4. Prevention Of Caries By Saliva Flashcards
LOs
Static and dynamic effects of preventing caries
Static Effects
* No flow rate of saliva produces static effects on caries prevention on teeth
* They have antibacterial effects
* They are supersaturated with calcium and phosphate
* Formation of a salivary film across teeth is known as acquired pellicle formation
* Saliva also has some substrates for bacteria (plaque formation)
Dynamic Effects
- saliva moves
* Buffering effects of bicarbonate in saliva increases with increased salivary flow (buffering capacity changes with flow rate)
* Main effect is clearance of sugars and acids - prevents caries
* Supersaturation also increases with increased flow (of Ca2+)
3 pairs of major salivary glands
(lateral view image)
- submandibular
- just under jaw bones - sublingual
- just under tongue - parotid
- largest
- near ears
how many minor salivary glands are there
- hundreds of them all around the oral mucosa (hard palate, lip, etc)
- Percentage contributions of each gland to whole mouth saliva
- flow rates?
- 2 flow rates
At rest (0.2-0.5 ml/min)
- Parotid 20
- Submandibular/
- Sublingual 70
- Minor glands 10
Stimulated (1-2 ml/min)
- Parotid 60
- Submandibular/ 35
- Sublingual
- Minor glands 5
- hard to quantify sublingual and submandibular separarately
saliva protein profile
- probably over 1000 different proteins in saliva
ions in parotid saliva
- how is saliva made?
- important ions in parotid saliva?
1.
- making saliva is osmotically driven process
- to make saliva, lots of sodium and chloride ions are secreted into ducts that lead into the mouth
- this helps to draw water by an osmotic process
- secreting ions attracts water
(more detail in later lecture)
2.
- sodium
- chloride
- bicarbonate ions
- calcium
- phosphate
In the image…
* At rest, phosphate is greatest in amount
* Upon stimulation, sodium, chloride and bicarbonate
concentration increases
* Calcium and phosphate concentration does not
change much with flow rate
modifications of ions in saliva
- acinus
- striated duct
- Sodium, chloride and bicarbonate are reabsorbed whereas potassium is secreted into the striated duct
- Calcium is thought to enter saliva through cellular channels or bound to mucin in saliva
- acinus
make saliva - striated duct
modifies saliva
EXTRA Q FROM AZ NOTES
why can we taste tears and blood?
- We can taste tears and blood because the salt has been reabsorbed therefore our taste buds have become adapted to the non-salty environment
Bacteriostatic effects of saliva
- Bacteriostatic chemicals prevent bacteria from multiplying rather than killing them
- Bacteria like to bind to sugar as it can help drive their metabolism
- Many Proline Rich Proteins (PRPS), Secretory IgA’s (antibodies) and mucins bind bacteria through glycosylation
- They then agglutinate and are removed by swallowing
Bactericidal (kill bacteria) effects of Saliva
Bactericidal (kill bacteria) effects of Saliva
* Lactoferrin has an iron binding ligand within the centre
* It binds the iron with bacteria to prevent it from multiplying
* Cystatins and histatins are also found in saliva
* Lysozymes actively kill bacteria
Supersaturation of Saliva
* Saliva is supersaturated compared to enamel
what does this mean?
- Teeth left in water for a long time would dissolve
BUT
saliva prevents this with high levels of calcium and phosphate - However, saliva requires chelators (calcium binding proteins) to prevent high levels of calcium phosphate precipitating to form plaque (bind and stabilise Ca is sol so does not bind to phosphate.
- EG of chealators
- Why they’re important
- EXTRA FROM AZ NOTES
- 1.
- Statherin, acidic PRPs and histatin 1 are the main chelators which all contain a phosphate group
2. - These proteins are important in forming a stable pellicle of proteins on the surface of the tooth
3. - The dental pellicle, or acquired pellicle, is a protein film that forms on the surface enamel by selective binding of glycoproteins from saliva that prevents continuous deposition of salivary calcium phosphate. - It forms in seconds after a tooth is cleaned or after chewing.
dynamic effects of saliva on teeth (saliva film)
(think of more Qs)
- saliva only enters mouth when you’re awake
what is Stephan’s curve?
Effect of saliva on Stephan’s curve?
main buffering mechanism within saliva?
- Urea to ammonia, fasted plaque pH can be
higher than saliva due to bacterial urease, more important at lower flows
