Vamc saliva /orthodontic courses by Indian dental academy

SALIVA
&
SALIVARY GLANDS
INDIAN DENTAL ACADEMY
LEADER IN CONTINUING Education
www.indiandentalacademy.com

www.indiandentalacademy.co
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CONTENTS:
INTRODUCTION.
DEVELOPMENT OF SALIVARY
GLANDS.
CLASSIFICATION OF SALIVARY
GLANDS.
COMPOSTION OF SALIVA.
FUNCTIONS OF SALIVA.
ANATOMY OF SALIVARY GLANDS.
PROSTHODONTIC
CONSIDERATIONS.
BIBLOGRAPHY.

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INTRODUCTION

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The oral cavity has a moist
environment and a film of fluid constantly
occupies the space between the lining mucosa
and the teeth. This fluid is know as Saliva.
More than 99% of saliva is water and it has
been estimated that the total volume of saliva
produced in 24 Hrs is about 640ml.

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DEFINITION :
Stanlay Jablonski’s dictionary of dentistry :
Clear, slightly acid, sometimes viscid mixture of
secretions of the salivary glands and gingival fluid
exudates.
Stedman’s medical dictionary 26th edition :
Saliva is a clean, tasteless, odorless slightly
acidic viscous fluid, consisting of secretions from
the parotid, sublingual, submandibular salivary
glands and the mucous glands of oral cavity

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Saliva is a complex fluid produced by SalivarySaliva is a complex fluid produced by Salivary
Glands.Glands.
In Humans there are:In Humans there are:
1.] Three Major Salivary glands1.] Three Major Salivary glands
2.] Many minor salivary glands.2.] Many minor salivary glands.
The major salivary glands are located outsideThe major salivary glands are located outside
the oral cavity and have extended duct system tothe oral cavity and have extended duct system to
discharge their secretions.discharge their secretions.
In contrast, the minor salivary glands areIn contrast, the minor salivary glands are
located just below and within the mucous membraneslocated just below and within the mucous membranes
and therefore have short duct systems.and therefore have short duct systems.

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Development of the salivary glandsDevelopment of the salivary glands
A salivary gland arises as a focal thickening ofA salivary gland arises as a focal thickening of
the oral epithelium that grows into the underlyingthe oral epithelium that grows into the underlying
ectomesenchyme to form a small bud connected toectomesenchyme to form a small bud connected to
the surface by a trailing cord of epithelium. At thethe surface by a trailing cord of epithelium. At the
same time ectomesenchymal cells condense aroundsame time ectomesenchymal cells condense around
this bud. The epithelial bud grows into anthis bud. The epithelial bud grows into an
extensively branched system of cords of cells thatextensively branched system of cords of cells that
are first solid but gradually develop a lumen andare first solid but gradually develop a lumen and
become ductsbecome ducts..

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• The parotid glands begin to
develop at 4-6 weeks
• The submandibular glands at 6
weeks
• The sublingual and minor
salivary glands at 8-12weeks

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FORMATION OF SALIVAFORMATION OF SALIVA::
Saliva is produced in and secreted
from salivary glands. The basic
secretory units of salivary glands
are clusters of cells called an acini.
These cells secrete a fluid that
contains water, electrolytes, mucus
and enzymes, all of which flow out
of the acinus into collecting ducts.

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Within the ducts, the composition
of the secretion is altered. Much of
the sodium is actively reabsorbed,
potassium is secreted, and large
quantities of bicarbonate ion are
secreted.
Small collecting ducts within
salivary glands lead into larger
ducts, eventually forming a single
large duct that empties into the
oral cavity

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CLASSIFICATION OF SALIVARYCLASSIFICATION OF SALIVARY
GLANDS:GLANDS:
The salivary Glands are classified as:The salivary Glands are classified as:
EXOCRINE:EXOCRINE: As they have duct system.As they have duct system.
COMPOUND TUBULOACINAR:COMPOUND TUBULOACINAR: As theyAs they
have a branched duct system with bothhave a branched duct system with both
tubular and acinar shaped end pieces.tubular and acinar shaped end pieces.
MEROCRINE:MEROCRINE: As they function repeatedly.As they function repeatedly.

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1.]Salivary glands of mammalian species may also1.]Salivary glands of mammalian species may also
be divided into major and minor salivary glands.be divided into major and minor salivary glands.
Major Salivary glandsMajor Salivary glands are:are:
Parotid gland.Parotid gland.
Submandibular gland.Submandibular gland.
Sublingual gland.Sublingual gland.
MMinor Salivary Glandsinor Salivary Glands are:are:
Labial,Lingual,Palatal,Buccal,Glossopalatina andLabial,Lingual,Palatal,Buccal,Glossopalatina and
Retro molar glands.Retro molar glands.
2.]Salivary glands can also be classified by the type2.]Salivary glands can also be classified by the type
of secretionof secretion
as Mucous, Serous and Mixed.as Mucous, Serous and Mixed.

