I would think that as long as the dental work does not involve bone or blood (as in extractions or work below the gum line) then it will not be a problem getting temporary work done.

As for the effects of radiation, everyone has a personal reaction. Some of us had relatively lower side effects and I have yet to see a common reason for those lower side effects. A stubborn positive attitude helps, as does a strong support system.

Your father will have to brace himself and pace himself. It is a slow and grinding process until he gets his last radiation treatment. Use humor and humility liberally. He can do this.

Mark, 21 Year survivor, SCC right tonsil, 3 nodes positive, one with extra-capsular spread. I never asked what stage (would have scared me anyway) Right side tonsillectomy, radical neck dissection right side, maximum radiation to both sides, no chemo, no PEG, age 40 when diagnosed.