SALIVA IMPLICATIONS IN PROSTHODONTICS

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SALIVA IMPLICATIONS IN PROSTHODONTICS
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• 1.Introduction
• 2.Source composition Properties.
• 3.Functions.
• 4.Anatomy Histology of Salivary Glands.
• 5.Control of salivation.
• 6.Salivary flow rate.
• 7.Salivary flow and ageing.
• 8.Mastication, Oesophageal Function Saliva
• 9.Xerostomia and its management.
• 10.Sialorrhea.
• 11.Prosthodontic considerations.
• 12.Saliva as a diagnostic tool.
• 13.Conclusion.
• 14.Bibliography.

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INTRODUCTION

• Saliva is largely an unheralded ,unsung and
  ignored secretion.
• Is saliva important? Theres an old axiom
  which states you never miss the water till the
  well runs dry. How true this is, especially for
  saliva. The fact is, a world without saliva is a
  world without pleasure.like living with a
  drought..
• Saliva is most valuable oral fluid that is
  often taken for granted. It is critical for the
  preservation and maintenance of oral health, yet
  it receives little attention until quality or
  quantity is diminished. Consequently it is
  necessary for clinicians to have a good knowledge
  base concerning the norm of salivary flow and
  function

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SOURCE

• Saliva is a clear and slightly alkaline
  mucoserous exocrine secretion. It is a complex
  mixture of fluids, with contributions from major
  salivary glands ,parotid submandibular and
  sublingual, the minor or accessory glands and the
  gingival crevicular fluid. Additionally, it
  contains a high population of bacteria normally
  resident in the mouth , desquamated epithelial
  cells , and transient residues of food or drink
  following their Ingestion.

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• When referring to the fluid normally present
  in the mouth the term whole saliva is commonly
  used, as distinct from duct saliva which is
  that flowing from the individual glands.
• Secretions enter into the oral cavity by way
  of
• Parotid stensens duct- orifice in the cheek
  above the molar teeth.

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• Submandibular gland-whartons duct-sublingual
  caruncle situated to the lingual side of the
  mandible in the submandibular fossa.
• Sublingual gland- Bartholins duct- empties
  along the sublingual fold in the floor of the
  mouth.
• Accessory salivary glands empty through
  individual ducts at their respective locations.

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COMPOSITION

• 99.5water and balance made of solid substances-
  inorganic 0.2,organic 0.3.
• The concentration of which are characterized by
  wide variation , both between individuals and
  with a single individual.
• Organic constituents
• Protein
• 200mg/100ml(only 3 of the protein concentration
  in plasma)
• Enzymes ,immunoglobulins, mucous glycoprotiens ,
  traces of albumin , poly peptides etc.

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• Alpha amylase
• Major digestive enzyme.
• Parotid-60to120mg/100ml.
• Submandibular-25mg/100ml.
• Hydrolysis of alpha 14 glycoside bond- end
  product is maltose.
• Immunoglobulins
• Secretary IgA- predominant-20 mg /100ml
• IgG-1.5mg/100ML
• IgM-0.2mg/100ml,arising from gingival crevice.

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Antibacterial Proteins

• Lysozyme-attacks components of the cell wall of
  certain bacteria leading to lysis.
• Lactoferrin-iron binding protein- removes free
  iron from saliva depleting the supply of iron
  needed for bacterial growth.
• Sialoperoxidase- oxidizes salivary thiocyanate
  ion to hypothiocyanate- potent antibacterial
  substance using hydrogen peroxide produced by
  oral bacteria as an oxidant.

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Glycoprotiens

• MG1 and MG2- submandibular and sublingual saliva
  a group of Proline rich glycoprotiens
  (PRPs)-parotid saliva
• Other poly peptides
• Statherin- rich in tyrosine and proline- inhibits
  the hydroxyapatite crystal growth- inhibitor of
  calculus formation both in glands and on the
  teeth.
• Sialin- helps to regulate the Ph of plaque.

