Dental Materials

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Dental Materials
2011-02-04 00:42:26
Chapter five

week three
Show Answers:

  1. What are BIS-GMA or urethane dimethacrylate?
    dentin resins
  2. How are dentin resins which establish micromechanical retention with enamel and/or dentin by adapting by adapting to relief areas created?
    by conditioning with phosphoric acid
  3. What does BIS-GMA stand for?
    bisphenol a glycidyl methacrylate
  4. What are the 6 steps of binding with dentin resins?
    • 20 second etch- enamel (dentin-10 second etch)
    • rinse
    • dry (leave dentin moist)
    • application
    • air thin
    • polymineralization
  5. Polymineralization is typically activated by what?
    fiber optic light
  6. light-activated polymerization allows flexible what?
    working time
  7. What are some common reasons for bonding failure?
    contamination by saliva or oils
  8. What is a good way to prevent contamination of saliva or oils?
    rubber dam
  9. What do you have to do if contamination at any step of the bonding process occurs?
  10. What term is used to describe the process of attaching restorative materials by adhesion?
  11. What is the first step in the bonding process?
    preparation of the surface of the tooth including removing plaque and debris
  12. How do you remove plaque and debris from the tooth surface in preparation for bonding?
    etching or conditioning enamel or dentin with acid
  13. What is the most commonly used acid in etching? And what does it do?
    • phosphoric acid
    • removes tooth mineral to create porosity
  14. What happens when a resin bonding agent or primer is flowed over the etched surface?
    it penetrates into the microscopic pores
  15. What happens when the resin bonding agent hardens?
    creates a mechanical bond called 'resin tags' that lock into the tooth (mechanical bond)
  16. What type of bond is a resin to resin or composite to resin?
    chemical bond or primary bond
  17. What type of bond is a true adhesion between atoms or molecules of the composite resin and the bonding resin?
    chemical bond
  18. true or false. the chemical bond is stronger than the weak physical bond
  19. acid etching increases the ability of liquids to wet the surface of the tooth by creating a _________
    high surface energy
  20. good __________ increases the intimate contact of the bonding resin with the etched tooth structure, improving the penetration of resin to form tags and thereby improving the bond
  21. What helps to attract the resin to the etched surface?
    high surface energy
  22. surfaces that are poorly wet will cause what?
    beading of the liquid
  23. Etching of enamel removes a small portion of the __________, reduces the ends of the _________ __________, and opens _________ between adjacent rods
    • surface
    • enamel rods
    • porosities
  24. What is the optimal time for etching?
    20-30 seconds
  25. What type of teeth may require up to 60 seconds of etching?
    highly mineralized teeth such as fluorosis
  26. How long should you etch primary teeth?
    60 seconds
  27. Why do primary teeth have to be etched for longer amounts of time?
    because the surface of the enamel has a prism pattern that is not as well structured, it is aprismatic
  28. What is the recommended rinsing time for acid etch gels?
    10 seconds or longer
  29. true or false. rinsing time for liquid etch can be shorter, like 5-10 seconds
  30. Does dentin or enamel have a higher water and organic content?
  31. What are 3 components of dentin?
    • collagen matrix
    • mineral (hydroxy appetite)
    • dentinal tubules
  32. layer formed when a cavity preparation is cut with rotary or hand instruments, a layer of cutting debris forms on the surface of the cut dentin and enamel
    smear layer
  33. why does dentin need to be etched for a shorter amount of time than enamel?
    because enamel is more highly mineralized
  34. How long should dentin be etched?
    10 seconds
  35. What happens if you etch dentin for too long?
    • opens dentinal tubules too wide and removes hydroxyapatite mineral to too great a depth
    • It decreases bond strength and increases hypersensitivity
  36. What happens if the dentin is dried too much during the dentin acid process?
    collagen fibrils collapse and form a dense surface that occludes the tubules and blocks adequate penetration by the dentin bonding resins
  37. ___________ are low-viscosity resins that flow well into the microscopic porosities and irregularities of the etched surfaces
    bonding agents
  38. agents bonding to what material alone requires only a low-viscosity liquied resin monomer that will penetrate into the spaces on and between __________ _________ created by acid etching
    • enamel
    • enamel rods
  39. What allows resins to penetrate water on the dentin and in the dentinal tubules and to penetrate around collagen fibrils and into porosities in the tooth surfaces created by etching?
  40. aceton, ethanol, or a combination of ethanol and water are what?
  41. What are the 2 components of dentin bonding agents?
    • resin primer
    • resin adhesive
  42. Which resin penetrates etched dentin and enamel and is a mechanical bond?
    resin primer
  43. which resin bonds chemically to the primer?
    resin adhesive