The angle of the mandible is at the lowest points under the earlobes. The excessive protrusion or outward expansion can form a square-shaped face. During the procedure, Dr. Chuang will make a 3–4-cm incision in the lower gum, subperiosteally detach the masseter muscle and other soft tissues from the mandible, and then, use a high-speed electric sawing system with an oscillating saw to resect and remove protrusive angles in a curvature alignment. The range of bone resection is approximately 2 cm anterior and posterior to the angles, and the average reduced thickness is 1–1.5 cm. Other uneven surfaces after bone resection can be smoothed out by the shaving osteotomy procedure to get a symmetric result on both sides. The goal of this procedure is softening and smoothing the jawline contour in the side view and removing the square-shaped angle protrusion; however, slimming the face in the front view alone has a limited effect, and the average reducible width on each side is only approximately 0.5 cm. Therefore, this surgery is suitable only for patients with mild to moderate protrusive angle of the mandible but not for those with severe square-shaped faces.