Expander Key Keeps Bending After Turning

Can you clarify what part is bending? This isn’t immediately apparent to me from the pictures. You started with fairly significant anterior crowding, so it seems possible that you could have suture separation without diastema formation. Have you had any follow up imaging to confirm that your suture split and your TADs are still upright?

@apollo

I will be following up tomorrow with him. CBCT should confirm the TADs are still up right.

The bendy part of the actual key he provided me with is bending everytime i try to make a turn.

@drmario

hm, should tell him.

Is everything else alright though?

@oatmeal

There was a significant amount of pain I experienced the first 3 weeks after the installation and I know what it is. I am grateful to be in contact with Dr. Won Moon himself. He advised that he does not recommend acrylic pads like you see in my MSE appliance (mine was custom made for proper fitment since my palate was narrow to start with).

Moon doesn’t recommend the acrylic because they cause tissue impingement so that’s why after every turn, it hurt so much on my palate. At this point I don’t feel anymore pain after turning but now, the key keeps bending every single time I try to turn it. And unless I’m tripping out, if you see the expander in my photos, I still have more expansion to go.

@drmario

I see. Thanks for the clarification! That does seem to suggest there is a fair amount of resistance when you turn the key. Ronald Ead and NoctilucentNikki both reported some bending of the expander framework itself, and I thought that’s what you meant. I think they both had the little wrenches to advance their MSE rather than a key like yours. If I remember right MSE-2 has a wrench and MSE-1 has a key. Maybe some bending of the metal is likely to happen regardless and in their case the wrenches are more heavy duty than the mechanism whereas your key is more malleable. Hopefully your follow-up CBCT will reveal good news!

@apollo

No, thank you for your wholesome response. Yeah I remember Ronald Ead mentioned the framework of the expander got bent itself because of the all the gruntwork it’s doing to achieve the lateral expansion.

That is very interesting and that makes a lot of sense. This must require a wrench at this point of the expansion. Following the corticotomy my orthodontist performed, the first 3 weeks, the expansion went swimmingly as there was no resistance experienced for each activation made.

I hypothesize that the wrench is now what I need because this isn’t a typical tooth-borne hyrax expander that the traditional key is used for…it’s a skeletal expander moving and separating bone. Is there a link that they sell these MSE-II wrenches in case my ortho doesn’t have it? Thank you

@drmario

The MSE-1 has a hole to insert a key. The MSE-2 has a hexagonal grip that fits a little wrench. They aren’t interchangeable. Does the mechanism still turn even though the force is bending your key, or have the two sides completely stopped advancing?

@apollo

So when I put the regular key inside the hole and push towards the back of the throat, it bends as I push it back and I cannot proceed to make that turn go all the way. It turns the key into a hook. I used pliers to reshape the key to be straight again but it keeps bending.

Can i use the wrench on this expander?

@drmario

I don’t think there’s any way to interface the wrench with the MSE-1, but even if there was, it might be counter-productive to force through whatever is preventing you from advancing further. Let us know what your orthodontist says!

@apollo

thanks i appreciate your time and input. Are you an orthodontist?

@drmario

No, I’m just interested in the MSE for my sleep disordered breathing and have read a lot about it. I still haven’t been able to find an experienced provider in my area.

If a diastema didn´t appear, does that mean all the expansion so far has been bone remodelling or teeth moving through the alveaolar bone? 

Posted by: @printfactory

If a diastema didn´t appear, does that mean all the expansion so far has been bone remodelling or teeth moving through the alveaolar bone? 

I think there can be real skeletal suture separation without a midline diastema. If the incisors are crowded and overlapping to start with, they would have to separate farther before a gap would appear. Ronald Ead saw a gap between his central and lateral incisors before a gap appeared between his central incisors, which then largely closed again on its own.

@apollo

My ortho said he is under the belief that the expander has reached its maximum expansion. He tried to turn it and he said he couldn’t turn the expansion screw with his key. Personally…I don’t believe this is true because I could still turn it, but a lot more force is required. I think the expander (as you can see in the pictures) clearly has more lateral expansion to achieve.

I think I am in complete understanding of the core difference between a traditional bone-borne MARPE appliance and the MSE. The bone borne MARPE has that Pin-type expansion screw that is typical for growing/younger patients while the MSE has that hexagonal spanner type for more heavy duty expansion for adult patients. At this stage of lateral expansion, the custom fabricated MARPE appliance has been met with a great degree of resistance to which it cannot overcome, but only MSE facilitated by a wrench could achieve. This is mainly due to the less powerful input forces.

I think my ortho screwed me with a half-baked skeletal expander. He’s got the 4 13mm TADs installed but it should have been Won Moon’s MSE. I will get a better understanding in January when I will get my aligners installed as well as a new CBCT.

For now, I ordered a ton of expander keys online and I will go through all of them to ensure that this SOB is expanded to the max. I fear that this appliance isn’t going to get me the nasal expansion I initially wanted to achieve prior to treatment.

@drmario

I can’t tell from the picture if you have a modified MSE or some other generic MARPE under the acrylic, but like I said, the MSE-1 uses a key like yours while the MSE-2 uses a little wrench. My understanding is that some practitioners prefer the MSE-1 with the key to avoid failure from applying too much force and deforming the expander structure or bending the TADs. I think the main difference with the MSE is the position of the TADs which are placed a little farther posterior to the typical MARPE. This is supposed to achieve a more parallel suture separation by opposing the resistance of the zygomatic buttresses. If you’ve expanded as far as your surrounding structure will allow, forcing it might just deform the expander rather than giving any more skeletal expansion. Ronald Ead, for example, stopped a little short of the maximum number of turns because he started feeling pain. If you aren’t satisfied with the amount of expansion, have you and your orthodontist considered trying another round with a new MSE/MARPE? With the progress you’ve made so far, you might now be able to fit an MSE without the need for modifications to the structure.

@apollo

I would guess that it’s a generic MARPE under all of that acrylic. I’ve seen plenty of photos of the MSE type I and II and it doesn’t look the same. I think the TADs are screwed straight through the acrylic and the expander is bonded to the acrylic.

Thanks for your input, I feel so lost in this. I want to achieve as much expansion (as safely as possible) and I just feel I am being shorted because of a mechanical limitation due to low input force. Yes, I agree; MSE is superior mainly due to the parallel suture separation.

Another round of MSE, huh? Do you think that’s reasonable to do 2 rounds of MSE, even though my bite is slightly different now? I haven’t discussed it yet but I will at my next appointment and I’d be glad to do it. The main reason why we didn’t proceed with the traditional MSE was because my palate was “too narrow to begin with” so he had to have the lab fabricate this custom appliance so it could fit. But now that I have gotten my palate widened, I would be able to fit what we couldn’t fit in the first place.

Update: my hypothesis was correct. I’m not done expanding. I wonder why my orthodontist was so quick to dismiss it at “it’s probably reached maximum expansion”…

i ordered more expansion keys online (way more sturdy than the Mickey mouse ones he gave me)…and I got 3 more turns in !