Dwarf Rings

[inglorion]

The dwarven rings were something special. They were made for the same purpose as the Nine; to enslave their wearers to Sauron.
Only dwarves proved a little harder in fading then Men. They didn´t become wraiths but instead became very greedy and it was the rings that made the dwarves create their gold-hoards. They became immensely rich.
Sauron had no power over the dwarves, so he tried to gather back the rings, which he did except for the ones destroyed by the dragons.

I am not sure if all this is correct, I remember to have read it somewhere.

As for the One Ring, Gandalf says no dragon is now alive with the fire hot enough to harm the One Ring, nor was there ever save maybe Ancalagon.