About 30-40 years ago, I read an unsettling story called "The Itchy Teeth". Here's how I remember it:
There is a boy whose teeth itch. His mother is irritated by the constant sound of her son scratching at them with his fingernails.
The boy wants to stop irritating his mother, so he works with a chemistry set and creates a powder. When he puts the powder on his teeth, they stop itching ... but he becomes very small.
He shows the effects to his mother. In the last paragraph of the story, his mother sees how small he is, and puts her foot down on top of him.
I'd like to reread this disturbing short story. Google searches for "short story the itchy teeth" just come up with medical diagnoses of gum disease.