Chin augmentation, or mentoplasty, is a common procedure that uses a synthetic implant to enhance the projection and definition of the chin. The goal of this surgery is to create a permanent, stable change to the lower facial structure. While modern surgical techniques are highly effective at securing the device, the prospect of the implant shifting or moving remains a valid concern. Understanding the mechanisms surgeons use to ensure stability, and the specific factors that can compromise it, helps address this worry.
How Chin Implants Achieve Stability
The primary method for fixing a chin implant involves placing it directly against the jawbone. Surgeons create a snug pocket using subperiosteal dissection, which means lifting the periosteum—the tough, fibrous membrane covering the bone. Positioning the implant beneath this layer anchors it firmly to the underlying bone, offering greater stability than if it were placed on top.
This tight, subperiosteal pocket acts like a custom-fit sleeve, preventing migration during normal facial movement. To further secure the device, most surgeons use surgical fixation techniques, typically involving small titanium screws or permanent sutures. These devices directly anchor the central portion of the implant to the mandible, eliminating immediate post-operative shifting.
Over several weeks, the body forms a protective layer of scar tissue, known as a fibrous capsule, around the implant. This is a normal biological response to any implantable device. The capsule helps lock the implant into its intended position, providing long-term stabilization that complements the initial surgical fixation.
Factors That Cause Displacement
Displacement can occur due to external forces or technical errors during the initial procedure. The most common cause of migration is significant external trauma to the face, particularly during the initial healing period (the first six to twelve weeks). A direct, forceful impact can overcome the temporary anchoring of early soft tissue healing, causing the implant to shift before the fibrous capsule has fully matured.
Surgical technique also influences the risk of movement. If the initial pocket created for the implant is too large, the oversized space allows the implant to move even with normal muscle contractions. Failure to use internal fixation devices, such as screws or sutures, leaves the implant reliant solely on the tissue pocket for stability, which is often insufficient.
The placement approach also influences stability. An incision made inside the mouth (transoral approach) can make it challenging to adequately secure the implant. Implants placed via this method are more susceptible to migration due to the strong, repeated contractions of the perioral muscles used for speaking and chewing.
Infection can compromise stability, as chronic inflammation disrupts normal healing and weakens surrounding tissues. In rare instances, capsular contracture—an abnormal tightening of the fibrous capsule—can occur. The scar tissue thickens and contracts, exerting pressure that may cause the implant to twist or shift out of position.
Signs of Movement and Revision Options
If a chin implant has moved, the patient will notice distinct physical changes. The most common sign is asymmetry, where one side of the chin appears different from the other. The patient may also visibly see or feel the edge, or “wing,” of the implant protruding under the skin, indicating a shift or rotation away from the bone.
Other symptoms include pain, tenderness, or discomfort, particularly when moving the mouth or jaw. Stiffness or an unnatural feeling when the lower lip moves can also indicate the implant is pressing on surrounding muscle tissue. If these signs appear, a surgeon will use diagnostic imaging, such as an X-ray or CT scan, to confirm the implant’s position relative to the jawbone.
Correcting a displaced chin implant requires revision surgery, which is often more complex than the initial procedure. During this operation, the surgeon accesses the implant, repositions it into the center of the subperiosteal pocket, and removes any hindering scar tissue. The implant is then secured with stronger fixation, such as titanium screws, to prevent future migration.
If the implant is improperly sized—too large or too small—it may be replaced entirely with one that better fits the pocket and facial anatomy. While correcting an early shift is straightforward, revision involving a long-standing implant with established, tightened scar tissue can necessitate more extensive work for a stable and aesthetically pleasing result.