Why does it hurt when biting on aluminium foil?

If you've ever had the unpleasant experience of biting on aluminium (or aluminum for our American friends) foil you would perhaps find this post to shed some light on why such a trivial piece of foil can cause such unexpected pain.

Firstly when aluminium comes into contact with a different metal in your mouth, say a filling. The two metals will have different electrochemical potentials which effectively mean they have different numbers of electrons. As we know, charge always spreads equally throughout one object (as the metals are connected) and due to metals being electrically conductive, the electrical charge will flow between the metals. This electric charge is in fact electricity since electricity is simply the flow of electrons. The current generated will flow into the root of the tooth and thus into the nerve.

The body's Central Nervous System is how we are able to sense our surroundings, the CNS operates by the brain perceiving signals sent from sensory neurons (receptors) in the form of electrical impulses. The sensory nerve in the tooth receives and electrical current from the Voltaic Effect which causes the current to be produced by the metals. This electrical charge is also how the nerve sends information when experiencing pain and thus the brain perceives the flow of electrons as such since it is unable to distinguish the difference. 

At least you have now found the reason behind why we experience this painful reaction. And now you know, avoid putting aluminium anywhere near your mouth.

Until next time...