Lengthening face - anterior vs overall downgraft

[couchcloud]

First of all, would like to thank Kavan for all his useful information on this topic matter on the site already. I have read through most if not all of the posts I can find on the topic but still don't quite understand the following.

I am currently planning my bimaxillary surgery and am curious about the different types of downgraft. I have a short-face but do have a fair amount of teeth show. It is not full-teeth show and could still have 2-3mm of downgrafting to help lengthen the face (I will likely supplement with vertical genio).

My surgeon of course has his own plan which I will discuss when I next see him, but I want to understand as much of this as possible when I see him for an informed discussion and also have my own understanding.

A lot of advice online seems to suggest clockwise rotation as a general remedy for this (which from my understanding would be a 2-3mm anterior downgraft). But, from what I've learned from my own research, I could also get the same exact lengthening with a 2-3mm overall uniform downgraft (this just wouldn't be a clockwise rotation anymore). Is there any reason people suggest clockwise rotation specifically, is it better at combatting the issue in terms of lengthening the face? Or is this simply a poor general understanding and there is really no difference between a uniform and anterior only downgraft for short-face.

Following on from this, I am curious what are the things to take into consideration when deciding between a CW, neutral or CCW rotation given that I will add 2-3mm of height with the downgraft - just either making it a net neutral or a net rotation when combined with the posterior downgraft.

 I appreciate you will not want to make judgements on my specific case, especially without full-details etc. so I am simply asking for the things that should influence this decision, what should I be taking into account? I will give it the thought myself given my case. For example, can I expect different nasial changes depending on if I do a net CW, or a neutral? Are there other aesthetic and functional outcomes that will differ depending on the net rotation, keeping the downgraft size the same?

I hope this query makes sense

[kavan]

I'm including part of one of my other posts:

'An OVERALL maxillary downgraft elongates the ENTIRE maxilla and increases the vertical length of the face whether or not it has 0 rotation or 'net' CCW or CW. For example a 0 rotation overall maxilla downgraft elongates the entire lower '1/3rd' of the face and so do overall maxillary downgrafts with either net CCW or net CW. They ALL address the goal of more vertical length.

A 0 rotation overall downgraft would elongate down equally. One with 'net' CCW rotation would benefit someone needing more 'uptilt' to the chin area and one with net CW rotation would benefit someone needing more 'down tilt' to the chin. Although all will vertically elongate the lower face/ chin area by pushing the area down from above, the choice of net rotation would depend on whether or not the person would benefit more from more of an uptilt to the chin or a down tilt. It would also depend on whether or not the person needed a an uptilt or down tilt to the upper front teeth.'

Other than that, If you are actually getting an OVERALL down graft that spans the entire maxilla, it will elongate the lower '1/3rd' of the face. The surgeon takes into consideration if it's going to be NET CCW or NET CW. That's all I have to offer here.

[couchcloud]

I'm including part of one of my other posts:

'An OVERALL maxillary downgraft elongates the ENTIRE maxilla and increases the vertical length of the face whether or not it has 0 rotation or 'net' CCW or CW. For example a 0 rotation overall maxilla downgraft elongates the entire lower '1/3rd' of the face and so do overall maxillary downgrafts with either net CCW or net CW. They ALL address the goal of more vertical length.

A 0 rotation overall downgraft would elongate down equally. One with 'net' CCW rotation would benefit someone needing more 'uptilt' to the chin area and one with net CW rotation would benefit someone needing more 'down tilt' to the chin. Although all will vertically elongate the lower face/ chin area by pushing the area down from above, the choice of net rotation would depend on whether or not the person would benefit more from more of an uptilt to the chin or a down tilt. It would also depend on whether or not the person needed a an uptilt or down tilt to the upper front teeth.'

Other than that, If you are actually getting an OVERALL down graft that spans the entire maxilla, it will elongate the lower '1/3rd' of the face. The surgeon takes into consideration if it's going to be NET CCW or NET CW. That's all I have to offer here.

Thank you so much for this. I hadn't seen this post before. Could I further ask if a net CW/CCW or neutral rotation would affect the nose base/orientation too? And hence would be a factor in determining which the person would benefit from - or is this exclusively from the translation rather than the rotation?

[kavan]

Thank you so much for this. I hadn't seen this post before. Could I further ask if a net CW/CCW or neutral rotation would affect the nose base/orientation too? And hence would be a factor in determining which the person would benefit from - or is this exclusively from the translation rather than the rotation?

What has the most effect to the nose base is the extent of the maxillary advancement. Here is a diagram about the effect either rotation ALONE has to the nose base which is the 'ANS' (anterior nasal spine) and soft tissue of the lips depending on the rotation point.

Keep in mind that an advancement is a separate (mathematical) operation than a rotation because it is movement ('translation') along a line having an angle of inclination relative to the horizontal plane.

CW and CCW rotations are based on the rotation of a TRIANGLE as in how the lower VERTEX of the triangle will displace as a function of the rotation and also other areas along the triangle.

All of this stuff requires having elementary GEOMETRY under belt. If not there is no way to 'identify' with what is going on with basic maxfax displacements and rotations.

Illustration included.

[couchcloud]

What has the most effect to the nose base is the extent of the maxillary advancement. Here is a diagram about the effect either rotation ALONE has to the nose base which is the 'ANS' (anterior nasal spine) and soft tissue of the lips depending on the rotation point.

Keep in mind that an advancement is a separate (mathematical) operation than a rotation because it is movement ('translation') along a line having an angle of inclination relative to the horizontal plane.

CW and CCW rotations are based on the rotation of a TRIANGLE as in how the lower VERTEX of the triangle will displace as a function of the rotation and also other areas along the triangle.

All of this stuff requires having elementary GEOMETRY under belt. If not there is no way to 'identify' with what is going on with basic maxfax displacements and rotations.

Illustration included.

Hi, thanks again. I presume with anterior downgraft, the rotation is about the ANS point? When is a rotation ever around the incisor point?

[couchcloud]

I'm including part of one of my other posts:

'An OVERALL maxillary downgraft elongates the ENTIRE maxilla and increases the vertical length of the face whether or not it has 0 rotation or 'net' CCW or CW. For example a 0 rotation overall maxilla downgraft elongates the entire lower '1/3rd' of the face and so do overall maxillary downgrafts with either net CCW or net CW. They ALL address the goal of more vertical length.

A 0 rotation overall downgraft would elongate down equally. One with 'net' CCW rotation would benefit someone needing more 'uptilt' to the chin area and one with net CW rotation would benefit someone needing more 'down tilt' to the chin. Although all will vertically elongate the lower face/ chin area by pushing the area down from above, the choice of net rotation would depend on whether or not the person would benefit more from more of an uptilt to the chin or a down tilt. It would also depend on whether or not the person needed a an uptilt or down tilt to the upper front teeth.'

Other than that, If you are actually getting an OVERALL down graft that spans the entire maxilla, it will elongate the lower '1/3rd' of the face. The surgeon takes into consideration if it's going to be NET CCW or NET CW. That's all I have to offer here.

realised the stupidity of the second question so edited it away!

[kavan]

Hi, thanks again. I presume with anterior downgraft, the rotation is about the ANS point? When is a rotation ever around the incisor point?

Refer to the diagram.