I’m often asked by patients why they need crowns after root canal therapy, and I’m going to briefly summarize it today in the hopes that it will help! Root canal treatment, commonly known as nerve pumping, is the dentist to have lesions in the tooth open, the tooth inside the inflammation, necrosis of the pulp tissue with a variety of instruments to remove clean, and the pulp cavity (including the pulp cavity wall) disinfection, clean, and then finally with the gum and other things to the pulp cavity tightly sealed up. Mei Xingcheng, Department of Stomatology, Jinan Hospital of Traditional Chinese Medicine Patients who have undergone root canal treatment often hear doctors suggesting crowns after root canal treatment, but do not understand why crowns are necessary. Root canal treatment is a treatment method for endodontics and periapical disease, and crown is a dental restoration method. Whether or not crown is needed after root canal treatment depends on the degree of destruction of the tooth, if the tooth is destroyed to the extent that it can not be filled with filling material or can not be filled with enough strength to restore chewing function, crown is needed, otherwise it can be filled with permanent filling material. Why need to do crown after root canal treatment, there are three main reasons: 1, because the need for root canal treatment of the tooth is generally caries (worm tooth), defective, although the root canal treatment is completed, but the remaining tooth tissue is very fragile, very easy to fracture, cracked, lost normal function, simply with the material has not been able to restore function. 2. Root canal treatment involves the use of medication and instruments to remove and sterilize as much debris and bacteria as possible from the root canal. However, if the sterilization process is carried out carefully, it is necessary to remove a lot of bacteria-infected teeth and dental tissues that have to be repaired. Therefore, most of the teeth that have undergone root canal treatment may not be strong enough to support the chewing force and may break down, and it is not possible to restore the function with materials alone, and even if it is possible to do so, the long-term effect will not be good. 3. After root canal treatment, the tooth loses its nutrient supply from the pulp, just like a tree that loses its roots, slowly withers and becomes fragile, causing the tooth to become more brittle and prone to splitting. Due to these three reasons, the supporting force of the whole tooth is obviously weakened, and may not be enough to support the chewing pressure under certain specific conditions and is prone to crown splitting, so it is necessary to make a crown in time to protect it.