Root canal therapy is a therapeutic procedure for tooth, pulp, and apical lesions. Root canal therapy is a treatment that removes the necrotic material from the root canal, disinfects it appropriately, and fills the root canal to remove the undesirable irritation that the contents of the root canal can cause to the tissues surrounding the root tip, preventing the development of periapical lesions or promoting the healing of periapical lesions. The process of dental root canal treatment involves the use of dental root canal instruments to prevent periapical lesions from occurring or to promote healing of periapical lesions by thoroughly removing the infected pulp as well as the infected dentin and toxic decomposition products, and then tightly filling the root canals to prevent the entry of bacteria into the canals to re-infect the canals. Dental endodontics usually includes three basic steps: root canal preparation, root canal disinfection, and root canal filling. Indications: 1. Including caries, cryptic fissure, crown fracture, malformed central cusp, excessive abrasion, retrograde infection of periodontal disease, pulpitis caused by accidental pulp penetration, and pulp necrosis where the living pulp cannot be preserved. 2.Physical and chemical causes of infection of the pulp root tip, such as pulp irritation caused by poor temperature of the cushion after filling, current stimulation of different metals, endodontic treatment process of medication caused by apical inflammation, and so on. 3.Including apical lesions caused by continued development of pulpitis, failure of dry body plasticizing treatment, retrograde infection of periodontitis. 4, Degenerative changes in the pulp caused by unknown reasons, such as resorption in the root canal, pathological changes in the pulp caused by pulpite.