Thanks
Because it is weird.
OK, if you have silver amalgam fillings, the two different metals in contact, together with your saliva as an electrolyte, are combining to make a very simple battery - the current is small, but your mouth is sensitive.
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I’m going to bet most of us here haven’t eaten aluminum foil and won’t appreciate that it feels weird. Could you describe the weird feeling with a little more detail please.
I assume this is what you were really asking about. To those of us without such fillings it just feels weird because it’s a metal foil, which has a different texture to anything we consider food. Hammer it thin enough, like closer to gold foil, and we probably wouldn’t notice.
But you do get a tingle where the foil touches to amalgum fillings.
Its a galvanic aka voltaic cell. When you have two different metals connected by saline water.
I think of this OP whenever I look at my dog happily chewing on a ball of aluminum foil (usually which he finds as a trash item). The first time I saw it I thought I should run to take it away, to save him discomfort, remembering my feeling, before I calmed down.
ETA: Since I know nasty responses often follow my posts about my dog: yes, I take the aluminum ball away from him.
You also get a similar effect when you touch the mouthpiece of a brass instrument to orthodontic devices.
My 40 year old daughter, who has never had a cavity, will freak out others when she chews foil.
Isn’t aluminum slightly toxic? Maybe deliberately eating it is not the best idea.
In Soviet Union horror movie, aluminum foil eats you.
Why Does it Feel Weird to Eat Aluminum Foil?
In addition to the other answers provided above, it might be helpful to point out that aluminum foil is not made of food…
the OP means chew, not eat.
And if you have no metal in your mouth, the concept has 0 meaning for you.
To anyone with metal in their teeth, it feels like you bit into a 9volt transistor battery.
It shocks you
Because it isn’t food?
Another aspect, that has nothing to do with dental fillings, is that a ball of aluminum foil will compress without rebounding or crumbling. I can’t think of anything else (at the moment) that behaves that way. Gum doesn’t compress so much as squish (as you bite down, it spread out horizontally); meat and vegetables tend to rebound (rubbery vegetables) or break apart (e.g. broccoli, celery); bready stuff tends to crumble or slightly rebound.