Which ceramic crown material is weakest?

Which ceramic crown material is weakest?

• A. Monolithic zirconia
• B. Lithium disilicate
• C. Metal-ceramic
• D. Feldspathic porcelain

Answer: (D)

Understanding how strength and brittleness of ceramics affect performance under biting forces is key here. Feldspathic porcelain has the lowest flexural strength and is the most brittle among common crown ceramics. That makes it prone to microcrack formation and crack propagation under occlusal loading, so chipping or fracture of the veneer is more likely. The other options resist cracking better: monolithic zirconia has a very strong crystalline structure that gives high fracture resistance; lithium disilicate features an interlocking crystal network that improves crack resistance while still offering good esthetics; metal-ceramic crowns gain much of their strength from the metal substructure, with the ceramic veneer mainly contributing esthetics and being less capable of bearing the full load alone. So feldspathic porcelain is the weakest choice because its composition and microstructure translate to the lowest resistance to fracture among these materials.

Understanding how strength and brittleness of ceramics affect performance under biting forces is key here. Feldspathic porcelain has the lowest flexural strength and is the most brittle among common crown ceramics. That makes it prone to microcrack formation and crack propagation under occlusal loading, so chipping or fracture of the veneer is more likely. The other options resist cracking better: monolithic zirconia has a very strong crystalline structure that gives high fracture resistance; lithium disilicate features an interlocking crystal network that improves crack resistance while still offering good esthetics; metal-ceramic crowns gain much of their strength from the metal substructure, with the ceramic veneer mainly contributing esthetics and being less capable of bearing the full load alone. So feldspathic porcelain is the weakest choice because its composition and microstructure translate to the lowest resistance to fracture among these materials.