Periodontal disease is a bacterial infection of your gums. It happens when plaque and tartar are left to build upon the teeth for too long, and occurs in two stages: gingivitis and periodontitis.
In gingivitis, plaque and tartar on the teeth have just begun to irritate your gums. Your gums might be tender and swollen and bleed when you brush or floss them, but no permanent damage has been done yet, and the effects are reversible. If left untreated, however, gingivitis develops into periodontitis.
In periodontitis, the plaque and tartar on your teeth irritate your gums to the point where they begin to pull away from the teeth, creating “pockets” between your teeth and gums. These pockets are highly susceptible to collecting bacteria and debris that further irritate your gums and cause them to recede even further. As this cycle continues, the tissue and bone structures that hold your teeth in place slowly decay, which frequently leads to tooth loss.