Predominant cultivable microflora of supragingival dental plaque in Chinese individuals

The aim of this study was to determine the predominant supragingival cultivable bacterial flora in Chinese individuals, using the experimental gingivitis model. A total of 11 healthy dental students, mean age 22.5 years (range 20-25) were recruited. All were provided with once-a-week dental prophylaxis and oral hygiene reinforcement for 3 weeks to ensure gingival health. In the fourth week, after prophylaxis, the participants entered a 14-day period without any plaque control. A plaque sample was collected at days 1, 3, 7 and 14 from the buccal surface of the upper right canine, second premolar, first premolar and first molar, respectively. Each sample was then dispensed in tryptic soy-broth transport medium and grown anaerobically to obtain pure cultures, which were subsequently identified. Results showed that Gram-positive cocci and rods were the predominant cultivatable species (51-61%) in the samples throughout the 14-day period; with time there was a decreasing percentage of cocci and an increasing percentage of rods. Gram-negative cocci and rods increased in proportion with the plaque age (11-37%). Streptococcus spp. were the predominant Gram-positive cocci while Actinomyces were the predominant Gram-positive rods isolated. Fusobacterium and Capnocytophaga spp. were the two most frequent Gram-negative anaerobic rods cultured. The results compared with those from other analogous studies from the West suggest the possibility of interracial differences in supragingival plaque flora.