How Much Can A Custom Implant Lengthen The Chin?
Q: Dr. Eppley, I have some questions about custom jaw implants. First, can they not be made of Medpor material as opposed to silicone? Secondly, what is the limit of vertical lengthening of the chin. I have read that if you lengthen it very much you will disrupt the mentalis muscle sling. How do you determine the maximal limit?
A: In answer to your questions:
1) Medpor is a machine milled product, silicone is a poured product. Since custom implants are made out of molds from hand-carved clay designs, the implant material must be poured into a mold to be made. In addition, ,many custom facial implants designed are large with complex shapes, the use of silicone material which is very flexible makes it possible for them to be inserted through many traditional small incisions, particularly from inside the mouth. Medpor is a rigid material which would make it impossible to place many custom implants. It is hard enough to place many standard Medpor implants, the need for a two-piece design of the chin implant is an example of that material problem.
2) In my experience, the limit of vertical elongation of the chin area is a function of the skin stretch more than ‘disrupting the mentalis muscle sling’. I have rarely found the need to go beyond 10mm to 15mm and have no found it to be a problem. The key to inserting such an elongating implant in the chin area is the location of the submental incision. If you use the traditional incision location, its position will be displaced outward up on the edge of the rather than under it. Therefore, the submental incision must be moved back from the traditional location when using a custom chin implant that creates substantial vertical lengthening.
Dr. Barry Eppley