Inhibitory effect of a mouth rinse formulated with chlorhexidine gluconate, ethanol, and green tea extract against major oral bacterial species

Mouth rinses are a useful supplementary tool for the prevention of oral infectious diseases. Although the antimicrobial effects of mouth rinses have been investigated, there are few studies focusing on the comparison of the effects among various oral bacterial species. In the present study, the inhibitory effect of a commercial mouth rinse, “ConCoolF,” and each of its major components, chlorhexidine gluconate, ethanol, and green tea extract, on multiple species of oral bacteria were investigated. Inhibition of bacterial growth was observed in all cariogenic streptococcal species with different genera, serotypes, and strains isolated from different countries when either the complete mouth rinse or chlorhexidine gluconate were used. However, no growth inhibition was observed when the bacteria were exposed to ethanol or green tea extract. Interestingly, growth inhibition was greatly reduced in non-cariogenic streptococci compared with cariogenic streptococci. In addition, both the mouth rinse and chlorhexi-dine gluconate inhibited the biofilms formed by both Streptococcus mutans (S. mutans) and Porphyromonas gingivalis (P. gingivalis), among which the inhibitory effect against S. mutans was higher than that against P. gin-givalis. These results suggest that a mouth rinse containing chlorhexidine gluconate, ethanol, and green tea extract, or chlorhexidine gluconate alone, exhibits antimicrobial activity against several oral bacteria species, having greater activity against pathogenic bacteria.