THE BINDING OF DELMOPINOL AND CHLORHEXIDINE TO STREPTOCOCCUS-MUTANS AND ACTINOBACILLUS-ACTINOMYCETEMCOMITANS STRAINS WITH VARYING DEGREES OF SURFACE HYDROPHOBICITY

This study evaluated the binding of chlorhexidine and the new surface- active anti-plaque agent delmopinol hydrochloride to Streptococcus mut ans and Actinobacillus actinomycetemcomitans cells with various cell s urface hydrophobicities. The influence of saliva concentration on the binding of these compounds was also investigated. The radiolabeled com pounds were incubated with bacteria and the cells were recovered using a centrifugal filtering technique. Delmopinol had higher binding to t he hydrophilic variant strains than to the hydrophobic parent strains; chlorhexidine had higher binding to hydrophobic than to hydrophilic A . actinomycetemcomitans strains and higher binding to hydrophilic than to hydrophobic S. mutans strains. The presence of salivary films decr eased the binding of both compounds. Both delmopinol and chlorhexidine had stronger affinity to A. actinomycetemcomitans cells than to S. mu tans cells. At equimolar concentrations, delmopinol had a lower bindin g to all strains tested than chlorhexidine. The high reversibility of the delmopinol binding might be related to a higher diffusion rate and solubility compared with that of chlorhexidine. The amphiphilicity of both molecules is an important feature in their retention to S. mutan s and A. actinomycetemcomitans strains of varying hydrophobicities and could play an important role in the substantivity of delmopinol or ch lorhexidine in the oral cavity.