Microbial etiology of periodontal disease.

Abstract

Abstract Longitudinal studies with humans indicate that gingivitis is associated with an increased dental plaque mass. Also, prior to the onset of gingivitis, changes in the microflora towards a more complex bacterial composition frequently occur. On the other hand, recent cross sectional cultural studies generally do not reveal clear‐cut differences between the composition of the subgingival microflora associated with healthy or inflamed gingivae. Also, some studies have demonstrated an enhanced cell‐mediated immune response during the course of gingivitis to a variety of subgingival plaque bacteria. It has also been observed that plaques allowed to form on cleaned teeth for 2 or 3 days do not differ substantially in their microbial composition. However, long‐term thorough oral hygiene performed at intervals of 48 h permits maintenance of gingival health, whereas that instituted at intervals of 72 h will lead eventually to gingivitis. Collectively, this evidence supports the concept that the etiology of gingivitis is bacteriologically nonspecific. Thus a large increase in the accumulation of bacteria on the tooth surface per se may have a greater pathogenic effect on the periodontal tissues than the relatively minor and inconsistent shifts in the microbial composition.The transition from gingivitis into periodontitis may be induced by changes in the pathogenic potential of subgingival plaque. Gram‐negative rods appear to be specifically associated with periodontitis. A growing body of evidence implicates especially Bacteriodes asaccharolyticus as one of the responsible pathogens.Juvenile periodontitis (periodontosis) seems to be a distinct disease entity. Recent findings suggest abnormalities in peripheral blood polymorphonuclear leucocytes (PMNL) of patients with juvenile periodontitis. The subgingival microflora is different from that associated with periodontitis and the findings so far implicate Actinobacillus actinomycetemcomitans as an important pathogen.The bacterial etiology of acute necrotizing ulcerative gingivitis (ANUG) is still unclear. Satisfactory cultural studies have yet to be performed. The presence of spirochetes in the ulcerative lesions of the junctional epithelium does not necessarily imply that they play an important role in this disease entity.Future research on the bacteriology of periodontal disease should concentrate on longitudinal studies; particular attention should be paid to the change of gingivitis into periodontitis whereby animals as well as humans can be used. Improvements of sampling methods as well as precise and simple identification techniques of microorganisms are required.