Lubrication.

Saliva is capable of decreasing friction force by at least 2 orders of magnitude when in between hydrophobic surfaces. This ability to lubricate is key to oral health, food processing and taste perception. In this paper different mechanisms of saliva lubrication are reviewed, and their interconnection is demonstrated using a simple physical framework. The current understanding of the roles of the molecular structure and physicochemical properties of major salivary proteins and protein complexes on lubrication is summarised and critically evaluated.