SALIVA (Composition and Functions) BY. Dr. Shahzadi Tayyaba Hashmi DNT 353

SALIVA Saliva is a complex secretion 93 % by volume is secreted by the major salivary glands and remaining 7 % is secreted by minor salivary glands 99 % of saliva is water and other 1 % is composed of organic and inorganic molecules Saliva plays an important role in maintaining the integrity of oral structures, in personal relationships, in the digestion and in controlling oral infections

MAJOR SALIVARY GLANDS 1)Submandibular salivary glands 2)Sublingual salivary glands 3)Parotid salivary glands

Minor salivary glands

COMPOSITION OF SALIVA Major components of saliva are : 1)Mucus serves as a lubricant 2)Amylase initiates the digestion of starch 3)Lingual lipase begins digestion of fat 4)Electrolyte solution ( Na+, Cl-,K+,HCO3-) moistens food 5) Proteins and enzymes : statherins, Proline-rich proteins, histatins, lysozymes, salivary peroxidase  Antimicrobial action  Lubrication  Buffer capacity and remineralization

FUNCTIONS OF SALIVA Lubrication Antimicrobial action Maintaining mucosa integrity Cleansing Buffer capacity and remineralization Preparing food for swallowing Digestion Taste phonation

Components and Functions of Saliva

FUNCTIONS OF SALIVA FUNCTIONS OF SALIVA

Functions of Saliva related to Dental Caries The part that saliva plays in protecting against caries can be summarized under four aspects: 1.Diluting and eliminating sugars and other substances 2.Buffer capacity 3.Balancing between demineralization and remineralization 4.Antimicrobial action

1) Dilution and elimination of sugars and other substances One of the important function of saliva is to remove microorganisms and dietary components from the mouth Studies have established that following the ingestion of carbohydrates, the concentration of sugars in saliva rises very quickly and then more slowly After ingesting sugars, the mouth contain a small volume of saliva, around 0.8 ml. The sugar is diluted in this small quantity of saliva. This stimulates the secretory response of the salivary glands, causing an increase in flow which can reach 1.1ml. when the food is swallowed, some sugar remains in the mouth and is diluted by saliva being secreted

1) Dilution and elimination of sugars and other substances High volume of saliva at rest increase the speed of sugar removal Elimination of sugars occurs faster in areas that are closest to the places where salivary gland ducts drain into the mouth Speed of clearance is slow on the retentive surfaces of teeth and more difficult for saliva to reach that surfaces There is the correlation between pH changes in the plaque and sugar clearance from the saliva. These changes are expressed by Stephen's curve

2) Buffer capacity Saliva contains specific buffer mechanisms such as bicarbonates, phosphate and some protein systems The carbonic acid-bicarbonate buffer acts above all when the stimulated salivary flow rate rises The phosphate buffer plays an essential role when salivary flow is low Certain proteins such as histatins or sialin are important for controlling the pH of saliva Buffer mechanisms occur faster on the surfaces of teeth which are covered by thin layer of plaque, than on the interproximal surfaces

3) Balance between Demineralization and Remineralization Caries lesions are characterized by a sub- surface demineralization of the enamel that is covered by a fairly well mineralized layer The factors that regulate the hydroxyapatite balance are the pH and the concentration of free calcium, phosphate and fluoride ions Both the saliva and plaque are supersaturated with calcium, phosphate and fluoride ions

3) Balance between Demineralization and Remineralization The caries process begins when bacteria ferment carbohydrates, resulting in the production of acids that lowers the pH of saliva and plaque and demineralization starts In the dynamic balance of caries process, supersaturation of saliva provides a barrier to demineralization and tips the balance towards remineralization Presence of fluorides assists this balance

Process of Demineralization Process of Demineralization Process of Remineralization Process of Remineralization

4) Antimicrobial Action Saliva maintains an important role in maintaining the equilibrium of the oral ecosystems and this is essential for dental caries control Saliva is able to perform antimicrobial action because it contains certain proteins Most important proteins involved in oral ecosystem maintenance are proline-rich proteins, lysozymes, lactoferin, as well as secretory immunoglobulin A and immunoglobulins G and M