I faced a similar situation with a molar in the radiation field. They ended up performing a root canal and decapitating the tooth. It now is just a stump with a cap over it. An extraction could have been very serious and result in possible loss of the jawbone. Implants are dicey in irradiated areas and actually cause more problems. The worst case scenario is removal of the jaw bone. Keeping your medical team in the loop is a must. Perhaps a consult with a dental oncologist is in order.