Background: The shape of the lower jawline is composed of many different components that is responsible for its overall shape. The corners of the lower jaw, chin and jaw angles, are the major contributors which together creates a triangulation effect that helps define its shape. Their visibility, or lack thereof, are what drives patients to seek augmentation surgery of them.
The paired jaw angles play a major role in the shape of the jawline and is usually what patients are referring to when asking for and denoting a well defined or more square jawline. The square jawline/jaw angles term is an inaccurate one as almost no well defined jawline has a truly square jaw angle bone shape. Every jaw angle bone shape is round at its corner (intersection of the posterior and inferior borders) and the variability, which is important in the perception of its shape, is the angular relationship between their posterior and inferior jaw borders.
The high jaw angle patient is commonly perceived as one that has a vertically short ramus. (height of the condyle/sigmoid notch to the inferior border) While this can be true for some such patients, many jaw angle appearance due more to the very rounded shape of the jaw angle. Expanding the shape of the very corner of the jaw angle, what I call ‘capping the jaw angles, is often what is needed rather a dramatic or significant overall vertical jaw angle bony lengthening.
Case Study: This male desired to have more visible jaw angles but was satisfied with his chin projection and shape. The vertical length of his jaw angles was not particularly short or high and his mandibular plane angle was not overly steep. To make his jaw angles more apparent an augmentation expansion was devised based on an implant design that provided a less round jaw angle shape that added both length and width.
Under general anesthesia these jaw angle implants were placed with gentle release of the musculoligamentous attachments and screw fixation of the implants to the bone.
A capping of the jaw angle implant approach can be effective when more visible jaw angles are desired that do not require much extra width. When the musculoligamentous attachments are released this will cause the muscle to push or roll out when it is displaced by the presence of an implant which helps to create visible width also.
It is also important to recognize that as the jaw angle becomes more visible the vertical length of the face will increase as seen in the front view. This is because the creation of more visible jaw angle adds length to the back part of the jaw which drops down the angle point in comparison to its current position from the mouth corners.
Case Highlights:
1) The high jaw angle appearance patient often has reasonable ramus length but has a rounded jaw angle shape which curves inward.
2) In designing vertical lengthening jaw angle implants, derounding the bony shape of the angle is often what is needed.
3) In placing implants that expands the inferolateral border of the jaw angle it is important to release the musculoligamentous attachments but without tearing the soft tissue sling attachments.
Dr. Barry Eppley
Indianapolis, Indiana