Your teeth can become discolored by stains on the surface or by changes inside the tooth.
There are two main types of tooth discoloration:
- Extrinsic — These are stains on the surface of the tooth. Coffee, cola, wine or other drinks or foods can stain teeth. Smoking also causes extrinsic stains.
- Intrinsic — This is when the inner structure of the tooth darkens or gets a yellow tint.
Intrinsic stains may be caused by tooth traumas (a broken tooth or chipped tooth) and dental conditions. Genetics can also play a role in the color of your teeth and their tendency to stain. Aging can also cause both extrinsic and intrinsic tooth stains.
However, sometimes teeth look yellow because the hard enamel has eroded away, revealing the dentin underneath. Dentin is a naturally yellow, bony tissue that lies underneath the enamel.