I've noticed the same thing on my teeth. I've been OP for about 5 days and did it almost the whole day today because I've had a very painful gum infection I want to get rid of. I use organic EVCO. Well, initially, my teeth were MUCH whiter! I should say, I've also been using hydrogen peroxide as a mouthwash, so that could account for some of it too, but I think it was mostly the OP. Well, yesterday, my teeth became grayer and transparent. Today, they were more so. Alarmingly more so. Also, I have painful red bumps all over my tongue and a slight sore throat. We've had sick kids so that could be that or it could be the OP via cleansing or some other phenomenon. My teeth are very hot/cold sensitive today. Obviously the EVCO has not stained them but has it caused a de-mineralization? I was OP for like hours today. Was that a mistake? Please help.