Saliva1

SALIVA
Saliva is not one of the popular bodily fluids. It lacks the drama of
blood, the sincerity of sweat and the emotional appeal of tears. Despite the
absence of charisma, however it is becoming increasingly apparent to
investigators and clinicians in a variety of disciplines that saliva has many
diagnostic uses and is especially valuable is the young, the old and infirm.
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 paratid, sublingual, submandibular
salivary glands and the mucous glands of oral cavity.
Digestive juices
There are five digestive juices in all namely Saliva, gastric juice pancreatic
juice, succus entericus (intestinal juice) bile.
The necessity for so many digestive juices is that.
1) one juice does not contain all the enzymes necessary for digesting all the
different types of food stuffs.
E.g. Saliva contains only carbohydrate splitting enzymes. Gastric
juice contains both fat and protein splitting enzymes but none acting on
carbohydrates.
2) one particular juice cannot digest a particular type of food up to
completion.
Composition and function :
Human saliva
 Total amount : - 1,200 – 1500 ml in 24 hrs. A large proportion of this
24 vol is secreted at meal time when the secretory rate is highest.

 Consistency – slightly cloudy because of the presence of cells and
mucin.
 Reaction – usually slightly acidic (PH 6.02 – 7.05). on standing or
boiling it loses CO2 and becomes alkaline. This alkaline reaction
causes precipitation of salivary constituents, as tartar on the teeth or
calculus in salivary ducts.
 Specific gravity – 1.002 –1.02.
 Freezing point – 0.07 – 0.340
C
Composition
99.6% Water & 0.5% Solids.
1. Cellular constituents – Yeast cells, bacteria, protozoa,
polymorphonucler leucocytes, desquamated epithelial cells etc.
2. Inorganic salts – About 0.2% consists of NaCl, KCl, acid & Alkaline
sodium phosphate, CaCO3, Calcium phosphate, K thiocyanate.
(Smoker’s Saliva rich in thiocyanate)
3. Organic 0.3%
a) Enzymes – Ptyaline (salivary amylase) lipase, carbonic
anhydrase, phosphatase and a bacteriolytic enzyme, lysozome.
b) Mucin.
c) Urea, Amino acids, cholestrol and vitamins.
d) Soluble specific blood group substances. A, B, O – 10 to 20
mgm / lit.
4. Gases – 1ml of oxygen, 2.5 ml nitrogen and 50 ml of CO2 per 100
ml.
Bicarbonates, phosphates and the proteins act as buffers. An enzyme
kallikrein is present in saliva which acts upon plasma protein to produce a
substance known as Kallidin or brady kinin. This produces vasodilation of
salivary gland during secretion.

FUNCTIONS
I Mechanical function
1. It keep the mouth moist & helps speech
2. It helps in the process of mastication of the food stuff and in
preparing it into a bolus, suitable for deglutination. Here saliva also
acts as a lubricant.
3. It dilutes hot and irritant substances and thus prevents injury to
OMM.
4. Constant flow of saliva washes down the food debris and thereby
does not allow the bacteria to grow.
The mechanical functions of saliva are its chief functions and is
mainly contributed by mucin.
II Digestive function :
Saliva contains 2 enzymes.
a) Ptyalin – which splits starch upto maltose .
b) Maltose – (in traces ) converts maltose into glucose.
III Excretory functions :
Saliva excretes urea, heavy metals, thiocyanates, certain drugs like
iodide etc. alkaloids, such as morphine, antibiotics, such as pernicillin,
streptomycin etc.
IV Helps in the sensation of taste – Taste is a chemical sensation. Unless
the substances be in solution, the taste buds cannot be stimulated. Saliva
acts as a solvent and is thus essential for taste.
V Helps water balance – Saliva keeps the mouth moist. When moisture is
reduced in the mouth, certain nerve endings at the back of the tongue are
stimulated and the sensation of thirst arises.
VI Helps heat loss – This is mainly found in animals. When they become
hot and excited more saliva is secreted causing greater heat loss.

VII Buffering action – Mainly bicarbonate and to a lesser extent phosphate
and mucin present in saliva act as buffers.
VIII Bacteriolytic action - Cell membrane of different varieties of bacteria
contains polysaccharides, lyzozoyme, the enzyme present in the saliva is
poly saccharidise, thus it dissolves the cell wall of many bacteria and finally
kills them.

DEVELOPMENT OF THE SALIVARY GLANDS
The 3 major sets of salivary gland – the parotid, the submandibular,
and the sublingual – originate in a uniform manner by oral ectodermal
epithelial buds invading the underlying mesenchyma.
The parotid gland buds are the first to appear at the 6th
week intra
uterin on the inner cheek near the angles of the mouth, and grow back
towards the ear. In the “par-otid, or ear region, the epithelial cord of cells
branches and canalizes to provide the acini and ducts of the gland. The duct
and acinar system is embedded in a mesenchymal stroma that is organized,
into lobules and becomes encapsulated. The parotid duct, although
repositioned traces the path of the embryonic epithelial cord in the adult.
The submandibular salivary gland buds also appear in the 6th
week as
a grouped series forming epeithelial ridges on either side of the midline in
the floor of the mouth. The epithelial cord proliferates back into the
mesenchyme beneath the developing mandible, to branch and canalize,
forming the acini and duct of the submandibular gland. The mesenchymal
stroma separates off the parenchymal lobules, and provides the capsule of
the gland.
The sublingual glands arise in the 8th
week intra uterine, as a series of
about ten epithelial buds just lateral to the submandibular gland anagen.
These branch and canalize to provide a number of ducts opening
independently beneath the tongue.
A great number of smaller salivary glands arise from the oral
ectodermal and endodermal epithelium, and remain as discrete acini and
ducts scattered throughout the mouth.
“ Some of the major salivary glands building from the oral cavity”

