biochem friday sessions

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biochem friday sessions
2013-02-18 21:49:24
biochem friday sessions

biochem friday sessions
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  1. The major threat to teeth is?
  2. The major threat of teeth is typically done by ?
    acid challenges
  3. To counter threat DISSOLUTION by ACID CHALLENGES, what 2 things ?
    1. Teeth are made at VERY LOW SOLUBILITY mineral called HYDROXAPATITE SALTS aka "spongy soluble."

    2. Surrounding fluids are going to PROTECT from mineral loss.
  4. equilibria=?
  5. Product= Ksp, which is defined as the...
    IP @ equilbria
  6. The lower the Ksp...
    the LESS SOLUBLE/ MORE STABLE the salt
  7. CaF2 is what compared to AgCl?
    less soluble
  8. Tooth mineral hydroxyapatites are much more complex for 2 reasons:
    • 1. Variability in combinations of Ca/PO4/OH
    • 2. Other ions "impurities" can be present
  9. Pure hydroxyapatite at Ksp?
    Ksp 10^-59
  10. Ksp of pure complex salt hydroapatite when you subsititue F-
    Ksp 10^-61
  11. Formation of TOOTH MINERAL done in presence of other ions that become____.
    incorporate air impurities
  12. Most common impurity is?
    carbomate Co3 2-
  13. Carbomate does what ?
    • -destabilizes HA crystals
    • -this means it increases solubility, and increases KSP
  14. Biological apatite:

    Contains "contaminating ions" that can have a major effect on crystal stability , thus solubility,
    + or -, see table
  15. Most common subsitutions are?
    carbomate and fluoride
  16. Most common substations, carbomate & fluoride, result in enamels apatite being primarily a ?
    carbonated flurohydroxyapatite with an estimated Ksp of 10^-58
  17. Fluoride does what to teeth?
  18. In tooth apatite, which is more prevalent carbomate or fluoride?
  19. Ksp apatie =
    • 10^-58 TOOTH KSP,
    • -1/10 as stable as pure hyrdoxapatite
  20. When do we use IP?
    when we ar NOT at equilibrium

    **we only use Ksp when we are AT equilibrium
  21. Why is precise Ksp impossible to determine?
    bcuz of its variable composition
  22. The principle behind protection of teeth by ions is in the ?
    surrounding fluids
  23. AgCl example: adding Common Ion Cl-
    shifts the equilibrium back to the solid according to LE CHATLIERS PRINCIPLE OF MASS ACTION
  24. IP> KSP shifts ?
  25. If IP>Ksp what happens to the solid?
    remineralization of the solid occurs
  26. In the Common Ion Effect:

    -The solution is said to be?
    super saturated, which is Cl here
  27. The common ion effect in the mouth is a ?
    anti-cariogenic effect of salivary salts
  28. Fluids bathing the teeth contain
    Calcium ions, Phosophate ions, Hydroxylate ions, and others

    -not derived from the tooth mineral but other exogenous sources
  29. Ca, P, ion concentrations significantly affect the IP of the fluid, & thus the what of the tooth mineral?
  30. The supersaturation of fluids with HA salts does what?
    MAXIMIZES tooth remineralization & LIMITS tooth demineralization
  31. Generalized demineralization of the teeth is known as?

    -caused by general acid in saliva
  32. Localized demineralization is from?
    plaque bacteria produced acid , IT INIATIATES CARIOUS PROCESS
  33. Saliva promotes?

    **This is a MAJOR PROTECTION MECHANISM, the Common Ion Effect
  34. 2 ions that are PH dependent?
    PO3 4- and OH-
  35. PO4 3- decreases with?
    decreasing PH
  36. AS H+ increases in PH, OH- ?
    decreases in PH
  37. The most common apatite impurity does what with decreasing pH?
    carbomate, it also decreases
  38. AS pH drops, what does Ip do?
    IP decreases
  39. The PH at which IP=Ksp is called?
    Critical pH and is 5.5
  40. At ph's below the critical ph, the oral fluids are ?

    -the HA ionization equilibrium shifts to the RIGHT resulting in demineralization of the tooth
  41. Keq is?
    relationship between Ksp to Ip
  42. If IP is high, we have LOTS OF COMMON IONS which promote?
    remineralization of the tooth