Chlorhexidine dihydrochloride와 불화나트륨은 구강 내 세균을 억제하고 치태의 형성을 억제하기 위하여 많이 사용되고 있는 물질이다. 그러나 구강에는 여러 종류의 세균들이 상주하며 이들 물질에 대한 감수성도 다르다. 본 연구에서는 chlorhexidine dihydrochloride와 불화나트륨에 의해 Streptococcus mutans의 인공치태 형성이 억제되었을 때 Streptococcus mutans, Streptococcus sobrinus, Streptococcus oralis, Streptococcus salivarius의 증식에 미치는 이들 물질의 영향을 관찰하여 다음과 같은 결과를 얻었다. Streptococcus mutans를 8시간 배양하면 와이어에 형성된 인공치태 무게는 $106.1{pm}18.1mg$이었으나, $1.0{mu}M$ chlorhexidine dihydrochloride를 첨가하면 $5.1{pm}1.5mg$으로 감소되었다(p<0.05). 이 때 배양액의 흡광도도 감소되었다. Streptococcus sobrinus의 배양액 흡광도는 약간 감소되었으나 Streptococcus oralis에서는 감소되지 않았고 Streptococcus salivarius에서는 배양 8시간에 감소되었다가 배양 24시간에 대조군과 차이가 없었다. 배지에 3.0mM 불화나트륨을 첨가하여 Streptococcus mutans를 8시간 배양하면 와이어에 형성된 인공치태 무게는 $26.7{pm}8.3mg$으로 감소되었다(p<0.05). 이 때 배양액의 흡광도도 감소되었다. Streptococcus sobrinus와 Streptococcus oralis에서의 배양액의 흡광도도 감소되었으나 Streptococcus salivarius에서는 거의 감소되지 않았다. 이상의 결과는 Streptococcus mutans의 인공치태 형성을 억제하는 chlorhexidine dihydrochloride와 불화나트륨 농도에서 Streptococcus의 여러 종의 감수성이 각각 다르다는 것을 시사하였다.
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.
