A toothbrush that generates its own electricity with every stroke could offer a new way to fight the microbes behind cavities and gum disease.

Conventional toothbrushes rely on physical scrubbing to remove plaque from teeth and gums. But even after a thorough brush, some bacteria remain and begin rebuilding plaque. To solve that problem, researchers have developed a self-powered toothbrush that converts the friction of brushing into an electrical charge. That electricity is intended to zap the plaque-promoting bacteria and keep them from colonizing teeth.