Saliva

Saliva is one of the defense mechanism systems of the gingiva. It is a clear, tasteless, odorless, viscous fluid, slightly acidic in nature with a ph of 6.8 consisting of secretions from the parotid gland, sublingual gland, submandibular gland, and mucous glands of the oral cavity. Saliva is the mechanical cleaner of the oral surfaces, by buffering acids produced by bacteria and controlling bacterial activity. Saliva is composed of 98% water, while the other 2% consists of other compounds such as electrolytes, mucus, antibacterial compounds, and various enzymes.

Functions Of Saliva #

• Lubrication and protection
• Buffering action and clearance
• Maintenance of tooth integrity
• Antibacterial and antifungal activity
• Taste and digestion
• Antibody- IgA
• Contains coagulation factors
• Exchange of calcium and phosphate ions
• Oral mucosa and esophagus protection

Lubrication and Protection #

As a seromucous coating, saliva lubricates and protects oral tissues. Mastication, speech, and swallowing all are aided by the lubricating effects of mucin. Mucins also perform an antibacterial function and as a part of the enamel pellicle, mucin help initiates bacterial colonization.

Buffering Action #

Saliva dilutes and removes substances (oral debris, noxious agents) from the oral cavity which is referred to as salivary or oral clearance. The salivary buffer bicarbonate-carbonic acid system maintains the physiological ph of the oral cavity. Saliva contains coagulation factors like factor -viii, ix, x, PTA, and hageman factor that hasten blood coagulation and protects the wound from bacterial invasion and colonization. Like bicarbonates, even phosphates help in preventing the oral cavity from bacterial invasion.

Maintenance Of Tooth Integrity #

Saliva facilitates the demineralization and remineralization process. Demineralization occurs when acids diffuse through plaque and the pellicle into the liquid phase of the enamel between crystal and enamel. Whenever the enamel layer gets damaged due to the acids released by the bacteria, the saliva tries to recover it by the process called remineralization. The fluorides, calcium, phosphates, and other minerals present in saliva will also help in maintaining the tooth’s overall health and thus maintaining the integrity of the tooth.

Antibacterial and antifungal activity #

Salivary glands are exocrine glands and as such, they secrete fluids containing immunologic and non-immunologic agents for the protection of teeth surfaces. Saliva contains lysozyme, lactoperoxidase, glucoprotein, mucin, myeloperoxidase, antibodies, etc. Lysozyme is a hydrolytic enzyme that cleavages linking beta1,4 -glycosidic bond of peptidoglycans of the bacterial cell wall. Myeloperoxidases released are bacteriocidal in nature.

Taste And Digestion #

Sense of taste is activated during the initial stage of ingestion of food particles. Saliva has an early, limited role in total digestion by beginning the breakdown of starch with amylase, a major component of parotid saliva that initially dissolves the sugar.

Antibodies IgA and IgG #

The most predominant antibody released by saliva is IgA which is derived from plasma cells in the salivary gland. It maintains the homeostasis in the oral cavity and helps in reducing the bacteria by stopping them from adhering to the oral structures and the teeth. Salivary IgG is derived from serum via GCF (gingival crevicular fluid) and is present in small amounts in the saliva. The number of IgG increases in cases of inflammation during gingival or periodontal problems causing an increased amount of GCF.

Composition Of Saliva #

• Inorganic -The inorganic composition of saliva includes the calcium, phosphate, fluorides, hydrocarbonates, thiocyanates, etc
• Organic - The organic components include mucin, lipase, amylase, SIgA, statherin, histatins, peroxidases, sugars, urea, amino acids, blood group substances, steroid hormones, proline-rich proteins, etc