Africa, Charlene W.J.2014-01-092014-01-092012Africa, C.W.J. (2012). The Microbial Aetiology of Periodontal Diseases. In J. Manakil, (ed). Periodontal Diseases - A Clinician's Guide. InTech, pp3-54978-953-307-818-2http://hdl.handle.net/10566/932Introduction: The study of the aetiology of periodontal diseases has continued for decades with much progress shown in the last two decades. Having moved through periods of “whole” plaque (with emphasis on mass) being attributed to the disease process, to “specific” species being implicated, we have finally returned to examining the oral microbiota as an ecological niche involving not only a selected few species but looking at plaque as a whole where all the players are invited to participate with their roles no longer individually defined but viewed as a team effort with recognition of their individual strengths and contributions. Recent findings using advanced technology, are confirming findings viewed by electron microscopy nearly half a century ago, but we now have the knowledge and expertise to interpret those findings with deeper understanding. This chapter will attempt to examine the microbial succession within the plaque biofilm from health to disease, bearing in mind the susceptibility of the host, the microbial heterogeneity and the expression of virulence by the putative pathogens.en© 2012 Africa; licensee InTech. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Periodontal diseasesBacteriaBook chapter