Root canal treatment is the most effective and thorough method for treating endodontic and periapical diseases, and it is also the most popular advanced treatment technique internationally. It is a complex operation, with numerous and fine instruments and long treatment time, generally including the following four steps: 1, root canal preparation DD open the pulp, thoroughly remove the diseased and necrotic pulp tissue, measure the length of the root canal and make root canal expansion; 2, root canal flushing DD is a repeated operation in root canal treatment, rinsing the root canal with tiny fragments of organic matter and tiny fragments of hard tissue cut off and other sources of infection; 3, root canal Disinfection DD drug disinfection is most commonly used, it is placed in the root canal with a small amount of cotton twist, and the hole is sealed with temporary sealing material; 4, root canal filling DD is the last step of root canal treatment, and it is also the most important step in root canal treatment. At present, it is common in clinical practice to fill the root canal with root canal filling agent plus the tip of dental cement, so that the root canal system can be tightly closed. The above four steps are usually performed in 3 times to achieve thorough disinfection and sterilization and to ensure the efficacy of the treatment, with an interval of about 1 week each time. During the treatment process, several dental films are taken, which can help the doctor understand the root canal shape, length, and periapical tissue destruction, and provide a reference basis for proper diagnosis and treatment. It is also possible to understand the effect of root canal filling and the comparison of observations before and after treatment of certain dental diseases. This is often incomprehensible to the patient, but necessary to achieve satisfactory treatment results. Root canal therapy is an advanced filling procedure that is time consuming and slightly more expensive, but is beneficial in ensuring the long-term treatment of the affected tooth.