Adsorption of chlorhexidine and black tea onto in vitro salivary pellicles, as studied by ellipsometry

Abstract

The adsorption from 0.2% (w/w) chlorhexidine and black tea solutions onto an in vitro pellicle from whole unstimulated saliva on hydroxyapatite discs was studied by ellipsometry. It was found that chlorhexidine adsorbed to the pellicle causing a modification of the pellicle properties, leading to a subsequent increase in adsorption of salivary and black tea components. There was a distinct order of addition effect, whereby chlorhexidine followed by black tea gave an overall greater adsorption of components compared to black tea followed by chlorhexidine. This increase in adsorption gave a concomitant increase in colour or stain as measured by a reflectance chromameter. The increase in adsorbed amounts and stain was modified in part by the adsorption of salivary fractions between the chlorhexidine and black tea treatments. In all cases, the chlorhexidine and black tea modified pellicles were not readily removed by either phosphate or sodium dodecyl sulphate rinses. Thus, following chlorhexidine exposure, the accelerated adsorption of salivary and black tea components can ultimately lead to increased staining of the pellicle.