Teeth get stained due to several factors. Smoking cigarettes causes extrinsic stains, which appear on the outer layer of the enamel. The same goes with drinking too much coffee, soda, and wine and eating food that can discolor the teeth.
There are also intrinsic factors that affect the color of the enamels, including excessive exposure to fluoride during childhood, trauma to the tooth, and internal bleeding. Aging is another cause of teeth stains. The enamel covering the teeth gets thinner over time, making the dentin, which naturally becomes yellowish, show through. Read more from this blog: