So are you thinking like a traditional doggie rope toy but instead of individual pieces of thread -- it would be dental floss?
Mammoth Flossy Chews Rope White Bone Dog Toy - Toys - Dog - PetSmart
Maybe the OP means something like picture in the link, but made with dental floss? I would imagine that would take a ton of floss...
I don't have any idea on whether or not a dog could chew on that -- I would suggest looking into the ingredients in the floss (i.e. whether the chemicals/flavors could be toxic). I'd be careful if making it at home though -- don't want any dangerous accidents!