Microbial Coaggregation in the Oral Cavity

Abstract

Gingivitis and periodontitis are the most common human diseases with bacterial etiology. Almost all adults worldwide experience gingivitis and some degree of periodontitis. Gingivitis can persist for prolonged periods without significant progression or can serve as a precursor to periodontitis in susceptible individuals. Periodontitis lesions are virtually irreversible and exhibit destruction of the connective tissue attachment, apical migration of the junctional epithelium and resorption of the adjacent alveolar bone. Clinically, it results in deep periodontal pockets, exposure of the root cementum to the oral environment, and eventual loss of dentition. The natural occurrence of initiation and subsequent progression of periodontal disease has been followed in a homogeneous population in Sri Lanka over a 20 year period (Loe, 1986). This study has shown that in the complete absence of oral hygiene and oral health care, all participants exhibited visible plaque, gingivitis and supra- and subgingival calculus in all teeth. But despite the remarkable homogeneity of the group, the severity of the disease among individuals varied greatly. On the basis of the rate of periodontal attachment loss, this population could be divided into three groups: (i) those who showed rapidly progressing periodontitis (approximately 8%), (ii) those who showed moderately progressing periodontitis (80%), and (iii) a small but significant group who exhibited no progression of the disease beyond chronic gingivitis. It is the observation of this last group which challenges the understanding of the mechanism(s) of how and what turns on the progression of the periodontal lesion, and how it is turned off. This is still unresolved.