Dry mouth — a review of this common oral problem

It is recognised that saliva is fundamentally important for the maintenance of oral and general health (Amerongen and Veerman, 2002; Napeñas et al, 2009).

Saliva primarily consists of water, ions and proteins that are secreted by salivary glands (Proctor and Carpenter, 2007). Moreover, saliva also mixes with other components found in the oral cavity, such as gingival crevicular fluid and microorganisms (Mese and Matsuo, 2007). In humans, saliva is always hypotonic when compared with plasma, whereby sodium and chloride ion concentrations are less than those found in circulating blood plasma (Porter et al, 2004). In addition to water, the ions and minerals excreted in saliva include: calcium, phosphate, bicarbonate, magnesium and zinc (Amerongen and Veerman, 2002). These substances play important roles in oral health and function — protecting teeth from harmful dietary and plaque-related acids, and enabling the tasting and eating of food (Table 1). In addition, proteins released in saliva include: mucins, enzymes and immunoglobulins (Amerongen and Veerman, 2002), which help with oral lubrication, eating, digestion and protection against infection (Table 1).