SALIVARY CONTROL
AFFERENT PATHWAYS
The rate of salivary gland secretion may be affected by 3 principal
factors.
a) Local factors – Whenever the sensation of taste is stimulated, the
salivary flow rate increases. The fibres carrying taste sensation pass
along the chorda tympani in the lingual nerve and the
glosopharyngeal nerve. Glassophyryngeal nerve stimulation results
mainly in increase parotid salivary flow. Acid stimuli are the most
effective salivary flow stimulants, salt and sweet less so, and bitter
the least effective.
Olfactory irritants similarly cause increase salivary flow. There is
however, uncertainty as to whether non-irritating olfactory stimuli
also have a similar effect or whether the salivary response is a
conditioned reflex.
Irritation of the oral mucosa can also result in increased salivation,
this feature is most pronounced following new denture on orthodontic
appliance insertion.
b) Emotional (psydric) stimuli – The sight of food, taking about food, on
the noise of food preparation are sufficient to activate the conditioned
reflexes leading to increase salivation. Sight, thought or discussion of
disliked food – decrease salivation.
c) Stimulation from other organs - Oesophageal irritation causes reflex
salivation, although gastric irritation leads to increase salivation as a
component of the nausea / vomiting reflex.
CENTRAL CONTROL
The afferent stimuli are finally integrated in the cell bodies of
preganglionic secretomotor neurons. The cell bodies of the sympathetic
nerous system appear to lie in the lateral columns of the first five thoracic

nerves, with the spinal reflex centers being influence by the medulla and
higher centers eg. Hypothalamus. This area, the nucleus salivations,
comprise a neuronal cluster in the reticular formation extending from the
facial nucleus to the nucleus ambigues.
Nucleus salivations
1) Nucleus salivatorius superior –
stimulation causes secretion from the
ipsilateral subsmandibular gland
2) Nucleus salivatorius inferior –
stimulation causes secretion from the
ipsilateral parotid gland.
EFFERENT PATHWAY
The control of salivation is mainly under parasympathetic control,
although there may be a sympathetic component.
Passing through the facial nerve, parasympathetic fibres pass via the
chorda tympani to reach the lingual nerve and then, synapsing in the small
ganglia around the submandibular and sublingual nerves, short post-
ganglionic fibres pass into the glands.
The glossopharyngeal fibres pass through the tympanic and lesser
superficial petrosal nerves to reach the otic ganglion where they synapse
with the post ganglionic fibres of the auriculotemporal nerve which supplies
the parotid gland.
AUTONOMIC CONTROL
The sympathetic fibres synapse in the superior cervical ganglion with
postganglionic fibres then passing to all the salivary glands.
The parasympathetic post ganglionic neurotransmitter is
acetylcholine, whereas that of the sympathetic postganglionic terminals is
nonepinephrine (noradrenaline), in addition to salivary secretion, the
Autonomic Nervous System also exerts control even the glandular
vasculature, excretory duct activity and myoepithelial cells.

FUNCTIONS OF SALIVA
1) DIGESTIVE FUNCTION
The only important digestive enzyme present in saliva is PTYALIN
(or salivary amylase) it digests starch provided it has been previously
cooled.
It is clear that food remains in the mouth for too a short time to allow
much digestion of starch to occur. However after a large meal, the PH of the
food which enters the stomach last remains nearly 30 mins or more, during
which amylase activity may continue. Once the gastric HCl soaks into the
food and lowers the PH amylase is activated and is eventually digested by
pepsin, like any other protein.
It is possible that the main action of salivary amylase is to digest
starch from food residues which remain in the mouth after meals, rather than
to contribute to digestion as a whole.
2) ANTIBACTERIAL FUNCTION OF SALIVA
Although bacteria are always present, wounds in the mouth rarely
become infected. This fact suggests that saliva contains some means of
keeping in cheek harmful bacteria and that the organisms normally present
in the mouth are those which have become resistant to salivary inhibition.
Dog saliva inhibits many bacteria more powerfully than does human,
hence dogs are free from dental caries.
Saliva has some mechanical action in removing bacteria form the
mouth and converting them to the stomach where most of them are killed
and digested by gastric juice. Although bacterial growth on some surfaces of
the mouth is greatly restricted by this means, it probably has little effect on
the bacteria in sheltered places such as the crevices between the teeth.
a) LEUCOTAIN & OPSONINS
Two properties of saliva have been described which may be related to
its antibacterial power.

