Shear rate dependent viscoelastic behavior of human glandular salivas

Rheological properties of unstimulated human whole saliva (CHWS) and human glandular salivas (parotid, submandibular, sublingual, and palatal) of 7 healthy persons were investigated. The viscosity eta' and elasticity eta" of these salivas were measured as a function of oscillating shear rate gamma on an oscillating capillary viscoelasticity analyzer (Vilastic 3). Viscosity eta' and elasticity eta" of total and glandular salivas decreased in the following order: SL > Pal approximately CHWS approximately SM > Par. Rheological behavior of submandibular, palatal and sublingual saliva displayed a comparable pattern, although sublingual saliva showed significantly higher absolute values. The difference in viscoelasticity between submandibular and sublingual saliva was not due to differences in mucin concentration between SM and SL saliva. Flow curves of a range of SL saliva dilutions and flow curves of concentrated SM saliva showed that sublingual saliva was intrinsically more elastic than submandibular saliva.