My dentist said I did not need to have my teeth out, that if I used floride trays during my treatments, I should be fine and that she would work with me to keep them healthy, and I would say my teeth are no where near as good as your dads. But an oral surguion said they should all have come out. But after Questioning him, the reason for having the pulled out is mainly for treatment to the teeth afterwards. After the gums and teeth have been radiated, it just makes it more diffucult to work on the teeth and alot of the time it takes hospital stays to work on them, but if he has a good dentist, i wouyld keep all he can, beacause a lot of my fiends have false teeth and would do anything to have there normal ones back. Sorry I know it is a two sided sword, but I found it was better to get all the information you can find from all the sources, then let your dad make his own educated decisions. Will be think of you both and keep asking ??? because the more you know good and/or bad, the easier it is on you and your dad during your upcoming battle.