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Transcript of Saliva nitika jain
SALIVA
Dr. Nitika Jain
04/08/2023 SALIVA 2
contents
• Introduction• Salivary gland anatomy• Secretion of saliva• Composition of saliva
– Organic components– Inorganic components
• Functions of saliva
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What is saliva
• Saliva serves multiple and important functions. Three major, paired salivary glands produce the majority of saliva: the parotid, the submandibular, and the sublingual glands. In addition, 600-1,000 minor salivary glands line the oral cavity and oropharynx, contributing a small portion of total salivary production.
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Major salivary glands
• Parotid• Sub – mandibular• Sub - lingual
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Salivary gland - secretion
• Serous: very thin and wateryo parotid glando lingual glands of von Ebner
(serous glands of von Ebner)
Serous acini
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• Mucous: very thick and viscouso palatine glandso posterior lingual glandso labial buccal glands
Mucous acini
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• Mixed secretions: mix of the twoo Sublingual glands
– Mostly mucous with some serouso Submandibular glands
– Mostly serous with some mucouso Anterior lingual glands
– Mixed secretion
Mixed: mostly serous acini (dark), partially mucous acini (light
cells)
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Parotid gland
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Parotid gland
• Largest of all the salivary glands• Purely serous gland which
produces thin, watery, amylase rich saliva
• Superficial portion lies in front of the external ear and deeper portion lies behind the ramus of the mandible
• Stensons duct– Open out adjacent to maxillary
second molar
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• It is 5.8 cm in the craniocaudal dimension, and 3.4 cm in the ventral-dorsal dimension.
• Weight is 14.28 g. It is irregular, wedge shaped, and unilobular.
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• Superior border – Zygoma • Posterior border – External
Auditory Canal • Inferior border – Styloid Process,
Styloid Process musculature, Internal Carotid Artery, Jugular Veins
• Anterior border – a diagonal line drawn from the Zygomatic to external auditory canal.
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• Stensen’s duct arises from the anterior border of the Parotid and parallels the Zygomatic arch, 1.5 cm inferior to the inferior margin of the arch. Stensen’s duct runs superficial to the masseter muscle, then turns medially 90 degrees to pierce the Buccinator muscle at the level of the second maxillary molar where it opens onto the oral cavity.
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Sub – mandibular gland
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Sub – mandibular gland
• Second largest salivary gland• Produces 65-70% of total saliva
output• The duct is called Wharton’s duct• Wharton’s duct exits on the floor of
the mouth opposing the lingual surface of the tongue
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• Located in a depression on the lingual side of the mandibular body
• Innervated by parasympathetic nerve endings and possesses NO sympathetic receptors
• The parasympathetic fibers arrive through the facial and glossopharyngeal nerves
• Mixed secretion – mostly serous
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Sub – lingual gland
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Sub – lingual gland
– Smallest of the major glands– Produce less than 5% of total saliva
output• Saliva delivered via the ducts of Bartholin • The Bartholin ducts exit on the base of
the lingual surface of the tongue– Innervated by parasympathetic fibers – Little or no sympathetic influence – Mixed secretion – mostly mucous
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Minor salivary glands
• Minor salivary glands are found throughout the mouth: – Lips– Buccal mucosa (cheeks)– Alveolar mucosa (palate)– Tongue dorsum and ventrum – Floor of the mouth
• Together, they play a large role in salivary production.
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Histology of salivary gland
• The acini are the primary secretory organs but the saliva is modified as it passes through the intercalated, striated, and excretory ducts before being discharged into the mouth and oropharynx.
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• The serous cells contain numerous proteinaceous secretory (zymogen) granules. These granules contain high levels of amylase. In addition, the secretory cells produce kallikrein,lactoferrin, and lysozyme.
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Saliva
• General characterstics:Consistency - slightly cloudy due to
presence of mucins and cells Reaction - usually slightly acidic
(pH 6.02-7.05).On standing or boiling, it loses Co2 and becomes alkaline.
