Variables influencing Streptococcus mutans testing.

When saliva is sampled to estimate S. mutans, variables may influence the results. The purpose of the present study was to assess the reliability of the tongue depressor for saliva sampling, and whether the sampling time during the day influences S. mutans counts. The study population consisted of 27 children, between 24 and 66 months of age. Samples of unstimulated saliva were gathered on tongue blades four times during the day for each subject. Paired samples representing both sides of the tongue blades were inoculated onto elevated agar plates containing a selective medium, and anaerobically incubated at 37 degrees C for 48 hr. After examining 76 paired samples of saliva, no significant differences in S. mutans counts were found between sides of the spatula, suggesting that the sampling technique was suitable. Analysis of variance showed significant differences within each subject over the four sampling times (P less than .01). A significant difference was found between subjects' daily averages (P less than .05).