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COMPOSITION OF SALIVA:COMPOSITION OF SALIVA:
Saliva contains 99% of water with a solid matterSaliva contains 99% of water with a solid matter
consisting of equal parts of organic and inorganicconsisting of equal parts of organic and inorganic
components. It is hypotonic with PH of 5.6-8[6.7]components. It is hypotonic with PH of 5.6-8[6.7]
and with a specific gravity of 1.002-1.008.and with a specific gravity of 1.002-1.008.

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Inorganic components
Calcium and phosphate
Help to prevent dissolution of dental enamel
Calcium
1,4 mmol/l (1,7 mmol/l in stimulated saliva)
only cca 50% in ionic form
sublingual > submandibular > parotid
Phosphate
6 mmol/l (4 mmol/l in stimulated saliva)
90% in ionic form
pH around 6 - hydroxyapatite is unlikely to dissolve
Increase of pH - precipitation of calcium salts =>
dental calculus

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Bicarbonate
Buffer
Low in unstimulated saliva, increases
with flow rate
Pushes pH of stimulated saliva up to
8
Defence against acids produced by
cariogenic bacteria
Derived actively from CO2 by
carbonic anhydrase

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Other ions
FluorideFluoride
Low concentration, similar to plasmaLow concentration, similar to plasma
ThiocyanateThiocyanate
AntibacterialAntibacterial
Higher conc. => lower incidence of cariesHigher conc. => lower incidence of caries
Smokers - increased conc.Smokers - increased conc.
Sodium, potassium, chloride
Lead, cadmium, copper
May reflect systemic concentrations - diagnosticsMay reflect systemic concentrations - diagnostics

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Organic components
Mucins
Proline-rich proteins
Amylase
Lipase
Peroxidase
Lysozyme
Lactoferrin
Salivary IgA
Histatins
Statherin
Blood group substances, sugars, steroid hormones,
amino acids, ammonia, urea

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Variations in salivary composition
Parotid secretion increased amylase content
Submandibular secretion increased calcium
concentrations

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FUNCTIONS OF SALIVA:FUNCTIONS OF SALIVA:
DIGESTIVE:DIGESTIVE:
Saliva is important for digestion.It providesSaliva is important for digestion.It provides
taste acuity,neutralizes esophagealtaste acuity,neutralizes esophageal
contents,dilutes gastric chyme,forms foodcontents,dilutes gastric chyme,forms food
bolus and because of its amylase contents,bolus and because of its amylase contents,
breaks down starch.breaks down starch.

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PROTECTION:PROTECTION:
Its glycoprotein content makes salivaIts glycoprotein content makes saliva
mucinous,protects the lining mucosa bymucinous,protects the lining mucosa by
forming a barrier against noxious stimuli,forming a barrier against noxious stimuli,
microbial toxins,and minor trauma.microbial toxins,and minor trauma.
Saliva’s fluid consistency provides aSaliva’s fluid consistency provides a
mechanical washing action,which flushesmechanical washing action,which flushes
away nonadherent bacterial and acellularaway nonadherent bacterial and acellular
debris from the mouth.debris from the mouth.

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ORAL HYGIENE:ORAL HYGIENE:
The oral cavity is almost constantly flushed withThe oral cavity is almost constantly flushed with
saliva, which floats away food debris and keeps thesaliva, which floats away food debris and keeps the
mouth relatively clean.mouth relatively clean.
Flow of saliva diminishes considerably duringFlow of saliva diminishes considerably during
sleep, allow populations of bacteria to build up insleep, allow populations of bacteria to build up in
the mouth -- the result is dragon breath in thethe mouth -- the result is dragon breath in the
morning.morning.
Saliva also contains lysozyme, an enzyme thatSaliva also contains lysozyme, an enzyme that
lyses many bacteria and prevents overgrowth oflyses many bacteria and prevents overgrowth of
oral microbial populations.oral microbial populations.

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MAINTANANCE OF PH/BUFFERING ACTION:MAINTANANCE OF PH/BUFFERING ACTION:
Many bacteria require specific pH conditions forMany bacteria require specific pH conditions for
maximum growth.The buffering capacity of salivamaximum growth.The buffering capacity of saliva
prevents potential pathogenic bacteria fromprevents potential pathogenic bacteria from
colonizing the mouth by denying them optimalcolonizing the mouth by denying them optimal
environment conditions. The main buffering actionenvironment conditions. The main buffering action
of saliva is with its bicarbonate and phosphate ions.of saliva is with its bicarbonate and phosphate ions.
HEALING OF WOUNDS:HEALING OF WOUNDS:
Salivary epidermal growth factors fromSalivary epidermal growth factors from
submandibular and parotid glands helps in healingsubmandibular and parotid glands helps in healing
cutaneous wounds.cutaneous wounds.

