How Can Bone Resorption Under A Chin Implant Be Prevented?
Q: I am interested in getting a chin implant to make my weaker chin look better. It seems like a fairly simple procedure but this bone resorption underneath the implant sort of scares me. Why does this happen? Is there any way to avoid this bone reorption if I get a chin implant?
A: The phenomenon of bone resorption under a chin implant is a much talked about finding for many decades. One of the reasons that it occurs is due to a pressure issue with the implant sandwiched between the soft tissues and the bone. While the implant pushes the soft tissue out, causing more visible chin projection, the soft tissues do apply a small amount of pressure or recoil back over time. Since the implant is not going to resorb because it is an inorganic synthetic material, that leaves the underlying bone to accomodate and relieve this pressure.
This pressure situation is really magnified with implants that are placed too high on the chin bone. This happens when chin implants are placed from inside the mouth and are not secured down to the lower edge of the bone. It can also happen from a submental chin incision approach but is much less common because it it easer to keep the pocket of the implant low. The observation that it does not occur with more contemporary anatomical chin implants is because the wings of the implant keep them from riding up higher, acting like lateral stabilizing bars. From either approach, if the implant ends above the basal bone of the chin (which is thick cortical bone) it rests on bone with a much thinner cortex. This is where bone resorption will be seen with chin implants. It is a function of bone position and is not an actual feature or result of the implant or its material composition per se. This bone resorption phenomenon (which is largely benign and not of any great signfiicance) can be completely avoided by proper implant position on the lower edge of the chin bone. This will also maximize the benefits of the horizontal projection that the chin implant provides, some of which is lost if it gets malpositioned higher as it slides up and back.
Dr. Barry Eppley