Hello, I suspect you are not properly brushing your teeth..which a lot of people fail to do and don't know it..Do this...take some food coloring, any color, rinse your mouth with 1/8 teaspoon of it..don't swallow, spit it out and rinse with clear water...Then look at how all the debris in your mouth is now colored..Now brush all the color away and your teeth will be clean and you will know where the yellow went.
The Denture Pro.