Gaps opening with class 2 elastics

[Jami1]

I have been in class 2 elastics for about 3.5 weeks and am noticing gaps opening in my lower teeth with a bit of shifting as well. This seems strange to me... any thoughts? I also have a power chain across the top teeth to close some slight gaps.

[SinkFullOfDinner]

Yes, that would seem unusual to me as well, if the only change was the addition of class II elastics. What you're describing sounds a lot more like the work of your lower archwire. Has that been changed recently (within the last two appointments)?

[Jami1]

Yes....went to stainless wire about 6 weeks ago but there again, my understanding is that since the stainless is more rigid than niti, there is generally less movement.

[SinkFullOfDinner]

I think that's your culprit.

My understanding (from the receiving end of a similar experience) is the initial NiTi wires are great at gradually working on rotations, unraveling crowding, and initial leveling and aligning, but they don't do much with arch shape (among other things needed later). Eventually the two arches need to match up in the shape/form that your ortho has chosen for your plan. The stiffer wires that you just started on are better at doing that, but they can create gaps initially if your target shape is rounder or wider or just different than what you started out with, or if your ortho is trying to open a little space in order to facilitate some other movement. It definitely worked that way with me, and I was surprised that gaps were even possible when overcrowding was one of the main issues to start with. I think you'll find a number of posts from people that experienced that exact same thing that you are: gaps inexplicably appearing where none existed previously. Just one of the many charming special effects of braces!