Physiology of saliva

Physiology of Saliva
Presented by-
Dr. Jayesh Khandewal
Dept of Paedodontics and
Preventive Dentistry
20 January
2019
1

Contents
 Introduction
 Development of salivary glands
 Classification of salivary glands
 Anatomy of salivary glands
 Vascular and nerve supply of salivary glands
 Structure of salivary glands
 Histology of salivary glands
 Properties of saliva
 Composition of saliva

Saliva
 Saliva is a clear, tasteless, odorless,slightly acidic
(pH 6.8) viscid fluid, consisting of secretion from
salivary glands of the oral cavity.
 The whole saliva is a complex mixture of
fluids,containing a high population of normal
oral bacteria,desquamated epithelial cells and
transient residues of food or drink, following
their ingestion.

 Saliva is secreted by salivary glands.
 They are essentially exocrine glands that secrete
this valuable oral fluid,into the oral cavity
through a duct system.
Salivary
glands

DEVELOPMENT
 Salivary glands develop as an outgrowth of the
buccal epithelium.
 These outgrowths are first solid,
 Then canalize,
 They branch repeatedly to form duct system.
 Terminal parts of the duct system develop into
secretory acini.
BD Chaurasia, Human Anatomy Vol 3, 4th ed, 2004, Pg 133-37

 Parotid gland:
Arises in relation to the line along which the
maxillary and mandibular processes fuse to
form cheek.
Ectodermal
 Submandibular and Sublingual gland:
Arise in relation to the linguo-gingival sulcus.
Endodermal
Inderbir Singh, Human Embryology, 7th ed, 2001, Pg. 163

 Parotid gland and Submandibular gland
develops at 6th week of I.U life.
 Sublingual gland develops at 8th week of
I.U life.
 Minor salivary glands develop at 3rd month
of I.U life.
Inderbir Singh, Human Embryology, 7th ed, 2001, Pg. 163

Classification of salivary glands
 Based on their anatomical size
 MAJOR SALIVARY GLANDS
• Parotid gland
• Submandibular gland
• Sublingual gland
 MINOR SALIVARY GLANDS
• Buccal
• Labial
• Lingual(Von Ebner’s)
• Palatine
• Glossopalatine
Essentials of Medical Physiology; 5th edition;
K.Sembulingam,Prema Sembulingam

Based on their type of secretion
• Serous- made up of serous cells and secrete thin
watery saliva.
eg:parotid glands, lingual serous glands
• Mucous- made up of mucus cells and secrete
thick, viscous saliva with high mucus content.
eg:lingual mucus glands, buccal glands, palatal
glands
• Mixed-made up of both cells
eg-submandibular glands,sublingual glands,
labial glands

Anatomy of salivary glands
 Parotid gland
• Largest of all the salivary glands.
• Weighs -15gms
• Situated- below external acoustic meatus between
ramus of the mandible and sternocleidomastoid.
• A part of the gland forms a forward extension-
Accessory parotid gland- lies b/w zygomatic arch and
parotid duct.

 Capsule of Parotid- Investing Layer of deep cervical fascia
forms the capsule of parotid gland
 SURFACES AND ITS RELATIONS
1. Superior
a) Cartilaginous part of external auditory meatus
b) Posterior surface of TMJ
c) Auriculotemporal nerve
2. Superficial
a) Skin
b) Parotid fascia
c) Superficial fascia
3. Anteromedial
a) Lateral surface of TMJ
b) Posterior border of ramus of mandible
c) Masseter and Medial pterygoid

4. Posteromedial
a) Mastoid process
b) Styloid process
STRUCTURES WITHIN PAROTID GLAND
ARTERIES
a) External carotid artery
b) Maxillary artery
c) Superficial temporal artery
d) Posterior auricular artery
VEINS- Retromandibular vein
NERVE- Facial nerve

 Duct of the gland-Parotid duct {Stenson’s
duct}
 Thick walled, 5cm long
Duct opens
opp to upper
2nd molar
Atlas of Human Anatomy;5th edition; Frank.H.Netter

Submandibular gland
• Situated in the anterior part of digastric triangle.
• It is J-shaped indented by posterior border of
mylohyoid which divides it into 2 parts:
-large part superficial to muscle
-small part deep to muscle.
Duct of the submandibular gland- passes forward from
the deep part of the submandibular gland along the
floor of the mouth to open into the oral cavity at the
sublingual papilla under the tongue.

 Sublingual gland
• Smallest of all the salivary glands.
• Lies above mylohyoid, below mucosa of the floor of the
mouth.
• Opens into the floor of the mouth on the summit of the
sublingual fold and some join submandibular gland.
 Duct of sublingual gland- Bartholin’s duct

Minor salivary glands
Labial{superior And Inferior}Lips
BuccalCheeks
LingualTongue
PalatineHard palate,Soft palate,Uvula
GlossopalatineAnt.Faucial
pillar,Glossopalatine fold

Vascular and nerve supply of
salivary glands
 PAROTID GLAND
Arterial: Ext.Carotid Artery and its branches
Venous: Ext.Jugular Vein
Lymphatic: Upper deep cervical nodes
Nerve supply:
parasympathetic- secretomotor and reach the gland
through the auriculotemporal N.
sympathetic- derived from plexus around External Carotid A.
sensory-auriculotemporal N.