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Other Organic Compounds

• Many free amino acids are present at low
  concentration.
• While saliva can be used by some oral
  bacteria as a sole source of nutrient ,the amino
  acid content is too low to provide a rich growth
  medium.
• Urea - hydrolyzed by many bacteria with release
  of ammonia increase in pH.
• Glucose- 0.5mg/100ml- are too low to support
  extensive growth, but may be raised in diabetics.
  

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Inorganic constituents of whole saliva(mg/100ml)
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• Major ions main contributors to the osmolarity
  of saliva.
• Bicarbonate principal buffer in saliva.
• Fluoride- anticaries action.
• Calcium and phosphate in saliva
• Saliva is super saturated w.r.t hydroxyapatite
  at normal intraoral Ph, submandibular saliva to a
  greater extent than parotid saliva.
• CA10(PO4)6(OH)2 10 CA2 6PO43- 20H-
• ph Decreases- Dissolution
• pH Increases- Rimenarilisation

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PROPERTIES pH

• 6.7 TO 7.4 - whole saliva
• 6.0-7.8 - parotid saliva varies over a greater
  range
• Depends on the bicarbonate concentration-
  concentration of which increase with increase in
  salivary flow.
• Initially saliva is isotonic as is formed in
  the acini but it becomes hypotonic as it travels
  through the duct network .Hypo tonicity of
  unstimulated saliva allows the taste buds to
  perceive different taste and during low flow
  periods allows for expansion and hydration of
  mucin glycoprotiens which protectively blanket
  the tissues of the mouth.

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• Lower levels of glucose ,bicarbonate and urea
  in unstimulated saliva augment the hypotonic
  environment to enhance taste.
• Viscosity
• Viscosity of saliva is non newtonian. It
  exhibits different viscosities at different
  rates of shear , and has visco elastic
  properties.
• Viscous behaviour changes with time after
  secretion because of its non newtonian
  properties and post-secretory degradation of
  mucous glycoprotiens by bacterial enzymes.

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Volume

• Mean daily salivary output -500ml-1500ml.
• Average volume of saliva present in the oral
  cavity is approximately 1 ml. Contribution to
  the Total unstimulated volume of saliva-
• Parotid-20
• Submandibular -60
• Sublingual-5

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Factors influencing the composition of saliva

• Flow rate
• Increased flow rate-increase concentration of
  proteins, sodium chloride and bicarbonate,
  decreased phosphate magnesium.
• Differential gland contributions
• In unstimulated whole saliva parotid glands
  contribute only 20 of fluid volume whereas in
  stimulated saliva they become predominant. Thus
  the composition of the mixed fluid reaches that
  of parotid saliva at high flow rates.

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• Duration of stimulus
• At a constant rate of flow the composition may
  vary with the duration of stimulation.
• Nature of stimulus
• Not biologically significant though salt
  stimulates- increase in protein content ,
  sugar- increase amylase content.

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FUNCTIONS

• Digestion
• Salivary amylase initiates digestion of starch-
  inactivated in stomach- low ph and proteolytic
  activity.
• Starch digestion in the mouth may be either
  beneficial in aiding starch clearance, or
  detrimental in liberating maltose for
  fermentation by oral bacteria to form acid-
  overall effect on caries is still undecided.
• Lubrication
• Aids in speech, mastication, swallowing and for
  general oral health and comfort- property water
  mucous gylcoproteins.

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• Glycoprotiens- high minor sublingual
  secretions,
• Intermediate submandibular low in parotid
  saliva.
• Dilution and clearance
• Effect of water content of saliva is the dilution
  of substances into the mouth and their subsequent
  removal by swallowing or spitting.
• Clearance is more rapid in some parts of the
  mouth than others. Unstimulated saliva is
  present as a thin film covering the hard and
  soft tissues of the mouth the velocity with
  which this film moves over the surface determines
  the rate of clearance of a substance from
  different sites,rapid clearance eg lower
  anteriors and upper posterior teeth.

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• Neutralisation and Buffering
• Saliva is alkaline and is an effective
  buffer system.
• Reduces the drop in plaque ph- cariogenic
  potential of foods.
• Saturation
• Saliva is supersaturated w.r.t tooth mineral-
  responsible for growth of hydroxyapatite crystals
  during the remineralisation phase of the caries
  process.
• Inhibitors of precipitation- statherin
  proline prevents the excessive calcification in
  the mouth, however they cannot penetrate the
  plaque due to large molecular size - unable to
  prevent seeding and calculus formation.

