1. (COMPOSITION AND FUNCTION Dr. Shahzadi Tayyaba Hashmi
SALIVA
(COMPOSITION AND FUNCTION
Dr. Shahzadi Tayyaba Hashmi

2. 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

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

4. Minor salivary glands

5. COMPOSITION OF SALIVA Major components of saliva are :
Mucus serves as a lubricant
Amylase initiates the digestion of starch
Lingual lipase begins digestion of fat
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

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

7. Components and Functions of Saliva

8. FUNCTIONS OF SALIVA RELATED TO DENTAL CARIES
The part that saliva plays in protecting against caries can be summarized under four aspects:
Diluting and eliminating sugars and other substances
Buffer capacity
Balancing between demineralization and remineralization
Antimicrobial action

9. 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

10. 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

11. 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

12. 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

13. 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

15. Process of
Demineralization
Process of
Remineralization

16. 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

17. Thank you