Combined orthograde 3D navigation microsurgical endodontic retreatment for the management of persistent apical periodontitis in a mandibular molar

Aim: This case report shows a combined, orthograde and 3D navigation, microsurgical endodontic treatment of an element with persistent apical periodontitis (PAP), due to an inadequate endodontic treatment and a separated instrument beyond apical foramen of the mesio-buccal canal of the tooth 3.6. A targeted minimally invasive ostectomy with 3D navigation system was performed to localize the apex and remove the broken instrument, then completing the root end management and filling. Summary: After previous renewal of the existing restoration and non-surgical retreatment, microsurgery was carried out using the Navident. CBCT dicom data and stl files obtained from intraoral scans were uploaded into the software and matched together. The preoper-ative digital planning defined the direction and depth of the ostectomy with 5.2 mm cilin-drical bone mill drill. On the day of surgery an optic support was placed adhesively at the mandibular level, detected by the Navident camera. After the calibration of handpiece and the drill, a mucoperiosteal flap was performed. The bone mill drill was guided by the navigator, conducting a selective osteotomy. The removed bone block was stored in a Hank's buffered salt solution. The root end was resected and removed around the broken instrument. After the removal of the separated instrument, the retrocavity was prepared and filled with RRM fast set putty. A collagen sponge was placed to support the cortical block. The suture was made with 6.0 Vycril. Radiological images demonstrated the healing process. 3D navigation allowed to create a precise and targeted osteotomy. The 3D navigation seems to be predictable in complex cases, requiring accurate execution technique.