Plague is a biofilm made of a variety of bacteria, saliva, and other particles that coats the mouth, teeth and tongue. When plaque bacteria digest the food in the mouth, acids are formed. The gums become inflamed as an immune response to the acid. Tenderness and bleeding are indications of this. Dentists call this gingivitis. If not taken care of, via brushing or flossing, the plaque can turn into tartar (its hardened form) and lead to periodontis or periodontal disease. While plaque can be removed with good oral care, tartar requires a dental hygienist to remove it. Cavities occur when plaque acids eat away at tooth enamel.