Osteocutaneous maxillofacial allotransplantation: lessons learned from a novel cadaver study applying orthognathic principles and practice.

Background: Osteocutaneous maxillofacial allotransplantation is an encouraging technique for reconstruction of complex midfacial injuries (i.e., Gordon type III composite tissue allotransplantation). Although clinical results have been promising, there are no published guidelines, to date, on how to establish a functional occlusion and class I skeletal relation between the donor maxilla and recipient mandible. The purpose of this study was to use orthognathic principles and practice to improve occlusal and facial skeletal outcomes in osteocutaneous maxillofacial allotransplantation.

Methods: Three Le Fort III-based maxillofacial allotransplantations were performed, using six fresh cadavers. Each recipient was prepared bluntly simulating a massive, bilateral orbitozygomatic maxillofacial defect. The first transplant was completed according to published protocol. The second was planned using dental cast models, cephalometric analyses, model surgery, and occlusal splint fabrication. The third involved an edentulous scenario, with the donor alloflap fixated to the recipient's mandible using a mimic Gunning splint to establish the vertical dimension of occlusion.

Results: All three operations resulted in facial aesthetics comparable to those seen with autologous methods. Operative times ranged from 3.5 to 5.3 hours. The first allotransplant resulted in a class II malocclusion (overjet, 5 mm). The second recipient, with a preexisting class II skeleton, displayed a small anterior open bite of -1.7 mm, 1 mm of overjet, and a class I skeletal relationship (A-point-nasion-B-point angle, 2.3 degrees) following transplantation. The final transplant, consisting of an edentulous alloflap to an edentulous recipient, demonstrated an orthognathic profile.

Conclusion: Use of orthognathic principles and practice in osteocutaneous maxillofacial allotransplantation resulted in improved occlusion, skeletal projection, and facial harmony relative to standard technique.