A few years ago, I read an article on the Internet about “causes of fatigue”, saying: “If you have a lot of teeth with metal fillings, there may be some mercury seeping into your body, and your body may accumulate a lot of toxic metals to weaken your strength.” . Recently there are “nickel-chromium alloy porcelain teeth cause kidney disease” network article. In fact, dental instruments, materials are biological materials, to enter the clinic must go through three major hurdles, one is the primary screening test to confirm that the material is not cytotoxic and genotoxic; second is the secondary test, the material and its infusion by oral or intravenous injection in animals to confirm that it is not systemic toxicity, no irritation, no allergies, etc.; third is the pre-clinical application test, that is, the material is made into a finished product for the corresponding animal The third is the pre-clinical application test, that is, the finished product of the material is used for the corresponding part of the animal, such as dental materials should not produce irritation of the dental pulp, oral mucosa, etc.; the testing of the material is carried out in the national designated institutions, according to the international standardization organizations (ISO Dental Technical Committee, FDI International Dental Federation, etc.) certification before entering the clinical application. The materials used in dentistry are in three main categories: metals, ceramics and polymers, and composite materials made of the three. Metal alloys are one of the most commonly used materials for dental veneers and are divided into precious metals (such as gold alloys), semi-precious metals (such as silver alloys) and base metals (such as nickel-chromium alloys), as well as silver amalgam for dental fillings. Gold alloy in the 18th century has been used in dentistry, is still the most ideal dental restorative materials. Its advantages are stable performance, not easy to oxidation; hardness is closer to natural teeth, not easy to wear the jaw teeth, but the price is relatively high. Currently in developed countries and regions are more widely used, with the improvement of living standards of our people, accepting precious metal denture (such as “gold porcelain teeth”) has been more and more patients. Experts jokingly say, please put gold and silver jewelry in your own mouth for dental inlays, both for health and to ensure the security of theft! Silver amalgam was first used in the mid-19th century, and ISO has clear rules about the amount of mercury in it, which will not be approved if it exceeds the standard. Although mercury can contaminate the environment before it solidifies, there is no evidence of health hazards associated with the use of amalgam fillings in humans. Therefore, silver amalgam remains one of the most important filling materials for posterior teeth today. Nickel-chromium amalgam is a dental alloy used in the 20th century, which is widely used for fixed denture restorations because of its high strength, good bonding with ceramics, and low cost. However, nickel-chromium alloy is not as stable as gold alloy, easy to oxidize, nickel ions in the saliva leaching, clinical individual patients may produce gingival staining, stomatitis and other allergic reactions, but there is no direct evidence that wearing nickel-chromium alloy restorations will produce lesions in other parts of the body organs. That is to say, whether kidney disease is indeed nickel-chromium alloy porcelain crowns caused by remains to be proven. Known as the 21st century metal material “titanium” in recent years more and more attention. Because of its excellent biological properties, pure titanium has been used as an intra-osseous value for dental implants. Titanium alloy due to high strength, good toughness, light specific gravity (only half of stainless steel, one third of the gold alloy), in the oral cavity is not easy to oxidation and crustal reserves and other advantages have been used to make movable dentures (“titanium bracket denture”) and fixed dentures (“titanium metal teeth “, “titanium porcelain teeth”), etc. However, due to the difficulty of processing and high investment in equipment, the price is on par with that of precious metal dentures. It should be emphasized that this does not refer to nickel-titanium alloy. At present, most of China’s dental materials rely on imports, mainly from Germany, Japan, the United States; only a few auxiliary materials produced by domestic manufacturers or Sino-foreign joint venture manufacturers. And whether it is used for clinical dental comprehensive chair or the production of denture mechanic equipment are also mostly dependent on imports. Therefore, the cost is high, but due to the low level of domestic consumption, the fee has been quite cheap. Therefore many people from outside the country are happy to return to their home country for dental veneers. The development of dental materials affects the development of the entire dental field, and we are looking forward to the introduction of more ideal dental materials that are more in line with the physiological structure and function of the human body.