Endodontic Treatment Failure

The goal of this clinical trial is to evaluate the surgical accuracy and healing outcomes of endodontic surgery performed with the assistance of a 3D-printed static surgical guide in patients requiring apicoectomy. The main questions it aims to answer are: 1. What is the level of positional and angular accuracy of the actual root-end resection compared to the virtual planning when utilizing a static surgical guide? 2. What are the postoperative pain and swelling levels reported by patients at 1, 3, and 7 days after undergoing guided endodontic surgery? 3. What are the clinical success rates and CBCT-based radiographic healing outcomes at 6 months postoperatively? Participants will: * Undergo a preoperative digital workflow combining CBCT data and intraoral surface scans to design a customized static surgical guide. * Undergo targeted endodontic surgery where a 4.5-mm trephine bur is guided through the static template to perform the osteotomy and a 3-mm root-end resection in a single step. * Receive retrograde root-end cavity preparation via ultrasonic tips and root-end filling using calcium aluminosilicate bioceramic paste (Well-Root PT). * Complete self-evaluation forms regarding pain and swelling on postoperative days 1, 3, and 7. * Return for follow-up examinations at 1 week (for suture removal) and at 6 months for definitive clinical evaluations, as well as follow-up multi-planar CBCT imaging to evaluate both periapical bone healing and surgical accuracy via superimposition with the baseline preoperative plan.