CARIOGENICITY DEPENDS MORE ON DIET THAN THE PREVAILING MUTANS STREPTOCOCCAL SPECIES

This review aims to compare the occurrence and distribution of mutans streptococci in Africa, Europe, and North America and in addition will try to offer explanations for existing relationships among salivary m utans streptococci counts, dietary patterns, and dental caries. The li terature reveals that salivary mutans streptococci counts in child pop ulations of the three continents are comparable. The distribution of m utans streptococci species, with a predominance of S. mutans followed by S. sobrinus, and the virtual absence of other mutans streptococci s pecies are also comparable. Although it is widely believed that diet h as an important effect on mutans streptococci counts, this review prov ides evidence that this does not hold true when variations in dietary patterns are moderate, as they normally are in real-life situations. S ince the diets of the child populations in the three continents vary m oderately, a strong dietary-induced effect on salivary mutans streptoc occi counts cannot be expected. The observed analogous salivary mutans streptococci counts in these child populations are thus 'not surprisi ng' but are in accordance with the conceptual expectation. The differe nces in caries experience in children of the three continents cannot b e explained by the prevailing mutans streptococci species but instead should be attributed to differences in the cariogenicity of the variou s diets. The fact that the cariogenicity of the diet determines the de velopment of dental caries while hardly affecting the mutans streptoco cci counts explains the limited value of the latter as an indicator of dental caries. The reviewed literature shows that mutans streptococci are ubiquitous in children aged 7 years and older in Africa, Europe, and North America. Mutans streptococci should therefore be considered as belonging to the indigenous microflora of the human mouth.