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Want Whiter, Cleaner Teeth? Go For The Green Light, New Method Suggests

Previous methods can damage the teeth and aren't always super effective. This could be better.


Dr. Katie Spalding

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory.

Freelance Writer

Baby got that gling gling. Image credit: Billion Photos/, IFLScience

Americans, as everybody knows, are obsessed with having bright white smiles. This is a shame, since the natural color of teeth – even very well-cared-for ones – is probably closer to butter than bleach, but nevertheless, something like one in 10 Americans go in for artificial whitening treatments each year in the pursuit of that Hollywood gleam.

These procedures aren’t just expensive, they’re also – somewhat ironically, since they’re often chosen as a way to simulate better dental health – potentially pretty bad for your teeth.


But a new study, published in the American Chemical Society’s Applied Materials and Interfaces journal, has come up with an alternative solution to the problem of super-yellowing teeth: a new hydrogel treatment, which can break apart cavity-forming biofilms and whiten the teeth without damaging them.

“Biofilm-driven caries and tooth discoloration are two major problems in oral health care,” write the authors. “The current methods have the disadvantages of insufficient biofilm targeting and irreversible enamel damage.”

That’s because current methods – even those used by professional dentists – often rely on hydrogen peroxide-containing gels and blue light, which together produce a chemical reaction that removes stains. It works pretty well – in fact, if anything it works a little too well: the reaction removes discoloration, sure, but the hydrogen peroxide can also break down and weaken the enamel.

So instead of hydrogen peroxide, the researchers looked for an alternative method to whiten teeth. At first, they tried using modified titanium dioxide nanoparticles – a natural choice, as titanium dioxide is the most widely-used white pigment and already found in most toothpastes. But this method still required high-intensity blue light to work, which, with its ability to damage the skin and eyes, was a dealbreaker for the team.


Green light would provide a safer alternative to blue – so the team went hunting for a whitening gel that could be activated by that color instead. They mixed together nanoparticles of bismuth oxychloride, copper oxide and sodium alginate into a thick paste, which they applied to the surfaces of teeth stained with everyday pollutants like coffee, tea, blueberry juice and soy sauce.

After a coating of paste, the teeth were sprayed with a calcium chloride solution, forming a strongly adhering hydrogel, and exposed to green light.

“Reactive oxygen species was effectively released on demand under green light,” the paper notes, “which could not only eradicate the biofilm but also whiten the tooth… without significant damage to both the enamel and biological cells.” 

But it gets better: not only is this tooth-whitening method less destructive, it may actually be good for the teeth. In a separate set of experiments, the team found that the treatment was not only effective at removing biofilms – that is, things like plaque, which are formed by a pile-up of bacteria sticking to each other and the teeth – but it killed 94 percent of the bacteria found in them. 


And unlike many dental treatments, these results aren’t solely limited to petri dishes. The team also tested the whitening technique on mice whose mouths had been treated with cavity-forming bacteria – and the results were just as hopeful, with the teeny teeth effectively staving off moderate and deep cavities after the experiment.

So who knows – maybe next time you go to the dentist, your checkup will be replaced with a bright green light. All we need to do now is figure out which color can replace the pain of braces, and we’re set.


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