A sliding genioplasty is a well known chin reshaping procedure. In its original and most traditionally perceived form, it is a bone cut that allows the downfractured bony chin segment to be moved forward. This creates at the front edge of the chin a stair step bone shape after the lower chin segment is moved forward. The length of this stair step is the exact amount in millimeters that the chin is moved forward.
What is also known but less appreciated is that there can be a bony step off at the back end of the osteotomy cut. As the back end of the downfractured chin segment moves forward it can leave an inverted V-shaped deformity along the inferior edge of the jawline. How significant this residual notch deformity is depends on the angle of the chin osteotomy line and the amount of its horizontal forward movement. Probably the angle of the bone cut is more significant than the amount of forward bone movement. This can easily be seen on lateral cephalometric or 3D CT scans in some postoperative sliding genioplasty patients.
For those patients that are bothered by the jawline notch deformity after a sliding genioplasty, it can be reduced or removed. The question is whether the notch should be filled in or whether the bone behind the notch should be removed to make it smooth. There are arguments to be made for both approaches. But the bone removal approach offers the most direct and assured method to obtained a smoother jawline while avoiding the use of implanted materials. Through a small submental incision, the prominent bulges off bone can be removed along the jawline by a reciprocating saw cut. This usually exposes the marrow of the bone which is covered by a hemostatic resorbable material. The submental incision usually heals very well and offers a slightly more rapid recovery than using an intraoral approach.
Dr. Barry Eppley