Three-dimensional simulation of orthognathic surgery-surgeon's perspective.

Orthognathic surgery (OGS) is a powerful procedure used to correct several types of facial deformity. By altering the position of maxillary, mandibular, and chin segments after osteotomy, the facial bony structure and soft-tissue envelope can be harmonized, leading to substantial esthetic and functional improvement of facial appearance and dentoalveolar complex. Because of the meticulous nature of the bone segment movements, accurate surgical planning is imperative. OGS planning has been subject to dramatic progress. Previously, surgeons relied on two-dimensional (2D) cephalograms, photographic analysis, articulators, and plaster casts to assess the patient’s bony and soft-tissue situation. However, these methods have numerous drawbacks. 2D methods assume that every patient has a symmetrical face, which is not reflective of reality, and results in diminished planning accuracy due to bony overprojection in the frontal and lateral cephalograms. The rotational movements around the vertical axis (yaw rotation) cannot be determined in these views. In addition, articulator-mounted plaster models do not provide information about possible bony collisions in the ramus area after the movement of the mandible or the need for genioplasty procedures. With the