Why Did They Do This?

[Paws917]

I've had my braces on since last July mainly to close a lot of spaces and fix my bite. Everything has been going great! I've had chains on for most of the time and the spaces are pretty much all closed up now. Yesterday, I went for another adjustment and the ortho said we are ahead of schedule, but he said the one top left back molar isn't as well aligned as he'd like. He said this can sometimes be difficult to do with chains, so he took the chains off and they put on some kind of wires along the top that are like twist ties almost. The bottoms are the donut type rubber bands I had way in the beginning. He said that if the molar he wants to shift doesn't shift by my next visit, he's going to put a rubber band on it.

Can anyone tell me what these twist tie things on top are? Why didn't they just use the donut type rubber bands they did on the bottom?

I guess you could say I'm kind of anxious about this because he said that if that upper back molar shifts on its own before my next appoint (2 mos. away), that would lop a big chunk of time off my anticipated schedule.

Thanks!