Specific gravity - 1.002-1.012 Freezing point - 0.07-0.34° Celsius
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• Percentage contribution of different salivary glands during unstimulated saliva:
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Unstimulated flow
• resting salivary flow―no external stimuluso Typically 0.2 mL – 0.3 mL per minuteo Less than 0.1 mL per minute means
the person has hyposalivation
Hyposalivation – not producing enough saliva
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Stimulated Flow
• response to a stimulus, usually taste, chewing, or medication eg, at mealtimeo Typically 1.5 mL – 2 mL per minuteo Less than 0.7 mL per minute is
considered hyposalivation
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The average person produces approximately 0.5 L – 1.5 L per day
• Salivary flow peaks in the afternoon
• Salivary flow decreases at night.• There is a difference in the quality
between stimulated and unstimulated saliva
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Ions and salivary flow
As saliva passes through the salivary ducts, cations (sodium and chloride)are reabsorbed into the adjacentblood vessels.
As saliva passes through the salivary ducts, cations (sodium and chloride) are reabsorbed into the adjacent blood vessels. In exchange, bicarbonates and potassium are transferred from the blood
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Stimulated Salivary Flow• Saliva passes through the salivary duct very rapidly o It impedes the exchange of sodium and chloride for
potassium and bicarbonate
Unstimulated Salivary Flow• Has a high content of potassium and bicarbonate oThe quality of unstimulated saliva will change when
flow increases because of a stimulus (chewing gum, thinking about lemons, looking at a food you crave)
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composition
• Water content - 99.5%• Solids - 0.5%
Inorganic content - 0.2% Organic content - 0.3% Gases - 1ml
oxygen/100ml - 2.5ml
nitrogen/100ml - 50ml
carbondioxide/100ml Cellular elements
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Organic Components of Saliva
Enzymes:• Amylase – converting starch into
glucose and fructose • Lysozymes – prevents bacterial
infections in the mouth • Histatins – prevents fungal
infections • Secretory IgA – immunity mediator
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• Lactoperoxidases – stimulation of minor salivary glands
• RNase and Dnase – cellular maintenance
• Lipase – initiates digestion of fat • Kallikrein – vasoreactive
substances
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Cellular Composition
• The cellular composition consists of:
• Epithelial cells • Neutrophils • Lymphocytes • Bacterial flora
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-Amylase
• Present in parotid saliva at conc. of 60-120 mg/ 100ml in submandibular
saliva at approx. 25 mg/100 ml.
• Very little amylase activity in the sublingual and minor glandular secretions.
• 6 isoenzyme forms exist; alpha-amylase (ptyalin) is Ca++ dependent and
readily inactivated by a pH of 4 or less.
• The enzyme hydrolyses the alpha 1:4 glycosidic bond between glucose units
in the polysaccharide chain of starch.
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Lysozyme
• An antibacterial enzyme.
• The mean concentration in whole saliva
– resting: 22 mg/100ml.
– Stimulated: 11 mg/100 ml.
• Lysozyme acts on the B (1-4) bond between N-acetyl-muramic acid and N-
acetyl glucosamine in the Gram positive bacterial cell wall component.
• Lysozyme may also be bactericidal,
• Inhibits mucosal colonization by microbial aggregation.
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Kallikrein
•Splits serum beta-globulin into bradykinin
•Functional vasodilatation to supply an actively secreting gland.
Dextranases
Increased whole saliva dextranase levels may be associated with
impaired oral hygiene and over consumption of sucrose and
related fermentable carbohydrates which support the growth of
organisms producing dextranases.
Invertases
•High invertase activity is based on the involvement of several
enzymes chiefly derived from dental plaque S.Mitis and
S.Salivarius.
• High invertase activity ---- consume high sucrose and it usually
parallels with high lactobacillus and streptococcus counts of
plaque.
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Glycoprotein (Mucins)
• Lubricant
• Types—MG1 & MG2
• Polypeptide chain that stick together
• Low solubility, High viscosity, Strong
adhesiveness
• Aids in mastication, speech, swallowing by
lubrication
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Glycoprotein (Mucins)
• Preserve mucosal integrity
• Protective barrier against excessive wear
• Antibacterial action by selective adhesion of microbes to oral tissue surface
• Barrier against acid penetration
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MG1
• High molecular-wt
• Adsorbs tightly to tooth surface--
enamel pellicle formation--Protection
from acid challenges
• High in caries susceptible patients
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MG2
• Low molecular wt
• Binds to enamel but get displaces
easily
• Promotes the aggregation and
clearance of oral bacteria (S.mutans)
• High in caries resistant cases
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Secretory leucocyte proteinase inhibitor (SLPI)
Proteinase inhibitory property
Antimicrobial and antiviral
Imp. Role in wound healing
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Tissue inhibitors of metalloproteinase
Remodeling of extracellular matrix in
inflammation
Growth promoting activity
Stimulation of osteoclastic bone resorption
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Immunoglobulins
• Secretory IgA is the predominant immunoglobulin - 20mg/100ml
• 90% of the total parotid lgA
• 85% of whole saliva lgA
• 30-35% of which is derived from minor glands, IgG (1.5 mg/100ml) & IgM (0.2 mg/100ml)
• Secretory IgA is synthesized by plasma cells within the glands in addition to the mucosal
epithelial cells.