 SUBMANDIBULAR GLAND
Arterial: Facial Artery,Lingual Artery
Venous: Common Facial Vein /Lingual Vein
Lymphatic: Submandibular Lymph nodes
Nerve supply:
parasympathetic- chorda tympani N
sympathetic-plexus around facial N
sensory- lingual N

 SUBLINGUAL GLAND
Arterial:Lingual and Submental Arteries
Venous: Lingual Vein
: submental lymph nodes
Nerve and Lymphatic supply: same as submandibular gland

Structure of salivary glands
Salivary glands are made up of
acini.
Acinus- a small group of cells
surrounded by a central globular
cavity.
Each acini drains into
intercalated duct.
Intercalated ducts join to form
intralobular duct.
Intralobular ducts join to form
interlobular duct.
Interlobular ducts unite to form
the main duct of the gland.
Essentials of Medical Physiology; 5th edition;

 Intercalated ducts
 Lined by single layer of low cuboidal cells
 Contribute components like Lysozymes and
lactoferin.
 Striated ducts
 Largest portion of the ductal system
 Lined by layer of tall columnar cell, With large
centrally placed nuclei
 Secrete glycoproteins
 Site of electrolyte reabsorption of Na, Cl, K and
Bicarbonate
 Excretory ducts
 2 layers : mucosa and outer connective tissue
 Connective tissue allow passive stretching of
the duct to accomodate varying volumes of
saliva.

Properties of saliva
 Average daily flow- 750ml to 1lts
 Normal pH- 6.35-6.85
 Saliva flow
 Specific gravity-1.002-1.012
Unstimulated
0.3-0.4ml/min
Stimulated
0.2-7ml/min

 Freezing point- 0.07-0.34°C
 Tonicity – hypotonic to plasma
 Contribution from each major salivary gland
Gland Secretion %of
saliva
Parotid Watery 20
Submandibular Moderate
ly viscous
70
Sublingual Viscous 5

ACCORDING TO GORDON
NIKIFORUK
 WATER
 INORGANIC CONSTITUENTS
 Potassium
 Sodium
 Calcium
 Chloride
 Bicarbonate
 Inorganic phosphate
 Fluoride

 ORGANIC CONSTITUENTS
 Salivary proteins in digestive functions
 Amylase and other hydrolytic enzymes
 Salivary antibacterial substances
 Lysozyme
 Lactoperoxidase
 Lactoferrin
 Immunoglobulins
 Other salivary proteins with protective functions
 Glycoprotein
 Salivary agglutinins
 Salivary proteins which inhibit formation of
hydroxyapatite
 Statherin
 Proline rich proteins

Calcium
 Concentration of calcium in saliva increases slightly
from unstimulated to stimulated states of secretion.
 Range – 1-2 mmol/l
 In whole saliva, calcium is bound to proteins like
statherin and proline.
 Calcium not bound to proteins in saliva- occur as
ionized or non- ionized states.
 When saliva pH and ionic strength icreases at high
flow rate more calcium will be in non-ionized form

 Calcium carrying 2 positive charge can also be
strongly bound to ion species with 2 negative
charge
 Such compounds are citrates originating from
citric acid rich foodstuffs
 After exposure to such compounds, citrate
concentration in saliva is higher then calcium
 Therefore, ionised free calcium concentration in
saliva can be reduced to very low values which
affect saturation level with respect to
hydroxyapatite and lead to demineralisation of
teeth

Phosphate
 Inorganic phosphates consists of phosphoric acid,
dihydrogen phosphate,hydrogen phosphate and
phosphate.
 Occurs – ionized and un-ionized states.
 Range - 2-10mmol/l.
 Total phosphate concentration is determined by the
salivary flow.
 Concentration of phosphate decreases with
increasing salivary flow rate
 Lower the pH, lower is the phosphate concentration

Fluoride
 Its concentration depends on the fluoride
present in the environment mainly the
drinking water
 In low fluoride concentration areas, fluoride
in whole saliva may be lower than
1micromol/l.
Ole Fejerskov and Edwina Kidd, Dental Caries, the disease and its management, 2nd ed, 2008, Pg189-206

After ingestion of fluoride, in blood its
level increases in blood within 30mins-
1hr while minute amount excreted in
saliva
Fluoride in the duct saliva is 20-40%
lesser than its concentration in
plasma.

The fluoride concentration decreases
after initial exposure to oral cavity due to
oral clearance.
Tooth brushing before bedtime will
increase fluoride concentration due to
less oral clearance at night leading to
more fluoride exposure to oral cavity

Both in saliva, and more importantly, in
plaque, mineral calcium fluoride will
form.
The calcium fluoride functions as a slow
releaser of fluoride.
Fluoride diffusing into the
microorganisms prevents the enzyme
enolase from taking part in the glycolytic
pathway by binding Mg, which is needed
for optimum function of the enzyme.

DEGREE OF SATURATION AND
CRITICAL pH
• Saliva’s ion activity product (IAP)
(IAP)= (Ca2+)10 (PO4
3-)6 (OH-)2
• Solubility product of hydroxyapatite (SP)
 If IAP>SP , saliva is supersaturated REMINERALISATION OCCUR
 If IAP<SP, saliva is undersaturated DE-MINERALISATION OCCUR
 If IAP=SP, saliva is saturated NO REMINERALISATION NO DEMINERALISATION
pH value representing this situation is called critical pH
value (5.5) this is highly dynamic due to dependence on
calcium phosphate and hydroxyl ions

PROTEINS
 1 mm of whole saliva contains 1-2 mg of
proteins.
 Give viscosity to saliva.
 These are glycoproteins.
 They are either mucous or serous.

