It depends what movement one is wanting/getting from it.
1: A cut from chin area to back of jaw to advance the whole mandibular border segment forward is going to bring part of your back jaw angle forward with it. So there could be blunting.
2: A cut from the chin area to the back of the jaw to ONLY drop down the whole mandibular border (to elongate) won't blunt the back of the jaw angle because you're NOT displacing a segment of it forward.
A combination of both of those movements; forward advancement of whole mandibular border segment in addition to a drop down of that whole segment will also tend to blunt the back of the jaw angle because of the forward advancement of the whole mandibular border in the combination.
BOTH options can be done in the FIRST chin wing surgery.
A SECOND chin wing surgery can be devoted to moving the BACK part of the mandibular border segment that was prior moved forward, BACKWARDS again and also rotating it outwards to give sharper definition of the angle. ANOTHER bone harvest of the HIP area will be needed to do that.
There can be other combinations of cuts depending on what the person STARTS with and what they want to END UP with and/or LIMITATIONS on how much can be achieved.
Doctors who do the chin wings require a CONSULTATION where they refer you to what kind of SCAN you need so they can look at such things as high mandibular plane angle, NERVE AREA too close to the cut and prior cuts (such as those from a prior BSSO where such things relate to LIMITATIONS of what can be achieved OR predictions of success.
On a side note, I think the chin wing doctors SHOULD discuss all these combinations and LIMITATIONS on their website because this question crops up a lot and there are only so many times I can type out similar info here which they don't elaborate on.
Other option is for posters to put up CEPH X rays.
