Modern dentistry has come a long way in developing restorative materials that have beauty, strength, and durability. When 50 % or more of a tooth has been lost, a crown is often the restoration of choice. Crowns or caps fully cover the entire visible portion of a tooth above the gumline to restore its shape, size, strength, and appearance. As a dentist who uses the best modern materials, Dr. Keith Tang commonly uses all ceramic or metal free crowns that fit almost seamlessly and look like a natural tooth.
Several decades ago there were only gold crowns or “porcelain fused to metal” (PFM) crowns. The problem with PFMs was that the dark oxidized metal has to be opaqued out and there was a black area at the gumline as the light reflected the metal. This was the standard type of crown in dentistry for years.
When high strength is desired, particularly in the back areas of the mouth, full contour zirconium crowns are now used. Zirconium is a metal free substitute that is extremely strong. Because this material is already white there is no gray at the gumline with these crowns. Zirconium has some translucency but reflects most of the light.
When the ultimate esthetics are needed in the smile zone, feldspathic porcelain, ceramic optimized polymer (Ceromer), or Emax (lithium disilicate) crowns are used. Feldspathic porcelain is a more translucent and esthetic material, but weaker because it is a glass ceramic. Ceromers and Emax are types of porcelain mixed with other things to make them stronger, but less translucent. Often crowns in the front areas use a combination of a stronger metal free coping and porcelain stacked on the outside of it for greater esthetics.