The sliding genioplasty remains the workhorse procedure for significant chin augmentation. Unless a patient specifically prefers to avoid an autologous bone procedure, it is almost always preferable to reposition the chin bone itself rather than place a large volume of implant material to achieve projection. However, even with substantial sliding genioplasty movements (10mm or more), the desired degree of chin projection may not always be fully achieved.
In such cases, a secondary chin implant overlay can be applied to further enhance the augmentation. This approach raises two key considerations:
? How much additional augmentation can the soft tissues accommodate?
? Which incision route—intraoral or submental—is best?
Ideally, the sliding genioplasty has already brought the result close to the patient’s goal, with only modest additional projection needed—typically 5mm or less. Beyond projection, some male patients also seek an overlay implant to create a more square-shaped chin, emphasizing lateral rather than central width.
Surgical Considerations
The secondary chin implant can be placed via the original intraoral incision or through a new submental skin incision. Both approaches are viable and have the same advantages and disadvantages as in primary chin implant surgery.
The most important technical point, regardless of approach, is to avoid malposition:
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The intraoral route risks placing the implant too high.
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The submental route risks placing it too low.
Using the lower edge of the genioplasty fixation plate as a landmark helps guide optimal implant positioning, assuming the plate itself was properly centered. Screw fixation is essential, as the advanced bony chin edge now presents as a ledge.
Case Study
A male patient underwent a 10mm advancement sliding genioplasty, with 5cc of cadaveric bone chips grafted into the bony step-off. He healed uneventfully and experienced a dramatic improvement in his lower facial contours and overall appearance.
Six months later, satisfied but desiring a subtle additional enhancement, he elected for a secondary chin implant.
Under general anesthesia, the procedure was performed through the well-healed intraoral incision. The fixation plate was exposed, revealing significant bone overgrowth over its upper half but none over its lower half. A 5mm mandibular glove chin implant was placed over the lower half of the bone directly atop the fixation plate and secured with screws on either side.
A V-shaped wedge was removed from the center of the implant to eliminate a buckle of excess material. After placement, antibiotic powder was applied, and the incision was closed in three layers with resorbable sutures.
Technical Insights
The implant overlay concept is effective when the implant makes only a minor contribution to the overall augmentation. Positioning can be more technically challenging given the modified bony anatomy, and the implant should not be overly large. While a custom chin implant may be ideal, standard implants can still achieve excellent results.
I prefer the mandibular glove style implant, as it is vertically taller, conforms well to the bone, and offers greater surface area for secure screw fixation.
Key Points
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Secondary chin implant augmentation is a safe and effective adjunct to sliding genioplasty.
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Both intraoral and submental approaches are appropriate for implant placement, each with its own considerations.
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The soft tissue limitations of the advanced chin pad typically restrict implant size to 5mm or less.
— Dr. Barry Eppley
World-Renowned Plastic Surgeon