INTERACTIONS OF CHLORHEXIDINE WITH SALIVARY FILMS ADSORBED AT SOLID-LIQUID AND AIR LIQUID INTERFACES

Chlorhexidine is a cationic compound which has been shown to bind to s alivary proteins and enamel through electrostatic interactions. The ai ms of this study were to investigate the interaction of chlorhexidine molecules with salivary films adsorbed on solid surfaces with varying physico-chemical characteristics and to investigate the effect of diff erent concentrations of chlorhexidine on the surface tension of saliva . The interactions between 0.2% chlorhexidine digluconate with films a dsorbed from whole saliva were monitored by a Rudolph Thin-film ellips ometer equipped with a He-Ne laser (632.8 nm). The films were adsorbed on hydrophilic silica surfaces which were plasma cleaned or on methyl ated hydrophobic surfaces. Experiments of chlorhexidine adsorption on bare surfaces were also performed. The surface tension of mixtures of whole saliva with various concentrations of (0.1%, 0.2%, 1%) chlorhexi dine was monitored with a tensiometer. The results show that chlorhexi dine adsorbs on both types of studied substrates. Addition of the subs tance followed by rinsing caused a partial desorption of the adsorbed pellicles. Furthermore, at all studied concentrations chlorhexidine re duced the interfacial tension. There are indications that the amphiphi lic characteristics of the molecule play an important role in the rete ntion of the substance in the oral cavity.