gda.txt

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gda.txt
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2012-05-15 09:39:41
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  1. What is a succedaneous tooth? Which teeth are non-succedaneous?
    A tooth that ‘succeeds’/replaces a deciduous tooth. All permanent molars i.e. 1-3, 14-19, 30-32
  2. Enamel and oral epithelium are derived from?
    Ectoderm
  3. Dentin, Pulp, Cementum, PDL, and Alveolar bone are derived from?
    Ectomesenchyme
  4. What is the order of the Stages of Tooth Development?
    • Bud, Cap, Bell,
    • Dentiongenesis, Amelogenesis,
    • Crown Formation, Root Formation and Eruption,
    • Root completion
  5. What is the thickening of Oral epithelium that precedes the bud stage? What dental abnormalities would originate at this stage?
    Dental Lamina. Hyperdontia (supranumerary teeth), hypodontia (if no buds form)
  6. What germ layer guides tooth formation?
    Ectomesenchyme
  7. What represents the basement membrane in the fully developed tooth?
    The DEJ
  8. How many layers does the Enamel Organ differentiate into and what are they?
    • 4: Outer Enamel Epithelium (OEE), Inner Enamel Epithelium (IEE) these two layers are actually continuous
    • Stellate Reticulum, Statum intermedium
  9. What do the cells of the Inner Enamel Epith (IEE) differentiate into and what is the change in shape?
    IEE (cuboidal)  ameloblasts (columnar)
  10. What do the outer cells of the Dental papilla differentiate into?
    Outer cells of Dental Papilla  Odontoblasts
  11. Does dentin or enamel get formed first?
    Dentin
  12. What are the processes on Odontoblasts and Ameloblasts called, and which is longer?
    Odontoblastic processes (longer), Tomes’ process
  13. Are Odontoblasts and Ameloblasts polarized? Which side is their nucleus towards and why?
    Yes. Nuclei are on the side further from DEJ - more room at the trailing end for secretory vesicles to deposit predentin or enamel matrix.
  14. What are organelles required by a secretory cell ie. an odontoblast?
    Golgi, Matrix vacuoles (contain Ca and P), Mitochondria, Rough ER, a nucleus
  15. What feature of dentin is a result of the odontoblastic processes?
    Dentinal tubules
  16. Does mineralization of enamel, dentin, and cementum happen intracellularly or extracellularly?
    Extracellularly
  17. Tetracycline staining occurs during what process?
    During Calcification of tissues
  18. What causes preameloblasts to mature into ameloblasts?
    Predentin
  19. What is the order of enamel and dentin deposition?
    Predentin  the first of the enamel matrix  dentin calcification  enamel calcification
  20. Where is the oldest enamel and dentin?
    Closest to the DEJ, closest to the cusp tip. (see slide 24)
  21. What two layers make up Hertwig’s Epithelial Root Sheath (HRS)? What is HRS’s purpose?
    OEE + IEE . Guides shape and number of roots
  22. What germ layer is HERS?
    Ectoderm
  23. What are Rests of Malassez? and what is a potential problem due to them?
    When the HERS cells die off at the future CEJ to allow cementoblasts access, some epithelial cells don’t die and instead get trapped in the resulting PDL = Rests of Malassez. Might become cysts (and require surgical removal)
  24. What happens if enamel and cementum don’t meet at the CEJ?
    (exposed dentin ) Hypersensitivity
  25. How and during what stage do Enamel Pearls form ?
    Root formation – ameloblasts at the CEJ didn’t get turned off and kept going.
  26. What layer in the crown portion of the tooth is the counterpart to HERS?
    Reduced Enamel Epithelium
  27. What might happen if the REE is dysfunctional or absent?
    Cementum might be formed on the enamel, Eruption might not happen, There might not be a Junctional Epithelium
  28. What is the repair potential of dentin, cementum, and enamel?
    • 1.dentin
    • 2. cementum
    • (3. enamel: none)
  29. How long does Tooth Eruption/Root & PDL formation take?
    2-3 years
  30. When do the following events happen? Buds form; migration of ectoderm into ectomesenchyme
    A: Bud stage
  31. When does Dental Organ proliferation into a cap shape, and the Condensation of the ectomesenchyme next to it to form Dental Papillae
    A: Cap stage
  32. When does the Dental Lamina disappear, the Enamel Organ differentiates into EDE and IDE, which proliferate and migrate apically, & the Dental papillae differentiates into pulp and odontoblasts?
