The enamel on your teeth is the hardest part of your body, but your teeth are the only organ that can't repair itself.
The Etrucians were amongst the first known "dentists" of the world. About 2700 years ago they carved false teeth from the teeth of various mammals. Their methods didn't change much for many years, and George Washington had teeth made out of things such as hippopotamus teeth, ivory, cow and sheep's teeth.
Nowadays medicine has changed a lot and going to the dentist isn't so painful and scary - at least if you don't think of the fact that the electric chair was invented by a dentist.