You already know that you must brush your teeth, but are you aware that your tongue should be brushed also? Brushing your tongue helps to remove bacteria and food particles. A build up of bacteria on your tongue is the number one reason for bad breath.
It is ideal to brush in a downward motion. That will help you get rid of any food particles that may be caught between teeth and along the gum line. Brushing sideways is okay, but you need to also move your brush up and down to be effective.
