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Chin augmentation is a common aesthetic request for lower third of the face enhancement. Most chin augmentation patients are seeking horizontal augmentation as the primary change which is best appreciated in the profile view. But the chin is a 3D structure due to being a solitary projecting structure which has other dimensional considerations as well. 

One important aesthetic chin dimension is that of its width. The gender implications of chin width is that females usually prefer a more narrow tapered chin while males often want more chin width. Such male chin widths may also be more specific in a request for a square chin appearance. While everyone can envision what that means, few can provide the exact dimensions of how to create it.

The concept of a square chin implant has been commercially available for three decades and is the go to implant when a square chin shape is desired. I do not know the exact premise of their design but it appears it is one based on that width = squareness. The primary difference in style 1 and style 2 square chin implants is in how side they are. Based on their dimensions (G in the diagram) their widths can be from 40 to 53mms.

Width aside, which I think is a flawed premise, the actual shape of the implant is not square. It has rounded edges which are more recessed than the frontal projection of the implant. While this is wider and less round in shape than the regular anatomic chin implants, the standard square chin implant is still more round than square. That roundness effect becomes more apparent the wider the chin width is.

One of the adverse effects is trying to use width to create a square chin look is that it actually works against that effect. The wider the chin width becomes the less contact the implant has on the bone underneath it at the sides. As seen in this 3D CT scan, a wide style 2 standard square chin implant actually bends under the pressure off the overlying soft tissue at its sides making a more rounded shape even rounder. The chin just becomes wider and fatter but not more square. As a general rule when it comes to chin width you don’t want it to exceeded the tapered line of the jawline behind it. This width can be extended in custom jawline implants because the implant itself makes the whole jaw wider.

Another feature of the standard square chin implant that has an undesired effect is their angled wings. Rather than going back directly from the front edges of the implant the tails or wings angle upward. It is unclear why that is part of the design since they divert away from the edge of the jawline, which would make for a smoother transition into the jawline. This causes variable tail positioning based on where the front part of the implant is positioned on the chin. If the implant is in ideal position or a bit lower on the chin bone the severe upward angulation of the wings get near the mental nerve. If the wings are placed in alignment with the jawline the front part of the implant sits too high resulting in less projection.

How then can an implant design make for a square chin effect? Think shape and not width. As a general rule in any facial implant design it is important to be aware of the soft thickness over it. The soft tissue chin pad is thick and full of dense tissue. Thus an implant design must be over exaggerated for any specific shape effect to be seen. As a result the corners of the chin implant should be fairly square. Maybe not exactly a sharp angulated 90 degrees but no more more than 105 degrees with a rounded sharp edge. This may look too extreme when looking at an implant design on the bone but the effect will be blunted by the overlying soft tissues.

When it comes to chin width for a more square appearance, be cautious of too much width. As a general rule 35 to 37mms is at the upper edge of what is aesthetically acceptable. For most patients the range of 30 to 35mms is what is needed dependent upon the tapered lines of bony jaw width as they come forward or the side jawline lines from the implant design behind it.

Dr. Barry Eppley

World-Renowned Plastic Surgeon

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