Regardless of what you may think of the practise of teeth-whitening, it appears to not just be a passing fad – and it can harm peoples' teeth. Scientists from China's Nanchang University are out to make it safer, with an experimental new technique.

Currently, the most common form of whitening involves the application of a hydrogen peroxide gel, which bleaches the teeth by stealing electrons from the pigment molecules that cause surface discoloration. Exposing the teeth to blue light boosts the chemical reaction, significantly speeding the process up.

Unfortunately, however, high concentrations of hydrogen peroxide are known to break down a tooth's enamel, causing increased sensitivity or cell death.

Led by Xiaolei Wang and Lan Liao, the Nanchang team instead looked to titanium dioxide nanoparticles that had been modified with a polymer called polydopamine. When evenly applied to a tooth that was then irradiated with blue light, the nanoparticles produced a whitening effect similar to that of hydrogen peroxide, yet they were much less cytotoxic (toxic to cells). No significant damage to the enamel was detected.

As an added bonus, the nanoparticles were shown to kill certain types of bacteria. It should be noted that the blue light exposure lasted for four hours, though, which is much longer than a typical hydrogen peroxide treatment.

A paper on the research was recently published in the journal ACS Biomaterials Science and Engineering.