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• Bacterial competition
• Saliva plays a role in the control of the
  bacterial flora by acting as a selective growth
  medium.
• Antibacterial effects
• Pellicle and plaque formation

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CONTROL OF SALIVATION

• The salivary glands are unusual among the glands
  of the digestive tract in being under purely
  nervous control. Hormonal influences can alter
  the composition of saliva but are not responsible
  for its secretion.
• Salivary glands are strongly stimulated by the
  parasympathetic nervous system, the sympathetic
  system has little or no direct effect on
  salivation. The indirect effect , a reduction in
  the rate of secretion from sympathetic
  stimulation is a result of vasoconstriction of
  blood vessels to the gland.

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• Stimulation of submaxillary sublingual glands
  is by superior salivary nuclei. Parotid
  inferior salivary nuclei.
• parasympathetic fibres from-
• 7th nerve - submandibular 9th
  nerve-parotid- are secretomotor and vasodilator.

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ANATOMY AND HISTOLOGY OF THE SALIVARY GLANDS
CLASSIFICATION OF SALIVARY GLANDS

• According to the size
• Major-3pairs
• Parotid
• Submandibular
• Sublingual
• Minor-400 TO 500 .- Glossopalatine, Buccal ,
  Mucous glands of the cheek etc , spread in the
  oral cavity except at the gingiva and anterior
  part of the hard palate.

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• According to the location
• Glands whose duct open in the vestibule
• Lip superior labial and inferior
  labial
• Cheek parotid and buccal.
• Glands whose duct open in the oral cavity proper
• Floor of the mouth submandibular,
  sublingual,
• glossopalatine.
• Tongue Body anterior lingual (of blandin
  nuhn)
• Base posterior lingual, von
  ebner.
• Palate- palatine.

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• According to the type of salivary secretion and
  duct opening
• a serous secretion (thin watery) containing the
  enzyme ptyalin for the digestion of starchy
  foods.
• a mucous secretion (viscid sticky or adhering)
  for lubrication.

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• serous- parotid , von ebner.
• mucous- palatine, posterior lingual
• mixed- predominantly serous - submandibular
• mixed- predominantly mucous-sublingual
• 
  blandin nuhn,
• 
  buccal labial

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• Location of salivary glands

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• Parotid
• superficial portion- in front of the
  external ear deeper part fills the
  retromandibular fossa.
• Submandibular
• In the submandibular triangle behind and
  below the free border of the mylohyoid muscle
  with a small extension lying above mylohyoid.
• Sublingual
• Between the floor of the mouth and the
  mylohyoid muscle- one main gland and several
  smaller glands.
• Labial and buccal glands
• Lips and cheek, although buccal glands are
  not examined by electron microscopy they are
  usually described as continuation of the labial
  glands.

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• Glossopalatine-
• principally localized in the region of isthmus
  in glossopalatine fold.
• Palatine glands-
• aggregates in the lamina propria of the
  posterolateral region of the hard palate and in
  the submucosa of the soft palate and the uvula.
• Lingual
• anteriorlingual -apex of the tongue
• Posterior Lingual (mucous)
• lateral and posterior to the vallate papilla
• Posterior lingual( serous)
• between the muscle fibers of the tongue below
  the valate papilla.

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• Main features of parenchymal cells of salivary
  glands

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• Functions of ducts
• The main function of salivary gland ducts is to,
  convey the primary saliva secreted by the
  terminal secretory units to the oral cavity. They
  are not just passive conduits also they actively
  modify the primary saliva by secretion and
  reabsorption.
• Essentially all of the water enters saliva at the
  level of terminal secretory units, the striated
  and excretory ducts appear to be relatively
  impermeable to water

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SALIVARY FLOW RATE

• Flow rate volume (milli litres) of saliva
• minute
• there is great variability in individual
  salivary flow rate. The accepted range of normal
  flow ml/min is as follows

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• Methods of measurement of flow rate
• techniques for assessing salivation salivary
  secretion rate has been reviewed and evaluated by
  many authors.
• Accurate measures of salivary flow rate are
  required for a variety of clinical and
  experimental situations.

