Everything You Ever Wanted to Know About Tooth Staining and More! (way, waaaaaaay more).

About 3 weeks ago, Lisa asked us why adding cream to your coffee (or milk to your tea for those of us with British heritage) would prevent or reduce staining to your teeth.  When I first started looking into this question I thought there would be no problem finding a straight-forward, highly researched answer. After all, we live in a society that’s clearly obsessed with a whiter smile. When visiting a new dentist this past month, half the questions on the intake sheet had to do with my level of concern over how white my teeth were (turns out I was more concerned by the inability to close my jaw – but it’s good to know someone’s looking out for my aesthetics).

No one's smile is perfect. Doesn't mean you shouldn't share it.

Yet despite all of the commercial interest in whiter teeth (most consumer reports site Americans as spending just over $1 billion on whitening products a year), scientists apparently have better things to research as there is very little in the scientific literature on the causes of tooth staining.  What little research there is tends to focus on the staining of tooth composites – things like resins that are used in crowns or false teeth.

Never fear though! After an exhaustive search (more on the physical than amassing side), we have come up with some extensive great background information on exactly what causes tooth staining that is sure to bore wow you!

Stained teeth look like new! (new what exactly?) royalyorkdental.com

Before you go running off to get the newest, fastest “bleaching kit” to ensure your pearly whites* stay their brightest, you should understand that not all teeth are created equal. In colour that is. In fact, tooth colour not only varies between people, but also on individual teeth. For example, the gingival (gum) margin is usually darker than the rest of the tooth; canine’s are typically darker than the central teeth; younger people have lighter teeth;  and due to differences in lighting your teeth can change colour throughout the day!

But tooth discolouration does exist, and it can be classified based on if it’s caused by intrinsic or extrinsic factors.

Intrinsic discolouration results from changes to the actual dental tissue.  While ‘normal’ tooth colour is determined by the pigments of the enamel and dentin, metabolic diseases and systemic factors can affect the developing dental tissue, resulting in changes to tooth colour.

Extrinsic factors are those that cause staining to the tooth after development, from things like food or metals. Many foods contain organic chromogens which impart the natural dark pigment you see in coffee and red wine. Unfortunately, chromogens can be easily incorporated into the outer layer of the tooth (the pellicle) resulting in staining. The more often you drink, the more staining you see.

Tannins are a related group of large polyphenols found in a bunch of plant extracts – including coffee, tea, and red wine – that readily bind to proteins. In fact, binding to proteins is how tannins got their name – tree bark solutions rich in these molecules were used to tan leather back in the days of yore. The teeth in your mouth are covered in a thin layer of protein, the pellicle, which will bond to tannins in coffee and tea and cause tooth staining. Chromogens can also bind to tannins, increasing the chance of staining.

As a grad student who’s diet consists of vast quantities of coffee, tea, and red wine, this is distressing news for my smile.

Munsell colour rating of 10YR 3/6.

So what if you add milk or cream to your coffee?

You might remember from our brief explanation of why old milk curdles in coffee that dairy proteins, such as casein, bond to tannins and other phenolic compounds in tea and coffee. In the same way that the protein-tannin bonds reduce the astringency (the “fullness” of tea, coffee, and red wine, caused by tannins binding proteins on the inside of your mouth), it also limits the number of free tannins available to bond with your tooth pellicle. I couldn’t find a study that compared the binding kinetics, how fast and tightly the binding occurs, of dairy and pellicle proteins, but considering the amount of time the tannins have to interact with the milk versus the pellicle, I’d say it’s a safe bet that few tannins that pass through your mouth release the bonded dairy proteins in favour of your teeth.

In fairness, there are some gaps in the evidence, but the logic train goes like this: tannins in coffee and tea bind to the pellicle and cause tooth staining, dairy proteins found in milk and cream readily bind to tannins, tannins bound to dairy proteins will be unavailable to bind to your teeth, so adding milk or cream to coffee and tea reduces tooth staining.

Unfortunately, because not all tannins will bind with the cream, and because the chromogens will still stain your teeth, the only way to avoid tooth discolouration is to completely forgo that cup of java. But really, who’s gonna go that far?

Thanks for the question Lisa! As always, we love getting your comments. Please take a moment to ask your own question or say what you think about this or any other article!

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*Ever notice how pearls aren’t actually all that white? Also how they’re iridescent? What if you really like black pearls???
Hagerman, Ann E. Phenolic Compounds in Food and Their Effects on Health I. October 1, 1992, 236-247
Joiner A, Muller D, Elofsson UM, Arnebrant T. Ellipsometry analysis of the in vitro
adsorption of tea polyphenols onto salivary pellicles. Eur J Oral Sci 2004; 112: 510–515
Omata Y, Uno S, Nakaoki Y, Sano H, Yoshida S, and Sidhu SK. 2006. Staining of Hybrid Composites with Coffee, Oolong Tea, or Red Wine. Dental materials journal, 25(1): 125-132.
Padiyar N, and Kaurani P. 2010. Colour stability: An important physical property of esthetic restorative materials. International Journal of Clinical Dental Science. 1(1):81-84.
Praystino S, Taylor L, Cadogan S, and Addy M. 1979. An in vivo study of dietary factors in the aetiology of tooth staining associated with the use of Chlorhexidine. Journal of Periodontal Research. 14:411-417.
Proctor GB, Pramanik R, Carpenter GH, and Rees GD. 2005. Salivary Proteins Interact with Dietary Constituents to Modulate Tooth Staining. Journal of Dental Research. 84(1):73-78.
Walters PA, Biesbrock AR, and Bartizck RD. 2004. Benefits of Sodium Hexametaphosphate-Containing Chewing Gum for Extrinsic Stain Inhibition. Journal of Dental Hygiene. 78(4):2-8.
Watts A, and Addy M. 2001.Tooth discolouration and staining: a review of the literature. British Dental Journal. 190(6):309-316
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5 Responses to Everything You Ever Wanted to Know About Tooth Staining and More! (way, waaaaaaay more).

  1. Adam says:

    Teeth components such as dentin also contain protein which means the tannins is not just bind to the pellicle but to the other teeth components as well.

    Like

  2. Lisa says:

    Thanks for your exhaustive explanation!!! I can’t wait to pass it on to my patients. (I’m a hygienist) I often tell people about the link between cream and less staining, but until now I couldn’t say why it is so!

    I LOVE your website! I have tried the shaken cold water bottle trick…and to the 10-yr old who was helping me, I have attained genius status! Can’t wait to go camping and boil an egg in a paper bag!

    Like

  3. BrocStar says:

    Interesting!
    I’m surprised the milk industry hasn’t thrown money at some scientists to do a full study on this. The next great set of milk adds would show big, pearly white smiles with cups of coffee and gallons of milk (95% milk, 5% coffee, of course.)

    I’m guessing this answer is no since the tannins specifically bind to dairy proteins, but would a soy or almond milk exhibit similar affects?

    Like

    • Actually tannins will bind to all kinds of proteins! Soy milk has about the same protein content as cow’s milk, so it should bind those tannins too. If your cream-free creamer reduces the tea’s astringency (its cheeck-tightening mouthfeel), it will more than likely also reduce staining. Thanks for reading!

      Like

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