Saliva is a vital body fluid, without it, continued healthy functioning of the oral cavity would not be possible. The multiple functions of saliva relate both to its fluid characteristics and specific components. As a fluid, saliva facilitates mastication, bolus formation, swallowing, lubrication of the mucosa and speech. Specific components of saliva contribute to antimicrobial activity, buffering actions, digestion and the protection and maintenance of mucous membrane.
Its major components, water and mucin, serve as a cleansing solvent and lubricating fluid. In addition it contains digestive enzymes: lingual lipase and ptyalin (salivary amylase), mucins, and electrolytes (sodium, potassium, chloride). It maintains the normal antimicrobial factors, epidermal growth factor, minerals and buffering systems. It maintains normal balance of the oral flora, protecting mucosa from overgrowth of potentially pathogenic organisms, most notably Candida species. The viscosity of saliva is much higher than that of plain water due to the presence of various glycoproteins and immunoglobulins. These and other chemical characteristics give saliva its coating and lubricating properties.