Background: As part of many orthognathic surgery procedures, a siding genioplasty is often done. While not providing any functional/occlusal benefit, it is a cosmetic procedure done for facial profile enhancement. While working in concert in some cases with a sagittal split ramus osteotomy both work to push the chin projection forward
While the sagittal split osteotomy does involve the jaw angle, it provides no aesthetic benefit unlike the sliding genioplasty osteotomy. Splitting the bone in a sagittal direction provides no jaw angle width or vertical enhancement. Any such aesthetic changes would need to be done 6 to 12 months later.
Case Study: This young male had a prior history of bimaxillary advancement surgery with a sliding genioplasty of 5mms. His plates and screws were removed six months later. While he was satisfied with his chin projection he desired jaw angle augmentation that added both vertical and width augmentation.
Because of bony jaw angle asymmetry and the need to extend the augmentation all the way up to the back end of the prior sliding genioplasty, a custom design was done. To give the jaw angles more shape the implant design added some vertical length but more substantial width.
Under general anesthesia and through his prior posterior vestibular intraoral incisions, the custom jaw angle implants were placed and positioned using the orientation tabs on the design. (arrows) Double screw fixation was placed percutaneously on both implants.
Not only does the sagittal split osteotomy not provide any aesthetic improvement to the jaw angles, it often creates irregularities and asymmetries. Putting back together the proximal and distal segments during the sagittal split procedure as well as some expected bone resorption can change the preoperative shape of the jaw angles. Such bony changes are never symmetric which is the reason a custom implant approach to such jaw angle augmentation is best.
Highlights:
1) Chin augmentation affects the front end of the lower jaw but affects nothing behind it.
2) Chin surgery is often viewed as a profile enhancement but the jaw angles are best appreciated in the front view.
3) Custom jaw angle implants are often needed after sagittal split osteotomies due to ramus bony asymmetries.
Dr. Barry Eppley
Indianapolis, Indiana