1) Saliva increases capillary permeability
2) Mixed saliva possesses leucotaclic activity i.e. the power of attracting
polymorphonuclear leucocytes, but this is absent from the saliva
collected from the ducts and is greatly reduced after thorough
brushing of the teeth and the dorsum of the tongue. The activity
returns within 1-3 hrs in different individuals. Whether the leucotoxin
in saliva play any part in the normal supply of leucocyes in the mouth
is not known, but if the tissues are injured it would gain access to the
damaged area and by its dual action may promote the accumulation of
leucocytes.
The substances in plasma which make bacteria more palatable to
leucocytes are called opsonins now thought to be IgG. IgM and
certain constituents of complement saliva contains opsonins, but
being Ig, they are much less active than in plasma, saliva from caries
– free individuals has been stated to show more opsonic activity than
caries – active saliva.
b) THE NATURE OF THE ANTIBACTERIAL SUBSTANCES IN
SALIVA.
In the year 1922 Flemming discovered in tears, nasal secretion,
saliva, eggwhite and in most tissues and body fluids a substance which
dramatically kills and dissolves some strain of organisms.
The substance is called lysozyme on muranidase, an enzyme which
splits a link present in the walls of certain bacteria, the splitting of which
causes their death and disintegration.
The effectiveness of lysozyme in saliva is probably reduced by the
presence of mucin which inhibits its action.
C) BACTERIAL ANTAGONISMS
Some organisms are unable to survive in the mouth because they are
killed in the presence of other salivary organisms.

Effect demonstrated by pouring a suspension in agar of one species of
organisms over previously grown colonies of other organisms killed by UV
light on further incubations those organism may fail to grow in the vicinity
of the dead colonies.
Unidentified factors, H2O2 and lactic acid are products of salivary
bacteria which antagonizes other species in the oral flora.
D) SALIVA & BLOOD COAGULATION
When freshly – shed blood is diluted with saliva its clotting time is
reduced.
This property of saliva has been studied quantitatively by Soku
(1960) whose main finding were as follows
i) If blood is diluted with saline, the clotting time is reduced to about
40% of normal but when diluted with saliva it is reduced to 10% of
normal the effect being similar whether the blood saliva ratio was 4:1
or 1:1
ii) Saliva from all 3 glands as well as both supernatant and sedement
from whole saliva all contained the coagulation factors normally
present in serum.
iii)Whole saliva contains factors which act like tissue thromboplastine
iv) Whole saliva could replace the platelet factor in experimental clotting
but parotid r submandibular saliva could only do so partially.
v) Saliva as secreted from the ducts dose not contain factor V but whole
saliva and its sediments did contain some of the factor
3. BUFFERING POWER OF SALIVA
4. SALIVA AS A LUBRICANT
Glycoproteins – main protein of saliva. Have the important property
of giving saliva its slimy nature. The moistening of the food is important for
bolus formation and its lubrication of mouth is necessary for clean speech.
Accurate positioning of the tongue in relation to teeth is difficult when the

mouth is dry. These glycoproteins are at high concentrations in the minor
mucous gland and sublingual gland secretions, intermediate in
submandibular and very low in parotid.
The lubricating function of saliva is perhaps best appreciated when
salivary flow is inhibited during nervousness or embracement.
5. SALIVA AND WATER BALANCE
Common (1937) first observed that the drying of the month due to
excessive evaporation of saliva, as during prolonged talking, acted as a
stimulus to salivary flow, the “dry mouth reflex” and its existence has been
thoroughly confirmed. One of the theories of nature of thirst is that it
results from drying of the mucous membrane in the pharynx . If the mouth
is dry, and dry mouth reflex operates salivary flow is stimulated which
prevents drying of the pharynx and according to this theory thirst is avoided
if the body tissues are short of water, the reflex does not occur and in these
circumstances thirst follows any drying.
6. SALIVA AND TASTE
The sensation of taste is produced only by substances in solution.
Some foods, such as fruits, contain such a high proportion of H2O that
probably all the substances which have a taste are already in solution and
their taste may be received as soon as they are released by mastication.
Other foods, biscuits for eg. Contain relatively little water and before their
taste becomes apparent saliva must dissolve out the favorite constituents. By
this means saliva not only makes eating more pleasurable but may assist in
the detection of unwholesome contaminants of food.
7. SALIVA AS A ROUTE OF EXCRETION
It is frequently stated that the saliva is a solute by which certain
substances are excreted. It seems doubtful whether this can apply to any of
the normal constituents of saliva since they would be absorbed from the
intestine after the saliva was swallowed. Saliva can only be an effective

route of excretion for substances that are either destroyed or rendered
insoluble during their passing through the gut after swallowing, for eg. The
mercury and lead are present in traces in the saliva of people suffering from
poisoning by these. However the amount of excretion through the saliva
would seem to be insignificant compared with that via the kidney.
8. Reported functions of uncertain status.
a) The nerve growth factor.
b) Epidermal growth factor.
c) Parotin, a harmone – like subs isolated from the parotid gland.
d) Iodine metabolism.
THE EFFECTS OF REMOVAL OR INACTIVITY OF SALIVARY
GLANDS :
Experiments conducted on rats where in the salivary glands removed
exhibited a most striking feature i.e. there was an increase in the member of
bacteria in the mouth and the incidence of dental caries.
In one experiment, all 3 pairs of salivary glands were removed, dental
caries increased almost 3 times in rats.
Other effects – servere recession of the gingivae around the anterior
teeth resulting in exposure of cementum, which occurs in 14-18 days from
the removal of the glands.
Exposed cementum became carious and debris accumulated which
caused ulceration of the soft tissue and resorption of the alveolar bone.

