Commentary on Computer-Assisted Orthognathic Surgery

Abstract

For a successful orthognathic surgical procedure, an exact diagnosis and treatment plan based on the collection of clinical data are required.

Within the conventional surgical plan designing for orthognathic surgery, facial analysis is performed via facial photographs and two-dimensional radiographs. Moreover, mounted plaster dental casts on the articulator are necessary for mocking up the jaw movements and for preparing surgical splints before the operation.

This traditional method contains possible sources of random errors including occlusal plane transfer and bite wax recording, mounting of a dental cast onto the articulator, and the model surgery process (alterations between hinge axis and condylar rotation, or natural head position inconsistencies while creating the splints and lack of soft-tissue parameters) all of which may lead to imprecisions in the treatment plan process. Furthermore, it is difficult to accurately diagnose occlusal cant and any asymmetric deformity of the bony skeleton, even with precise occlusal plane recreation.

By developing a computer-assisted surgical simulation, a paradigm shift is created in surgical planning for patients suffering from cranio-maxillofacial deformities; moreover, the maxillofacial surgeons are allowed to suppress most of these inherent errors. Regarding orthognathic surgery, these protocols were greatly improved by incorporating of three-dimensional imaging techniques including CBCT or CT, dental 3D scanning, facial 3D scanning, and computer-assisted design and computer-assisted manufacturing (CAD/CAM) technology. Virtual osteotomies and simulating the orthognathic surgery on the PC and then the surgical templates or splints are virtually processed and created by a fast prototyping machine. Over the surgery, the digital intermediate splints are utilized to precisely reposition the bony segments. Even though some studies have shown that these advances correspond with better results in comparison to the standard two-dimensional planning and regular fabrication of the splints, it has some limitations for routine employment yet. On the other hand, it seems using of the navigation systems has been introduced also. It seems in the near future the using of navigation computer-assisted systems will be more popular, although according to armaments’ complexity and expensive equipment, it is limited to some academic research and training maxillofacial centers now.