The Oral-B iO Series combines powerful, but gentle micro-vibrations with Oral-B's iconic dentist-inspired round brush head design for a professional clean feeling every day. Ultimate Clean Refills help remove plaque, leaving teeth feeling clean and bright. Tufted bristles help clean hard-to-reach areas of the mouth. Dentists recommend changing your toothbrush head every 3 months for best results. Do not use on children under age 3. Replace brush every 3 months or sooner if brush head becomes worn.