I wish I had known before I invested over 200 pounds in two of these devices and countless brush heads. After the two years warrenty period, it slowly brakes piece by piece until you are left with more landfill. Very clean and lovely teeth, but companies should stand by their products - especially their top of the range products. Not happy and will not buy again. Wish I knew what I know now.

I was given a Smart Oral B as a gift and i loved it. Apart from spending a fortune on all the different kinds of heads, it can become a little compulsive.
However, all that changed when just a little over the 2 year guarantee, my tooth brush died, it just no longer charges. I have spoken to customer services and apparently it seems my battery has come to the end of it's life expectancy. Once this happens, the whole unit is defunct. The dead battery can't be replaced, nor can you buy just a new hand held unit to use with your current smart system. Apparently they expect the battery to last for 3 years, but this depends on how often you brush your teeth, three years is based on brushing for 2 min twice a day. Naughty me must have brushed my teeth more than that since mine only lasted just over two years.
So just be aware the unit will only last 3 years at the very most. Then it will become landfill.
I think they should tell people this when you are looking to buy it. Does the British Dental Health Foundation, who recommend it, know that the more you brush your teeth with this product the more you reduce it's working life. Not the brush heads, that makes sense, but the whole unit becomes defunct!