The Oral Spirochetes: Their Ecology and Role in the Pathogenesis of Periodontal Disease
Stanley C. Holt and Jeffrey L. Ebersole
from: Pathogenic Treponema: Molecular and Cellular Biology (Edited by: Justin D. Radolf and Sheila A. Lukehart). Caister Academic Press, U.K. (2006)
Abstract
Nearly 350 years ago Antoni van Leeuwenhoek described "living animalcules aswimming... The biggest sort bent their body into curves going forward...". Thus, the first written descriptions of what we now know to be spirochetes. These prokaryons are found both free-living in nature, and associated with a variety of animals, and humans. Both nonpathogenic and pathogenic species of spirochetes have been identified. Their participation as etiologic agents in human oral disease has been debated for many years. Numerous investigations have reported low numbers of spirochetes in the gingival sulcus at health sites, while disease progression with gingival inflammation, increased pocket depth, and a more anaerobic microenvironment correlated with an increase in the numbers and variety (small, medium, large) of spirochetes. Additionally, return to oral health resulted in the decease in the number of spirochetes to levels consistent with gingival health. Seminal contributions of Socransky and colleagues demonstrated that the microbial ecology in oral health and periodontitis was comprised of many individual genera and species; however, several specific microbial complexes or consortia appeared to reflect alterations in the clinical state of the site. In particular, one prominent consortium consists of P. gingivalis, T. forsythensis, and T. denticola. This chapter provides an overview of the characteristics of oral spirochetes, and particularly T. denticola as important members of oral biofilms and their relationship to periodontal disease. The content of the chapter also focuses on attempting to summarize the literature with regard to the numerous potential "virulence molecules" expressed by the spirochetes that might be essential for their in vivo survival and contribution to the progression of oral disease in susceptible hosts read more ...
