Your dentist recommends a soft toothbrush to protect your teeth and gums from the damage that a firm bristle can do to your teeth and gums especially when combined with overly aggressive brushing. A firm bristle toothbrush can actually damage the enamel on your teeth and cause your gums to shrink leaving your tooth roots exposed. A soft bristle brush combined with gentle pressure and the right brushing technique will provide all the cleaning power you need. For more information, ask your dentist for advice on proper brushing and flossing techniques at your next appointment.