Steep mandibular plane angles?

[tdawg]

As far as I know nothing can be done about them with surgery right? Would this have an effect on your occlusal plane angle as well?

I've heard noise that distraction osteogenesis can lengthen the pterygomasseteric sling although not much in the way of befores/afters and it seems reserved for serious cases involving major issues.

This is my problem. I have a mild openbite but it is exacerbated by my steep mandibular plane. In fact my x-ray is one of the few I have seen like it. Of course this complicates things because I think there is a resistance to perform the surgery needed to correct it for a few mm change in an open bite.

[Lurker25]

For future reference in case anyone would fall into the same search pattern, with no answers, that I fell into.

Here is a "lengthening" of the ramus and angle change (gonial angle) via bimax surgery. "Bilateral stepwise body osteotomies and bilateral sagittal split osteotomies (Obwegeser)" on the mandible.

https://www2.aofoundation.org/wps/portal/!ut/p/a1/jY9LD4IwEIR_DVd2gUSNtx6U-AoHfEAvpsRSSLDblCKJv17kjI-57WS-zQxwyIBr8aiVcDVp0bxvPruGCWK8SXGXJMcAWboK4vMaEQ_REMi_BNj8Px4_iOEvfgtcNVSMVXOmi2ihgFtZSiut39nBrpwz7dJDD_u-D31BJXX6Ng70yarBNq2HhqybflJR6yCbZMHcT9lzLy8vkhZ3ng!!/dl5/d5/L2dJQSEvUUt3QS80SmlFL1o2XzJPMDBHSVMwS09PVDEwQVNFMUdWRjAwME0z/?approach=&bone=CMF&classification=95b-Special%20considerations&contentUrl=srg%2F95b%2F05-RedFix%2FP410-2JawSurg%2F02_Introduction.enl.jsp&implantstype=hidden&method=Special%20considerations&redfix_url=1340701672038&segment=Orthognathic&showPage=redfix&soloState=lb&step=1&subStep=11&treatment=











EDIT: You just need to find the right surgeon who is willing to perform the procedure. The following two images are of an extreme case of course:





https://www2.aofoundation.org/wps/portal/!ut/p/a1/04_Sj9CPykssy0xPLMnMz0vMAfGjzOKN_A0M3D2DDbz9_UMMDRyDXQ3dw9wMDAx8jYEKIvEocDQnTr8BDuBoQEi_l35Uek5-EtipkY55ScYW6fpRRalpqUWpRXqlRUDhjJKSgmIrVQNVg_Lycr30_Pz0nFS95PxcVQNsWjLyi0v0I1BV6hfkhkZU-aSGAwDYYmkN/dl5/d5/L2dJQSEvUUt3QS80SmlFL1o2XzJPMDBHSVMwS09PVDEwQVNFMUdWRjAwME0z/?approach=&bone=CMF&classification=95a-TCS%2C%20Treacher%20Collins%20Syndrome&contentUrl=%2Fsrg%2F95a%2F05-RedFix%2FTCS%2FP840-Orthogn%2F01-Conventional_Orthognathic.enl.jsp&implantstype=&method=Conventional%20orthognathic%20surgery&redfix_url=1345644282821&segment=Congenital&showPage=redfix&soloState=lb&step=1&subStep=11&treatment=

[Lurker25]

Before and after animated GIF (1-2.gif). ~11° decrease (~143° to ~132°) in the gonial angle. A 0° change in the occlusal plane:





Full process animated GIF (1-4.gif):



His results are undeniable, however I think he could have used a CCW rotation (CW rotation in reference to these images) which would have made his gonial angle even smaller. Though that would put him in a near 0° occlusal plane (not ideal). Maybe if they cut his mandible a little bit lower, coupled with a counterclockwise rotation, could they have achieved a near 120° gonial angle.

[attachment deleted by admin]

[kjohnt]

That's awesome!  I've done a ton of research and I've yet to see a mid-ramus horizontal split until now.  It would seem much more appropriate for the mandible regarding CCW rotation when compared to BSSO but I assumed the masseter muscle prohibited it either surgically or recovery-wise.

I'll have to read up tomorrow

[Lurker25]

That's awesome!  I've done a ton of research and I've yet to see a mid-ramus horizontal split until now.  It would seem much more appropriate for the mandible regarding CCW rotation when compared to BSSO but I assumed the masseter muscle prohibited it either surgically or recovery-wise.

I'll have to read up tomorrow

The masseter muscle would be affected the same way as with an implant. I've read of implants increasing the ramus length by an additional 10 mm with no issues. Granted you can only go so far with lengthening before/until the masseter muscle ruptures.