SALIVA
Saliva is not one of the popular bodily fluids. It lacks the drama of
blood, the sincerity of sweat and the emotion...
 Consistency – slightly cloudy because of the presence of cells and
mucin.
 Reaction – usually slightly acidic (PH 6.02 ...
FUNCTIONS
I Mechanical function
1. It keep the mouth moist & helps speech
2. It helps in the process of mastication of the...
VII Buffering action – Mainly bicarbonate and to a lesser extent phosphate
and mucin present in saliva act as buffers.
VII...
DEVELOPMENT OF THE SALIVARY GLANDS
The 3 major sets of salivary gland – the parotid, the submandibular,
and the sublingual...
SALIVARY CONTROL
AFFERENT PATHWAYS
The rate of salivary gland secretion may be affected by 3 principal
factors.
a) Local f...
nerves, with the spinal reflex centers being influence by the medulla and
higher centers eg. Hypothalamus. This area, the ...
FUNCTIONS OF SALIVA
1) DIGESTIVE FUNCTION
The only important digestive enzyme present in saliva is PTYALIN
(or salivary am...
1) Saliva increases capillary permeability
2) Mixed saliva possesses leucotaclic activity i.e. the power of attracting
pol...
Effect demonstrated by pouring a suspension in agar of one species of
organisms over previously grown colonies of other or...
mouth is dry. These glycoproteins are at high concentrations in the minor
mucous gland and sublingual gland secretions, in...
route of excretion for substances that are either destroyed or rendered
insoluble during their passing through the gut aft...
THE EFFECT OF DESALIVATION OF OTHER ORGANS.
Removal of salivary glands
Salivary flow
Intake of food
Fall in body weight es...
lost mineral through the organic matrix of the enamel to crystal.
Supersaturation of minerals in saliva is critical to thi...
III. HALITOSIS (Factor aris, bad breath)
This is a condition which is almost universal if the, odor of breath on
waking is...
PROPERTIES OF SALIVA
1) Viscosity and spinnbarkeit.
Saliva is a viscous fluid and also show the property of spinnbarkeit
w...
important buffers, that phosphate plays some part but that, contrary to
previous views, the proteins can be disregarded as...
SALIVARY FLUORIDE
The role of saliva in the mode of action is now well recognized.
Fluoride may reach saliva directly from...
cavity. The unstimulated flow rates varies considerably during the day, and
is influenced by a number of factors.
Factors ...
Pavlov, who did that the animals learned to associate the chewing of church
bells with meal times and would salivate on he...
as an attempt to dilute or neutralize the irritant which is giving rise to the
nausea.
Hypersalivation (PTY slims) is also...
XEROSTOMIA (Dry mouth syndrome)
Xerostomia is a subjective feeling of oral dryness. It is generally
accompanied by salivar...
- Skin – Dryness and butterfly rashes
- Joints – Pain, swelling and stiffness of the joints.
- GIT = Constipation.
General...
restorations carious teeth mucosal
ulcerations
4.Vitamin deficiency
5. Elevated temperature due to acute
infections.
Manag...
THE ROLE OF SALIVA IN PROSTHODONTICS
Salvia plays an important role in the normal functioning of the
complete denture pros...
The meniscus created by the surface tension will act as a spring all
around the edges of the plates, and the tension of th...
An overly profuse supply of saliva
will not increase the retention and
may complicate the impression
procedure to a degree...
reduces retention by interfering
with intimate contact between the
denture and the mucosa. It may
also interfere with obta...
ARTIFICIAL SALIVA
From the preceding section it is clear than an adequate amount of
salivary flow is essential in the host...
saliva flow), contain acid. These should be avoided in dental patients if
possible.
Typical formulae for acid – containing...
extracted from the gastric mucosa of pig to provide the appropriate
viscosity.
Artificial saliva can be classified.
1) Dep...
CONCLUSION
The secretion of saliva not only varies in rate between different
individuals but also in its composition. Rath...
LIST OF REFERENCES
C.C.Chatterjee 11th
edi. Human physiology
Christopher L.B. Lavelles Applied of the mouth
C.L.B. Lavelle...
CONTENTS
• INTRODUCTION
• DEFINITION
• COMPOSITION
• DEVELOPMENT OF THE SALIVARY GLANDS
• SALIVARY CONTROL
• FUNCTIONS
- D...
COLLEGE OF DENTAL SCIENCES
DEPARTMENT OF PROSTHODONTICS
INCLUDING
CROWN & BRIDGE AND IMPLANTOLOGY
SEMINAR
ON
SALIVASALIVA
...
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  1. 1. 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.
  2. 2.  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.
  3. 3. 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.
  4. 4. 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.
  5. 5. 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”
  6. 6. 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
  7. 7. 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.
  8. 8. 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.
  9. 9. 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.
  10. 10. 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
  11. 11. 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
  12. 12. 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.
  13. 13. 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
  14. 14. 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.
  15. 15. 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.
  16. 16. 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
  17. 17. 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.
  18. 18. 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
  19. 19. 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
  20. 20. 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
  21. 21. 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)
  22. 22. 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.
  23. 23. - 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
  24. 24. 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.
  25. 25. 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.
  26. 26. 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
  27. 27. 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
  28. 28. 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.
  29. 29. 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
  30. 30. 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
  31. 31. 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.
  32. 32. 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.
  33. 33. 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
  34. 34. 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
  35. 35. COLLEGE OF DENTAL SCIENCES DEPARTMENT OF PROSTHODONTICS INCLUDING CROWN & BRIDGE AND IMPLANTOLOGY SEMINAR ON SALIVASALIVA PRESENTED BY DR. MELISSA FERNANDES

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