The Ionic Kiss toothbrush works on the simple principle that your teeth are negatively charged and plaque is positively charged: Opposites attract, so plaque adheres to teeth. (Click here for diagram.) The 3-volt lithium battery gives a negative charge to the brush head when the handle is moistened. During brushing, a positive charge is sent to the teeth, temporarily changing their polarity to positive. The positively charged plaque is then attracted to the negatively charged brush.