Definition Saliva is a fluid secreted by salivary glands. Pure saliva is the secretion - PowerPoint Presentation

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Definition

Saliva is a fluid secreted by salivary glands. Pure saliva is the secretion of the major and minor salivary glands; saliva also called whole saliva, mixed saliva or oral fluid.

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Oral fluid consisted of:

1. Pure secretions of salivary glands (major and minor glands).

2. Gingival exudates.

3. Food debris.

4. Desquamated epithelial cells .

5. Microorganisms.6. Neutrophil and leukocytes, from gingival crevice or tonsils.7. Mucus secretion.

9. Acids (from GIT).I0. Co2 (from lung).11. O2 (from air).12

. Tears (from eye).

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COMPOSITION

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Saliva is made up of approx. 99% of water.

Organic components

Protein

200mg/100ml.

enzymes,immunoglobulins,mucins,traces

of albumin and polypeptides and glycopeptides.

-amylase{Ptyalin}

60-120 mg/100 ml in parotid.

25 mg/100ml in submandibular.

Immunoglobulins

Ig

A

Ig

G

Ig

M

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Anti bacterial substances

Lysosyme

Lactoferrin

Sialoperoxidase

Glycoproteins

Proline

rich glycoprotein seen in parotid saliva.

Other compounds

Siatherin

Sialin

Free amino acids

Urea

Glucose

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Inorganic constituents

Sodium

Potassium

Chloride

Bicarbonate

Calcium

Phosphorus

Flouride

Thiocyanate

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Factors affecting the composition of saliva include

:

Flow rate, Glandular source, Duration of stimulation, Previous stimulation, Nature of stimulation, Plasma composition (diet), Hormones, Pregnancy, Exercise, Genetic effects, Drugs, Various diseases and Age.

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Physiology of salivary gland

MECHANISM OF SALIVARY SECRETION

Basic

types of acinar epithelial cells exist:

- serous

cells, which secrete a watery fluid, essentially devoid of mucus

- mucous cells, which produce a very mucus-rich secretion

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Formation of the

acinar fluid

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CLASSIFICATION

1.Based on anatomic location

Parotid gland

Sub mandibular glandSub lingual glandAccessory glands (labial, lingual, palatal

buccal,glossopalatine

and

retromolar)2. Based on size and amount of secretion

Major salivary glands Minor salivary glands

 

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3. Based on type of secretion

Serous

Mucous Mixed

Parotid glands - Purely serous

Submandibular-Predominantly serous, Mixed

Sublingual - Predominantly mucous , Mixed

Labial,Buccal,Lingual{Ant.}- Mucous , Mixed

Palatine,Glossopalatine - Purely mucous.Posterior part of the tongue - Purely mucous

Von

Ebner’s

Glands - Purely serous

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Salivary production and oral clearance

Salivary flow (SF) index is a parameter allowing stimulated and unstimulated saliva flow to classified as normal, low, or very low (

hyposalivation). A healthy person’s mean daily saliva production ranges from (1 to 1.5 L). In adults, normal

total stimulated SF

ranges from 1 to 3 mL/ min, low ranges from 0.7 to 1.0 mL/min, while

hyposalivation is characterized by a SF of less than 0.7 mL/min. The normal unstimulated SF ranges from 0.25 to 0.35 mL/min, low ranges from 0.1 to 0.25 mL/min, while

hyposalivation characterized by a SF of less than 0.1 mL/ min. However, the values denominated “normal” for stimulated and unstimulated SF exhibit a large biological variation.

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( Oral clearance

).

residual volume

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Factors affection salivary flow rate:

Important:

Degree of hydration, Body position, Exposure to light, Olfaction (smell), Biological rhythms (Circadian rhythms, Cirannual

rhythms), Drugs

Unimportant

Gender, Body weight, Gland size

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Xerostomia

a Greek word where

xero mean dry while stoma mean mouth.

Causes of

Xerostomia

: (pathological conditions);1.

Sjogren syndrome, diabetes mellitus.2. Therapeutic radiation.3. Surgical removal of salivary gland.

4. Congenital absence of salivary gland.

5. Stone in the duct.

6. Malformation of salivary gland.

7. Acute viral infection, anxiety, mental stress, depression.

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Functions of saliva

1. Digestive function

The presence of salivary amylase helps begin the process of digestion of starch breakdown in the oral cavity.

Glycoproteins in the saliva helps to facilitate mastication, bind masticated food into a bolus aiding swallowing, and protects the soft

muscosal

surface from damage by coarse foods.Saliva acts a solvent to dissolve food substances thus allowing taste.

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2.

Inhibition of Dental Caries

immunological function e.g. secretory IgAenzymatic function via presence of

perioxidase

, lysozyme

mechanical function of cleaning the tooth surfacemaintenance of supersaturation with respect to hydroxyapatite

protective remineralization of carious lesion via ionic action e.g. fluoride, calcium

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3.Buffer

System in the Saliva

The salivary bicarbonate/carbonate buffer system responsible for rapid neutralization of acids produced by the metabolism of microbes in the oral cavity.

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4.Formation of Dental Pellicle

Saliva

protects the tooth surface against wear by creating a film of salivary

mucins and

proline

-rich glycoprotein, forming the dental pellicle.

The early pellicle proteins, proline-rich proteins (PRP) and statherin

, promote remineralization of the enamel by attracting calcium ions. demineralization is retarded by the pellicle proteins in concert with calcium and phosphate ions in saliva and in the plaque fluid.

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5.Antibacterial, Anti-microbial, Anti-fungal Function of Salivary Proteins

Secretory IgA prevents the adherence of oral microorganisms to the enamel pellicle via agglutination.

Perioxidase

inhibits acid production and growth of many oral microbes and fungi.

Salivary Lysozyme assists in the

lysis of bacteria in conjunction with other antibacterial systems.

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6. Prevention

of Halitosis and Cleansing of the Oral Cavity

Increased water in the saliva and salivary flow reduces halitosis by diluting and eliminating organic constituents of saliva producing methyl

mercaptan

and H

2

S.Agglutinated bacteria, food debris and oral epithelial cells are loosened by saliva and subsequently swallowed.

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Other functions

Protective: provides lubrication of soft oral tissues preventing abrasion during mastication, speech etc.

Speech facilitation