The purpose of the study is to evaluate peri-radicular healing after root-end surgery using Leukocyte and Platelet Rich Fibrin. The study population includes patients diagnosed with persistent periapical pathology and scheduled for Endodontic Microsurgery at the University of Pennsylvania School of Dental Medicine, Department of Endodontics. Patients undergoing routine endodontic microsurgery and who meet the inclusion criteria will be given the opportunity to opt in to receive L-PRF in the osteotomy site to promote bone formation. Healing will be assessed radiographically and clinically at six, twelve, eighteen, and twenty-four months.