THE EFFECT OF DESALIVATION OF OTHER ORGANS.
Removal of salivary glands
Salivary flow
Intake of food
Fall in body weight especially in the
Units of adrenals, testis, ovary & uterus.
11. SATURATION
As previously mentioned, saliva is supersaturated with respect to
tooth mineral. This is responsible for the growth of hydroxyapatite crystals
during the remineralisation phase of the caries process. If it were not for this
situation, the teeth would slowly dissolve in saliva.
In addition, salivary calcium and phosphate are the source of minerals
for calculus formation. The presence in saliva of inhibitors of precipitation
such as statherin and the proline rich protein is presumably a major factor
preventing excessive calcification in the mouth. However in plaque, where
these proteins cannot penetrate among the their relatively large molecular
size, they are unable to prevent seeding and growth of calcium phosphate
crystals, and hence calculus formation.
MAINTAINING TOOTH INTEGRITY
Saliva maintains the tooth integrity by demineralization and
remineralization process. Demineralization occurs when acid diffuses
through the plaque and the pellicle into the liquid phase of enamel between
enamel crystals, resulting in crystalline dissolution which occurs at a
pH of 5-5.5, a critical PH range for the development of caries. Dissolved
mineral subsequently diffuses out of the tooth. The buffering capacity of
saliva greatly influences the Ph of plaque surrounding the enamel, thereby
inhibiting caries progression. Remineralization is the process of replacing

lost mineral through the organic matrix of the enamel to crystal.
Supersaturation of minerals in saliva is critical to this process.
The high salivary concentration of the Ca and PO4 which are
maintained by salivary protein may recount for the maturation and
remineralization of enamel. Salivary peptide contribute to the stabilization
of Ca & PO4 salt solution, serves as lubricant to protect tooth from wear and
may initiate the formation of protective pellicle by binding to
hydroxyapatite. Presence of F in saliva speed up the crystal precipitation by
forming fluorapatite viz like coating more resistant to caries.

III. HALITOSIS (Factor aris, bad breath)
This is a condition which is almost universal if the, odor of breath on
waking is included and it increases the intervals between meals and is
reduced by eating, it tends to increase with advancing age.
Unpleasant Odors arise from
- Alimentary canal
- Lungs
- Bacterial activity
Main factors producing mouth odors are
1. Stagnation of food debris or epithelial cells which may arise from
reduced salivary flow or reduced friction in the mouth.
2. Tissue destructions as in periodontal disease or caries.
3. The smell of certain foods such as garlic cling to the mouth.
Saliva it self readily gives rise to bad odor especially during mouth –
breathing, prolonged talking or hunger.
Eating reduces halitosis partly because of increase salivary flow and
friction in the mouth, with the effect of removing the sources of odor and
possibly because if the food contains carbohydrates the growth of acid
producing bacteria is encouraged and bacteria which metabolize proteins
and its derivates are suppressed because they cannot complete for the
limited growth factors in saliva.
Analysis of mouth air by gas chromatography showed that H2S and
methyl mercaptan were responsible for approx 90% of the odor, a 3rd
minor
constituent being dimethyl sulphide.
PREVENTION OF HALITOSIS
1. Mouthwash
2. Frequent drinks and means of stimulating saliva
3. Oxidizing agents.

PROPERTIES OF SALIVA
1) Viscosity and spinnbarkeit.
Saliva is a viscous fluid and also show the property of spinnbarkeit
which is the ability to be drawn out into long elastic threads.
Cause of the viscosity of so dilute a solution as saliva is not
understood. Gotts cholk (1961) suggested that the mutual repulsion of the
highly ionized salt groups at the end of the side chains of glycoproteins
would tend to keep the polypeptide core treeched and the molecule
elongated. Molecules of this shape make their solutions viscous by the
considerable friction incurred in the movement relative to one another.
Considerable doubt, however.
Sialate contents of human parotid and submandibular saliva are
similar where as their viscosities are very different.
Schrager and Dates (1971) showed that the side chains and in
sulphate groups which might perform the role originally suggested for
sealate. Large numbers of water molecules become attached to the
glycoproteins and the great bulk of these hydrated molecules may contribute
to the viscosity of saliva, an effect not dependent on highly charged side –
chains.
2) Buffering power of saliva
Its buffering power will vary at different PH values because different
systems of buffers are effective over different parts of the PH range.
Salivary buffer consist of bicarbonates, phosphates and proteins.
Study by Letenthal in 1955 – measured the buffering power of saliva
before and after the removal of bicarbonate by a current of CO2 free air at
PH 5 and before and after dialysis, which removed both phosphates and
bicarbonate but which does not remove the large proteins.
Removal of bicarbonate greatly reduced the buffering power and
dialysis removed the whole of it. He concluded that bicarbonate is the most

