Advances in oral microbiology.

More than 200 species of micro-organisms have been identified in the resident oral microflora colonizing teeth and oral mucosa. Their numbers and proportions are regulated by several ecological mechanisms such as antimicrobial factors in saliva and gingival fluid, intermicrobial synergism and antagonism, host diet, etc. Due to their pathogenic potential, oral micro-organisms cause dental caries, periodontal disease, mixed anaerobic infections of oral tissues, and sometimes infections in other organs. The role of specific bacteria or virulence factors in plaque-induced diseases is difficult to assess because of the microbial complexity and variability of dental plaque. Correlations have been established between Streptococcus mutans, lactobacilli and dental caries, and also between spirochaetes, certain Gram-negative rods and periodontal inflammation. The predictive value of microbiological tests as indicators of active caries or periodontal destruction is, however, too low to justify clinical use. Preventive methods such as plaque control and sugar restriction help establish a microflora compatible with oral health.