Which shows the correct order of increasing flexural strength of dental ceramics?

The correct order of increasing flexural strength of dental ceramics is shown in option B, which includes feldspar, leucite, lithium disilicate, alumina, and finally zirconia. This sequence aligns with the properties of these materials as used in dental applications.

Feldspar ceramics have the lowest flexural strength because they are primarily composed of glass, which is not particularly strong under flexural forces. Leucite-reinforced ceramics, while stronger than feldspar, still do not reach the strength level of lithium disilicate. Lithium disilicate is known for its superior mechanical properties and has been significantly enhanced in strength through its crystalline structure, making it a popular choice for dental restorations.

Alumina ceramics present a notable increase in strength compared to lithium disilicate due to their higher density and structural integrity. Finally, zirconia is recognized for having the highest flexural strength among these materials, making it ideal for applications requiring robust durability and resistance to fracture. The differences in these materials' compositions and structures account for the gradation in their flexural strengths.

This understanding helps practitioners select appropriate materials based on the mechanical demands of specific dental applications.