A Crown can be made from different materials but all serve the same functions. Crowns can be all porcelain, gold, metal, or porcelain fused to metal. Teeth in the front usually utilize a crown that is porcelain fused to metal. The metal acts as a substructure giving the crown more resistance to fracture, with an outer layer of porcelain. You have the strength of the metal, but then you also have the aesthetics of porcelain.
All Porcelain Crowns
Next you have all porcelain crowns which are the most aesthetic of the crowns. They’re just as strong as any other crown, and highly fracture resistant. You can change the shape or color of a tooth as well as strengthen the tooth. If there are multiple fillings in a tooth, or the tooth has had a root canal, then the tooth is more fragile and more prone to fracture. A crown is placed over the tooth to support it and decrease the likelihood of it fracturing.