It's recommended to brush your teeth for 2 minutes at least twice a day. We use an egg timer in our bathrooms to help everyone keep up with how long they've been brushing.
I have a Braun professional care spin brush in my closet that I don't use anymore because they went way up on the cost of the replacement heads (even on eBay). During the couple of years that I used that I would end up with not as nice of dental checkups, i.e. the gums weren't always in perfect shape, but when I use just a regular ordinary toothbrush I have perfect checkups. They say that you can tend to get lazier about brushing with one of these fancier brushes and I believe that.