Antimicrobial effects of the combination of chlorhexidine and xylitol.
To assess the effect of combining 1% chlorhexidine varnish (CHX) with xylitol chewing gum (XYL) on Streptococcus mutans and biofilm levels in 6-8-year-old children. Randomised controlled study. Eighty-two 6-8-year-old children were randomly divided into groups as follows: G1 (n = 20): xylitol chewing gum twice a day after breakfast and lunch; G2 (n = 20): xylitol gum as G1 plus chlorhexidine varnish application at the start of the study and after one and two months; G3 (n = 20): chlorhexidine varnish as G2; and G4 (n = 22): fluoride gel application at the start of the study and after one and two months. Microbiological tests were performed to assess Streptococcus mutans colony forming units (CFU) and the teeth of those children with moderate or higher CFU scores were examined for visible biofilm. CFU scores were categorised as follows: 0 = absence of S. mutans, 1 = low level (1-10 CFU), 2 = moderate level (11-100 CFU), 3 = high level (101-250 CFU), 4 = very high level (>250 CFU). Biofilm scores based on a scale from 0 (absence of biofilm) to 5 (thick biofilm firmly adhered to posterior and anterior teeth) were obtained. The biofilm reduction was greater in G2 and G3, with mean values of 3.38 and 3.17 to 1.79 and 1.88, respectively (p <0.05). All groups presented a reduction in the S. mutans levels. XYL + CHX showed the largest reduction throughout the study period, with 58.3% in the first month, 84.2% in the second and 92.9% at the end of the study. The XYL + CHX combination was efficient and superior to single treatments in controlling biofilm and suppressing S. mutans.