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MAINTAINENCE OF TOOTH INTEGRITY:MAINTAINENCE OF TOOTH INTEGRITY:
Saliva is saturated with calcium and phosphateSaliva is saturated with calcium and phosphate
ions.The high ionic concentration of these ions inions.The high ionic concentration of these ions in
saliva ensures that ionic exchange with the toothsaliva ensures that ionic exchange with the tooth
surface is directed to the tooth.Interaction withsurface is directed to the tooth.Interaction with
saliva results in post eruptive maturation whichsaliva results in post eruptive maturation which
increases surface hardness,decreases permeabilityincreases surface hardness,decreases permeability
and increases the resistance of enamel to theand increases the resistance of enamel to the
carious process.carious process.
REMINERALIZATION:REMINERALIZATION:
The stabilized super saturation of saliva providesThe stabilized super saturation of saliva provides
the driving force for the initial protection ofthe driving force for the initial protection of
enamel surface and remineralization of earlyenamel surface and remineralization of early
subsurface lesions.subsurface lesions.

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RETENTION OF DENTURESRETENTION OF DENTURES::
Saliva plays an very important role in theSaliva plays an very important role in the
success of dentures by helping in retention ofsuccess of dentures by helping in retention of
dentures. Saliva forms a thin layer betweendentures. Saliva forms a thin layer between
the denture and the underlying tissues,the denture and the underlying tissues,
which provides retention.which provides retention.

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ANTI BACTERIAL ACTIVITYANTI BACTERIAL ACTIVITY::
Saliva exerts a major ecological influence on theSaliva exerts a major ecological influence on the
microorganisms that attempt to colonize the oralmicroorganisms that attempt to colonize the oral
tissues.tissues.
Lysozyme is an enzyme present in saliva that canLysozyme is an enzyme present in saliva that can
hydrolyze bacterial cell walls.hydrolyze bacterial cell walls.
Salivary Lactoferrin binds free iron and is so doingSalivary Lactoferrin binds free iron and is so doing
deprives bacteria of this essential element.deprives bacteria of this essential element.

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ANTI FUNGAL ACTIVITY:ANTI FUNGAL ACTIVITY:
Antifungal activity of saliva is by neutralAntifungal activity of saliva is by neutral
and basic histidine rich proteins.and basic histidine rich proteins.
ANTI VIRAL ACTIVITY:ANTI VIRAL ACTIVITY:
This is produced byThis is produced by
*Direct neutralization of viruses by antibodies in*Direct neutralization of viruses by antibodies in
saliva.saliva.
*Oral mucosal antibodies may act via saliva.*Oral mucosal antibodies may act via saliva.
*Salivary mucins has an antiviral effect.*Salivary mucins has an antiviral effect.

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ANATOMY OF SALIVARY GLANDS:ANATOMY OF SALIVARY GLANDS:
PAROTID GLANDPAROTID GLAND:: The Parotid,which is theThe Parotid,which is the
largest gland,is located anterior to the externallargest gland,is located anterior to the external
acoustic meatus and mastoid process.,inferior toacoustic meatus and mastoid process.,inferior to
the zygomatic arch,lateral and posterior to thethe zygomatic arch,lateral and posterior to the
ramus of the mandible and on the surface of theramus of the mandible and on the surface of the
masseter muscle.masseter muscle.

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Parotid glands produce a serous, wateryParotid glands produce a serous, watery
secretion. The Parotid gland is enclosed in asecretion. The Parotid gland is enclosed in a
well formed capsule,with its superficialwell formed capsule,with its superficial
portion lying in front of the external ear andportion lying in front of the external ear and
its deeper part filling the Retromandibularits deeper part filling the Retromandibular
fossa.fossa.
The Gland is anatomically closely associatedThe Gland is anatomically closely associated
with Facial Nerve,External carotid Artery,with Facial Nerve,External carotid Artery,
Retromandibular Veins and NumerousRetromandibular Veins and Numerous
cervical lymph nodes.cervical lymph nodes.

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The Parotid ductThe Parotid duct [[stensons ductstensons duct]] extends from theextends from the
lateral surface of the gland,lateral surface of the gland,
anteriorly cross the masseteranteriorly cross the masseter
muscle and the buccal fat pad.muscle and the buccal fat pad.
It pierces the fat pad andIt pierces the fat pad and
buccinator muscle to openbuccinator muscle to open
into the oral cavity in ainto the oral cavity in a
papilla opposite the crown ofpapilla opposite the crown of
the second maxillary molar tooth.The epithelium ofthe second maxillary molar tooth.The epithelium of
the duct becomes continuous with the mucousthe duct becomes continuous with the mucous
membrane of the mouth.membrane of the mouth.

