Spirochetes are putative periodontal pathogens because they are found in increased numbers in periodontitis. With severity of periodontal disease, there also appears to be an increase in oral malodor. This is due to a greater breakdown of tissues containing sulfurated amino acids such as cysteine, cystine, and methionine. Bacteria in the oral cavity can metabolize these amino acids to produce volatile sulfur compounds such as hydrogen sulfide and methyl mercaptan that contribute to oral malodor. Detection of volatile sulfur compounds is usually performed by gas chromatography or a portable sulfur monitor, but none of these methods provides direct evidence for the production of hydrogen sulfide from oral spirochetes. A successful method has been developed, as described in this thesis, to demonstrate that oral spirochetes are major contributors to oral malodor associated with periodontitis. This has been accomplished by modification of an established method for isolating these bacteria directly from subgingival plaques. / A morphological variation of spirochetes, called a spherical body, exists. It has been postulated that this may be a dormant form of spirochetes used as a survival strategy. A number of environmental conditions were tested to determine whether or not they could contribute to spherical body formation in the oral spirochete Treponema denticola ATCC 35405. Cells grown in the absence of rabbit serum, volatile fatty acids, thiamine pyrophosphate, or yeast extract showed a dramatic increase in the numbers of spherical bodies. T. denticola cells grown in the presence of the metabolic end-product lactic acid or at pH 7.42 instead of 6.8 also contained more spherical bodies than the control.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.27304 |
| Date | January 1997 |
| Creators | De Ciccio, Angela. |
| Contributors | Chan, E. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Faculty of Dentistry) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001565163, proquestno: MQ29679, Theses scanned by UMI/ProQuest. |
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