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• Two methods- a.measurement of whole saliva
• b.measurement of
  parotid saliva..
• Techniques for measurement of whole saliva
  unstimulated (resting)
• Draining method
• Spitting method
• Suction method
• Swab method

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Techniques for collection stimulated whole saliva

• Masticatory method (standardized piece of
  paraffin used)
• Gustatory method(1 to 6 citric acid used )
• The spitting method for estimating resting flow
  and masticatory method with paraffin chewing for
  stimulating saliva for measuring flow rates are
  reliable.

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SALIVARY FLOW AND AGEING

• Flow rate of unstimulated (resting )whole saliva
  with age
• Since 70 of whole resting saliva comes from
  submandibular and sublingual glands , the
  decrease in its flow with age must largely be
  due to decrease in production.
• Histological findings demonstrate that there is
  20 to 30 decrease in volume of salivary acini
  with age.
• On the other hand numerous functional studies
  have failed to show any age related decrease in
  the flow of parotid saliva as the normal resting
  flow rates of parotid saliva are extremely small
  0.04 to 0.06 ml/min .Therefore often no saliva
  can be obtained and the frequency of not
  obtaining it increases with age .

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• Flow rate of stimulated whole saliva
• The relationship SFR and ageing- of whole
  saliva is mixed. Most studies show no change or
  only a modest decrease in flow rate even though
  the histological findings show a significant
  decline in the volume of salivary acini. The fact
  that this acinar reduction does not affect the
  stimulated flow rate of saliva should not be
  surprising- most organs when stimulated,
  compensate for the loss of parenchyma.
• Other factors influencing salivary flow rate
• Diurnal variation, drugs, source of saliva, diet,
  duration and type of stimuli, hormones

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MASTICATION ,OESOPHAGEAL FUNCTION AND SALIVA
Decreased mastication and saliva

• Mastication is the exercise of the oral
  apparatus. Chewing increases ,function and lack
  of chewing induces atrophy of disuse. Indeed
  impaired mastication is associated with a
  reduction in the mass of salivary gland and a
  decrease in the synthesis secretion of saliva.
• Findings indicate that the partial or total
  loss of teeth, the presence of dentures , the
  decrease in bite force, TMJ dysfunction ,
  extensive caries , pdl disease , pain ,
  immobilization of jaws and other clinical
  conditions contribute to in flow of saliva and
  salivary gland hypofunction.
• Implicit in these findings is that dentists
  should place a high priority in restoration of
  masticatory function.

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• Increased mastication and saliva
• Chewing induces an increase in the flow of
  stimulated whole saliva.
• This facilitates taste, swallowing and
  alimentation, enhances clearance, buffers harmful
  oral and oesophageal acids and aids in the
  remineralisation of teeth .
• Given the beneficial effects of stimulated saliva
  it is not surprising that considerable attention
  is given to agents which stimulate saliva eg
  chewing of paraffin wax ,sugarless chewing gum
  can increase flow, diminish the fall in plaque pH
  accumulation of harmful acids. Clinical trials
  have therefore shown that chewing sugarless gums
  reduces incidence of dental caries .

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• Saliva and oesophageal function
• The reflux of gastric acid and food into the
  lower oesophagus-gastro oesophageal reflux (GERD)
  is a common condition that is associated with
  heart burn and nausea.
• The clearance of acids from the oesophagus, like
  that of the mouth is a two stage process and
  saliva plays a significant role in it. Influx of
  saliva Vmax induces swallowing- initiates first
  phase of oesophageal clearance (primary
  peristalsis) This is manifested as a peristaltic
  wave which clears 90-95 of refluxed acid. A
  small amount of acid 5 remains, which is diluted
  and buffered by successive swallows of stimulated
  saliva .
• Therefore patients with xerostomia, sjogrens
  syndrome and rheumatoid arthritis- advised to
  take chewing gum and sugarless candies and
  cholinergic agonist like pilocarpine.

