Clinical and radiographic outcomes of bone lid technique in endodontic microsurgery: A retrospective study.

INTRODUCTION: To compare the clinical and radiographic outcomes of the bone lid technique and conventional osteotomy in endodontic microsurgery (EMS) for teeth with an intact labial or buccal plate of bone (≥1 mm). METHODS: This retrospective study included 64 teeth from 64 patients who underwent EMS between January 2021 and July 2025. Cases were assigned to the bone lid (BL) group or conventional osteotomy (CO) group according to the surgical approach. Cone-beam computed tomography data were evaluated at baseline and at 3, 6, and 12-24 months after surgery. The primary outcome was comprehensive success, defined as both clinical and radiographic success at 6 and 12-24 months. Secondary outcomes included clinical success, radiographic success, lesion volume reduction, grayscale value changes, buccal plate of bone thickness, and alveolar arch contour. Regression models were used to identify outcome-associated factors. RESULTS: The BL group achieved greater lesion volume reduction and better preservation of buccal plate of bone thickness at both intervals (P< 0.05). Alveolar arch collapse was less frequent in the BL group at 6 months (6.3% vs. 73.1%,P< 0.05) and 12-24 months (0.0% vs. 26.3%,P< 0.05). Clinical success (asymptomatic healing) was comparable between groups at all time points (e.g., T3: 100.0% in BL vs. 77.3% in CO,P> 0.05). However, the BL group showed significantly higher radiographic complete healing rates at T2 (80.0% vs. 30.3%,P< 0.05) and T3 (100.0% vs. 59.1%,P< 0.05), as well as higher comprehensive success at T2 (90.0% vs. 54.5%,P< 0.05) and T3 (100.0% vs. 68.2%,P< 0.05). CONCLUSIONS: For teeth with a preoperative buccal plate of bone ≥1 mm, the bone lid technique provided more favorable radiographic healing and better preserved alveolar arch contour than conventional osteotomy.