Stained teeth: what causes it, and what actually whitens.

Discolouration comes in two broad types. Extrinsic (surface) stains sit on the enamel, picked up from food, drink and smoking — these respond well to cleaning and whitening. Intrinsic (internal) discolouration is within the tooth, from things like ageing, certain medications, trauma or excess fluoride in childhood — these don't lift with normal whitening and may need veneers or bonding to change. Telling the two apart is the whole reason a quick assessment beats guessing.

Surface stains come mainly from coffee, tea, red wine, dark sauces and tobacco, and build up faster where plaque is not cleaned away. Internal discolouration has different roots: ageing (enamel thins and the yellower dentine beneath shows through), tetracycline antibiotics taken in childhood, trauma that darkens a single tooth, excess fluoride (fluorosis), and root-canal-treated teeth that grey over time. A single dark tooth usually points to internal causes rather than diet.

For surface staining, the basics do most of the work: brush twice a day, clean between the teeth, and don't let staining drinks sit — rinse with water after coffee, tea or wine, and consider a straw for cold ones. Cutting down tobacco makes a large difference. Regular professional cleans remove the built-up stain a brush can't. None of this changes internal colour, but it keeps the surface bright and makes any whitening last longer.

For surface stains, a professional clean plus whitening lifts the colour safely and predictably. For internal discolouration, normal whitening has limited effect — depending on the cause, options include internal whitening of a single root-treated tooth, or veneers or bonding to cover deep staining that won't bleach. Whitening lightens your own teeth within their natural range; it cannot turn a deeply discoloured tooth pure white. An honest assessment of which you have is what sets realistic expectations — see our shade guide.