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The use of standard chin and jaw angle implants can be an effective approach for many male jaw augmentation patients. But as three separate implants it does not create a controlled linear shape to the jawline due to the lack of connectivity between the implants. As a result some standard jaw augmentation patients will graduate to a custom jawline in which it not only creates a smooth linear jawline but also provides control over the chin and jaw angle dimensions.

While the design of a custom jawline implant is easily performed on paper or a computer screen doing so in surgery poses more challenges. Unlike the placement of the initial standard implants, in which the tissues are unscarred, existing implants are encased in scar or an enveloping capsule. This is what really holds implants in place long term and consists of a dense layer of scar that is quite different than normal tissue. This scar tissue must be released and/or removed for the placement of a new implant particularly one that now must connect the front and back ends of the lower jaw.

While such capsular releases/removals are common in almost all facial implant replacements, going from standard jaw implants to a one piece custom jawline implant puts the mental nerve at risk. The exit of the inferior alveolar sensory nerve of the lower jaw, which then acquires the mental nerve name, occurs between the 1st and 2nd premolars at the midway point in the height of the jaw. Its lower height of exit on the bone and the much height of the jaw angle portion of the implant makes its safe passage under the mental nerve precarious.

Thus in existing jaw implant removals it may not be safe to try and place a custom jawline implant as a single piece in a front to back direction of placement as is traditionally done. To get around this mental nerve limitation a split implant placement technique can be used. With a midline split the custom implant can be placed in a back to front direction. This allows the more narrow chin and body portion of the implant to be safely passed under the mental nerve location. The midline split through the chin is a geometric split so its fit back together is precise.

While I don’t like to separate a wrap around jawline implant into two pieces the risk of permanent mental nerve numbness will over ride that implant placement concern. While the need to do this maneuver may be suspected before its surgical placement it is ultimately an intraoperative judgment.   

Dr. Barry Eppley

World-Renowned Plastic Surgeon

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