Zirconium Crowns Turkey Today, when a restoration needs to be made to the crown part of a tooth, it is necessary to use biocompatible materials in the mouth, which are suitable for the human body. From the past to the present, metal supports have been used along with plastics and then porcelain has been used on metal supports. In the last thirty years, the use of porcelain dental crowns on metal props have spread around the world.