Aluminum foil and fillings

[El_Kabong]

I will accept my flogging like a good sailor if this question has come up before, but a cursory search indicates that it hasn't.

This came up during a conversation with friends earlier today. Can anyone explain the precise reason for the unpleasant sensation that occurs when a bit of aluminum foil comes in contact with metal dental fillings? I seem to recall it is electrical in nature.

[AskNott]

When you get two different metals immersed in the same acidic or salty liquid, you're likely to get electrical action going. This is related to why you can run a clock on a potato, and why the sea will sometimes eat a boat's propeller if there is no sacrificial piece of zinc nearby. Now, if you'll excuse me, I'll stand back while someone who understands chemistry explains why this stuff happens.

[Arjuna34]

Cecil has addressed this in a related column:
http://www.straightdope.com/classics/a1_121a.html

I found it by search for "aluminum foil teeth" in the "search the archives" section.

Arjuna34

[El_Kabong]

Well, alrighty, then.

Er, is this going to sting?