lol, the minimum voltage is 3 volts according to the specs. Why would you put 3 volts on such a chip? AFAIK did the >2.5v age end in the late '90s. My fellow Dutchmen (the company Philips has Dutch roots) can be so hilarious sometimes.
I just brush with a brush without cpu. Clean teeth is more a matter of how you brush than the technologies used, IMHO. And what Oral-B states, i.e. that such a spinning brush can clean by spinning around each individual tooth, seems nonsense to me because most people have their teeth standing immediately next to each other, witout that much gaps.