Salivary Mutans Streptococci and Caries Experience in Primary Schoolchildren

Salivary levels of mutans streptococci in 104 3rd grade (8-year-old) and 94 6th grade (11-year-old) primary schoolchildren were determined by the “Strip mutans” test. The strip with adherent colonies was visually scored at four levels (classes 0-3), from low (class 0: 106 CFU/ml saliva) mutans counts (Jensen & Bratthall, 1989) according to the manufacturer's template. Caries status was examined by the criteria of WHO (WHO, 1987).We cross-sectionally analysed the possible relation between salivary levels of mutans streptococci and caries experience. The presence of mutans streptococci was demonstrated in 84% of 3rd grade and 73% of 6th grade schoolchildren and its proportional distribution with different levels of mutans streptococci was almost uniform. No statistical diference in the distribution was found between 3rd and 6th grade children.As mutans streptococcal levels increased, there was a trend toward increased caries experience in both 3rd and 6th grade children. In the 3rd grade, statistically higher dft (p<0.01) and DMFT (p<0.05) were found at a mutans streptococcal level of class 3 than at a lower concentration (class 0). This was probably due to the large number of untreated deciduous teeth. In the 6th grade, similar correlations were found between class 3 and class 0.These findings confirm that high numbers of mutans streptococci in saliva (class 3) indicate a high risk of caries.