Periodontal disease is caused by bacteria that are normally present in the mouth. The bacteria convert sugars and starches into acids. A combination of bacteria, acid, food, and saliva form a sticky coating on the teeth, called plaque. The acid in the plaque damages the gums and the tooth enamel, which results in the formation of a cavity.

Plaque can crystallize to form a very hard coating, called tartar. Plaque and tartar can also cause gingivitis, periodontitis, and dental abscesses.