The flexural strength of a material used in prosthetics is a measure of how much the material can flex under chewing forces without fracturing or permanently bending. Traditional metal alloys have very high flexural strength and do not flex in long bridge structures. First-generation zirconium blocks had a flexural strength of approximately 1200 MPa and were very successful in long posterior bridges, but their translucency was poor. Today, ultra-transparent (cubic phase) zirconium, produced to improve aesthetics, has a flexural strength of approximately 600-700 MPa. This directly affects bridge designs. If a long bridge with 3 or 4 units is to be made in the posterior region, choosing highly aesthetic but weak cubic zirconium will cause the bridge to fracture during the first hard chewing; therefore, in long bridges, standard zirconium substructures with high flexural strength must be chosen rather than prioritizing aesthetics.
