Practical method to facilitate estimation of Streptococcus mutans levels in saliva.

A method was developed to facilitate the estimation of Streptococcus mutans levels in saliva. Saliva-contaminated wodden spatulas were pressed directly against an elevated agar plate containing a selective medium. The results were compared with the number of S. mutans per 1 ml of paraffin-stimulated saliva. It was shown that the spatula method gave a good estimation of the level of S. mutans infection. The incubation was also made in expired air instead of 95% N2-5% CO2. The outgrowth was in good agreement with that after conventional incubation. The method is useful in epidemiological studies or in selecting persons at a high caries risk, and when ordinary saliva sampling cannot be done, for example in small children. Compared with conventional saliva sampling, this method requires less time and material at sampling as well as at the laboratory.