Say 'Ahh': The toothbrush will see you now

When the Oral-B Genius goes on sale in July, it will cost around $250. It brushes your teeth in much the same way as a $30 toothbrush from the same manufacturer - though it tries to make sure you haven’t missed a spot.

It's a smart toothbrush -- so smart, in fact, that with the help of a smartphone app it watches while you brush and tells you which bits could use a little more work. The brush handle contains gyroscopes, accelerometers and a Bluetooth connection to report its movement and orientation to the phone, which uses its camera to figure out where the brush head is in relation to your head.

At Mobile World Congress in Barcelona, the company invited visitors to try the brush out at its booth, under the watchful eye of dental professionals.

It was a slick operation, with four bathroom sinks each equipped with a smartphone and, when I visited shortly after lunch on Wednesday, a queue of people eager to clean their teeth.

A brush designed to provide around two weeks of normal use between charges (about 30 two-minute brushings) wouldn't last long at a busy trade show, so the company had dozens of brushes on hand, sliding one into a fresh disposable plastic sleeve for each visitor and popping a new brush head on top.

With the Oral-B App in "Challenge" mode, I was invited to brush my teeth as I normally would, while the brush and app monitored where I was brushing.

I'm a somewhat slow and methodical brusher in adulthood (sadly, it wasn't always this way), always following the same route and regularly finishing long after my $30 electric toothbrush, also an Oral-B, has buzzed to tell me my two minutes are up. It was no surprise, therefore, that before I had finished I was invited to stop brushing my teeth and see how I had scored.

The app then displayed a stylized picture of a mouth, highlighting how well it calculated different areas that had been cleaned.

It gave me an overall score of 54, which was fair, as I had only cleaned the teeth of my lower jaw and the backs of my upper incisors.

However, it was a little confused as to which teeth I had actually brushed: On the advice of my dentist, I start behind the lower incisors. I then work my way all around the lower jaw till I'm back where I started, but for the Genius app, I hadn't cleaned my lower incisors at all. As far as it was concerned, though, my upper incisors were sparkling clean, front and back.

I drool as I brush, so I tend to hunch over the sink -- all the more so when I'm trying not to drool on my jacket. This caused problems for the app, which on a couple of occasions asked me to keep my head still and look at the phone, so that may be how it lost track.

If your brushing technique is to roam around randomly, Roomba style, in the hope that you will eventually brush off all the crud, then having the Genius app try to keep track for you may be of some value, but if you have a routine and stick rigorously to it, then $250 may be a little too much to pay.

There's more to the Genius brush than just the position tracking function, of course.

The handle contains pressure sensors which respond in three ways to help you clean your teeth without damaging them. At the first sign of overpressure, a warning light comes on. If you continue to press too hard, the motor will stop "pulsing," lightening the impact on teeth and gums, and finally, the brush will switch to a slower, gentler cleaning mode until the pressure is released. The light came on a couple of times for me, a little less often than when using my brush at home.

There's no doubt the Genius has some clever touches.

Figuring out how to use accelerometers to monitor its position while it kicks around at 30,000 vibrations per minute is no mean feat -- although the task of filtering out that noise was made easier, said Oral B's R&D group manager Frank Kressmann, because "We know the frequency of the motor."

There's an element of "gamification" to the experience, as the app records your performance each time you brush and lets you know how it compares to previous sessions, subtly encouraging you to do your best. When the Genius launches in July, it will be possible to upload your scores to the cloud, Kressmann said, but by default it will all stay on your phone.

The pressure warning light, which glows green by default and turns red when you press too hard, uses an RGB LED. That made it trivial to allow the app to change the default color, personalizing the brush for different users.

"The color of lighting is very emotional," said Kressmann. "If you bond with the brush you are more likely to come back for the next brushing event."

If you need a toothbrush that can outsmart you in order to get your teeth clean, then the Oral-B Genius may be worth the premium, but I will be sticking to my routine and my $30 classic model.