A Novel Reverse Zygomatic Implant Approach: Step-by-Step Protocol and Cadaveric Validation for Trismus and Maxillectomy Sequelae—Part 1

Background: Severe trismus and post-oncologic maxillary defects often prevent conventional zygomatic implant placement. This study evaluates a novel implant specifically designed for reverse insertion (from the zygoma toward the oral cavity) and assesses its feasibility and accuracy in a cadaveric model. Materials and Methods: A Brown Class II maxillectomy was simulated in a fresh-frozen cadaver. Four custom reverse zygomatic implants were virtually planned and placed using CAD/CAM surgical guides. Superior and inferior orbital approaches were compared. Postoperative CT was superimposed onto the preoperative plan to measure linear and angular deviations, and a 3D-printed verification bar assessed prosthetic alignment. Results: All implants were successfully inserted with primary stability and without compromising critical structures. The superior orbital approach yielded lower deviations and better guide stability, which was reflected in the results: deviation at the zygomatic bone was 1.25 mm in the superior approach vs. 2.32 in the inferior approach, intraorally 4.7 mm vs. 7.3 mm, and angular deviation 1.85° vs. 5.63°. Despite minor distal deflection, intraoral emergence remained within clinically acceptable limits, allowing partial seating of the verification bar. Conclusions: Reverse-insertion zygomatic implants are technically feasible, anatomically safe, and compatible with fixed prosthetic rehabilitation in cases where conventional placement is impossible. Penetrating the orbit, injuring the skin or the infraorbital nerve could be possible but guided surgery seems to prevent them. A forthcoming clinical series of eight additional cases will further validate this protocol.