Root amputation picks out what may be a portion of the root and periapical diseased tissue. Root amputation is suitable for patients with failed root canal treatment, root canal fillings that cannot be removed, curved and narrowed root canals, broken root canal instruments, fractured root tips, and chronic apical inflammation, which should be performed with internal oblique and vertical incision, conventional flap turning method, fully exposing the periapical lesion, picking out the periapical diseased tissues, and thorough debridement with a flat root surface. Root amputation is also called rhizotomy. When one of the roots of a multi-rooted tooth suffers from hard-to-heal periodontal pockets and bone resorption or severe root bifurcation lesions, root amputation can be performed to preserve the remaining roots and crowns, thus prolonging the service life of the tooth. Therefore, patients who undergo root resection must pay attention to oral hygiene in their daily life by brushing their teeth after three meals and before going to bed, and rinsing their mouths after meals.