Dental Materials

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Author:
sthomp88
ID:
68264
Filename:
Dental Materials
Updated:
2011-03-23 23:36:42
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chapter six
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week six
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  1. What are the 4 most commonly used direct-placement esthetic materials?
    • composite resin
    • glass ionomer cement
    • resin-modified glass ionomer ( or hybrid ionomer)
    • compomer
  2. a mixture of two or more materials with poperties superior to any single component
    composite
  3. tooth-colored materials that are used in both the anterior and posterior parts of the mouth
    composite resins
  4. What are the 3 things that composite resins are mostly composed of?
    • organic resin (polymer) matrix
    • inorganic (silica) filler particles
    • joined together by silane coupling agent
  5. What is the most commonly used resin for the matrix of composites? What is another resin that is used for composite matrix?
    • bis-GMA
    • bisphenol-A
  6. What does the addition of filler particles do to the organic resin?
    makes it stronger and more wear resistant
  7. true or false. Fillers are also added to resin to control the handling characteristics of the composite resin and to reduce the shrinkage that occurs when the resin matrix polymerizes or sets
    true
  8. What are the fillers used in composite resins?
    inorganic silica particles
  9. What are two ways that silica may be used in?
    • crystalline form - quartz
    • noncrystalline form - glass
  10. What are 5 materials that are used to make the composite resin restoration show up on radiographs? (radiopaque)
    • ions of:
    • barium
    • strontium
    • boron
    • zirconium
    • yttrium
  11. What is used to provide a stronger bond between the organic fillers and the resin matrix?
    coupling agent
  12. What coupling agent is used in resins?
    silane
  13. What are the 4 main purposes of filler components in composite resins?
    • make organic resin stronger
    • more wear resistant
    • control handling characteristics
    • reduce polymerization shrinkage
  14. The higher the amount of filler content in a composite material=?
    stronger and more wear resistant
  15. Why do we want smaller filler particles on the resin surface?
    • because smaller filler: cause fewer voids that contribute to wear
    • be packed closer together
    • smoother surface
  16. What 2 things is good adhesion of the two coupling agents necessary for?
    • to minimize loss of filler particles
    • and to reduce wear
  17. monomers join together to form what?
    polymers
  18. Which type of cured composite resin are two-paste systems supplied in jars, syringes, or cartridges? (self-cure)
    chemically cured
  19. What are the two 'pastes' in chemically cured composite resins?
    base and catalyst
  20. What material makes up the base in chemically cured composite resins?
    • composite
    • benzoyl peroxide=initiator
  21. What material makes up the catalyst in chemically cured composite resins?
    • composite
    • tertiary amine=activator
  22. What is the working time for chemically cured composite resins before it becomes too stiff to manipulate?
    2 minutes
  23. What are the most common type of composite resin used in private practice?
    light-cured composites
  24. What is it called wen side groups of adjacent polymer chains share electrons, form COVALENT bonds that link the chains together?
    cross-linking
  25. In general it is recommended that the composite be placed in increments no thicker than __ mm when using light-cured composite
    2mm
  26. Why do interproximal areas need to be cured longer with the light-cure composite?
    because of the more difficult access of the area to the direct path of light
  27. Do lighter or darker shades of composite need more light curing time? Why?
    • darker
    • the light is more readily absorbed by the dark color, and does not transmit through the material as readily as through light-colored materials
  28. What has helped make composite restorations more durable, leak less, polish better, and match the teeth better?
    • over time: filler particle size has become smaller and smaller
    • number of fillers in resin has increased
    • polymerization shrinkage has decreased
  29. What type of material contains both macrofillers and microfillers with filler particles ranging from .1-3 micrometers? Which is why it has this name?
    hybrid composites
  30. the combination of macro and microfillers in hybrid composites produces what?
    a strong composite that polishes well
  31. What are the particle sizes in nanohybrids?
    .005 to .020 micrometers
  32. shrinkage has been reduced from __% with earlier composites to less than __ % with some of the nanohybrids
    • 3
    • 1
  33. What type of composites are strong composites that can be polished to a high shine, and they retain that shine better than earlier composites?
    nanohybrids
  34. LOW-viscosity, light cured resins that may be lightly filled, or more heavily filled
    flowable composites
  35. true or false. nano-sized fillers are being used in flowable composites now also
    true
  36. ______ composites are well suited for use in conservative dentistry (preventive resin restorations), where they readily flow into the narrow preparations created with small burs and diamonds or air abrasion. They may be used in place of pit and fissure sealants.
    flowable
  37. Why are flowable composites more wear resistant than that of most lightly filled sealants?
    because their filler content is higher
  38. Why are flowable composites so useful as liners in large cavity preps?
    because they adapt to the preparation better than more viscous materials such as hybrid and packable composites
  39. What allows flowable composites to cushion stresses created by polymerization shrinkage or heaby occlusal loads when they are used as an intermediate layer under hybrid and packable composites?
    their low elastic modulus
  40. flowable composites are useful for restoration of class _____ noncarious lesions caused by toothbrush abrasion, acid erosion, or occlusal stresses such as bruxing that lead to flexing of the tooth
    V
  41. Why aren't flowable composites used in areas of high occlusal function or high wear?
    because they shrink more when polymerized, wear more readily, and are weaker than hybrids

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