Dental Restorative Materials: Polymerization Shrinkage
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Questions and Answers

What is the result of inadequate packing pressure on the mold?

  • Improved coefficiency of thermal contraction
  • Irregular voids on the surface of the denture (correct)
  • Uniform polymerization of the acrylic dough
  • Increased polymerization shrinkage

    • What is the effect of residual monomer on the denture?

  • It makes the denture weaker and more flexible (correct)
  • It has no effect on the denture's properties
  • It makes the denture stronger and more rigid
  • It increases the denture's optical properties

    • What is the primary cause of contraction or shrinkage porosity on the surface of the denture?

  • Insufficient dough packed in the mould (correct)
  • Packing before the dough stage
  • Underpacking of the material
  • Overpacking of the material

    • What is the purpose of packing excess acrylic dough?

    <p>To decrease polymerization shrinkage from 7% to 0.2%</p> Signup and view all the answers

    What is the consequence of under curing the acrylic resin?

    <p>High residual monomer in the denture</p> Signup and view all the answers

    What is the result of exceeding the boiling temperature of the resin during polymerization?

    <p>Gaseous monomer is formed</p> Signup and view all the answers

    What is the effect of polymerization on the material's volume?

    <p>It decreases the material's volume</p> Signup and view all the answers

    What is the result of overheating the acrylic resin during curing?

    <p>Formation of gaseous porosity</p> Signup and view all the answers

    What is the purpose of ensuring sufficient dough is packed in the mould during denture base manipulation?

    <p>All of the above</p> Signup and view all the answers

    Why is it important to cool the flask slowly?

    <p>To reduce stresses in the denture</p> Signup and view all the answers

    What is the result of packing the material before the dough stage?

    <p>Rapid loss of pressure occurs</p> Signup and view all the answers

    What is the initiator used in the polymerization reaction of PMMA?

    <p>Benzoyl peroxide</p> Signup and view all the answers

    What is a technique used to reduce polymerization shrinkage?

    <p>Using composite inlays</p> Signup and view all the answers

    Why is using composite inlays beneficial for patients requiring multiple restorations?

    <p>It reduces chair side time</p> Signup and view all the answers

    What is the effect of a higher amount of polymer matrix on the thermal coefficient of expansion?

    <p>It increases the thermal coefficient of expansion</p> Signup and view all the answers

    Which type of composite is more prone to marginal percolation?

    <p>Microfilled composite</p> Signup and view all the answers

    What is a notable difference in surface finish between microfilled and macrofilled composites?

    <p>Microfilled composites can take and retain a smooth surface finish</p> Signup and view all the answers

    How do microfilled composites compare to conventional composites in terms of compressive strength?

    <p>Microfilled composites have a lower compressive strength</p> Signup and view all the answers

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