My brother and I are in our 40s and have grey teeth (kind of an opaque greyness to them - not chalky white at all). It's permanent and was caused when we took fluoride supplements when we were kids (right when our adult teeth were forming). We lived in a rural area with well water, so they thought that was the best treatment at the time.
I would guess that most dentists and pediatricians are familiar with that by now, and don't suggest that. My guess is that it's the iron, but I don't have any personal experience with that. I would call your dentist or doctor - I'm sure they can give you a bit of free advice over the phone.
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