It’s just an unfriendly reminder that you have fillings (or some other metal dental work). When two different metals come into contact, an electrical charge passes between them. That’s the zap you feel when tinfoil touches the metal in tour mouth. The jolt travels from the tin to your tooth’s nerve through the filling. People without dental work won’t experience this sensation – yet another reason to brush and floss regularly!
The electric shock travels from the foil into the filling or crown, and then into the nerve. The shock is then sent to the brain as a pain sensation, because that’s what it is, pain. The final step in the process is to remove the foil and NEVER do it again.
The reason your friend didn’t feel any pain is because they more than likely haven’t had any dental work done in the way of fillings or crowns. Essentially, if your mouth is in perfect condition and has never been touched by a dentist, you will feel no pain from chewing aluminum foil.
Picture Credit : Google