Salivary counts of mutans streptococci and lactobacilli in children ageing 6-8 year old having a socioeconomic background in Brazil.

Saliva samples from students aged 6 to 8 year-old were analysed in order to determine the incidence of Streptococcus group mutans and Lactobacillus. Two hundred children were examined, distributed in five socioeconomic categories (A to E). Stimulated saliva samples were collected and inoculated into the SB20 and Rogsa agar culture medium for the Streptococcus and Lactobacillus cultivation. After growth, the number of these microorganisms (CUF/mL) was determined after identification of the representative colonies by biochemical methods on the basis of carbohydrate fermentation. A significative part of the population, particularly among the lower socioeconomic categories (D/E) was considered a high risk group in developing dental caries because of the high number of Streptococcus group mutans and Lactobacillus.