Chlorhexidine and Fluoride Varnishes Effects on Streptococcus mutans and Lactobacilli

Objective: To investigate the antibacterial effect of different dental varnishes on stimulated salivary Streptococci mutans and lactobacilli in children with rampant caries. Methods: Eighty five schoolchildren, aged 3-4 years, with at least two carious lesions involving dentine on the buccal surface of the upper anterior teeth, were randomly divided into five groups. Children in four groups were treated with Cervitec (1% chlorhexidine+1% thymol), Duraphat (5% NaF), Shellac-F (a locally produced varnish containing 5% NaF) and the mixture of Cervitec-Shellac-F (1:1 by volume). Varnish was applied once a week for two weeks onto all the tooth surfaces. CRT kit (Vivadent) and a 4-level scale was applied for bacterial evaluation. Bacterial levels were recorded at baseline, 7 and 30 days post-treatment. Toothbrushes and toothpaste were supplied and the children were instructed to maintain usual oral hygiene measures. The fifth group acted as a control and did not receive any treatment for the duration of the study. Results: The distribution percentage of subjects according to the four levels of S. mutans and lactobacilli showed no significant differences between groups at each time of bacterial evaluation (Kruskal-Wallis test, p>0.05). Significant difference in the level of S. mutans was seen in the group treated with the mixture of Cervitec-Shellac-F (Friedman test, p=0.012). This level was significantly decreased between day 0 and day 7 (Wilcoxon Signed Ranks test, p=0.016). The distribution percentages of subjects according to the four levels of S. mutans (in increasing order) in this group at baseline were 0, 0, 6.3, 93.8 and at day 7 were 6.3, 25, 18.7, 50. Conclusions: In children with rampant caries, all the varnishes failed to show any antibacterial effect on lactobacilli, meanwhile some reduction in the colonization of salivary S. mutans was obtained with the mixture of chlorhexidine and fluoride varnish.