For centuries, artisans in Japan’s Kishu region have been burning—and then rapidly cooling—oak branches to yield Binchotan charcoal, renowned for its purifying properties. Now it’s the secret ingredient in an understated black toothbrush. Binchotan charcoal is blended into each soft bristle to give it a boost of deodorizing, plaque-removing, and bacteria-preventing power that also wards off bad breath. Toothpaste optional.