Which of the following is NOT true regarding low-fusing porcelains?

Feldspathic veneering porcelain is known for its aesthetic qualities, providing a natural appearance to dental restorations. However, it does not exhibit the same level of flexural strength as some other types of dental ceramics. Low-fusing porcelains are designed for applications where lower firing temperatures are beneficial, often leading them to possess varying physical properties compared to those of high-strength materials.

In the context of the other options, it is accurate that low-fusing porcelains can indeed have different opacities for metal-ceramic restorations, allowing dentists to choose them based on the specific aesthetic requirements of the case. Additionally, the content of leucite in low-fusing porcelains tends to be minimal, which differentiates them from some high-strength ceramics that use leucite to enhance strength and durability. The grain size of the porcelain can significantly influence wear resistance, as finer grains can lead to smoother surfaces, edge retention, and overall better performance in wear scenarios.

Thus, Option D stands out as the incorrect statement, as feldspathic veneering porcelain does not exhibit high flexural strength when compared to other materials that are specifically engineered for greater strength under load.