The goal of this clinical trial is to show the effect of patient specific lateral nasal wall osteotomy to the pterygomaxillary separation during Le Fort I down-fracture.

Participants will be divided into two treatment groups. In study group, surgery planned according to the patients' indivudial anatomy and in the conventional group, surgery planned according to mean anatomical datas.

Researchers will compare patient specific lateral nasal wall osteotomy to see if it affects the pterygomaxillary junction seperation during le fort I downfracture.

The same surgical team performed the osteotomies under general anesthesia with nasotracheal intubation. Hypotensive anesthesia was applied as a standard protocol in all patients. Orthognathic surgery, including Le Fort I and sagittal split ramus osteotomy, was used to correct skeletal deformities.

Bone osteotomy was initiated on the bilateral wall of the maxilla with piezosurgery after a mucosal incision and flap elevation.Lateral nasal osteotomy (LNO) with Nievert Anderson single guarded osteotome, median septum separation with double guarded U-shaped osteotome, and pterygomaxillary junction separation with curved osteotome were performed before the down-fracture. The only difference between the conventional and study groups was the depth of the LNO. In the study group, LNO was performed at a depth of 2 mm less than the measured distance in the axial section. In the conventional osteotomy group, LNO was performed at 30 mm for females and 35 mm for males, as suggested in the literature. A curved osteotome and a mallet were used in each case to separate the pterygomaxillary junction. The down-fracture of the maxilla was performed using a hook and a bone spreader in all patients. When the maxilla was down-fractured, LNW and the pterygomaxillary separation types were assessed intraoperatively. The maxilla was stabilized in its new position by four L-shaped osteosynthesis mini-plates at the zygomaticomaxillary buttress and the aperture piriformis regions.

Inclusion Criteria: The inclusion criteria

• orthognathic surgery to treat malocclusion
• sleep apnea
• jaw asymmetry

Exclusion Criteria:

• cleft lip and palate
• previous orthognathic surgery
• rhinoplasty