For a long time metal was used in order to provide the endurance for porcelain restoration.The restoration which is made by covering metal with porcelain did not have anough aesthetic under the light such as camera flash,neon. 
Nowadays restorations are made by a material called zirconium which has no metal.Zirconium was also used for orthopedic prothesis and for spaceships. 
Zirconium which is used for crown and bridge as substructure is either very strong or aesthetically looked more natural. 


As a substructure white coloured zirconium alloy is used fort his system.The biggest advantage is because of being very strong it provides full aesthetic to the backside bridges.The system has 900Mpa resistance. 

Even many things effect the appearance of the crowns,the most important thing is that they are transperant.Because of being tranperant depth and vigour are mentioned so,zirconium is the nearest to the natural teeth. 



1-Metal supported crowns are seen as if there is no tooth in the mouth because of not to be transperant.Zirconium is transperant and all kinds of lights pass.The most aesthetic material in dentistry. 
2-Zirconium not allergic,a friend of tissue. 
3-Because of being transperant zirconium is the nearest to the natural.Even the dentist do the best,metal supported teeth are seen matt and artificial so,zirconium is preferred mostly fort he frontal teeth. 
4-Zir conium does not have metal as substructure so,there is no dark line between crown and gum.more aesthetic. 
5-Metal supported crowns are sticked to the teeth mechanical but,zirconium is held mechanical and chemical so,holding is stronger. 
6-Zirconium is insulator so,there is no hot or cold sensetiveness. 
7-Metal supported crowns have the possibility of allergy but,zirconium has no. 
8-If there is a recession,zirconium keeps its aesthetic appearance.Gum harmony is the best.For zirconium it is not mentioned about being purple in the gum as a result of gum disease or recession.

R1-Cross-section of a completed crown 
    b-matt porcelain 

R2-By the beginnig of 2002,all over the world dentists started to this zirconium system.By that new application there is no anxiety of aesthetic.