Antiseptic activity of some antidental plaque chemicals on Streptococcus mutans biofilms

S. mutans is one of the bacterial species involved in the initiation of cariogenic dental plaque. In situ, antiseptic activity evaluation of dental plaque chemicals is fairly difficult. A dynamic biofilm model of S. mutans on Tygon support is suitable for the quantification of antiseptic activity and the comparison of commercial chemical formulations, submitted or not to the french standards and Pharmacopea. Some of these chemicals, especially quaternary ammonia solutions, do not reduce living bacteria counts by 10E5 as AFNOR specifies. In the case of dental plaque, antiseptic activity is probably not the only relevant parameter: biofilm dissociation is rather more relevant because the dead or living bacteria adhere to the teeth, favouring the establishment of a new active biofilm. Two proceedings can be followed: support surface can be modified, or bacteria exopolymers synthesis can be inhibited to prevent cell adherence; the disruption of the biofilm glycocalyx can be achieved with enzymes or surfactants.