Floss is useful for things other than cleaning teeth; it's fairly strong, lightweight, and you can get a lot for little money. You can use it to tie up things, as a wick for a candle or oil lamp, sewing (in a pinch), etc. Basically, get a small roll for your bug-out bag, make sure it is unflavored and waxed.
Once out of floss, I can either pull my teeth out (Well, OK, every _other_ tooth) or kill myself. Life w/o floss is unimaginable.