Electric toothbrushes such as a Sonicare or Oral-B are very effective in plaque removal and keeping the oral cavity healthy in between dental cleanings.  They also typically have built-in timers and shut off automatically after 2 minutes.  Manual toothbrushes can be effective as well if used properly and for at least 2 minutes. However, studies show that 40-50% more plaque is removed with electric toothbrushes than with properly used manual brushes. Soft bristles are recommended for both manual and electric toothbrushes.