Rheological properties of commercially available polysaccharides with potential use in saliva substitutes.

The rheological properties of a number of natural and synthetic polysaccharides have been compared with porcine gastric mucin (PGM), a mucin-containing saliva substitute (Saliva Orthana) and with clarified human whole saliva (CHWS). The effects of ionic strength, pH and calcium and fluoride ions on the viscoelastic properties of these polymers have been investigated. Of the polysaccharides tested, xanthan gum and scleroglucan appeared to resemble CHWS most in viscoelastic behavior and may be potential candidates for use in artificial saliva. Both PGM and Saliva Orthana, however, did not show any elastic behavior, whereas a viscosity comparable to human saliva was only observed in highly concentrated solutions. Of the polysaccharides tested, scleroglucan also had mucin-adhesive properties resulting in rheological synergism. This may be the first step in mucoadhesion which may protect underlying oral surfaces in vivo.