Why are caps put on teeth? Dentists install crowns to perform several important functions. They protect weak teeth, restore broken teeth, prevent cracked teeth from breaking further, and support teeth that have large fillings. ... Crowns restore the appearance, shape, and alignment of a damaged tooth Is zirconia stronger than metal? Zirconia is derived from a metal. However, it has been used in the production of ceramics for quite some time. ... Impeccable strength: Zirconia is even stronger than porcelain. In fact, when compared to their porcelain counterparts, zirconia crowns offer 200 percent higher bending strength and flexibility