"Prophies" are also known as dental cleaning.  Prophies are non-therapeutic procedures that help you keep a healthy mouth.  Prophies involve removing the plaque and tartar that have built up on the teeth over time.  Your teeth are constantly in contact with your saliva which contains calcium and other substances that help to strengthen your teeth.  The excess calcium tends to accumulate on and around the teeth and can provide the perfect conditions for bacteria to grow next to the gum.  Prophies clean and leave the surface of the tooth smooth and help keep the bacteria from sticking to the tooth allowing for easier maintenance at home.