Friend of mine does not have the whitest teeth. She consulted her dentist about the whiteners and bleaches. He told her to leave her teeth alone. She's 56 with the strongest, straightest cavity free teeth. A little on the yellow side. He told her to lay off the coffee. That has helped. She has all 32 and that's saying something. Her teeth are off-white but all there. Iused whiteners and bleaches and now have an upper plate.