Dental Materials

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Dental Materials
2011-03-25 08:40:53
chapter eight

for test two
Show Answers:

  1. What is the most common restoration in fixed prosthodontics?
    Porcelain-metal restorations (PBM/PFM)
  2. What is the main advantage of the porcelain-metal restorations?
    the strength of the restoration from the bond between metal and porcelain
  3. What is it that forms the strong bond between the metal and the porcelain of PBM/PFM restorations?
    As the metal is heated it forms an OXIDE layer, when the porcelain is applied to the metal, the porcelain chemically fuses to the oxides on the metal
  4. What are most porcelain failures related to?
    the chemical bond between porcelain and OXIDES upon occlusal loading
  5. How thick is the metal used in PBM/PFM restorations?
    pretty thin: 0.3-0.5 mm thick
  6. What type of crowns are low fusing porcelain?
    porcelain jacket crowns
  7. Is the fracture rate in the posterior due to occlusal loading higher in all ceramic or PFM crowns?
    all ceramic!
  8. Name 4 ways all ceramic crowns are used despite their fracture rate.
    • inlays
    • onlays
    • crowns
    • veneers
  9. Name 2 advantages of using low fusing porcelain over regular porcelain.
    • less wear (less abrasive) on opposing teeth
    • easier to polish
  10. What is an advantage of low fusing porcelain to PFM?
    there is no need for an opaque layer to mask the metal
  11. What are 2 main advantages of computer assisted -CAD/CAM restorations?
    • no die and no temporary crown needed
    • optical scanner makes 'impression' of the crown prep and adjacent teeth
  12. Name 3 purposes for veneers
    • lighten teeth
    • cover defects such as dark teeth - so they are more opaque
    • close diastemas
    • reshape crooked teeth (look like they had orthodontics)
  13. Do veneers bond better to enamel or dentin?
  14. What is added to veneers to enhance the bond between porcelain and resin cement?
    SILANE coupling agent added to ETCHED porcelain surface
  15. how are veneers 'conditioned'?
    with hydrofluoric acid
  16. You should take the shade of the tooth __________ the tooth prep and ________ placement of rubber dam
    • before
    • before
  17. _____ is tooth color
    _______ is intensity of the color
    _______ is the lightness or darkness of the tooth
    • hue
    • chroma
    • value
  18. do dry teeth appear lighter or darker?
  19. fluorescent lights make the shade of the tooth look more _________. Incandescent lights make the shade of the tooth look more _________.
    • blue
    • yellow
  20. What is the best light to use in taking the shade of someones tooth?
    Natural North light
  21. The dental unit light increases _______________ and decreases ______________
    • shade brightness
    • color intensity
  22. true or false. It is best to use a neutral background color for matching the shade of a tooth; the pastel blue pt bib is fine.
    both are true
  23. What are 3 surface characteristics that are noted about shade when sending it in?
    • luster
    • transleusency
    • texture
  24. What type of fluoride should you use in the presence of any type of restoration?
    sodium fluoride!