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Teeth discolor for different reasons, and the fix depends on the cause. Surface stain from coffee, tea, wine and tobacco comes off with a cleaning. The yellowing of age responds to whitening. Deep discoloration from tetracycline, fluorosis or a tooth that has lost its nerve lightens only partly with whitening and may need a veneer or a crown, and a single dark tooth needs an examination first, because a dead nerve may be infected. Old fillings and crowns do not whiten and are replaced to match.
What makes teeth discolored
Surface stain. Coffee, tea, red wine, dark sauces and tobacco leave pigment on the enamel, particularly where plaque has been allowed to sit. It looks like a yellow or brown film, heaviest near the gum and between the teeth. It is cosmetic, and a professional cleaning and polish removes most of it.
Age. Enamel thins over the decades and the yellower dentin beneath shows through more, while pigments from a lifetime of food and drink work their way into the enamel. This is the ordinary yellowing that whitening addresses best.
Discoloration from within. Some teeth are dark because of what happened while they were forming or afterward. Tetracycline antibiotics taken in childhood leave gray or brown bands through the teeth. Too much fluoride in early childhood leaves white or brown mottling. A tooth that has lost its nerve, after a knock or deep decay, turns gray or brown on its own. These colors sit deep in the tooth, and whitening gel, which works from the outside in, lightens them only partly.
Old dental work. Fillings and bonding on front teeth stain at the edges and yellow with age. A crown with a metal core shows a dark line at the gum as it recedes. None of these change color with whitening; they are replaced.
What helps, by cause
For surface stain: a professional cleaning, and a look at the habits and the home care that let it build up. Many patients find that the cleaning alone gets them most of what they wanted.
For yellowing: professional whitening. We favor a slow course in custom trays worn at night over fast in-office methods, because it gives excellent results with less sensitivity. Younger teeth tend to whiten faster; older teeth respond too, with a longer course. Whitening changes color only, not shape, and it works on natural tooth structure only.
For a single dark tooth: an examination first, because a tooth that has lost its nerve may be infected without symptoms. A root canal comes first when it is; afterward the tooth can be lightened or covered with a veneer or crown to match its neighbors.
For deep discoloration: when whitening cannot reach the color, porcelain veneers mask it, with a thin layer of ceramic designed by a master ceramist to match the teeth around them. Tetracycline staining and very dark teeth are among the cases where veneers are the right answer, and we recommend them. A heavily damaged tooth may need a crown instead.
For old fillings and bonding: replacement, matched to the shade of the surrounding teeth. Composite bonding renews a discolored edge or corner; a discolored crown is remade in all-ceramic material with no metal to show.
The order matters
Whatever the plan, whitening comes before any new dental work on the front teeth, never after. Fillings, bonding, veneers and crowns are matched to the shade of the teeth around them and do not change afterward, so the natural teeth are whitened first, the color is allowed to settle for a couple of weeks, and only then is the new work made to match. Patients who have it done the other way round end up with restorations that look dark against their newly whitened teeth. Our cosmetic dentistry page walks through the full sequence, including where alignment fits in.
What whitening will not do
- It will not change the shape of a tooth, close a gap or straighten anything.
- It will not lighten crowns, veneers, fillings or bonding.
- It lightens deep internal discoloration only partially.
- It is not permanent without maintenance: teeth pick up pigment again over time, and a night or two a month with the trays keeps the shade.
Frequently asked questions
Will whitening work on my teeth?
If the color is yellowing from age or stain that has soaked into the enamel, usually very well. If the darkness comes from inside the tooth, from medication taken in childhood or a tooth that lost its nerve, whitening lightens less, and we talk about other options.
Why is one tooth darker than the rest?
A single gray or brown tooth has usually lost its nerve, often years after a knock. It needs to be checked, because a dead nerve can be infected without hurting. After a root canal, the tooth can be lightened from the inside, or covered with a veneer or crown.
My old fillings have gone dark. Can they be whitened?
No. Fillings, crowns and bonding keep their color. Dark or mismatched restorations on front teeth are replaced to match, ideally after whitening the natural teeth so the new work is matched to the final shade.
Is the stain damaging my teeth?
Surface stain from coffee, tea, wine or tobacco is cosmetic, not harmful, and a professional cleaning removes it. Tobacco itself is a different matter for the gums and the mouth.
What should I do first?
Have the teeth examined and cleaned. That removes surface stain, treats anything that must come before cosmetic work, and tells us which kind of discoloration you actually have, which decides everything else.
Sources
Professional guidelines and peer-reviewed reviews this page draws on.
- Carey CM. Tooth whitening: what we now know. Journal of Evidence-Based Dental Practice. 2014;14(Suppl):70-76. DOI
