Removal of Extraradicular Separated Instrument by Targeted Endodontic Microsurgery Using the <scp>3D</scp> ‐Printed Guide and Trephine: A Case Report

This case report aimed to present an accurate and minimally invasive approach to retrieve a separated instrument beyond the apical foramen, using a 3-dimensional (3D) printing guide and trephine bur. A 31-year-old female patient was referred for treatment of the left maxillary central incisor, complaining that a fractured file had been pushed out of the root canal by her previous dentist approximately 2 weeks prior. On clinical examination, tooth #9 was temporarily sealed and slightly tender on percussion. Periodontal probing was within normal limits. Radiographic and cone-beam computed tomographic imaging revealed a periapical radiolucent lesion at tooth #9, with a separated instrument approximately 3 mm long extruded approximately 2 mm beyond the apical foramen and 4 mm deep in the bone. The tooth was diagnosed with symptomatic apical periodontitis. After root canal treatment, endodontic surgery was performed to retrieve the extraradicular separated instrument with the aid of a 3D printing guide and trephine bur. The root end was ultrasonically prepared and retrograde filled. The patient was asymptomatic when recalled 3 months and 2 years after the surgery, and the follow-up periapical radiograph showed successful healing of the periapical lesion. This method enables a single-step operation, completing the removal of the extraradicular separated instrument while performing osteotomy.