Application of an antimicrobial varnish to the teeth of 33 adult volunteers resulted in the elimination of detectable mutans streptococci from the saliva of 21 of them for a mean period of 34.6 weeks (range, 4 to 89 weeks) without additional treatment. The mean number of applications of varnish required for elimination was 3.14 (range, 1 to 5). Extensive examination of 10 subjects made free of mutans streptococci on the basis of saliva examination revealed no detectable mutans streptococci in their dental plaque. In 14 of the subjects in whom mutans streptococci were eliminated, they subsequently re-appeared after a mean period of 22.7 weeks (range, 4 to 71 weeks). Four out of the five recurrences that were treated were eliminated with only one additional varnish application. The treatment failed to provide long-term elimination of detectable mutans streptococci in 12 of the 33 treated subjects. No serious adverse reactions were observed in any of the treated subjects. The results indicate that it is possible to eliminate mutans streptococci from man in a safe and effective manner.

An abbreviated treatment with a chlorhexidine-containing varnish was compared with a similar treatment with a placebo varnish and with a prophylaxis alone for its effects on the numbers of detectable salivary mutants streptococci in 51 adults. The varnishes, applied once weekly for four weeks, were held in place with a covering layer of either of two polyurethane sealants (FluorProtector or Adhesit). On the first appointment, the varnish-sealant combination was applied to all tooth surfaces, but on succeeding appointments only the occlusal and approximal surfaces were covered. The chlorhexidine varnish, covered with either sealant, reduced the salivary mutans streptococci by an average of 3 logs (99.9%) in all of the 20 subjects treated, and below detectable levels for at least four weeks in nine of them. In the groups receiving placebo varnish-sealant combinations, the mean log number of mutans streptococci of the subjects was reduced only by approximately 0.5 log (32%), and none of the subjects experienced loss of their detectable mutans streptococci for four weeks, although one subject did so for three weeks. No significant difference between the effects of the two polyurethane sealants was observed. Treatment with a single prophylaxis had no effect on mutans streptococcus levels. Subjects treated with chlorhexidine varnish also experienced an increase in S. sanguis and a small decrease in yeasts. Loss of detectable mutans streptococci did not cause changes in the numbers of other micro-organisms examined, beyond those observed with chlorhexidine varnish treatment alone.

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Isolates of mutans streptococci were obtained from the dental plaque of ten subjects before and after the subjects had been free of detectable mutans streptococci for a mean period of 14.6 weeks (range, from two to 36 weeks). The mutans streptococci had been rendered undetectable by chlorhexidine varnish treatment. Examination of the restriction endonuclease analysis (REA) patterns of the isolates revealed that all ten subjects had one strain (REA type) after re-appearance of the mutans streptococci that was identical to one that had been present before the varnish treatment. In six of the ten subjects, only one strain was detected both before and after treatment. Each of the other four subjects appeared to gain a new strain after treatment; one of the four appeared to lose one strain, and another, four strains. The ability of strains to persist after the period of undetectability seemed unrelated to their resistance to chlorhexidine or to their ability to exhibit insoluble glucan-mediated adhesion. In the subjects harboring multiple REA types, one-seventh of the tooth surfaces sampled harbored two strains simultaneously, suggesting an inability of either strain to exclude the other aggressively. Overall, the study indicated that every subject receiving chlorhexidine varnish therapy had a primary strain of mutans streptococcus that re-emerged after treatment. In contrast, secondary strains were highly susceptible to being lost or gained.

A chlorhexidine dental varnish was applied to the teeth of 26 children, ten to 17 years of age, in an attempt to limit the increase in colonization by mutans streptococci that normally accompanies the placement of fixed orthodontic appliances and to assess the acceptance of the application procedure. Despite the insertion of the appliances in the month following the varnish application, the numbers of detectable salivary mutans streptococci in the children were found to remain significantly lower than baseline values for seven months (p less than 0.01). Among the 26 children, 16 exhibited high counts (greater than 2.5 x 10(5) cfu/mL saliva) at baseline, but none exhibited such counts until three months post-treatment, when one child did. By seven months, eight children had high counts. No significant difference in effectiveness was observed between varnish formulations containing 10% or 20% chlorhexidine acetate, or between children of different ages or past caries experience. The lack of drop-outs and the results of a questionnaire indicated that acceptance of the treatment by the children was excellent. The study indicates that chlorhexidine varnish therapy was acceptable to the children and was effective in suppressing oral mutans streptococcal levels for long periods, even when used prior to the placement of fixed orthodontic appliances.