There are two types of toothbrushes – electric/battery powered and manual.
ELECTRIC toothbrushes are either an oscillating/rotary type or a vibration type. They allow better access to difficult to reach teeth and areas of the mouth. People who brush too hard can benefit since the action is stopped with too much pressure.
MANUAL toothbrushes ideally should be of a medium texture with a small to medium sized head. The brush should be held at 45 degree angle where the gum and tooth meet, using small circular motions for effective plaque removal and to minimise tooth wear through over brushing. For more information you can search for the Bass Technique on YouTube, it gives a demonstration.
Whichever brush you are using you should always brush for at least two minutes, twice daily.
As with manual toothbrushes the heads of electric and battery brushes should be changed every 3 months.