Biomedical subjects
Publications and source records attributed to P C Reade.
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An abscess that developed following the extraction of periodontally involved teeth persisted after surgical drainage and ampicillin therapy. Subsequent culture of pus from this abscess gave a pure growth of Actinobacillus actinomycetemcomitans which was resistant to ampicillin. Surgical drainage and the use of appropriate antibiotic therapy cleared the infection. The identification of A. actinomycetemcomitans and the types of infection it causes are described. The probable mechanism of infection by the bacterium is discussed. A case that illustrates the importance of the microbiologic examination of pus from dental abscesses is reported.
An experimental model designed for the investigation of tooth transplantation immunobiology is presented together with the results of a long-term histological study of mature mouse tooth isografts transplanted to an intrabony site (tibial shaft medulla) and to an extrabony site (renal subcapsular site). Mature mouse mandibular third molars were isografted to the tibial shaft medulla and renal subcapsular kidney site in inbred C57BL/6 strain mice and observed histologically over a 6-month period. Isografts at both sites were observed to undergo initial pulpal degeneration with subsequent progressive regeneration as determined by post-transplantation dentine formation. Tibial shaft isografts were surrounded by bone and underwent progressive reabsorption beginning at the coronal dentine, exposed by occlusal wear prior to transplantation, while grafts to the subcapsular kidney site did not become surrounded by bone nor exhibit coronal resorption. Varying degrees of external root resorption and ankylosis of teeth transplanted to the intrabony site were observed, and signs of periodontal ligament reorganization were not seen in isografts at either site.
Fully developed mandibular third molar teeth, allografted across an H-2 plus multiple non-H-2 barrier to the tibial shaft medulla and renal subcapsular site in mice, were examined histologically over a 12-month period after transplantation. Cellular degeneration within the pulp chamber occurred in the immediate post-transplantation period and was followed by pulp chamber repopulation by a vascular fibrous connective tissue during the first 14 days after transplantation. Progressive regeneration of the grafts occurred and was characterized by irregular tubular dentine formation followed by more organized tubular dentine deposition on the pulp chamber walls. Allografts at both sites eventually underwent rejection, and it was apparent that grafts at the subcapsular kidney site were rejected in a shorter time (35 to 56 days) than those at the tibial shaft site (56 to 70 days). When mature teeth were allografted to the tibial shaft medulla across multiple minor (non-H-2) barriers alone, similar changes were observed with grafts undergoing rejection 56 to 70 days after transplantation. External root resorption and ankylosis were not prominent features and periodontal ligament reorganization was not observed in any of the grafts.
Mature mouse molar teeth were transplanted to the tibial shaft medulla across an H-2 plus multiple non-H-2 histocompatibility barrier. Over the 35-day experimental period, low levels of complement-fixing antibody were detected in the serum of recipients. Antibody was distributed over two peak periods, 6 to 11 days and 21 to 27 days after transplantation, with IgM apparently preceding IgG production.
Mature mouse mandibular third molars together with their periodontal ligaments and alveolar bone were isografted to two heterotopic sites: the renal subcapsular site and the tibial shaft medulla. The pulps and periodontal ligaments of the grafts underwent cellular degeneration after transplantation but demonstrated signs of revascularization and cellular repopulation 7 days after transplantation. Grafts obtained at 28, 60 and 100 days after transplantation demonstrated a significant decrease in the width of the periodontal ligament, a decrease in the number and organization of mature periodontal fibre bundles, the appearance of fibers arranged parallel with the root surface and a decrease in the thickness of surrounding alveolar bone. These regressive changes in the periodontal ligament were considered to be due primarily to the nonfunctional status of the teeth at the two heterotopic sites.
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The proliferation of bovine odontogenic epithelial (OE) and mesenchymal (OM) cells cultured in the presence of varying concentrations of epidermal growth factor (EGF) was examined. After a delay of two to three d, EGF-supplemented cultures contained significantly more cells than did controls. This effect was dose-dependent, was maximal at 10-9 g EGF/ml for OE and 10-8 g EGF/ml for OM, and was dependent on the presence of serum in the culture medium. The results suggest the possibility that EGF may play a role in the control of odontogenic cell proliferation in vivo.
This study was designed to provide a perspective of intraoral cancer, as it occurs in Victoria, by reference to the Central Cancer Registry of Victoria. Intraoral cancer was found to be a disease of males in the 50 to 69 years' age group. There was a low survival rate which appeared to be related to the aggressive nature of the disease and to the delays which often occurred before treatment was commenced. Therefore, a strong recommendation is made that clinicians, both medical and dental, increase their level of suspicion with regard to lesions of the oral mucous membrane in order to detect oral cancer at an early stage, and thereby to avoid the certain distress to patients which accompanies the management of advanced carcinoma of the oral mucous membrane.
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