Dental defects are common and prevalent in dentistry, accounting for approximately 24% to 35% of the natural population. It is manifested by different degrees of damage or abnormalities in the texture and physiological anatomical shape of the hard tissues of the dentition. It is often caused by caries, trauma, wear and tear, wedge-shaped defects, developmental malformations, etc. It can cause adverse effects on the dentition, pulp, periodontal, mastication, aesthetics and pronunciation. Clinically, it is treated by filling and restoration methods. The more serious dental defects are often treated by restorative treatment. The most common restorative treatment method is crown restoration or pile crown restoration. Crown restorations are divided into partial crowns and full crowns, with full crowns being the most common. When the damage is too severe to achieve a good restoration with a full crown, a pile crown is required. The following is an introduction to full crowns and pile crowns. Full crowns Full crowns are restorations that cover the entire surface of the crown and are often made of metal, gold-porcelain or all-porcelain materials. Metal full crowns are commonly made of nickel-chromium alloy, pure titanium, etc. Because of the poor aesthetic effect, they are generally used only for posterior teeth. Among metal crowns, pure titanium full crowns have excellent performance and are biocompatible and do not irritate the gums and cause allergies. Also, due to the good physical properties of pure titanium, it has little effect on x-ray, MRI and other imaging examinations. Gold – porcelain crowns, that is, porcelain fused to metal full crowns, for the metal crown surface at high temperatures fused to tooth-colored porcelain layer of the restoration, often called porcelain crowns. At present, the more common are nickel-chromium alloy, cobalt-chromium alloy, pure titanium and gold alloy porcelain crowns. Nickel-chromium porcelain crowns contain nickel, which is a major allergen for some patients with metal allergies, and the alloy composition has the disadvantage of causing black lines on the gums at the edge of the porcelain crown. Cobalt-chromium porcelain crowns contain essentially no nickel and are less likely to cause allergies and gum lines. Pure titanium porcelain crowns inherit the fine tradition of pure titanium, and have good biocompatibility. Gold alloy porcelain crowns is the best aesthetic degree of porcelain crowns, mainly from the gold alloy similar to the yellowish color of dentin, in addition to the excellent metal properties of gold alloy make gold – porcelain bonding more solid and high precision, and rare allergy to gold alloy. Therefore, gold alloy porcelain crowns are an enduring type of porcelain restoration. All-porcelain crowns are the new favorite for full-crown cosmetic restorations, because they do not contain alloy base crowns, good crown transparency, better imitation of natural teeth, higher aesthetics, and basically no irritation and allergy to the gums. Zirconia all-porcelain and alumina all-porcelain are often used, of which zirconia all-porcelain has high strength and is suitable for full crown restorations of anterior and posterior teeth. In addition, there is CAD/CAM all-ceramic crown, that is, computer-aided design and production of all-ceramic crown, the biggest advantage of such all-ceramic crown is the design and processing of all-ceramic crown computer-aided, rapid production and high precision, conventional crown restoration generally requires a week or so of processing cycle, and CAD/CAM all-ceramic crown as soon as possible only two or three hours to complete, can save a lot of time. Second, the pile crown for the use of crown nails inserted into the root canal of the residual retention of the full crown restoration body. The full-crown portion of the pile core is the same as the type mentioned above. The difference is that because of the severe damage to the dentition, we need to place root canal piles inside the root and form the nucleus of the fixed crown, i.e., the pile core, in order to increase the strength of the dentition and improve the retention of the full crown. There are also a variety of materials for the piles, ranging from cast piles such as nichrome piles, pure titanium piles, and finished piles in different metals. It is worth mentioning the fiber piles which are becoming more and more widely used. Fiber piles are finished piles, and like other metal finished piles, they do not need to be processed in the mechanic’s room, saving a repeat visit. Compared to metal piles, fiber piles have good toughness and can effectively protect the remaining dentition, reducing the possibility of fracture by external forces after restoration. In addition, since fiber piles are mostly light in color, such as white, they can be used with all-ceramic crowns to achieve a good aesthetic effect.