SALIVARY MUTANS STREPTOCOCCI AND CARIES PREVALENCE IN 8-YEAR-OLD SWEDISH SCHOOLCHILDREN

The aim of this study was to obtain cross-sectional information about the quantitative distribution of salivary mutans streptococci assessed with a clinically applicable microbiological method and the relation to dental caries in young schoolchildren. A total of 355 8-year-old children were examined for the presence and number of mutans streptococci in saliva by a specially prepared strip, the "Strip-mutans" method, cultivated in a selective broth. The strips were first visually examined and grouped by aid of a templet provided by the manufacturer and thereafter transferred to a laboratory for enumeration of colony forming units (CFU) with aid of a stereomicroscope. Caries scores were obtained from the dental records. Mutans streptococci were identified in 70% of all children. 46% were free from the bacterium or harboured low levels (0-10 CFU) while high levels (greater-than-or-equal-to 500 CFU) were found only in 6% of the material. Strong positive correlations (p < 0.001) were found between different levels of mutans streptococci infection and the caries experience in both the primary (dmfs) and the permanent (DMFS) dentition. A statistically significant correlation between the direct examination and the microscopic enumeration was disclosed (r = 0.84). The bacterial culturing technique used in this study proved to be practical and reliable and thus useful in clinical routines of pediatric dentistry.