In vitro interactions of delmopinol hydrochloride with salivary films adsorbed at solid/liquid interfaces

Delmopinol hydrochloride is a highly surface active substance which has been shown to reduce the amount of plaque in vitro and in vivo and the level of gingivitis in vivo. Ellipsometry was used to evaluate the effect of delmopinol on films formed from whole, parotid and sublingual/submandibular saliva on solid surfaces. Hydrophilic plasma cleaned silica and methylated hydrophobic substrates were used. The adsorption processes of the salivary proteins and their interactions with delmopinol were monitored in situ with a Rudolph thin-film ellipsometer. The adsorption of delmopinol on bare substrates with out previous salivary adsorption was also investigated and the results indicate that delmopinol molecules were adsorbed on both hydrophilic and hydrophobic surfaces. When delmopinol interacted with the films formed from the different types of saliva an initial increase in the adsorbed amounts was observed in the majority of the cases indicating binding to the salivary pellicles and/or substrate surface. The noted increases were largest for the films adsorbed from whole and sublingual/submandibular saliva. After rinsing in the system, partial desorption of the salivary films took place. It is thus indicated that delmopinol binds to salivary proteins within the pellicles and alters the cohesive and adhesive properties of these films.