Should we pay for braces?

I have a 14 yr. old step-daughter who lives with her mother in another state. We have recently been told that we have to come up with almost 2500 dollars to put braces on her teeth. There is no medical reason for them. She has a beautiful smile, and when we asked why she was getting them the answer we got was, "She's not happy with her smile." We do not have the money to pay for this. We are on the verge of losing our home, and the orthodontist refuses to discuss the issue with my husband because he's not the custodial parent. The entire thing is a mess. Our daughter has never taken good care of her teeth. Half of her teeth have already rotted and been extracted because she doesn't brush them. We feel braces will only make that worse. She doesn't need them, and we are expected to pay for nearly the entire bill. Any thoughts on this?