There are more than 600 strains of bacteria in an average human’s mouth. Some do good, while others can do harm to your teeth and gums. Tiny food particles mixed with saliva form a slimy biofilm, called dental plaque, on which these harmful bacteria thrive. Starchy and sugary foods are bacterial favorites since they are sticky and hard to remove from the teeth’s surface (think candy and granola bars). If it’s not removed from your teeth, plaque can calcify into tartar.