Help me with a word!?

I need to know a certain word. It's for a report and my mind just blanked. My essay is about archaeology and how they found skeletons, and apparently they determined a skeleton's age by the... worn-ness?... of the teeth. I can't think of the word. I don't really want to rephrase my sentence, but I will if I have to. Please help me, it's due tomorrow.