If an infection and lesion at the root tip do not heal despite traditional root canal treatment or retreatment procedures, and the patient continues to experience pain with every pressure applied, “Apical Resection” (root tip resection) is a last resort. This surgery is also performed if a file remains inside the root canal that cannot be broken or removed, and the infected area behind this file cannot be cleaned. During the operation, a small window is opened in the gum to directly access the inflamed area inside the jawbone. The last 3 mm of the tooth root, containing the micro-lateral canals at the tip, is cut out (resected). A small cavity is created backward at the cut end of the root using ultrasonic probes, and this cavity is filled with a sealing material such as MTA (retrograde filling) to completely dry out the infection focus.