Prevention of caries by saliva Flashcards
Name the 4 static effects of saliva
- Antibacterial
- Supersaturated Ca/P
- Pellicle formation
- Plaque substrates (e.g. urea)
Name the 3 Dynamic effects of saliva
Buffering (bicarbonate increases with flow)
Clearance of sugars/acids
Supersaturation (increases with flow)
Which salivary gland do you find under the tongue?
Sublingual
located under floor of the mouth and below either side of the tongue
Where are the parotid salivary glands located?
Located just in front of the ears
Where are the submandibular glands located?
Located below the jaw
Minor salivary glands contribute what percentage of total salivary flow?
around 10%
Do all the salivary glands produce saliva with the same components?
No - each gland has a specific salivary protein profile; salivary proteins are synthesised specifically by the glands
What type of process is making saliva?
It is an osmotic process - saliva glands secrete lots of sodium and chloride into ducts which helps draw in water via osmosis
Which 2 ions stay at a similar level in both resting and stimulated states?
Phosphate
Calcium
Levels of which ions increase when the parotid salivary gland is stimulated/increase with flow rate? (3)
Sodium
Chloride
Bicarbonate
What cells make saliva?
Acini cells (sing. Acinus)
What 2 cells are involved in salivary glands?
Acini
Striated ducts
What do the striated ducts do in the formation of saliva? (2)
They absorb some sodium and chloride out of the saliva (but this process cannot keep up with stimulation - which is why levels increase)
They take up potassium and bicarbonate into the saliva
Outline how saliva is bacteriostatic (2)
- PRPs (proline-rich proteins), SIgA (secretory IgA) and mucins bind bacteria through glycosylation > then they aggregate. It is then easier to remove these via swallowing.
- Lactoferrin, cystatins, histatins, lysozyme actively kill bacteria
Which proteins actively kill bacteria in saliva? (4)
Lactoferrin
Cystatins
Histatins
Lysozyme
If teeth are left in water, they would eventually dissolve - how does saliva combat this?
By having high levels of calcium and phosphate
Saliva is able to maintain high calcium and phosphate levels in solution
Why does saliva require chelators?
What are 2 examples of these?
This is to prevent high levels of CaP precipitating - as calcium and phosphate like to bind to each other.
Statherin and acidic PRPs
How do components of saliva bind with teeth? Why is this important?
Via their phosphate groups binding with the calcium in teeth/hydroxyapatite
(Statherin, acidic PRPs and histatin 1 bind as they all contain phosphate groups)
This is important because it is important in forming a stable pellicle of proteins on the teeth surface
What is the approximate size of the surface area of the mouth?
~ 200-400cm2
What is the approx film thickness of saliva in the mouth?
How is saliva able to cover so much surface area?
0.01- 0.001 mm
Because it has a low surface tension so can spread easily over mucosa and teeth
Where is saliva film velocity the fastest?
Next to ductal openings
If saliva film is moving fast, what are the implications of this?
Faster moving film means a greater exchange but urea causes pH to rise - this leads to ‘brushite’ formation and calculus
What is Stephan’s curve?
The Stephan Curve is a graph that shows what happens after the consumption of sugar in relation to dental caries. After sugar intake, demineralisation of the tooth surfaces takes place due to the drop in pH as the bacteria in the mouth convert the sugar to acid. (i.e. it shows the buffering effect of saliva)
What does bicarbonate do?
It ‘mops up’ acidity i.e. hydrogen ions/protons
Outline the formula in which bicarbonate clears acid/hydrogen ions from the mouth?
H+ + HCO3- (bicarbonate) > H2CO3 (carbonic acid) > carbon dioxide + water
(carbonic acid used carbonic anhydrase 6 enzyme to convert to CO2 and water)
CO2 lost when we breathe
What are the effects of increased flow rate? (5)
- Increased clearance of sugars and acids
- Increased buffering by bicarbonate
- Increased bicarbonate increase pH
- Increased pH makes saliva more saturated with calcium (leads to calculus)
- More antibacterial proteins
What may make a person more susceptible to caries? (5)
Low salivary flow rate (e.g. over 65s, xerostomia etc)
Foods with high levels of sugar/fermentable carbohydrate/liquid/acidic (encourages dissolution of enamel)
Regular snacking
Low salivary bicarbonate/urea/CaP levels
Poor oral hygiene (snacking during night).
