Cancer Patient Treated with Radiation Therapy: Fixed-Detachable vs. Overdentures?

Dr. W. asks:
I have a 65 year old male patient who has a history of head and neck cancer treated with radiation therapy 5 years ago. He has no saliva and as such has rampant carries. His remaining teeth are to be extracted and implants placed. My question is whether a fixed -detachable (i.e., hybrid) would be preferable to overdentures. He would prefer a fixed type appliance. But I am wondering in the long term if it would be better for him to have overdentures which could be removed and cleaned? I would like to advise my patient which treatment would be preferable.