My girlfriend, who I've been with quite a while now, somewhere along the line discovered my, shall we say 'admiration' of braces. When she was little she used to have braces, had to wear headgear and elastics etc. Somewhere in our relationship she discovered I like them, and things along the line of 'well I'll proberably never be able to get braces for you', to which I replied 'Well.... there is this site that sells fake braces etc' to which she instantly offered to get made for her.
I never dreamed of anyone understanding me liking braces, yet alone offering to wear them for me. But its been a few months now, since I recived my order of her fake braces from this site (which are brilliant and I highly recommend their service BTW). Of course, we have a completely 'normal' sexual relationship as most partners do, however she wares the braces sometimes for me and even acts very sexy in them for me! She'll wear braces for me, headgear for me, and does various sexual things to do with it, let me take photos, lets me really explore it freely etc (lets not go into too much detail shall we) She even discovered she likes it when I wear my retainer and do stuff for her, she was amazed to find out it actually turns her on.
Not to make anyone jelous, but I thought I'ld say, because you never know, it is a possibility your girlfriend or potential girlfriend will understand like she did me. You just have to confidence to talk about it I guess, I never thought it was possible but it sometimes is!