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• Clearance , residual saliva and oral dryness
• The mouth is a receptacle into which , for
  about 14 hrs of the day ,there is an influx,
  distribution and efflux of about 350 ml of
  resting saliva, additionally about 2hrs of the
  day variety of solids and liquids and about 250ml
  of stimulated saliva , enter or placed in the
  oral cavity. The process whereby substances are
  removed is known as salivary clearance. Central
  to this process are the act of swallowing and the
  flow of saliva.

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• Following deglutition there is progressive influx
  of unstimulated saliva. This is distributed
  throughout the mouth, where it mixes with and
  dilutes it contents, and coats the oral mucous
  membrane. As the volume of saliva increase it
  soon reaches a maximum volume, at which point
  another swallow occurs and the process starts
  all over again.
• A small amount of saliva , as well as the
  substances contained within it remain in the
  mouth. This is referred to as residual saliva-it
  sticks as a thin film to the mucous membrane and
  surfaces of the teeth and flows into the
  interstices between teeth.

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• Some of the substances dissolved in this residual
  saliva, enzymes antibacterial peptides,
  antibodies, are protective to the oral cavity.
  Others like sugar and carbohydrates are
  potentially harmful.
• The clearance process is described as similar to
  tidal exchange where following the ebb tide,
  there remains tidal pools and the ecosystem
  contained within them. Whichever analogy is used
  ,it should be clear that, with exception of
  substances wanted to be retained in the
  mouth-fluoride and chlorhexidine, fast clearance
  favors health and slow rates favors disease.

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• The volume of residual saliva was largely
  dependent on the max volume V max before
  swallowing- mean value 1.07ml and the resting
  flow rate of whole saliva.The mean volume of
  residual saliva -0.77ml.
• Average thickness of the residual saliva film on
  oral tissues Vmax
• total surface area of
  the oral tissues.
• 0.036to 0.05mm.
• Because of the variation in the distribution of
  saliva the shape of the teeth and their
  disposition in the maxilla or the mandible the
  thickness of the film varies.

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• Palate and the upper lip were the driest and
  covered with least amount of saliva floor of the
  mouth and dorsum of the tongue were wettest.
• Dryness is alleged ,is dependent on the volume of
  saliva present on the oral mucous membrane and
  the rate of its evaporation from them. Hard
  palate fewer glands, far away from the orifices
  of major glands and is the area of high
  evaporation.
• it is proposed that the thickness of the film of
  residual saliva on the hard palate is a valid
  indicator of the degree of oral wetness and
  xerostomia.

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XEROSTOMIA

• It is a subjective sensation of a dry mouth,
  frequently but not always associated with
  salivary gland hypofunction.
• Dryness of mouth is one of the oldest symptoms
  recorded by man.
• Ancient records describe the use of rice tests to
  determine guilt or innocence if
  innocent-ingestion of rice will stimulate the
  flow of saliva, if guilty mouth will be dry and
  swallowing difficult or even impossible.

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• PREVALANCE

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• HOW DOES THE SENSATION OF ORAL DRYNESS CORRELATE
  WITH THE FLOW OF SALIVA?
• Fox et al. Concluded that oral dryness was not
  a valid indicator of salivary hypofunction.
• Sreebny validini also showed that dry mouth per
  se was not a valid indicator of salivary
  hypofunction.Their findings slightly more than
  half (54)of the subjects who complained of
  xerostomia had resting whole saliva flow rates
  abnormally low (0.1ml/min)
• Xerostomia is rarely a solitary symptom.
  Accompanying it is a wide variety of other oral
  and non oral complaints.

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CAUSES OF XEROSTOMIA
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• Overall the most common cause of decreased
  salivary output is the intake of drugs.
• A wide variety of medications referred to as
  Xerogenic drugs induce oral dryness.
• Prevalence of xerostomia is not only related to
  drugs that are xerogenic but to the total number
  of drugs taken. As a general rule the drying and
  hyposalivatory effects of drugs are transient.
• Anticholinergic, antidepressants ,
  antihistamines, antipsycotic, antihypertensives,
  sedatives, diuretics and analgesics.