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BLOOD SUPPLYBLOOD SUPPLY-- The Parotid gland receives itsThe Parotid gland receives its
blood supply from branches of the external carotidblood supply from branches of the external carotid
artery.artery.
InnervationInnervation --
Sympathetic - Cranial Cervical SympatheticSympathetic - Cranial Cervical Sympathetic
Ganglion (CCSG).Ganglion (CCSG).
Parasympathetic - Via parasympathetic fibers ofParasympathetic - Via parasympathetic fibers of
the glosso pharyngeal nerve from the otic ganglion.the glosso pharyngeal nerve from the otic ganglion.

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SUB MANDIBULAR GLAND:SUB MANDIBULAR GLAND:
The sub mandibular gland is also envelopedThe sub mandibular gland is also enveloped
by well formed capsule,It is located in theby well formed capsule,It is located in the
anterior partanterior part
of digastric triangle behindof digastric triangle behind
and below the free borderand below the free border
of the mylohyoid muscle,of the mylohyoid muscle,
with a small extension lyingwith a small extension lying
above the mylohyoid.above the mylohyoid.

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sub mandibular glands produce a mixedsub mandibular glands produce a mixed
serous and mucous secretion.serous and mucous secretion.
The submandibular ductThe submandibular duct [[Wharton's ductWharton's duct]]
extends anteriorly,in the floor of the mouth,toextends anteriorly,in the floor of the mouth,to
open into the oral cavity at the sublingualopen into the oral cavity at the sublingual
papilla at the side of the frenulum of tongue.papilla at the side of the frenulum of tongue.

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Blood supplyBlood supply::
The submandibular gland receives its bloodThe submandibular gland receives its blood
supply from the facial and lingual arteries.supply from the facial and lingual arteries.
Innervation :Innervation :
Sympathetic - Cranial Cervical SympatheticSympathetic - Cranial Cervical Sympathetic
Ganglion(CCSG)Ganglion(CCSG)
Parasympathetic - Chorda Tympani of facialParasympathetic - Chorda Tympani of facial
nervenerve

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SUB LINGUAL GLAND:SUB LINGUAL GLAND:
It is the smallest of all the major salivary glandsIt is the smallest of all the major salivary glands
and is located beneath the mucous membrane ofand is located beneath the mucous membrane of
the floor of the mouth and above the mylohyoidthe floor of the mouth and above the mylohyoid
muscle.This gland lacks a distinct capsule.muscle.This gland lacks a distinct capsule.

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Compared with the Parotid and Sub mandibularCompared with the Parotid and Sub mandibular
glands,the Sub lingual gland is a collection ofglands,the Sub lingual gland is a collection of
small glands than a clearlysmall glands than a clearly
delineated one.delineated one.
sublingual glands secrete a salivasublingual glands secrete a saliva
that is predominantly mucousthat is predominantly mucous
in characterin character
The sublingual ductThe sublingual duct [[Bartholins ductBartholins duct]] maymay
join the Submandibular duct and open into thejoin the Submandibular duct and open into the
oral cavity with a separate sublingual papilla.oral cavity with a separate sublingual papilla.

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Blood supply:Blood supply:
It is from Sublingual and Sub mentalIt is from Sublingual and Sub mental
arteries.arteries.
InnervationInnervation --
Sympathetic- Cranial Cervical SympatheticSympathetic- Cranial Cervical Sympathetic
Ganglion (CCSG)Ganglion (CCSG)
Parasympathetic - Chorda Tympani of facialParasympathetic - Chorda Tympani of facial
nervenerve

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MINOR SALIVARY GLANDS:MINOR SALIVARY GLANDS:
The minor salivary glands are located beneath theThe minor salivary glands are located beneath the
epithelium in almost all parts of the oralepithelium in almost all parts of the oral
cavity.These glands usually consists of severalcavity.These glands usually consists of several
small groups of secretory units opening via shortsmall groups of secretory units opening via short
ducts directly into the mouth.ducts directly into the mouth.
They are mainly: Labial and Buccal glands.They are mainly: Labial and Buccal glands.
Glossopalatine glands.Glossopalatine glands.
Palatine glands.Palatine glands.
Lingual glandsLingual glands

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Labial & Buccal glands:Labial & Buccal glands:
The glands of the lip and cheeks classically haveThe glands of the lip and cheeks classically have
been described as mixed,consisting of mucousbeen described as mixed,consisting of mucous
tubules with serous demilunes.tubules with serous demilunes.
Glossopalatine Glands:Glossopalatine Glands:
These are pure mucous glands.They are localizedThese are pure mucous glands.They are localized
to the region of the isthmus in the Glossopalatineto the region of the isthmus in the Glossopalatine
fold.fold.
Palatine Glands:Palatine Glands:
These are also pure mucous glands.They consists ofThese are also pure mucous glands.They consists of
several hundred glandular aggregates in theseveral hundred glandular aggregates in the
lamina propria of the postero-lateral region of thelamina propria of the postero-lateral region of the
hard palate and in the submucosa of the soft palatehard palate and in the submucosa of the soft palate
and uvula.and uvula.

