Radiation, especially the method that they use to use say 5 years ago, can destroy some of the blood flow to our teeth. Also the damage to our saliva glands leaves us with a dry mouth condition that doesn't bathe the oral cavity like normal.

Also the typical Oral Cancer patient of the past usually presented with bad oral hygiene practices and less than perfect teeth so it was common practice to just yank all the teeth because leaving bad, even sometimes good teeth in a mouth after radiation led to dead or dying teeth years later and then trying to remove them with weakened blood vessels made matters worse.

Then along came IMRT, a radiation that lessened the damage to the oral cavity so the old practice turned into one of lets fix the bad teeth and use fluoride trays and try to save all the teeth they could. Even so we still see some people that come here with the recommendation that all the teeth go and we try to get them to get another opinion just to make sure it's a necessity.