Górsim the vault-keeper agrees to help you find the necklace made from Scatha's teeth.
'Fine, fine! It's the teeth of Scatha you want to see, then? Oh, don't you worry, I know right where to find them. And you are lucky you found me. Those are in the old vaults. Hardly any dwarf knows the way back there, other than me! And if Fróthi sent you, I am happy to show them off. I would not mind taking a look at the old things, myself, now that I think of it.
'I will return shortly. Please, drink some while you wait. No, no, I insist. In fact, I will be offended if you do not!'
You should have a drink while you wait for Górsim, in Erebor.
Górsim can be found at one of the older vaults in Erebor.