Background: Chin implants are well known to induce a variety of tissue reactions around the implant site. A surrounding encapsulation of scar tissue is always seen as occurs in every synthetic implant placed in the body. ‘Bone resorption‘ is often cited as an adverse reaction to chin implants but this is a misinterpretation of the actual biologic response that has occurred. It is more accurately described as a limited and passive bone remodeling as a response to the recoil of the expanded tight chin pad tissues now overlying the implant. It is, in effect, a pressure relief.
Some limited bone overgrowth around the edges of the implant is also not uncommonly seen. This occurs because the implant is placed in a subperiosteal location from which a limited osteogenic response is seen from the disturbed periosteal layer. It is actually rather remarkable that bone would grow up over portions of the implant given that it is a synthetic material. But this speaks to the osteogenic potential of the periosteum. But when such a bony overgrowth is seen it is limited to just the edge of the implant, usually the lower edge.
Case Study: This 35 year female had an anatomic chin implant placed eight years previously. While she liked the general chin augmentation effect, there were several aesthetic issues that developed from it that she didn’t like. The implant had some asymmetry to it with the left wing higher than that of the right. There were also multiple indentations that had developed over the soft tissue chin pad that were present at rest and became magnified when she smiled.
Under general anesthesia and through her existing submental incision, dissection was carried down to the chin bone. Initially the chin implant could not be found as only bone could be seen.Tapping on the chin bone had a hollow sound to it. It was suspected that bone had overgrown the bottom edge of the implant and its outer layer was chipped off with an osteotome over a small area to reveal the implant underneath. Continuing to remove the bone overgrowth eventually revealed that the entire implant was completely encased in bone including over the small lateral wings of the implant. The total bony ovegrowth was removed and the implant extracted. All edges of the bony overgrowth down to normal bone was removed. The implant was re-inserted and position in a midline neutral position and secured with double microscrew fixation to prevent implant rotation and recurrent asymmetry.
Complete bony overgrowth of an extended chin implant is a tissue reaction that I have not seen occur. Partial bony overgrowth occasionally occurs but never complete bony encasement. Such a bony reaction to the implant could be the source of the overlying soft tissue chin pad indentations due to tethering into the tissues. It remains to be seen if removal of the bone improves these indentations.
It is important in treating chin implant asymmetry that any impedance to the wings of the implant be released/removed to allow the total implant to have achieve a completely horizontal orientation. Usually this involves a release of the surrounding scar capsule. In this case it involved all raised bony edges.
Highlights:
- Chin implants often induce local tissue reactions including bone overgrowth.
- Complete bony encasement of a silicone chin implant is not an implant reaction that I have seen previously.
- Chin implant asymmetry correction requires that all surrounding bony overgrowth must be removed.
Dr. Barry Eppley
Indianapolis, Indiana