Mucous glycoproteins(mucins)
Acinar cell origin.
High molecular weight.
Contains >60% carbohydrates.
They are hydrophilic.
Hold water and are effective in
lubricating and maintaining a moist
mucosal surface-prerequisite for healthy
mouth.

Oligosaccharides in mucins prevent
the adhesion of bacterial cells to soft
tissues by inhibiting adhesins, the
reactive group on bacterial cell
surfaces.
Thus mucins help to protect the
mucosa from infections.
All of these protective activities are
reduced in dry-mouth patients leading
to more bacterial infections

Serous glycoproteins
Molecular weight is lower than that of
mucins.
Contains <50% carbohydrates.
Secreted from parotid and
submandibular glands
Salivary proteins like secretory
immunoglobulin A(IgA), lactoferrin,
peroxidases and agglutinins belong to
this group.

Calcium binding proteins
 Saliva is supersaturated with calcium and phosphate salts, so
some salts are needed to inhibit their spontaneous
precipitation in salivary glands.
 Statherin is present in parotid and submandibular saliva
 and promotes adhesion of Actinomyces viscous to tooth
surfaces.
 Due to the presence of Statherin, saliva can be supersaturated
wrt hydroxyapetite, thus facilitating remineralisation of early
carious lesions, without the spontaneous precipitation of
calcium phosphate , which would otherwise occur.

Proline rich proteins promotes adhesion
of Actinomyces viscous and
Streptococcus gordani to apatite surfaces
thereby inhibiting the hydroxyapetite
formation.
 Constitute 25-30% of all proteins in saliva.
 They are easily adsorbed from saliva to
hydroxyapatite surfaces.

Digestive enzymes
ENZYME SOURCE OF
SECRETION
ACTIVATOR ACTION
Salivary
amylase
All salivary
glands
Acid
medium
Converts
starch into
maltose
Maltase Major salivary
glands
Acid
medium
Converts
maltose into
glucose
Lingual lipase Lingual glands Acid
medium
Converts
triglycerides
of milk fat
into fatty
acids and
diacylglycerol
Lingual lipase – important for
digestion of milk fat in
newborns Essentials of Medical Physiology; 5th edition;

Antimicrobial proteins and
peptides
 Non-immunoglobulinproteins:
Protein Major function
Lysozyme Comes from minor salivary glands;antimicrobial
activity- muramidase;activates bacterial
autolysins that destroys cell walls.
Lactoferrin Iron binding glycoprotein;serous cells of
salivary glands;high affinity for iron and its
capacity to remove it from
bacteria;bacteriostatic,bactericidal,antiviral,
fungicidal,anti-inflammatory activity
Salivary peroxidase & myeloperoxidase Antimicrobial activity; decomposition of H₂O₂
Histatins Antifungal;antibacterial
Cystatins Antiviral;protease inhibitors

Agglutinins
Glycoproteins
Found in Parotid saliva
<0.1%
Interacts with unattached bacteria,
resulting in clumping of bacteria
into large aggregates, which are
easily flushed by saliva and
swallowed.

Immunoglobulins
 The immunoglobulins present in saliva are
secretory IgA, IgM and IgG.
 IgM and IgG enhance the phagocytosis action.
IgA
 In IgAs, the secretory immunoglobulins, the
immunoglobulin units form dimers and trimers around a J
chain and a polypeptide that comes from epithelial cells, the
secretory component (SC).
 It is resistant to proteolytic enzymes due to its association
with secretory component.

 It is present as local antibody system in the
plasma cells in the salivary glands.
 It provides local response to an antigen.
 Concentration of IgA in stimulated
submandibular and parotid salivary glands-
4mg/100ml.
 Increased concetration upto 30mg/100ml is
seen in the secretions of minor salivary
glands.

FUNCTIONSOF SALIVA
CLEANSING AND PROTECTIVE FUNCTIONS:
 Due to constant secretion of saliva, the
mouth and teeth are rinsed and kept free
from food debris; shed epithelial cells and
foreign particles.
 Prevents growth of bacteria by removing
materials, which may serve as culture media
for the growth of bacteria.
 Mucin protects the mouth by lubricating
K Sembulingam, Essentials of Medical Physiology, 4th
ed, 2006, Pg 197-203.

SPEECH
By moistening and lubricating the soft
parts of mouth and lips, saliva helps in
speech.
SWALLOWING
When food enters the mouth, saliva
moistens and dissolves it.
The moistened and masticated food is
rolled into a bolus. The mucin of saliva
moistens and lubricates the bolus and
facilitates swallowing.
ed, 2006, Pg 197-203.

DIGESTIVE FUNCTION
 Saliva has two digestive enzymes namely salivary
amylase and lingual lipase.
 Salivary amylase- is a carbohydrate splitting
(amylolytic) enzyme
 Acts on cooked and boiled starch and converts it
into maltose.
 When the bolus reaches the stomach and mixes
with gastric juice, the gastric acidity (pH 2) stops
the action of amylase.
 Salivary lipase- secreted from the lingual glands
a fat splitting enzyme which converts triglycerides
into fatty acids and 1,2-diacylglycerol.
ed, 2006, Pg 197-203.

