There are often patients who have most of their teeth missing due to decay or trauma, etc. At this time, if they are treated with conventional filling methods, it will happen that the filling often falls off and so on. Moreover, if this kind of tooth with large defect is not treated and repaired in time, the tooth itself will be easily broken, and once the tooth after fracture cannot be retained, other remaining teeth will have to be grinded when repairing. For teeth with severe defects like this, as long as they have sufficient root length and adequate alveolar bone support, they can be restored using the original roots with a pile crown system after perfect root canal treatment to re-establish the occlusal relationship and restore function. The modern concept is not to extract the roots of the teeth that can be removed, because the impact of the presence or absence of the roots on the future veneer is huge and there is a fundamental difference. The perfect root filling treatment with pile crown restoration makes the phenomenon of mass extraction of tooth roots a history. I. What are crown and root remnants? Crown and root remnants are very common in clinical practice, and most of them were extracted in the past because there was no ideal treatment method. With the continuous improvement of people’s standard of living, more and more people are asking for preserving the restoration of crown and root remnants of anterior teeth. The development of modern restorative techniques and materials has enabled these needs to be met, not only relieving the patient’s pain, but also improving the aesthetics and function of the restoration. What is a pile crown A pile crown is a common restoration for restoration of residual roots and crowns. It is composed of two separate structures, the pile core and the outer crown. The retention of the pile core is obtained by inserting a pile into the root canal. The pile core-crown system consists of three components. The pile is the part inserted into the root canal, which is used to obtain good retention in connection with the core. The core is the part of the tooth that restores the clinical crown defect and is connected to the pile so that the pile and core form a single unit. The crown is the full crown, which is a full crown restoration that covers the entire core and is used to restore the tooth’s shape and perform physiological functions. Pile crowns are used for all restorations of dead pulp teeth. The advantage is the ability to restore the remaining tooth root without extraction. The main types of clinically used pile crowns are nickel-chromium metal pile crowns, precious metal pile crowns, carbon fiber and glass fiber pile crowns, and all-ceramic pile crowns. 1.Nickel-chromium metal pile core: It is a clinically used pile core with high strength and low price, but because its elastic modulus is significantly higher than that of dental tissue, it is easy to cause damage to dental tissue when excessive occlusal force is applied. 2, precious metal pile core: generally using high gold alloy, and the dental tissue fit well, have higher strength, toughness than the nickel-chromium metal pile core, can better protect the remaining dental tissue. But the cost is higher. 3.Carbon fiber and glass fiber pile: It is a preformed pile, made of carbon fiber wire or glass fiber wire bonded with resin, with higher strength and elastic modulus similar to dentin, which better protects the remaining dental tissues. It is easier to remove if needed (metal pile cores are generally not easy to remove) and is the first choice for restoring young permanent teeth with defects. Now there is the introduction of quartz fiber pile, its strength is higher than the glass fiber pile. 4, gold porcelain pile core: the main component of zirconia ceramic preformed pile, high strength, high biocompatibility, good aesthetics, suitable for all-porcelain crown or all-porcelain bridge restoration. And does not affect the nuclear magnetic examination, is a biological restoration material.