Hello @phyllisg, I don't have any experience with radiation treatments but have had lots of problems over the years with issues caused by flavored toothpaste. I've been using Arm & Hammer Peroxicare for quite awhile now and haven't had any problems. I believe all of their toothpastes use baking soda as the cleaning agent or whatever they call it. They have several different types that might be a good alternative for your husband - https://www.armandhammer.com/oral-care/toothpastes. I'm tagging my knowledgeable friend @loribmt who may also have some suggestions.