The insoluble glucan is the major substance of dental plaque. In order to isolate the bacteria inhibiting the formation of insoluble glucan in disposable cuvette, saliva was got from about 10 thousand children. The isolated bacteria were tested by API 20S kit and API 50 CHL kit. These bactreia were identified as Streptococcus oralis, Streptococcus mitis, Streptococcus mitior, Streptococcus sanguis, Enterococcus durans, Lactococcus lactis, Lactobacillus acidophilus. When Streptococcus mutans was cultured with Streptococcus oralis, Streptococcus mitis, Streptococcus mitior, Streptococcus sanguis, Enterococcus durans, Lactococcus lactis, or Lactobacillus acidophilus in disposable cuvette, the optical density at 550 nm was 0.823, 0.912, 0.894, 0.878, 0.753, 0.845, 1.021 respectively, while being 1.503 in the disposable cuvette culturing Streptococcus mutans only.