There are two types of materials used in cast metal crowns, one is precious metal alloy and the other is non-precious metal alloy. The most commonly used precious metal alloy is gold-palladium alloy, whose main components are gold and palladium. The main advantages are good casting performance, good biocompatibility, low irritation to gum tissue, low hardness, and good bite comfort. The disadvantage is that it is more expensive. Non-precious metal alloys are commonly used nickel-chromium alloys, whose main components are nickel and chromium. The main advantage is that the price is relatively cheap. However, the biocompatibility is slightly worse than that of gold-palladium alloy, the hardness is high, and the comfort when chewing is not as good as the former. In addition to these two types, there are also silver-palladium alloys. These alloys have been proven to be very safe. As long as they are produced by regular companies and have relevant certificates, you can absolutely rest assured.