I am on my 8th set of trays for invisalign. I brush my teeth with sensodyne constantly clean my trays the way I'm supposed to be, I don't drink coffee, wine, or soda. My teeth are so stained that there almost black. I went to my dentist the other day and she didn't know what was wrong but she polished my teeth and it helped but she has done that before and its come back worse. why is this happening and will it go away when invisalign is done with?