Three-dimensional virtual model surgery to fabricate the digital intermediate splint.

Model surgery is the classical requirement for fabricating an intermediate splint for bimaxillary surgery. However, several sources of error complicate the conventional manual technique for making an intermediate splint, and it can be difficult to reposition the cast model of the upper jaw in the desired position. Additionally, the manual procedure is time consuming and requires a lot of laboratory work. Here, we present a technical note on virtual model surgery, a computer-assisted method that combines 3-dimensional cone beam computed tomography (CBCT) of the articulator and an optical scan of the plaster cast models. A registration block is designed to match the detailed occlusal surface scan to the CBCT data. A paired-point-based registration algorithm is utilized to calculate the registration metric and to transfer the scanned plaster cast model of the upper jaw to the desired position. The detailed protocol is described, and one clinical case is presented.