Alloplastic Chin Implant
The most common type of surgical chin augmentation uses a chin implant. Alloplastic implants can be used to surgically treat mild to moderate horizontal chin deficiencies, or microgenia.
Alloplastic Chin Implant
- avg. recovery
About the Procedure
There are many different options for alloplastic chin implants. An important component relates to the characteristics of the available implant materials: Silastic implants (polydimethylsiloxane) lead to formation of a fibrous capsule that surrounds the implant without distortion. It has the advantage of being able to be carved and removed if necessary. Silastic may be commercially manufactured to particular sizes and shapes with the help of computer-aided design technology. The disadvantage is the implant can cause bone resorption and exposure. Potential complications include malposition, extrustion of implant, and infection. Gore-Tex(polytetrafluoroethylene) is a pliable alloplastic implant which is more commonly implanted in the lips and nose. MEDPOR(high density polyethylene) results in limited tissue ingrowth, but has the advantage of beingrelatively resistant to infection but the disadvantage of being difficult to remove. Risks include malposition and extrusion. BoneSource (Hydroxapatite) interfaces through osseointegration, and has the advantage of being moldable. Disadvantages include exposure and infection. Polyamide mesh(Supramid) is easily cut and shaped, and allows for fibrovascular ingrowth. Polyamide mesh, however, has been found to elicit an intense foreign body response resulting in chronic inflammation. Silicone rubber is a nonporous material which does not result in fibrovascular ingrowth. Implantation leads to fibrous capsule formation around the implant itself. If the tissue overlying the implant is thinned, then extrusion may occur. Resorption has been noted to occur underneath the implant over time. Mersilene mesh(polyamide nylon mesh or polyester fiber) allows for tissue ingrowth, which helps to secure the implant. It has good tensile strength and can be well molded to the contour of the jaw. This procedure is performed either through a 2-3 cm external cut under the chin or via an intraoral approach with no external scar. There are generally two techniques for the external approach that relate to placement of the implant on the anterior mandible. Placement in the subperiostial plane has an advantage of improved fixation, but has the risk for some erosion of the bone on which it sits. Therefore, some doctors prefer to place the implant in a supraperiosteal plane which may minimize the risk of anterior mandible erosion. There are essentially two shapes for alloplastic implants; a central chin and an extended mandibular implant. Extended mandibular implants have tapered ends, which provide a smooth transition from the central mentum to the lateral mandible, preserving the natural jawline. This allows for smooth contouring and augmentation of the lateral mandible. The other added advantage in these is that the central portion can be placed supraperiosteally, lessening the risk of bony erosion and improving fixation. The three most commonly used implant shapes are the extended anatomic mandibular implant, the Flowers chin implants , and the Mittelman prejowl chin implants. The extended anatomic mandibular implant provides uniform augmentation of the prejowl area with varying degrees of central chin augmentation. The Flowers mandibular implant provides a variation in the tilt of the implant at the central mentum with a tapered extension along the mandible. The Mittelman prejowl chin implant provides variation in the size of the central mentum augmentation, with a comparable increase in thickness in its lateral extensions resulting in augmentation to the prejowl. If the implant is not placed in a precise pocket subperiosteally, the implant must be fixed to the underlying bone. This is accomplished either using titanium screws or sutures.
The goal of chin augmentation is to restore facial harmony. Chin augmentation can be used to define an underdeveloped chin or give it more prominence. As the shape of the chin is affected by the shape of the nose, chin augmentation is often paired with rhinoplasty.
What to Expect
Chin implants are a permanent solution for a recessed chin that offers increased size and projection. Here is a quick guide for what to expect before, during, and after a chin implant.
- Do not take any blood thinning medication
- Stop smoking 4 weeks before and after the procedure
- No alcohol 2 days prior
- Do not eat or drink anything for 6 hours before
- Local anesthesia with sedation or general anesthesia
- Incision made intraorally or under the chin
- Custom implant is positioned
- Incision closed with sutures
After surgery for chin augmentation (alloplastic implant or osseous genioplasty) a chin strap dressing may be placed by some Doctors to keep pressure on the implant and to improve adherence of the soft tissue back to the anterior mandible. This is typically removed between 1-3 days. Antibiotics are given to all candidates undergoing implantation. half
Candidates mild to moderate horizontal chin deficiencies, or microgenia (inadequate projection or "weak chin").
Not Recommended For
Chin augmentation is not recommended for patients with severe microgenia, labial incompetence, lip protrusion, shortened mandibular height, severe malocclusion, and periodontal disease.
Side effects from chin augmentation may include infection, hematoma (internal bleeding), shift in implant position, changes in sensation, and poor scarring. In candidates with thin skin, or a thin amount of soft tissue pad of the chin, the implant may be bothersome. Resorption of the mandible can occur with subperiosteal placement of alloplastic implants.