Materials Final

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Materials Final
2013-04-28 16:54:56
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  1. What are the two types of flexible impression materials?
    • Hydrocolloids
    • Elastomerics
  2. What is the reversible hydrocolloid?
    Agar (no bowl needed)
  3. What is a model used for?
    It's a replica to Study oral anatomy.
  4. What is a cast used for?
    Working replica used for fabricating appliances.
  5. What is a Die used for?
    Working replica of one tooth used.
  6. Which impression material has the least amount of detail?
  7. What is the weakest part of a dental bridge?
    The cement
  8. How does dental Amalgam set up?
    By crystallization
  9. How does impression material set up?
    By Polymerization
  10. What comes out of gypsum pancakes and what is used for?
    Gauging water and it's just a lubricant
  11. What is the One rule for dental materials?
    Don't Assume Anything!
  12. How do you remove Alginate?
    With a snap
  13. What are thermal conductors?
    Metal things
  14. What is wetability?
    Resistance to flow
  15. Which material do you Vacuum form?
  16. What is used to polish a gold crown?
    Jeweler's Rouge (iron oxide)
  17. Which liner is universal?
    Ca(OH)2; calcium hydroxide
  18. Who does OSHA worry about?
    The workers
  19. Does Alginate shrink?
    Yes; syneresis
  20. How do you mix alginate?
    To a homogenous mixture.
  21. How dental implant placed?
  22. A secondary container needs to be used when and have what?
    After 8 hours; needs a label that is xeroxed or handwritten.
  23. Which Impression do you do first and why?
    Mandibular first, less likely to gag.
  24. Who provides the MSDS and what does it stand for?
    The manufacture provides and it stands for Material Safety Data Sheet.
  25. Who and when do you need hazardous training?
    New employees, if there are any changes it directions, and when there is new products introduced.
  26. Gypsum is what type of dental material?
    A ceramic
  27. How do you place Composites?
    They shrink is must place in increments
  28. What material is used for denture to be placed on a Low Alveolar Ridge?
  29. For dentures what material is used for a High Alveolar Ridge?
  30. Which cement is NOT used under composites?
  31. When trimming models what do you start with?
    The Maxillary Arch
  32. Can age determine whitening?
  33. When mixing liquid/powder ratio depends on what?
    intended use and manufacture instructions
  34. True or False. With Dental Material you want thermal conductivity.
  35. Define Retention
    Capacity of restorations & replacements to stay firmly in place.
  36. Define Adhesion
    Force that causes Unlike molecules to attach.
  37. What is Cohesion?
    Attraction of same kind of molecule.
  38. What is Tensile Force?
    The force moving away
  39. What is compression?
    The forces moving into the object
  40. Define Ductility
    Tensile stress w/o fracture
  41. Define Percolation
    Bubbling of fluids between solids.
  42. What is casting?
    Shaping by melting and forming
  43. What is wroughting?
    Shaping by twisting or bending
  44. What is Gypsum?
    A mineral CASO4 x 2H2O (calcium sulfate dihydrate)
  45. What are the steps to mixing and pouring gypsum?
    • Step 1: 50ml of water in a bowl and sift 100g of plaster and let sit of 5 seconds
    • Step 2: wet all powder and then spatculate until homogenous mixture
    • Step 3: Zing zing on the vibrator 
    • Step 4: Pour in one corner using the same corner each time you add some while zinging it on the vibrator.
  46. Characteristics of Plaster
    • Dry calcined hemihydrate, beta hemihydrate 
    • Crystals: spongy, porous, irregularly shaped. 
    • Low strength 
    • Low abrasion resistance 
    • Increased gauging H2O
  47. How do you alter the setting time of Alginate?
    By using cold water to slow it down and warm water to speed it up.
  48. What materials have a Exothermic Reaction?
    • Plaster
    • Stone
    • ZOP
    • PMMA
  49. Characteristics of Stone
    • Autoclaved hemihydrate 
    • Alpha hemihydrate 
    • Crystals: Prism shaped,denser 
    • Higher strength 
    • Higher hardness               
    • Less gauging H2O
  50. Characteristics of High Strength Stone
    • Densite, Modified Alpha- Hemihydrate 
    • Dense 
    • Stubby 
    • Crystals: Spheres, cubes 
    • Least H2O added
  51. How does plaster and stone set up?
  52. What are some plaster accelerators?
    Salt and K2SO4
  53. What are the plaster retarders?
    Borax, cold water, and citrate
  54. What are abrasives?
    Hard particles that abrade a softer surface (substrate).
  55. MOH Scale
    • Measures Hardness
    • Diamond 10
    • Al2O3 9
    • Porcelain 6-7
    • Tin Oxide 6-7
    • Pumice 6
    • Rouge 5-6
    • Composite 5-7
    • Enamel 5-6
    • Gold Alloy 3-4
    • Dentin 3-4
    • Gypsum 2
    • Acrylic 2-3
  56. If you increase the liquid/powder ratio of cement it's what?
    More soluble, less strong.
  57. What part of an implant protect from bacteria?
    periomucosal seal
  58. What is one thermoplastic?
    Gutta Percha
  59. Base Metals
    • CO-Cr
    • Cr-Ni
    • stainless steel
    • Ti
  60. Noble metals
    • —Gold 
    • —Platinum 
    • Rhodium
  61. Amalgam with Cu
    Gives High strength, resistance to corrosion, and hardness
  62. Amalgam with Ag (silver)
    High Luster
  63. Amalgam with Sn (Tin)
    Reduces expansion, strength, hardness, and WORKABILITY
  64. Amalgam with Zinc
  65. Bonds can be what?
    • Composites
    • Veneers
    • Sealants
  66. True or False: Titanium is a reactive material, but not in the body.
  67. What are some ceramics?
    • Porcelain
    • Zinc Oxide
    • Glass ionomers
    • Silica: SiO2
    • Kaolin
    • Zirconia
  68. Which cements bond to the tooth?
    • Glass ionomer
    • Polycarboxylate
  69. ZOP
    • Permanent Luting Agent
    • Thermal Insulating Base under deep amalgam restorations
  70. ZOE
    • Uses include Base, Temporary Luting , Temporary Restorations.\
    • Soothing, OBTUNDENT to pulp
  71. Polycarboxylate
    • Not as strong as ZOP 
    • Less irritating that ZOP
    • Bonds to the tooth
  72. Glass Ionomer
    • Used as permanent luting and permanent restorations( comes in blendable shades) 
    • Fluoride leaches out of the powder into the tooth structure 
    • Chemically bonds to tooth structure (bonds to Ca++ in the tooth)
    • Used for lots of things
  73. Intermediary Materials
    Materials placed between the tooth and the main restorative material
  74. What is the most commonly used Liner?
  75. What are varnishes used for?
    Seal dentinal tubules
  76. Polysulfide aka Mercaptan
    • Smells strong.
    • Pour ASAP or at least within 30 min.
  77. Polysiloxane
    Should be poured ASAP
  78. Polyvinyl Siloxane
    • Cannot wear latex gloves because contact may retard the setting time of the vinyl.
    • Should be poured within 2 week
  79. Polyether
    Should be poured within 2 week period