A new and improved toothbrush could help avoid trips to the dentist A toothbrush that generates electricitymay more effectively fight harmful bacteria, while removing plaque, than existing products. The toothbrush uses special bristles that produce electricity as they bend, triggering the formation of molecules that damage bacterial membranes. When put to the test, it led to more than twice the reduction of plaque, gum inflammation and bleeding as conventional toothbrushes.
Anything that even slightly improves the way dental care works could have a benefit, because oral disease is just so widespread.” Oral diseases, such as tooth decay, affect nearly half the global population. Brushing regularly can help remove plaque, a sticky layer of bacteria that forms on teeth. These bacteria can produce acids that cause cavities and irritate gums, sometimes leading to tooth loss.
But even thorough brushing can leave behind bacteria deep in plaque or between teeth, allowing colonies to grow back within hours. Researchers have previously developed toothbrushes with antibacterial metal nanoparticles, including silver and zinc, embedded in their bristles, although their long-term effectiveness is uncertain. Others have designed ionic toothbrushes that use electric currents to help loosen plaque, but they are dependent on batteries.
Now, Yanhui Lu at Peking University in China and her colleagues have turned to studies showing that so-called piezoelectric materials fight bacteria in infected wounds and medical implants. These generate electric charges under pressure, prompting Lu’s team to develop toothbrush bristles made from piezoelectric plastic. The idea was that, as the bristles bend during brushing, they would generate electricity, triggering chemical reactions that produce molecules called reactive-oxygen species that damage bacteria, while the bristles physically remove plaque.
The researchers made two sets of bristles of different thicknesses, both of which met Chinese national standards for softness and strength. Laboratory tests confirmed the bristles generated electricity under pressure, particularly the thicker ones. The team also detected reactive-oxygen species on the brushes, which remained soft and retained their electrical properties after three months of use.
Next, the researchers exposed two common oral bacteria to their bristles and nylon ones, which are used in standard toothbrushes, in laboratory experiments, including simulated brushing movements. The thicker piezoelectric bristles were particularly effective, killing about 53 per cent of _Streptococcus mutans_, which causes cavities, and 78 per cent of _Porphyromonas gingivalis_, which contributes to gum disease, compared with just 9 and 8 per cent, respectively, for nylon bristles. The team also grew plaque from human mouths on pieces of cow enamel and brushed them for 3 minutes.
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