[Proportion and frequency of 3 kinds of anaerobic bacteria in relation to the gingival index].

The proportion and frequency of three groups of particular bacteria (Bacteroides, Fusobacterium and spirochetes) were studied in relation to the gingival index on the sites from which they were sampled. Seventy eight samples collected from 40 individuals were studied together with measurements of the gingival index and the pocket or sulcus depth. The samples were dispersed by ultrasonic treatment, diluted and cultured on a non-selective medium. The identification of the species was done by biochemical tests and by analysis of the metabolic products with gas chromatography. As a whole, our results support the hypothesis of an important change in the microbial flora from a clinical healthy status (with predominant Gram positive facultative anaerobic bacteria) to disease (with predominant Gram negative strict anaerobic bacteria). Furthermore the results suggest that Bacteroides gingvalis as well as Fusobacterium nucleatum and spirochetes through their high frequency and important proportion at the affected sites played an etiological role in the pathogenesis of gingivitis and periodontis Man.