Compare zirconia crowns to porcelain-fused-to-metal crowns in terms of strength and translucency.

• A. Zirconia provides high strength and fracture resistance with variable translucency; layered PFM can be more esthetically translucent but has metal substructure.
• B. Zirconia is weaker than PFM with lower translucency.
• C. PFM is stronger and less translucent than zirconia.
• D. Both materials have identical strength and translucency.

Answer: (C)

When comparing these crowns, strength and translucency are balanced by the materials’ structures. Porcelain-fused-to-metal crowns gain substantial fracture strength from the metal substructure, which makes them very durable under chewing forces. However, that same metal underneath the porcelain blocks and dulls light, so they are less translucent. Zirconia crowns, as a ceramic option, provide high strength from the tough zirconia lattice and can be made to look more translucent than metal-ceramic crowns. So, in general terms, porcelain-fused-to-metal crowns are stronger but less translucent than zirconia crowns.