    A: Bell stage
  33. Origin of pulp? Origin of Odontoblasts?
    NCC  neuroectochyme  ectomesenchyme  Dental Papilla -> pulp or odontoblasts
  34. Origin of Ameloblasts?
    IDE
  35. Constituents of Hertwig’s Root sheath?
    EDE + IDE
  36. What happens Late bell stage*?
    Root formation starts. (but not the main process until after crown formation)
  37. What is the main process of the Crown stage?
    Mineralization.
  38. What is the mechanism of odontoblast and ameloblast maturation?
    Reciprocal Induction.
  39. What are the two cell types involved in reciprocal induction?
    Dental papilla cells, IDE
  40. Which forms first, dentin or enamel?
    Dentin
  41. What is the important growth factor for tooth development? Is it an extracellular or intracellular protein? What is its pivotal role?
    TGF-Beta. Extracellular (triggers intracellular events via surface receptor). Role: tooth development and repair.
  42. What are the important transcription factors for tooth development?
    Smads and Cbf-a (core binding factor A).
  43. What are the relationships of the cellular factors involved in tooth development?
    • TGF-b binds receptor  Smad (txn fctr) activated  Cbf-a (txn fctr) expression  osteogenesis and dentinogenesis
    • TGF-b is responsible for activating Smad high TGF-b production happens early, during lamina stage
    • Smad is responsible for the size and shape of tooth bud at a given time during bud stage
    • also responsible for promoting Cbf-a expression
    • smad mutant: abnormal size and shape
    • Cbf-a is responsible for osteogenesis and dentinogenesis (and tooth development)
    • Cbfa mutant: lose morphology
  44. What do you call the opening of the pulp (root) canal
    • at the chamber/coronal side? Orifice
    • at the apical side? Foramen
  45. Which part of the pulp has dentin, predentin, odontoblasts, dendritic cells, and a Cell-free and Cell-rich zone which contain nerve and capillary plexuses? What type of cells does the cell-rich zone contain?
    Peripheral Pulp. Some fibroblasts, and undifferentiated mesenchymal cells.
  46. Which part of the pulp has mostly fibroblasts, large vessels and nerves and resembles Connective tissue?
    Central Pulp
  47. What is the difference between predentin and dentin?
    Dentin – unmineralized. Dentin – mineralized with HA.
  48. Which cells are found in normal pulp?
    T cells, Macrophages
  49. Which cells are not found in normal pulp?
    B cells, PMNs
  50. If you find PMNs in pulp, what does that indicate? B Cells?
    PMNs = there is acute inflammation. B cells = there is Chronic inflammation.
  51. What is the purpose of macrophages/monocytes? Function of dendritic cells?
    Macrophage – Phagocytosis. Dendritic cell - Antigen presentation
  52. Which cell type produces collagen type I, and where do you find it?
    Odontoblasts. Found in predentin and dentin
  53. Which cell type produces collagen type III, and where do you find it?
    Fibroblasts. Found in pulp
  54. A PARL (periapical radiolucency) is a result of what?
    Destruction of bone around the root. It is a sign of chronic root infection.
  55. Why does inflammation in the pulp lead to necrosis?
    The pulp cavity is a non-compliant space; it doesn’t expand. Thus, pressure increases, and blood flow into pulp is compromised which results in necrosis.
  56. Why are AVA shunts (from arterioles to venules) important? Will they work during chronic inflammation?
    • Allows limited blood flow when one part is blocked due to mild-moderate inflammation.
    • No. vasculature in chronic inflammation is completely compromised.
  57. Is dentin permeable to microbes? Why?
    Yes, due to dentinal tubules
  58. Are Conventional Root Canal Therapies (including re-treats) VERY successful? Success rates?
    • Yes. 1st time 94-99%, overall ~91%.
    • Retreat 83%
  59. Is MTA Pulp capping a good option? Pulp survival rate?
    Yes. 98%
  60. What gives dental pulp its regenerative capacity?
    Dental Pulp Stem Cells (DPSCs). Even greater regenerative capacity than bone marrow cells.
  61. Are there stem cells elsewhere?
    • Yes – PDLSC (periodontal ligament stem cells)
    • SHED (stem cells of human exfoliated deciduous teeth)
  62. What do you find in immature root apices?
    • SCAP – stem cells of apical papillae.
    • They become odontoblasts which will make dentin at the root.
  63. Even in necrotic pulp, could there be viable apical stem cells to complete root formation after treatment?
    Yes.
  64. Bio-root tissue engineering was done on what animal? Was the artificial dentin as strong as natural dentin?
    Mini-pigs! No.

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