All-ceramic crowns are widely used in cosmetic restoration of dental defects and partial dental defects because they have excellent light transmission and light reflection properties, can reproduce the translucent depth and color depth of natural teeth have good biocompatibility, and degrade continuously in the oral environment and other significant features. Performance characteristics of all-ceramic crowns and its restoration of indications and non-indications 1, performance characteristics: (1) has a mechanical strength similar to that of hard tissues, fatigue resistance, wear resistance, resistance to mastication, but the tensile strength, flexural strength and impact strength is low, not suitable for repairing temporomandibular joint disorders, occlusal overbite and overconsolidation and other cases. (2) Low thermal conductivity, non-conductive, lighter than metal porcelain material. (3)It has good chemical stability and does not produce deterioration and denaturation in the complex environment of the oral cavity for a long time. (4)Excellent biocompatibility, can reduce plaque aggregation, reduce gingival margin redness and shrinkage. (5)Easy to form, easy to modify, small shrinkage. (6)Good colorability, high surface gloss, excellent transparency and translucency, with aesthetic effect similar to natural teeth, without the problems of translucent blue, black line and discoloration of the gingival margin of metal porcelain teeth. (7) Insulation, live pulp protection, X-ray partial blocking. 2.Indications (1)The crown of the large part of the destruction of multiple defects is not suitable for filling treatment. (2) Anterior teeth incisal angle, incisal edge defects, general restorative materials are difficult to obtain good retention. (3) Partial fracture of the crown, loose folds have been extracted. (4) Teeth whose aesthetics are affected by abnormal development or color, such as tetracycline, fluorosis, pulpless discoloration and congenital malformation. (5) Individual teeth with insufficient height and need to elevate the occlusion. (6) Those who are allergic to metal or plastic. (7)Those who have misaligned or twisted teeth and are not suitable for orthodontic treatment. (8) Teeth that need to restore neighboring points, such as small gaps between front teeth. (9) High aesthetic requirements, and can ensure oral hygiene and attention to the protection of all-ceramic crowns. 3, non-indications (1) tooth pulp cavity is too large or pulp angle is too high (such as milk teeth, young permanent teeth), tooth preparation is easy to penetrate the pulp. (2) Clinical crown is too short, the tooth is too small to ensure that the restoration of the resistance and retention requirements. (3) Teeth with severe abrasion. (4) Affected teeth with opposite edges, deep overdentures, and tight occlusion. (5) Teeth with narrow necks that affect tooth preparation, or teeth with insufficient tissue resistance after tooth preparation. (6) Due to other diseases not suitable for fixed restorations, such as periodontal disease, night grinding teeth. There are many types of all-ceramic restorations, except for all-ceramic crowns, which also include porcelain piles, all-ceramic bridges, porcelain inlays, porcelain veneers and porcelain piles. All-ceramic crowns are the most widely used restorations, the indications are basically the same as metal porcelain crowns, the special features are allergic to metal cases and patients with high aesthetic requirements for the cervical margins of anterior full crowns. Porcelain core piles are aesthetically pleasing, high strength, and have little effect on the color of the crown, making them an excellent choice for patients with high aesthetic demands. In addition, porcelain core piles are biologically safe, X-ray transmissible, and fit well into the root canal wall. The main method of fabricating porcelain core piles is the hot die casting technique. Two types of all-ceramic crowns can now be fabricated in our clinic, alumina-permeable all-ceramic and zirconia all-ceramic crowns, the former for anterior teeth and the latter for posterior teeth due to their greater strength. The following is a clinical case illustration, a patient’s right side mesial incisor was discolored after root canal treatment and needed crown restoration, the patient’s age was 23 years old, the transparency of the opposite side of the homonymous tooth was good, the occlusal relationship was normal, it was suitable for all-ceramic crowns restoration, the patient chose the alumina infiltration all-ceramic, and the restoration result was good, the patient was very satisfied.