Mucous membrane integrity
By salivary mucin & proline rich
proteins which have anticarcinogenic
effect
Maintains tooth integrity:
By preventing friction and thus
prevents wasting of hard tissue &
helps in remineralization
ed, 2006, Pg 197-203.

Regulation of water balance of body
When the body water content is
reduced, it decreases the salivary
secretion also. This causes dryness of
the mouth and induces thirst
When water is taken it quenches
and restores the body water content.

Excretory function
 It excretes some substances like mercury,
potassium iodide,
lead, and thiocynate.
 Saliva also excretes some viruses: rabies and
mumps.
 In some pathological conditions, saliva
excretes substances normally not found in
saliva such as glucose in diabetes mellitus.
 In certain conditions, some of the normal
constituents are excreted in large quantities.
Example, more urea is excreted in nephritis,
and more calcium is excreted in
hyperparathyroidism.
ed, 2006, Pg 197-203.

Antimicrobial Functions
Antibacterial : Lysozyme  Veillonella &
AA, lactoferrin  S. mutans,
lactoperoxidase-thoicynate system 
lactobacillus & streptococcus
Immunologic : IgA, IgG, IgM
Antifungal : neutral & basic histidine rich
peptides against Candida albicans
Antiviral : IgA neutralize viruses
ed, 2006, Pg 197-203.

Neutralization & buffering
An effective buffer system, responsible
constituents are bicarbonates,
phosphates & histidine rich peptides
Appreciation of taste
Taste is a chemical sensation. Saliva by
solvent action dissolves the solid food
substances, so that the dissolved
substances can stimulate the taste buds.
ed, 2006, Pg 197-203.

Functions of Saliva
Formation of Saliva
Regulation of salivary secretion
Factors affecting the salivary flow
Collection of saliva
Reflex
Oral clearance
 Role of Saliva in Dental Plaque
 Role of saliva in calculus formation
 Saliva buffer capacity and ph regulation
 Role of saliva in Dental Caries

FORMATION OF SALIVA
 Two stage process
1st stage: Production of primary saliva from
secretory end pieces which is an isotonic fluid
2nd stage: Primary saliva is modified as it passes
through striated and excretory ducts mainly by
reabsorption and secretion of electrolytes.
Final saliva secreted in oral cavity is hypotonic
in nature

 The fluid formation in salivary glands occurs
in the end pieces (acini).
 Initiated by binding of neurotransmitters
(acetylcholine or norephinephrine)
 This leads to opening of K+ and Cl- channels
and influx of sodium and calcium
 Due to high permeability of acinar tissue to
water, water enters into lumen
 This results to formation of primary saliva
which is isotonic
Edgar M, Dawes C, Mullane D, Saliva and Oral Health,
Dental Tribune Middle East & Africa Edition, 2014 Jan,
14-16

 From the lumen it passes through the ductal
system where it is further modified.
 Most of the modification occurs in the
striated ducts where reabsorption of sodium
and chloride takes place and the secretion is
changed from an isotonic solution to a
hypotonic one
Edgar M, Dawes C, Mullane D, Saliva and Oral Health,
14-16

REGULATION OF SALIVARY
SECRETION
Saliva is secreted continuously but the
quantity varies depending upon the
activity.
Secretion of saliva is regulated by
nervous mechanism.
No hormonal or chemical mechanism
is involved.
ed, 2006, Pg 197-203.

Salivary glands are under control of
autonomic nervous system and
receive efferent nerve fibres from both
parasympathetic and sympathetic
divisions.
ed, 2006, Pg 197-203.

Parasympathetic supply
Arise from the superior and the inferior
salivatory nuclei, situated in the pons (to
submandibular and sublingual glands)
and medulla (parotid gland), respectively.
Postganglionic fibres arising from
ganglion in pons supply submaxillary and
sublingual glands.
Postganglionic fibres from otic ganglion
supply parotid gland.
ed, 2006, Pg 197-203.

 Parasympathetic fibers
Arise from
superior
salivatory
nucleus in pons
Essentials of Medical Physiology; 5th edition;K.Sembulingam,Prema
Sembulingam
submandibular
and sublingual
salivary glands

 Parasympathetic fibers
Arises form
inferior salivatory
nucleus in
medulla
Parotid
salivary
gland
Essentials of Medical Physiology; 5th
edition;K.Sembulingam,Prema Sembulingam

K Sembulingam, Essentials of Medical Physiology, 4th ed, 2006,
Pg 197-203.

Sympathetic supply
 The sympathetic preganglionic fibres to
salivary arise from 1st and 2nd thoracic
segments of spinal cord.
 The postganglionic fibres from this ganglion
are distributed to the salivary glands along
the nerve plexus around the arteries
supplying the glands.
Pg 197-203.

Factors affecting the saliva flow
 Diurnal variation
 Age
 Sex
 Diet
 Source
 Type of stimulus

 Diurnal variation
-increases in daytime.
-appointment given at morning in
hyposalivation patient
 Age
-parotid saliva decreases with age
• new born-parotid saliva observed
• at 3-5yr of age- it increases
• at 8-10yr-flow rate is least in life
• at 10-29yr-moderate flow
• afterwards-decline phase occurs

 Sex- less in female
 Diet- increase with flavoured diet
 Source- saliva is secreted from
submandibular salivary gland is more than
that from other glands.
 Type of stimulus- increases in
parasympathetic stimulation and decreases
in sympathetic stimulation.