important buffers, that phosphate plays some part but that, contrary to
previous views, the proteins can be disregarded as buffers in saliva over the
physiological PH. range , but are the chief buffers of Plaque. Buffers work
by converting any highly ionized acid or alkali which is tending to alter the
Ph of a solution, into a more weakly ionized substance. Bicarbonates release
the weak carbonic acid when an acid is added and once this acid is rapidly
decomposed into H2O & CO2, which leaves the solution, the result is not the
accumulation to a weaker acid (as with most buffers) but the complete
removal of acid. Bicarbonates are very effective buffers against acid and are
important in reducing PH changes in plaque after meals. Unstimulated
saliva which has much lower bicarbonate content, is a less powerful buffer
near neutrality.
Ericssion (1959) studied the diurnal variation in buffering power of
saliva in five subjects. He found that 1) it was high immediately on rising in
the morning but rapidly fell 2) it increases about a quarter of an hour after
meals but usually fell within half to 1 hour after meals. 3) there was an
upward tread in the buffering power through out the day, until wening when
it usually tended to fall.
3) Reducing power of saliva
In any complex biological systems viz saliva with its terming flora,
some chemical reactions in progress will be oxidations and others
reductions. The algebraic sum of these reactions is such that mixed saliva
normally has reducing properties.
In addition to bacterial reductions, saliva contains a complex mix of
substances with reducing properties which have been mistakenly resumed in
the past to be glucose. These reducing substance are present in saliva
collected from the ducts as well as in mouth saliva. They include
carbohydrate split off from glycoproteins, nitrites and some unidentified
subs of low molecular weight.

SALIVARY FLUORIDE
The role of saliva in the mode of action is now well recognized.
Fluoride may reach saliva directly from ingestion or from topical
application treatment, or indirectly from the blood stream via the salivary
glands or gingival – crevicular fluid, or from temporary intra-oral reservoirs
of fluoride, including surface deposition on the teeth of cal- fluoride like
material. It is often stated that it is the persistent elevation of salivary
fluoride from baseline values around 1µ mol/L to perhaps 2-5µ mol/L which
is true therapeutic factor in caries prevention. It is possible that equilibration
between salivary and plaque fluoride are important in modulating the
cariostatic actions of fluoride. Recent findings by Edgar et al, 1992 shows
that elevations in salivary fluoride of the order stated above are achieved
with the use of 1500 ppm – fluoride dentrifice or in areas with optimally
fluoridated water, these effects were seen more consistently than parallel
elevations in plaque fluoride. Clinical trials and a in situ model data (Dodds
and Edgar 1991) indicate that remineralization by fluoride is not
significantly affected by the presence or absence of plaque.
However since plaque must be present for demineralization to occur,
the accumultion of fluoride in plaque may be more significant in reducing
mineral loss than in enhancing mineral gain.
SALIVARY FLOW
2 types of saliva to be taken into consideration – stimulated
- unstimulated
Resting flow
Under resting conditions, without the exogenous stimulation also with
feeding, there is a slow flow of saliva, which keeps the mouth moist and
lubricates the mucous membranes. This unstimulated flow, which is present
majority of times, is very important for the health and well being of the oral

cavity. The unstimulated flow rates varies considerably during the day, and
is influenced by a number of factors.
Factors influencing unstimulated flow rate
1. Circadian variatjion
unstimulated flow peaks at approx 5 pm is most individuals.
Minimum flow during the might
This variation is independent of eating and sleeping behavior.
2. Light and arousal
If one is blend folded, or in an unlit room, the unstimulated flow rate
falls. This is also probably with the effect of visual input in maintaining a
state of arousal.
Saliva flow is much decreased during sleep.
3. Hydration
A loss of 8% of body water results in a cessation of saliva flow. This
resultant drying of the oral cavity is a feature of thirst. Although thirst and
H2O intake are under hypothalamic control and not dependent upon oral
dryness.
4. Exercise and stress :
A dry mouth is a future of the ‘fight and flight’ response. This is
probably not a direct action of the symptathetic supply to the gland, but
rather is due to inhibitory influence on the salivary nuclei arising from the
hypothalamus.
PSYCHIC FLOW (Stimulated)
A mouth watering sensation is a universal experience on the
anticipation on sight of food, especially if temptingly presented when
hungry. However, although the sensation is sudden flow of saliva into the
mouth, it has not provide possible to demonstrate a large increase in flow
rate in man arising from such a psychic stimuli. This is in contrast to the
well – established conditioned reflex effect in dogs, first demonstrated by

