Effect of chlorhexidine gel treatment on Streptococcus mutans population in human saliva and dental plaque.

The effect of topical application of a 1% chlorhexidine gel on the population of S. mutans in dental plaque and saliva was studied in five subjects highly infected with the organism. After treatment for 5 min daily for 14 d, S. mutans was not detected in three of the subjects and counts of 700 colony-forming units or less per ml of saliva were found in the other subjects. Reappearance of S. mutans was slow and did not reach pretreatment level until 14 weeks or more after therapy. The proportion of S. sanguis in plaque increased temporarily after chlorhexidine treatment, whereas the population of lactobacilli was unaffected. These observations indicate that short-term use of chlorhexidine is of value in controlling oral infection of humans by S. mutans.