Why Teeth Stain, and Which Stains Come Out

Teeth discolor in two quite different ways, and knowing which one you have decides whether the fix costs 100 dollars or 2,000. Surface stain sits on the outside of the enamel and mostly polishes off. Internal color is the tooth itself, and no amount of cleaning touches it.

This guide covers what causes each, what a cleaning and whitening realistically do, what neither will change, and the one kind of color change that is a symptom rather than a stain.

Surface stain sits on the enamel and mostly polishes off

Enamel is not glassy smooth. It has a thin protein film on it that picks up color from whatever passes through your mouth, and that film binds tightly to plaque and tartar. Coffee, tea, red wine and tobacco are the usual suspects, and the stain builds slowly enough that most people do not notice until they see an old photo.

The tell for surface stain is where it collects: heaviest at the gumline, in the grooves, behind the lower front teeth, and around any crowding where a brush skips. It is often darker on the tooth surfaces you clean least well, which is a useful hint about technique rather than a moral failing.

• Coffee, black tea, red wine, cola and dark fruit juices
• Smoking and chewing tobacco, which stain deeply and quickly
• Curry, tomato based sauces, soy sauce and balsamic vinegar
• Chlorhexidine mouthwash used for more than a short course
• Liquid iron supplements, and some other medicines

Internal color is the tooth itself, and whitening is the only lever

The color you see is mostly dentin, the yellower layer underneath, showing through translucent enamel. As enamel thins with age and dentin thickens from the inside, teeth get gradually darker and yellower. That is normal and it happens to everybody.

Some internal color has a specific cause. Tetracycline antibiotics taken while teeth were forming can leave gray or banded discoloration. Too much fluoride during development leaves white flecks or mottling. A tooth that took a knock years ago can slowly darken to gray or brown as the nerve inside dies, and that one is usually a single tooth, out of step with its neighbors.

Whitening gel works by getting peroxide through the enamel to break down the pigment inside. That is why it changes internal color at all, and also why it is slower and less complete on deep tetracycline banding than on ordinary age related yellowing.

A cleaning removes stain, whitening changes color, and they are not swaps

A hygiene appointment removes tartar and polishes stain off the surface. For a lot of people that is the entire answer: teeth go back to their own natural shade and look dramatically brighter, because what they had was a film, not a shade problem. It also removes deposits that gums react to, so there is a health reason to do it anyway.

Whitening changes the underlying shade. Done at a dental practice it is either an in office session or custom trays with gel to wear at home, sometimes both. Results vary by starting shade, by how the gel is used and by the tooth itself, and sensitivity during treatment is common and usually temporary.

Costs vary by city, by practice and by case, but a hygiene visit is often somewhere around 75 to 200 dollars, custom take home trays with gel commonly run around 250 to 600 dollars, and in office whitening is frequently 400 to 1,000 dollars. Ask what happens if the result is uneven, and whether top up gel is included.

Whitening will not fix fillings, crowns or white spots

Crowns, veneers, bonding and white fillings do not whiten. If you brighten your natural teeth around an old front filling, that filling will suddenly look darker, and matching it means replacing it afterward. That is a real cost, so raise it before you start rather than after.

White spots are the other common disappointment. Whitening lightens the whole tooth, so a chalky white patch often stays visible or looks briefly more obvious before the surrounding shade evens out. Those spots are usually handled differently, with resin infiltration, microabrasion or bonding, and a dentist can tell you which is realistic for yours.

Habits that keep teeth lighter without costing anything

The point of these is not to give up coffee. It is to reduce the contact time between pigment and enamel, and to avoid brushing while the enamel is softened by acid, which is when abrasion does most damage.

One warning about charcoal and heavily abrasive whitening pastes. They can scrub away the film and look effective for a while, but abrasive damage is permanent, thinner enamel shows more yellow dentin underneath, and you end up darker than you started.

• Drink coffee, tea and cola in one sitting rather than sipping over hours
• Rinse with water after anything dark, and wait about an hour before brushing
• Use a straw for iced coffee and dark soft drinks
• Keep up hygiene visits, since fresh stain lifts far more easily than old stain
• Skip charcoal pastes and anything that feels gritty enough to scour

When a color change is a symptom, not a stain

One tooth going gray, brown or pink on its own is worth an appointment, particularly if it was ever knocked. That usually means the nerve inside has died, and it does not resolve by itself. Internal bleaching through the tooth is one option once the inside has been treated, and it is only possible because the discoloration is coming from within.

Brown or dark patches that feel rough, catch floss or have a soft edge can be decay rather than stain, and white patches near the gumline that appear over a few months can be early decay too. Neither is something to judge from your own bathroom mirror. If you need somebody to look, the directory searches every dental practice in the United States by town or ZIP code and shows you the closest first, free and with no account.

Bring photos if the change has been gradual, and mention any injury to that tooth however long ago it was. A tooth can darken years after the knock that caused it, and the history saves a lot of guessing.

Frequently asked

This is general information to help you ask better questions, not a diagnosis. Anything happening in your own mouth needs a dentist who can look at it.