question: Dear Sir My teeth are becoming yellowish and also I have several stain mark on them. I used to brush my teeth twice a day, regularly. I used to do profession teeth cleaning once in a year. My friends have white clean teeth. They are as careful as I am. But, My teeth are becoming white some days after profession teeth cleaning. My font teeth are also becoming thinner by days. That I am not sure but I feel. Is it fluorosis? Please suggest how to get rid of the stain problem ?