Yellow Teeth: Why They Happen And What Helps

Why are my teeth yellow when I brush them every day?

Because brushing only reaches part of the problem. A toothbrush clears plaque and some of the stain sitting on the surface of your teeth. It cannot change the colour of the tooth itself, which comes from within the tooth, and it cannot shift plaque that has already hardened into tartar. So it is entirely possible to brush twice a day, every day, and still have teeth that look yellow. It does not mean you are doing it wrong. It usually means the yellow is coming from somewhere a toothbrush does not reach.

The useful question is which of three things you are looking at, because each one has a different answer.

The three things that make teeth look yellow

1. The colour of the tooth itself

Your enamel is not pure white, and it is not completely opaque either. Underneath it is dentine, which is naturally a deeper yellow, and some of that colour always shows through. The American Dental Association describes what happens over time: "With increasing age, enamel becomes more translucent and thinner, which allows the yellower dentin to show through and the overall tooth color may darken." The Oral Health Foundation puts it simply for a UK reader: teeth "can darken naturally with age".

This is colour from inside the tooth, which the ADA calls intrinsic, occurring "within the enamel or the underlying dentin". No toothbrush or toothpaste reaches it, however often you brush.

2. Stain on the surface

The second source is what the ADA calls extrinsic stain, "an accumulation of colored compounds on enamel". It comes from tea, coffee, red wine, tobacco and strongly coloured food. Brushing removes some of it every day, but if your habits lay stain down faster than brushing takes it off, it builds up regardless.

That alone can explain the brushing paradox in the title: somebody drinking several coffees a day is adding colour all day long and removing it twice. Tobacco stain builds up in the same way, and we look at it on its own in smoker's teeth and whitening strips.

3. Tartar, especially near the gums

Plaque that is left on a tooth does not stay soft. Great Ormond Street Hospital's patient guidance explains that plaque "will harden and calcify to produce calculus if it is given enough time", and that calculus "is a hard cement-like substance, which cannot be removed with a toothbrush. The dentist or hygienist will remove this extra layer from the teeth."

So if you can feel a rough, hard band on your teeth, particularly near the gums, show it to a dentist or hygienist. Brushing harder will not move it.

Can my teeth be yellow but healthy?

A yellowish shade on its own is not a sign that something is wrong. Tooth colour varies from person to person, and both the ADA and the Oral Health Foundation describe teeth darkening naturally with age. But colour alone cannot tell you that a tooth is healthy, and a dentist can, so a check-up is the way to be sure.

If you want to put a name to where yours sit, our guide to finding your starting shade explains how to read one at home in daylight.

The exception is change. A single tooth that turns darker than its neighbours, or teeth that change colour suddenly, are a reason to see a dentist rather than a reason to buy a whitening product. The ADA lists causes of intrinsic discolouration that include developmental conditions, fluorosis and certain antibiotics taken in childhood, and those are for a dentist to assess.

Why your teeth can look more yellow than they are

Before deciding your teeth are yellow, check the light you are judging them in. Warm light pushes everything it falls on towards yellow, teeth included, so a warm bathroom bulb is a poor judge. A phone camera adjusts its colour balance on its own, so the same smile photographed at breakfast and in the evening can come out as two different colours.

The fair test is daylight, near a window, at the same time of day, with something neutral in the frame to compare against. If your teeth still look yellow there, the three causes above are where to look. If they only look yellow under the bathroom light, part of what you are seeing is the bulb.

Can yellow teeth become white again?

It depends which of the three is responsible, and you may have more than one.

• Surface stain is the most movable. Cleaning, cutting down on what causes it and whitening all work on it, and our guide to removing stains at home sorts the different kinds apart before you spend anything.
• Tartar needs a professional clean first, because a toothbrush will not remove it.
• The natural colour of the tooth can be lightened, but not by cleaning. That takes a product that acts on the coloured compounds inside the tooth rather than on the surface, which is what whitening does.

Two honest limits apply whichever route you take. The Oral Health Foundation is clear that "whitening will not work on fillings, crowns or veneers", so dental work keeps its colour while the teeth around it change; we have covered what that means in our guide to whitening with crowns, veneers and bonding. And any shade change is a ceiling, not a target: how far you can go depends on where you start.

What brushing harder will not fix

When teeth stay yellow, it can be tempting to scrub harder or reach for something gritty. That does not help with the two causes brushing cannot reach, and an abrasive only ever works on the surface. We have looked at what whitening powders actually do in more detail, including what the evidence says about baking soda and charcoal.

A soft brush, gentle pressure and a mild, non-abrasive toothpaste are the better routine. Keep using a fluoride toothpaste for everyday brushing; a whitening product is something you add, not a replacement for it.

What actually helps

• Get tartar dealt with first. If there is a rough yellow band near the gums, a dentist or hygienist clean comes before anything else.
• Look at the source of the stain. The Oral Health Foundation notes that smoking and drinks like tea, coffee and red wine "can cause staining to return more quickly". Rinsing with water after a coffee costs nothing.
• Measure before you treat. Note your shade in daylight before you start anything, so you can judge the result properly rather than from memory.
• Use whitening for the colour of the tooth, not as a substitute for cleaning.

Why Pure Glow exists

Daniel, who founded Pure Glow, spent fifteen years at Jaguar Land Rover, six of them in health and safety. Working a three shift pattern, drinking a lot of coffee and smoking at the time, he noticed his teeth staining.

What he found when he went looking for a fix is the reason the product exists. Peroxide strips left his teeth sensitive and feeling brittle, and the non-peroxide strips he tried would not stay put. So he bought every whitening strip he could get hold of, catalogued every fault, and spent ten months testing before settling on the formula now in the box, after four were rejected.

Where whitening fits

Once tartar is cleared and you know your starting shade, whitening is the step that works on the colour of the tooth itself. Pure Glow's PAP whitening strips use PAP, an oxidising agent that acts on the coloured compounds in the tooth rather than scrubbing the surface. They are peroxide free and clinically tested for zero sensitivity, with hydroxyapatite included to support the enamel surface, and they give up to 6 shades whiter in 14 days, depending on where you start. If you want the chemistry, we have written up how PAP whitening works.

A result also needs keeping. Stain comes back at whatever rate your habits put it there, which is why we have a separate guide on how long whitening lasts. You can see both packs of our teeth whitening strips here.

The strips are not suitable for children under 12. If you have any concerns about your teeth or gums, speak to a dentist first.

The short answer

Teeth can look yellow despite daily brushing for three reasons: the natural colour of the dentine showing through, surface stain building up faster than brushing removes it, and tartar that a toothbrush cannot shift. Work out which you have. Tartar needs a hygienist, stain needs fewer sources and a clean, and the colour of the tooth itself is the job whitening is for.

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Related reading:

• Non-peroxide whitening strips

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Sources:

• American Dental Association, Oral Health Topics: Whitening. For extrinsic and intrinsic stain, causes of intrinsic discolouration, and enamel thinning with age. A United States source; the mechanisms it describes are not country specific.
• Oral Health Foundation, Tooth whitening. A UK charity, for natural darkening with age, staining returning more quickly with smoking, tea, coffee and red wine, and whitening not working on fillings, crowns or veneers.
• Great Ormond Street Hospital, Tooth plaque. NHS patient information for plaque hardening into calculus, which a toothbrush cannot remove. It is written for families of child patients; the process it describes is the same in adults.