamide Co.) Pearl River, New York + Neospo:rin, Burroughs, Wellcome & Co. (USA) Inc., Tuckahoe, New York · -15- The drug is a combination of polymixin B, bacitracin, and *Neomycin. Para-monochlorophenol was used with Neosporin on one part of a sample of 27 teeth. The other portion was capped with the above mentioned drugs in addition to calcium hydroxide. When the 27 teeth were histologically evaluated 26 showed degenerative changes, including acute pulpitis in 24 of the teeth, an abscess in one, and hyaline necrosis in another. The Use of Antibiotics Combined with Corticosteroids 27 Sidky in 1957 described the use of a medicament for use in pulpotomyj it consisted of hydrocortisone, o· , ~cillan, and calcium hydroxide. Prerequisites for its use were asymptomatic teeth in young healthy patients. He considered the medication to be very effective. 28 Kiryati reported, in 1958, that a combination of drugs was more effective than one drug used alone. The sample consisted of 192 maxillary first molars in 96 albino rats. Different combinations o£ medicaments were placed and the results evaluated histologically. Hydro- cortisone was in all combinations except one, that being a mixture of oxytetracycline and chloramphenicol with calcium carbonate, or zinc oxide - eugenol. The animals * Neomycin, Lilly and Company, Eli; Indianapolis, Indiana ~16- wexe sacrificed at two, £our, and £xom eight to 12 week intexvals. Serial sections were then made. The most effective combination, when evaluated £rom eight to 12 weeks, was hydrocortisone, oxytetracycline and chloram­ phenicol, which produced complete healing in 52 percent of the teeth, incomplete healing in 38 percent, with necrosis occurring in 12 percent. Hydrocortisone, Neo­ mycin, and bacitracin produced 20 pexcent complete healing, 20 pexcent incomplete healing, and 20 percent necrosis, over the same period o£ time. The antibiotic mixture without hydrocortisone, but still with calcium hydroxide or zinc oxide - eugenol, showed 40 percent complete healing, 30 percent incomplete, and necrosis occurred in 30 percent. In this study, incomplete healing is described as calcific bridging still in the primaxy stages o£ £ormation, showing irregular fibrous calcification without regulax dentin being formed, but .with the final result o£ healing. It was mentioned that the pulps were exposed and left open £rom one to 48 hours. Reference is made to this throughout the article, but thorough documentation and any correlations with regard to the extent of infection and the time left exposed is lacking. It is interesting to note the similarity o£ proceduxe in this experiment and that o£ -17- 29 Kakeashi et al who made pulpal exposures on the molar teeth o£ germ-free and conventional rats. 30 Kiryati observed the effects of streptokinase in combination with oxytetracycline and cortisone in 1962. Pulpal exposures were made in the molar teeth of white rats and treated with various combinations of the afore- mentioned drugs. Streptokinase did not seem to affect the healing potential of the drug. There was a similar pulpal response under all the medications; however, the combination containing streptokinase, oxytetracycline, and cortisone was found to be more successful. 31 In 1962 Schroeder and Triadan reported on the in- corporation of a synthetic corticoid, triamcinolone, into an ointment containing Chloramphenicol and a four percent xylocaine solution. This ointment was used on vital teeth that presented a history of sevexe pulpitic toothache. A total of 214 teeth, mostly postexioxs, were treated. The average patient age was 28.5 years. Pain disappeaxed in most instances two to three hours following the initial application. At the end of two to three weeks pain was not in evidence and all teeth showed normal vitality. The histologic picture of two teeth, one healthy, the othex diseased, was briefly described. A diseased canine of a -18- 17 year old patient with a history of clinically severe pulpitis, demonstrated slight hyperemia w{th no signs of acute inflammation. 32 In 1962, Fiore-Dpnno and Baume experimented with the application of various compounds, each containing a cor- ticosteroid and an antibiotic, on pulpotomized teeth with a history of painful pulpitis. Although clinical symptoms disappeared, giving every indication of successful resolution of the ir~lammatory status of the pulp, histological corroboration of success was lacking. Serious disadvantages to the use of these corticoid-antibiotic compounds included the absence of a solid barrier. An op€n pulp may become increasingly susceptible to reinfection as the hermeticity of the filling material decreases with age. Also meta- plastic fibrosis of the pulp, arrested dentin formation, and residual or induced chronic inflammation were observed. 33 In 1964, Olsen reported on the use of a cortico- antibiotic preparation on 370 cases o£ hyperemia, pulpitis, and apical periodontitis. After six to 12 months of clinical observation only one percent of the teeth treated were considered failures. 34 Mager reported, in 1964, on the treatment of pulpitis with synthetic steroids combined with antibiotics. This -19- experiment constituted a clinical pilot study. The ex- perimental compound used was Ledermix - R. 0£ the 20 teeth treated, 19 remained vital at the end o£ six months. 35 In 1964, Ehrman described the use o£ Ledermix "An and nBn on a variety o£ pulpal conditions ranging £rom hyperemia to acute supurative pulpitis. It was significant that 16 o£ 22 teeth, in the supurative pulpitis category tested non-vital six months following treatment even though the initial pain had subsided. Success with the compound was higher in the treatment o£ hyperemia than in the more severe forms o£ pulpal pathology. 36 Lawson and Mitchell, combined erythromycin and streptomycin with a potent steroid, *flurandrenolone, to treat 52 teeth giving a history o£ painful pulpitis. A double-blind procedure was used in which the pulps were capped with the experimental compound in 25 teeth and with a starch control in 27 teeth. The results were evaluated up to 164 days. There were no failures among the teeth treated with the experimental drug and the teeth treated with the control showed 52 percent success. An attempt was made to correlate the clinical and histological condition o£ seven teeth. Histopathologically, * Cordran R Lilly and Company, Eli; Indianapolis, Indiana -20- the pulps capped with the experimental compound showed a decided advantage over those treated with the control. In the former, tissue reactions were less severe and new hard tissue formation was more evident in an attempt to close off the exposure site. Clinically, painful pulpitis appeared to be rever- sible. The limited histological evaluation tended to support this. However, it was mentioned that what appeared to be clinical success at the present, may prove to be future failures .. 37 Baume listed indications for treatment o£ various pulpal conditions in 1965. He recommended that pulp capping be used only when the cavity is in close proximity to the pulp or when there has been an accidental exposure. Further, the tooth must be asymptomatic. Caution is made against the use o£ mixtures of cortisone, antibiotics, and calcium hydroxide, which seem to produce clinical success but when evaluated histologically, show a de- generative condition. It was stated that, without exception, there occurred fibrous metaplasia of pulpal tissue, irreversible inhibition of dentinogenesis, and chronic inflammation. All of the preceding occur without clinical symptoms and may result in the pulp dying after what -21- had appea~ed to be successful healing. 