Congratulation on 4 years!
It's best to check with your RO. I had right tonsil cancer, and was radiated bilaterally, 70Gy to primary, basically from the bridge of my nose down to the collar bone, including the front of mouth, jaw, although different areas received different radiation dosages. I did HBOT previously for a tooth abscess/necrosis, but none for any root canals, and will have to treatment for my tooth extractions in the future. My case, and doctors require HBOT. Not all doctors believe HBOT is necessary, and depends on where radiated, the time from radiation, the radiation dosage, usually above 45Gy has an effect on ORN, mainly the mandible, and with injury from oral surgery, tooth extractions, dental implants, rubbing of dentures, use of biphosinates, increase ORN risk.
http://www.oralcancerfoundation.org/dental/hyperbaric.phpGood luck with everything.
