1 dentist says the tiny dark spot on xray at the root means root canal is needed another says its just irritation that a grind plate will help heal the tooth can still feel coldhot can it heal?

The Dark spot on the xray could be a number of things. i hope it isn't a lower premolar, because it could be the mental foramen. Anyway. If you still have hot/cold sensation it is a sign that the tooth is vital. ie the nerve still works. If you are having symptoms of discomfort. aka PAIN. then the tooth may have irreversible pulpitis. The Dark spot is a sign of abscess or inflammation. But could be an artifact or something else. The use of a cold test or EPT would give a more definative evaluation as to the vitality of the tooth in question compared to the others.

If it were me. i would wait to see if it heals and get reevaluated every few months to see if there is improvement. If you're still unsure, another opinion from an endodontic specialist might be a good idea.