Collection of Saliva
Whole Saliva
1. Stimulation – suck sour candy or chew
paraffin or swab a solution of 2% citric
acid on the back and side of the tongue
at 15 secs interval.
2. Draining – head inclined forwards to
allow collection of saliva in the anterior
floor of the mouth and collect using
funnel.
3. Spitting – subject actively spits into
funnel at intervals
4. Suction – saliva ejector applied orally in
area of lower incisors and aspirated fluid
is collected.

Reflex regulation of salivary
secretion
Salivary reflexes are of two types:
 Unconditioned reflex
 Conditioned reflex

UNCONDITIONED REFLEX

CONDITIONED REFLEX

ORAL CLEARANCE
The oral cavity is frequently exposed to
substances with potentially harmful
properties.
An important function of saliva is
therefore to dilute and eliminate
substances.
This is a physiological process, usually
known as salivary clearance or oral
clearance.
Ole Fejerskov and Edwina Kidd, Dental Caries, the disease and its
management, 2nd ed, 2008, Pg189-206.

Clearance rate varies from individual to
individual and depends upon several
factors, most important being salivary
flow rate.
E.g : clearance rate is fastest during first
minutes after sugar exposure owing to
the effect of stimulated salivary flow.
management, 2nd ed, 2008, Pg189-206.

ROLE OF SALIVA IN PLAQUE
FORMATION
Formation of Pellicle:-
 All surfaces of the oral cavity are coated with a
pellicle.
 Within nanoseconds after vigorously polishing the
teeth, a thin, saliva-derived layer, called acquired
pellicle, covers the tooth surface. (Lendenmann et
al., 2000)
 Thickness : 1-10 µm
 This pellicle consists of numerous components,
including glycoproteins, proline-rich proteins,
phosphoproteins, histidine-rich proteins, enzymes
Newman, Takei, Klokkevold, Carranza, Cliinical Periodontology, 10th Edition, 170-175

First, a-amylase has been identified as a
constituent of the acquired enamel
pellicle (Orstavik and Kraus, 1973; 1974;
AlHashimi and Levine, 1989) and
May act as a receptor for bacterial
adhesion to the tooth surface.
Second, a-amylase has been detected in
dental plaque by immunochemical
(DiPaola et al., 1984), enzymatic, and
electrophoretic methods (Birkhed and
Skude, 1978).
Newman, Takei, Klokkevold, Carranza, Cliinical
Periodontology, 10th Edition, 170-175

Third, as previously stated, the enzyme
has also been found to interact with
several species of oral streptococci, which
are among the first to colonize dental
plaque.
Finally, the fact that a-amylase binds to
teeth as a constituent of enamel pellicle
(Al-Hashimi and Levine, 1989) and
promotes the adhesion of amylase-
binding bacteria to hydroxyapatite (HAP)
in vitro (see the following) argues for a
potential role in bacterial adhesion.

Calculus Formation :-
Calculus is dental plaque that has
undergone mineralization within 4-8
hours.
Saliva is the source of mineralization for
supragingival calculus.
50%mineralization occurs in 2 days and
60%-90% mineralization occurs in 12
days.

An increase in pH of the saliva causes
precipitation of calcium phosphate salts
by lowering the precipitation constant.
The pH may be elevated by the loss of
carbon dioxide and the formation of
ammonia by dental plaque bacteria or by
protein degradation during stagnation.

Colloidal proteins in saliva bind calcium
and phosphate ions and maintain a
supersaturated solution with respect to
calcium phosphate salts.
With stagnation of saliva, colloids settle
out, and the supersaturated state is no
longer maintained, leading to
precipitation of calcium phosphate salts.

Saliva buffer capacity and pH
regulation
 Critical pH
• When ion activity product is equal to the
solubility product of hydroxyapatite the
solution is saturated and no
demineralization or remineralization will
occur.
• Thus the pH value that corresponds to this
level of saturation is called as critical pH.
• Value-5.2 to 5.5

Various buffer systems
 Phosphate Buffer
• Unstimulated saliva has dihydrogen
phosphate and stimulated saliva has
hydrogen phosphate.
• The pK value value is 7 for human saliva.
• pK- dissociation constant indicating when
half of the buffer is in acid form and half is
base form.
• As phosphate level decreases with increase
salivary flow rate contribution of phosphate
to buffer system also decreases
management, 2nd ed, 2008, Pg189-206

 Bicarbonate Buffer
• As there is a huge variation in the
concentration of bicarbonate ions in
stimulated and unstimulated saliva, the
buffering capacity is more pronounced in
unstimulated saliva.
• The pK value is close to 6.
• Same as phosphate buffer.
• Buffers hydrogen ions equal to half its
concentration at pK for carbonic acid.

• In the mouth extension phase buffering
occurs, allowing further buffering of
bicarbonate.
• It helps in clearing of saliva.
• Saliva can overcome acidic conditions in
dental plaque after dilution and thereby
increasing the pH.

 Protein Buffer
• Proteins in saliva can act as buffers when
is above or below their isoelectric point.
• Isoelectric point between pH 5-9.
• Less buffering capacity then phosphate and
bicarbonates
• Apart from buffering capacity,some proteins
increase the viscosity of saliva when pH
increases.
• Protects teeth against acid by forming a
diffusion barrier.

