What causes gum disease (gingivitis)?

One of the main causes of gum disease is the plaque bacteria that builds up around, on and in between your teeth. If it is not removed by regular brushing and flossing it can irritate your gums, causing them to become red and swollen, and they may bleed when you brush or floss your teeth. This stage of gum disease is called gingivitis. If these early signs of gum disease are not treated, then it can eventually progress to the more serious form of gum disease, periodontitis, which is irreversible and can lead to tooth loss.