Discussion: Refining Post-Orthognathic Surgery Facial Contour with Computer-Designed/Computer-Manufactured Alloplastic Implants

It is my pleasure to discuss the article “Refining Post-orthognathic Surgery Facial Contour with Computer Designed/Computer Manufactured (CAD/CAM) Alloplastic Implants”. This is a very important topic because the skeletal mass of the face, the configuration of its bones, and the unique volumetric form thus created determine the degree of personal attractiveness favoring self-confidence and psychological health. Computer-designed alloplastic implants have drastically changed the global attitude regarding facial reconstructions and have become a reliable and irreplaceable part of the surgical armamentarium. There are some keypoints we must outline. The first one is that we must have a timeline. Does actual 3D evaluation and planning allow us to correct all the facial areas simultaneously or is it better to make a secondary assessment and esthetic improvement after a 12 months interval? The second keypoint is which is the best material to use in order to prevent complications and achieve a stable correction. The third one is about the costs: is it clinically necessary for everyone to make a second surgical step and which is the less invasive approach? The fourth keypoint is how will the grafts behave on a long-term follow-up? It is obvious that a single stage operation will prevent additional biological and surgical related costs. Taking for granted the intraoral approach, the actual possible chance is customizing our patient’s treatment in a single stage making malar, infraorbital, pyriform aperture and chin simultaneous corrections which we plan on a 3D system, creating customized implants off the shelf with hydroxyapatite granules. Though it is well accepted that combined procedures have a higher incidence of asymmetries, this bias is actually balanced from the real efficacy we achieve through surgical experience, having we created some standard values for the average surgical population. In our current practice, further 3D customized corrections in severe asymmetries, are planned after 12 months, including eventual rhinoplasty and most diffucult residual defects which, as the Authors clearly underline, are mostly located in the mandibular line. Those in the infraorbital area are easy to be treated during the first surgical approach. Is there is a “best” material? Silastic, has long been a widely used material; it is easily positioned, flexible, does not need stabilization; on the other hand, in literature it is associated to infections, dislocations, the formation of fibrous capsules, lack of integration, and in some cases resorption of the native bone itself (1-4). Porous polyethylene (Medpor®, Porex Corporation, Newman, GA) (5) is pre-shaped but can be customized manually or with 3D planning and can be easily positioned and fixed with screws. The risks associated to the use of this material include malposition, early and late onset infections, pseudo-capsules and osseous integration failure (6-10) and in few thin skin patients we observed showing of graft borders over time. PEEK in the rehabilitation of the maxillofacial area remains an advantageous and promising alternative. Nevertheless, the technical difficulty in precisely reproducing the tortuous 3D anatomy and its rigidity as described in the paper induce the surgeon to split in pieces the graft. PEEK shows excellent postoperative aesthetic and functional results and few complications such as infections or extrusions (11-13) even though it has still to be evaluated the soft tissue behavior like muscle reinsertion in the jaws area. Coral derived porous hydroxyapatite (HA) graft (Interpore 200®, Interpore Orthopaedics, Inc., Irvine, CA), which we usually graft (14-17) particularly in the infraorbital area is available in granule, and, mixed with fibrillary collagen are stable over time and are osteoconductive (4,18-19). The prosthesis requires, nevertheless, 15% hypercorrection (4). Unless uncited in the paper, and excluding fat tissue (20-22) we are exploring hialuronic acid (HA) injections that can be easily performed with no additional surgical treatment during or after the main surgery (23-25). At the moment, there is no chance to pre-plan a specific amount of material to be injected, but HA looks like the simplest and less expensive solution to those who require 3D corrections being possible to repeat, dissolve and customize multiple step injections with different G-prime (density) during the years therefore following soft tissue behavior. Talking about the costs, a single stage operation should be the future target. In terms of facility costs, in Europe the average 2 to 3 hours theatre price is about 3 to 8000 euros including anesthesiologist and still we have to add surgical expenses. Performing a 3D customized implant has an average cost of 2 to 3000 euros for each single area, depending on the material we will adapt; we must also add one or two stage online planning which means 30 to 60 minutes of interactive chat. That is another cost (surgeon time). To conclude, the paper and the literature underline that we need a detailed clinical plan because “everything will simply work out in the operating room” has been disproven. The Authors are filling the gap between art and science going towards 3D planning systems that we expect will be more and more easy to use (26-30). Our future aim is get what we need in a single stage. We also suggest a wide series of cases for every grafted material in order to achieve a surgical algorithm for a long-term follow-up that must be available for every age and defect.