Moving the mandible to the retruded contact position for simulating the hinge movement in virtual three-dimensional orthognathic surgery by integrating the plaster models.

The range of rotation of the mandible during virtual three-dimensional orthognathic surgery is small and may be similar to the hinge movement of the mandible. This current study offers a new method to move the mandible to the retruded contact position (RCP), a position of beginning hinge movement, during virtual three-dimensional orthognathic surgery. During this method, a three-dimensional skull model was reconstructed from the computed tomographic images in the Mimics software. Then the RCP in the patient could be obtained using Gothic arch tracer or swallowing method and was recorded using a wax plate, followed by transferring to plaster models. Subsequently, the plaster models in RCP were scanned using a dental surface scanner and imported into the Mimics software. Finally, we could move the mandible to the RCP based on the registration between the three-dimensional skull model and plaster model for simulating the hinge movement during virtual three-dimensional orthognathic surgery. This may be a small step forward for improving the accuracy of virtual three-dimensional orthognathic surgery.