5endo.txt

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Author:
Grant32
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186728
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5endo.txt
Updated:
2012-12-02 22:13:17
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endo
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Endo lecture 5
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  1. What are the three file types?
    • 1.Carbon steel
    • 2. Stainless steel
    • 3. Nicket titanium (what we use today)
  2. What is the taper of a nickel titanium rotary instrument?
    • For every mm, you increase .02mm
    • There is a .04 taper and a .06 taper
  3. Which hand and rotary instruments are lathe ground or machined?
    Hedstrom, most nickel titanium, and some K-files
  4. How are hand/rotary instruments ground and twisted?
    • Ground into square, triangular, or rhomboid blanks
    • Twisted counterclockwise to produce helical cutting edges
    • Have a pyramidal tip of 75 degrees or -15 after twisting that is rounded and non-cutting
  5. Which has more twists/mm, reamers or files?
    Files have more twists/mm
  6. File and reamer shapes
  7. How far do cutting flutes extend up to the tip of the file?
    16mm (Do-D16)
  8. What is the change in tip sizes?
    • Tip size increases by .05mm up to size #60
    • Tip size increase .10mm from #60-140
    • File diameter increases .02mm/mm of length (Do-D16=.32mm)
  9. What are the tapers on Nickel titanium instruments?
    .02, .04, .06, .08, .10
  10. Between which two file sizes is there the largest increase?
    between 10-15
  11. Which files are hand operated?
    • K-type files and reamers
    • Barbed broaches
    • hedstrom files
  12. Which files and reamers are engine driven?
    • Files and reamers (constant counterclockwise rotary motion
    • Files and reamers (reciporocates 90-180 degrees each way)
    • Gates Glidden- (#2,3,4)
  13. What are some aspects of carbon steel files vs. stainless steel?
  14. What is the torsional limit?
    Amount of rotational torque that can be applied to a 'locked' instrument to the point of breakage
  15. Which instruments have higher torsional limits?
    • Smaller instruments (<20) withstand more rotations than larger
    • Machined files deform more quickly
    • Nickel titanium files have increased resistance to fracture compared to stainless steel
  16. How do you avoid separation, unwinding, and roll-up?
    • Inspect instruments before each use
    • unwinding results from clockwise twisting
    • Roll-up results from counter-clockwise twisting
    • Instruments separate more easily in a counter-clockwise direction
  17. Nickel titanium rotary instruments
    • 50/50 combination of Nickel and Titanium
    • Very corrosion resistant
    • Superelastic, has shape memory
    • Has two reversible configurations (austenite and martensite)
    • More resistant to fracture than stainless steel and more difficult to pre-bend
    • Usually made by micromachining
  18. What are some features of the X-smart endo motor?
    • Speed and torque control
    • Auto-reverse
    • Able to program settings
  19. What RPM are Gates Glidden files set at?
    800 RPM
  20. What RPM are numbered files set at?
    300 RPM
  21. What does sterilization do?
    • Unlike disinfection, sterilization kills all organisms
    • They can't eliminate Prions
  22. What are the two types of sterilization?
    • 1. Pressure (steam and chemclave)
    • 2. Dry heat
  23. What are the settings for Steam sterilization?
    121 degrees Celcius and 20 psi for 30 minutes
  24. What are the operations for Chemclave?
    • Causes less rusting of steel instruments than steam
    • Uses alcohols, ketones, formaldehyde, and water
    • 127 degrees Celcius and 20 psi for 20 minutes
  25. Which dulls cutting edges faster, Pressure or Dry heat?
    Pressure dulls cutting edges faster
  26. What are the types of disinfectants?
    • Mostly phenolic
    • 70% isopropyl alcohol
    • Quarternary ammonium solutions
    • Sodium hypochlorite 5.25% to 6%
  27. What are the irrigants used today for canals?
    • NaOCl- Kills bacteria and dissolves necrotic tissue
    • EDTA- Kills bacteria and removes smear layer
    • Chlorhexidine- Kills bacteria with no tissue dissolution
    • Distilled water- only flushing and debris removal
  28. Action of sodium hypochlorite
    • Sodium hypochlorite 5% at 50 degrees C
    • Should be left in canals for a minimum of 10 minutes during treatment
  29. Calcium hydroxide
    • High pH (11-12)
    • Reduces bacterial colonization except enterococcus and actinomyces
    • Can dissolve necrotic tissue
    • Reduces toxic by-products
    • Placed by counter-rotated files, lentulo spirals or compaction of dry CaOH poweder
  30. What is the smear layer?
    • 1.Fragments of microscopic mineral crystals produced by instrumentation
    • 2.Organic debris
    • 3. Bacteria and by-products, viruses, fungi, yeasts
  31. Why do we want to remove smear layer?
    • Source of substrate for bacterial growth
    • Avenue for leakage
    • may prevent or delay disinfectant action
    • may interfere with sealer or gutta percha adhesion
  32. How is the smear layer removed?
    • Organic and inorganic acids
    • EDTA, RC Prep, 5-10% Citric acid
  33. Temporization

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