Fig. 3

A Pre-operative image of three-dimensional craniofacial skeletal and skin models with midsagittal plane. The more prominent left zygoma (indicated by arrow) in relation to the right zygoma (indicated by arrowhead) reveals the asymmetric configuration. Red line for midsagittal plane; white for craniomaxilla; light blue for mandible; transparent yellow for facial skin. B Three-dimensional (3D) surgical simulation made on the maxilla (purple pink) with preoperative mandible (dark blue). The computer-assisted surgical guides, including interocclusal wafer (yellow; indicated by arrow) and Y- and zygoma-guide (dark ivory; indicated by arrowheads) were designed by 3D cephalometry and CAD/CAM technique for bimaxillary orthognathic surgery. Red line for midsagittal plane; purple pink for postoperative maxillary segment; dark blue for preoperative mandible; gray and dark ivory for Y-guide. C The asymmetric and more prominent zygoma on the left side (transparent light green; indicated by arrow) was superimposed with the mirrored right zygoma to left (yellow) after initial cutting on the right zygoma (dark ivory; indicated by arrowhead) based on the treatment plan. Red line for midsagittal plane and used for mirroring; purple pink for postoperative maxillary segment. D The double osteotomy lines (gray planes; indicated by arrows) were placed on the left zygoma (transparent light green) for the simulated reduction malarplasty to produce the symmetrical and balanced zygoma based on the treatment plan and the superimposed mirror image of right zygoma (yellow). Red line for midsagittal plane, used for mirroring; purple pink for postoperative maxillary segment; mirrored right zygoma to left side (yellow); right zygoma with zygomatic cuts (dark ivory). E The draft of the surgical guide (pink; indicated by arrows) was designed to have double osteotomy lines (gray bent planes; indicated by asterisks) and fixation screws (yellow cylinder 1; indicated by black arrowhead) and a reference hole guide (yellow cylinder 2; indicated by white arrowhead). Right zygoma (dark ivory); left zygoma (light green). FThe final desgin of the CAD/CAM-based surgical guide (indicated by arrows) for reduction malarplasty with cutting slots for osteotomies (indicated by saw blade), fixation holes for stabilizing the device with screws (indicated by white arrowhead), a reference hole guide (indicated by arrowhead) for the placement of the guide, and the window opening (asterisk) to check how well the device fits to the zygomatic bone surface. G and H The morphological comparison of zygoma (indicated by arrowheads) after the simulated reduction malarplasty by our new development (in Fig. 3G) and the traditional technique (in Fig. 3H). The osteotomized zygoma of traditional technique in Fig. 3H was moved to the extent that it could match the zygomatic surface made by our reduction malarplasty in Fig. 3G. I An intraoperative view of a CAD/CAM surgical guide placed in situ with osteotomy slot (indicated by two white arrowheads and guided by saw blade), fixation screws (arrow) and reference guide pin (black arrowhead) before performing the reduction malarplasty