Novel Reverse Zygomatic Implant Approach: Expanded Cadaveric Validation, Surgical Accuracy, and Comparison of Orbital Access Routes—Part 2
TL;DR
Guided reverse zygomatic implant placement was technically feasible and reproducible regarding implant stability in this cadaveric model, however, cortical fracture risk and incomplete prosthetic correspondence indicate that further optimization and prospective clinical validation are required before routine clinical application.
Abstract
Background: Conventional zygomatic implant placement may be technically impossible in patients with severe trismus or extensive post-maxillectomy defects because adequate intraoral access is required. This study evaluated the feasibility, accuracy, anatomical safety, and prosthetic correspondence of a novel reverse zygomatic implant inserted from the zygomatic surface toward the oral cavity. Materials and Methods: Nine fresh-frozen cadaveric heads underwent simulated Brown Class II maxillectomies. Thirty-six reverse zygomatic implants were virtually planned at positions 13, 15, 23, and 25 and placed using specimen-specific CAD/CAM drilling guides. A superior blepharoplasty approach and an inferior transconjunctival approach with lateral canthotomy and cantholysis were evaluated. Postoperative CT superimposition was used to measure linear and angular deviations. Zygomatic bone volume, implant trajectory, primary stability, complications, and correspondence with a specimen-specific polyamide verification bar were also assessed. Results: Thirty-five of the 36 implants achieved primary stability, corresponding to a technical success rate of 97.2%. Mean deviation was 2.22 ± 1.41 mm at the zygomatic entry point and 4.41 ± 1.82 mm at the intraoral emergence point. Mean angular deviation was 3.83 ± 1.71°. No statistically significant differences were identified according to implant position, laterality, surgical access route or zygomatic bone volume. Two anterior zygomatic cortical fractures occurred; one resulted in loss of primary stability. No orbital or infratemporal penetration was observed. Complete prosthetic correspondence was obtained at a median of two of the four abutments per specimen, and none of the verification bars achieved complete passive seating over all four abutments. Conclusions: Guided reverse zygomatic implant placement was technically feasible and reproducible regarding implant stability in this cadaveric model. However, cortical fracture risk and incomplete prosthetic correspondence indicate that further optimization and prospective clinical validation are required before routine clinical application.