How Whitening Strips Can Harm Teeth


New research reveals that the active ingredient in whitening products can damage the layer beneath the tooth's enamel.

Americans are a people who love their pearly whites – to the tune of more than a billion dollars spent on teeth whitening products each year. But aside from the environmental harm from all the waste generated – the strips, trays, all that packaging – haven't you ever wondered if it is OK for the teeth?

While of course the manufacturers have studied potential ill effects and promise that the products are safe, now recent research throws the safety of these products into question.

In three new studies, researchers found that hydrogen peroxide, the active ingredient in over-the-counter whitening strips, can harm the dentin tissue that lies beneath the tooth's protective enamel.

The new research has been undertaken by a team of students under the guidance of Kelly Keenan, PhD, associate professor of chemistry at Stockton University in New Jersey. While most research on these products has measured the effects of hydrogen peroxide on tooth enamel, Keenan's team looked at what's happening beneath the enamel.

Teeth are made of three layers, including the outer enamel, then a layer of dentin, and then the connective tissue that binds the roots to the gum. Most of the tooth is comprised of the dentin layer, which has high levels of protein, mostly collagen.

Previous research has shown that hydrogen peroxide can penetrate the enamel and dentin. And in fact, previous research by Keenan's team found that collagen in the dentin layer was effected when teeth were treated with whitening strips.

"We sought to further characterize what the hydrogen peroxide was doing to collagen," said Keenan. "We used entire teeth for the studies and focused on the impact hydrogen peroxide has on the proteins."

What they found was that the collagen in the dentin is broken into smaller fragments when treated with hydrogen peroxide. They also subjected pure collagen to hydrogen peroxide and examined the protein with lab techniques that gave them a clearer picture of what was happening.

"Our results showed that treatment with hydrogen peroxide concentrations similar to those found in whitening strips is enough to make the original collagen protein disappear, which is presumably due to the formation of many smaller fragments," says Keenan.

So it is clear that the hydrogen peroxide can harm the dentin – but it remains unclear what this means in terms of permanent damage. The team explains that their research did not address whether collagen and other proteins in the teeth can be regenerated. Hopefully more will be revealed upon further research that the team plans on performing.

The new research was presented at the American Society for Biochemistry and Molecular Biology annual meeting during the 2019 Experimental Biology.