I tried a £500 toothbrush which claims to be the world's best - and the results were surprising

telegraph.co.uk:

Oral-B’s new iO 9 brush.Its launch last month caused a ruckus in the personal-care world, not only thanks to its 200,000 person waiting list  and hefty price tag (an eye-watering £500) but the fact it boasts 250 new patents – some of which have been years in the making - to help upgrade your brushing.Naturally Oral-B says it’s the best brush ever.

But the number one difference between the iO 9 and other electric toothbrushes is the brush head itself combines oscillation rotation with micro-vibrations, so it can hug the contours of each tooth to provide a deep but gentle clean.There’s also a smart sensor light which turns green when applying optimal pressure and indicates when too much or not enough is being applied – good if you suffer with.