I suspect it’s like pieces of the true cross, enough to have come from an entire forest, every two bit conman carved some George Washington wooden teeth as a curio fostering the story and some ending up in museums and collections.
Basically the USA’s Shroud of Turin.
Wood would be a bad medium for false teeth, they would absorb moisture, warp and splinter, and rot. Real teeth or hippo ivory makes much more sense. It’s like skulls, there used to be an abundance....
Here’s a scenario, Mab trades a favour to the young George Washington, by having her No 1 creepy Tooth Fairy extract the teeth and make his new dentures for him. Very Mab, in return getting the Crown out of North America gave her a far freer reign in the US than in England and Washington agreed to “no kings” and a Republic.
Note the teeth do not contain any iron only real teeth, hippo ivory, brass and gold and of course Mother Winter would be in a position to advise on their construction.