The shape of the jawline is influenced by a variety of anatomic components of which the chin and jaw angles re the most recognizable. Known as the mentum (chin) and gonial angles (jaw angles) the three corners of the jawline comprise over two-thirds of its surface area. The remaining part of the jawline lies between these three corners and makes up a relatively small part of it. But these intervening sections of bone, known as the body, is what connects the chin and jaw angles and aesthetically determines if one has a linear or non-linear jawline.
Jawline linearity is what one would think it is….does the jawline have a straight connection between the chin and jaw angles or not. Some patients prefer a straight jawline (many men and almost all women) while others prefer a non-linear jawline look. (some men) In its natural state the one anatomic factor that influences jawline linearity is whether a significant antegonial notch is present.
The antegonial notch is a concavity located on the undersurface of the body of the lower jaw in front of the jaw angles. It is present in most lower jaws to some degree in both men and women. The larger the antegonial notch the more non-linear the bony jawline is. In more significant antegonial notches the development of the lower jaw shows shorter horizontal projection and less vertical jaw angle height.
In custom jawline implants one of the most design features is to obliterate or smooth out the presence of an antegonial notch. This is a key design feature that helps make for a smooth or linear jawline appearance after surgery. This can be done when only jaw angle width is needed in the design or when considerable vertical length is needed as well.
In essence any custom jawline implant design that provides effective coverage of an antegonial notch along the jawline fits on the underside of the bone. Even when only jaw angle width is needed the implant design vertically lengthens the jawline in the notch area. When vertical jaw angle length is needed the amount of vertical length is greatest in the antegonial notch. Good positioning of any custom jawline implant, regardless of the depth of the antegonial notch, requires a complete subperiosteal release along the entire inferior border from the chin back to the jaw angles.
There are patients who do prefer, albeit not many, a non-linear jawline appearance. In this type of custom jawline implant design the antegonial notch remains a topographic feature. This gives it a curvilinear inferior border shape. The design concept here is that the notch is maintained if no vertical jaw angle length is desired.
Dr. Barry Eppley