Dental bacterial plaques Nature and role in periodontal disease Lars A. Christersson, Joseph J, Zambon and Robert J. Genco Departments of Oral Biology and Periodontology, School of Dental Medicine, State University of New York at Buffalo, 3435 Main Street, Buffalo, N.Y 14214, USA Christersson LA, Zambon JJ and Genco RJ: Dental bacterial plaques. Nature and role in periodontal disease. J Clin Periodontol 1991; 18: 441—446. Abstract. Antony van Leeuwenhoek first described oral bacteria. However, not until almost 200 years later was the famous Koch postulate introduced. Since then, research has extensively been performed regarding the development and microbiology of dental plaques. In spite of the complexity of the developing flora of supragingival plaque, culture studies have shown a remarkably orderly suc- cession of organisms. Lately, the concept of microbial specificity in the etiology of periodontal diseases has been widely suggested, i.e., that different forms of periodontal disease are associated with qualitatively distinct dental plaques. Cross-sectional and longitudinal studies of the predominant cultivable micro- flora reveal that only a small number of the over 300 species found in human subgingival plaques are associated with periodontal disease. Among the com- monly mentioned are: Actinobacillus actinomycetemcomitans, Bacteroides gingival- is, Bacteroides intermedius, Capnocytophaga sp., Eikenella corrodens, Fusobacter- ium nucleatum, and Wolinella recta, as well as certain gram-positive bacteria such as Eubacterium species. Anti-infective therapy for many systemic infections equals the use of antimicrobial drugs. However, for localized infections like periodontal diseases, treatment may consist of a combination of mechanical wound debridement and the application of an antimicrobial agent. The general effective- ness of mechanical anti-infective therapy and successful oral hygiene in the management of periodontal disease is well established in the literature and has met the test of success in clinical practice for most cases of periodontitis in adults. The definition of periodontal pathogens as either opportunistic pathogens, or as exogenous pathogens carries with it significant implications. If periodontal disease results from an opportunistic infection by indigenous micro-organisms, then preventive efforts should be directed toward removing most plaque from all tooth surfaces. However, if periodontal diseases result from a subgingival infection with exogenous pathogens, appropriate preventive strategies may be used for control of oral colonization or subgingival growth. Key words: dental plaques; exogenous patho- gens; preventive strategies; specific perio- dontitis pathogens Accepted for publication 19 December 1990 Antony van Leeuwenhoek 1683, in a let- ter to the Royal Society in London, was the first one to describe oral bacteria (an- imacules) (Dobell 1960). He described his oral hygiene efforts, including the use of salt, and concluded that despite these, he could observe more living organisms in his oral cavity than human beings in his home country The Netherlands. He also made the observation that he had exceptionally good oral health, and that his gums did not bleed when cleaned. De- spite this remarkable accomplishment, it took almost 200 years until mankind 1 .'alized the relationship between bac- i.ria and disease when Koch (1876) i lowed that anthrax in cattle was caused 1 V a specific bacteria. His extensive re- 5 arch later led to the development of 1 och's postulate, i.e. that to claim bac- t rial specificity: (1) a bacteria should be able to be isolated from the diseased tissues; (2) pure cultures can be obtained; (3) that the bacteria when inoculated in experimental animals should cause the disease; (4) that the bacteria should be able to be isolated from the diseased tissues in the experimental animal. As early as 1890, Miller, one of Koch's pu- pils, made efforts to isolate the organism responsible for pyorrhea. The efforts, however, were unsuccessful, and Miller concluded that several organisms were responsible for this disease (Miller 1973) which is one of the first statements of what has become known as the non-spe- cific plaque hypothesis. According to this hypothesis, dental plaque is a homo- geneous bacterial mass causing peri- odontal disease when accumulating to the point of exceeding host defense ca- pacity. In contrast, Bass & Johns (1915) hy- pothesized that a specific micro-organ- ism, Endoameba buccalis, was the cause of periodontal disease and that a vaccine developed against this micro-organism could be used to prevent tooth loss. Ac- cording to one of the first suggestions of what is now called the specific plaque hy- pothesis, dental plaques from diseased sites are different from those adjacent to healthy sites and those in normal sub- jects. Nevertheless, bacteria-forming pla- ques on the teeth, either supragingivally or subgingivally, are the causative agents responsible for gingivitis and perio- dontitis (Loe & Silness 1963). Plaque control therefore, plays a central key role in the therapeutic arsenal directed toward these diseases, and it is important to understand the formation, develop-