Since a day ago, I have pain in the tooth I had a root canal done on about 2 years ago. I have a permanent crown and have never had a problem with it. But now I can't even chew it's so painful. It was even throbbing in the middle of the night therefore I didn't sleep well.

Is the pain possibly coming from a tooth next to it? Or could you have injured the gum next to the root-canaled tooth? Not long ago I bit down wrong on a Pringles chip and poked my gum next to a tooth that had had a root canal, and experienced awful pain until the gum finally healed a couple of days later.

If this doesn't ease up in a day or so, please visit your dentist for a checkup.

Doesn't necessarily mean it is that particular tooth. It could mean your bite is off, but you don't say where the crown is, top or bottom, but extra pressure is being put on that crown. Remember that our teeth move around and are not firmly based for number of reasons.

Good example for having periodical x rays and cleaning especially when you have crowns. Something is probably out of elignment, as simple as that. Go for a Check up.