Can the Colonisation Resistance of the Oral Microflora be Enhanced?

INTRODUCTION The oral cavity offers a large number of shedding and non-shedding surfaces for colonisation. Initial colonisers tend to be aerobes or facultative anaerobes, relatively quick-growing, and able to adhere or be retained at a particular surface. Although many specific interactions are known between microorganisms and oral surfaces, there is an element of chance involved in which organisms initially colonise any particular site and thus fill the related niches in the ecosystem. These initial random events thereby determine the sequence of subsequent ecological succession.2 The oral cavity, in addition to its spatial heterogeneity, is subjected to temporal fluctuation^,^' e.g. in the rate of salivary flow, and in the host diet which varies in composition and frequency of intake. These characteristics of the oral cavity result in a large number of ecological niches, which may be physical, metabolic and temporal. Therefore, an extremely rich and complex commensal flora develops, primarily in surface-associated microbial films. Once the oral flora has become established, inter-relationships build up and the flora becomes synergistically integrated." Thus, homeostasis tends to restore the initial community when alien microorganisms are introduced. This is observed as the phenomenon known as colonisation resistance .