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Lingual glands:Lingual glands:
The Glands of tongue can be divided into severalThe Glands of tongue can be divided into several
groups.groups.
The anterior lingual glands are located near theThe anterior lingual glands are located near the
apex of the Tongue.These are mucous Glands.Theapex of the Tongue.These are mucous Glands.The
ducts open on the ventral surface of the tongueducts open on the ventral surface of the tongue
near the lingual frenum.near the lingual frenum.
The posterior lingual mucous Glands are locatedThe posterior lingual mucous Glands are located
lateral and posterior to the vallate papillae and islateral and posterior to the vallate papillae and is
associated with the lingual Tonsil.They are purelyassociated with the lingual Tonsil.They are purely
mucous in character,and their ducts open onto themucous in character,and their ducts open onto the
dorsal surface of the tongue.dorsal surface of the tongue.

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The posterior lingual serous Glands are LocatedThe posterior lingual serous Glands are Located
between the Muscle fibers of the Tongue below thebetween the Muscle fibers of the Tongue below the
vallate papillae.vallate papillae.
Their ducts open into the trough ofTheir ducts open into the trough of
vallate papillae.vallate papillae.

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SALIVA FLOW & VOLUME:
The exact volume and flow rates of individual gland
as also the whole saliva is difficult to determine.
The average given values for the volume of saliva
secreted per day varies between 750ml to 1lit.Under
tested conditions the flow rate is 0.3ml/min and may
increase up to 2.5-5.0ml on stimulation.
Saliva of about 1.0ml is present in mouth at any given
time and average volume required to initiate a
swallowing reflex is 1.1ml .
0.8ml of saliva remains after each swallow.

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Factors influencing salivary Flow
Unstimulated
• Degree of hydration
• Body position
• Exposure to light
• Previous stimulation
• Circadian rhythms
• Circannual rhythms
• Drugs

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• Stimulated
• Mechanical/gustatory
• Vomiting
• Smoking
• Gland size
• Gag reflex
• Olfaction
• Food intake

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Salivary flow rate:
• Exhibit diurnal and seasonal variations
• Peak : mid afternoon
spring
• Normal salivary flow rate:
0.3 ml/min(unstimulated)
1.5 -2 ml/min (stimulated)
During sleep flow is negligible.

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• Approximately 0.5litres of saliva is secreted per
day,of which 25%comes from submandibular
salivary glands and 66%from parotids.
• During sleep flow rate is negligible.

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Variations in salivary Flow
• Unstimulated flow
– Submandibular g. 70%
– Parotid g. 20%
– Accesory g. 7%
– Sublingual 2%
• Acid stimulation
– Parotid g. 45%
• Chewing
– Parotid g. 60%

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Control of secretion
The physiologic control of salivary gland
secretion is mediated through the activity of the auto
nervous system.
The release of neurotransmitters from the
vesicles in the nerve terminals adjacent to the
parenchymal cells stimulates them to discharge their
secretory granules and water and electrolytes. The
molecular events that occur is called ‘stimulus-
secretion coupling’

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• Norepinephrine interacts with both α-and β-
adrenergic receptors
• Acetylcholine interacts with the cholinergic receptor.
• Receptors for the peptide transmitter substance P are
also present on salivary glandcells
• Vasoactive intestinal polypeptide is present in nerve
endings in the salivary glands

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• After appropriate stimulation , it is thought that free
Ca2+ is released from a storage site within the
endoplasmic reticulum. Free cytoplasmic CaH
concentration can increase five- to tenfold in
seconds after such stimulation, which brings about
significant compensatory changes that include the
opening of two membrane ion channels for passage
of K+ and Cl-, with the chlorine channel confined to
the luminal surface of the cell and the potassium
channel to the basolateral surface.

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When potassium is released from the cell a
compensatory uptake of Na+ and Cl- occurs. The Cl
exits the cell through the channels at the luminal
surface;it is speculated that, to maintain electrical
neutrality, Na+ enters the lumen through the
paracellular pathway.The result of these ionic
relocations is a flux of water into the lumen via the
osmotic coupling of NaCl and H2O.

