It is an inflammation of gums which progresses to affect the bone that surrounds & supports your teeth. Caused by the bacteria in plaque which is a sticky, colourless film that constantly forming on your teeth.
If not cleaned by daily brushing and flossing, plaque can build up and gets hardened to calculus ( blackish brown or brown or black color TAR TAR) and the bacterial colonies formed in it infect not only your gums and teeth but bone that support the teeth.
Differentiating about bleeding tendency can be a significant challenge by patient himself