Purpose: The purpose of this study was to develop a prediction method for advancement genioplasty that would result in accurate preoperative cephalometric planning of the osteotomy slope and that could be transferred to the patient during the surgical procedure.
Patients and methods: Serial cephalometric tracings of 20 patients who underwent advancement genioplasty were retrospectively analyzed. The osteotomy slope angle was defined as the angle between the osteotomy and a line perpendicular to the occlusal plane. The measured angle was compared with the calculated angle deduced from the horizontal and vertical genial postoperative changes.
Results: The measured osteotomy slope angle closely resembled the calculated angle.
Conclusions: The close similarity between the calculated and measured osteotomy slope angles in this study shows that simple mathematical calculations can be applied clinically to aid surgeons in achieving a more predictable result. The osteotomy slope can be determined early in the prediction stage as a calculated figure based on the desired horizontal and vertical movements of the chin and can be transferred to the patient's chin during the surgical stage.