PROFESSIONAL ACTIVITIES
- Professor and chair, Department of Orthodontics, College of Dentistry, Chosun University, Gwangju, Korea
- Vice President, Korean Association of Cleft Lip and Palate
- Deputy editor, Korean Journal of Orthodontics
- Associate editor, Orthodontics and Craniofacial Research
- Editor-in-chief, Oral Biology Research
Lecture Description
The surgical occlusion for orthognathic surgery should be determined by the orthodontist who will perform the postsurgical orthodontic treatment. Therefore, the surgical plan should also be determined or accepted by the orthodontists. If complete decompensation has been achieved during presurgical orthodontic treatment, surgical occlusion can be made to achieve the best possible occlusion. However, this situation rarely occurs due to hindrances caused by the buccinator mechanism and the tongue, which causes anteroposterior and transverse compensations. When presurgical decompensation is not perfect, the surgical occlusion should be determined considering the additional postsurgical decompensation. For a more accurate estimation, a 3D simulation of the orthognathic surgery is necessary, and this became popular recently. In this type of simulation, the jaws are first moved into their ideal position rather than aiming for the best occlusion. This approach focuses more on aligning the jaw bones rather than the conventional occlusion-centered mock surgery. One drawback of this jaw-bone-centered simulation is that the surgical occlusion may deviate significantly from the best possible occlusion due to occlusal interferences. These occlusal interferences will be resolved during the postsurgical orthodontic treatment, resulting in counterclockwise rotation of the mandible. Additionally, the vertical bony step (VBS) between the proximal and distal mandibular segments, which develops during the surgery, also causes the counterclockwise rotation of the mandible during the postsurgical resolution of the VBS. These counterclockwise rotations are often mistaken as relapse because they accompany the forward movement of the pogonion. However, they are normal adaptations that can be simulated. A cutting guide (stent) for Le Fort I surgery, genioplasty, and mandibular contouring surgery can be fabricated using the 3D simulation of the surgery, ensuring more accurate cutting and more symmetric contouring. This presentation will illustrate the application of these simulations with relevant cases.
