If that lump in your neck is still there and he has not done at least a fine needle biopsy of it, get it done NOW. He can't tell from feeling it if it is a met from your tongue cancer or not, and "keeping and eye on it" means doing nothing in the meantime. This cancer moves quickly once it gets into the lymph system. You want to be sure that it is not there. For your health, for your peace of mind. Re treating your teeth. As long as it does not involve the bone surrounding the teeth, or soft tissue surgery which might heal slowly, treating radiated teeth is no different that treating normal teeth for the most part.