Lubrication and viscosity features of human saliva and commercially available saliva substitutes

The lubricating features and viscosity of human saliva and five commercially available saliva substitutes were compared. The results indicate that little correlation exists between these parameters. Saliva substitutes based on carboxymethylcellulose do not appear to lubricate biocompatible hard interfaces well and, therefore, might not protect against the rapid attrition observed in xerostomic individuals. In contrast, a mucin-based substitute proved to be a better lubricant with values comparable to whole human saliva.