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PURPOSE: Clinical results pertaining to osteocutaneous, Le Fort-based, maxillofacial transplantation (OLMFT) have been encouraging, however, there are no guidelines for establishing Class I facial-skeletal relation, aesthetic harmony, and functional occlusion between the donor and recipient. In fact, all reports thus far suggest some degree of facial skeletal dysharmony/malocclusion. With this in mind, we chose to evaluate the value of orthognathic principles/practice in this setting.
METHODS: An experimental cadaver study was designed using three different techniques. Six fresh human cadaver heads were obtained/dissected under MGH/Harvard Medical School guidelines. All three osteocutaneous alloflaps were harvested using a Lefort-III based design incorporating orbital floors, zygomas, maxillae, bilateral cheeks, hard/soft palate, nose, and upper lip. Each recipient was prepared bluntly mimicking a massive, bilateral orbito-maxillofacial defect [A]. The first transplant employed a technique analogous to the one used for the world’s first face/maxilla transplant. The second employed orthognathic principles/practice including; 1) impressions/stone dental cast models (donor maxilla/recipient mandible), 2) model surgery, 3) inset planning based on hybrid cephalometric tracings, and 4) a “hybrid” acrylic occlusal splint [B]. For the first two scenarios (dentate donor/recipient), “hybrid occlusion” was defined as bilateral posterior contacts with 0-2 mm of overbite and overjet, rather than the classic first molar mesiobuccal cusp-to-mesial groove relation described by Angle. In the latter case (dentate donor/recipient), computed tomography/cephalometrics were used to evaluate skeletal and dental relations [C]. The third involved an edentulous donor alloflap transplanted to an edentulous recipient using a mimic Gunning-splint to establish the vertical dimension of occlusion. MMF was accomplished using arch bars for the dentate donor/recipient and IMF screws for the edentulous donor/recipient. Five-point rigid fixation was consistent for all three cases.
RESULTS: All three operations were successful at restoring facial skeletal aesthetics comparable to those seen with autologous methods. Operative times ranged from 3.5-5.3 hours. The addition of orthognathic practice added significant labor, necessary personnel, and 2-3.5 hours depending on the donor/recipient scenario (more time required for the dentate scenario). The first allotransplant resulted in a Class II malocclusion with positive overjet (5mm) consistent to the inaugural case. The second allotransplant had a final occlusion with a small anterior open bite (1.8mm). The overjet was 1mm. There were bilateral posterior contacts and a class I skeletal profile (ANB = 2.3 degrees). In the edentulous scenario, the use of a splint facilitated alloflap fixation with a final result consistent with an orthognathic profile (i.e. consistent with a Class I skeletal pattern) [D].
CONCLUSION: These findings suggest a paradigm shift utilizing orthognathic applications could significantly improve overall facial skeletal form, soft tissue harmony and “hybrid occlusion” in maxillofacial transplant recipients. To our knowledge, this is the first study to assess the role of orthognathic principles/practice in this particular setting and therefore, from here on forward, this type of approach should be considered an integral part of osteocutaneous face transplantation for perfecting functional and aesthetic outcomes.