Thousands of years ago, Etruscans living in western Italy first invented dentures. They make false teeth with gold or bones and put them between good teeth. 1770, the French began to make dentures with porcelain, which won't rust. This kind of porcelain denture is still in use today, especially for implanting individual dentures. The most famous denture man is American President George Washington. His false teeth are a whole row of teeth carved out of a piece of ivory. This material was not expensive at that time. Besides ivory, other materials for making dentures include walrus and hippopotamus teeth. In the past, it was difficult for people to eat with dentures. They usually take off their false teeth before eating. Charles Goodyear's invention of vulcanized rubber changed all this. This kind of rubber is an ideal material for making dental trays, and it is very cheap. Now we can make dentures of any shape with molds to suit everyone's mouth. With the development of the times, people began to use celluloid and plastic to make dentures. Dentures made of these materials are not only the same shape as real teeth, but also the same color.