Module 4 Prompt 2

[Chad Carter (Course Director)]

Chinyere,

Good question. This has to do with what is possible with surgery. A LeFort setback is not a real possible procedure. Thankfully in this patient’s case she can tolerate the mandibular advancement with her skeletal and ethnic features.

Does that make sense? We have to work in the confines of what the surgeon can actually accomplish. (I can go in more detail if you like about LeForts – I wrote a little post about it recently)

Keep it up!

[Chinyere Mbadiwe]

Thank you so much!

It makes sense now.

If you can share the post that you wrote about le fort, it will be great.

[Chad Carter (Course Director)]

Chinyere,

Here is quoting the post that was from another question where I talked about LeForts

“LeForts come in all shapes and sizes. A posterior impaction is indicated when their is a steep palatal plane. This shows excess vertical bone in the posterior of the maxilla – the surgeons have to have something to cut down in order to do the impaction. I look at this case and think of a multipiece LeFort with anterior downgraft splitting with the posterior impaction. The multipiece will help treat the asymmetry.

KEY THING: Don’t forget that there is no such thing surgically as a straight up or down LeFort. Once the surgeons do the downfracture they will have about a 2mm advance just to be able to clear the pterygoid plates. Also even though technically a LeFort “setback” is possible (cutting out a ridge of the palate) it’s not realistic. I’ve worked with over a dozen orthognathic surgeons and I’ve met only one that did the surgery one time (in a very long career) and he said he’d never do it again.”

[Pegah Kamrani]

Hi Chad!

Can you confirm the effect of a posterior impaction on the maxillary incisor display and the anterior occlusal plane in general? Do we want to impact posteriorly when incisor display is inadequate and there is an AOB? Like in case 1, say incisor display is adequate but posteriorly there is vertical excess, will it impact incisor display significantly? I do understand if posterior vertical is good and it is an anterior issue only we can just do an anterior downdraft (without posterior impaction). Curious to hear your thoughts on this so I know when to consider posterior impactions going into test day!

[Chad Carter (Course Director)]

Pegah,

There are times when the surgeons and I plan single piece LeFort I with posterior impaction.

Couple of effects:

1) There is realistically about a 2mm advance of the maxilla – just as consequence of down fracture and clearing interference of plates.

2) In our Virtual Surgical planning we will maintain the maxillay central incisor edge at the same vertical position.

3) Clockwise rotation of the maxilla when it’s all a posterior impaction does directly change the maxillary incisor SN-U1 angle just because the maxilla has moved as a complex.

So considering all of those three factors it ends up being pretty much a wash for the incisor display. So there is no significant change in incisor display. The caveat here is make sure your patient gives you there FULL smile before surgery and not a posed one (not something I would worry about for boards but as a clinical pearl). We all know it’s not fun to have a patient with a posed smile and then later find out their true animation is something different.

Good luck!

[Pegah Kamrani]

thank you! very helpful!