Well I have had cankor sores my whole life too and you are absolutely right about chocolate and coca-cola. My dentist went to a conference and found out that whole wheat bread is also bad as well as cinnamon. I thought this was interesting. But he did tell me to start using Rembrandt toothpaste for cankor sores and it has made a big difference on a dily basis for me. As for the yeast build up I will be VERY interested to see if anyone has any more insight on that. Maybe the wheat bread has something to do with that?