Pavlov, who did that the animals learned to associate the chewing of church
bells with meal times and would salivate on hearing the bells, even if food
was withheld. In man, a small increase in flow can usually be demonstrated
on thinking about food, or seeing it being prepared, but this does not
correspond in amount with the sensation of mouth watering. It has been
suggested that the latter is due to a sudden awareness of saliva already
present in the mouth or a momentary contraction of myoepithelial elements
to express ready – formed saliva into the mouth with out increasing the
overall amount of saliva formed.
Factors affecting flow.
UNCONDITIONAL REFLEXES
The most important stimuli to salivation are those associated with
feeding masticatory movement and especially taste.
Mastication
Chewing of flavourless bolus such as wax or chewing gum base leads
to an increase in saliva flow of about 3 folds. This is a reflex response
receptors in the muscles of mastication, TML, and mucosae detect the
presence of a bolus and its mastication, and stimulate the salivary nuclei to
increase the parasympathetic secretomotor discharge.
Gastatory stimuli :
The reflex effects of taste stimuli are more dramatic giving rise to
perhaps a ten – fold increase in saliva flow. Some stimuli are most effective,
followed by sweet, salt and bitter. Most foods also elicit olfactory stimuli
and a reflex response to smell can be demonstrated.
Other stimuli
The inhibitory action of stress on the salivary nuclei has already been
mentioned. On the other hand, there appear to be connections between the
salivary nuclei and the vomiting centre in the medulla, since copious reflex
salivation as well as nausea frequently occur first before vomiting perhaps

as an attempt to dilute or neutralize the irritant which is giving rise to the
nausea.
Hypersalivation (PTY slims) is also described in pregnancy, but the
physiological basis is nuclear, perhaps it seems from morning sickness, or
oesophageal irritation following reflex of gastric contents due to raised
abdominal pressure in late pregnancy. Complaints of excess salivation other
than under the above circumstances are usually associated with motor
disturbances of the oseofacial musculature, and are rarely substantiated by
measurement of flow rates.
POTENTIALLY ANTI – CARIES ACTIONS OF SALIVA
Anticaries effects of saliva can be categorized as
STATIC DYNAMIC
Static effect – are those which may be assumed to be exerted continuously
throughout the day, and include effects on the bacterial composition of
plaque through antibacterial or metabolic factors, protective effects of
pellicle formation, and effects of salivary contents (including F) in
maintaining a supersaturated environment for the tooth mineral.
Dynamic effect – on the other hand, are those which are mobilized over the
time – cause of the Stephen curve. These include the clearance of the
carbohydrate collagen and of the acid products of plaque metabolism, and
the alkalinity and buffering power to restore plaque Ph towards neutrality.
STATIC : 1. Anti bacterial – lysozyme, lactoferin, Ig, Sialoperoxidase
2. Supersaturation – Ca, PO4, OH, F statherin, Proline – rich peptides.
3. Substrates for plaque – sialin, urea, mucous glycoproteins.
4. Pellicle formation – low and high pressure peptides
DINAMIC
1. Buffering power – Bicarbonate ( increases on stimulation)
2. Clearance of sugar, acids – H2O (increases on stimulation)
3. Supersaturation – HCO3 (Alkalinity)

XEROSTOMIA (Dry mouth syndrome)
Xerostomia is a subjective feeling of oral dryness. It is generally
accompanied by salivary gland hypofunction and severe reduction in
secretion of whole saliva.
Oral manifestation
1. Saliva – decreases amount foamy, viscous and ropy.
2. Mucous membrane – appears dry, atrophic influenced and pale or
transluscent. Atrophy of the papilla of tongue.
Inflammation, fissuring, cracking and denudation of the tongue.
Soreness, during, and pain of OMM.
3. Salivary gland – pain and swelling may be present.
Patient suffers from a severe thrust.
Frequent ingestion of fluids
4. Lips – dry and cracked
5. Mastication – difficulty while eating
Material alba accumulates due to lack of self cleansing.
6. Swallowing – difficulty in swallowing
Dysphagia
7. Speech – difficulty in speech and phoneties
Dysphonia
Taste – taste cannot be appreciated
Dysgensia
Systemic Manifestations
- Throat – xerostomia causes dryness, hoarsness and persistent dry
cough
- Nose – dryness of nasal mucous leads to – burning , pain and
inflammation.
- Eyes – Causes, dryness, burning, itching, feeling that eyelids stick
together, blurred vision, sensitivity to light.

- Skin – Dryness and butterfly rashes
- Joints – Pain, swelling and stiffness of the joints.
- GIT = Constipation.
General symptoms
Fatigue, weakness, generalized body ache, weight lose, depression.
Etiology of xerostomia
1. Emotional reaction
2. Blockage of duct by calculus (salivary calculi)
3. Acute or chronic infection of salivary glands.
4. Drugs like atropine, antihistamines.
5. Aplasia
6. Agenesis
7. X – rays
8. Vitamin A, B, Riboflavin, Nicotinic acid diffusion.
9. Sjrons syndrome
10. Pernicious anemia, loss of fluid thru haemorrhaege excessive
sweating, diarhrroea, vomiting , polyurea.
11.Geing.
Clinical Significance
Alteration in the patient’s behaviour
Rampant caries
Difficulty with the dentures.
Pathologic conditions which
Increases salivation Decreases salivation
1. Digestive tract irritants 1. Similar atrophy of salivary glands
2. Peptic ulcers 2. Diabetes Millitus.
3. Pain full affection of oral cavity
which may be due to vitamin
deficiency trauma from surgery. All
fitting dentures sharp edged
3. Diarrhoea

restorations carious teeth mucosal
ulcerations
4.Vitamin deficiency
5. Elevated temperature due to acute
infections.
Management of Xerostomia
Management of xerostomia depends on the cause of its condition. If a
drug is suspected to be the cause, consulting with patient’s physicians may
result in the alternate drug therapy. Saliva substitutes are available but
unfortunately have not proven to be acceptable to many patients and are
more expensive also.
Milk has been proposed as a salivary substitute milk not only aids in
lubrication and increases pressure in eating but also has a buffering
capacity. Due to the presence of protein, calcium and phosphorus, milk
prevents enamel demineralization and promotes reminiralization.
Sialogoues (agents which stimulate salivary flow)
- Such as sugar free gums, lozenzes or sugar free candies containing
citric acid may be recommended.
- Sorbitol / xyletol secreting agents / products well decreases the risk of
candiasis.
- An ethanol free rinse containing aloe or landing or water soluble
lubricating jelly can be used.
- Additional recommendations include beverages that may produce
more saliva such as water with slice of lemon / lemonades.

