Why does putting aluminium foil in the mouth cause pain

Why does putting aluminium foil in the mouth cause pain  

Most people have at some time experienced a severe pain in their teeth after accidentally eating a piece of sweet wrapper. Those teeth that hurt are usually nowhere near the scrap of wrapper. The only people who escape this nasty sensation are those without metal fillings in their teeth. 

The type of sweet wrapper referred to here is generally made of aluminium metal, even if we call it silver paper . Such aluminium dissolves readily in acidic, conductive electrolytes and the pH of saliva is about 6.5-7.2. 

The dissolution of aluminium is an oxidative process, so it generates several electrons. The resultant aluminium ions stay in solution next to the metal from which they came. We generate a redox couple, which we define as two redox states of the same material . 

Two redox states of the same material are called a redox couple. 

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