The effects of chlorhexidine gel on Streptococcus mutans infection in 10-month-old infants: a longitudinal, placebo-controlled, double-blind trial.

PURPOSE This study investigated the long-term effects of 0.2% chlorhexidine gel, used as a weekly brush-on gel, on Streptoccocus mutans infection in 10-month-old infants. METHODS The investigation followed the criteria of a placebo-controlled, double-blind, longitudinal clinical trial. Infants were recruited at birth and oral microbiological swabs were taken at 3 monthly intervals, together with medical, dental, dietary and brushing histories. Children who were found to be colonized with S. mutans were randomly assigned to either the chlorhexidine-gel group (N = 50) or placebo gel group (N = 46), and parents were instructed to brush the gel on the teeth once per week for 12 weeks. In another control group (N = 210), infants did not use either chlorhexidine or placebo gels. Saliva samples were cultured using S. mutans-selective tryptone-yeast extract-cysteine-sucrose-bacitracin (TYCSB) agar. The mean age of the children was 10.2 +/- 2.6 months at the start of the trial and subjects were followed until the ages of 18 months. RESULTS In the children with initial low S. mutans counts of < 300 CFU/mL, there was a significant percentage reduction in S. mutans counts in the chlorhexidine-gel group compared to the placebo gel and no-gel control groups after 3 months of weekly gel brushing. However, no significant differences with the placebo group were observed after 15 months of follow-up. There were 39 children (41%) who achieved reduction of their S. mutans to 0 CFU/mL. Compared to those who remained infected with S. mutans, these children had higher toothbrushing frequencies (P < .001) and toothpaste use (P < .001), as well as lower frequencies of daily feeds (P < .01), and lesser weekly frequencies of sweet solids and liquids (P < .001). CONCLUSIONS Children with relatively low initial S. mutans counts (< 300 CFU/mL) showed a reduction in S. mutans counts in the first 3 months when 0.2% chlorhexidine gel was brushed on the teeth weekly. No differences were observed when compared with the placebo and no-treatment groups at later follow-up periods.