Association of Streptococcus mutants with human dental decay.

The association of Streptococcus mutans with human dental decay was investigated by using several types of samples: (i) paraffin-stimulated saliva samples taken from children with from 0 to 15 decayed teeth; (ii) pooled occlusal and approximal plaque taken from children with no decayed or filled teeth, or from children with rampant caries of 10 or more teeth; (iii) plaque removed from single occlusal fissures that were either carious or noncarious. The results showed a significant association between plaque levels of S. mutans and caries. The strongest association, P < 0.0001, was found when plaque was removed from single occlusal fissures. Seventy-one percent of the carious fissures had S. mutans accounting for more than 10% of the viable flora, whereas 70% of the fissures that were caries free had no detectable S. mutans. Sixty-five percent of the pooled plaque samples from the children with rampant caries had S. mutans accounting for more than 10% of the viable flora, whereas 40% of the pooled samples from children that were caries free had no detectable S. mutans. Saliva samples tended to have low levels of S. mutans and were equivocal in demonstrating a relationship between S. mutans and caries.