What Is Periodontal Disease

The anatomical region where the tooth meets the gum (or gingiva) is particularly interesting as it is a junction between hard and soft tissue (Figs. 7.1a, b), where a nonshedding tooth surface may be colonised with dental plaque in close proximity to the supporting periodontal tissues. Within dental plaque, the pathogenic organisms and the various virulence factors they release, stimulate a reaction by the hosts' inflammatory and immune systems, indeed, a delicate equilibrium exists

School of Dentistry, The University of Manchester, Higher Cambridge Street,

Manchester M15 6FH, UK

e-mail: [email protected]

M. Lyte and P.P.E. Freestone (eds.), Microbial Endocrinology, Interkingdom Signaling in Infectious Disease and Health,

DOI 10.1007/978-1-4419-5576-0_6, © Springer Science+Business Media, LLC 2010

a Gross Regional Anatomy

Enamel

Dentine Pulp

Periodontal Ligament

Gingival Crevice

Gingiva (Gum)

Bone

Gingival Crevice

Gingiva (Gum)

Bone

Periodontal Health

Periodontal Health

Periodontal Disease

Fig. 7.1 (a) Gross regional anatomy. (b) Healthy periodontal tissues. (c) Periodontal disease b c between the host and plaque microorganisms and changes in either component may result in periodontal tissue destruction (Fig. 7.1c).

The composition of dental plaque is highly complex and diverse containing bacteria imbedded in a polymer matrix derived from bacteria and saliva (Marsh and Martin, 1999). These components form a biofilm on the tooth surface within which are found areas of high and low bacterial populations. It is likely that the bacterial components of the plaque biofilm are able to communicate with one another as a prerequisite for the continued development of an ordered multi-species community observed in the plaque biofilm (Kolenbrander et al. 2002). This communication includes the receptors for mucins, agglutinins and alpha-amylases and the adhesins used for coaggregation and co-adherence between bacterial species, which are important in establishing the arrangement of organisms within the biofilm. The bacteria within the dental plaque biofilm in periodontal disease are primarily obligate anaerobes or capnophilic Gram-negative organisms, which represent a shift from the microflora within dental plaque from healthy subjects or those with gingivitis, which are primarily Streptococci and Actinomyces species.

The importance of Gram-negative bacterial species in the pathogenesis of perio-dontitis and in the production of autoinducers by organisms found within the gastrointestinal tract sparked the research effort into the microbial endocrinology of dental plaque.

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