ROLE OF SALIVA IN CARIES
 Teeth are ‘bathed in saliva’.
 So the composition and the amount of saliva
play a significant role in maintaining the
integrity of the tooth tissues.
 Under physiologic conditions saliva is
supersaturated with respect to
hydroxyapatite and fluorapatite.
management, 2nd ed, 2008, Pg189-206

 When the pH in the surrounding medium
decreases, the solubility of the tooth mineral
apatite increases.
 Below this pH (critical pH), fluids are
undersaturated with respect to
hydroxyapatite
 So environment remains undersaturated
with respect to hydroxyapatite.
 Therefore, carious lesion develops.

The analysis of saliva has
two purposes:
•to identify individuals with
disease and
•to follow the progress of the
affected individual under treatment
(Copeland, 1974;
Aguirre et al, 1993).
SALIVA- A
DIAGNOSTIC TOOL

WHY SALIVA?
 Collection is relatively non-invasive.
 Range of potential analysis as broad as
plasma
Bacteria in saliva
Salivary ions
Secreted salivary proteins
Inflammatory mediators
Proteins, metabolites, from other parts of
the body
Nucleic acids (from the mouth and other
regions)
 Chair side diagnostic testing

It helps in diagnosis of systemic diseases
as :-
Sjogren’s syndrome
 Cystic fibrosis
Hormonal dysfunction- diabetes, pancreatitis,
adrenal-cortex disease, thyroid disease,
acromegaly, menopause
Hypertension
Obesity and hyperlipidemia
Alcoholic cirrhosis
Malnutrition
Neurologic diseases- Parkinson’s disease,
Bell’s and cerebral
Psychogenic diseases

Dental Caries.
Prior to the development of dental
caries :
 a decrease in the salivary flow rate
and buffering capacity,
increase in the streptococcus mutans
count and lactobacillus in saliva which
are the prime micropathogens of
dental caries.
Sindhu S, Jagannathan N, Saliva: A Cutting Edge in Diagnostic
Procedures, Journal of Oral Diseases Volume 2014, 1-9.

 High levels of mutans streptococci, i.e. >105
colony forming units (CFUs) per ml of saliva,
are associated with an increased risk of
developing caries.
 High levels of Lactobacilli (>105 CFUs per ml
saliva) are found amongst individuals with
frequent carbohydrate consumption and are
also associated with an increased risk of
caries.

Cardiovascular disease
Elevated salivary lysozyme levels, a
biomarker for oral infection and
hyperglycemia, has also shown a
significant association with hypertension,
an early stage of CVD.
) Malamud D, Rodriguez IR, Saliva as a Diagnostic Fluid, Dent
Clin North Am. 2011 January ; 55(1): 159–178.

 Renal disease
Salivary phosphate has been successfully
used as a clinical biomarker for
hyperphosphatemia, which is an important
contributor to cardiovascular calcification in
chronic renal failure (CRF)
 Evaluation of phosphate levels in saliva are
correlated positively with serum creatinine
and the glomerular filtration rate.

Psychological research
Typical markers that have been identified
include salivary amylase, cortisol,
lysozyme and secretory IgA.
Salivary testosterone levels have been
associated with increased aggressive
behaviour and also with athletic

Diabetes
It is relatively easy to measure
salivary glucose, due to the
sources of this material in the oral
cavity, salivary glucose levels do
correlate with blood glucose levels.

Forensics
Salivary test have been used for a
wide variety of forensic studies.
Samples can be obtained from
 drinking glasses,
cigarette buds,
envelopes,
Then it is used to detect blood-group
substances or salivary genetic
(primarily proline-rich protein
polymorphisms).

Periodontium
 The potential salivary gland markers for
periodontal diseases include a variety of
serum and saliva molecules chiefly
immunoglobulins, enzymes, gingival
crevicular fluid, bacterial components,
volatile compounds, and phenotypic
markers.
The salivary concentrations of these
immunoglobulins show a rise in
periodontitis which decreases
considerably following periodontal
therapies

Decreased levels of lysozyme in patients
are usually considered a risk factor for
periodontal diseases
Lactoferrin is unregulated in the salivary
secretions in gingival inflammation and
periodontal diseases as compared to
normal healthy individuals.

Hormone Levels.
Salivary cortisol is proposed as the
best screening methodology for
detection of Cushing’s syndrome.
Abnormal salivary diurnal cortisol
variations are also a predictive
marker of breast cancer patients,
especially in metastasis.

Wound Healing.
Saliva has a play in wound healing
apart from its role in preventing
wound infections.
The EGF present in saliva has
angiogenic and proliferative effects
which enhances the wound

Saliva also replaces platelets in the
thrombin generation.
A relatively increased level of
salivary kallikrein has a major role in
vasodilatation around mucosal
injuries to facilitate defence and
healing of injured areas.

Other Systemic Disorders.
Anxiety and depression lead to a
decrease in salivary flow rate resulting in
xerostomia.
Acute stress conditions also lead to
significant salivary changes with a
prominent decrease in secretary IgA and
increase in salivary amylase.
There is also a prompt change in the
bacterial adherence to the mucins.

Saliva has been used to assess the salivary
creatinine levels in diagnosis and
monitoring of the kidney failure
In Cystic fibrosis an elevation of
electrolytes like sodium, chloride, calcium,
and phosphorous is seen. The lipid levels
of submandibular saliva are considerably
raised leading to increased calculus
formation. Abnormally elevated
prostaglandins E2 and poor biologic
activities of EGF.

