Efficacy of a chlorhexidine and a chlorhexidine-fluoride varnish mixture to decrease interdental levels of mutans streptococci

The aim of the present study was to evaluate and compare the efficacy of a chlorhexidine/thymol-containing (CHX) and a chlorhexidine/thymol/fluoride-containing (CHX + F) varnish to decrease interdental levels of mutans streptococci (MS). Eighty-two healthy schoolchildren (11-13 years) with high scores of salivary MS were selected by a screening procedure and randomised into two groups. MS were enumerated at all mesial interdental sites of the first permanent molars with the aid of a modified chair-side technique. The interdental molar and premolar sites were treated with either a 1% CHX varnish (Cervitec) or a 1:1 mixture of the CHX varnish and a fluoride varnish containing 0.1% w/w difluorsilane (Fluor Protector; CHX + F) on two occasions within a 2-week period. The varnishes were applied with a small brush after cleaning with dental floss and drying with air. Follow-up samples from the interdental areas were collected after 1 and 3 months. Both groups exhibited a similar statistically significant (p < 0.05) reduction of interdental MS after 1 month when compared with baseline. After 3 months, a significant reduction (p < 0.05) was still found in the CHX + F varnish group but not in the CHX varnish group. In conclusion, the results suggest that the addition of fluoride to an antibacterial varnish might improve the long-term efficacy in diminishing the cariogenic microbial challenge. Thus, the mixed varnish concept should be further developed and warrants an implementation of clinical studies.