Although they probably were around earlier (there are reports of false teeth from as far back as 700), we know that the first false teeth used in Europe was around the 1400's. Sometimes they were pretty disgusting and made from teeth provided by grave robbers or from people who pulled their own teeth and sold them.
Then there were teeth carved from animal bones or from ivory, which tended to rot after prolonged use. They weren't very stable in the mouth and were primarily tied to the user's remaining teeth.
In the late 1700's the production of false teeth made out of porcelain began and in 1791 a patent was taken out by Nicholas Dubois de Chemant in England. Within 30 years there were high quality, long lasting false teeth that resembled natural teeth being set onto gold plates. Unfortunately, this was too late for Wahington.
Today, false teeth are made out of synthetics such as acrylic and other plastics. The three main issues in the fitting of dentures are support, stability and retention. They all refer to the prevention of movement of the dentures in the mouth and the assurance of a good fit for comfort, oral health and appearance.
There are fewer problems with a top denture as the suction created with the palate usually is enough to keep it from slipping, but a lower full denture is a different story as there is no suction keeping it from moving. This is the reason that today dentists recommend the support of dental implants on the lower jaw (usually 2-4) to anchor a bottom denture in place. This will ensure the permanence of the denture and its totally natural functioning.