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• Diagnosis of xerostomia
• Clinically
• Medical history, H/o radiation chemotherapy, oral
  infections, questionnaire.
• Dentists should provide the patients with a dry
  mouth questionnaire-
• Do you sip liquids to aid the swallowing of
  foods?
• Does your mouth feel dry when eating?
• Do you have difficulties swallowing any foods?
• Does your mouth usually become dry when you
  speak?
• Lab tests flow rate tests , sialometry ,etc.

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• MANAGEMENT
• Reassurance, symptomatic and supportive care.
• Patient education- to compensate for the oral
  dryness patient may stop chewing prefer a
  liquid or a semisolid diet rich in fermentable
  carbohydrates.
• Because decreased mastication worsens the
  condition , patients should undergo nutritional
  counseling to limit the harmful effects of
  reactionary diet modifications.

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• Patient should be reminded to chew , as
  periodontal mechanoreceptors mechanical
  stimulation of the tongue oral mucosa are vital
  stimuli for salivation. Sugar free candies
  chewing gum are recommended .
• Use of medication before bed time should be
  discouraged as this time of the day coincides
  with lowest salivary flow rate.
• Should sip cool water throughout the day and
  drink milk with their meals.

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• Water is a poor mucosal wetting agent, lacks
  buffering capacity, lubricating mucins. Whole
  milk may serve as a better substitute. Citrus
  fruits, caffeine and alcohol, alcohol containing
  mouth washes cause dehydration must be avoided.
• sleep on the side to reduce mouth breathing,
• Apply petrolatum based lubricants to lips during
  the day bedtime
• Cool air humidifier be placed in the room.
• Medication -capable of stimulating salivary
  glands- pilocarpine -5 to 10 mg ,3 or 4 times
  daily, 30 min before meals administered.

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• ARTIFICIAL SALIVA SUBSTITUTES
• Commercially available products contain
• Carboxy methylcellulose lubrication,
• Animal mucins to increase viscosity,
• Parabens- inhibit bacterial growth,
• Sugar free agents- xylitol, sorbitol- sweetners,
  mineral salts- simulate electrolyte content,
• Flouride- reminaralisation.
• Trade names salivart(spray), mouthkote (spray),
  oral balance (gel).
  
• The oral mucous and the intaglio surface of
  prosthesis can be sprayed throughout the day with
  artificial saliva .

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• Electrical stimulation- SALITRON-.battery
  operated devices which deliver an electrical
  stimulus to the tongue and palate for saliva
  production.
• Acupuncture.
• Future aspects
• gene therapy
• tissue engineering.

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• Therapeutic irradiation of the head and neck
• Xerostomia and salivary gland hypofunction are
  almost inevitably seen in patients whose salivary
  glands are irradiated for head and neck cancer.
• Sensation of oral dryness occurs early in the
  course of radiation. It has been shown that 24
  hrs after administration of only 2.25 Gy(225Rads)
  there is already a 50 decrease in flow of the
  parotid saliva.
• When exposure exceeds 50Gy (5000Rads) the
  reduction in flow is profound for the most part
  permanent , the decrease amounts to gt90.
• Parotid glands are the most sensitive to ionising
  radiation the other glands in the decreasing
  order of sensitivity- submandibular, sublingual
  and the minor glands.

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• In Preventive therapy maintain impeccable oral
  hygiene,
• schedule frequent recalls , use topical flouride
  regime.
• Prosthodontic management
• Thorough case history
• Elastomeric impression materials preferred.
• In the partially and fully edentulous patient,
  susceptibility to mucosal ulcerations fungal
  infections- patient should be made aware of the
  well fitting denture minimize denture use at
  times when salivary flow is noted.
• Patient should be made aware of a well fitting
  denture and minimize denture use at times when
  decreaesed salivary flow is noted.

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• Artificial saliva reservoir
• Fabrication of intra oral reservoirs
• Construct the maxillary denture with an accepted
  technique. provide the maximum inter arch space
  possible with an acceptable vertical dimension of
  occlusion.
• thicken the external palatal surface of the
  trial denture with wax.
• soften the wax and contour its surface with
  functional movements of the tongue (swallowing,
  speech , mastication).
• Complete the wax up, ,invest it , and boil out
  the wax.

