The forehead shape is very gender specific as are many facial features. These differences are well known. Men have a more complex topography to their forehead because of the prominent brow ridge that runs horizontally across it. The female forehead is smoother and flatter and lacks any prominent brow bone. The inclination of the male forehead is more backwards while the female is more vertical in profile. The male forehead typically has more prominent temporal lines coming up from the tap of the brow bone up into the forehead which crates a slightly more flat or square shape frontal. Women lack these temporal lines with a resultant more convex shape to their forehead.
Understanding these forehead gender differences are of great value when designing custom forehead implants. In designing the female custom forehead implant they are several considerations including; 1) should the brow bone area be included or not, 2) should the tail of the brow bone be excluded, 3) does the design cross the temporal lines or not, 4) how far back behind he hairline should the implant extend, 5) what and where is the thickness of the central forehead in profile, and 6) what should the shape of the forehead be from side to side.
The first thought in any forehead implant design is to establish the footprint or the perimeter edges of the implant. As a general rule the implant design should go down to the brow bones but this area would be very thin. (maybe 1.0 to 1.5mm thickness) The tail of the brow bone should be excluded if it has any prominence at all. Moving superiorly the implant should cross over the temporal line onto the fascia by at least 1 cm. (with a feathered edge of course) At its most superior part the implant should extend behind the frontal hairline by 2 to 3cms as this will allow a natural flow onto the top of the skull.
Once the implant footprint is set determining its thickness and shape is next. In profile view the inclination of the forehead can be determined by changing the visible slope of the bone. This means the implant’s thickest part will be at about 2/3s up the bony forehead right before it turns back onto the skull at or in front of the hairline. I find that thicknesses around 5mms is average but that will depend on how much the natural bony forehead slopes back. Trying to get the forehead slope vertical at its central location is the goal.
The last implant design feature is its shape from side to side. For the female this is a convex shape but that doesn’t mean it slopes in a completely linear fashion from the central thickest areas thus would create a shape that is ‘dolphin like’. Rather it is a bit more flatter across the central area before it begins its taper across the temporal lines.
An overall design rule in custom forehead implants is when in doubt…go smaller. This implant covers a large surface area which means its external effect will be greater than any linear measurement of its thickness would suggest. By adhering to this principle and applying these basic design guidelines good aesthetic improvements will result.
Dr. Barry Eppley
Indianapolis, Indiana