Dentists love dental floss.
Dental floss is a thread, usually nylon, which is also available as a tape.
You use it to clean the crevices in between your teeth, where the bristles of your brush can't get to. Dental floss has been around for a long time. Marks from dental floss have been found in the teeth of early pre-humans, and American Indians. But the modern re-inventor of dental floss was a New Orleans dentist called Levi Spear Parmly. Back in 1815, he recommended that people should clean between their teeth with a thin thread of silk.