Porcelain or all-ceramic crowns are recommended for restoration of teeth after root canal treatment. When the pulp is removed during root canal treatment, the tooth is not nourished by the nerves and blood flow, and the tooth becomes more and more brittle and cannot withstand the excessive biting stress, which may cause the crown or even the crown-root combination to fracture if it bites into a hard substance. If there is a root fracture, the tooth will not be able to retain the need for extraction, so after root canal treatment of the teeth, in order to extend the service life of the teeth, it is recommended that the crown of the tooth with porcelain crowns or all-porcelain teeth for protection. Porcelain crowns and all-ceramic crowns, the method is required to grind the tooth uniformly small circle, make a model, and then by the processing plant to produce a crown, and finally by the doctor cemented in the patient’s mouth to restore the shape of the tooth, set a porcelain crowns will protect the tooth, so as to prevent the tooth from being subjected to excessive occlusal pressure, the fracture of the tooth.