Most people suffer from a mild form of gum disease (gingivitis) that can sometimes produce sore and bleeding gums, and often the plaque will harden on the teeth forming a hard deposit (calculus). A small proportion of the population (10-15%) are, however, more susceptible to the effects of plaque and permanent damage may be caused to the attachment of the gum to the tooth (periodontitis). This can result in the formation of gaps between the gums and the teeth (pockets) in which more plaque can collect and thus continue the disease process. As the pockets deepen, the supporting bone around the teeth can gradually be lost and the teeth may become loose.
Periodontal disease can in most cases be controlled, to avoid further loss of bone around the teeth, but there is no cure and lost bone cannot usually be replaced.