Inflammation of the soft tissue (gingiva) and abnormal loss of bone that surrounds the teeth and holds them in place. Gum disease is caused by toxins secreted by bacteria in "plaque" that accumulate over time along the gum line. This plaque is a mixture of food, saliva, and bacteria. Early symptoms of gum disease include gum bleeding without pain. Pain is a symptom of more advanced gum disease as the loss of bone around the teeth leads to the formation of gum pockets. Bacteria in these pockets cause gum infection, swelling, pain, and further bone destruction. Advanced gum disease can cause loss of otherwise healthy teeth.

Bacteria in plaque, a sticky, colorless film that constantly forms on your teeth, cause gum disease. If plaque is not removed it can harden and turn into tartar (calculus). Additionally, dental plaque will continue to form on the tartar. Brushing or flossing cannot remove tartar; a dental professional will need to conduct a dental cleaning to remove it.

Evidence Links Stress and Periodontal Disease
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https://www.medicinenet.com/script/main/art.asp?articlekey=3640
http://www.colgate.com/en/us/oc/oral-health/conditions/gum-disease/article/the-three-phases-of-periodontal-disease-symptoms-0814
http://www.colgate.com/en/us/oc/oral-health/conditions/gum-disease