saliva Flashcards
What are the two (umbrella) functions of saliva?
Protection, Digestion
What are the protective functions of saliva?
- Lubrication
- Hydration
- Maintaining pH/buffering
- Preventing demineralisation
- Host defences
What are some host defences of saliva?
- Immunological (slgA)
- Clearance (saliva flow)
- Antibacterial (lactoferrin, lysozyme, lactoperidoxidase)
- Antiviral (slgA/mucins)
- Antifungal (histatins)
What is slgA?
An antibody with four binding sites which aggregates microorganisms, inhibiting tissue adhesion
What is lactoferrin?
An iron binding protein which works by starving microbes of iron, causing them to die.
What is lysozyme?
An enzyme which weakens the cell wall, causing a cell to lyse or burst.
What is lactoperoxidase?
An enzyme which generates hypothiocyanite ions, meaning acid production in plaque decreases.
What are histatins
Histidine rich proteins which have antimicrobial functions by inhibiting respiration (candida albicans)
What is the function of calcium in saliva?
Calcium prevents demineralisation and drives remineralisation of teeth along with phosphate.
What is the importance of saliva’s lubricating properties?
Means that food can be swallowed without damaging tissues
What is the importance of saliva’s clearance properties?
Unwanted foreign objects or microbes can be cleared and thus disease/tissue damage can be prevented.
What is the significance of the acquired pellicle?
Protects teeth and allows microbes (plaque) to stick.
What is concentrated in the acquired pellicle?
Calcium
What are the digestive functions of saliva?
- Enzymatic
- Bolus formation
- Taste
What enzyme in saliva breaks down starch?
Amylase
What enzyme in saliva breaks down lipids?
Lipase
Why are citrus juices particularly nasty?
Citrate is a chelating agent which bonds to ca2+ ions, removing them from equilibrium and causing erosion due to additional low pH
What is the critical pH for demineralisation
5.5
What happens when oral pH drops below 5.5?
Calcium and phosphate ions are actively being leeched out of the tooth-> demineralisation.
What is the resting pH of the mouth?
6.5-7
How long does it take after a sugar intake for pH to reach min.?
10 minutes
How long does it take for pH to recover to 5.5?
30-60 mins, remineralisation begins.
What does bicarbonate do in saliva?
It is a weak base which buffers the equilibrium and forms a complex with H+ ions from carbs, which means the tooth is no longer affected by acid.
What enzyme catalyses the bicarbonate reaction?
Carbonic anhydrase
Where is carbonic anhydrase concentrated?
In the acquired pellicle.
Why does xerostomia effect the rate of demineralisation?
This recovery process is much slower and thus the tooth is attacked for longer, more demineralisation can occur.
What are some causes of xerostomia?
medical conditions, medication, radiation, eating disorders, diabetes.
What is sjögren’s syndrome?
A chronic autoimmune disorder which results in hyposalivation among other things.
What are some factors influencing caries suceptability?
- Salivary buffering capacity
- Salivary flow rate
- Salivary content of mutans streptococci
What is mutans streptococci?
The caries pathogen
How much saliva is typically produced per day?
0.5-1 litre
Where is saliva produced?
Special exocrine glands
Is saliva hypotonic or hypertonic?
Hypotonic- it hydrates the oral tissues.
