Saliva in health and disease, chemical biology of

Saliva is a bodily fluid secreted by three pairs of major salivary glands (parotid submandibular and sublingual) and by many of minor salivary glands. Saliva is supplemented with several constituents that originate from blood serum, from intact or destroyed mucosal and immune cells, and from intact or destroyed oral microorganisms that result in a complex mixture of a variety of molecules. Saliva plays an important role in acquired pellicle formation on tooth surfaces, crystal growth homeostasis, bacterial adhesion, plaque formation, and—because of its lubricating effect—in maintaining mucosal integrity of the oral and upper gastrointestinal mucosal surfaces. It also plays an important role in physico-chemical defense, antimicrobial defense, and wound healing. Many saliva constituents including proteins, carbohydrates, lipids, and ions interact under fine regulation to fulfill these important tasks. Local and systemic disorders may disturb and interrupt these complex balanced functions, which can lead to mucosal and tooth damages. In other cases, systemic disorders induce salivary changes without any significant local effects. Many such changes are of high diagnostic interest because they can be rather specific to the causing conditions and can be used for screening and early diagnosis of several local and systemic disorders.