Chin Implants Treatment & Management

Chin implantation is popular because of the relative simplicity and low morbidity. In the properly selected patient, an alloplastic implant may be more appropriate than an osteoplastic technique. Alloplastic augmentation and osteoplastic genioplasty have yielded high patient satisfaction.

As with all procedures in facial plastic surgery, adequate preoperative analysis is mandatory. This analysis entails examination of the face as a whole, with specific attention directed at the chin, lips, and nose. The patient is examined from all angles, and this is accompanied by precise photodocumentation in the standard views. Face shape and length and the relationship of the chin and nose to the face are examined. The chin is analyzed for its soft tissue components and its bony structure. The chin pad is assessed, as is the size of the chin in general. Chin projection and width are noted. The position and depth of the labiomental fold are also noted. Lack of fullness in the prejowl region, which is especially pertinent in the rhytidectomy patient, is also assessed. Labial competence is evaluated. The lower lip should be posterior to the upper lip. The lower lip should also be in alignment with the most anterior projection of the soft tissue of the chin.

When a patient is considered a candidate for chin augmentation with an alloplastic implant, the proper implant shape and size is chosen. In general, avoid overaugmentation of the female patient. Women are best treated with undercorrection to circumvent removal of an implant that is perceived as too large. This is rarely the case in male patients. The choice of alloplast is usually left to the surgeon’s discretion.

Pitanguy advised 2 principles for chin augmentation. ^[10] First, the implant should be positioned at the lowest portion of the mandible; next, it must be immobilized. One approach is intraoral, in which a transverse incision is created above the gingivolabial sulcus. This incision is approximately 2.5 cm long and at least 1 cm above the gingivolabial sulcus. The dissection is performed caudally through the muscular layer, and a pocket is created to place the implant. The midline raphe of the muscle can be used to anchor the implant into place. This is achieved by creating a flap and suturing it to the orbicularis muscle.

The use of a supraperiosteal versus a subperiosteal dissection is controversial. Most surgeons probably agree and studies have indicated that supraperiosteal placement leads to decreased bony absorption under the implant. If subperiosteal implantation is performed, the dissection is performed in the midline to the symphysis and continued with a Freer elevator lateral and inferior to the mental foramina. With the subperiosteal technique, a pocket is created to secure the implant. The periosteum is then closed, and the muscles and mucosa are closed in separate layers.

An alternative approach is the submental approach, in which a 2-cm external incision is made submentally, posterior to the first submental crease. The dissection is continued to the periosteum, and a pocket is created in the midline, inferior to the mental nerves. A tacking suture secures the implant under the periosteum, and the wound is closed in layers.

A chin implant can be performed under general or local anesthesia. The procedure can be combined with other aesthetic procedures, including rhinoplasty and rhytidectomy.

A compressive dressing can be applied overnight or longer. Ice packs may be applied to prevent excess edema. The patient is monitored for the development of excessive edema, hematoma, and infection. With the intraoral approach, hydrogen peroxide oral rinses are advised. Patients are given a short course of an oral antibiotic.

The patient is seen first 7-10 days postoperatively for removal of any external sutures. Thereafter, the patient is monitored at 1 month, 3 months, 6 months, 1 year, and yearly thereafter. Postoperative photodocumentation is performed once edema has subsided.

Minor complications include postoperative edema, hematoma, and temporary lip paresthesia. These usually resolve with minimal intervention. Other risks include infection, skin changes, bony changes, and displacement. ^[11]

The intraoral and submental approaches are associated with a small risk of infection. Soaking the implant in an antibiotic solution prior to implantation may reduce this risk. In the event of infection, salvage may be attempted with the use of antibiotics. The implant can be removed to avoid unnecessary scarring in the region. Of note, infection has been reported both in the immediate postoperative period and in a delayed fashion. ^[12]

Abnormalities in chin configuration resulting from the position of the mentalis muscle after postioning of an implant have been described. This may be secondary to a deficit in muscular bulk, displacement of the origin of the muscle, elongation, or improper draping of the muscle over the implant. These problems may lead to ptosis of the chin. Alternatively, muscle contraction may occur and lead to a bunching or dimpling appearance at the chin. Displacement of the depressor muscles may contribute to these abnormalities. Any alteration in the mentalis muscle may lead to labial ectropion, in which the patient complains of loss of oral competence. This dreaded complication may reflect implant displacement or even erosion of the mandible.

Because the chin implant is placed in a dynamic region, it is subjected to micromotion due to oral and labial movements for speaking, expression, and deglutition. This may lead to bony changes under the implant. Erosion is classified as type I if it is up to 3 mm, type II if it is 3-5 mm, or type III if it is more than 5 mm. Bony absorption under the implant is perhaps the most dreaded complication following alloplastic chin augmentation and is a common complication. This has been described with silicone implants and the harder alloplasts (eg, Medpor). By avoiding the subperiosteal plane, some bony absorption can be prevented. Good positioning may also prevent this complication. Larger implants have also been associated with erosion. Erosion has been reported as early as a few months after augmentation.

Displacement is a complication of chin augmentation by implant. Implant displacement manifests as a loss of chin projection. If the displacement is lateral, the mandibular contour is altered. If the displacement is inferior, the mentocervical angle is altered with a perceived double chin. If the displacement is superior, the labiomental angle is altered, and subsequent functional changes involving the lips may occur. This includes speaking and oral competence. Additionally, superior displacement may cause erosion of the alveolar bone and dental roots. Once displaced, the implant is at risk for extrusion, especially if infected.

A literature review by Oranges et al found good results and high patient satisfaction with six different chin augmentation techniques. The investigators looked at augmentation with the following ^[13] :

• Implants - Silicone, Gore-Tex, Mersilene, Prolene, Medpor, Proplast, hard tissue replacement, porous block hydroxyapatite, and acrylic
• Osteotomy
• Autologous grafts
• Fillers - Hyaluronic acid, hydroxyapatite, and biphasic polymer
• Local tissue rearrangements
• Implants combined with osteotomy

Cosmetic outcomes for all of these options proved satisfactory. The techniques with the highest number of procedures in the chosen studies, implants (n = 3344) and osteotomy (n = 885), had complication rates of 15.7% and 19.7%, respectively. These included 2.4% of implants and 16.4% of osteotomies that were associated with transient mental nerve–related injuries. ^[13]

Chin augmentation is seemingly simple, and indeed, many patients have been treated successfully. However, analysis of the chin is more complicated than a simple visual estimate of the defect. A chin implant can be considered a failure. This may be secondary to infection or extrusion, displacement, or patient dissatisfaction. ^[14] Disfigurement is a risk following a failed implant. This can occur with the formation of a capsule, contracture and scarring, or an abnormally draped mentalis muscle.

In the event of a failed implant, treatment is removal. This requires removal of the capsule or debridement of wound in the face of infection. Implant replacement is not recommended. Rather, the patient can be reevaluated and recommended for osteoplastic genioplasty.

Placement of the implant and, specifically, which available material is most suitable for chin augmentation, is controversial. The perfect alloplastic material has yet to be developed, but currently available alloplastic implants have provided excellent results when used for chin augmentation.