THE ROLE OF SALIVA IN PROSTHODONTICS
Salvia plays an important role in the normal functioning of the
complete denture prosthesis. A moderate amount of saliva is needed to act
as a lubricant buffer between the prosthesis and the mucosa, (to help protect
this sensitive tissue against scuffing as the prosthesis slides over and against
it in function. In addition a thin film of saliva is indispensable in creating
adhesion between the denture base and the mucosa).
Regarding the role played by the intermediate fluid between the base
plate and the mucosa, saliva has generally been compared with that of
water, and it has been taken for granted, especially in experimental
investigations, that the power of fixation attained by the adhesion, cohesion
and surface tension of water is equivalent to that of the saliva.
In order to simply the decision about the influence that saliva might
have on the adhesion between and upper denture and the mucosa, we may
consider the adhesion mechanism between two glass plates with a thin layer
of fluid between them. Let us take H2O as the fluid.
If plates are held horizontally, the intermediate layer of fluid in the
periphery of the plate will be limited by a free layer of fluid. Layer of fluid,
the so called “meniscus”. The form of this meniscus depends on the pressure
within the fluid at the time of examination.
Plates are closer to one another (greater pressure in the
fluid>atmospheric pressure) – meniscus will bulge out, attempts to separate
the plates will cause an inward bulge of the fluid meniscus (decrease
pressure)
Measurement of the force necessary to separate two glass plates with
an intermediate layer of water and from mixed saliva, respectively, will
show that separation requires a greater force if the intermediate layer
consists of saliva.

The meniscus created by the surface tension will act as a spring all
around the edges of the plates, and the tension of that spring will be directly
correlated to the coefficient of the surface tension. This is a very important
factor that holds the plates together.
When a separating force exceeds the elasticity modulus of the fluid
meniscus, the meniscus breaks and an intense flow in the intermediate layer
of fluid will occur. This divides the layer of fluid into two parts, each of
which adheres to the glass plates.
The flow of the fluid is however, diminished by an increased
viscosity. This explains why fresh saliva, despite its lower surface tension,
gives stronger adhesion between the glass plates i.e. the rate of flow is
lowered by the high viscosity of the saliva among to its mucoid content. The
higher the viscosity, the lower the rate of flow and the greater the fixation
power.
b) The amount and viscosity of the saliva is important as it serves two very
important functions a moderate amount of saliva is needed to act as a
lubricant and also to help protect this sensitive tissue against scuffing as the
prosthesi slides over and against it in function.
In addition a thin film if saliva is indispensable in creating adhesion
between the denture base and the mucosa.
Too much Too little

An overly profuse supply of saliva
will not increase the retention and
may complicate the impression
procedure to a degree.
Xerostomea or a ptyalism may be a
systemic disorder such as diabetes
or nephritis.
Excessive sol can be controlled by
having the patient rinse with water
just before the impression tray is
inserted into the mouth, in order to
close the orifices of the salivary
glands partially
It may also be induced by regular
use of certain of the tranquilizing
drugs and may be associated with
nutritional deficiency.
In some cases antisialogogus such
as pamine may be increased.
Thick viscous type of saliva Thick Mucinous type of saliva
This type of saliva sometimes More than 350 palatine glands are

reduces retention by interfering
with intimate contact between the
denture and the mucosa. It may
also interfere with obtaining an
accurate impression of fine tissue
detail, by filling in and bridging
over fine grooves and depressions
so that they are not registered with
complete fidelity in the impression
material. This type of saliva can
usually be controlled for
impression registration with an oral
rinse administered just before
making the impression.
This type of saliva is usually
associated with the patient who has
a marked tendency to gag. `
located in the post 2/3rd
of the
palate. In some mouths these
glands secrete a profuse supply of a
thick mucinous type of saliva that
can interfere with the registration
of an accurate impression (a
mucosa which feels exceptionally
slippery indicates that it is coated
with a layer of thick mucosa)
The mucinous type of saliva can
usually be controlled by means of
mouth wash. Consisting of ½
teaspoon of bicarbonate of soda in
a half of a glass of water this pre
impression rinse has a thinning
effect on the saliva that it is much
less likely to obliterate tissue detail
by intervening at the impression –
tissue interface. If a mouth wash is
not at hand the tandem impression
technique is employed. Where 1st
impression is taken to soak up the
bubbles and mucinous saliva,
followed by a 2nd
impression which
will record the tissue in a relatively
saliva free state.

