A toothbrush that generates electricity may 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.
鈥淭he concept is great,鈥� says at Newcastle University, UK, who wasn鈥檛 involved in the research. 鈥淏asically, the mechanical forces recharge the surface, so it鈥檚 really innovative. Anything that even slightly improves the way dental care works could have a benefit, because oral disease is just so widespread.鈥�
Oral diseases, such as tooth decay, affect . 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.
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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 , although their long-term effectiveness is uncertain. Others have designed , but they are dependent on batteries.
Now, at Peking University in China and her colleagues have turned to studies showing that so-called piezoelectric materials in infected wounds and medical implants. These , prompting Lu鈥檚 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. The new toothbrushes removed more than 99 per cent of the plaque, compared with about 80 per cent for conventional nylon brushes.
Finally, the team tested the toothbrushes in 109 adults with dental plaque and gum inflammation, who were randomly assigned to use either a piezoelectric or nylon toothbrush twice daily for three months. Dental examinations revealed reductions of roughly 40 per cent in plaque build-up, gum inflammation and bleeding among those using the piezoelectric brushes, compared with around 15 per cent for those using conventional brushes.
Genetic sequencing of the dental plaque from the piezoelectric group also revealed a decline in the relative abundance of harmful bacteria and an increase in some potentially beneficial bacteria.
Larger studies now need to establish whether the toothbrush actually prevents issues like cavities and tooth loss, says Jakubovics.
Science Advances
