Whats dental floss made out of besides wax and string?

Synthetic fibers. Some are made of synthetic fibers, depends on the manufacturer.
Nylon or Teflon. Usually synthetic fibers like nylon, or monofilament tape liketeflon. The fibers can be puffed up to create a yarn like material. Flavors are sometimes added. The all work the same by mechanical disruption of the plaque colony.