Nickel-chromium porcelain teeth: Nickel-chromium alloy is corrosion-resistant and inexpensive, and is currently the most widely used porcelain teeth made in China. Medical nickel-cadmium alloy, mainly composed of nickel, chromium and a small amount of other metal elements harmless to the human body, the adverse effects of nickel-chromium alloy on the human body is mainly caused by the nickel in it. Its advantage is the lower cost, the disadvantage is that the edge of the fit is slightly poor, and gingival contact side easy to appear a green, gray line, slightly affecting the aesthetics, occasionally chipped porcelain phenomenon occurs. Cobalt-chromium porcelain teeth: cobalt-chromium porcelain teeth – an alternative to nickel-chromium porcelain teeth. It is mainly developed for the toxicity of nickel and beryllium, biocompatibility is better than nickel-chromium alloy, not easy to allergy, corrosion resistance. The problem of black lines on the gums is significantly improved compared to nickel-chromium porcelain teeth, but there are very few people who still have the problem of black lines on the gums. The naked eye cannot tell the difference. Titanium porcelain teeth: its main components are nickel, chromium and a small amount of titanium, titanium content is very low, the current titanium alloy used in hospitals and clinics only contains 4% to 6% of titanium, after a multi-processing content has been very low. Its little difference with the nickel-chromium alloy. So this metal can not play the excellent biocompatibility of titanium, but is just an excuse and means for clinics to increase their fees.