Root canals are treated with a crown sleeve, which prevents the tooth from fracturing. 1. Root canal treatment involves removing the infected nerve from the tooth, filling in the root canal with a substitute material, and then repairing the tooth to make it complete. 2. A root canal treated tooth is usually accompanied by a dental defect because the nerve is the nutrient supply to the tooth. When there is no blood circulation to the tooth, there is no nutrient supply to the dentin, and the dentin will become brittle and lack of support. Therefore, after root canal treatment, a crown must be made to prevent the tooth from fracturing. 3. Crowns are full crown restorations of equal size that are made by taking a model of the tooth after it is ground down and glued to the surface of the tooth, with the point of stress being the crown, which transmits the force to the root of the tooth, thus protecting the tooth for a longer period of time. Patients with tooth pain discomfort, should go to the hospital as soon as possible, the hospital to improve the relevant examination, under the guidance of the doctor for professional treatment, to avoid adverse consequences.