38 Mullaney et al continued, in 1966, with a study 38 initiated by Lawson and Mitchell in which a po~tion of the o~iginal sample was ~ecalled fo~ fu~the~ clinical evaluation. Of 21 teeth that ~eceived treatment, 15 were still conside~ed to be successful. This xepxesented a significant d~op £~om the 100 percent success reported in the preliminary investigation. A stringent double- blind testing procedure was used in this po~tion of the investigation and also in the histologic po~tion of the study. In the second part o£ this investigation the experi- mental co~ticoid-antibiotic compound (erythromycin, st~eptomycin, flurandrenolone) and the starch control we~e applied to the mechanically exposed pulps o£ monkey teeth. A modified double-blind p~ocedure was used in which one-half of the sample o£ 28 teeth were treated with the experimental compound and the othe~ one-hal£ treated with the control. Twelve teeth were removed and histologically evaluated after 90 days and the ~emaindex afte~ 180 days. Rega~dless of when the teeth were re- moved, £or both the expe~imental drug and the control, the majo~ po~tion o£ the pulp tissue in all teeth was -22- no~mal, with the exception of two sta~ch cont~ols which showed abscess formation and ma~ked inflammation. The corticoid-antibiotic treated teeth showed a significantly large~ deposition of dentinoid "b~idging" mate~ial unde~ the exposure site when compa~ed to teeth t~eated with / the sta~ch cont~ols. The clinical portion of the investigation indicated that painful pulpitis was a reve~sible pxocess and that the co~ticoid-antibiotic mixtu~e is of the~apeutic value. The animal study indicated that the~e was some advantage to using the expe~imental d~ug, although there was not an appreciable difference from those pulps which we~e treated with the starch controls. 39 Schneidex and Lawson conducted a dou~le-blind pulp capping study which attempted to evaluate on a comparative 36,38 basis a corticoid-antibiotic mixture and a calcium hydroxide powder £or. treating exposed pulps in primary teeth. Clinical success was recorded: 76 percent in 29 teeth treated with the corticoid-antibiotic mixture and 90 percent in 29 teeth treated with calcium hyd~oxide. Calci~m hydroxide proved to be more effective in the treat- ment of carious exposures. An attempt was made to do all capping procedures under conditions approximating asepsis. -23- Eleven of 14 teeth removed for histopathologic study were pre-planned surgical exposures. Histologically, none were considered to be completely successful although all were considered clinically successful. l.- STATEMENT OF THE PROBLEM -24- Pathog n ic microorganisms are considered to play a prominent role in the initiation o£ pulpal pathology when the vital dental pulp is exposed. There is evidence to indicate that the presence o£ bacteria is the most significant £actor in prohibiting healing. The review o£ literature describes many experiments whereby antibiotics have been used to cap exposed pulps. It is felt that additional investigation into this area is warranted since the results have tended to be conflicting and inconclusive. This double-blind investigation was undertaken to examine the hypothesis that £or any given species, the utilization o£ an antimicrobial agent, innocuous to healthy tissue, yet potent enough to destroy or control the invasive pathogenic organisms, would allow the natural defense mechanism o£ a vital pulp to overcome the infection, repair the damage, and survive. This experiment should expand existing knowledge of the pulp 1 s response to topically applied antibiotics, and reveal the effectiveness of such treatment £or the exposed, contaminated, vital pulp. · EXPERIMENTAL PROCEDURE -25- PILOT STUDY Preparation o£ the Animal £or Surgery One Macaca mulatta monkey was used £or the study. The animal was removed £rom its cage and anesthetized with the help o£ laboratory assistants. Nembutal sodium was injected intraperitoneally by means o£ a 20 gague short needle. The recommended dosage was used; 1.00 ml (10 mg) o£ nembutal sodium for every three pounds o£ body weight. It was necessary in several instances to give an additional ~ ml to obtain a more profound leyel o£ anesthesia. The animal was then placed on the operating table in a supine position with the head tilted back to pro­ vide an unobstructed airway~ To facilitate movement o£ the tongue for ease of operation and visibility, it proved advantageous to clamp the tip o£ the tongue with a large hemostat. This also aided in keeping a clear airway by preventing ingress o£ the tongue. Surgical Procedure The pulps o£ the permanent maxillary and mandibular central incisors were surgically exposed. Bacterial con­ tamination was desirable and therefore a rubber dam or other aseptic measures were not employed. -26- A class V cavity preparation was made on each permanent tooth. High speed rotary instrumentation, using a No. 57 or No. 58 friction grip bur rotating at maximum speed, under approximately 30 pounds of pressure, was used to cut the preparation to a depth closely appxoximating the pulp. A water spray was not used in the cutting procedure. An assistant intermittently administered short blasts of air to clear the area of debris. A careful attempt was then made, with a slowly revolving latch type No. 4 round bur, to remove additional dentin to a point just short of entering the pulp. It had been intended that the exposure be made with a hand instrument to minimize the number of dentin chips introduced during surgical ' exposure. An explorer point was used to expose the pulps of the two maxillary incisors and the No. 4 round bur penetrated the pulps of the two mandibular incisors~ The actual exposures were fairly large in each instance and bleeding was induced with the No. 4 bur or the explorer point. The exposed pulps were left open to the oral environ­ ment for approximately 24 hours. At the end o£ 24 hours, the teeth were extracted and placed in a 10 percent formalin solution. -27- Conventional surgical procedures were used to extract the teeth. Removal of the labial plate of bone with an automatic bone impactor (Dudley) facilitated the extractions. Pedodontic forceps No. 101 proved to be of considerable value as they were readily adaptable to the anatomical form of the teeth. Laboratory Procedure The teeth were then removed £rom the 10 percent formalin solution and ground down on the mesial or distal surface of the tooth with a rotating stone wheel under a water spray until the pulpal outline could be seen. The teeth were then placed back in the 10 percent formalin £or complete fixation. Decalcification and the remainder o£ the work was performed by a laboratory technician. Serial paraffin sections seven microns thick were made through the exposure site. Alternate sections were then stained with a Brown and Brenn stain which is a differential staining method for demonstrating bacteria in tissue sections. Selected alternate sections o£ each tooth also were stained with hematoxylin and eosin in the con­ ventional manner. -28- PRINCIPAL STUDY Formulation of Medicaments The drugs used in this study were manufactured by Eli Lilly and Company. The composition of the experi­ mental compound was as follows: Erythromycin estolate (Ilosone R) Streptomycin sulfate Starch 10% 10% q. s. The control capping material was composed of pure starch. The materials to be tested, coded and labeled com­ pound ~ and ~' were dispensed in small brown bottles to the investigator who was. not aware of the identity of the contents. The study was then carried out using one principle of a double-blind testing procedure~ The investigator, not aware which medicament he was using, could not be biased in favor of either material. The physical properties of the two materials were very similar and could not be visually differentiated unless labeled. The bottle labeled compound ~ contained the starch control and the bottle labeled compound B contained the antibiotic compound. -29- Preparation of the Animals for Surgery Two Macaca speciosa and one Macaca mulatta monkeys were used for the study. Each animal was removed from its cage and anesthetized with the help of laboratory assistants. Nembutal sodium was injected intraperitoneally by means of a 20 gag~e short needle. The recommended dosage was used; 1.00 ml (60 mg) of Nembutal sodium for every three pounds of body weight. It was necessary in several instances to give an additional ~ ml to obtain a more profound level of anesthesia. The animal was then placed on the operating table in a supine position with the head tilted back to pro­ vide an unobstructed airway. At this time full mouth radiographs were made. To facilitate movement of the tongue for ease of operation and visibility, it proved advantageous to clamp the tip of the tongue with a large hemostat. This also aided in keeping a clear airway by preventing ingress of the tongue. Surgical and Therapeutic Procedures The pulps of 57 anterior and posterior permanent teeth and nine posterior deciduous teeth were surgically exposed. Bacterial contamination was desirable and there- fore a