"The Eye" by Alice Munro

"Yet for a long time when I did think of her, I never questioned what I believed had been shown to me. Long, long afterwards, when I was not at all interested in any unnatural display, I still had it in my mind that such a thing had happened. I just believed it easily, the way you might believe and in fact remember that you once had another set of teeth, now vanished but real in spite of that. Until one day, one day when I may even have been in my teens, I knew with a dim sort of hole in my insides that now I didn't believe it anymore."

The Eye 
Alice Munro