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Clinical Co-relations :

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Sjogren’s syndrome:
This is an autoimmune disease resulting in exocrine
gland dysfunction and characterized by the absence or
diminution of saliva.
The submandibular,Parotid,Palatal,and labial glands
are most frequently affected.
This syndrome is manifested by extensive lymphoid
infiltration and atrophy of the ductal,acinar and
myoepithelial cells.
Proliferation of lymphoepithelial elements results in
narrowing of the duct,with localized dilations
proximal to the zones of narrowing.

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Sialolithiasis:
Presence of stones in the salivary ducts is
known as sialolithiasis.These stones are most
commonly seen in wharton’s duct and less common in
stensen’s duct. When such stones are small. they may
have only a minor influence on gland function . Large
stones,however,may obstruct the duct and produce
large back pressures on the gland,which induces
destruction of the parenchyma.

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XEROSTOMIA:
It is also called as dry mouth. It may be due to
regressive changes in the salivary glands,
particularly atrophy of the cells lining the
intermediate ducts.
A decrease in salivary flow can also be the result
of illnesses like Diabetes Mellitus and insipidus,
Nephritis, Pernicious anemia,Administration of
certain medications like ephedrine,atropine,
phenothiazine,and Other conditions like x-ray
irradiation, old age and vitamin deficiencies.

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Use of artificial saliva and frequent mouth rinses
particularly during meals, may be helpful. Coating
the tissue surface of dentures with petroleum
lubricating jelly, silicone fluid can temporarily
increase denture retention and decrease irritation of
the underlying soft tissues.
Sialogogues ,drugs that stimulate the flow of saliva
without affecting the ptyalin content, can be tried if
glandular disfunction is still present.Pilocarpine
hydrochloride in 5-mg doses before meals will cause
a pronounced flow for two to five hours.

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If the decrease in salivary flow is due to nutritional
deficiencies,therapeutic dose of nicotinamide for a
period of up to two weeks can be used.
It may be necessary to limit denture use to short
period and restrict the diet to moist foods that are
soft or liquid.

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MUCOCELES:
These are retention cysts of the minor salivary
gland ducts and contain mucus.
These probably arise following irritation or
mechanical trauma to the salivary gland ducts,
which results in the rapture or destruction of the
duct.
SIALADENITIS:
The seepage of mucus into the surrounding
connective tissue due to mucoceles leads to
inflammation and the formation of granulation
tissue.

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PTYALISM:
Increased flow of saliva is called ptyalism.It
occurs due to stomatitis, teething, neurological
disturbances, increased gastric secretion.

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Prosthodontic considerations:

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EXCESS SALIVATION:
Excess salivation ,particularly by the sub
maxillary and sublingual glands, presents a
problem in impression making.
When this problem exists, atropine sulfate can be
administered orally prior to the impression
making.

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Excessive secretions of mucus from the palatal
glands may distort the impression material in
the posterior two thirds of the palate.
To counteract this problem,
1] Palate may be massaged to encourage the
glands to empty.
2] The mouth may be irrigated with an
astringent mouth wash just prior to inserting
impression material.
3] The palate may be wiped with gauze.

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DECREASED SALIVA:
The adhesive action of a thin film of saliva between
the denture base and the underlying soft tissues in
considered to be one of the principle factors in
denture retention.
The thin film of saliva also acts as a lubricant and
cushion between the denture base and the tissues
and tends to eliminate irritating friction.

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 A decrease in salivary flow will interfere with
denture retention as well as make mastication and
deglutition difficult.
 The mechanical protection of the denture-
supporting tissues by the saliva film will be lost,
predisposing them to irritation.
 The antibacterial action of the saliva will be
reduced proportionally to the decrease in salivary
flow.
 Artificial salivary substitutes and frequent mouth
rinses will be helpful.

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THICK ROPY SALIVA:
Thick mucous type of saliva alters the seat of the
denture, as it accumulate between the tissues and the
denture.
THIN WATERY SALIVA:
Thin serous saliva of high surface tension
is considered as ideal as it affords enough
retention.

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Role of saliva in complete denture
retention
Retention of maxillary complete dentures can be
affected by
physiological
physical
mechanical
surgical factors.

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Role of saliva:
Atmospheric pressure, or “suction” as it is
incorrectly called, contributes very little to the
retention of a denture until an attempt is made to
move it away from the tissue. Then, provided that
the saliva film remains intact, a reduction in
pressure occurs between denture and tissues and
atmospheric pressure resists displacement of the
denture. If the saliva film breaks down and air
enters he space between denture and tissues, the
denture is no longer retained. Hence it is important
to exclude as much air as possible from the saliva
film

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Viscosity and volume of saliva:
The relationship between the denture and the
tissues is a dynamic one. Whenever the denture tries
to move, the viscosity of the interposed saliva film
resist or dampens this movement.
Viscosity of the saliva depends upon its mucin
content. Parotid secretion is mainly serous and
therefore the secretion of the mandibular and the
sublingual glands is the more important for denture
retention.

