Periodontal diseases are associated with specific types of bacteria:

Periodontal diseases are associated with specific types of bacteria. If the plaque is not removed by regular brushing and dental floss, it hardens and turns into a rough and porous substance that is called calculation (also known as tartar).
The bacteria in dental plaque produce and secrete toxins that irritate the gums. These toxins cause the destruction of the fiber that adheres to the tooth gum, creating periodontal pockets, which are filled with more toxins and bacteria. As the disease progresses, the bags are made more profound and bacteria can penetrate further down to the bone that holds the teeth is destroyed. Eventually the tooth falls out or is required extraction.