Lip incompetence; difficulty getting the lower lip to meet the upper lip and STRAIN in the attempt, is usually a function of the chin ORIENTATION for example chin bone being too long in vertical direction and too backwards in horizontal direction. It's basically mechanical inefficiency due to the orientation of the lifting mechanism. The lifting mechanism is the mentalis/ CHIN MUSCLE and it gets more efficient at lifting the lower lip when the orientation is closer to a VERTICAL than when it's oriented DIAGONALLY BACKWARDS. So, basically,lifting your lower lip straight up to meet your upper lip would be EASIER if the LIFTING MECHANISM; the mentalis muscle were not oriented so much diagonally backwards.
Your chin is oriented DIAGONALLY BACKWARDS which is consistent with a complaint of lip incompetence (mentalis strain when trying to lift lower lip to meet upper lip). For that reason
the displacment to it which would tend to COUNTER its present orientation would be a movement that is:
a: horizontally forward
b: vertically UPWARD as in to shorten.
That would be done via a diagonal cut where when the chin is SLID 'forward' along the diagonal cut, the 2 'vector' displacements with that are; 'a' and 'b' as stated above.
In essence, the explanation above is consistent with what a sliding genio usually does; a diagonal cut is made, along which the chin is slid forward along the cut and the individual displacements broken down into 'horizontal' and 'vertical' are horizontally forward to advance out chin and vertically upward to be shorter.
OK, it's possible you could get by with just a sliding genio. But also possible to have revision surgery with CCW to maxilla which would allow the lower jaw to be advanced out more so that the extent of genio would be LESS than if done alone. However, even so, revision surgery with CCW would not really compensate for the excessively high orientation of the mandibular plane. But once you entertain option of revision surgery, you need a really GOOD guy and the suggestion here for that is usually to seek out a consult with Gunson in the event you want to entertain the option of REVISION SURGERY. (But don't bother with him if it's only the chin genio you want.)
As to your PRIOR doctor, Behrman, you must write him a DEMAND letter requesting your surgical records. He could be hiding something (disclosure of whether or not it is true what he told you was true) given he refused to speak to you. You need to obtain your surgical records with him so the revision surgeon has them.
See a prior LAW SUIT against the guy:
https://cases.justia.com/new-york/other-courts/2015-2015-ny-slip-op-32205-u.pdf?ts=1448057576Also, it appears that his negative reviews are consistent with his MISHAP with your case followed by refusal to discuss the problems it resulted in with you.
https://www.ratemds.com/doctor-ratings/48578/Dr-David-Behrman-NEW+YORK-NY.htmlDon't bother with him any more other than to demand your surgical records from him.