• Secretory IgA --- non-lymphoid-derived glycoprotein designated as the secretory
component.
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Immunoglobulins
• This IgA exhibits 3 possible functions:
-Inhibition of bacterial colonization, probably by
agglutination.
- Binding to specific bacterial antigens involved with
adherence.
-Affecting specific enzymes essential for bacterial
metabolism.
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Structural features of salivary proteins
• Proline – rich proteins
• Statherins
• Cystatins
• Histatins
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Proline-rich protein (Glycoprotein)
70% of total secretory proteins
Acidic (Large), Basic (Small)
Present in enamel pellicle
Larger PRP promote bacterial attachment
Smaller reduces the initial bacterial attachment
A.Viscosus, S.mutans, S.Gordoni
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Statherin (Phosphoprotein)
• Is a small phosphoprotien (12000 daltons) relatively
rich in tyrosine and proline which has the property of
inhibiting Hydroxyapatite crystal growth.
• Potential precursor of enamel pellicle
• Inhibit spontaneous precipitation of cal.
phosphate in saturated solution
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Cystatins
• Several cystatins are
phosphorylated and bind to HA
• Inhibit crystal growth of Cal.
Phosphate salts
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Histatin
• Parotid and Submandibular saliva
• Bind to HA, precursor of acquired pellicle
• kills C.Albican in yeast form and mycelia form
• Bacteriostatic
• Inhibit hem agglutination and thereby
colonization
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Other organic compounds
Free Amino acids- (Below 0.1 mg/100 ml)o Too low to provide nutrient source
for bacterial growth Urea (12-20 mg /100 ml)
o Hydrolyzed by bacteria with the release of Ammonia---Rise in pH
Glucose (0.5- 1 mg/ 100ml)o Too low for bacterial growtho Increase in DM
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Lipids
Cholesterol, fatty acid
glycerides,
phospholipids
Corticosteroids
Cortisol and cortisine
1-2 mg/100ml
Vitamins
Water soluble vitamins5304/08/2023 SALIVA
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Function of saliva
Protective properties:– Lubrication – Maintenance of mucous membrane
integrity– Soft tissue repair– Dilution and clearance– Aggregation– Action of lactoferrin– Salivary peroxidase system– Antifungal activity
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Function of saliva
– Antiviral activity
– Buffering capacity of saliva
– Maintenance of tooth integrity
• Digestion
• Taste
• Saturation
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Lubrication
• Coat the food, the oral soft and hard tissues.
• Allows food to travel through the digestive system surfaces with
minimal friction.
• Without appropriate lubrication, food is retained and impacted
around the teeth,
• Both mg1 and mg2 can provide fluid layers with high-film strength
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Maintenance of mucous membrane integrity
Salivary mucins possess rheological properties that include
low solubility, high viscosity, elasticity, and adhesiveness.
Provide an effective barrier against desiccation and
environmental factors
Protect the underlying cells from sudden changes in osmotic
pressure.
Second line of defense against protease activity-cysteine
containing phosphoprotien
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Soft tissue repair
• EGF involved in oral wound healing
• Hormone like properties in stimulating
epithelial cells
• Parotid gland is the major source
• VEGF also known as vasculotropin---- an
angiogenic cytokine
• PAF ---- a potent phospholipid mediator
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Dilution and clearance
Saliva dilutes and eliminates dietary sugars
and acids
This process is dependent on flow rate and
swallowing frequency
Oral sugar clearance extensively prolonged
when unstimulated whole saliva flow rate is
below .2ml/min
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Aggregation Inhibit bacterial attachment
Inhibits the adherence of these cariogenic organisms to teeth
and protection against caries.
Clumping of bacteria
Hinder effective adherence
Expectorated or swallowed
Histidine-rich peptide has growth-
inhibitory and bactericidal effects on oral
bacteria.
