Current understanding of the cause of dental caries.

Dental caries-associated oral streptococci are called the mutans streptococci, with Streptococcus mutans and Streptococcus sobrinus being the most prevalent caries-associated organisms in humans. Strains of the mutans streptococci are highly conserved within not only mothers and their children but also racial groups, suggesting vertical transmission of this organism within human populations. It has been found that the mother-child infection route of the mutans streptococci can be prevented by simply reducing the amount of the mutans streptococci contained in the mothers' saliva. Moreover, a chlorhexidine varnish reduces the salivary mutans streptococci by an average of 3 logs (99.9%), and moved them below detectable levels. We should attempt to eliminate the infection with the mutans streptococci among Japanese people by attempting to break the infectious chain from mothers to children.