Autoimmune Disorders.
Sjogren’s Syndrome: Autoantibodies of
IgA class are secreted by the salivary
gland which are then secreted into the
saliva much before it is secreted in the
serum.
 Reduced quantity of salivary secretion
results in dryness of mouth.

A wide fluctuation in the salivary peptides
and nonpeptides seen
A decrease in phosphate levels is also
observed.

• Iron deficiency anaemia
Agarwal and coworkers observed that
saliva contains ferritin and changes in
ferritin levels have been observed in iron
deficiency and its levels in saliva were
much higher than the normal.
Nithya et al. (2012) observed a threefold
rise in the salivary ferritin levels in iron
deficient patient compared to normal
individuals.

 Diagnostic use of Saliva
 Saliva as a biomarker
 Effect of Drugs on Saliva
 Effect of saliva on restorative materials
 Applied physiology
 Artificial saliva
 Recent advances
 References

Title Saliva: A Cutting Edge in Diagnostic Procedures
Level of evidence 1b
Author Senthamil Sindhu and Nithya Jagannathan
Journal Journal of Oral Diseases Volume 2014, Article ID 168584, 8 pages
Abstract Considering the microconcentration of salivary constituents, saliva is explored
be diagnostic tool as it also meets the demands for an inexpensive,
and easy to use screening method. .The investigative use of saliva is not being
applied only in dental health but also in various other systemic disorders. This
has triggered its application as a specific and sensitive biomarker in
genomics, and transcriptomics. This review discusses the basics of salivary
diagnostics, expectoration techniques, and its application in various local and
systemic disorders
Conclusion The saliva has requisite advantages compared to other body fluids and is a convenient
simple point of care diagnostic tool.

Applied physiology
Xerostomia
 Dry mouth, cotton mouth.
 Due to hyposalivation or aptyalism
 Causes :
 Dehydration- Excess sweating, diarrhea.
 Sjogren’s syndrome
 Radiotherapy
 Trauma to gland or their ducts
 Absence of glands
 Drugs
 Shock
 Smoking
 Renal failure
 Systemic diseases- HIV, Diabetes mellitus, Sarcoidosis
Pg 197-203

Ole Fejerskov and Edwina Kidd, Dental Caries, the disease and its management, 2nd ed, 2008,

MANAGEMENT
•The general approach to
treating patients with
hyposalivation and xerostomia is
directed at palliative treatment
for the relief of symptoms and
prevention of oral
complications:
Textbook of oral medicine, 2nd edition ,Anil ghom

•Consult with physician to
decrease drug dose, alter drug
dosages, or substitute one
xerostomic medication for a
similar-acting drug with fewer
salivary side effects.

• Symptomatic Treatments:
• Sip water frequently all day long
• Restrict caffeine intake
• Avoid mouth rinses
containing alcohol
• Humidify sleeping area
• Coat lips with lubricant.

Pharmacotherapy with salivary
stimulants.
 Pilocarpine and Bromhexine can be used.
 Pilocarpine- 5 milligrams three times per
day
 Bromhexine-
Children(1-5 years): 4mg twice a day
Children(5-10 years): 4mg thrice a day
Adults: 8mg thrice a day

Salivary Substitutes
 The primary functions of the salivary
substitutes are to lubricate the oral soft
tissue, to relieve the subjective xerostomia,
and to protect the teeth from
demineralization.
 carboxymethyl cellulose, mucin,
hydroxyethyl cellulose, water-glycerin,
and glycerate polymer

Salivary stimulants
 Stimulation of salivary output can be
achieved using pharmacological agents
known as "sialogogues."
 The use of sugar free gum, lemon drops or
mints are conservative methods to
temporarily stimulate salivary flow in
patients with medication xerostomia or with
salivary gland dysfunction.
 Biotene chewing gum
 Xylitol chewing gum

Hypersalivation
Excess secretion of saliva
= ptyalism, sialorrhea, sialism,
sialosis
Caused in pregnancy
Occurs in :
 Diseases of esophagus, stomach and intestine
 Cerebral stroke
 Nausea and vomiting
 Neoplasm of mouth or tongue
 Neurological disorders like cerebral palsy and
mental retardation
Pg 197-203

Drooling
Uncontrolled flow of saliva outside the
mouth.
Occurs due to excess production of
in association with inability to retain
saliva within the mouth.
Conditions
 Teeth eruption in children
 Upper respiratory tract infection
 Nasal allergies in children
 Difficulty in swallowing
 Tonsillitis
 Peritonsillar abscess
 Bells palsy
Pg 197-203

Management of
Hypersalivation and Drooling
 Treatment in children: No treatment
generally required in children below 4years
of age with mild or moderate amount of
drooling, which may improve spontaneously.
 Removal of local factors- Nasal airway
obstruction
 Atropine:
Children: 0.01mg/kg every 4-6 hours.
Adults: 0.4mg/kg every 4-6 hours.

