They say chill with the candy/chewy/hard foods because it can actually damage the braces. The "disasterous" results with smoking are in referance to teeth discoloration. When you get your braces removed, the little square spots where they glue the braces to your teeth will be less discolored than the non glued spots. If you take special care and brush well, you will have even colored teeth. If not, its gonna be ugly. So to answer your question weed will be fine, when you smoke cigs just remember too clean your teeth well.