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Mucin is also secreted from the palatal glands
and lies between denture and tissues, flowing slowly
to the periphery. Here it remains in the sulcus or on
the soft palate until it is swallowed.
A thin film of saliva resist flow much more
readily than a thicker film. Resistance to flow varies
inversely as the cube of the film thickness. Thus by
halving the gap between denture and tissue, the
retentive force due to resistance to saliva flow is
increased eightfold

m
If the saliva itself has a high viscosity, it resists
flow more effectively. Hence the use of denture
fixatives or adhesives produce a large increase in the
viscosity of saliva. Unfortunately with the forces
usually generated in the mouth, a saliva of such high
viscosity cannot be compressed to a thin film.
Therefore a marked increase in viscosity is necessary
to produce an effect similar to that of decreasing the
film thickness.
The danger of using denture adhesives is that a
thin film of saliva is developed initially, this
gradually increases in thickness and the patient finds
difficulty in reducing it down again to a narrow
section

m
Unless there is plenty of further
highly viscous saliva available in
the mouth, then as soon as the
denture is tilted or is moved away
from the tissues, there is a
shortage of saliva, air enters the
space, and the denture falls. This
is what usually happens when a
denture adhesive is in use as the
adhesive – thickened saliva
beyond the border of the denture is
swallowed and does not remain in
the mouth

m
If a denture is loaded at one side,
then the saliva film is thinned on
this side and the denture may
attempt to move away from the
tissues on the opposite side. Here
any extra saliva from the sulcus
can flow in and so maintain the
continuity of the saliva film in the
increasing space. Adequate saliva
volume is necessary and retention
is therefore poor in the mouths of
patients whose saliva volume is
low.

m
The rate at which displacement of
the denture is attempted is also
important. To a force applied
suddenly, there is little time for
saliva flow to occur and the
denture is displaced. If a much
smaller force is applied
continuously, however, flow takes
place and the denture remains in
place.

m
The physical factors are further divided into
Adhesion
Cohesion,
Interfacial surface tension and
Atmospheric pressure.
These physical factors operate in the fluid film
between the denture base and the mucosa.

m
Adhesion:
Adhesion is the physical force involved in the
attraction between unlike molecules. A drop of
water introduced on the surface of a solid glass plate
will resist movement away from the glass in
proportion to the adhesion between the unlike
materials.
Adhesion of salvia to the mucous membrane
and the denture base is achieved through ionic
forces between charged salivary glycoprotein and
surface epithelium or acrylic resin. By promoting
the contact of saliva to both oral tissue and dentures
base, adhesion works to enhance further the
retentive force of interfacial surface tension.

m
Cohesion:
Cohesion is the physical attraction of like molecules
for each other. It is a retentive force because it occurs
within the layer of fluid (saliva) that is present
between the denture base and the mucosa, and works
to maintain the integrity of the interposed fluid. The
property of cohesion is effective in direct proportion
to the area covered by the denture, if other factors are
equal.
According to Jacobson and Krol, cohesion is a
physical factor of electromagnetic force acting
between the molecules of the same material. A
molecule within a fluid has an attraction exerted on it
on all sides by neighboring molecules

m
Forces of cohesion are responsible for
maintaining the continuity of a water droplet when
placed in contact with another material. Normal
saliva is not very cohesive, so that most of the
retentive force of the denture – mucosa interface
comes from adhesive and interfacial factors unless
the interposed saliva is modified (as it an be with
the use of denture adhesive).

m
Interfacial force:
It is the resistance to separation
of two parallel surfaces that is
imparted by a film of liquid
between them. A discussion of
interfacial forces is best broken
into separate comments on
interfacial surface tension and
viscous tension.

m
Interfacial surface tension:
It is defined as the force that maintains the surface
continuity of a fluid. It results from a thin layer of
fluid that is present between two parallel planes of
rigid material. It is dependent on the ability of the
fluid to “wet” the rigid surrounding material. The
cohesive attraction between molecules is balanced in
equilibrium within the fluid. At the surface, the
absence of the neighboring molecules creates the
one sided attraction imbalance that causes surface
tension. If the surrounding material has low surface
tension, as oral mucosa does, fluid will maximize its
contact with the material, thereby wetting it readily
and spreading out in a thin film.

m
If the material, with the result that it will form
beads on the material’s surface. Most denture base materials
have higher surface tension than oral mucosa, but once
coated by salivary pellicle they display low surface tension
that promotes maximizing the surface area between liquid
and base. The thin fluid film between denture base and the
mucosa of the basal seat therefore furnishes a retentive force
by virtue of the tendency of fluid to maximize its contact
with both surfaces. It is a relatively small force when
considered alone but by interaction with other physical
factors, it becomes an important determinant.