ARTIFICIAL SALIVA
From the preceding section it is clear than an adequate amount of
salivary flow is essential in the host’s resistance to dental carries and also of
vital importance in the comfortable and successful mastication and
swallowing of food. It plays a vital role in the comfort of denture wearers.
Where salivary flow reduced, salivary stimulants or artificial salivary
substituted have been proposed. Salivary stimulants are most satisfactory in
the form of a pastille which requires chewing, as chewing also acts as a
stimulant. The active ingredient is usually acidic in nature as this is well
known to provoke salivation. Unfortunately this acidity can cause erosion of
the teeth and there is a need for non-acidic forms to be developed. In the
meantime, patients may be advised to chew and suck pastilles or chewing
gum produced for diabetic. These contain sorbitol rather than sugar, they
also have an acceptable PH.
No Artificial saliva that is fully satisfactory has yet been formulated.
Both carboxymethyl cellulose and hydorxyethyl cellulose in aqueous
solutions are in common use and are used as mouthwash as frequently as
required. Neither of these materials has the visco-elastic properties of
natural saliva and both require frequent use to maintain a moist oral
environment. A possible alternative is high molecular might polyethylene
oxide. Although 2% aqueous solution of polyethylene oxide has similar
viscoelastic properties to natural saliva, this sticky, stringing and viscous
liquid is difficult to handle and transport to the mouth. Wafers of pure
polyethylene oxide placed in the buccal sulcus and activated with warm
water have proved more successful, but not all patients cope well with this
procedure and further developments are awaited with interest.
Many artificial saliva solutions for example those used after
radiotherapy to the jaws (which damages the salivary glands and reduce

saliva flow), contain acid. These should be avoided in dental patients if
possible.
Typical formulae for acid – containing and acid – free artificial saliva
solutions saliva are
Acidic solution (Ph approximately 2)
Citric acid 25g
Chloroform spirit 60 ml
Concentrated anise water 10 ml
Methyl cellulose 20 g
Water upto 1 liter
Non acidic solution (Ph approximately 6)
Calcium chloride 0.5g
Magnesium chloride 0.25 g
Potassium chloride 1.25 g
Sodium chloride 1.75g
Dipotassium hydrogen arthophosphate 2.0g
Potassium dihydrogen orthophosphate 0.65g
Sodium fluoride 0.01g
Lemon spirit 16 ml
Sorbitol 85 ml
Methyl cellulose 100g.
Methyl hyroxy – benxoate 4g
Water to 2 liters
While the above solutions can be made by a pharmacist, a promising
commercial mouth lubricant with a PH of approximately 5.4 is
“glandosane” it contains carboxymethyl cellulose together with calcium and
phosphate ions. Saliva orthane has a PH of 7 and is now available
containing sodium fluorides. Instead of methyl cellulose it contains mucin

extracted from the gastric mucosa of pig to provide the appropriate
viscosity.
Artificial saliva can be classified.
1) Depending upon the treatment approach
a) Extrinsic – topically applied artificial saliva
b) Intrinsic – chemically / drug which stimulates salivary gland.
Extrinsic – divided into groups depending upon the presence or absence of
natural mucin.
i) Synthetic
ii) Animal
2) According to research development
1. Ist generation
2. IInd generation
3. Disease oriented
4. Function oriented
5. Custom designed.
Disadvantages
- Poor taste
- Lack of wettability
- Cannot be selectively targeted to different part of oral site.
- Expensive.

CONCLUSION
The secretion of saliva not only varies in rate between different
individuals but also in its composition. Rather than providing just
lubrication for the oral tissues, it is important for the metabolic health of the
mouth as a whole.
Salivary flow rate is nearly zero in sleep. Maximum cariogenic
activity is likely to occur when people eat carbohydrate at night and then do
not brush their teeth before going to sleep.

LIST OF REFERENCES
C.C.Chatterjee 11th
edi. Human physiology
Christopher L.B. Lavelles Applied of the mouth
C.L.B. Lavelle 2nd
edition Applied oral physiology.
D.B. Ferquson Physiology for dental study
William F.Gwaong 13th
edition Review of medical physiology

CONTENTS
• INTRODUCTION
• DEFINITION
• COMPOSITION
• DEVELOPMENT OF THE SALIVARY GLANDS
• SALIVARY CONTROL
• FUNCTIONS
- DIGESTIVE
- ANTIBACTERIAL
- BUFFERING
- LUBRICATION
- SALIVA AND WATER BALANCE
- SALIVA AND TASTE
- EXCRETION
• INACTIVITY OF SALIVARY GLANDS
• EFFECT OF DESALIVATION ON OTHER ORGANS
• SATURATION
• TOOTH INTEGRITY
• HALITOSIS
• PROPERTIES OF SALIVA
• SALIVARY FLUORIDES
• SALIVARY FLOW
• XEROSTOMIA
• ROLE OF SALIVA IN PROSTHODONTICS
• CONCLUSION

COLLEGE OF DENTAL SCIENCES
DEPARTMENT OF PROSTHODONTICS
INCLUDING
CROWN & BRIDGE AND IMPLANTOLOGY
SEMINAR
ON
SALIVASALIVA
PRESENTED BY
DR. MELISSA FERNANDES

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