Effect of single and repeated application of chlorhexidine varnish on mutans streptococci in plaque from fissures of premolar and molar teeth.

The aim of this study was to determine the effects of one and two applications of 40% chlorhexidine varnish on the numbers of mutants streptococci in human dental fissure plaques from molar and premolar teeth. Twenty-nine subjects (aged 20-30 years) participated in the study and were randomly assigned to one of three groups. In each subject two fissures with high levels of mutants streptococci were selected. The fissures in group 1 (control group) were treated with placebo varnish containing no chlorhexidine. Fissures in group 2 received a single application of 40% chlorhexidine varnish, whereas fissures in group 3 received an additional chlorhexidine varnish application 1 week after the first application. Fissure plaque samples were taken prior to the first application of chlorhexidine varnish and subsequently 1, 2, and 4 months thereafter. Compared with the fissures in the control group, the suppression of mutans streptococci was significant in plaques from group 2 for up to 2 months and in plaques from group 3 for up to 4 months after application. Mutans streptococci were suppressed more strongly in premolar than in molar teeth and more strongly and for a longer period of time in fissures of premolar teeth treated twice than in fissures of premolars treated once.