Objective: Model surgery is one of the most important steps in the preoperative workup for orthognathic surgery. However, in cases of complicated two-jaw surgery, manual model surgery requires many laboratory-based steps that are time-consuming and may contain potential errors. Recently, a three-dimensional virtual model surgery (3D-VMS) program (3Txer version 2, Orapix, Seoul, Korea) was introduced. The purposes of this study were to compare accuracy of the model surgery and intermediate wafer(IW) fabrication between three-dimensional virtual (3D-VM) and conventional manual methods(MM) and to present a 3D-VMS case using combined data from three-dimensional computed tomography and 3D-virtual dental casts.
Method: Twenty five patients were divided according to presence or absence of the anteroposterior movement(Groups 1 and 2) and canting correction(Groups 3 and 4) of the maxilla. After manual(MMS) and 3D-Virtual model surgery(3D-VMS), conventional IW and 3D-Virtual IW(3D-VIW) were fabricated. Another maxillary casts were mounted on the articulator using these IWs and 3D positions of them were statistically analyzed.
Results: In model surgery, although 3D-VMS was more accurate than MMS, errors of both methods were less than 1mm in all groups. In wafer fabrication, only vertical change was significant in groups 1, 2, and 3. In accuracy after model surgery and wafer fabrication, although both methods did not show significant difference, 3D-VMS itself was more accurate than MMS.
Conclusion: 3D-VMS and wafer can be an effective alternative to conventional manual methods in cases of complex orthogantic surgery.