I had a tooth that reabsorbed. I never felt any pain with it and didn't even know I had it. After an xray revealed that it was a reabsorbed tooth, my dentist referred me to an endodontist. He wanted to do a root canal, but couldn't guarantee that the tooth wouldn't "explode" when he attempted it. I moved to a new area and let it go for five years. It slowly reabosrbed more and the new endodontist said it needed to be dealt with so I did have a root canal done and crown put on it and the tooth is fine.
I hope this helps.