A custom jawline implant offers the most effective and powerful strategy for augmenting the lower third of the face. Designed as a single implant its wrap around effect connects the chin and the jaw angles into a confluent aesthetic effect. Since it is designed as a single implant, it is ideal to place it as such.
The ability to place any custom jawline implant as it is designed depends on its material composition as well as the thickness of the jaw angle component. Only solid silicone has the ability to be placed as a single implant due to its material flexibility and elastic deformation properties. By definition any rigid material (e.g., PEEK, polyethylene) can not be placed as a single implant when its length involves the entire jawline.
But even solid silicone can not always be placed as a single piece jawline implant. The rate limiting factor is the location of the mental nerve which creates the tightest subperiosteal tunnel location between the chin and the jaw angles. This is where the pocket has the most limited vertical height. Passing the jawline implant in a front to back direction (typically from a submental incision) requires the tallest part (jaw angle) to pass under the mental nerve without injuring it. This is usually done by folding the jaw angle portion of the implant onto itself, which makes it vertically shorter, and then passing it under the nerve.
But when the jaw angle reaches a certain thickness it can not be adequately folded over onto itself. It then becomes necessary to use am implant split approach. One technique is the midline geometric split and placing the implant in a back to front technique.
Another implant split technique is the bilateral posterior split technique which creates a three piece implant. This is done at the anterior end of the jaw angles and still employs a geometric split. This allows the chin and body part of the implant to be placed through the anterior incision and the jaw angles inserted intraorally through the posterior incisions. The geometric split allows the implant to be reliably reassembled back into a single unified implant.
The geometric split allows the jaw angles to be put back together with the body part of the implant in a reliable manner. Screw fixation of the jaw angles is then done using a percutaneous technique.
An interesting question is which geometric split technique is best when a custom jawline implant can not be placed as one piece. That depends on the size of the chin part of the implant. Larger chin components can also be a problem for passage under the mental nerve so the three piece split technique work best in these cases.
Dr. Barry Eppley