Gum recession is caused by bacteria that form in the pockets and creases of your gums, creating pockets of stagnant moisture. In order to keep bacteria from thriving in these pockets, your dentist will usually scrape away some of the tissue surrounding the bacteria with a root canal procedure. But, if the pockets are left untouched, they can develop into what is called pocket gum tissue. It’s this tissue that can begin to erode; exposing your body’s healthy-looking bone material below.