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• Construct a chrome cobalt palatal plate on a
  duplicate cast cover the palate to the palatal
  portion of the alveolar process beginning of
  the post palatal seal. Post palatal seal not
  included in the metal to decrease the weight of
  the denture to prevent premature loss of the
  artificial saliva due to leakage between metal
  and acrylic resin parts of the denture. The metal
  palate is 0.45mm thick at the center 1mm thick
  where it joins the acrylic base.
• Drill two filling holes 1.5mm in the metal base
  one anterior and one posterior to the midline.
• Glue the metal base to the flasked cast.
• Fill the maximum space available for the
  reservoir with optosil which is then glued to the
  metal base .

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• space for acrylic resin must remain between the
  filler and the investment
• Pack and cure the acrylic resins into the flask
  in the usual manner.
• Remove the metal base and the filler from the
  denture and reattach the metal base into the
  denture. The border of the metal base interlocks
  with the acrylic resins internal surface of the
  palate .
• Drill a saliva release hole (0.1 to 0.2) in the
  reservoir at the midline of the denture 5mm
  palatal to the anterior teeth.

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SIALORRHEA

• Excessive salivation often experienced by the
  individual
• and experienced by the individual noticed
  by the operator.
• Prosthodontic management
• Impression making mouth irrigated with an
  astringent.
• Mouth washed prior to investing impression
  material.
• Fast setting impression material is used.
• Anti sialagogues administered 1to 2 days before
  treatment
• Dummy dentures are fabricated given.

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Prosthodontic Considerations

• From the prosthodontists point of view, salivary
  glands are of great importance both anatomically
  and physiologically.
• Extension of denture base
• Stensens duct- it is rare for a maxillary denture
  to cause obstruction to this duct.
• whartons duct-extension of the lingual flange in
  this region can lead to obstruction patient
  complains of swelling under the tongue while
  eating.
• Sublingual- it is rare for a denture to cause any
  significant obstruction.

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• Amount of saliva
• Will effect the denture construction process
  quality of the final product.
• If a mouth is dry . Retention of the denture
  affected increased potential for soreness.
• Excess saliva- complicates denture construction-
  impression making.
• When new dentures are first inserted increased
  salivation due to temporary increase in salivary
  flow is a natural response to foreign object in
  time will subside. Patients need assurance about
  this.
• Deglutition will be necessary to evacuate the
  excess - advised not to rinse and spit as this
  unsettling of the denture bases.

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• Consistency
• Best to work with a serous type of saliva.
• Presence of thick saliva may create a problem for
  maxillary complete denture retention,-create
  hydrostatic pressure in the area anterior to the
  post palatal seal area- downward dislodging force
  exerted upon the denture base.
• In an effort to alleviate this problem, a cupids
  bow can be scribed on the master cast .
• Watt and macgregor feel that extension of the
  posterior palatal seal line will contain the
  thick mucous in the posterior part of the denture
  to provide a seal even if the posterior portion
  of the denture base is slightly out of contact
  with the palatal tissues.

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• Thick saliva also complicates impression making
  by forming voids in the impression surface while
  the impression sets- palatal surface should be
  wiped free of saliva the mucous glands massaged
  with a piece of gauze just before the final
  impression is made to eliminate as much as mucous
  as possible.
• It may also be factor for the patient to gag
  while impressions are made and after the
  placement of new dentures.

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Role of saliva in denture retention

• Saliva is considered as a major factor in
  evaluating the physical influences that
  contribute to the denture retention .
• The physical forces in which saliva is involved
  are
• Adhesion
• cohesion
• atmospheric pressure
• capillary attraction
• peripheral seal
• Viscosity of saliva Surface tension.