rubber dam or other asceptic measures were not employed. -30- · A class V cavity preparation was made on each per­ manent tooth and an occlusal preparation made for each deciduous tooth. High speed rotary instrumentation, using a No. 57 or No~ 58 friction grip bur rotating at maximum speed under approximately 30 pounds of pressure, was used to cut the preparation to a depth closely approximating the pulp. A water spray was not used in the cutting procedure. An assistant intermittently ad­ ministered short blasts of air to clear the area of debris. The method o£ exposing the pulp for the permanent anterior teeth was essentially the same as that used in the pilot study. However the pulps of the permanent posterior teeth and the deciduous teeth were routinely exposed with a high speed friction grip No. 57 or No. 58 bur rotating at maximum speed under approximately 30 pounds o£ pressure. After each exposure the pulp was further macerated by an explorer point or by the bur itself. The actual exposures were fairly large in each instance (Figure 1). Each exposed pulp was left open to the oral environ­ ment £or at least 24 hours and no longer than 26 hours. The animal was then anesthetized in essentially the same manner as the day before. Impacted food debris was . -31- removed by means o£ a small spoon excavator and short blasts o£ air. The cavity preparation was wiped clear with a cotton pledget moistened with saline solution. Just prior to insertion of the capping material saliva from the tongue and vestibular areas was carried into the pulp on the tip of an explorer point in a further attempt at contamination. This also served to disrupt the blood clot. The preparations were then dried with air and one of the experimental pulp capping agents was placed into and over the exposed pulp. The capping agents were mixed with ordinary tap water to a slightly moist, but firm, consistency. An amalgam carrier was used to carry the capping agent to place and a TP 3 plastic instrument (Tarno) was used to firmly tamp the material to position. In the process a small amount of the material was purposely forced into the pulp and a moderate amount was spread out over the floor of the preparation. Upon setting the excess material was then trimmed from the walls of the preparation with a No. 557 bur rotating at a very low speed. This was followed by the insertion of a thick mix of zinc oxide - eugenol into which crystals of zinc acetate had been incorporated to -32- accelerate setting. The surface of the restoration was then smoothed to conform to the outline of the tooth. Twenty-nine permanent teeth and nine deciduous teeth were extr~cted 30 days following treatment. Twenty-eight permanent teeth were extracted 90 days following treatment. Conventional surgical procedures were used to extract the teeth. Removal of the labial and buccal plates o£ bone with an automatic bone impactor (Dudley) or surgical bur greatly facilitated the extractions. Pedodontic forcep No. 101 proved to be o£ considerable value as the beaks were readily adaptable to the anatomical form of the teeth. Immediately upon extracting a tooth it was placed in a 10 percent formalin solution for initial fixation. Alternate placement of the unknown capping materials was used in order to obtain a better distribution of teeth treated with the antibiotic compound and the starch control. The animals were placed on a soft diet until sacri ­ ficed in order to minimize abrasion of the restorations. Clinical Observations A brief oral examination was made 15 days po~toperatively to check primarily on the intactness of the zinc oxide - eugenol restorations. At the time each animal was sacrificed a very complete -33- oral examination was given. Soft tissues were observed fox evidence of clinical pathology, restorations checked fox intactness, and each tooth tested for mobility. In addition, the weight of each animal was recorded and com­ pared to the pre-operative weight. Full mouth radiographs were also taken at this time. Laboratory Procedures The teeth were then removed from the fixing solution and ground down with a rotating stone wheel under a water spray until the pulpal outline could be seen. The teeth were then placed back in the 10 percent formalin fox com­ plete fixation. Decalcification and the remainder of the work was performed by a laboratory technician. Serial paraffin sections seven microns thick were made through the exposure site. Alternate sections were then stained with hematoxylin and eosin in the conventional manner. Selected alternate sections of each tooth were stained with Brown and Bxenn stain which is a differential staining method fox demonstrating bacteria in tissue sections. DATA -34- The pilot po~tion of the investigation was designed to ascertain if the surgically exposed pulps of a Macaca ' mulatta monkey we~e actually infected by being left open to the oral environment £or a period of approximately 24 hours. Histologic serial sections were made of two maxillary and two mandibular central inciso~s. Microorganisms were 40 demonstrated by using a Brown ·and Brenn staining technique. The microorganisms were observed in scattered clusters in the immediate area of the exposure and appeared to be gram- positive cocci (Figure 2). The gram-positive cocci. were the only bacteria which could be identified with reasonable 41 accuracy when this staining technique was used. Stanley has made the observation that in their studies, using the Brown and Brenn staining technique, they do not look for gram-negative organisms because dead gram-positive bacteria will frequently appear gram-negative. In the principal portion of this investigation 57 per- manent teeth and nine deciduous teeth we~e extracted for microscopic study. The pulps had been surgically exposed, left open to the oral environment £or approximately 24 hours, and then capped with either the antibiotic or con- trol medicaments. Histological evaluation of each specimen -35- may be seen in Tables I and II. CLINICAL OBSERVATIONS O~al Examination 15 Days Following T~eatment. The animals we~e fo~cibly ~est~ained and only a supexficial examination was given at this time. The~e we~e no detectable des­ c~epancies and all of the ~esto~ations appea~ed to be in­ tact. Oxal and Radiog~aphic Examination 30 Days Following Txeatment. All of the animals ~egiste~ed weight gains and appeaxed to be in good health. An oral examination was given each while unde~ gene~al anesthesia. The class V restoxations in the permanent teeth were in place and appeared to be intact. Six o£ the occlusal restorations in the deciduous teeth had been lost and three appeare·d to be loose. A small mass of fib~ous tissue was observed in thxee of the cavity preparations from which the xestorations had been lost. Excessive mo~ility was negative for all of the pex­ manent teeth and positive for six of nine deciduous teeth. Dxaining palatal fistulas wexe obsexved in the axea of the permanent maxillary xight second molar and the permqnent maxillary left second premolar, designated No. 16 and 20 in Table II. An area of vestibulax swelling and d~ainage was seen opposite the lower left first premolar, -36- designated No. 22 in Table II. Intra oral radiographs revealed xadiolucent areas around the roots of these teeth. Oral and Radiographic Examination 90 Days Following Treatment. Only one animal remained at this examination. Once again a weight gain was registered and the clinical picture was relatively unchanged at this time. The intra oral lesions observed at · the 30 day examination continued to· be evident and presented a quite similar appearance both clinically and radiographically (Figures 16 and 17). It is very significant that the zinc oxide - eugenol restorations were in place and apparently intact in each of the teeth treated with antibiotic capping material ot starch control capping material (Figure 18). Although not pertinent to this investigation, it was observed that marked deposits of calculus accumulated in the 90 day post-operative period (Figures 1, 17 and 18). HISTOLOGIC EVALUATIONS Histologic Evaluation of Permanent Teeth 30 Days Following Treatment. An inflammatory response of varying degree was seen at the exposure site in each of 26 pulps evaluated 30 days following treatment. Inflammation was considered to be relatively mild or moderate in all of the antibiotic -37- treated pulps and was limited