natural color dynamics with color "from the inside" as found in natural elements, instead of color "on the outside", with monolithic zirconia. As a result, the natural tooth, in terms of esthetics and hardness, is approached closer than crowns made from solid monolithic zirconia. This implies that the histo-anatomic dentin core is the key to esthetic crowns. Zirconia is the hardest known ceramic in industry and the strongest material used in dentistry, it has to be fabricated using a CAD/CAM process but not the conventional manual dental technology. Because of this monolithic zirconia does not wear itself as the normal vertical wear of 25-75 microns of natural enamel and porcelain, there are no clinical data on the fact whether as a consequence too high zirconia crowns will damage opposing dentition on the longer term. Although in two body wear testing of monolithic, veneered and glazed zirconia and their corresponding enamel antagonists showed similar wear, at least twice as much extensive, and branched enamel microcracks were observed in the samples opposing monolithic zirconia. Monolithic zirconia Monolithic zirconia crowns tend to be opaque in appearance with a high value and they lack translucency and fluorescence. For the sake of appearance, many dentists will not use monolithic crowns on anterior (front) teeth. Monolithic zirconia crowns are produced from a color- and structure-graded zirconia block and coated with a thin layer of glaze stains which also provides some kind of fluorescence. The "graded" zirconia crown has a darker cervical area consisting of tetragonal zirconia, a main tooth color in the buccal area, and a translucent incisal edge consisting of cubic zirconia. The only thing a dental technician has to do is to use the proper height of the zirconia block so that the crown fits in all the different color zones. Although on the outside the color gradient mimics natural teeth, they are still far from the optical, physical, biomimetic and esthetic properties of natural teeth. To a large extent, materials selection in dentistry determine the strength and appearance of a crown. Some monolithic zirconia materials produce the strongest crowns in dentistry (the registered strength for some zirconia crown materials is near 1200 MPa), but these crowns are not usually considered to be natural enough for use in the front of the mouth. Although not as strong, some of the newer zirconia materials are better in appearance but generally still not as good as