Softly brushing your teeth at least twice a day is recommended. ''Three times a day is best," says Sesemann.
With too much time between brushings, he says, bacterial plaque will build up, boosting the risk of gum inflammation and other problems.
Brushing should last at least two minutes, says Sesemann. Three minutes is even better, says Price.
Most people fall short of both time lines, says Sesemann. "It's an arbitrary number, but it's just so people take the time to clean all the surfaces." He often recommends people divide the mouth into quadrants and spend 30 seconds a quadrant. Some electric toothbrushes include built-in timers.
To make the two minutes go faster, Sesemann says he ''multitasks,'' fitting in a little TV viewing as he brushes.
Cited from http://www.webmd.com/oral-health/healthy-teeth-10/brushing-teeth-mistakes