to the immediate vicinity of the exposure in six specimens of this group. The remainder showed inflammatory cells extending beyond the exposure but still limited to the coronal portion of the pulp. The inflammatory cells were few in number and were mostly lymphocytes and plasma cells. By far, the greater portion of the pulp was intact, free of inflammation, ·and considered to be normal (Figure 3). Pulps treated with the starch control capping material exhibited a much wider range of inflammation. In the majority of the control teeth, there was a picture o£ severe inflammation extending into the. deeper confines of the pulp (Figure 4). Complete necrosis was evident in several pulps (Figure 5) and microorganisms could often be observed when the pulp was necrotic. Five pulps treated with the control capping material presented a response quite similar to those treated with the antibiotic, in that they showed a mild to moderate inflammatory picture with moderate to large depositions of reparative dentin. How­ ever, one o£ the five pulps exhibited a small amount of reparative dentin. As a group, the pulps treated with the antibiotic com­ pound demonstrated a decidedly milder and more favorable -38- inflammatory response than did those pulps treated with the starch control. Some vaso-dilatation was observed in all of the pulps when vital tissue was present. Reparative dentin was deposited on the walls and around dentin chips which had been introduced in exposing the pulp, in large amounts in all pulps treated with the antibiotic medication. The dentin formed according to the pattern of the disturbed odontoblastic processes cut during , cavity preparation in the vicinity of the exposure and appeared to form on the opposite wall only when dentin chips were located in close proximity. Reparative dentin around a chip often coalesced with that around other chips and with depositions on the walls to create an .attempt at bridging. Complete bridging was not seen in any pulp but the extent of this phenomena appeared to be proportional to the alignment and number o£ chips and the amount of reparative dentin deposited around them (Figure 6). Pulps treated with the control medication did not show consistent deposition of dentin on the walls nor around the dentin chips. The majority exhibited small to negligible amounts. Three pulps in this group demonstrated deposition in abundance with a good bridging attempt. In most instances a negligible amount of reparative dentin was seen when -39- the pulp was severely inflamed or necrotic. A thin band o£ ~pithelial tissue had proliferated over the exposure site in one o£ the antibiotic treated pulps (Figure 7). Beneath this were many chronic in­ flammatory cells which were limited to the coronal portion o£ the pulp and diminished in number as they extended apically. Reparative dentin was present in large amounts but the arrangement o£ the chips was not conducive £or coalescence o£ the new dentin. A maxillary left lateral incisor presented an unusual appearance which was the result o£ having been allowed to remain out o£ the fixative solution £or approximately 12 hours (Figure 8) before being found. After having been initially fixed for approximately two hours the tooth was lost while grinding it down to the pulpal outline in order to achieve a more complete fixation. Three other teeth extracted at this time were not considered acceptable £or the study. Sufficient histologic detail for evaluation was lacking in two and another was disc~rded because the pulpal chamber was perforated upon exposing the pulp. The importance or serial sectioning is well illustrated in this ex~1ple as one section shows an intact lower pulp chamber while in another the perforation . -40- is obvious and shows a peri-coronal granuloma (Figures 9 and 10). Prior to sacrificing one animal, the pulps o£ two unoperated teeth were exposed in essentially the same manner as the other pulps. One pulp remained exposed £or one-hal£ hour and the other for one hour. They were then extracted, prepared for histologic study, and serially sectioned. Brown and Brenn stained sections were negative for bacterial contamination .• Histologic Evaluation o£ Deciduous Teeth 30 Days Following Treatment. The pulps o£ nine deciduous teeth were exposed and treated in essentially the same manner as were the permanent teeth. The only difference being that each ex­ posure was made on the occlusal surface. This was necessary due to severe attrition which had sharply reduced the clinical crown height thereby making class V preparations impractical. Many complications were encountered with the deciduous · teeth. Two teeth which were badly £ragmented' during ex­ traction could not be microscopically studied. Advanced physiological root resorption distorted the histologic picture o£ two others and three teeth exhibited pulp polyp £ormation in the cavities from which restorations had been lost. -41- At the time of extraction six of nine r e storations had been lost and the other three were loose. In order to correctly evaluate the pulps treated with the two capping materials an effective seal of the preparation was con­ sidered to be essential. Since the restorations were lost and there was not an adequate .seal of the cavity, and in view o£ the previously mentioned complications, there was considerable doubt as to the reliability of the histologic interpretations. A decision was made to eliminate from the study the results fox the deciduous teeth. Histologic Evaluation o£ Permanent Teeth 90 Days Followin2 Treatment. An inflammatory response o£ varying degree was seen at the exposure site in each of 26 pulps evaluated 90 days following treatment. Ten o£ 13 pulps treated with the antibiotic preparation were considered to have a mild to moderately inflamed pulp (Figure 11). The remaining three showed severe inflammation with abscess formation. In one of these a substance thought to be the zinc oxide - eugenol dressing was observed adjacent to the pulp tissue (Figure 12) • . The pulps treated with the starch control were in sharp contrast to the majority of those described above. Twelve of the thirteen specimens were severely inflamed -42- o~ necrotic, (Figu~e 13). All but two o£ those demon­ st~ated abscess £o~mation and nec~osis ~anging £~om pa~tial to complete (Figures 14 and 15)~ Substantial amounts o£ reparative dentin were de­ posited in all but one o£ the pulps treated with the anti ­ biotic compound. Only £our o£ 13 pulps treated with the starch control showed substantial deposits o£ dentin and the great majority showed minimal ox negligible amounts. The relative in£lammato~y and ~eparative status o£ the antibiotic t~eated pulps was decidedly better than those treated with the starch control. In addition to the 26 teeth previously described, two othe~s were ext~acted at this time which could not be histologically evaluated. Due to sectioning difficulties the exposures could not be seen entering the pulps. TABLES AND ILLUSTRATIONS -43- PREFACE TO TABLES I AND II A. Method of exposux e j ·x e£ ex s to the method by which entxance was made into the pulp. 1. EP -- exploxex point. 2. HSB -- high speed bux, :rotating at maximum speed, undex · appxoximately 30 pounds o£ aix pxessuxe. 3. SSB -- slow speed bux. B. Reparative dentin £ormation; refers to the £ormation of xep~xative dentin on the walls o£ the chamber, canal, and around the dentin chips in the vicinity of the exposure. 1. Large amount -- present in abundance with an attempt at bridging by a coalescence £xom several niduses. 2. Modexate amount -- a smaller amount of dentin is pxesent and coalescence is less pronounced. 3. Small amount -- much less foxmation with little coalescence. 4. Negligible amount -- minimal ox none. C. Inflammatory status o£ the pulp. 1. Mild -- the inflammation is limited to the im­ mediate vicinity of the exposuxe site with an -44- excellent attempt by the pulp to form a connective tissue barrier to minimize further pulpal involvement. The inflammatory cells are primarily chronic in nature and are relatively few in number. The remainder of the pulp is relatively normal. 2. Moderate the inflammation has extended beyond the immediate exposure but is still limited to the coronal portion o£ the pulp and there is a positive attempt by the pulp to minimize severe pulpal involvement~ The inflammatory cells are primarily chronic in nature and are relatively few in number. The remainder of the pulp is relatively normal. 