hey guys i need help.when i was 8 i didnt brush well and my teath went yellow so for the past 3 years i kept havin to go to the dentist to clean it with somethin so wen i was about 11 i started to brush well and ive relised its not me its just the colour of my teath and it keeps goin back now im 13 it isnt as yellow as it is its alot less than before. and i keep brushing well and it keeps goin yellow but its gone better how do i turn it white?