Dental crowns can be made metal or nonmetal. Metals used in the preparation of metal-ceramic dental crowns are chromium, molybdenum and palladium (nickel is abandoned due to allergic reactions). The name metal crowns is somewhat deceiving, because they only have a metal core, while the outer part is ceramic.
Non-metal crowns are made of zirconium, i.e. from zirconium dioxide (ZrO2), that belongs to the group of ceramic materials of high resistance. It is a zirconium oxide that is, besides making artificial teeth, used for artificial diamonds and other purposes that require high durability and is not to be confused with the mineral zircon, which is used for costume jewelry, nor with the metal zinc. In addition to the metal-ceramic dental crowns and zirconia ceramic covers it it possible to make dental crowns from alloy of gold and titanium, which is an option that is already almost completely withdrawn from practice because of high prices.
We recommend nonmetal zirconia dental crowns to all patients who can afford them, because they possess impeccable biocompatibility, physical properties and aesthetics. Combination of nonmetal zirconia dental crowns in the anterior region of the jaw and metal-ceramic porcelain dental crowns in the posterior region of the jaw is often, and the noticed trend is that more and more people are choosing zirconia dental crowns instead of metal ones.
The key difference is that the metal, as the base of metal-ceramic crowns, is shaped by hand, while zirconia crowns are machine made with the help of computer based 3D scanner, which leads to a much more precise fit of zirconia crown on the tooth. The metal-ceramic porcelain covers contain metal as a base, upon that metal it is later applied dental ceramic in the laboratory and the form of the teeth is obtained. Metal itself, as a base of dental crown, represents a problem in obtaining excellent aesthetic results due to its gray color. On the other hand, zirconium can be coated in any desired color, so that, if the selected color of the future ceramic porcelain covers is A1, then the zirconium as the base of the crown is colored in A1, unlike metal, which is always gray. Zirconia cover can be sanded and plan just to the gums, and there will not appear sthetic problem where you can “see metal”.
As for the difference in firmness between zirconia and metal, it should be duly noted that the zirconium is much harder material. However, it can sometimes be a disadvantage. In cases where it is necessary to create a ceramic dental bridge of greater range, such as the bridge between the threes and eights, metal-ceramic structure is better than zirconia non-metal structure due to the higher elasticity of the material.
Patients claim that, in the places where they have a metal-ceramic crowns, it is harder and longer to get used to the new dental covers, that the feeling is different and that the color is a little heterogeneous, while on the new non-metal crowns are accustomed to in one or two days. This can
be attributed to the characteristics of zirconia, which is biocompatible, unlike metal. Metal in metal-ceramic dental crowns can produce the appearance of galvanic currents in the mouth and greater irritation of the soft tissue, ie. gum, and sometimes allergic reactions to soft tissue. Production of metal dental crowns and their planning under the gums in time leads to gum recession and bone loss, the reactions of soft tissue as well, ie. the gums to a foreign object. However, the process of gum recession occurs naturally, so it can not be said that metal crowns are direct culprit.