• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.2
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• pp.180-189
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• 2004

Chlorhexidine dihydrochloride and sodium fluoride have been used as agents inhibiting the replication of oral bacteria and the formation of dental plaque. There are various kinds of bacteria with different sensitivity against these agents. In this study, chlorhexidine dihydrochloride and sodium fluoride were studied about their effects on the replication of Streptococcus mutars, Streptococcus sobrinus, Streptococcus oralis and Streptococcus salivarius at their concentrations inhibiting the formation of artificial plaque by Streptococcus mutars. When Streptococcus mutans was cultured for 8 hours in the media added with $1.0{\mu}M$ chlorhexidine dihydrochloride, the weight of formed artificial plaque was decreased to $5.1{\pm}1.5mg$ compared with $106.1{\pm}18.1mg$ of the control(p<0.05). At the same time, the optical density of cultured media was decreased. The optical density of cultured media was slightly decreased in Streptococcus sobrinus, but was not decreased in Streptococcus oralis. The optical density of Streptococcus salivarius was decreased at 8 hours-incubation, was not decreased at 24 hours-incubation. When Streptococcus mutars was cultured for 8 hours in the media added with 3.0 mM sodium fluoride, the weight of formed artificial plaque was decreased to $26.7{\pm}8.3mg(p<0.05)$. At the same time, the optical density of cultured media was decreased. The optical density of cultured media was decreased in Streptococcus sobrinus and Streptococcus oralis, but was slightly decreased in Streptococcus salivarius. These results suggest that at the concentration of chlorhexidine dihydrochloride and sodium fluoridehe inhibiting the formation of artificial plaque by Streptococcus mutans, different species of genus Streptococcus show the different sensitivity against these agents.