Tooth Stains: What Actually Removes Them, and What Doesn’t

Cosmetic Dentistry

8 min read  •  By Dr. Kevin Baharvand, DMD, MS  •  Updated August 2026

Somebody buys a whitening toothpaste, uses it for two months, and decides their teeth are just naturally yellow. That is usually the wrong conclusion drawn from a real observation.

The toothpaste did what it could do. It removed surface stain. If the yellowing was coming from inside the tooth, it was never going to touch it, and no amount of extra scrubbing was going to change that.

Here is how to tell which one you have, which determines everything else.

Surface stain versus the colour of the tooth

Extrinsic stain sits on the outer surface of the enamel. Coffee, tea, red wine, curry, tobacco, and some prescription mouth rinses deposit pigment that accumulates in the microscopic texture of the enamel and along the gum line. It responds to physical removal, which is why teeth look noticeably brighter after a cleaning.

Intrinsic discoloration is the tooth itself. It comes from the dentin underneath, which is naturally yellow and shows through the enamel. As enamel thins with age or wear, more of that yellow shows. It also comes from certain antibiotics taken during tooth development, from fluorosis, and from trauma.

The quick self test: brownish or grey deposits, especially near the gum line and between teeth, are usually surface. An even yellow across the whole smile that has crept in over years is usually intrinsic. A single dark tooth is neither, and it needs looking at rather than whitening.

Tap and drag the table sideways to see every column.

Why scrubbing harder makes it worse

This is the part worth understanding, because the whole abrasive whitening category depends on people not understanding it.

Every toothpaste has a measurable abrasivity. Some whitening pastes, and most charcoal products, sit at the high end. They work by physically scraping the outer surface, and they do remove surface stain, so they appear to work at first.

The problem is what is underneath. Enamel does not grow back. Thin it over years and more of the yellow dentin underneath shows through, and the tooth gets darker. So the product marketed as whitening produces, on a long enough timeline, a yellower tooth. It also exposes more of the root surface at the gum line, which is softer, stains more easily, and is more prone to sensitivity and decay.

We covered the charcoal version of this question in more detail in is charcoal toothpaste safe.

What peroxide actually does

Peroxide is the only thing in the consumer category that changes the colour of the tooth rather than cleaning its surface.

It diffuses through the enamel into the dentin and breaks apart the pigmented molecules that are causing the discoloration. That is a chemical process happening inside the tooth, not a scrub.

That is why contact time matters more than concentration for most people. A lower strength gel held against the teeth for longer often outperforms a stronger product that rinses away in two minutes. It is also why whitening toothpastes containing peroxide do relatively little: they are on your teeth for about ninety seconds and then go down the sink.

The three practical formats are strips, custom trays from a dentist, and in office treatment. Strips are cheapest and work reasonably for mild yellowing. Custom trays hold the gel against the teeth properly and cover the surfaces strips miss. In office is the fastest and the most controlled.

The thing that catches people out

Whitening does not affect crowns, veneers, bonding, or fillings. At all. They stay exactly the shade they were made.

So if you have a white filling on a front tooth and you whiten successfully, you now have a tooth that is lighter than the filling in it. The filling did not change. Your tooth did.

The sequence to avoid this is: whiten first, wait about two weeks for the colour to stabilise and any peroxide to dissipate, then have the restoration replaced to match the new shade. Doing it in the other order means paying for the restoration twice.

Same principle applies with veneers and crowns, except more expensively. If you are planning any front tooth restorative work and you also want whiter teeth, say so at the planning appointment.

If whitening makes your teeth hurt

Sensitivity during whitening is common, it is usually temporary, and it is manageable rather than a reason to quit.

Peroxide temporarily increases the permeability of the tooth, which is what causes the cold zings. It settles within a day or two of stopping.

What helps: use a toothpaste with potassium nitrate for a couple of weeks before starting, whiten every other day instead of daily, shorten each session, and use fluoride afterward. Do not respond to sensitivity by whitening more aggressively to get it over with.

And if one tooth is sharply sensitive rather than a general zinginess across the smile, stop and have it looked at. That is a different signal.

What to expect, honestly

Whitening works well on yellow. It works less well on grey. It works poorly on banded antibiotic staining, which is the one case where people are often genuinely disappointed and where a cosmetic conversation is more realistic than a bleaching one.

Results are also not permanent. Depending on what you drink and whether you smoke, expect to touch up somewhere between every six months and every couple of years. Custom trays make that cheap, because you already own the trays and are only buying gel.

And the least glamorous advice remains true. The single biggest improvement most people can make to how their teeth look is a cleaning, because the stain that bothers them is sitting on the surface and has been for two years.

Common questions

Does whitening toothpaste actually work?

It removes surface stain, which can make teeth look brighter. It does not change the internal colour of the tooth, because abrasives cannot reach it and the paste is not in contact long enough for peroxide to act.

Why are my teeth still yellow after whitening toothpaste?

Because the yellowing is likely coming from the dentin inside the tooth rather than stain on the surface. That responds to peroxide whitening, not to polishing.

Can abrasive toothpaste damage teeth?

Over time, yes. Highly abrasive pastes wear enamel, which does not regenerate. Thinner enamel shows more of the yellow dentin underneath, so teeth can end up looking darker.

Will whitening work on my crowns and fillings?

No. Crowns, veneers, bonding, and fillings do not change shade. Whiten first, wait about two weeks, then match new restorations to the new colour.

One of my teeth is darker than the others. Will whitening fix it?

Probably not, and it needs diagnosis first. A single dark tooth often means the nerve inside has died, which is treated differently and may involve internal bleaching after a root canal.

How long do whitening results last?

Typically six months to a couple of years depending on coffee, tea, red wine, and tobacco. Custom trays make touch-ups inexpensive since you only buy the gel.

You may also be interested in these

• Is charcoal toothpaste safe?
• Should you brush before using whitening strips?
• Pop-on veneers: are they worth it?