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• Adhesion
• Adhesion is the physical attraction of unlike
  molecules for each other.
• It acts when saliva sticks and wets to the basal
  surface of the dentures at the same time to the
  mucous membrane of the basal seat. A watery
  saliva is quite effective , provided the denture
  base material can be wetted.
• Saliva that is thick ropy adheres well to both
  the denture base and the mucosa but since much
  of it is produced by the palatal glands under the
  maxillary denture base it builds up pushes the
  denture out of position. The forces of adhesion
  still act on them but the hydraulic pressure
  produced by the thick mucus secretion over power
  them.
• The amount of retention provided by adhesion is
  directly proportional to the area covered by the
  denture

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• Cohesion
• Retentive force as it occurs in the layer of
  saliva between the denture base the mucosa.
  Since saliva is a liquid the layer should be thin
  if it is to be effective.
• Interfacial surface tension
• Is the resistance to separation possessed by the
  film of liquid between two well adapted surfaces.
  It again found in the thin film of saliva
  similar in its action to cohesion and to
  capillary attraction.

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• Capillary Attraction
• Is a force that causes the surface of a liquid
  to become elevated or depressed when it is in
  contact with a solid.
• Peripheral Seal
• Developed with the proper extension of the
  denture into the vestibule.
• Denture border merging against the mucosal border
  assembled by a thin film of saliva provides
  border seal as it prevents ingress of air , thus
  enabling the denture to be in their position.

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• VISCOSITY OF SALIVA
• Analogies are usually drawn between the clinical
  situation the two circular parallel plates
  separated by the liquid. Under these conditions
  Stephens law can be applied

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• Relationship expressed in equation 2 shows that
  the force required to displace a denture is
  proportional to the viscosity of saliva fluid
  film the square of area of the denture
  inversely proportional to the square of the
  distance separating denture from the supporting
  tissues the time of force application .
• Degree of retention possessed by the denture
  depends critically on the area of its
• fitting surface hence the requirement to
  extend the denture base to the maximum allowed
  by the muscle insertion.
• degree of closeness of fit.
• Viscosity of the saliva
• The glycoprotiens the proteoglycans
  dissolved in the saliva not only increase the
  viscosity but provide it with

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• pseudo plastic properties. When low shear
  stress is encountered in the mouth when
  mastication is not taking place , saliva acts as
  a semisolid.
• equation 1. and 2. are valid if we assume that
  the circular parallel plates are completely
  immersed in the liquid. In mouth the dentures are
  not immersed all the time , hence a meniscus can
  form at the periphery and surface tension can be
  included as a factor.
• Laplace formula

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• Any positive effect that surface tension has must
  depend on their being an intact saliva/air
  interface at the periphery of the denture, a
  condition which could exist only during speech.
  When eating and drinking the integrity of any
  peripheral saliva/air interface would be
  destroyed and the effect of surface tension
  becomes negligible.Therefore emphasis is placed
  on close fit and accurate impression technique

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SALIVA AS A DIAGNOSTIC TOOL

• Saliva is not widely used as a indicator of
  health . disease. However salivary testing is
  becoming more common as clinicians have begun to
  appreciate its advantages investigators defined
  its worth.
• Salivary levels of drugs detected following
  therapeutic medications.
• Saliva drug testing kits are commercially
  available. Included in these are the tests for
  alcohol, cocaine HLA typing, HIV1 ,HIV2 ,DNA,
  etc
• Salivary cortisol is an indicator of hypothalamic
  pituitary

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• adrenal axis function- used to quantify the
  human stress to determine the effect of
  treatment on it.
• to detect antibodies-hepatitis A, rubella virus,
  etc
• to diagnose systemic disease after salivary gland
  dysfunction- sjogrens syndrome, alzheimers
  disease, cystic fibrosis,etc.
• Forensic odontology
• Salivary pH assessment using telemetry
• Device called telemetry system is
  incorporated in the denture which has a
  radiosensitive diode, oscillator, ph sensor, and
  a computer analyzer.

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CONCLUSION

• The multi factorial role of salivary components
  continue to represent a focused area of dental
  research.
• The knowledge of normal salivary composition,
  flow function is extremely important on a daily
  basis when treating patients.
• Dental health professionals spend untold hours
  removing this precious natural resource to
  perform therapy, with little regard to its value
  until flow is significantly reduced.
• Whether saliva occurs in quantities large or
  small , recognition should be given to the many
  contributions it makes to the preservation
  maintenance of oral systemic health.

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