Tooth Colored Crowns (Caps)
Porcelain applied over a dark metal casting for many decades has been the only choice for crowns that appear tooth colored (cosmetic). There were (and are) problems with this type of crown. First, perfect enamel color can be very difficult to achieve due to the dark metal under the porcelain and at times a grey edge at the gum margin. Although there are alternatives for less dark metal, the problems still exist to a certain extent. Second, porcelain is a glass - plain and simple - and glass can break. It is fairly common to see porcelain to metal crowns on molars (back teeth) chip or break completely free of the metal substructure. For many years there has been increasing patient demands for improved esthetics in dental restorations. This demand has been especially strong in the area of front teeth that require crowns (caps). There have been MANY attempts over the past few decades or more to provide "all ceramic/porcelain" crowns. In other words, a crown that would not have a metal substructure under it. The reasons for wanting to eliminate the metal are primarily to get rid of the dark line at the very edge of the crown and to let more light pass through (to look more lifelike). Generally speaking, all these materials have failed to live up to expectations. Fracturing was the primary problem. Time passes and materials and techniques improve. There now exists NEW all ceramic (not a porcelain) materials that have revolutionized the creation of enamel colored crowns.
2 of these NEW materials are -
Exhibiting superior durability (multiple times stronger than tradiitional porcelain) and the most color robust ceramic system to date. The opalescence, translucency and light diffusion properties of lithium disilicate were all designed to replicate natural tooth structure for beauty and undetectable restorations. Although both front teeth and back molars can be made, these are best suited for the front teeth where chewing pressures are the least.
Virtually unbreakable and biocompatible. Over 10 times more strength than traditional porcelain, resistant to chipping, cracking or breaking in the mouth makes zirconia crowns ideal for bruxers and grinders, who have broken their natural teeth or porcelain restorations in the past. Zirconia crowns are a combination of zirconium (a tooth colored metal) and its oxide (a white powder ceramic). Dentists have long relied on full-cast gold for long-term durability and strength. But with the introduction of all zirconia restorations an equally strong tooth colored solution is now available. What's more, when compared side-by-side to full-cast gold and porcelain metal crowns, zirconia crowns are the most natural-looking choice. Zirconia works very well on the back molars where strength is required.
But there have been improvements in metal based porcelain crowns as well.
- Using gold metals instead of darker metals for a "warmth" of color.
- Better (much better) porcelains for better colors.
- Better preparing of teeth so that there is sufficient porcelain for natural light to come through.
- No metal exposed at any areas that can be seen ...what is referred to as "porcelain margins".