Metal-free crowns are a type of highly aesthetic restorations entirely made of ceramic. They can imitate natural characteristics of teeth, transmitting light like natural teeth. They fit in alignment much better, particularly if only some teeth are restored, rather than all of them. In such cases it is impossible to make a difference between Metal-free crowns and natural teeth. Their interior is made of materials described as biocompatible, which means that they do not cause any reaction of the surrounding tissue, enabling the gingiva to shape around them as if they were natural teeth. Metal-free crowns are a combination of supreme quality and durability.
Although mechanical properties of Metal-free crowns are similar to those of metal ceramic crowns, their advantages are far more numerous.
The interior of metal ceramic crowns is made of a metal alloy to which dental ceramic is fused in order to achieve an aesthetic effect.
The removal of dental substance (filing down of teeth) is far less extensive in the case of Metal-free crowns. For example, in order to make a metal ceramic crown it is necessary to remove 1.5 – 2.0 mm of dental substance, whereas in the case of Metal-free crowns, only 0.3 – 1.0 mm of dental substance needs to be removed.
In most cases, Metal-free crowns are made of zirconium or lithium-disilicate ceramic. In such a way the produced crown is made of a material similar to glass; it is light and transparent, and at the same time as resistant as natural teeth.
Crowns made of zirconium are a very popular type of non-metal restorations. Zirconium has exquisite mechanical properties. This white material is one of the most solid ones. Initially used in space technology, after long-term research, it was also applied in some branches of medicine, e.g. in orthopaedics for the production of artificial hips. Crowns made of zirconium have extraordinary aesthetic and mechanical properties, owing their expansion to the possibility of producing wide span Metal-free bridges. Although this turned out to be a revolutionary material in crown production technology, aesthetic properties of lithium-disilicate ceramic are still unmatched.