Oral-B iO Series Electric Toothbrush Replacement Brush Heads (6 Count Refills) The Oral-B iO Series combines powerful but gentle micro-vibrations with Oral-Bs unique 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. Gentle Care Refills use extra soft bristles to adapt to the curves of teeth and gums. Dentists recommend changing your toothbrush head every 3 months for best results.