3. Severe -- the inflammation is widespread and has penetrated to the deeper portions of the pulp with a heavy concentration of mixed inflammatory cells. The inflammatory picture is relatively quite severe. Abscess formation · is frequently seen. 4. Partial necrosis necrosis is widespread but there is some vital tissue remaining. s. Complete necrosis -- the pulp is completely . -45- necrotic and peri-apical lesions are sometimes seen. D. Pulpal reaction; refers to the comprehensive health status of the major portion of the pulp and its response to the insult. 1. Satisfactory -- the major portion o£ the pulp is healthy and the potential fox complete resolution of the insult is thought to be good. 2. Unsatisfactory by reason of severe and extensive inflammation -- the insult has produced an over­ whelming inflammatory picture and it is thought that the potential fox healing is not very good. 3. Unsatisfactory by reason of extensive necrosis it is thought that prospects fox healing are greatly diminished and practically nil. -46- TABLE I Histologic Results fo~ Pulps o£ Pe~manent Teeth T~eated with the Antibiotic Compound No. Tooth Method of Repa~ative Inflammatory Pulpal Exposure Dentin Status of Reaction Formation Pulp Animal Number I 30 Days 1. ULl EP Large Mild 1 2 .. UL2 EP Large Mild 1 3. UL6 HSB Moderate Moderate 1 4. LRl EP Large Mild 1 5. LR2 EP Moderate Moderate 1 6. LL7 HSB La~ge Mode~ ate 1 7. LR6 HSB Mode~ ate Mode~ ate 1 Animal Number II -- 30 Days 8. URl. EP Large Moderate 1 9. UR2 EP La~ge Mild 1 10. LLl SSB Large Mild 1 11. UL2 EP Large Mild 1 12. LL7 HSB Moderate Mild 1 13. LR6 HSB La~ge Moderate 1 Animal Number III -- 90 Days 14. URl EP Small Severe* 2 15 .. UR2 EP Large Moderate 1 . 16. UR5 HSB Mode~ ate Mild 1 17. UR6 HSB Large Mild 1 18. UL3 EP Moderate Moderate 1 19. UL4 HSB Moderate Moderate 1 20. UL7 HSB La~ge Moderate 1 21. LLl EP Moderate Severe* 2 22. LL2 EP Mode~ ate Moderate 1 23 .• LL5 HSB Large Moderate 1 24. LL6 HSB Large Severe* 2 25. LR3 HSB La~ge Mild 1 26 .. LR7 HSB La~ge Moderate 1 Note: Evaluations could not be made on three other permanent teeth treated with this preparation Symbols *------Abscess Fo~mation #------Pe~i-apical · Lesion C------Complete P------Paxtial Numbers 1------Satisfacto~y 2------Unsatisfactory (inflammation) 3------Unsatisfactory (nec~osis) -47- TABLE II Histologic Results £or Pulps o£ Permanent Teeth Treated with the Starch Control No. Tooth Mode o£ Reparative In£lam'ma tory Pulpal Exposure Dentin Status o£ Reaction Formation Pulp Animal Number I 30 Days 1. URl EP Neg. 2. UR2 EP Neg. 3. UR6 HSB Small 4. UR7 HSB Neg. 5. LLl EP Moderate 6. LL2 EP Neg. 7. LR7 HSB Moderate Animal Number II -- 30 Days 8. ULl EP Moderate 9. UL6 HSB Large 10. LL2 EP Small 11. LRl EP Neg. 12. LL6 HSB Small 13. LR7 HSB Large Animal Number III -- 90 Days 14. ULl HSB Neg. 15. UL2 HSB Neg. 16. UL5 HSB Neg. 17. UL6 HSB Large 18. UR3 EP Neg. 19. UR4 HSB Neg. 20. UR7 HSB Neg. 21. LL3 EP Neg. 22. LL4 HSB Small 23. LL7 HSB Moderate 24. LRl EP Moderate 25. LR2 HSB Moderate 26. LRS HSB Neg. Note: Evaluation could not be permanent teeth treated Symbols *-----Abscess Formation #-----Peri-apical Lesion C-----Complete P-----Partial Severe* 2 Necrotic-C 3 Severe·* 2 Severe·X· 2 Severe 2 Necrotic-C 3 Mild 1 Severe·* 2 Moderate 1 Mild 1 Necrotic-C 3 Severe* 2 Mild 1 Severe·* 2 Necrotic-P 3 Necrotic-C# 3 Moderate 1 Severe* 2 Necrotic-P# 3 Necrotic-C# 3 Severe* 2 Necrotic-C# 3 Severe* 2 Severe* 2 Severe 2 Severe* 2 made on two other with this preparation. Numbers 1-----Satisfactory 2-----Unsatisfactory (inflammation) 3-----Unsatisfactory (necrosis) -48- Figure 1. Photograph demonstrating typical surgically exposed pulps. -49- Figure 2. Microscopic section of a mandibular left central incisor. The pulp had been left open £or 24 hours following exposure. Clusters of microorganisms are seen scattered throughout the exposure area. Brown and Brenn X 28. -50- Figure 3. Microscopic section of a maxillary left central incisor treated with the anti- biotic pxeparatio?, 30 days postoperatively, showing inflammation limited to the immediate vicinity of the exposure. Hematoxylin and eosin X 28. Figure 4. Microscopic section o£ a maxillaxy right lateral incisor treated with the starch con­ trol, 30'days postoperatively, showing a severe inflammatory response, abscess formation and negligible amount·s o£ repara­ tive dentin. Hematoxylin and eosin X 28. -51- Figure 5. Microscopic section o£ a maxillary right central incisor treated with the starch control, 30 days postoperatively, exhibiting complete necrosis. Hematoxylin and eosin X 28. Figure 6. Microscopic section o£ maxillary left lateral incisor treated with the anti ­ biotic preparation, 30 days postoperatively, showing good alignment o£ dentin chips contributing to the bridging attempt. Hematoxylin and eosin X 28. · -52- Figure 7. Microscopic section of mandibular right latexal incisox treated with the anti~ biotic preparation, 30 days postoperatively, demonstrating a thin band of epithelium across the exposure site. Hematoxylin and eosin X 28~ Figuxe 8. Micxoscopic section o£ a maxillaxy left lateral incisox treated with the antibiotic preparation, 30 days postoperatively, showing distortion attxibuted to incomplete fixation by being left out of £oxmalin for 12 hours. Hematoxylin and eosin X 28. -53- FiguLe 9. Microscopic section o£ a mandibular left £iLst molaL showing a peLicoronal gLanu­ loma Lesulting £Lom a peL£oration o£ the pulp chambex. Hematoxylin and eosin X 28. FiguLe 10. MicLoscopic section o£ the same tooth demonstrating the need £ox seLial sections. Hematoxylin and eosin X 28. -54- Figure 11. Microscopic section o£ a maxillary xight second premolar treated with the anti ­ biotic preparation, 90 days postoperatively, with inflammation limited to the exposure site and pulp horn. Hematoxylin and eosin X 28. Figure 12. Microscopic section of a mandibular left central incisor treated with the anti ­ biotic preparation, 90 days postoperatively~ showing a substance thought to be zinc oxide - eugenol adjacent to the pulp. Hematoxylin and eosin X 28. -55- Figure 13. Microscopic section of a maxillary 'left central incisor treated with the starch control, 90 days postoperatively, showing a severe inflammatory response. The void at the exposure represents an artifact formed by a pulling away of the tissue and if pushed back would fit as in a jig saw puzzle. Hematoxylin and eosin X 28. Figure 14. Microscopic section of a maxillary left second premolar treated with the starch controlJ 90 days postoperatively, showing a necrotic apex and a fistulous tract. Hematoxylin and eosin X 28. -56- Figu~e 15. Microscopic section of a maxillary right second molar t~eated with the starch cont~ol, 90 days postoperatively, showing some vital tissue remaining and a pro­ nounced calcific response at the apex. Hematoxylin and eosin X 28. Figure 16. Photographs demonstrating intra oral palatal lesions, 90 days postoperatively, opposite the uppe~ right second molar and the upper left second premolar. -57- Figure 17. Photograph demonstrating intact restorations 90 days postoperatively. Figure 18. Photograph demonstrating an intra oral vestibular lesion, 90 days postoperatively, opposite the lower left first premolar. DISCUSSION -58- It has been demonstrated in this study that the ex- posed pulps o:f monkey teeth became infected when le:ft open to the oral environment fox a period o:f 24 hours. The microorganisms appeared to be predominantly gram-positive cocci and they were concentrated primarily at the exposure site. They did not appear to have significantly. penetrated the remaining intact pulp tissue very much. 28 (Figure 2). A study by Kiryati indicated that the severity of the infection was increased by leaving the pulps open for longer 42 periods o:f time. Seltzer and Bender also support this observation by commenting that the longer the time of exposure, the greater is the likelihood that the microorganisms will gain a :foothold in the injured tissue. 