Ive had teeth discoloration all my life. Odd looking tan lines running in the middle of my tooth , light brownish yellowish haze to them in certain areas. My dentist said it was from tetracycline, and there was nothing that takes it away and unfortunately he was right. For my wedding, i got my teeth bonded and it looked pretty good but they only last about 4-7 years. I started to try my own method of "cleaning" and i noticed it has helped brighten my teeth a bit. Then i asked my dentit about it and he said it was fine to do that. I put a big goop of tooth paste on my teeth from left side to right side, and let it sit there for about 5 -10 minutes or however long i can stand it. Then i brush. It really does make a difference, but there is no method to getting rid of the staining inside the tooth itself. I may not have the whitest teeth but after doing what i have been doing, i cetainly have very clean teeth<img src="i/expressions/face-icon-small-happy.gif" border="0"> ~ Diane