Porcelain-fused-to-metal restorations were successfully developed in the United States on 1950. It is made of metal inner layer covered with porcelain powder similar to natural teeth and sintered in vacuum. Both the strength of metal and the beauty of porcelain. Strong bending resistance. High corrosion resistance and stable color. Metal-free porcelain teeth refer to porcelain teeth without metal inner crowns, which belong to all-ceramic teeth. Appeared in the late 1980s. It is mainly used to make a single porcelain crown or repair the front teeth to improve the appearance. Such as tetracycline teeth, dental fluorosis, dead pulp teeth and other discolored teeth. Then, among the imported restoration techniques, porcelain teeth were undoubtedly the best in tooth shape at that time. Beauty crown, a newly developed dental cosmetic technology, was introduced by some practitioners who were sensitive to external diagnosis in the early 1980s, not far from Wan Li. For adults, buck teeth, dislocated teeth, deformed teeth and pigment teeth can be corrected and repaired completely and quickly, without tooth extraction, and the whole process is painless. Good biocompatibility, no black line on the gums, white and neat teeth for 7 days, and commitment to beautiful teeth for life. The birth of porcelain teeth and the main problems to be solved are mainly in Europe and America. Naturally, Europeans and Americans pay more attention to treatment than modeling and aesthetics, so the research on porcelain teeth in Europe and America is mainly on materials and casting technology. For the teeth of Europeans and Americans, the enamel layer is much thicker than that of Asians, and there is no problem of tooth preparation, which directly leads to the neglect of tooth preparation in relevant research in Europe and America. When the same technology system was applied to Asia, the situation changed fundamentally. Keywords: enamel In addition to the above factors, the social situation of porcelain teeth in China has also aggravated the above problems, resulting in a worse social impact. Limited by the domestic economic level, dentists who pursue economic benefits can easily compromise with users' demands for extremely low prices, which is also the reason why base metal porcelain teeth abandoned abroad more than 20 years ago are widely used in China. A pair of pale dentures is not only very unsightly, but also constantly releases toxic metal elements, which is harmful to the mouth and seriously harms health. It can be seen that porcelain teeth, an exotic product, have been widely used in China, but its own technical system and domestic dentists' compromise on the domestic status quo, rather than sticking to the bottom line of medical ethics, make it hard to accept. Beauty crown and porcelain teeth can be said to be twin brothers in tooth beauty. They are closely related and both are messengers of beauty. The appearance of the beauty crown inherited the advantages of porcelain teeth, but also had some technical characteristics that porcelain teeth did not have, so the introduction of the beauty crown was logical at that time. Whether this is the case or not, let's take a look at the key words: the beautiful diamond teeth have to mention the beautiful crown. In the early 1980s, the Korean beauty industry began to flourish, and dental beauty began a new chapter. Dental practitioners in Korea have gradually discovered the essential differences between Europeans and Americans and Asians in their research. Porcelain teeth can no longer meet the needs of Asians for dental health and beauty, so they resolutely gave up the porcelain teeth technology that they had been using before, and instead developed tooth beauty technology that is more suitable for Asian dentin, so the beauty drill teeth came into being at that time. In the early days of Korea, because it was more suitable for the teeth of Asians, especially in the preparation of teeth, it was completely tailored to the teeth of Asians, and thinner, healthier, stronger and more beautiful materials were used. At that time, there was no difference, which set off a craze for beauty drills. In this upsurge, Kim Yong-soo, president of YOUNSOO Plastic Surgery Hospital in South Korea, became the only plastic surgeon in South Korea who was received and commended by the President for his beauty drilling technology. Some dental practitioners with advanced information in the coastal areas of Guangdong Province, China, saw the popularity of dental drills in South Korea, and waited for an opportunity to come to South Korea for thousands of miles to learn this emerging dental technology. We all know that a patented technology can be imported or even imitated, but without the support of original technology, it is really a thousand miles away. After studying in Korea for a period of time, these plastic surgeons in coastal areas returned to China to open their own dental clinics, transforming the skills they learned in Korea. This is the beauty crown we see now. What's more, the effect of copying this technology directly from these so-called returning practitioners is naturally unknown. Because these practitioners have learned different original cosmetic drilling techniques in Korea, the technical level of cosmetic teeth is also uneven, which is manifested in the following aspects: 1, hospital structure. In the mid-1980s, YOUNSOO Plastic Surgery acquired the largest dentistry in Korea at that time, which was regarded as the beginning of plastic dentistry. YOUNSOO's research on plastic surgery has reached the extreme, and he has also invested a lot in solving dental problems. YOUNSOO has also won the reputation of a pioneer in plastic dentistry because of his rigorous research attitude. 2. On the technical level, American drilling teeth came into being in the 1980s. Now, after more than 20 years of technical tempering, materials, health and beauty are self-evident. The return of the American crown from the so-called academic achievements to the present is also a change of more than 20 years. Due to the lack of original technology, it is gradually drifting away on the road of beautiful tooth restoration. 3. ergonomics. In the process of development, the tooth shape has not only been the problem of defending teeth from pseudo color, but also gradually extended to the overall remodeling of the three courts (eyebrows and hairline as the upper court, eyebrows to nose as the atrium, and people to chin as the lower court). Using sophisticated computer, the most suitable tooth shape is designed from the whole face, which highlights the uniqueness of beautiful diamond teeth. In the process of making beauty crowns, because there is no design of precision instruments, the plasticity in shaping the three courts is very small, and the teeth produced often lack personality.