An in vitro model system utilizing de-mineralized periodontium tissues was developed for investigating the molecular controls involved in the spatial deposition of minerals on collagenous tissues. Preferential mineral deposition was observed when the de-mineralized tissue sections were incubated in solutions containing a supersaturation of calcium and phosphate ions with respect to hydroxyapatite (HA). Energy dispersive X-Ray (EDX) analysis demonstrated that these minerals are likely to be octacalcium phosphate (OCP) or dicalcium phosphate dihydrate (DCPD); further characterization with a secondary technique is required to draw a more definitive conclusion. The role of collagen fibrils in mineralization was tested by removing all the non-collagenous components from the tissue sections with proteolytic enzymes and exposing them to similar mineralization conditions as the control samples. A substantially less amount of minerals were formed in these samples; this correlates well with the hypothesis in the literature that collagen fibrils alone cannot initiate mineral formation.

This study used vital bone markers to investigate mineralized tissue adaptation in the periodontium of rats after a hypothermic insult to their maxillary first molars. This hypothermic insult has been shown in previous studies to induce aseptic root resorption with variable effects on ankylosis. A secondary objective was to assess the pulpal changes that occurred concurrent with the changes in the periodontium. Four groups of 7, eight-week old male Sprague Dawley rats were assigned to be euthanased at the day 7, 14, 21 and 28 observation periods. At day 0, 4 groups of 6 rats were subject to a single 20 minute application of dry ice on their maxillary right first molar. The remaining 1 rat within each group did not receive the dry ice. All rats were given 2 sequential bone labels, calcein 5mg/kg and alizarin red 30mg/kg, administered intraperitoneally 8 days apart. The timing of the labels was such that all rats were euthanased 2 days after the last label. The rat maxillae were fixed in ethanol and embedded undecalcified in methylmethacrylate. Ten micrometre coronal sections were obtained through the furcation of the first molars with three of each group of ten consecutive sections being unstained, stained with von Kossa/ hematoxylin and eosin counterstain, or decalcified and stained with hematoxylin and eosin, respectively. Unstained sections were viewed under fluorescence, while transmitted light microscopy was used for the other sections. Mineral apposition rates along the bone, root and pulpal surfaces as well as periodontal ligament width were measured using histomorphometry. Semiquantitative measurements of the resorptive surfaces within the periodontium were also noted. Multivariate and negative binomial regression statistical analyses were used to identify influencing variables. A focal pattern of ankylosis was observed at days 14 and 21 in 3 rats and was not seen at day 28. In both the treated and control teeth, appositional activity was greatest along bone and least along the root surface. Mineral tissue apposition rates along the bone and root surface displayed an initial spike during day 14 but declined to levels of the control teeth by day 28. A longer time lag was observed with appositional activity in the pulp which also displayed a declining trend towards the control teeth values by day 28. Resorption levels along the root surface continued to remain significantly (p<0.0001) elevated. The significantly (p<0.0001) wider periodontal ligament width in the treated molars showed a declining trend towards that of the control teeth by day 28. There was a temporary disturbance of mineralized tissue adaptation on the bone and root surfaces with a recovery of cellular vitality within the periodontium and pulp and a trend towards homeostasis of the periodontal ligament width. The null hypotheses that a single prolonged thermal insult on a rat has no effect on mineralized tissue adaptation within the periodontium and pulp chamber and that the periodontal ligament width within the interradicular region does not change in response to thermal trauma induced by the present study were rejected. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1345386 / Thesis (D.Clin.Dent) - University of Adelaide, School of Dentistry, 2008

Three leaves of errata inserted before title page. / Bibliography: leaves 150-181. / xi, 181 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Determines whether growing cells of F. nucleatum ATCC 25586 could actually utilise peptides to provide the energy-yielding amino acid residues. Overall shows the important role of aminopeptidase in the nutrition and survival of F. nucleatum. / Thesis (Ph.D.)--University of Adelaide, Dept. of Dentistry, 1998

Doctor of Philosophy / Profound perturbation of epithelial structure is a characteristic feature of the immunopatholoical response to bacterial antigens considered to be central in the pathogenesis of the destructive lesion of periodontitis. The pathological basis for the disturbance of epithelial structure is not understood. It was demonstrated that the structural integrity and functional differentiation of the lining epithelium is compromised in relation to inflammatory changes associated with destructive periodontitis. In the pathological lining epithelium of the periodontal pocket there was a marked reduction of epithelial cadherin important in intercellular adhesion, of involucrin, a marker of terminal differentiation, and of the gap junction connexions that form intercellular communication channels. These changes were associated with alterations of filamentous actin expression, collectively indicating profound perturbation of epithelial structure. The data reported support the concept that the ability of the pathological lining epithelium to function as an effective barrier against the ingress of microbial products into the tissues is severely compromised (Ye et al., 2000). In addition, a recent study (Ye et al., 2003) by Western analysis of serum IgG from all 22 patients with chronic periodontitis tested indicated recognition of multiple epithelial components in individual patterns. In contrast, subjects with a healthy periodontium displayed only trace recognition of epithelial antigens. Levels of epithelial-reactive antibodies were significantly correlated with attachment loss as an indication of disease activity. To investigate a possible relationship between the bacterial flora adjacent to the diseased sites and the presence of epithelial-reactive antibodies, subgingival plague samples were taken from deep periodontal pockets and cultured anaerobically. Gram positive bacteria containing antigens potentially cross-reactive with epithelial cells were reproducibly isolated by probing membrane colony lifts with affinity-isolated (epitheial-specific) antibodies. The bacteria were identified as streptococci (S. mitis, S. constellatus and two S. intermedius strains) and Actinomyces (A. georgiae, and A. sp. oral clone) by 16S rDNA sequence homology. Recognition by affinity-isolated antibodies of antigens from the captured organisms was confirmed by Western analysis. Conversely, absorption of affinity-isolated antibodies with bacterial species specifically reduced subsequent recognition of epithelial antigens. To identify the auto-antigens, a human keratinocyte cDNA expression library in Lambda phage was probed using a pooled sera. Groups of responders were detected for CD24 (a recently described adhesion molecule also known as P-selectin ligand), antioxidant protein 2 (a newly recognised member of the thiol-dependment anti-oxidant proteins), lavtate dehydrogenase A, the transcription factor NFAT5, and for three genes encoding novel proteins. Six identified bacteria, especially S intermedius were demonstrated to absorb antibodies reaching with identified auto-antigens in patterns varying between individuals. This evidence indicated that during the course of periodontits, subjects develop increased levels of antibodies to common oral bacteria amongst which are included tissue cross-reactive antigens. Periodontitis could therefore present a risk for the subsequent initiation or exacerbation of a broad spectrum of disease processes including autoimmune, inflammatory, proliferative and degenerative disorders.

Thesis (Ph.D.) OGI School of Science & Engineering at OHSU, March 2008. / Includes bibliographical references (leaves 105 - 114).

Diss. (sammanfattning) Stockholm : Karol. inst., 2003. / Härtill 5 uppsatser.

Thesis (M. Med. Sc.)--University of Hong Kong, 2007.

Thesis (M.D.S.)--University of Adelaide, Dental School, 2001. / Includes bibliographical references (leaves 68-76).

Thesis (M.P.H.M.)--Mahidol University, 1999.

Thesis (M.S.)--University of Michigan, 1978.