Endodontic microsurgery is important for preservation of natural teeth with symptomatic apical periodontitis when conventional endodontic treatment is neither feasible nor effective. The thick buccal cortex, poor visibility, and potential neurovascular complications can make microsurgical procedures of mandibular second molars infeasible. With the aid of cone-beam computed tomography, the bony lid approach was applied in 10 cases of endodontic microsurgery of mandibular second molars at the VIP Center, Hangzhou Stomatology Hospital between 2019 and 2020. In all cases, the clinical and radiographic findings at the 24- or 36-month follow-up revealed complete healing of the periapical lesions. The bony lid technique contributed to precise root-end localization and helped avoid excessive postoperative pain or unfavorable healing that occurred in cases of excessive alveolar bone resection. Some clinical tips on preserving the cortical bone, obtaining precise access, and improving surgical efficiency have been proposed in this report.