The saliva is a mixture of secretions of the salivary gland and gingival fluid exudates. It is slightly alkaline and consists of water and 0.58% solids. Saliva has many functions. It serves as protection for it is a lubricant. Its glycoprotein content protects the lining mucosa by forming a barrier against noxious stimuli, microbial toxins, and minor trauma. Its fluid caonsistency provides a mechanical washing action, which flushes away nonadherent bacteria and acellular debris from the mouth. In particular, the clearance of sugars from the mouth limits their availability to acidogenic plaque microorganisms. The calcium-binding proteins in saliva help form a salivary pellicle, which behaves as a protective membrane.Second, the buffering capacity of saliva prevents pathogens from colonizing in the mouth by denying them optimal enviromental living and reproducing conditions. The ability of saliva to buffer acid prevents demineralization of the enamel, and also is very important because saliva and plaque pH are generally lower in caries-active individuals.
Also, a salivary pellicle, called a "sialin", raises the pH of the dental plaque after exposure to fermentable carbohydrates. Next, saliva aides in digestion. Saliva provides taste acuity, neutralizes esophageal contents, dilutes gastric chyme, forms the food bolus, and because of its amylase content, breaks down starch. Finally, saliva enhances taste by breaking down food molecules into a solution that is then brought into contact with the tastebuds.