What Is The Mandibular Plane Angle Of My Custom Jawline Implant Design?

Q; Dr. Eppley, For ,my custom jawline implant design ,my questions are:

Questions

What is my skull’s current bigonial width-to-bizygomatic width ratio, and what do you think will be the ideal ratio for me? What percentage does the current implant design change this ratio to? I’m hoping for the ratio to land somewhere in the 90-95% range, but I’ll defer to you on what will look the best. I think the back corners of my jaw are close to an ideal width in their current state and only need a minor augmentation, but I’d be interested to know your opinion on this. While we don’t want to add so much width that it looks weird or unnatural, we do want to add enough width to make a noticeable positive impact, *especially* in the areas nearest to the chin.
What is my skull’s current Frankfort mandibular plane angle, and what do you think will be the ideal ratio for me? What angle does the current implant design change this angle to? I’m hoping for something in the 22-25° range, but again, I’ll defer to you. I think my current jaw angle is far too high, and the current implant design appears to me like it might not lengthen the ramus enough to adequately lower this angle, but again, I’ll defer to you on what is ideal for me.

Goals:

We want the implant to “unround” my face and optimize the masculine balance of the lower face, rather than purely maximizing the size of it—all the changes should look very masculine, but also very natural, balanced and proportionate—while we don’t want to undercorrect and not add enough, we also want to avoid overcorrecting and adding *excessive* bulk. The implant should achieve 4 main things:

1)Significant vertical lengthening of my jaw: we want to lower the ramus and mandibular body to create a more masculine angle and shape. I’ll leave it up to you exactly how much to add vertically, but the result should look very masculine, yet natural.

2)Obviously by adding significant vertical length, we’ll also be adding substantial width, because of the outward sloping angle. We definitely want the implant to add an impactful amount of width, especially in the areas nearest to the chin—but let’s also be careful not to add *too much* width, because I don’t want it to look excessively bulky or boxy. Again, we want the width to look very masculine but natural.

3)Significantly widen the chin in the front, creating a strong, square chin with defined angles. The widening of the chin needs to be significant enough to stretch the skin and get rid of the puffy “carp-like” look in my lips and cheeks.

4)Horizontally lengthen the chin 4-6 mm, for the same reason—to eliminate the carp lip. If the implant adds a few mm of vertical chin length as a mere byproduct of the wraparound, I wouldn’t be opposed to that either.

A: For the purposes of custom implant design clarifications;

1) Implant designing is not like orthognathic surgery which extensively uses cephalometric landmarks. Thus we do not use any of these measurements, ratios or numbers to make a custom implant as the end goal is to make an external soft tissue change. This is not a measurable process and until someone establishes what the impact is of augmenting bone to its soft tissue effects this will continue to be more of an art than a mathematical science.

2) Implant designing must factor in a major consideration of which a patient would not be aware…. the ability to accurately and safely place it. This consideration has major influences on the design and is one that I would only be aware.

3) The first implant design is a good approximation of what the final implant design would be since I made it based on the general goals of what can be accomplished. From a chin standpoint there can be no changes to this first design given the soft tissue restrictions imposed by the prior vertical lengthening bony genioplasty. I am not even sure if those implant dimensions will even fit but I am willing to leave it that way as should some implant reduction be necessary it can always be done in surgery. I would rather keep that amount of chin implant volume in the hope that I don’t have to modify it.

4) There is some room for additional implant volume back in the jaw angles as indicated in the attached diagram. However this is the maximum amount but I am willing to do.

5) I can certainly appreciate all of your well described goals but they defy any specific measured way to achieve them. And even if we knew exactly what those measurements would be they would have to be modified if they exceeded my design specifications to be able to be surgically placed anyway. Thus we are really creating an implant design that is driven more by soft tissue limitations as well as what can be placed as a one-piece implant.

6) That being said the overall implant design is certainly going to get you closer to your stated jaw augmentation goals but how close they will do so remains an unpredictable outcome.

Dr. Barry Eppley

World-Renowned Plastic Surgeon