Ever since I was young, I've been to the dentist and had cavities filled. (My mouth has always been terrible, whereas my brothers, who never brushed-lol-was great).

I brush twice a day, floss nightly, etc, but still really struggle with cavities unless I'm on a 100% whole food diet. My childhood dentist told me that I had terrible teeth due to genetics, in that the enamel was poor and so was the tooth composition.

Anyways, I have one root canal and a mouth full of fillings, and I'm 31. So getting my fillings out is not some little thing, but something HUGE. And so is paying for it (which isn't an option at this point, I don't think. At least, I don't see how, currently, though it's something I could save for).

My question is, once they take the fillings out, what do they do? What is used to fill the empty place?