Research on the precision of virtual surgical planning in two-jaw orthognathic surgery

To provide a clinical reference by evaluating the precision of virtual surgical planning in two-jaw orthognathic surgery.

Thirty consecutive patients who required two-jaw orthognathic surgery were included. A composite skull model was reconstructed using data from spiral computed tomography scan and surface scanning of the dental arch. LeFort Ⅰ osteotomy of the maxilla and bilateral sagittal split ramus osteotomy of the mandible were simulated using Dolphin Imaging 11.7 Premium. Genioplasty was performed if indicated. Virtual plan was then transferred to operation room using 3D-printed surgical templates. Frankfort horizontal plane (FHP), midfacial plane (perpendicular to the FHP through the nasion), and coronal plane (perpendicular to the FHP through the sella point) were the selected three symmetry planes.Midpoint of the contact of the maxillary and mandibular central incisors (UI, LI), and the mesio-buccal cusp of the first maxillary and mandibular molars (U6-R,U6-L, L6-R, L6-L) were the six chosen volumetric landmarks. To calculate the linear difference and overall mean linear difference (mean difference of the distance between UI, LI, U6-R, U6-L, L6-R, L6-L to FHP, midfacial and coronal plane) between simulated and postoperative models, the distance between selected landmarks and symmetry planes was measured. To calculate the angular difference and overall mean angular difference, values of the angles constructed by the occlusal, palatal, and mandibular plane to FHP and midfacial plane respectively were determined on simulated and postoperative models.

The virtual surgical planning was successfully transferred to actual surgery with the help of 3D-printed surgical templates. All patients were satisfied with the postoperative facial profile and occlusion. The overall mean linear difference was 0.81 mm (0.71 mm for maxilla and 0.91 mm for mandible); and the overall mean angular difference was 0.95° (the mean angular difference relative to FHP was 1.10°, and that relative to midfacial plane was 0.83°).

Virtual surgical planning facilitated the diagnosis, treatment planning, and precise bony segments repositioning in two-jaw orthognathic surgery.