Chorda Tympani Syndrome
Condition characterized by sweating
while eating.
During the regeneration of nerve fibres
following trauma or surgical division,
some of the nerve fibres of salivary
which pass through chorda tympani
branch of facial nerve may deviate and
join with the nerve fibres supplying seat
glands.
When food is placed in the mouth,
salivary secretion is associated with
secretion.
Pg 197-203

Mumps (Viral Parotitis) :
 Most common salivary gland disease
before use of vaccination.
 Caused by paramyxovirus
 Incubation period is 14-21 days.
 Symptoms :
 Enlargement of gland
 Pain
 Swelling
 Fever
 Malaise
 Chills
 Sore throat
Pg 197-203

Management
 Vaccination: Prevention with live attenuated
vaccine. Given in 12-15 months of age.
Repeated at he age of 4-5 years
 Relief of pain and swelling
 Rest
 Diet restriction: Avoid sour foods and drinks
to decrease salivary gland discomfort.

ARTIFICIAL SALIVA
 Artificial saliva is a product that is used by
people who have too little of their own
naturally occurring saliva (a condition known
as dry mouth).
 Its pH buffering capacity is similar to normal
saliva and has excellent caries preventive
effect.
 They do not contain the digestive and
antibacterial enzymes and other proteins or
minerals present in real saliva
http://www.ada.org/en/science-research/ada-seal-of-
acceptance/product-category-information/saliva-artificial

Composition:
Carboxymethyl cellulose: 10 gm/l
Sorbitol: 30 gm/l
Potassium chloride: 1.2 gm/l
Sodium chloride: 0.843 gm/l
Magnesium chloride: 0.051 gm/l
Calcium chloride: 0.146 gm/l
Dipotassium hydrogen phosphate: 0.342
gm/l

Why use artificial saliva?
Saliva coats and lubricates tissues in the
mouth.
It helps cleanse the mouth and begins
digestive process as we chew.
When the saliva glands do not produce
enough saliva, the mouth becomes dry.
Speaking, chewing and swallowing are
made easier when the mouth is moist.

Commercially available artificial
saliva products
 Gels
• GC-dry mouth moisturizing gel
• Biotene-oral balance mouth moisturizing gel
 Sprays
• Biotene- moisturizing mouth spray
 Mouthwash
• Biotene-dry mouthwash
• ICPA wet mouth- dry mouthwash
• Dr. Dentaids Salive drymouthwash

RECENT ADVANCES
 Salivary Proteome.
 A landmark accomplishment in the field of salivary
diagnostics was the identification of about 1166
proteins in human saliva which provided
boundaries for clinical diagnostic application.
 This complex set of proteins, the expression of
which is modified by specific genome, is called
genome.
 Salivary proteome serves as biomarkers for oral
cancer and Sjogren’s syndrome.

Nanobiochip Technology.
They are rapid tests which aid in making a
rapid clinical decision making.
Nanobiochip technology is based on two
types of systems.
The first system is microbead array, wherein
micropits within the silicon wafers are
subjected with a variety of chemically
sensitized bead microreactors.
The sensor system is based on biomicro
electromechanical system that has a
processing unit in analogue with the central
processing unit.
Sindhu S, Jagannathan N, Saliva: A Cutting Edge in Diagnos

 Biochip technology involves fluid processing to
detect the pH, local electrolytes, metal cations,
chemical environment, sugar, toxins, antibodies,
and proteins.

MyPerioID and MyPerioPath are DNA
based saliva tests to determine the type
and concentration of bacteria that cause
periodontal disease.
MyPerioID test also determines the
genetic susceptibility to periodontal
disease and identifies patients of risk.

 Oral fluid nanosensor
 Test is a micro electromechanical system that is
capable of real time, ultrasensitive, ultraspecific
detection of salivary protein and RNA biomarkers.
 It is used for the detection of salivary biomarkers
for oral cancer patients.

OraQuick is an antibody test which
detects the HIV1 and HIV2 in the
saliva, serum, and plasma and is a
quick chair side test which provides
results in 20 minutes.

REFERENCES
1) K Sembulingam, Essentials of Medical
Physiology, 4th ed, 2006, Pg 197-203.
2) Ole Fejerskov and Edwina Kidd, Dental Caries, the
disease and its management, 2nd ed, 2008,
Pg189-206.
3) Kumar GS, Orban’s Oral Histology and
Embryology, 12th Edition, 2007, Pg 258-262.
4) BD Chaurasia, Human Anatomy Vol 3, 4th ed,
2004, Pg 133-37.

5) Inderbir Singh, Human Embryology, 7th ed, 2001, Pg. 163.
6)https://www.google.com/search?biw=1366&bih=600&tbm=i
sch&sa=1&q=enzymes+clipart&oq=enzymes+clipart&gs_
l=img.3
7) Katie P. Wu et al, Relationship between Unstimulated Salivary
Flow Rate and Saliva Composition of Healthy Children in
Taiwan, Chang Gung Med J Vol. 31 No. 3, May-June 2008
8) Fenoll-Palomares C et al, Unstimulated salivary flow rate, pH
and buffer capacity of saliva in healthy volunteers, Rev Esp
Enferm Dig. 2004 Nov;96(11):773-83

9) Catalán MA, Nakamoto T, Melvin JE, The salivary gland
fluid secretion mechanism, The Journal of Medical
Investigation Vol. 56 Supplement Dec 2009.
10) Scannapieco MA, Torres G, Levine MJ, Salivary a-
Amylase: Role in Dental Plaque and Caries Formation
Critical Reviews in Oral Biology and Medicine,
4(3/4):301-307.
11) Textbook of Medical Physiology, Guyton and Hall,
12th Edition, Elsevier, Pg 665-668.
12) Edgar M, Dawes C, Mullane D, Saliva and Oral Health,
14-16.

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