Purpose: The aim of the present 1-year follow-up clinical study was to assess the healing of periapical lesions using volumetric analysis of cone beam computed tomography (CBCT) images, after either filling with platelet-rich fibrin (PRF) gel or filling with combined PRF gel and bioactive glass (PRF-BG). Materials and methods: Twelve patients were divided into two equal groups, six patients each, according to how the bony defect following periapical microsurgery was filled in maxillary anterior teeth with persisting periapical lesions in root canal treated teeth. Each patient was randomly assigned to either the PRF group or the PRF-BG group. Preoperative CBCT scans were taken for each patient for baseline volumetric analysis. All surgical procedures were performed under an operating microscope by a single operator. Postoperative CBCT scans were taken for each patient after 1 year for volumetric analysis. Wilcoxon signed rank test was used to show the effect of treatment. Kruskal-Wallis test was used to compare between the experimental groups (α = 0.05). Results: For both experimental groups significant reduction in volume resulted after treatment at P = 0.028 for PRF-BG group and P = 0.027 for PRF group. No significant difference was obtained between both experimental groups regarding percentage of change in volume at P = 0.132. Conclusion: The bioactive glass bone graft material did not give a significant difference when combined with PRF, so the use of PRF alone was sufficient to achieve periapical bone healing. Schlagwörter: bioactive glass, endodontic microsurgery, platelet-rich fibrin, volumetric CBCT