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Action of lactoferrin
• Lactoferrin, the exocrine gland secretion
• The bacteriostatic properties are attributed to the ability of the
unsaturated protein to bind two iron atoms per molecule
• Lactoferrin is capable of both a bacteriostatic and a bactericidal
effect on S mutans that is distinct from simple iron deprivation.
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Action of salivary peroxidase
• The antimicrobial effect of salivary peroxidase against S mutans is
significantly enhanced by interaction with secretory lgA.
• Interaction with each other and with high molecular weight mucin.
This mucin serve to concentrate a defense force on the mucosa
against the external environment, entrapping and incapacitating
microorganisms.
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Antifungal activity
• Parotid fluid has an antifungal capacity, reflecting properties
of both the neutral and the basic histidine rich peptides.
• Pollock and others showed that the basic peptides could
cause 99% loss of viability of Candida albicans at levels of
25 mg/ml,
• Oppenheim and others found that the neutral histidine rich
peptide was a potent inhibitor of C. albicans germination at
levels as low as 2 mg/ml.
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Antiviral activity
• Antibodies (secretory lgA) can directly neutralize viruses.
• Mucins are also effective antiviral molecules.
• A major function of saliva is to prevent the establishment of
unwanted species in the first place
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Buffering capacity Resistance to pH changes at an arbitrary point.
3 buffer systems :
o Carbonic acid / bicarbonate
o Phosphate
o Protein
o CO2 + H2O H2CO3 H+ + HCO3-
o Concentration of bicarbonates is highest in parotid saliva
CA CA
pH
Secretion rate
Buffer capaci
ty
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Maintenance of tooth integrity
• Physical flow of saliva (the hydrokinetic property) coupled
with muscular activity,
• Small decrease in the resting salivary flow rate can greatly
prolong sugar clearance time.
• Interaction with saliva provides a post eruptive maturation
through the diffusion of ions
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• This enrichment of the crystal structure increases hardness,
decreases permeability, increases resistance to caries.
• The original pellicle is replaced by a constantly replenished
salivary film selectively absorbed proteins with a
high affinity for hydroxyapatite provides a protective
barrier
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Digestion
SALIVARY AMYLASE
STARCH DIGESTION
STARCH CLEARANCE
LIBERATING MALTOSE
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Saliva is formed in 2 stages :
• A primary secretion
occurs in the acini
• Then modified as it passes through the ducts
Mechanism of saliva formation
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METHOD OF COLLECTING SALIVA
Passive drool
Oral swab
Infant swab
Spitting method
Suction method
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• • Avoid alcohol for 12 hours before sample collection.
• • Avoid eating major meal within 60 minutes of sample collection.
• • Avoid dairy products for 20 minutes before sample collection.
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• Avoid foods with high sugar or acidity, or high caffeine content, immediately before sample collection, since they may compromise the assay by lowering saliva pH and increasing bacterial growth.
• • Rinse mouth with water to remove food residue before sample collection. Wait at least 10 minutes after rinsing before collecting saliva to avoid sample dilution.
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Prior to saliva collection
• Participants should rinse with water 10 minutes prior to collection.
• Cut plastic drinking straws into 2-inch (5 cm) pieces.
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PASSIVE DROOL
• Passive drool is highly recommended because it is cost effective and approved for use with almost all analytes. To avoid problems with analyte retention or the introduction of contaminants, use only high quality polypropylene vials for collection, such as our 2 ml cryovials. The vials used must seal tightly and be able to withstand temperatures as low as -80ºC.
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Instructions to the patient
• Allow saliva to pool in the mouth.• With head tilted forward,
participants should drool down the straw and collect saliva in the cryovial. (It is normal for saliva to foam, advise using a vial with twice the capacity of the desired sample volume.)
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• Repeat as often as necessary until sufficient sample is collected. One mL (excluding foam) is adequate for most tests. Collection of samples to be analyzed for multiple analytes may require larger vials.
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Salimetrics Oral Swab (SOS)
• Participants who are not willing or able to drool saliva into a vial.
If the saliva samples are to be analyzed for cortisol, testosterone, α-amylase, chromogranin A, cotinine, C-reactive protein, or SIgA, the Oral Swab is an excellent alternative to passive drool because of its ease of use. The SOS also helps filter mucus from the sample, help improve immunoassay results.
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Children and infant swab
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To be continued…
• Saliva as a diagnostic marker• Diseases• Xerostomia• Conclusion