Author Topic: Advice regarding suggested movements and other questions (added link to images)  (Read 1018 times)

SmallJaw12

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Hi. I recently consulted a couple of maxillofacial surgeons and had a few questions regarding my case and some general questions too.
Here's the link to my images with some descriptions regarding my situation- https://imgur.com/a/Z8a4IdW

The surgeons I went to suggested just a bsso advancement of about 6-7 mm and some additional advancement with a genioplasty. I had a few questions for which I would be glad for your help and advice.
(Questions about my case)
1. Is just a lower jaw advancement with the proposed movements going to be enough for me aesthetically and to improve my airway? I feel like I need some some movement of my upper jaw too as I think it's recessed. When I asked the surgeon about my upper jaw, he told me that my upper jaw isn't recessed.

2. If my maxilla is recessed, does it need significant linear advancement or not?

3. Also, what about rotation? My MPA is high, so do I need CCW rotation? If so, then do I have enough gummy smile for significant anterior impaction? Or do I need CCW rotation with posterior downgraft? Is my occlusional plane steep to necessitate a CCW with downgraft?

4. What effect would advancement or impaction of the maxilla have on the upper lip? I seem to have a short upper lip.

5. The surgeon mentioned that I would be a surgery first candidate. Do you have any thoughts about whether I'm a viable surgery first candidate or not? From what I've read, surgery first seems to be more common for underbites or perfect bites. I haven't seen many cases with surgery first for overbites, but do you notice any other details from my pictures which would qualify/disqualify me for surgery first? I also have a dental cast with me and can post pictures of that if needed.

6. My Rami sizes seem to be asymmetric. My left ramus is larger(see opg to see what I mean). What could be the cause of it and does it need to be corrected? How would they correct it?

(General questions)
7. Is there any correlation between the amount of anterior impaction and the amount of forward movement at pogonion? For example: 3 mm anterior impaction results in 'x' amount of advancement at the pogonion. How does that compare with advancement at the pogonion from a posterior downgraft?

8. Is there a limit to the amount of advancement a person can have depending on the soft tissue? I still don't understand how the large CCW movement cases are possible. Doesn't the significant stretching of the soft tissue and muscles affect the stability of such cases?

9. I've read that some people are banded after surgery and some aren't. And almost no one is wired nowadays. Does this depend on the surgeon or is there some criteria for this?

10. How stable is a downgrafted maxilla vs a normal maxilla? So if you fall down or get hit, does the grafting material shatter or something? And does this depend on the grafting material?

11. From what I understand, in cases of significant bsso advancement they use bone grafts in the mandible too. How common is this? And is there a limit to the advancement beyond which grafting is absolutely necessary?

12. Is wisdom teeth removal always necessary for jaw surgery? The surgeon told me that my wisdom teeth don't need to be removed.

13. I understand that in the presurgical orthodontics phase for class 2 bites they retrude the lower incisors and extrude the upper incisors. What about the other teeth(molars etc)? How do they correct the curve of spee?

14. In my CBCT scan, I'm not able to view my full skull, facial soft tissue and TMJ joints. But in some videos I saw online, they're able to view the full skull, the face shape and also hide different parts of the anatomy. Is this some different type of CT scan?

Hope the forum can give me advice and thanks in advance!
« Last Edit: February 19, 2021, 08:15:15 AM by SmallJaw12 »

kavan

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Firstly, I will address SOME (but not all) of your (14) questions most of which have multiple questions within the 14. But will mention that you would need to have some  familiarity with basic fundamental geometrical relationships underbelt to 'digest' or relate to information having to do with maxfax relationships.

Secondly, Because I tend to be more inclined towards what your surgeon thinks you should have rather than what you think you should have, I shall address what the surgeon is most likely trying to convey to you (single jaw surgery). For example, because I see nothing about your case that resolves to CCW, either anterior impaction or posterior downgrafting, I consider multiple permutations of questions about CCW NOT applicable to your case and hence MOOT points for me to address. However, since your questions are on the excessive side, (hardly the 'few' you say) there are plenty of them to go around for others to chime in as to the ones I consider not applicable or moot for me to answer.

1: Your surgeon is most likely conveying that your LOWER airway is narrow and that advancing the lower jaw along it's present 'line' or angle of inclination (MPA) will improve both form and function and that adding a genio (most likely a sliding genio that goes both outward and upward) will add to the improvement of both breathing and also help offset the inclinination of the MPA.

Your surgeon is looking at ANGLE RELATIONSHIPS when he tells you your maxilla is not recessed. With reference to ceph photo: https://ibb.co/BPFrrCC  he is looking at the SNA angle (approx 75 deg) which is below norm (82 ± 2°) BUT he's also seeing that that the line from point 'S' to point 'N' is approx 14 deg away from a horizont whereas norms for SNA and SNB angles are based on 7 deg away. So ADJUSTING for that involves adding 7 deg to the SNA bringing it up to 82 deg which is within the norm. He's also looking at the 'line' of your maxilla (points ANS to PNS) which is about 11 deg away from a horizont where point ANS is above point PNS. So moving 'forward' along that angle of inclination would be of NO aesthetic benefit. Another line he's looking at is a vertical that passes through where the base of your nose meets the upper lip and finding that your upper lip is pretty close to where it should be with reference to such a vertical drawn through such a point. He could also be looking at inherent problems with braces used over bridge work of the upper teeth.  He's not seeing need for anterior impaction CCW because you DON'T have ANTERIOR gum show and he's not seeing need for posterior downgraft CCW because that would give you MORE posterior gum show than you already have. Basically, he's seeing that he can improve some form and function by SINGLE JAW surgery. In essence, your surgeon is looking at a lot more than your 'thinking your maxilla is recessed' or needs to be rotated.

