Activated charcoal toothpaste: does charcoal whiten teeth?

Activated charcoal toothpaste has become something of a beauty trend in recent years, popping up in commercial and natural toothpastes alike.

Some charcoal toothpastes act like a normal toothpaste and just add a little charcoal to help things along. Others, though, feature activated charcoal as a main ingredient and rely on it to clean teeth, remove stains and handle the bacteria in our mouths.

In this article, we’re going to dig a little deeper into the hype and see whether activated charcoal whitens teeth for real. .

But first, let’s find out a bit about what activated charcoal actually is.

Where does activated charcoal come from?

Activated charcoal is made from wood and other plant matter like coconut shells or willow tree.

First, the plant matter is strongly heated in the absence of oxygen (slow pyrolysis). Crucially, the lack of oxygen prevents it from catching fire, but the heat is enough to remove all the water. What is left at the end of this process is good old normal charcoal, a black crumbly substance which is between 85 and 98% pure carbon.(1)

You’ll have come across this type of charcoal before in everything from barbecues to artist’s materials, where it is often used because of the deep rich black colour it adds to sketches.

To ‘activate’ the charcoal, it must be put through either a physical or a chemical activation process.

Physical activation involves exposing charcoal to carbon dioxide, oxygen or steam at a very high temperature.

Chemical activation employs acids such as phosphoric acid or sodium hydroxide to the plant material and following it up with pyrolysis.

After undergoing these processes, the charcoal becomes very porous and its surface is covered in many tiny crevices and cracks. This drastically increases its surface area.(1)

Because of its large surface area, activated charcoal is able to adsorb other substances very effectively. Adsorption means that it grabs these substances and holds them to its surface, clinging to them almost like a film.

This special ability has encouraged people to use it in all sorts of ways throughout history, from treating poisonings to improving digestion. Head to our sister article to find out more about what activated charcoal does.

Why is activated charcoal used in toothpaste?

Activated charcoal has been used for a very long time as a natural toothpaste, as it has qualities which lend themselves to cleaning teeth.

It has a grainy texture, which means it can act as a natural abrasive. It physically removes staining on the tooth’s surface by polishing it away.

This is actually what most commercial whitening toothpastes do, although they use different abrasive substances like calcium carbonate or silicon dioxide.(2)

For this reason, it’s best to limit your use of charcoal toothpaste, perhaps switching in a different one between uses, to make sure you’re not wearing down your enamel too much.

Abrasives can wear down eroded tooth enamel more easily, so whichever toothpaste you use, it’s best to keep an eye on the state of your enamel.(3) This is even more important if you suffer from a tendency towards tooth decay.

It’s also worth noting that neither activated charcoal or regular toothpaste can get to internal staining, or stains which lie beneath the tooth’s surface. To tackle those kinds of stains, you would need to look at a professional whitening service with your dentist.

Does charcoal whiten teeth?

Due to its natural abrasive properties, it seems that activated charcoal does help remove external staining.

A 2019 study found compared charcoal toothpaste with a regular abrasive toothpaste. After four weeks, the study found that the charcoal toothpaste whitened the teeth more than the control toothpaste, although other compounds also showed whitening benefits.(4)

The study suggests that charcoal’s whitening effect comes from its ability to adsorb chromophores (molecules responsible for colour) within the mouth.(4)

A review by the Royal Pharmaceutical Society concluded that charcoal toothpaste may be most effective when used to prevent staining from reoccurring following a professional ‘scale and polish’. (2)