m
Another method to explain the role of
surface tension in denture retention is by describing
capillary attraction or capillarity. Capillarity is what
cause a liquid to rise in a capillary tube, because in
this physical setting the liquid will maximize its
contact with the walls of the capillary tube, thereby
rising along the tube wall at the interface between
liquid and air. When the adaptation of the denture
base to the mucosa on which it rests is sufficiently
close, the space filled with a thin film of saliva acts
like a capillary tube in that the liquid seeks to
increase its contact with both the denture and the
mucosal surface. In this way, capillarity will help to
retain the denture.

m
Interfacial surface tension may not play as important
a role in retaining the mandibular denture as it does
for the maxillary one. Interfacial surface tension is
dependent on the existence of a liquid / air interface
at the terminus of the liquid/ solid contact; if the two
plates with interposed fluid are immersed in the same
fluid, there will be no resistance to pulling them
apart. In many patients, there is sufficient saliva to
keep the external borders of the mandible denture
awash in saliva, thereby eliminating the effect of
interfacial surface tension. This is not so in the
maxilla. A simple system to explain interfacial
surface tension involves the attraction of two glass
slabs placed in direct apposition with an interposed
fluid film. In 1948, Stanitz27 used this model to
explain the part played by the fluid film in denture
retention

m
In review, the phenomenon of surface tension is
defined as the force that maintains the surface
continuity of a fluid. This results from the imbalance
in cohesive forces between molecules present at the
surface. The cohesive attraction between molecules
is balanced in equilibrium within the fluid. At the
surface the absence of neighbouring molecules
creates the one-sided attraction and imbalance that
causes a free potential energy called surface tension.

m
The surface tension plays a role in the fixation has
already been stressed by various authors, including
Schultz (1921), who formulated the equation.
K = 2 a X y
b
Where
K = fixation force
a = surface tension coefficient
y = surface of the plates
b = distance between the plates

m
Interfacial viscous tension:
It refers to the force holding two
parallel plates together that is
due to the viscosity of the
interposed liquid.

m
Atmospheric pressure:
Atmospheric pressure is the physical factor of
hydrostatic pressure due to the weight of the
atmosphere on the earth’s surface. At seal level this
force amounts to 14.7 psi.
Atmospheric pressure can act to resist dislodging
forces applied to dentures, if the dentures have an
effective seal around their borders. This resistance
force has been called “suction” because it is a
resistance to the removal of dentures from their basal
seat; but there is no suction or negative pressure,
except when another force is applied (suction alone
applied to the soft tissues of the oral cavity for even a
short time would cause serious damage to the health
of the soft tissues under negative pressure

m
For example, a suction cup pressed against a
pane of glass stays in place because the rubber of
the squeezed cup elastically seeks to return to a
larger shape, thereby causing air pressure within the
cup to be less than the pressure outside the cup. A
denture cannot be distorted like a suction cup, but
oral mucosa can be.
When a force is exerted perpendicular to
and away from the basal seat of a properly extended
and fully seated denture, pressure between the
prosthesis and the basal tissues drops below the
ambient pressure, resisting displacement.

m
Retention due to atmospheric pressure is
directly proportional to the area covered by the
denture base. For atmospheric pressure to be
effective, the denture must have a perfect seal
around its entire border. Proper border molding with
physiological, selective pressure techniques is
essential for taking advantage of this retentive
mechanism.

m
The mode of action of Denture Adhesives depend
on both physical and chemical factors of material.
The adhesives tend to swell from 50-150% by
volume in the presence of water, this results in
formation of anions that are attracted to cationic
proteins in the mucus membrane.

m
Summary and Conclusion
Saliva is the glandular secretion which
constantly bathes the teeth and the oral mucosa.
The presence of saliva is vital to the
maintenance of healthy oral tissues. Severe
reduction of salivary output not only results in
a rapid deterioration in oral health but also has
a detrimental impact on quality of life.

m
REFERENCES
 Bhaskar,S.N.: Orban’s Oral Histology and
Embryology, ed. 10, St .Louis,1990, The C.V.
Mosby Co.
 Sheldon Winkler.: Essentials of complete denture
Prosthodontics, ed. 2, 2004
 Martin s. Greenberg & Michael Glick. Burket’s
oral Medicine Diagnosis and Treatment.
(2003);10th
ed,Elsevier India.
 Arther c Guyton, John E Hall. Text Book of
Medical physiology, (2001)10th.
Ed. W.B.
Saunders company.
 James W.Little, Donald A.Falace, Craig S.Miller.:
Dental Management Of Medically Compromised
Patient, ed. 6,2002

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