Lessons Learned from Clinical Studies: Roles of Mutans Streptococci in the Pathogenesis of Dental Caries

Dental caries is a major health problem worldwide. This disease results from improper interactions between oral microorganisms and host that stimulate the establishment of cariogenic biofilms on tooth surfaces, whose high and sustained acidogenicity promotes demineralization of tooth tissues. These interactions are modulated by environmental factors, among which diet has significant impact, especially regarding its carbohydrate content. Although microorganisms are recognized as having a central role in dental caries, current approaches for intervening in the establishment of cariogenic biofilms are limited. In this review, we focus on clinical studies supporting the role of mutans streptococci (MS) as promoters of cariogenic microbiota. Functions of MS in this process are analyzed under the current knowledge about the genetic and phenotypic diversity of Streptococcus mutans, the most well-known MS species. Effects of host immune responses on the establishment and pathogenesis of S. mutans are also discussed, further encouraging studies testing anti-MS therapies.