Effect of chlorhexidine and iodine on the composition of the human dental plaque flora.

Localized areas of the dentition in human volunteers were treated once with chlorhexidine or iodine. Plaque samples taken from the experimental surfaces were analyzed for the number of Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus and the total viable counts. Chlorhexidine and iodine strongly suppressed S. mutans and A. viscosus, but S. sanguis was much less affected. A. viscosus returned to its original level within 7 days after chemotherapy. S. mutans returned much slower to its pretreatment level. In fissures and restoration margins, S. mutans was still significantly suppressed 21 days after chlorhexidine application.