The University Munster model surgery system for orthognathic surgery - The digital update.

AIM: The aim of this work is to present a digital methodology of a conventional articulator based planning protocol. METHODS: The digital counterpart consists of intra-oral scans (3Shape) and a free available 3D mesh software (Meshmixer, Autodesk). The maxillary position in relation to the reference plane used and the arbitrary hinge axis were determined mathematically from landmarks on cephalometric x-rays and frontal photographs. Distances and angles were calculated to virtually mount the digital jaws in Meshmixer's wold frame. Virtual planning is done by cloning and moving the jaws according to the preliminary surgery plan. The spatial movements of the jaws are measured by attached reference points. RESULTS: This digital approach eliminate the need for articulator hardware and laboratory plaster work. It enables all planning scenarios as they are also possible with conventional plaster-based procedures. The method is time-saving, practical and cost-effective. Standard dimensions of articulators and face-bows have been incorporated in the implementation. This reduction of individual patient values puts the accuracy of the presented method within the range of conventional model surgery. CONCLUSION: Arbitrary planning will continue to have its place in orthognathic surgery, especially when digital methods can improve the overall process. The method presented can be seen as a cost-effective alternative for patients who do not require technically complex planning.