Orthognathic surgery requires rigorous preparation. This preparation can influence the outcome of the procedure.  Preparation begins more than a year before surgical intervention, with orthodontic treatment to align the dental arches. To be able to put the maxillary (upper and lower jaws) one on top of the other, the teeth must be properly aligned so that the two jaws close one onto the other, with good occlusion.  This alignment is achieved using orthodontic appliances and may take 1 to 2 years before surgery can be done. In the months before surgery, the orthodontist will assess the quality of the alignment between teeth, and make any necessary corrections.  Two weeks before surgery, surgical posts (small extensions of orthodontic appliances) will be placed by the orthodontist in preparation for the procedure. These posts will be useful during surgical intervention and in the following weeks to place the elastic, to stabilize the jaw in its new position.  Wisdom Teeth Extraction Mandibular wisdom teeth (and in some cases, maxillary teeth) are placed behind the second molars, where osteotomy surgery is performed. It is therefore difficult to extract these teeth at the same time as the orthognathic surgery. To promote good healing of the gums and bone so that it fully recovers in time for surgery, wisdom teeth should be extracted at least 6 to 12 months before orthognathic surgery.  Nutrition Some patients will meet with a nutritionist before or after surgery to ensure that the nutrient ratio is sufficient despite a soft or liquid diet during the first few days or weeks. Patients usually plan their meals at least in part before orthognathic surgery.  Softer food (pureed or liquid) can be cooked in advance to ensure good nutrition and a healthy, varied diet.  Surgical Preparation At your appointment prior to the surgery, your maxillofacial surgeon will take photos, mouth molds and radiographs to plan the surgery. This will provide a surgical simulation, which can be performed by conventional method with a mouth mold montage on an articulator, or by using a 3D technique.  A scan of your facial skeleton is also taken at this appointment and will be used for the 3D planning system. The surgeon's planning will help determine how the jaw should be moved during intervention and prepare the surgical guides that will accurately recreate these movements during surgery.