Abstract:Introduction: This study evaluated the effect of guided endodontic microsurgery using Piezosurgery and Trephine bur techniques for osteotomy and root end resection on post-surgical radiographic outcomes. Patients and Methods: Twenty-eight male patients between 18 and 45 years old who have mandibular first molar teeth need endodontic microsurgery due to failed non-surgical treatment. The selected patients were randomly divided into two groups of 14 patients according to the type of cutting tools used for osteotomy and root end resections including Piezosurgery and Trephine bur techniques. Following the guided endodontic microsurgery, an immediate, 6 and 12 months post-surgical CBCT scans were taken to evaluate the post-surgical bone healing semi-quantitatively and quantitatively. Results: First, a Fisher exact test of the healing outcome of piezosurgery and trephine bur techniques after one year follow up, showed no statistically significant differences among groups. Second, an independent sample T test analysis for the volumetric and bone density measurements following Piezosurgery and Trephine techniques at 0, 6 and 12 months. Piezosurgery had statistically significantly higher mean values for the volumetric measurements than the trephine technique at 6 and 12 months (p < 0.05). Regarding the bone density, no statistically significant difference was recorded between techniques at 6 months. While Piezosurgery had statistically significantly higher mean values than the trephine bur techniques at 12 months (p < 0.05). Conclusion: Piezosurgery techniques achieve better healing outcomes than the trephine bur technique regarding bone volume and density. KEYWORDS: Piezosurgery, Trephine-bur, Osteotomy, root-end resection and CBCT measurements.