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Restorative & Materials · single question

All of the following contribute to an opaque-appearing crown EXCEPT one. Which is the EXCEPTION?

  1. Using a different shade of opaque
  2. Inadequate translucency of the porcelain
  3. Insufficient tooth preparation depth
  4. Thick metal substructure
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Correct answer: A. Using a different shade of opaque

  • A. CORRECT. Simply using a different shade of opaque does not necessarily make the crown appear opaque to the observer — shade selection affects color, not the level of translucency/opacity. The question asks what causes the crown to look opaque, not about opaque internal layers.
  • B. Low-translucency porcelain will appear more opaque because it reflects rather than transmits light.
  • C. Insufficient preparation leaves insufficient room for adequate porcelain thickness, forcing the technician to use more opaque to block the metal, resulting in a flat, opaque appearance.
  • D. A thick metal substructure blocks light transmission and makes the final restoration look opaque.

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