I just had a cosmetic operation from the long curve of mandible to the mandibular angle of mental foramen, and the osteotomy range was safe. The bisector of mandibular angle is not more than 65438±0.8cm, which will not damage the inferior alveolar nerve and blood vessels, and the ascending branch of mandibular angle will not exceed the occlusal plane. The curve drawn by the red line in the figure is the safe osteotomy range, of course, the surgeon must locate it accurately. Our patented instrument, mandibular angle variable positioning osteotome, is safe and accurate with little damage.