Plaque is a colorless, sticky film of bacteria that constantly forms on teeth. If left undisturbed, it hardens to form tartar. The bacteria in the plaque produce byproducts that can not only irritate the gums and make them bleed, but it can also lead to periodontal disease. A daily regimen of proper brushing, flossing and rinsing (plus, regular dental visits), will help you keep your teeth healthy.