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Dental Materials Science Flashcards

7 cards from real DMD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which time-dependent deformation property of dental amalgam refers to its slow permanent distortion under sustained compressive stress?

    Answer: Creep

    Creep is the time-dependent permanent deformation of amalgam under sustained load, contributing to marginal deterioration over time.

  2. Which impression material sets through an irreversible chemical reaction and cannot be reconverted to its original state for reuse?

    Answer: Alginate

    Alginate is an irreversible hydrocolloid — once it gels through an irreversible chemical reaction, it cannot be returned to its sol state.

  3. The primary setting reaction of zinc phosphate cement involves which chemical process?

    Answer: Acid-base neutralization

    Zinc phosphate cement sets by an acid-base neutralization reaction between zinc oxide powder and phosphoric acid liquid, forming zinc phosphate crystals.

  4. The silane coupling agent incorporated in composite resins primarily functions to:

    Answer: Bond inorganic filler particles to the organic resin matrix

    Silane acts as a bifunctional molecule, bonding the inorganic filler particles to the organic resin matrix and improving the mechanical properties of the composite.

  5. Which property of a dental material specifically describes its resistance to permanent surface indentation?

    Answer: Hardness

    Hardness is defined as resistance to permanent deformation or indentation of the surface, commonly tested by Vickers, Knoop, or Brinell methods.

  6. Which dental ceramic exhibits the highest fracture toughness among ceramic restorative materials due to a transformation toughening mechanism?

    Answer: Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP)

    Y-TZP zirconia has the highest fracture toughness because stress at a crack tip triggers a tetragonal-to-monoclinic phase transformation that impedes crack propagation.

  7. During light-cured composite polymerization, the material shrinks primarily in which direction?

    Answer: Toward the light source

    Composite resins shrink toward the light source (the bonded surface) during polymerization as the resin chains contract toward the initiation point.