Aluminum foil and fillings

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.

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.

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

Well, alrighty, then.

Er, is this going to sting?