Oral-B iO 9 electric toothbrushes have 7 brushing modes. This is the most amount of modes of all iO models. They have a tongue brushing and massage mode, for example. The iO 9 toothbrushes use 3D tracking. With this, you can see if you're brushing all sides of every tooth properly in the app. You also receive a rechargeable travel pouch with these models. This way, you can charge your toothbrush everywhere.