Prevention of Caries by Saliva Flashcards
What is meant by the static & dynamic effects of saliva?
Static - Saliva is just present and not moving around
Dynamic - Saliva is moving over tooth surfaces
What are the static effects of saliva?
-Antibacterial
-Supersaturated Ca/P
-Pellicle formation (acquired enamel pellicle- layer of protective proteins which sit on the tooth’s surface)
-Plaque substrates e.g Urea
What are the dynamic effects of saliva ?
-Buffering (bicarbonate increases with flow)
-Clearance of sugars and acids
-Supersaturation (increases with flow)
How effects do plaque substrates have?
-Urea can be converted by Urease into ammonia.
-Ammonia helps to maintain High pH
-High pH is useful when buffering acids
What is specific to each gland?
Salivary protein profile
look at the slides
What percentage does each salivary gland contribute to whole mouth saliva?
At rest, the submandibular/sublingual gland contributes the most.
When stimulated, the parotid gland contributes the most.
How is saliva made?
By an osmotic driven process
-Salivary glands secrete lots of sodium & chloride into the ducts that lead into the mouth & this helps to draw water by an osmotic process
What are the 2 main types of cells and what do they do?
Acinus : make the saliva
Striated Duct : modify it
look at the slides
How do the ion concentrations in parotid saliva change?
When going from a resting to stimulated state,
Na+, Cl- and HCO3- concentration increases
Phosphate and Ca2+ stays relatively the same
look at the slides
How does saliva have a bacteriostatic effect?
Saliva has many PRPs, SIgA & mucins which bind bacteria through glycosylation, then aggregate and it’s removed by swallowing (maintains bacterial levels = Bacteriostatic)
On the other hand, lactoferrin, cystatins, histatins & lysozyme actively kill bacteria
What does it mean to say saliva is supersaturated compared to enamel?
If teeth were left in water, they’d dissolve
-Whereas saliva has high levels of Ca2+ & phosphate to prevent this,
-BUT saliva requires chelators to prevent high levels of CaP precipitating- statherin & acidic PRPs
Which proteins are important in forming a stable pellicle of proteins on the surface of teeth?
Hydroxyapatite binding proteins e.g. statherin, acidic PRPs & histatin 1 (all contain phosphate groups).
How is saliva able to form a thin film over all of our teeth (this is a dynamic effect)?
It has quite a low surface tension & can spread easily over the mucosa & also the teeth
It’s also constantly moving, with the film velocity being fastest next to ductal openings
What happens at the location where the film is the fastest?
-That’s where there is the greatest buffering due to urea causing rise in pH
-But one of the side effects is that’s where you find the greatest accumulations of calculus
What is the reason for finding the most calculus where the film moves the fastest?
In those areas, the pH always stays very high so that it never gets dissolved away.