2: 'IF' my maxilla is recessed... What about IF you could find all the same points, lines, angle inclinations and planes etc. your surgeon is looking at as discussed above. What about that 'IF'? If not, then consider deferring to your surgeon's judgement to leaving the maxilla where it is.

Linear advancement means to advance over one's own 'line'; line defined by point's ANS-PNS and the angle of inclination that line has with reference to a horizont. (This line seen on a ceph is a cross section of a plane called the 'maxillary plane'.) 'Forward' advancement along this line (linear advancement) will have an UNWANTED--as in UNAESTHETIC-- vertical displacement vector in lines with high inclinations away from a horizont and especially so when 'forward' advancement is SIGNIFICANT.

3: Your MPA is on upper range of norm but not overly high. Your maxillary plane (line of maxilla from ANS-PNS) is about 11 degrees in CCW direction away from a horizont and your occlusal (OP) is NOT 'steep'. Those angle relationships don't relay you are candidate for CCW. Not to mention other factors that justify not moving it at all. MPA and advancement over one's MPA can be offset with a sliding genio that has outward horizontal displacement vector and upward vertical displacement vector. MOOT POINT to discuss the rest of the questions in #3 given it does look like your candidacy is limited to single jaw surgery.


4: MOOT point (for me to address). Not applicable when the angle relationships and asssesment resolve to single jaw surgery.

5: If you still have an overbite which looks to be the case, the lower jaw (single jaw surgery) can be advanced to close in on it without brace preparation and/or braces can come later after the surgery.

6: The cause of your rami assymmetry and surgical plan for correction is best asked to your surgeon.

7: MOOT. Not applicable for me to address because the question relates to CCW of upper jaw in a case where I haven't seen candidacy for it.

8: MOOT. Another question about CCW from someone who's not a candidate for CCW.

9. MOOT. Another question about double jaw from candidate for lower jaw only.

10. MOOT. Not applicable for me to address because the question relates to CCW of upper jaw in a case where I haven't seen candidacy for it.

11. MOOT. Not applicable to a candidate who is not having 'significant' BSSO advancement.

12: Not always necessary to remove. Your wisdom teeth are growing straight up. So, your surgeon is probably conveying they won't get in way of BSSO cut.

13: Correction of curve of Spee can be achieved by:

Extrusion of molars

Intrusion of incisors

Combination of both movements

14: The (pink) scan is something the surgeon has targeted to selectively take a closer look at, my guess is it would have something to do with his decision for single jaw surgery and not to cut into the maxilla.




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SmallJaw12

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Hi Kavan, thanks for your reply! :)
Yeah, 14 questions with multiple subquestions on hindsight is a lot.
Ok, yeah. I can see how posterior downgrafting would increase posterior gum show. How is posterior gummy smile treated then though? And what's the cause of a posterior gummy smile without an anterior one? I know that VME is one of the causes for a 'normal' gummy smile, which is what they treat with anterior impaction.
My concerns about whether my maxilla was recessed arose the fact that when I jut out my lower jaw I have a slight underbite. So I thought that my maxilla might be recessed too.
Also, would a 6mm advancement be enough to increase the airway volume to prevent sleep apnea in the future? I'd read a paper which which said that a minimum 10mm advancement is needed.
And sorry for all the questions. Just have a lot of them which I probably should have asked the surgeons I was consulting.

kavan

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If excess posterior gum show is from the gums being in excess as to cover too much of the back teeth, they remove some excess gum overlap. If it's from bone excess to the posterior maxilla, they remove the bone excess via posterior impaction which is CLOCKWISE rotation. However, that can be contraindicated (antagonistic to) in someone who also has a high MPA.

How many mm advancement to open airway is a function of the present size/diameter. Not knowing that and not having at my fingertips the optimal cross sectional diameter, I can't answer your question other than to tell you that a 6 mm advancement will IMPROVE it.
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SmallJaw12

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Thanks again Kavan.

kavan

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The issue here is that you have relationships to the maxilla that are antagonistic to doing much to it at all. Braces would not work (before or after maxilla surgery) because they rely on moving the tooth ROOTS and some of the roots to the front teeth are not there to move. Also it's inclination is unfavorable for good aesthetic with linear advancement. Also no excess gum show is antagonistic CCW anterior impaction, excess posterior gum show is antagonistic to CCW posterior downgraft and MPA on the higher side of norm is antagonistic to posterior impaction plus lower jaw advancement. So, your options are pretty much limited to lower jaw advancement only + sliding genio that goes outward and upward.

So, most of your questions are about moving a maxilla that doesn't have much option to be cut into and moved and is OK where it already is on the face where it doesn't have to be moved to advance out the recessive part of your face which is your lower jaw and chin which should give you some noticeable improvement.
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