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Background: The frequency of indwelling chin implants in patients that present for custom jawline implants occurs almost 30% of the time in my experience. This is not a surprise given the common use of chin implants for any type of lower jaw deficiency where it be moderate or severe. It is also for many patients a ‘starter’ implant for the jawline either due to a desire for a more limited procedure or not yet aware that other parts of the jawline can be augmented as well. For some their original chin implant was placed long before more complete jawline augmentation was possible.

Chin implants have been made of a variety of materials over the years, most of which have come in preformed shapes and sizes. This makes them easy to use right out of the package and ready for insertion. These materials include silicone, porous polyethylene and ePTFE. Other types of materials have been used for chin implantation in which they are ‘borrowed’ from existing approved uses in other parts of the body. One such material is mersilene, which has been historically used as a mesh for hernia repair. It can be folded into a multi layer material that can then be shaped into a hand made chin implant. (as of 2021 this mesh material is no longer manufactured)

Because of its mesh interstices, a mersilene chin implant develops extensive soft tissue ingrowth. (not bone ingrowth) This makes secondary removal challenging and puts into the same category as Medpor, another porous implant material that is well known to be difficult to remove. It is one thing to remove porous materials that are infected, where they do not have solid tissue ingrowth, as opposed to a well healed porous implant that has been in place for years.  

Case Study: This male presented for a custom jawline implant with a prior history of a chin implant twenty years previously. Placed intraorally he was uncertain what material it was. By 3D CT scan the implant material appeared to be silicone but it had an unusual shape for any preformed silicone chin implant.

A custom jawline imply design was done anticipating complete removal of the chin implant. This added to the already 6mm of the existing chin implant projection (+3mms) as well as added significant vertical lengthening to the jaw angles, corrected jaw angle asymmetry and and made for a smooth connection between the jaw angles and the chin.

During surgery through an initial submental incision the chin implant was discovered to not be silicone. Rather it was mersilene mesh with heavy soft tissue ingrowth and incorporation. Given the high position of the implant on the chin bone with the wings over the mental nerve, it was elected to not try and remove the entire implant for almost certain permanent injury to the mental nerves. Rather just enough of the mersilene mesh implant was removed to allow the chin portion of the new jawline implant to fit. This also required some material removal of the new implant in the chin area also.

In rare facial implant removal/replacement cases, it may be necessary to use a modified approach. Making the new implant fit around the indwelling implant can be done if removal of all of the indwelling implant risks injury to adjacent important structures. 

Case Highlights:

1) Primary chin implants need to be removed for a secondary custom jawline implant placement. 

2) Certain chin implant materials, such as mersilene mesh, pose considerable difficulty with removal and potential nerve injuries in the process.

3) In this case only part of the mersilene mesh chin implant was removed and the chin portion of the custom jawline implant removed to fit around it. 

Dr. Barry Eppley

Indianapolis, Indiana

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