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and the problems associated with all of them, a three dimensional leakage study was carried out comparing amalgam, Super EBA and MTA using a fluorescent dye and confocal microscopy. The results show amalgam and Super EBA both leak through to the underlying gutta percha (4mm), as has been shown previously, but the MTA only showed leakage four times out of ten and, in each of these cases, it leaked less than 1mm. Marginal adaptation was examined using Scanning Electron Microscopy showing that amalgam has a gap of 32~m, which is reduced to 19t~m when a varnish is used. Super EBA has a 10~.m gap, MTA has a gap of 2.8~m. From the ortho grade direction, which has been shown to be the reason for RCT failure, a novel approach to test for microleakage has been used. A tooth is prepared with an apicoectomy and retro-fill with one of the test materials such that bacteria can be introduced into the coronal aspect of the tooth and, if leakage occurs, media that the apex is suspended in will become contaminated. The apparatus is very technique sensitive, but initial results show that MTA behaves somewhat better than either amalgam or Su per EBA. Two types of in vitro cytotoxicity test have been carried out to date: agarose gel overlay inhibition and ~lCr release lysis testing. In both tests MTA performed considerably better than either amalgam or Super EBA. No in vivotests have yet been carried out. Anti-bacterial testing has shown that while, surprisingly, neither Super EBA nor amalgam had any antibacterial activity. MTA was active against all test organisms but Streptococcus Faecalis. Solubility and moisture sensitivity tests are incomplete, but MTA seems to compare favorably with amalgam and even seems to leak less after mixing in the presence of either saline or blood; however, the results are inconclusive at present. In clinical usage it is very easy to handle both while mixing and condensing. Histology after 4 months of healing have shown cementum bridge formation over the MTA retrograde filling. Although no long term followup studies have been carried out, several cases have been followed for at least a year showing good radiographic healing. In summary, although MT aggregate is not the ideal material, it shows initial promise and warrants further testing. However, the search for other materials and techniques needs to continue. Abstracted by Julian Moiseiwitsch, DDS, Graduate Endodontics, University of North Carolina School of Dentistry, Chapel Hill, N.C.
Scientific Session VI Management of Fascial Space Infections of Odontogenic Origin Jeffrey W. Hutter, DMD This session reviewed principles involved in the assessment and treatment of a patient with invasive 433
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odontogenic infection of the fascial planes. Of paramount importance in a case such as this is the identification of immediate, life-threatening signs that necessitate a referral. Examples of these signs include respiratory/ swallowing difficulty and CNS involvement. Differences between the bacterial species responsible for an acute and chronic infection were also discussed because the antibiotic regimen prescribed is dependent upon the stage of infection. A thorough examination and evaluation must be undertaken to arrive at an initial diagnosis. This is achieved by collecting historical data, clinical data and laboratory data. Historical data may be broken down into two categories: general factors and specific factors. General factors include age, alcohol/drug abuse, psychological state, family/social status and nutrition. Specific factors include pre-existing disease states, medications, allergies, antibiotic therapy and radiation treatment. Clinical data is obtained by assessing the patient's physical appearance, monitoring vital signs and performing a dental examination. Certain signs are indicative of the extent of the spread of infection, such as examination of the lymph nodes. The location of the lymphadenopathy may provide a clue as to the source of infection. Systemic involvement may manifest itself through symptoms such as dehydration or toxemia, which result in the patient's inability to function. Laboratory data includes culture and sensitivity of a specimen. General principles of anaerobic specimen collection and transportation media were discussed. After establishing the etiology of the infection, the next phase of treatment is eradication of the source through incision and drainage, possible root canal treatment, antibiotic therapy and supportive treatment. The seminar ended with a discussion of the indications, rationale and selection of antibiotics, concentrating on penicillin, penicillin/metronidazole and clindamycin. Abstracted by C.A. Koenig, DDS, Graduate Endodontics, Baylor College of Dentistry, Dallas, Tex.
Scientific Session VII HIV Infection: Patient Identification, Diagnosis and Management T.L. Green, DMD, MS, MEd This session highlighted the recognition and management of the HIV infected patient. A brief review of the epidemiology was presented. HIV infection is here to stay with estimates of 30 to 110 million cases worldwide expected by the year 2000. HIV infection represents a spectrum of disease exhibiting different stages. Of importance is the fact that these patients are infectious from the time of infection until they die. Methods of transmission were discussed with emphasis on how this may impact on dental care. Recognition of HIV infected patients was presented covering evaluation of patients'