Gentle Care brush heads are designed to optimize your iO brushing experience, giving your teeth the feeling of a professional clean every day. 100% healthier gums in 1 week (*vs. manual toothbrush). To maintain effectiveness, dentists recommend replacing your brush head every 3 months. A worn brush head makes cleaning even more difficult, leaving millions of plaque-causing bacteria behind. Compatible only with Oral-b iO™ toothbrush.