Surgeon consultation for MMA - what questions to ask?

[ceylon]

What questions should I ask the OMFS at the consult? In order to both (1) determine that his skillset and experience are a good fit; and (2) steer towards the optimal surgical plan for both function and aesthetics?

I am being referred by my ENT for MMA for severe sleep apnea (CPAP not working, not a candidate for soft-tissue OSA surgeries). The surgeon is on the young side, about a decade out of OMFS residency/board certification, and seems to mostly do wisdom teeth extractions plus the odd trauma repair case. I’m concerned that he may just default to linear MMA for sleep apnea since it’s the most straightforward. If so, how can I bring up the possibility of CCW, sliding genioplasty, nose & lip effects, etc. considering he’s not a bread-and-butter jaw surgery specialist? The ENT says he’s referring me to this surgeon because he may be able to do surgery-first, otherwise braces will be a lot more expensive.

While I'm doing this for the OSA, I’d also like a good aesthetic result. I am female with recessive jaws, okay bite except for mild residual overjet/overbite after headgear and braces, normal upper tooth show, flat chin, convex profile, mild asymmetry, jaws too small for tongue, bruxism, occasional TMJ issues on right side (possibly due to jutting lower jaw forward during sleep in attempt to make more room for my tongue). Wary of philtrum lengthening and chimp-profile from straight advancement - would CCW and/or SG mitigate this? How is it determined if I'm a good candidate? Is posterior downgrafting something most OMFS are capable of? I don’t think I have the maxillary length to accommodate anterior impaction. Of course I want the optimal plan for my case, but how do you balance this with the limitation of what movements the surgeon is capable of/comfortable with?

I’d be thankful for any advice, I really appreciate the depth of knowledge on this forum. I want to maximize the value of the consult by having a good list of questions to ask before going in. I'll have a cbct done on the day, and will update afterwards.

(Note: I realize going to someone more experienced may be the obvious recommendation, but realistically speaking that may not be possible for me. There aren’t many I know of in my area since the go-to jaw surgeon retired, and I have limited funds so going to the US for surgery is probably out of reach financially. If this surgeon doesn’t seem right I’m open to other recommendations in Canada.)

[kavan]

MMA usually refers to linear advancement for sleep apnea surgery. So obviously if you're concerned about that, then that's the question to bring up.

Changing the angle of inclination of a plane is a rotation of the plane.

In general, CCW minimizes unwanted downward vertical displacements by decreasing the angle of inclination of the occlusal plane such that maxillary advancement takes place over a less steep plane. In that way, unwanted vertical displacement vector components can be minimized. Displacement over an inclined plane has both a horizontal and and vertical component.

CCW Rotation of the maxilla this way, will in turn effect a CCW rotation of the mandible to decrease the angle of inclination of the mandibular plane such that mandibular advancement (the BSSO) can also take place over a less steep plane.

Genio can also give a CCW effect. Movement is over a diagonal plane with directional displacements; outward and up.

 However, without a ceph, no one here will be able to tell you if you're a candidate for CCW or not.

[ceylon]

Thanks. I am looking for more horizontal displacement on the mandible than on the maxilla, and to minimize vertical displacement, which is why CCW seemed like the thing. When I get the cbct I suppose the occlusal plane would mostly determine whether I'm a candidate or not?

Is there any way to prevent philtrum convexity and lengthening? I see it happening with some maxillary advancement cases and not others - why?

[PloskoPlus]

Chimp lip is mainly a function of the magnitude of linear advancement and your occlusal plane angle.  The bigger the advancement, the steeper your occlusal plane, the more convex it will look.  The anterior nasal spine can be shaved down to mitigate it somewhat, but if the movements are wrong it won't help much.

Without a ceph it's not easy to tell, but it does look like your OP is moderately steep and you would need CCW rotation with posterior downgrafting (lengthening of the rear part of your maxilla). You could get some rotation by impacting the anterior maxilla, but I don't think there's much to impact in your case.  If you're lucky, CCW rotation alone may increase your overjet to the point that no linear advancement of the maxilla would be required at all.  (You may then have a problem where your upper lip and paranasal area appear sunken.)

AFAIK, NO SURGEON in Canada performs CCW-r with posterior downgrafting.  You will need to consider American surgeons.

[kavan]

Philtrum convexity is function of 'too much' max. advancement which they try to limit with CCW.  But a sleep apnea case is not an 'aesthetics only' case. But no way to predict thing without ceph and displacement proposals. Philtrum convexity is associated with the linear advancement.

2ncd photo looks like you could have CCW if it's class 2 overbite situation with recession. 3rd looks almost like anterior open bite due to the chin contour in that photo. BUT hard to tell because a CEPH is needed.

[ceylon]

You could get some rotation by impacting the anterior maxilla, but I don't think there's much to impact in your case.  If you're lucky, CCW rotation alone may increase your overjet to the point that no linear advancement of the maxilla would be required at all.  (You may then have a problem where your upper lip and paranasal area appear sunken.)

You're right, there's no excess to impact. But for sleep apnea treatment purposes, I probably would need some degree of maxillary advancement to open up the airway on top.

AFAIK, NO SURGEON in Canada performs CCW-r with posterior downgrafting.  You will need to consider American surgeons.

I was afraid of that! I will ask anyway, but I won't be surprised if the answer is no.

[ceylon]

Philtrum convexity is function of 'too much' max. advancement which they try to limit with CCW.  But a sleep apnea case is not an 'aesthetics only' case. But no way to predict thing without ceph and displacement proposals. Philtrum convexity is associated with the linear advancement.

2ncd photo looks like you could have CCW if it's class 2 overbite situation with recession. 3rd looks almost like anterior open bite due to the chin contour in that photo. BUT hard to tell because a CEPH is needed.

That's what worries me about MMA - it's a significant advancement of top as well as bottom. I must get both jaws advanced because my sleep apnea airway blockage is both top and bottom, but I really don't like the idea of philtrum convexity from that much linear advancement.

I realize the plan is dependent on what's going on skeletally, and will update with the ceph when I have it. For now I'm trying to get a foundational understanding before I talk to the surgeon.

The 3rd photo looks like that because I'm biting on a skewer to try to show OP,  so my teeth are a bit apart. I do not have an open bite normally.

[kavan]

If that stick is your OP angle, then it's about 16 degrees approx. Norms are 8 plus or minus 4.