[Plaque--gingivitis--periodontitis. (2) Microbiology and pathogenesis of periodontitis].

In a survey, current conceptions regarding the origin of gingivitis and periodontitis, as well as their clinical picture, are described. After the build-up of the bacterial plaque in several phases to form a periodontal pathogenic plaque, following a short, acute stage, a chronic gingivitis soon establishes itself in the neighbouring soft gingival tissue, from which, not inevitably, however, a periodontitis can develop after some years, the osseous parts now also being involved in the periodontal destruction, in which the polymorphonuclear neutrophilic granulocytes appear to have a major share. Depending on the age of the patient, progress of the disease, and the composition of the subgingival plaque, endeavours are made to classify the periodontal diseases into four subgroups. In recent years, however, doubt has increased as to whether gingivitis and even the periodontitides can be considered as comprising a single disease. However, this does not affect therapeutic concepts developed on the basis of opinions to date and which, as a rule, are successful, so that, for the time being, there is no reason for a change in this sphere.