Non-precious metal porcelain teeth Nickel-chromium alloy porcelain crowns: Nickel and chromium are the main components. The inner crown is made of base metal nickel-chromium alloy casting, in the complex oral environment, the metal part exposed in the mouth will slowly decompose and release black oxide, resulting in local tissue staining, which is the most important reason why this kind of restoration will lead to black line of gums. Yu Zhe, Department of Stomatology, Xuanwu Hospital, Capital Medical University Semi-precious metal porcelain teeth Titanium porcelain crown: belongs to the better biological material in the ordinary metal porcelain crown. “Titanium” metal content of only 4% to 5%, the majority of other components are still nickel-chromium, and nickel-chromium alloy porcelain crowns are not essentially different. Gold-plated inner crown porcelain crown: on the basis of the nickel-chromium porcelain, and the tooth and gum contact parts gold-plated, the outer layer of porcelain. Cobalt-chromium inner crown porcelain crown: where the cobalt will not exceed 30%, still need to add nickel to improve its plasticity, in fact, belongs to the nickel-chromium alloy, but also better than titanium porcelain crown. Alloy porcelain crowns: silver content of more than 50% of the inner crown porcelain teeth containing silver, nearly the price of gold inner crown porcelain crowns. Pure titanium crown porcelain: because titanium has excellent biosafety, light weight, stable chemical properties, mechanical strength and other characteristics, is the ideal metal in oral restorative materials, but because of its high melting point, easy to oxidation, there is pure titanium thermal expansion coefficient is lower than the porcelain powder coefficient is too large, is the ideal coefficient ratio of about 7 times, that is, the chances of pure titanium porcelain porcelain chipped porcelain to higher than other types of porcelain. Precious metal porcelain teeth Gold alloy inner crown porcelain crown: its inner crown contains more than 84% gold. Platinum porcelain crowns: mainly platinum-based metal crowns, but because the domestic oral use of white gold rely on German imports, now out of stock, almost disappeared in the clinic. Gold deposition porcelain crowns: the use of deposition technology, the production of porcelain crowns, reducing the process of turning a mold, so that the production error is smaller, but due to the low density of gold soup, the chances of chipped porcelain is too high. All-porcelain teeth All-porcelain is what we call all-porcelain teeth without metal crowns, the inner and outer layers are all porcelain composition, is the darling of dental aesthetics, can fully reflect the color and shape of natural teeth, the effect is very good. Cast porcelain crowns: the inner crown is made of porcelain, and then outside of it is made of more transparent veneer porcelain, which can ensure the strength of the porcelain crown, but also make the aesthetic effect closer to natural teeth. Strength up to 350mpa. one generation of white garnet for the inner crown, also called cast glass ceramic; second generation of lithium-based ceramic for the inner crown. Alumina-based all-porcelain crowns: more strength, up to 400mpa. Although the translucency has decreased but still can obtain good aesthetics, the price is higher than cast porcelain crowns. Zirconia-based all-porcelain crown: is the best strength is also the most ideal porcelain restorations, especially suitable for anterior teeth cosmetic restoration, its strength has exceeded the metal porcelain crown, up to 900mpa.