Univ.-Prof. Prof.h.c. mult. Dr. mult. Robert Sader
Department of Oral, Cranio-Maxillofacial and Facial Plastic Surgery
University Hospital Frankfurt
Frankfurt, Germany
The Evolution of Digitalization in Oral and Maxillofacial Surgery
The close interactions between esthetics and function in orthognatic surgery required very early the need of digitalization and computer-planned surgery. The surgical repositioning of maxilla and mandible of course was done because of functional reasons (occlusion, chewing, speaking), but at the same time the esthetical appearance of the patient was changed by surgery. At the beginning of orthognatic surgery it was hardly possible to explain this fact to the patient and to show him his esthetical outcome after surgery. Therefore, in 1992 the area of digitalization started by a 2D-based rendering process of the postoperative facial profile. Parallel another big step was made by the development of radiological computertomography which offered the possibility of 3D-volume rendering and surface segmentation of bony and soft tissue structures. This also enabled the production of the first PSIs (patient specific implants) in 1995 or made possible an individual planning of shape and volume of an autologous bone transplants to reconstruct continuity defects of the mandible. By this, it was also possible to determine the exact donor site for harvesting this transplant (individual transplant design) with optimized functional and esthetic results. In callus distraction osteogenesis the amount and the vector of the distraction could be calculated before surgery. These innovations made it possible to plan and to treat much more better and even more complicated malformations, scelettal asymmetries or craniofacial syndromes. Thus, surgical therapeutical concepts being based before on multi-stage surgeries based on the experience of the surgeon could then be optimized in such a way that complex corrective surgeries could be performed in only one step by a perfect backward-planning. As next step individualized treatment strategies and various remodelling techniques were realized in an integrated 3D-planning and virtual reality-simulation environment for oral and maxillofacial surgery. Nowadays this is done in clinical routine after more than 2 decades of experience and development. With these powerful visualization techniques the surgeon was enabled step by step to plan and to simulate preoperatively complex procedures for oral and maxillofacial surgery and to transfer this planning into the intraoperative situation by navigation or robotics. Specially designed cut and transformation tools in combination with 2D/3D input devices, force feedback systems and virtual reality visualization have offered a new immersive and intuitive way of surgical planning and surgical performance.
Parallel to these soft- and related hardware developments the engineering sciences created the digitally based technology of 3D-printing starting from milling, being followed stereolithographic techniques. Nowadays almost every material can be machined and can be used for manufacturing an individual 3D-body by several generative (printing) or machining techniques.
Possibilities and limits of digital surgical planning and simulation with 3D- and 4D-datasets will be demonstrated along the presentation of the history of digitalization in oral and maxillofacial surgery. The correct indication for the application of these systems are presented in selected, exemplary cases from the Frankfurt Craniofacial Workgroup.