Background: When designing a custom jawline implant there are five areas to consider for dimensional management. These include the chin, jaw angles (2) and the body area between the chin and the jaw angles. (2) While all are important in creating the overall jaw augmentation effect, the chin area often garners the most attention given its prominent anterior projection. It may also attract a disproportionate amount of design attention if there is a prior history of chin augmentation surgery particularly if an indwelling standard chin implant is present.
Beyond the more common dimensional issues of the chin to consider in the implant design of horizontal projection and vertical length is its width. Chin width is highly influenced by chin shape of which there are two basic types, round and square. While there are variations between the two general shapes in men the square chin shape usually is preferred. There are two key elements in designing a square chin shape, both of which are violated by the current standard square chin implant styles. In these standard implants their design flaws is that width helps make for a square chin shape…it does not. How square the chin shape is (the corners) is what makes its square regardless of its width. The more square the chin corners are the more square the chin will look on the outside. The width of the square chin is largely controlled by how width the jawline is. And not matter how square the chin shape is it shield usually not violate the taper of the jawline as it comes forward. If it does the squareness of the chin can look out of place.
An interesting feature of some male bony chin shapes is the presence of the lateral tubercles. These are raised bony prominences just off the midline of chin bone that represent the paired fusion of the two lower jaw processes during development. They are commonly seen in men and only infrequently in women. The more prominent they are the more square the external chin appearance. They can also be associated with chin clefts and dimples. What they tell us is that to have a square chin appearance the chin does not have to be excessively wide to do so. Thus in the square chin design of a jawline implant keep it narrow.
Case Study: This male had an underdeveloped lower jaw which was seen in a horizontally and vertically short chin. Despite the short lower jaw he had prominent lateral bony tubercles of the chin and a visible external square shape to it. Interestingly his lower jaw looked a lot shorter/smaller in real life than it did from his 3D CT scan.
A custom jawline implant was designed that added horizontal and vertical chin projection, vertical jawline length and jaw angle width and a square chin shape.
The chin width as measured by the converging lines of the side of the jawline was just a bit beyond those lines, making it borderline too wide. But given he wanted a square chin that was wider than his natural square chin an acceptable aesthetic compromise.
Under general anesthesia and through the usual three incisional approach his custom jawline implant was inserted in a front to back direction. Given the squareness of the chin and its natural asymmetry, ensuring optimal horizontal alignment was important, so double screw fixation was used to secure it to the bone.
When seen 3 years later his jaw augmentation results shows a major improvement in his jaw shape and a more square chin.
Square chins, whether done as part of a custom jawline implant or just a custom chin implant alone, come from square chin corners that stay, as much as possible, within the line of the jawline as the two sides converge anteriorly. This is supported by observing the lateral bony tubercles of the chin in the naturally more square chin.
Case Highlights:
1) The chin part of a male custom jawline implant often had a more square and less round shape.
2) Square chin implant shapes will likely be seen if they have exaggerated designs.
3) The width of a square chin shape takes clues from the presence of bony tubercles as well as the line of width of the jawline behind it.
Dr. Barry Eppley
World-Renowned Plastic Surgeon