29 In an experiment by Kakehashi et al pulp exposures were made in the teeth o:f rat molars and left open to the oral environment for :from 1 to 42 days. The sample consisted of germ-:free and conventional rats. Eighteen of 21 teeth in the germ-free group . survived the very traumatic operative procedure. In some instances the pulp chambers were per- £orated and yet the pulp survived. They showed calcific bridge formation o:f a varying degree and inflammation was minimal in all cases. All o:f the pulps exposed in the con- ventional rats terminated in pulpal death and abscess -59- £ormation was s e en without exception when sections were taken £rom specimens after eight days. The results em- phasize the important role that microorganisms play in pulpal pathosis and the evidence strongly suggests that they axe the dominate· etiological £actor. In this study a high priority must be given to the role of bacteria when one attempts to explain the marked difference in results o£ those pulps treated with the antibiotic pre- paration and those with the starch control. A logical assumption would be that the presence o£ microorganisms constituted one known common denominator which stood to be affected differently by the two experi'mental preparations. The results indicate that the antibiotic compound largely succeeded in suppressing bacterial activity whereas the control did not. The starch control material used in this experiment 38 was identical to that used by Mullaney et al. In the latter study the pulps of monkey teeth were surgically ex- posed and incidentally were left open during the operation £ox about one-hal£ hour. Microscopic evaluation showed the major portion o£ the pulp abnormal in only two o£ 14 speci­ mens treated with the starch control. The results £ox the control treated teeth axe strikingly different £xom those -60- o£ this study in which 21 of 26 pulps so treated exhibited severe inflammation, abscess £ormation, ox necrosis. The major variation in the experimental procedure was the amount of time the pulp was left open to the oral environ- ment, and the £act that salivary bacterial contamination was inevitable in this study, and unlikely in the foxmex. In this study two teeth which were not to be used in the study were surgically exposed and left open £ox one-hal£ and one houx respectively. Bacteria could not be demon~ stxated in either pulp when Brown and Brenn histologic sections were made, even though saliva was introduced into the pulp on the tip o£ an explorer. Thus, the magnitude of bacterial contamination appears to account fox the significant disparity in results between the two studies. A possible relationship is thought to exist between the inflammatory status o£ the pulp and the amount o£ reparative dentin deposited. Moderate to large amounts were consistently seen in mild to moderately inflamed pulps and negligible to small amounts found in severely inflamed ox necrotic pulps 9,28,29 (F . 3 th~ouah 15) Othe~s have made simila~ ~guxes ~ _ · ~ ~ observations. The amount of reparative dentin seen in necrotic pulps may be an indication of the time of pulpal degeneration and -61- death. A necrotic pulp with a negligible amount may have died rather soon after treatment whereas one ex­ hibiting a large deposition possibly survived for a longer period of time. This was a fairly consistent pattern and three teeth which showed clinical evidence of necrosis when evaluated at 30 days presented a comparable histo­ pathological picture at 90 days. Negligible amounts of reparative dentin were present suggesting that a correlation did exist between the time of death and the amount present (Figures 15, 16 and 17). This could be checked readily in future studies by using a vital dye marker to demarcate the reparative from primary dentin. Dentin chips which had been introduced when the pulp was exposed contributed significantly to the degxee of calcific bridging seen in the study. Large amounts of reparative dentin formed about them often coalescing with that around other chips and with depositions on the walls to create an attempt at bridging (Figure 6). This phenomena was frequently observed in the antibiotic treated pulps and rather infrequently in those treated with the starch control. The arrangement and alignment of the chips appeared to be quite important with regard to the degree of bridging. -62- Complete bxidging was not seen in any specimen in this study. Howevex it appeaxed that specimens demon- stxating incomplete bxldging, with vigoxous calcific xepaix, would possibly pxoceed to completeness if the pulp wexe to suxvive fox a longex indetexminate pexiod o£ time. (Figuxe 3- 6). Although calcific bxidging is not considexed to be an absolute indication of success in pulp capping ox pulpotomy it would appear to be a desixable featuxe in that it may serve to pxevent ingxess of oral fluids in the event of leakage around a xestoxation. Fioxe-Donno and 32 Baume noted that lack of a solid barrier was a consistent finding in pulps txeated with cortico antibiotic preparations and considexed this to be an objectionable and undesirable 38 trait. Mullaney et al did not see complete bridging in specimens obtained after 90 ox 180 days. In this study thexe were deviations fxom noxmal established pattexns. One such instance was the presence of a thin band of epithelium covering the exposure site (Figuxe 7). This possibly represents the same phenon1ena by which a pulp is epithelialized and protected. It is thought that in this case the epithelium was inadvertently intro- duced by the bur duxing the exposure proceduxe since proximity to the gingiva was very close. . -63- Other factors which may have influenced results were considered to be leakage around restorations, resistive differences among the individual animals, a mix up resulting in the wrong medication being placed, .excessive damage while exposing, and in placement of the medications. The composition of the antibiotic compound used in this study was basically the same as that used in three other 36,38,39 studies. The exception being that the glucocorticoid was omitted in this experiment. The drugs were chosen pri- marily £or their mutual compatibility with one another and their broad spectrum coverage. 43 A study by Bowen on the salivary flora of Macaca Irus 44 and one by Kelly on the Macaca Mulatta indicate that the oral flora in the monkey is quite similar to that o£ man~ Thus it is reasonable to assume that they would be susceptible to antibiotic therapy employed :for man. 45 Kane states that the principles involved in the handling o£ any infection, whether present in the oral cavity or else- where, are very similar i£ one makes allowances for certain anatomic peculiarities. One of the principles that should be.adhered to in antibiotic therapy is directed towards controlling the invasive features in an endeavor to limit -64- the infection to the area supporting the portal of entry. The author commented that success or failure will depend upon the attainment of an effective antibiotic level in the blood and area of infection. These principles would certainly be applicable to a pulp capping procedure and one can readily see the importance of an adequate application and proper placement of the medicament. It was often very difficult to do in this study,- especially in the small lower incisors, and this may possibly be responsible for some of the failures seen in the antibiotic treated teeth. Such may have been the case in one instance in which it appeared histologically that the pulp was in direct contact with a material thought to be the zinc oxide and eugenol restoration indicating that placement was faulty (Figure 3). In others the quantity of the medication carried to place may have been insufficient. Of note, is the £act that all of the severe inflammatory responses observed in teeth treated with the antibiotic preparation, occurred in the first anin1al operated. This could be the result o£ inadequate placement, as it was felt that proficiency in placing the materials increased as more teeth were treated. 