Effectiveness of chlorhexidine varnish for preventing caries uncertain

Medline, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), and reference lists of reviews.

Randomised or quasi-randomised controlled trials with blind outcome assessment and a minimum duration of 1 year comparing chlorhexidine varnish to placebo, no treatment or fluoride varnish were included. Split-mouth trials were included but analysed separately. The primary outcome measure was the caries increment determined using the decayed missing and filled surface (DMFS/dmfs) index. Only trials where caries were assessed by visual/visual-tactile or radiographic methods were included.

Data were extracted by one author and verified by a second. It was planned to present the results graphically in a forest plot and formally assess statistical heterogeneity. However, due to missing data and variation in the reporting of outcomes, this was not possible. Consequently a narrative summary of the results is presented with parallel-group and split-mouth trials considered separately. Heterogeneity was assessed informally.

12 trials were included (eight parallel group, four split-mouth trials) There was considerable variation between trials in the concentration and frequency of application of the chlorhexidine varnish, in baseline caries levels and in background exposure to fluoride. Six parallel group trials reported no statistically significant difference in caries increment in permanent teeth with the application of chlorhexidine varnish compared to placebo or no treatment. The results of 4 split-mouth trials were conflicting: 2 trials found no significant difference in caries increment and 2 reported statistically significant results in favour of chlorhexidine varnish. One trial of the effect of chlorhexidine varnish in primary teeth demonstrated a statistically significant reduction in caries increment. The results of 1 trial comparing chlorhexidine varnish with fluoride varnish for preventing caries in adolescents were equivocal.

Evidence regarding the effectiveness of chlorhexidine varnish for preventing caries is inconclusive. Further well-conducted randomised trials are required before chlorhexidine varnish can be recommended for caries prevention.