There are many causes of surface stains, including tobacco use, certain medications and foods, and drinks such as coffee, tea and colas can cause teeth to become stained or discolored. These respond well to teeth whitening.
However, some causes of discoloration don’t. Of course, if your tooth has decay, whitening won’t help. It also won’t help if your tooth is infected, or if it’s been bruised by trauma. During the aging process, the outer layer of enamel on our teeth wears down, and the naturally yellow color of the dentin underneath begins to show, and whitening can’t help with this, either. It also won’t help if you have defects in the enamel structure.