47 Kane also theorized that an adequate level should be attainable in any area by parenteral administration i£ -65- sufficiently high doses are e mployed and therapy con­ tinued £or a prolonged period o£ time. It was pointed out that when local therapy is used, antibiotic solutions, in order to be effective, must be kept in contact with the infected tissue long enough to allow the antibacterial action to exert itself. When bacteria are exposed to antibiotic agents there is a lag period of several hours before bacteriostatic activity can be observed. Parenteral therapy is thought to be necessary when infection is present deep within the tissue. The results of the present study are encouraging, how­ ever the possibility exists that we are witnessing only a partial realization of the maximum potential of antibiotic therapy. It is doubtful that the procedure used in this experiment fully satisfies the principles of antibiotic therapy. This is particularly so with regard to the presence of an effective antibiotic level in the area o£ the infection. It may well be that a frequent change of dressings and/or adjuntive administration of systemic antibiotics would prove to be beneficial in a future pulp capping study in which antibiotics were to be used. In this study a mild or moderate .degree of inflammation was evident in the great majority o£ the specimens treated -66- with the antibiotic pxepaxation. Mild to modexate in­ flammation was also seen in five teeth txeated with the staxch contxol. Thxee teeth txeated with the antibiotic pxepaxation exhibited sevexe inflammation with abscess foxmation 90 days postopexatively, suggesting a slight txend towaxds a moxe sevexe inflammatory pictuxe· at 90 days postopexatively than at 30 days. Howevex, the duxation of this expeximent is inadequate to evaluate success ox failuxe and there axe no indications at this time by which it can be accuxately pxedicted that the txeated pulps will pxoceed to degenexation and necxosis. Indeed, considexing the extensive damage and bactexial con~amination pxoduced by the exposure the pulps have shown evexy indication of a xobust attempt to suxvive. SUMMARY AND CONCLUSIONS -67- Pathogenic microorganisms axe considered to play a prominent role in the initiation o£ pulpal pathology when the vital dental pulp is exposed. There is evidence to indicate that the presence of bacteria is the most significant factor in prohibiting healing. The histologic results of a pilot study indicated that infection of a significant degree occurred when the pulps of four central incisors of a Macaca mulata monkey were surgically exposed with a bur ox an explorer and left open to the oral environment fox a period of 24 hours. The teeth were then extracted, serially sectioned, and micro­ scopically examined. Microorganisms were observed in the immediate vicinity of the exposure area and were identified by a Brown and Brenn stain which is a differential stain fox demonstrating bacteria in tissue sections. The review of the literature described many experiments in which antibiotics had been used to cap exposed pulps. It was felt that additional investigation into this area was warranted since the results tended to be conflicting and inconclusive. This modified double-blind investigation was ~ndertaken to examine the hypothesis that £or any given species, the utilization of an antimicrobial agent, innocuous to healthy tissue, yet potent enough to destroy or control the invasive -68- pathogenic organisms, would allow the natural defense mechanism o£ a vital pulp to overcome the ' infection, repair the drunage, and survive. In the principal portion o£ the investigation the pulps o£ 57 permanent teeth £rom three monkeys were surgically exposed in essentially the same manner as in the pilot study. After remaining open £or 24 hours a modified double­ blind procedure was used in which the exposed pulps were capped with the experimental antibiotic material or the pure starch control. The antibiotic pxeparation consisted of erythromycin estolate 10 percent, streptomycin sulfate 10 percent, and starch q.s. as the vehicle. A zinc oxide - eugenol restoration with zinc acetate crystals was inserted following placement of the capping material in order to seal the cavity. It is very significant that all of the class V zinc oxide - eugenol restorations in the permanent teeth were in place and apparently intact when examined just prior to the sacrifice of each animal. However six o£ nine occlusal zinc oxide - eugenol restorations in the deciduous teeth had been lost and the other three had been dislodged and were loose. Twenty-nine permanent teeth and nine deciduous teeth were extracted for histological study 30 days following treatment. -69- The nine deciduous teeth were discarded from the study as it was felt that the lost and loose restorations would prevent an accurate histologic evaluation. Three permanent teeth were also considered unacceptable for the study. In two of these teeth the laboratory technician was unable to find the exposure entering the pulp chamber while sectioning. The other was discarded because the bur had perforated the lower portion of the pulp chamber during the expo~ure procedure. Twenty-six of the 29 permanent teeth extracted 30 days following treatment were considered to be acceptable for the study. Thirteen had been treated with the antibiotic pulp capping material and thirteen with the starch control. All of the antibiotic treated teeth experienced a favorable pulp reaction with only a mild to moderate amount of in­ flammation present and moderate to large amounts of reparative dentin deposited. In contrast nine of 13 teeth treated with the starch control exhibited a severe pulp reaction with severe in­ flarr.m1ation present and only small to negligible amounts of reparative dentin deposited. The histologic results at 30 days indicated that the pulp responded much more favorably to the antibiotic capping -70- material . than to the starch control capping material Twenty-eight permanent teeth were extracted £ox histo­ logical. study 90 days following treatment. Two o£ this number were unacceptable £or the study because the laboratory technician was unable to find the area o£ exposure between the preparation and the pulp while sectioning. Twenty-six o£ the 28 permanent teeth were considered to be acceptable £ox the study. Thirteen had been treated with the antibiotic pulp capping material and 13 received the starch control. Ten o£ 13 teeth treated with the .anti ­ biotic preparation experienced a favorable pulp reaction, with mild to modexate inflammation and substantial amounts of reparative dentin present. The other three teeth treated with the antibiotic compound showed a severe inflammatory picture with abscess £ormation and small to large deposits of reparative dentin. In sharp contrast, 12 o£ 13 teeth treated with the starch control exhibited a very unsatisfactory pulpal reaction. Eleven o£ 13 teeth demonstrated abscess £ormation ox partial to · complete necrosis. Small to negligible deposits o£ reparative dentin were usually seen in these teeth. The histologic result at 90 days continue to indicate that the pulp experienced a much more favorable response -71- to the antibiotic capping material than to the starch capping agent. There appeared to be a slight trend towards a more severe inflammatory picture 90 days postoperatively than at 30 days postoperatively in those teeth treated with the antibiotic capping material. However it would be hazardous to predict the fate of those teeth based on the histologic picture present at that time. The elements for repair were evident in most of the pulps and the potential for resolution o£ the insult appeared to be quite good. It was felt that a prediction of success or failure could not be justified. There appeared to be a relationship between the extent of bridging and the arrangement of dentin chips around the exposure site. It was observed that a better alignment of dentin chips appeared to enhance bridging. Complete bridging was not seen in this study although it appeared to be still possible if the pulps survived for a longer period o£ time and reparative dentin continued to be deposited. The results of this study would seem to corroborate 29 the findings of Kakehashi et al to a high degree in that they suggest that microorganisms do play a major role in preventing healing following vital pulp exposure. The principles of antibiotic therapy should be given careful consideration in any future antibiotic pulp study, -72- e specially with regard to the importance o£ achieving and maintaining a high concentration o£ . the drug in the area o£. infection. It is questionable that this was accomplished to the highest possible degree in this study. It may prove beneficial in future studies to frequently replace the antibiotic capping material £or the first few days o£ treatment or to administer the antibiotic systemically in order to achieve a high concentration of the drug within the pulp chamber. A histological investigation o£ longer duration using this antibiotic capping material is warranted in view o£ the encouraging results obtained in this study. REFERENCES . . -73- 1. Quarterly Cumulative I1 dex Medicus: 32: 589, 1942. 