Chronic periodontitis is a form of periodontitis (gum disease) that progresses slowly over a long period of time. Like other forms of periodontitis, chronic periodontitis is caused by bacteria. The bacteria form plaque, a film that enables them to attach firmly to the surface of your teeth. When this plaque spreads below the gums, the toxins released by the bacteria irritate the gums. The body responds with immune cells and chemicals intended to fight the bacteria. But these can also attack healthy tissue, breaking down the gum and bone to which the teeth are attached.
Some of the most prominent characteristics of chronic periodontitis are open pockets that form around the teeth and gingival recession, meaning that your gum line gets lower, exposing more of your teeth.