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Dentistry Year 2 OCB > Functions of Saliva > Flashcards

Functions of Saliva Flashcards

1
Q

How many ml of saliva is secreted in each case:

  • Unstimulated
  • Sleeping
  • Stimulated
A

Unstimulated = 0.35ml/min

Sleeping = 0.1ml/min

Stimulated = 2.0ml/min

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2
Q

How much saliva is released per 24hours?

A

600ml

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3
Q

What rhythm is saliva released in and explain this?

A

During the unstimulated period, there is a circadian rhythm. If you sample salvia during unstimulated flow at certain times of the day, there are different flow rates. 6-9am, unstimulated salivary secretion is likely to be at its lowest and at its highest around 3pm-6pm. This can vary by around 70%.

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4
Q

Why do we release less saliva when sleeping?

A

Sleeping can be explained in terms of the reflex stimulation.
Impact of CNS higher centres on rate of secretion. Tends to be a positive influence. CNS activity is greatly reduced during sleep.

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5
Q

What salivary glands release more when the mouth is unstimulated and stimulated?

A

Unstimulated = submandibular and sublingual

Stimulated = Parotid

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6
Q

What protein do minor salivary glands contribute a lot to?

In what conditions is this useful?

A

Mucin

Under resting conditions, saliva is likely to have a higher mucin concentration. This helps to coat surface and provide protection.

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7
Q

What values when stimulated and unstimulated are very low?

A

Unstimulated = <0.1ml

Stimulated = <0.7ml

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8
Q

What affects salivary flow rates?

A
  • Decreases in the elderly
  • Are reduced by a wide range of prescribed medications
  • Correlate to the size of salivary glands
  • Tend to be higher in males compared to females
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9
Q

What surfaces have the thickness and thinnest biofilm layer?

A

Thickness is seen on the anterior tongue and thinnest on anterior hard palate.

(variety comes with the proximity to salivary glands)

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10
Q

What are the symptoms of dry mouth?

A
  • Night waking due to dryness
  • Burning sore mouth
  • Candidiasis
  • Bad taste
  • Dental caries
  • Discomfort wearing dentures
  • Difficultly speaking/eating
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11
Q

How many micro-organisms are approx in ml of saliva?

A

10^8

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12
Q

Apart from the salivary composition produced from salivary glands, what else can be found in saliva?

A

Products from enamel/dentine work into saliva.
Gingival crevicular fluid contribution - albumin mainly from here. Cellular contribution as there is a steady movement of neutrophils into saliva.
Mucosal surfaces with constant shedding of oral epithelial cells.

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13
Q

Name all the components of saliva

A 
Cells (epithelial&neutrophils)
Micro-organisms
Microparticles
Mucin glycoproteins 
Proteins 
Antibodies
Cytokines
Electrolytes/ions
Lipids
Steroidal hormones 
DNA
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14
Q

What are the 4 main functions of saliva?

A
  1. Tooth protection
    - Increased oral clearance
    - Buffers pH
    - Acquired enamel pellice
    - Saliva supersaturation with calcium phosphate
  2. Protection and maintenance of the oral mucosa
    - Wound healing
    - Lubrication
    - Moistening
    - Barrier formation
  3. Regulate oral microbiota
    - Clearance, killing and agglutination of pathogens
    - Colonisation, adhesion, feeding of commensals
  4. Taste and processing of food/nutrients
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15
Q

How does flow rate affect caries risk?

A

Very low salivary flow greatly reduces clearance of sugar and bacteria and therefore increases risk of caries

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16
Q

Why is buffering important?

A

Bicarbonate buffers the acid present, either dietary or bacteria acid.

Much more bicarbonate in stimulated saliva. This is helpful in neutralising dietary acid.

Salivary bicarbonate concentration:
Resting = 1mM
Stimulated = 30mM

17
Q

Explain what the acquired enamel pellicle is

A

Early pellicle formed by calcium binding salivary proteins in saliva (including statherin, histatines, and acidic proline-rich proteins.

It prevents surface mineralisation but enhances sub-surface remineralisation.

Lubrication (reduces friction by 20 fold).

The proteins prevent precipitation of calcium from saliva onto the tooth surface. The acquired pellicle stops the precipitation of the salivary calcium and phosphate ions.

18
Q

Explain how saliva causes tooth remineralisation

A

Remineralisation is depends upon supersaturation of saliva with calcium and phosphate.

Concentration of calcium in resting saliva is 2mM.
This is due to statherin protein.

Critical pH of enamel = 5.5
Due to acid binding to hydroxy ions in saliva and shift the equilibrium to the right so the tooth surface is solubilised. Causes demineralisation.

19
Q

How does saliva interact with soft tissues?

A

Film contains a network of protein. The protein is a salivary mucin, a large molecule forming a pore containing network within the salivary film. This network controls the way certain components of saliva have access to the mucosal surface.
Top right graph shows the small components of saliva move as easily through mucin network as it does through an aqueous solution.
Larger components have harder restriction in movement through the mucin network. Shows the oral bacterium being restricted to moving through the mucin layer (5% movement compared to aqueous solution) showing bacteria finding it harder to move through the mucin pores. This produces a barrier to bacteria movement.

As well as this, the mucin helps to increase lubrication of the soft tissue. 2 mucosal surfaces that rub against each other, when coated with mucin salivary film, they move against each other with reduced friction.

20
Q

How does saliva regulate micro-organims?

A
  • Flow of saliva clears MO from mouth
  • The acquired enamel pellicle modifies the adherence of MO to teeth. Salivary proteins in the enamel pellicle provide binding sites for commensal bacteria
  • Salivary agglutination, muffins and other proteins in saliva aggregate MO and facilitate clearance from the mouth
  • Salivary proteins can modulate MO growth
  • Saliva contains many anti-microbial, growth limiting factors

Dentistry Year 2 OCB (30 decks)

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