2. Index to Dental Literature: 1942-1944: 235-236. 3. Bonner, A. B.: Preserving vitality in pulp exposed teeth. D. Survey 23: 1069, 1947. 4. Kutscher, A. H.: Penicillin sodium capping of vital cariously exposed pulps in adults. D. Digest 56: 388-393, 1950. 5. Webb, C. S.: D. Survey 26: Control pulpal infection with penicillin. 343-344, 1950. 6. Gilberg, S. L.: Penicillin pulpal therapeutics. U. s. Armed Forces Med. J., 2: 203, 1951. 7. Rosen, L. J.: Deciduous pulp capping: its present status and a report on penicillin pulp therapeutics. J. Missouri D. A., 32: 11, 1952. 8. Amler, M. H.: Control of pulpitis by means of systemic antibiotic therapy. J. D. Res., 33: 737, 1954, Abstract. 9. James, V. E., Englander, H. R., and Massler, M.: Histo­ logic response of ru~putated pulps to calcium compounds and antibiotics. Oral Surg., Oral Med., and Oral Path. 10: 97 5' 1957. 10. Kutscher, A. H. and Yigdall, Irene R.: Bacteriologic evaluation of the compatibility o£ antibiotics and other therapeutic agents. Oral Surg., Oral Med., and Oral Path. 5: 1096-1098, 1952. 11. Ramnarine, D. C.: Treatment of infected dentin and pulps of children's teeth with Terramycin. D. Survey 32: 1465-1466, 1956. 12. · Seltzer, S. and Bender, I. B. : Some influences affecting repair of the exposed pulps o£ dog's teeth. J. D. Res. 37: 678-687, 1958. 13. Maeth, H.: Saving o£ dental pulps with oxytetracycline. D. Digest 65: 1921, 1959. -74- 14. Burke, G. W. and Holmes, T. K.: Effect of local anti ­ bacterial agents on bacteria in dental pulps of rats. J.D. Res., 41: 1105, 1962. 15. Bur~an, N. Weir: A preliminary report of an investi ­ gation to study the effectiveness of certain drugs for steri~izing carious dentine. Oral Surg., Oral Med., and Oral Path. 7: 647-657, 1951. 16. Roth, L. fl.: Aureomycin as applied to deciduous teeth. New York J. Den. 22: 213, 1952. 17. Lepine, P., Barskl, G., and Maurin, J.: Action of chloromycetin and of aureomycin on normal tissue cul­ tures. Proc. Soc. Exper. Biol. and Med. 73: 252-255, 1950. 18. Rob er ts, R. M.: Adjunctive use of IM penicillin injections in treatment of exposed pulps. J.A.D.A., 46: 171-173, 1953. 19. Seelig, Alex, Fowler, R. C. and Tanchester, D.: The effects of penicillin G potassium plus calcium carbonate on surgically exposed pulps of the Rhesus monkey. J.A.D.A., 48: 532-537, 1954. 20. Via, W. F. Jr.: Barium sulfate and antibiotic mixture in pulpotomy. J. Den. Children, 22: 195, 1955. 21. Englander, H. R. Massier, M. and Carter, W. J.: Clinical evaluation of pulpotomy in young adults. J. Den. Children, 23: 48, 1956. 22. Feitelson, N.: Pulp capping with calcium hydroxide and penicillin. J. Den. Children, 23: ' 214, 1956. 23. Gollob1·n A · Ant1"biotic sedative base. D. Survey, 33: ' .. 1464, 1957. 24. Sanders, D. J.: Pulp conservation with an antibiotic agent. J. Den. Children, 26: 316-317, 1959, abstract. 25. Shay, D. E., Sarvbin, L. D., Spurrier, H. S. and Sanders, D. J.: Pulp conservation with an antibiotic agent. J. Den. Children, 27: 5, 1960. -75- 26. Gardner, A. F., Thomson, J., Warren, G. and Young, D.: Preliminary report on high speed pulp~l exposures capped with neosporin. J.D.A. So. Africa. 17: 248- 259, 1962. 27. Sidky, E.: Combined hydrocortisone-omnacillin-calcium hydroxide therapy in pulpotomy. Egyptian D. J., 3: 9, 1957. 28. Kiryati, A. A.: The effect of hydrocortisone plus polyantibiotics upon the damaged and infected dental pulp of rat molars. J. D. Res., 37: 886, 1958. 29. Kakehashi, S., Stanley, H. R., and Fitzgerald, R. J.: The effects of surgical exposures of dental pulps in germ-free and conventional laboratory rats. Oral Surg., Oral Med., and Oral Path. 20: 340-349, Sept., 1965. 30. Kiryati, A. A.: Streptokinase in combination with antibiotics and cortisone in the treatment of exposed pulps of rat molars. I.A.D.R., 40: 23, 1962, abstract. 31. Schroeder, A. and Triadan, H.: The ·pharmacotherapy of pulpitis. Oral Surg., Oral Med., and Oral Path~, 15: 345, 1962. 32. Fiore-Donno, G. and Baume, L. J.: Effects of capping compounds containing corticosteroids on the human dental pulp. Helvetica Odont. Acta, 6: 23, 1962. 33. Osen; Paul: Clinical experiences with a cortico-anti ­ biotic preparation in conservative tre~tment of the pulp. J. Canad. D. A., 30~ 771-775, 1964. 34. Mager, M. E.: Treatment of pulpitis with synthetic steroids combined with antibiotics. A review and results of a pilot study. D. Pract. and D. Record, 14: 505, 1964. 35 Ehr E H · The effect of triamcinolone with tetra-. man, . . . cycline on the dental pulp and apical periodontium. J. Pros. Dent., 15: 144-152, 1965. 36. Lawson, B. F. and Mitchell, D. F.: Pharmacologic treat­ ment of painful pulpitis. Oral. Surg., Oral Med. and Oral Path., 17: 47, 1964. -76- ~ 37. Baume, L. J.: Mioglichkeiten und grenzen der vitolerhaltung der entzundeten pulps. Schweizerische Monatsschri£t fur Zahnheilkunde, Band 75 NR 10: 1085, 1965 . . 38. Mullaney, T. P., Lawson, B. F., and Mitchell, D. F.: Pharmacologic treatment of pulpitis: A continuing investigation. Oral Surg., Oral Med. and Oral Path., 21: 479, 1966. 39. Schneider, H. S. and Lawson, B.: Corticoid antibiotic n1ixture compared to calcium hydroxide for capping exposed pulps in human primary teeth. IADR abstracts, No. 443, pg. 150, March 1966. 40. Brown, J. H. and Brenn, L.: A method for the differential staining of gram-positive and gram-negative bacteria in tissue sections. Bull. of John Hopkins Hosp. 48: 69, 1931. 41. Stanley, H. R.: Personal communication. 42. Seltzer, S. and Bender, I. B., editors: The Dental Pulp. Philadelphia and Montreal, J. B. Lippincott Company, 1965. 43. Bowen, W. H.: The salivary flora of Macaca Irus. British Dental Journal 115: 252-254, 1963. 44. Kelly, F. C.: Bacteriology of artificially produced necrotic lesions in the oropharynx of the monkey. J. Infect. Dis., 74: 93, 1944. 45. Kane, L. W.: Role of penicillin and streptomycin in oral infections. Am. J. Orthodont. and Oral Surg., 33: 395-400, 1947. CURRICULUM VITAE July 1, 1931 1951-1955 1956 1955-1958 1958-1962 1962-1964 1963-1964 1963-1964 1964-1966 G. Richard Baker Born in Covington, Kentucky United States Navy Married Sydney Carolyn Fitch B. S., University of Kentucky, Lexington, Kentucky D. M. D., University of Louisville School o£ Dentistry, Louisville, Kentucky General practice of dentistry Instructor, University of Kentucky College of Dentistry, Lexington, Kentucky President, Central Kentucky Study Group o£ Dentistry for Children M. S. D., Graduate Program, Indiana School o£ Dentistry, Indianapolis, Indiana Professional Societies American Dental Association American Association of Dentistry for Children Kentucky Dental Association Delta Sigma Delta Fraternity ABSTRACT ) Topical Antibiotic Treatment of Infected Dental Pulps of Monkeys By: G. Richard Baker Indiana University School of Dentistry Indianapolis, Indiana A modified double-blind method of investigation was used in which the pulps of 52 monkey teeth were surgically exposed and left open to the oral environment for a period of 24 hours. One-half of the exposed pulps were treated with an antibiotic preparation and one-half with a pure starch control. The antibiotic compound consisted o£ erythromycin estolate 10 percent, streptomycin sulfate 10 percent, and starch q. s. as the vehicle. The teeth were extracted at 30 and 90 day intervals after treatment and histo.logically evaluated. Inflammation of a varying degree was observed in all of the teeth treated with either the antibiotic preparation or the starch control. However, those teeth treated with the antibiotic capping material exhibited much less inflammation than did the great majority of teeth treated with the starch control, in which abscess £ormation and necrosis were frequently observed. The pulps of those teeth treated with the antibiotic capping material demonstrated a decidedly more favorable reaction than did those pulps treated with the starch capping material. Calcific repair at the exposure site was not observed to be complete in any instance. The histologic findings for the antibiotic treated teeth were encouraging and warrant additional investigations of longer duration.