Root canal therapy Root canal therapy (RCT) is the most common and effective treatment for endodontic and periapical diseases internationally. The principle of root canal therapy is to mechanically and chemically remove most of the infected material from the root canal and to prevent the development of periapical lesions or to promote the healing of existing periapical lesions by filling the root canal and sealing the crown. Indications Root canal therapy is indicated for teeth diagnosed with endodontic or periapical disease that require removal of pulpal tissue and removal of infection from the root canal system with the goal of preserving the entire affected tooth or root, but requires adequate periodontal tissue and bone support. In some cases, including trauma, restorative dentistry, periodontal surgery or other treatment needs, pulp removal and root canal treatment is also required. Introduction Root canal therapy is a more complex endodontic treatment that uses many instruments and steps, requiring multiple treatment steps and multiple x-rays to complete the entire procedure. Complications During and after treatment, pain and other discomfort may occur, most of which are normal. If the pain is severe, accompanied by local swelling and systemic reactions, you should follow up promptly for further treatment as appropriate. In case of complex root canals (bending, narrowing, calcified obstruction, broken instruments, lateral penetration) or other special conditions, root canal treatment will be more difficult and require the use of special equipment and materials, and the treatment time will be increased accordingly. In the case of complex root canal treatment, broken instruments may occur, and it is not required to forcibly remove the broken instruments, which can be left in the root canal for regular review.