Sounds like a trip to the vet's is in order.

One of Kewpie's fangs (I think they are called canine's even in a cat) was just gone one day, healed just fine, so next time at the vet she examined her to make sure there was no pain, no root pieces exposed or left behind. She said anything could have done it, and it was not a health concern for her (she was only 4)

Considering the tooth hasnt fallen out and obviously couldnt be healed I'd get to the vet and let them remove it and look the cat over.